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CHEIISTEY 
 
 IN ITS EELATIONS TO 
 
 PHYSIOLOGY AND MEDICINE 
 
 BY 
 
 GEOEGE E. DAY, M.A. CANT. M.D. F.E.S. 
 
 n 
 
 Professor of Medicine in the University of St. Andrews 
 
 With Five Plates, containing numerous engraved Illustrations 
 
 LONDON 
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B10L03Y 
 
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 BIOLO8? 
 
 LIBRARY 
 
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 PEIKTED BY SPOTHSWOODE AND CO. 
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INTEODUCTION. 
 
 IN the present volume I have endeavoured to compre- 
 hend in a reasonable space all the most important de- 
 partments of Physiological Chemistry. 
 
 I have taken Lehmann as my principal guide, and 
 have made free use of all his works in this department of 
 chemistry, namely, his " Lehrbuch der physiologischen 
 Chemie," in three volumes, his "Handtjuch der physio- 
 logischen Chemie " (of which a second edition, much en- 
 larged, appeared last year), and the "Zoochemie," which 
 he published in association with Huppert, in 1858, and 
 which, I believe, is intended to form a section of 
 Gmelin's great work on chemistry. I have likewise 
 borrowed a considerable amount of material from Eobin 
 and Verdeil's " Traite de Chimie Anatomique et Phy- 
 siologique," from Heintz's " Lehrbuch der Zoochemie," 
 from Schlossberger's " Erster Versuch einer allgemeinen 
 und vergleichenden Thier-Chemie," (which, when com- 
 pleted, will form a most valuable addition to chemical 
 literature,) and from Scherer's Annual Eeports on the 
 Progress of Physiological Chemistry. In the Chapter on 
 
 A 2 
 
 756913 
 
INTllODUCTION. 
 
 " The Urine," I have extracted much important matter 
 from Neubauer and Vogel's comprehensive volume, and 
 the last thirty pages of this chapter are little more than 
 a condensed translation from that work ; arid in con- 
 sequence of the extreme importance of the study of the 
 urine and urinary sediments to the physician, I have 
 entered into these subjects at much greater length than 
 their mere physiological importance would warrant. 
 Indeed, I venture to trust that this chapter will be found 
 to contain everything that a medical man requires to 
 know in reference to the subject of which it treats. In 
 the Chapters on " Digestion " and " Eespiration," I have 
 made free use of French's celebrated article in Wagner's 
 " Handworterbuch der Physiologic," and of Vierordt's 
 " Physiologic des Athmens ; " while the Chapters on 
 " The Metamorphoses of the Tissues " and " Nutrition," 
 are mainly founded on the works of Bidder and 
 Schmidt, of Bischoff and Voit, and on the corresponding 
 chapters in Lehmann's Handbuch. 
 
 The illustrations (with a few exceptions) are taken 
 from Funke's Atlas der physiologischen Chemie. 
 
 My aim has been to produce a work equally useful 
 to the senior student and the busy practitioner. 
 
 G. E. D. 
 
 July 31st, 1860. 
 
TABLE OF CONTENTS. 
 
 INTRODUCTION. 
 
 (1) Physiological Chemistry. Chemical Relations of Substances. Physio- 
 logical Relations. Chemistry of the Animal Fluids and Solids. Zoo- 
 chemical Processes. Division of the Subject. . . . Pages 1 2. 
 
 BOOK I. 
 
 THE ORGANIC SUBSTRATA OF THE ANIMAL BODY; THE PROXIMATE PRIN- 
 CIPLES ENTERING INTO THE COMPOSITION OP THE SOLIDS AND FLUIDS OP 
 
 THE ORGANISM. 
 
 CHAPTER I. 
 
 THE NON-NITROGENOUS ORGANIC ACIDS. 
 
 (2) Different Groups of Non-nitrogenous Organic Acids, with their Formulas. 
 Fatty Acids. Their Formulse. Their theoretical Composition. (3) 
 Oxalic Acid Oxalateof Lime Its physiological Relations. Its Origin. 
 (4) Chemical Characters of and Tests for the volatile Fatty Acids. (5) 
 Formic Acid. (6) Acetic Acid. (7) Metacetonic Acid. (8) Butyric Acid. 
 (9) Valerianic Acid. (10) Caproic, Caprylic, and Capric Acids. (11) 
 Origin of the above-named Acids. (12) Their Uses. (13) Chemical Cha- 
 racters of the solid Fatty Acids. (14) Margaricand Stearic Acids. Cocic, 
 Myristic, and Cetic Acids. Palmitic Acid. ( 1 5) Occurrence of the solid 
 Fatty Acids in the animal Organism. (16) The Succinic Acid Group. 
 Succinic Acid. Sebacic Acid. (17) The Oleic-Acid Group. (18) Dama- 
 luric and Damolic Acids. (19) Oleic-Acid. (20) Doeglingic Acid. (21) 
 The Benzoic- Acid Group. Benzoic Acid. (22) Salicylic Acid. (23) 
 The Lactic-Acid Group. Lactic Acid ; its theoretical Composition, its Tests, 
 its Occurrence in the animal Body, its Origin, and its Uses. (24) Non- 
 nitrogenous resinous Acids. Lithofellic Acid. (25) Cholic Acid. 
 Pettinkofer's Test. (26) Choloidic Acid. (27) Dyslysin. (28) Occur- 
 rence and Mode of Formation of Cholic Acid. (29) Tabular View of the 
 Composition of the Non-nitrogenous Acids . . . . 5 29. 
 
 A 3 
 
VI CONTENTS. 
 
 CHAPTER H. 
 
 NITROGENOUS BASIC BODIES. 
 
 (30) Organic Bases. Volatile Alkaloids. Trymethylamine. (31) Non- 
 volatile Alkaloids. First Group. Their general Formulae. (32) Gly- 
 cine, Sugar of Gelatin, or Glycocoll. (33) Sarcosine. (34) Leucine ; its 
 Appearance under the Microscope ; its chemical Characters ; its Occurrence 
 in the animal Organism ; Lienine and Thymine identical with Leucine. 
 (35) A Body homologous to Leucine. (36) Tyrosine ; its microscopical 
 and chemical Characters; its Occurrence in the animal Organism. (37) 
 Second Group. Their general Formulae. (38) Creatine ; its Occurrence, 
 and its Functions (39) Creatinine. (40) Urea. (41) Its chemical De- 
 compositions and Combinations ; its Tests. (42) Its Occurrence ; its daily 
 Amount ; Influence of Sex, of Food, of Exercise, of Medicines, and of 
 Diseases. Its Presence in the Blood, Fluids of the Eye, &c. (43) Its Origin. 
 (44) Allantoine. (45) Hypoxanthine. (46) Xanthine. (47) Gua- 
 nine (48) Myeline. (49) Cystine. (50) Taurine. <50*) Tabular View 
 of the Composition of the Nitrogenous Bases . . . Pages 30 54. 
 
 CHAPTEE IIL 
 
 NITEOGENOUS CONJUGATED ACIDS. 
 
 (51) Mode of grouping of these Acids. Their theoretical Composition. 
 (52) Hippuric Acid ; its Tests ; its Occurrence ; its Origin. (53) Glycocholic 
 Acid (Strecker's Cholic Acid). (54) Hyocholic Acid. (55) Taurocholic 
 Acid (the Choleie Acid of Strecker and of Demarcay). (56) Inosic Acid. 
 (57) Pneumicor Pulmonic Acid (merely Taurine). (58) Uric Acid ; its 
 chemical Characters and Decomposition, (59) Its Combinations : Urate of 
 Soda ; Urate of Potash ; Urate of Ammonia ; Urate of Lime. (60) Tests 
 for Uric Acid. (61) Its Occurrence in the animal Body ; Chalkstones 
 (62) Its Origin. (63) Cynuric Acid. (t>4) Tabular View of the Composi- 
 tion of the Nitrogenous Conjugated Acids ./. ..;. - jf - . . 55 70. 
 
 CHAPTER IV. 
 
 HALOID BASES AND SALTS, 
 
 (65) Three Groups of Haloid Bases (66) Oxides of Doegling,Cetyl, Cerotyl, 
 and Melissyl. (67) Oxide of Lipyl. (68) Glycerine ; Glycero-phosphoric 
 Acid. (69) The true Fats or Salts of Oxide of Lipyl. (70) Human 
 Fat; Views of Heintz. (71) Stearin. (72) Margarin. (73) Olein. 
 (74) Occurrence of Fat in the animal Body. (75) Origin of Fat. (76) 
 Uses of Fat. (77) Phenylic (or Carbolic) Acid ; Taurylic Acid. (78) The 
 Lipoids. (79) Cholesterin. (80) Castorin and Ambrein. (81) Serolin. 
 
 7183 
 
CONTENTS. vii 
 
 CHAPTEK V. 
 
 THE* CARBO-HYDRATES. 
 
 (82) The Carbo-hydrates occurring in the Animal Organism ; their Formula. 
 (83) Grape-sugar or Glycose ; Saccharates. (84) Trommer's Test for Gly- 
 cose. (85) Moore's Test. (86) Maumene's Test (87) The Fermentation- 
 Test. (88) Occurrence of Sugar (Glycose) in the Animal Organism. 
 
 Artificial Diabetes. (89) Origin of Glycose. (90) Sugar of Milk ; its 
 Occurrence. (91) Inosite or Muscle-sugar ; its Occurrence. (92)Paramy- 
 lon ; Cellulose. (93) Tabular View of the Composition of the Neutral Non- 
 nitrogenous Matters ....... Pages 84 93. 
 
 CHAPTER VI. 
 
 ANIMAL PIGMENTS OR COLOURING MATTERS. 
 
 (94) The Animal Pigments. (95) Hsematin ; its Functions. (96) Hsema- 
 toidin. (97) Bile-pigment (The Cholepyrrhin of Berzelius, the Biliphaein 
 of Simon); its Occurrence, and Origin. (98) Urine-pigment. Urohse- 
 
 matin. Indigo (see also 277) (99) Melanin (99 bis.) Tabular 
 
 View of the Composition of the Animal Pigments . . . 94 100. 
 
 CHAPTER VII. 
 
 THE PROTEIN-BODIES. 
 
 (100) The Protein-bodies occurring in the Animal Organism. Protein. 
 General Characters of the Protein-bodies. Properties of the soluble Protein- 
 bodies ; of the insoluble Protein-bodies. Millon's test. (101) Products 
 of the Decomposition of the Protein-bodies. (102) Albumen ; its Formula ; 
 its Characteristics ; its Tests ; its Occurrence ; its Origin ; its Uses. (103) 
 Fibrin ; its Characteristics ; its Composition ; its Occurrence ; its Origin ; 
 its physiological Importance. (104) Syntonin or Muscle-fibrin. (105) 
 Casein. Means of distinguishing it from alkaline Albuminates, or from 
 acid Solutions of Albumen. Its Occurrence. Its Origin and Uses. 
 (106) Globulin or Crystallin. (107) HEematoerystallin. Tabular View of 
 the ultimate Composition of the Protein bodies . . . 101 118. 
 
 CHAPTER VIII. 
 
 PROXIMATE DERIVATIVES OP THE PROTEIN-BODIES. 
 
 (108) Their general Properties. (109) Ossein. Glutin. (110) Chondrin. 
 (Ill) Elasticin. (112) Fibroin. (113) Chitin. (113*) Tabular View 
 of the ultimate Composition of the proximate Derivatives of the Protein - 
 
 bodies 119124. 
 
 A 4 
 
Vlll CONTENTS. 
 
 CHAPTER IX. 
 
 THE INORGANIC CONSTITUENTS OF THE ANIMAL BODY. 
 
 (114) Inorganic Constituents. Their Division into Three Classes, viz. Sub- 
 stances useful from their Physical Characters ; Substances chemically service- 
 able ; and Substances incidentally present. (115) Substances useful from 
 their Physical Characters. (116) Water. (117) Phosphate of Lime ; its 
 Formula; its Occurrence; its Origin and Formation. (118) Carbonate 
 of Lime; its Occurrence; its Solubility in the Animal Fluids. (119) 
 Phosphate of Magnesia. (120) Fluoride of Calcium. (121) Silicic acid. 
 
 (122) Substances Chemically Serviceable. (123) Hydrochloric Acid. 
 (124) Chloride of Sodium. Its Influence in modifying the Properties of 
 other Substances. Tabular View of the Quantities of Chloride of Sodium in 
 the Animal Fluids. (125) Carbonate of Soda. (126) Phosphates of the 
 Alkalies. Tabular View of the Quantities in which they occur in the 
 Animal Fluids. (127) Ammonia and its Salts. Richardson's Proof of 
 the existence of Ammonia in the Blood. Its Occurrence elsevyhere in the 
 System. (128) Iron. (129) Substances Incidentally present. (130) 
 
 The Sulphates of the Alkalies (131) Carbonate of Magnesia. (132) 
 
 Manganese Arsenic. Copper. Lead. (133) Sulphocyanogen. 
 
 Pages 125139. 
 
 BOOK II. 
 
 THE CHEMISTRY OF THE ANIMAL JUICES AND TISSUES. 
 (134) Classification of the Subject 141 
 
 CHAPTER X. 
 
 THE DIGESTIVE FLUIDS. 
 
 SECTION I. THE SALIVA. (135) The Saliva ; its physical Characters. (136) 
 Parotid Saliva. Ptyalin and its other Constituents. Submaxillary Saliva 
 
 Sublingual Saliva. (137) Buccal Mucus. (138) Chemical Composition 
 of ordinary or mixed Saliva. (139) Incidental and abnormal Constituents ; 
 acid Saliva. (140) Salivary Concretions. (141) Daily Quantity of Saliva. 
 
 (142) The mechanical Uses of the Saliva. (143) Its chemical Uses. 
 
 (144) The Condition of the Salivary Secretion in Infancy (145) Is the 
 
 Action of the Saliva suspended or continued in the Stomach ? (146) Saliva 
 exerts no marked chemical Action on any of the Carbo-hydrates except 
 Starch. (147) Saliva in Rabies 144 157. 
 
CONTENTS. IX 
 
 SECTION II. THE GASTRIC JUICE. (148) The Gastric Juice. Mode of obtain- 
 ing it. (149) Its physical and chemical Characters, and its Composition. 
 
 Its essential Elements. (150) Its free Acid. Difference of Opinion on 
 the Subject. (151) Pepsin. Peptones. Schmidt's Pepsin-hydrochloric 
 Acid. (152) Its mineral Constituents. (153) Abnormal Constituents. 
 (154) Daily Quantity of Gastric Juice. Results yielded by Catherine Kutt. 
 
 (155) Its Function. The Extent of its Solvent Action. (156) Insuffi- 
 ciency of the Gastric Juice to dissolve the necessary Quantity of Nitrogenous 
 Food. (157) Why the Stomach itself is not digested . Pages 158 165. 
 
 SECTION III. THE BILE. (158) Its general Properties. (159) Its essential 
 chemical Constituents : Resinous Acids in Combination with an Alkali, 
 Bile-pigment, and Cholesterin. (160) Differences between Cystic and 
 Hepatic Bile. (161) Abnormal Constituents. Albumen and Urea. 
 Bilifulvin. (162) Gall-stones. (163) Daily Quantity of Bile. (164) 
 Agents influencing the Amount of Bile. (165) Functions of the Bile. 
 (166) Formation of the Bile 166178. 
 
 SECTION IV. PANCREATIC JUICE. (167) Its general Properties. (168) Its 
 chemical Composition. (169) Its daily Amount, (170) Its Functions. 
 
 178182. 
 
 SECTION V. INTESTINAL JUICE. (171) Its physical Properties and chemical 
 Composition. (172) Its Amount. (173) Its Functions . 182 185. 
 
 SECTION VI. THE CONTENTS or THE INTESTINAL CANAL. (174) Subjects 
 included in this Section. (175) The Composition of the semi-solid Con- 
 tents of the small Intestine. (176) The Gases contained in the intestinal 
 Canal. (177) Vomited Matters. (178) The Contents of the fostal In- 
 testine and the Meconium. (179) The Faeces in Health. Their Odour ; 
 their Colour ; their daily Quantity ; their Composition Marcet's Re- 
 searches. (180) Yellow Excrement of Infants. (181) Green Excrements; 
 Causes of the green Colour. Fat, Blood, &c. in the Fseces. (182) The 
 Faeces in Disease. In Typhus ; in Cholera. (183) Intestinal Concretions. 
 
 186200. 
 
 CHAPTER XL 
 
 THE BLOOD AND ITS ALLIES. 
 
 SECTION I. THE BLOOD. (184) Physical Characters of the Blood. (185) 
 Its Coagulation. (186) Its morphotic Constituents. Red and colourless 
 Corpuscles or Cells. (187) The Liquor Sanguinis. The Clot. The 
 Serum. (188) Chemical Composition of the Corpuscles, Liquor Sanguinis, 
 and Blood. (189) General Arrangement of the Subject. (190) The 
 Blood-cells ; their physical Characters ; Variations in their sinking Tendency. 
 (191) Colour of the Blood ; due to several conjoined Causes. (192) Di- 
 chromatism of the Venous Blood. (193) Mode of collecting the Blood-cor- 
 puscles on a Filter. (194) The Cell-membrane of the Red-corpuscles. 
 Best Method of obtaining it. (195) Ratio of the Blood-cells to the Plasma. 
 
X CONTENTS. 
 
 Number of Corpuscles in a given Volume of Human Blood. (196) 
 Chemical Constituents of the Blood-cells. Hacmatocrystallin ; Hsematin ; 
 Fats ; Salts ; Preponderance of Potassium-compounds and Phosphates. 
 
 (197) The Gases of the Blood. The State in which they occur in it. 
 
 (198) The Colourless Corpuscles. The Ratio of the White to the Red 
 Corpuscles. (199) Constituents of the Plasma. (200) The Coagulation 
 of the Fibrin. Different Steps of the Process. (201) Cause of Coagulation. 
 
 (202) Circumstances modifying the Period of Coagulation. (203) Con- 
 sistence of the Clot. (204) Form of the Clot. Buffy Coat. (205) 
 Quantity of Fibrin in the Blood. (206) The Serum. Its occasional 
 Turbidity. (207) The Quantity of Water in the Serum. (208) The Quan- 
 tity of Albumen in the Serum. (209) Is Casein a Constituent of the 
 Blood-serum ? (210) Fats. (211) Extractive Matters. Various known 
 Substances which formerly passed unrecognised amongst the Extractive 
 Matters. (212) Mineral Constituents. (213) Physiological Conditions 
 influencing the Composition of the Blood. Sex. Pregnancy. Age. 
 Digestion. Starvation. (214) Differences between arterial Blood and the 
 Blood of the larger and smaller Veins. (215) Portal Blood. (216) 
 Blood of the Hepatic Veins. (217) Blood of the Splenic Vein. (218) 
 Menstrual Blood. (219) Placental Blood. (220) Influence of Venesec- 
 tion on the Blood. (221) Blood in different Diseases. Inflammatory 
 Diseases. Fevers. Cholera. Dysentery. Bright's Disease. Plethora. 
 
 Anaemia. Chlorosis. Typhus. Puerperal Fever. Pyaemia. Leucae- 
 mia. Carcinoma. Diabetes. (222) Blood of various kinds of Animals. 
 
 (223) Quantity of Blood in the Body. (224) The Functions and ultimate 
 Disintegration of the Blood-cells .... Pages 201 252. 
 
 SECTION H. THE CHYLE. (225) The physical Characters of the Chyle. 
 (226) Its morphotic Elements. (227) Its chemical Constituents. (228) 
 Influence of the Food on its Composition. (229) Quantity of Chyle, 
 
 253256. 
 
 SECTION III. THE LYMPH. (230) The physical Characters of the Lymph. 
 (231) Its morphotic Elements. '(232) Its chemical Constituents and 
 Composition. (233) Quantity of Lymph . . . . 256 257. 
 
 SECTION IV. TRANSUDATIONS. (234) Special Characteristics of Transuda- 
 tions, by which they are distinguished from Secretions and Exudations. 
 (235) Conditions on which Transudation is dependent. (236) Morphotic 
 Elements of Translations. (237) Their Chemical Characters. (238) 
 
 Fibrin. (239) Albumen. The Laws on which its Quantity is dependent. 
 (240) Other Constituents. Casein. Extractive Matters. Cholesterin. 
 Bile-pigment. Sugar. Urea. Creatinine. Organic Acids. Salts. 
 Gases 258266. 
 
 CHAPTER XII. 
 
 THE FLUIDS CONNECTED WITH GENERATION AND DEVELOPMENT. 
 
 SECTION I. THE SEMINAL FLUID. (241) General Characters of the Seminal 
 Fluid. Its morphotic Elements. Effects of various Reagents on the 
 Vitality of the Spermatozoa. Its chemical Composition . 267 269. 
 
CONTENTS. XI 
 
 SECTION II. THE FLUIDS OF THE EGG. (242) The Yelk. Its morphotic 
 Elements and chemical Composition. The White. (243) The Amniotic 
 and Allantoic Fluids in the Chick. The Amniotic Fluid in the Mammalian 
 Ovum. The Allantoic Fluid in the Mammalian Ovum. (244) The (so- 
 called) uterine Milk of the Euro i nan ts . . . . Pages 269 273 
 
 SECTION III. THE MILK. (245) The physical Characters of the Milk. 
 Colostrum-corpuscles. Its Keaction. Its morphotic Elements. (246) Its 
 chemical Constituents. (247) Abnormal Constituents. Albumen; Fibrin; 
 Urea (248) Passage of Matters into the Milk. ("249) The Colostrum. 
 
 (250) Various physiological Influences. Standard of Comparison. 
 
 (251) Milk in Diseases. (252) Milk of Animals. (253) Daily Quantity 
 of Milk. (254) Origin of Milk. Weber's comparative Analysis of the 
 Ashes of Cows' Milk and Ox-blood, showing the Preponderance of 
 Potassium-compounds and Phosphates in the Milk . . 273285 
 
 CHAPTEE XIII. 
 
 THE SECRETIONS OF THE MUCOUS MEMBRANE AND OF THE SKIN. 
 
 SECTION I. Mucus. (255) Mucus. Its physical Properties. (256) Its 
 morphotic Elements. (257) Its chemical Constituents. Mucin. (258) 
 Origin of Mucus .......... 286 289 
 
 SECTION II. SEBACEOUS MATTERS. (259) Sebaceous Matters. Their 
 morphotic Elements. Their chemical Constituents. (260) Castoreum. 
 Secretions of the Cutaneous Glands of certain Eeptiles . . 289 291 
 
 SECTION III. THE SWEAT. (261) The Sweat. Its morphotic Elements 
 and chemical Constituents. Absence of Lactic Acid, and Presence of Urea 
 in the Sweat. (262) The Passage of various Substances into the Sweat. 
 Gases evolved from the Skin. (263) The Amount of Sweat . 292 295 
 
 CHAPTEE XIV. 
 
 THE URINE INCLUDING URINARY SEDIMENTS AND CALCULI. 
 
 (264) The Urine. Its general Properties. (265) Acid and alkaline 
 Fermentation. (266) Its morphotic Elements. (267) Urea. Eesearches 
 of Warncke, Haughton, and Genth, on the Excretion of Urea. Urea in 
 Typhoid Fever ; in Gastric Fever ; in Meningitis ; in Diabetes, (268) Uric 
 Acid. Its daily Quantity. Does it stand in a definite Eatio to the Urea? 
 Influences of Water, of Quinine, and of certain Diseases in modifying the 
 Quantity of Uric Acid. Best Method of determining its Amount. (269) 
 Hippuric Acid. Investigations of Weissmann andllallwachs. Daily Amount 
 of Hippuric Acid. Absence of Hippuric Acid in Jaundice. Origin of 
 Hippuric Acid. Best Method of searching for it in human Urine. (270) 
 Xanthine. Its Eolation to Hypoxanthine. (271) Hypoxanthine. (272) 
 
x ii CONTENTS. 
 
 Allantoine. (273) Creatinine and Creatine. Thtulichum's Observations 
 on their daily Amount. (274) Formic, Lactic, and Butyric Acids. 
 (275) Trymethylamine. (276) Extractive Matters. Researches of Scherer 
 and Hummel, in reference to the Amount excreted at different Ages. 
 Substances included in the term " Extractive Matters." (277) Urine-pig- 
 ments. Schunck's Researches on the Occurrence of Indican (a Substance 
 which yields Indigo Blue) in the Urine. (278) Mineral Constituents of 
 the Urine. Chloride of Sodium. Amount Daily excreted. Influence 
 of Age, Sex, Fasting, salted and non-salted Food, Exercise, copious 
 Water-drinking, Tea, Coffee, Alcohol, &c., on the Excretion of the 
 Chlorides. Diminution of the Chlorides in certain Diseases. Sulphates. 
 The mean Quantity of Sulphuric Acid excreted daily. Circumstances 
 modifying the Amount of excreted Sulphates. Phosphates. Mean daily 
 Quantity of excreted Phosphoric Acid. Circumstances modifying its 
 Amount. Earthy Phosphates. Iron. Silica and Fluorine. (279) 
 Ammonia. Its Occurrence in the Urine disputed. (280) Gases. (281) 
 Water. Great Variations in its quantity. Action of Water on the 
 Urinary Secretion. (282) The free Acid of the Urine. Method of 
 estimating it. Influence of Digestion on the Acidity of the Urine. Re- 
 searches of Bence Jones and Roberts on this Point. Influence of Disease 
 on the Acidity. Connexion between the Acidity of the Urine and the 
 Nature of the Food. (283) Incidental Constituents. Modifications which 
 
 various Substances undergo in their Passage into the Urine (284) Rapidity 
 
 of Elimination. Circumstances modifying it. (285) Abnormal Con- 
 stituents. Albumen. The different Conditions which may cause it to 
 appear in the Urine. Fibrin. Casein. Other Protein-bodies. Fat. 
 Grape-Sugar. Inosite, Leucine, and Tyrosine. Bile-pigment. Biliary 
 
 Acids. Ammonia. Nitric Acid (286) Variations in the Quantity of 
 
 the Urine. Influence of Medicines on the Quantity Influence of Disease. 
 (287) Variations in the Amount of solid Constituents. Daily Quantity of 
 Salts. (288) Influence of various physiological Relations on the Urinary 
 Secretion ; of Sex ; of Age ; of the digestive Process ; of different kinds of 
 Food ; Researches of Lehmann and of Hammond. (289) Urine in Disease. 
 
 Febrile Urine. Anaemic Urine. Difficulties in the Investigation of the 
 Urine in Disease. f290) Urine of Animals. C291) Sketch of the Analysis 
 of the Urine. (292) Tabular View of the daily Urine. (293) Urinary 
 Sediments. Importance of their Study. Urinary Fermentation. Its 
 Effects on the Formation of Sediments. Formation of Uric- Acid Sediments. 
 
 Formation of Phosphatic Sediments. Sediments divisible into un- 
 organised and organised. Unorganised Sediments; Uric Acid ; theUrates ; 
 Conditions under which Sediments of Urates may occur ; Causes occasioning 
 these Sediments ; Hippuric Acid ; Cases in which it occurs as a Sediment ; 
 Oxalate of Lime ; Importance of this Sediment ; earthy Phosphates , Phos- 
 phate of Lime ; Phosphate of Ammonia and Magnesia ; Importance of the 
 Presence of earthy Phosphates as an Evidence of the Alkalinity of Urine ; 
 various Causes of an alkaline Reaction of the Urine ; Cystine Organised 
 Sediments; Mucus and Epithelium ; Pus; Cancerous and Tubercular Matters ; 
 Tubular Casts, occurring (1) as Epithelial Tubes ; (2) as Granular Cylinders, 
 
CONTENTS. Xlll 
 
 and (3) as Hyaline Cylinders. Diagnostic Importance of these Casts and 
 Cylinders; Fungi; Infusoria; Spermatozoa. (294) Tabular Resume of the 
 Sediments. (295) Urinary Concretions; their Constituents. Combustible 
 Calculi ; Uric Acid, Xanthine or Xanthic Oxide, Cystine or Cystic Oxide, 
 Fibrin, Urostealith. Incombustible Calculi ; the Urates, Oxalate of Lime, 
 Carbonate of Lime, Fusible Calculi .... Pages 296 384. 
 
 CHAPTER XV. 
 
 EXUDATIONS. PUS. 
 
 (296) Characteristics of Exudations. Difference between Transudation and 
 Exudation. Cause of their Plasticity. (297) Different Forms of Exuda- 
 tions. Fibrinous plastic Exudation. (298) The Purulent Exudation or Pus. 
 Pus-Corpuscles. Cytoid Corpuscles. Fermentation of Pus. Relations 
 between the Intercellular Fluids of the Blood and of Pus. Action of 
 Chemical Reagents on the Pus- Corpuscles. The Serum of the Pus. Pyin. 
 Ordinary chemical Constituents of Pus .... 385 392. 
 
 CHAPTER XVI. 
 
 THE SOLID TISSUES OF THE BODY. 
 
 (299.) The Osseous System, composed of organic and inorganic Matters. 
 Bone-Cartilage or Ossein. Analysis of different Bones of the Body. The 
 average Composition of Bone. Bones at different Ages. Bones of carni- 
 vorous and herbivorous Mammals, of Birds, of Reptiles, and of Fishes. 
 Morbid Bones. (300) The Teeth. Dentine. Enamel. Cement. 
 Carious Teeth. (301) Cartilage. True Cartilage and Fibro- Cartilage. 
 (302) The horny Tissues. The ultimate Composition of Epidermis, Nails, 
 Horse's Hoof, Hair, and Wool. The Hair. Glycogen in the horny Tissues 
 
 . in foetal Life. Composition and Properties of Glycogen. (303) Muscular 
 Tissue. Smooth Muscle. Its Cell-substance identical with Syntonin. The 
 Characters of the Fluid permeating smooth Muscle. Striped Muscle. 
 Substance forming the Fibrils. Substance of the Nuclei. The Muscular 
 Juice. Its Reaction. Investigation of Du Bois Reymond. Muscular 
 Contraction dependent on the Presence of Oxygen. Physical and chemical 
 Characters of the Muscular Juice. Composition of Muscular Tissue. 
 Glycogen in foetal Muscle. (304) The Brain and Nervous Tissue. Their 
 morphotic Elements. Composition of the Brain. The Brain Fats. The 
 organic and mineral Constituents of the Brain. The relative Proportions of 
 Water, Fat, and Phosphorus in different Parts of the Brain. Action of 
 chemical Reagents on the Nerves. (305) The Glands and their Juices ; 
 their chemical Constituents. Oidtmann's Researches on their inorganic 
 Constituents , 393414 
 
XIV CONTENTS. 
 
 BOOK III. 
 
 THE ZOO-CHEMICAL PROCESSES. 
 
 CHAPTER XVII. 
 
 THE METAMORPHOSES OF THE TISSUES. 
 
 (304) The Four essential Factors in the animal Metamorphoses. (305) 
 Albumen. Its wide Distribution in the animal Body. Proofs of the 
 primary Origin of all the Tissues (excepting perhaps Fatty Tissue) from 
 Albumen or Casein Proofs of the complex Character of the metamorphic 
 Actions going on in the animal Economy. Importance of the inspired 
 Oxygen. Gorup-Besanez's Researches on the Action of Ozonised Air on 
 Solutions of Albumen and Casein. (306) The Fats. Their various uses 
 in relation to Cell-formation. Changes which the Fat in the Blood under- 
 goes. Evidence that the Fats are not mere Materials for Combustion. 
 Does the Organism possess the Power of converting the Protein-Bodies into 
 Fat? Investigations to determine this Point. (307) The Carbo-hydrates. 
 Uses of the Sugars and other Carbo-hydrates through their acid Pro- 
 ducts of Metamorphosis Formation of acid Phosphates. Sugar as a 
 
 Solvent. Formation of Fat from Sugar. (308) Mineral Constituents. 
 Antagonism of acid and alkaline Fluids. Acid Phosphates and Potash 
 Salts. Alkalinity of the Blood. Uses of the Alkalies in the Blood. 
 Oxidising Action of Alkalies on Sugar, on the Fats and Fatty Acids, on 
 Haematin, and on the albuminous Matters of the Blood. Oxidising Action 
 of the Blood. Co -existence of an oxidising and a de-oxidising Process. 
 Chloride of Sodium an active metamorphic Factor. Observations of 
 Boussingault on the Use of Salt. Different Modes in which it acts. 
 
 Pages 417-435 
 
 CHAPTER XVIII. 
 
 DIGESTION. 
 
 (309) Digestion of mineral Substances. (310) Digestion of the Carbo- 
 hydrates. Digestion of Grape-Sngar. Laws of its Absorption. Behaviour 
 of Cane-Sugar and Sugar of Milk in the intestinal Canal. (311) Digestion 
 of Starch. (312) Opinions and Experiments on the Digestion of Gum. 
 (313) Digestion of Cellulose. (314) Digestion and Absorption of Fats. 
 
 (315) Discussion regarding the Digestion and Absorption of Alcohol. 
 
 (316) Protein- Bodies and their Allies; the Changes which they undergo in 
 the intestinal Canal Peptones. Parapeptones. (317) Changes which 
 
CONTENTS. XV 
 
 Emulsin, Curarine, &c., undergo in the Intestinal Canal. (318) The 
 various intestinal solvent Fluids. Discussion regarding the Action of 
 the Pancreatic Juice on the Albuminates. (319) Absorption of the 
 Peptones. (320) Daily Amount of intestinal Fluids. (321) Busch's Ob- 
 servations on a Woman with a Fistula in the Jejunum. Experiments on 
 the Digestibility of Food Pages 436 456. 
 
 CHAPTER XIX, 
 
 RESPIRATION. 
 
 (322) Nature of the Respiratory Process. (323) Ratio of the inspired 
 Oxygen to the exhaled Carbonic Acid. (324) Volume of the expired 
 Air. Amount of exhaled aqueous Vapour. Variations in the in- 
 haled and exhaled Nitrogen. Volatile Matters in the expired Air. 
 (325) Percentage of Carbonic Acid in the exhaled Air. Amount of 
 Oxygen that is retained daily in the System. (326) Influence of the 
 Rapidity of the Respiration on the Amount of Carbonic Acid. Influence of 
 
 the Depth of the Respiration (327) Excess of Carbonic Acid in the last 
 
 Part of an Expiration. (328) Influence of partial Suspension of the Re- 
 spiration (329) Influence of artificial Atmospheres; of Excess of Oxygen; 
 of Excess of Carbonic Acid ; of Excess of Nitrogen ; of Nitrous Oxide ; of 
 Hydrogen ; of Carbonic Oxide. (330) Atmospheric Influences. Tempe- 
 rature; Moisture; Atmospheric Pressure; Periods of the Day; Periods of 
 the Year. (331) Internal Conditions of the Organism. Abstinence. 
 (332) Influence of the Chemical Nature of the Food. Chemical Explanation 
 of the Results. Dr. E. Smith's researches on the subject. (333) In- 
 fluence of the Quantity of Food. (334) Influence of Alcohol, Tea, and 
 Coffee. (335) Influence of Sleep ; of Hybernation ; of Exercise; of Age; of 
 Sex. (336) Tabular View of the normal Relations of Carbonic Acid. 
 (337) Respiration in Animals. (338) Respiration in Disease. (339) 
 Origin of the Carbonic Acid. (340) Animal Heat . . 457486. 
 
 CHAPTER XX. 
 
 NUTRITION. 
 
 (341) Investigations preliminary to that of Nutrition. (342) Necessity of an 
 Admixture of the different Kinds of Food in certain Proportions. Inves- 
 tigations of Dr. Hammond on the nutritive Value of Albumen, Starch, and 
 Gum, when taken singly and exclusively. (342) Digestibility as an Ele- 
 ment of the nutritive Value. (343) Nitrogen as a Measure of the nu- 
 trient Value. Liebig's Table of the Proportions between the Albuminates 
 and the non-nitrogenous nutrient Matters in the most common Articles of 
 Food. (344). The best relative Admixture of the different Groups of 
 Food. (345) The necessary Quantity of Food; Method of determining 
 it. Play fair's Tables. Vierordt's Calculations. (346) Quantity of Food 
 
XVI CONTENTS. 
 
 that can be absorbed in a given Time. (347) Influence of different Kinds 
 of Food on the Composition of the Blood. (348) Distribution of the final 
 Products of the Food in the Excretions. (349) Metamorphosis of the 
 Tissues during Inanition. (350) Effect of the entire Abstraction of Water. 
 
 (351) The intestinal Juice as a Measure of the Metamorphosis (352) 
 
 On the Power which certain Substances exert in checking the Metamor- 
 phosis of the Tissues. The physiological Action of Alcohol, of Tobacco, 
 of Tea, and of Coffee - . Pages 487 517. 
 
 EXPLANATION OF THE PLATES 518 526. 
 
 CORRECTIONS AND ADDITIONS. 
 
 Page 16. Last line. For " Plate I. fig. 3.," read " Plate I. fig. 5." 
 47. Second note. Stadeler has repeated Bechamp's experiments, and 
 denies that urea can be formed from albumen by the action of per- 
 manganate of potash ; he believes that benzoic acid, which is really 
 formed, was mistaken for urea. 
 98. Note. For " Scherer," read " Sicherer." 
 423. Note. For " Hippert," read " Huppert." 
 
PHYSIOLOGICAL CHEMISTRY, 
 
 INTEODUCTION. 
 
 (1.) THE object of PHYSIOLOGICAL CHEMISTRY is to elucidate Physio- 
 the chemical phenomena attending the vital processes. Chemistry 
 
 In order to understand these processes, we must have clear 
 conceptions of what may be termed the organic substrata of 
 the animal body ; that is to say, we must acquaint ourselves 
 both with the chemical and with the physiological relations 
 of every body or substance occurring in the organism. 
 
 The chemical relations of a substance have reference to its Chemical 
 general properties, its actual composition (as determined by substances, 
 analysis) and its rational formula, its most important com- 
 binations, the products of its metamorphosis, the method of 
 obtaining it in a state of purity, and its tests : while the 
 physiological relations have reference to the fluids or tissues Physio- 
 in which it occurs, to the quantity in which it exists, to its 
 origin (whether it be actually produced within the body or 
 introduced from without), and to its uses in the animal 
 economy. In this volume I have entered much more fully 
 into the physiological than into the chemical relations ; and I 
 have been led to adopt this course because there are now 
 several excellent manuals*, accessible to every student, in 
 which all the necessary information relating to the purely 
 chemical details is sufficiently given. 
 
 * Perhaps I may especially indicate Gregory's " Handbook of Organic 
 Chemistry," 4th ed. London, 1856. 
 
 B 
 
2 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Chemistry 
 of the ani- 
 mal fluids 
 and solids. 
 
 Zoo-che- 
 mical pro- 
 cesses. 
 
 Division of 
 the subject. 
 
 Having thus familiarised ourselves with the individual proxi- 
 mate elements of which the body is composed, we next pro- 
 ceed to consider them in reference to their simultaneous 
 occurrence, and to their admixture in the form of animal 
 juices and tissues. The knowledge of the chemical composition 
 of these varying and complex parts of the body is obviously 
 another and a more advanced basis of physiological chemistry, 
 for it is evident that we cannot satisfactorily treat of the 
 great chemico-vital processes without a knowledge of the 
 substances implicated in them ; but this investigation is 
 attended with far greater difficulties than the study of the 
 organic substrata, for here we have to deal for the most part 
 with complicated mechanical mixtures whose separation is 
 often an impossibility. The microscope here affords us very 
 useful assistance. It has contributed most materially to our 
 knowledge of those animal fluids which contain morphotic 
 elements (as, for instance, blood, milk, semen, pus, &c.), and of 
 all the solid tissues of the body, as may be seen by a reference 
 to almost every page of the Chapter on Histochemistry. In 
 this division of the volume especial reference has been made 
 to the quantities in which the various glandular products are 
 secreted, a point to which little attention had been paid until 
 the last few years, although the importance of such numerical 
 data, in reference to the general metamorphosis of the tissues, 
 now seems too obvious to require comment. 
 
 The organic substrata of the animal body, and the constitution 
 and functions of the animal juices and tissues, having been 
 duly considered, we are now prepared to enter upon the highest 
 and most important part of our subject, namely, the study of 
 the great zoo-chemical processes, under which we include the 
 metamorphosis of tissue, digestion, respiration, and nutrition. 
 
 Hence the subject-matter of this volume naturally divides 
 itself into three great heads or departments : 
 
 1. The organic substrata of the animal body. 
 
 2. The chemistry of the animal juices and tissues. 
 
 3. The great zoo-chemical processes. 
 
BOOK I, 
 
 THE 
 
 ORGANIC SUBSTRATA OF THE ANIMAL BODY; 
 
 OB 
 
 THE PROXIMATE PRINCIPLES ENTERING INTO THE 
 
 COMPOSITION OF THE SOLIDS AND FLUIDS 
 
 OF THE ORGANISM. 
 
CHAPTER I. 
 THE NON-NITROGENOUS ORGANIC ACIDS, 
 
 (2.) IN the following sketch of the zoo-chemical elements, 
 we shall adopt the principle of a purely chemical arrange- 
 ment ; that is to say, we shall retain those groups that have 
 been established by the most recent investigations of pure 
 chemistry ; but as the physiological importance of a body is 
 always in accordance with its chemical composition, it follows 
 that substances of homologous chemical value must always 
 possess common physiological relations ; and that hence our 
 arrangement may at the same time be regarded as a phy- 
 siological one. 
 
 The first great class of substances which we shall describe 
 are the non-nitrogenous organic acids, which may be arranged 
 in the following manner : 
 
 1. Fatty acids with the general formula C 2n H 2n _i0 3 . HO. 
 
 2. The succinic-acid group . C n H n _ 2 3 . HO. 
 
 3. The oleic-acid group . . . C2nH 2n _ 3 3 . HO. 
 
 4. The benzoic-acid group . . . C n H n _ 9 3 . HO. 
 
 5. The lactic-acid group .... C 2n H 2n _ 1 5 . HO. 
 
 6. The non-nitrogenous resinous acids. 
 
 We thus commence with bodies of the simplest composi- 
 tion, some of which are probably not actually developed in 
 the living organism ; but with which it is necessary that we 
 should be acquainted, as being the derivatives of animal sub- 
 stances. From these groups of comparatively simple bodies 
 we shall gradually pass to those of a more complicated com- 
 position to the nitrogenous basic and neutral bodies, to 
 
 B 3 
 
~ </,, PHYSIOLOGICAL CHEMISTRY. 
 
 nitrogenous conjugated acids, to the haloid bases and lipoids, 
 to the carbo-hydrates, to the animal pigments, and to the 
 histogenetic (or tissue-building) substances while we shall 
 conclude this portion of the work with a notice of the mineral 
 constituents of the animal body. 
 
 FATTY ACIDS. 
 
 C 2n H 2n _ 1 3 .HO. 
 
 Fatty acids. The first great group to be considered is that of the Fatty 
 Acids. 
 
 There is a perfect and continuous series of these acids 
 known, from n = 1 to n=18; but the only ones that at 
 present concern us are : 
 
 Formic acid . . . = C 2 H 3 .HO. 
 
 Acetic acid . . . = C 4 H 3 3 . HO. 
 
 Metacetonic acid . . = C 6 H 5 3 . HO. 
 
 Butyric acid . . . = C 8 H 7 3 . HO. 
 
 Valerianic acid . . = C 10 H 9 3 . HO. 
 
 Caproicacid. . . = C 12 H n 3 . HO. 
 
 Caprylicacid. . . = C 16 H 15 3 . HO. 
 
 Capricacid . . . = C 20 H 19 3 . HO. 
 
 Oocicacid . . . = C K H M 9 . HO. 
 
 Myristicacid. . . = C 28 H 27 3 . HO. 
 
 Palmitic acid .' . = C 32 H 31 3 . HO. 
 
 Margaricacid . . = C 34 H 33 3 . HO. 
 
 Stearicacid . . . = C 36 H 35 3 . HO. 
 
 The acids at the two extremes of the group differ very con- 
 siderably, both in their physical and chemical characters, and 
 consequently also in their physiological importance, notwith- 
 standing the general analogies that subsist throughout the whole 
 of them : and hence we separate this series somewhat arbi- 
 trarily into two groups, the first extending as far downwards 
 as capric acid, and known as the volatile fatty acids ; while 
 the remaining members are designated the solid fatty acids. 
 
OXALIC ACID. 7 
 
 There is good reason for believing that the volatile fatty Theoreti- 
 acids are conjugated oxalic acids* ; that is to say, that they are sitionoV 
 acids in which oxalic acid, C 2 3 + HO, is so combined with a 
 carbo-hydrogen, C 2n H 2 n + 19 as not to affect its own saturating 
 capacity : and on the assumption that oxalic acid constitutes 
 the acidifying principle of the acids of this group, we shall 
 consider it first in the series of acids. 
 
 (3.) Oxalic acid^ never occurs in the animal organism, ex- Oxalic 
 cept in combination with lime. Oxalate of lime, CaO.C 2 3 , 
 occurs in various animal fluids as a white powder, which Oxalate of 
 under the microscope exhibits a distinct crystalline form. 
 When seen with a comparatively low power, these crystals 
 present the appearance of a square envelope ; but, when more 
 highly magnified, they may be seen to be octohedrons. (See 
 Plate I. Jig. 1.) They are insoluble in hot water, in acetic 
 acid, oxalic acid, and in ammonia, but dissolve readily in the 
 stronger mineral acids. Crystals of this salt cannot be con- 
 founded with those of chloride of sodium, which often re- 
 semble them in form, if we recollect that the latter are very 
 soluble in water. Large crystals of oxalate of lime occa- 
 sionally present some similarity to crystals of phosphate of 
 ammonia and magnesia, but a careful microscopical examina- 
 tion, and the solubility of the latter salt in acetic acid, will 
 readily decide the question. It is still uncertain whether the 
 dumb-bell crystals occasionally found in the urine consist of 
 oxalate of lime, as was originally supposed, as both carbonate 
 of lime and uric acid may assume this form. (See Plate Lfig. 2.) 
 
 When oxalate of lime occurs as a constituent of an urinary 
 calculus, its crystalline character is lost, andr we cannot apply 
 the microscope to its detection. The following simple test 
 may then be employed. On the application of strong heat to 
 a fragment of the calculus, carbonic oxide is given off, and it 
 becomes converted without charring into carbonate of lime, 
 
 * Lehmann's Phys. Chem. (Cavendish Society's Translation), vol. i. p. 39. 
 f The per-centage composition of this and the other non-nitrogenous acids 
 is given in a table at the end of the chapter. 
 
 B 4 
 
8 PHYSIOLOGICAL CHEMISTRY. 
 
 and ultimately, if the heat be sufficiently prolonged, into 
 quicklime. 
 
 Oxalate of lime can be separated from most of the sub- 
 stances with which it is likely to be mixed, by acetic acid or a 
 dilute solution of potash, in neither of which is it soluble. 
 
 Oxalate of lime is so frequently found in small quantity 
 in apparently healthy urine, that we can hardly regard it as 
 an abnormal constituent of that fluid. The physiological and 
 pathological relations under which it occurs in augmented 
 quantity will be subsequently described when we treat of 
 the morbid conditions of the urine. It is, moreover, often 
 found in urine which has stood for some time, and in which 
 acid urinary fermentation has taken place, when the. perfectly 
 fresh urine presented no trace of it. It has likewise been 
 found in morbid blood ; it is often present in the mucus of the 
 gall-bladder, and is scarcely ever absent from the mucous 
 membrane of the impregnated uterus. It is rarely found in 
 the excrements (only after the use of vegetables containing 
 oxalic acid.) 
 
 The origin of the oxalate of lime found in these cases may 
 be referred to several sources. As the use of vegetable food, 
 especially such as contains oxalates, increases the quantity of 
 oxalate of lime in the urine, we may fairly infer that the 
 oxalic acid is transmitted from the food to the urine. Since, 
 however, the vegetable alkaline salts which abound in plants 
 also increase the oxalate of lime in the urine, we must not 
 refer the augmentation to the former source alone. A well- 
 marked increased excretion of this salt is also observed after 
 the use of drinks rich in carbonic acid, of alkaline bicarbonates, 
 and in short of everything that can overload the blood with 
 carbonic acid ; and this is in accordance with another well- 
 established fact, that wherever the respiratory process is 
 affected, or the metamorphosis of the tissues is deranged (an 
 accumulation of carbonic acid in the blood being the result in 
 either case), oxalate of lime may always be found more or less 
 
YOLATILE FATTY ACIDS. 
 
 abundantly in the urine : thus it has been observed in pul- 
 monary emphysema, in the convalescent stage of typhus, &c. 
 
 Since the discovery that uric acid can be decomposed by an 
 oxidising agent (peroxide of lead) into urea, allantoine, and 
 oxalic acid, it has been commonly assumed that the oxalic 
 acid of the urine is due to an oxidation of the uric acid, the 
 oxalic acid in this case not being further oxidised into car- 
 bonic acid, as usually occurs in the healthy organism ; and 
 this view is strongly confirmed by the experiments of Wohler 
 and Frerichs*, who have shown, by direct experiments, that 
 urates, injected into the veins of dogs, or mixed with the 
 food of men, largely increase both the urea and the oxalate of 
 lime in the urine ; and by the observations of Neubauerf, who 
 obtained a similar result when uric acid was introduced into 
 the stomachs of rabbits. 
 
 In the great majority of cases the latter is the most pro- 
 bable mode of accounting for the presence of this acid, which 
 we must thus regard as due to the imperfect oxidation of uric 
 acid, and probably of other organic substances in the blood. 
 It must always be regarded as a final product of excretion. 
 
 VOLATILE FATTY ACIDS. 
 
 (4.) The following are the general characters of these acids. Chemical 
 They are liquid, or at all events fusible, at a temperature not c aracters * 
 exceeding 86, and do not solidify and crystallise till it is re- 
 duced below the freezing point. They are so volatile that at 
 an ordinary temperature their vapour is extremely irritating to 
 the eyes and nostrils. They can be distilled without decom- 
 position, and boil at a temperature which stands in a definite 
 ratio to the number of atoms of carbo-hydrogen, the boiling 
 point rising by rather more than 34 for every two atoms of 
 CH. They are soluble in water, alcohol, and ether, but their 
 solubility in water diminishes as their amount of carbon in- 
 
 * Ann. d. Ch. u. Pharm. 1848, vol. Ixv. p. 340. 
 t Ibid. 1856, vol. xcix. p. 206. 
 
10 PHYSIOLOGICAL CHEMISTRY. 
 
 creases. They redden litmus powerfully, and unite with bases 
 to form salts, most of which are soluble in water and crys- 
 tallisable ; as, however, in the case of the acids, the solubility 
 decreases as the carbon increases, and hence the salts of capric 
 acid are the least soluble. 
 
 The first two acids of this group, formic and acetic acid, are 
 the most powerful ; strictly speaking they have no right to be 
 called oily or fatty. As the number of atoms of CH increases, 
 the acids become by degrees less energetic, but assume the 
 character of oils, and finally of fats. Metacetonic acid is 
 only slightly oily ; capric acid is a solid fat. 
 
 Tests for As there are great difficulties in determining quantitatively, 
 faTty acids 6 anc ^ m some cases even qualitatively, the presence of these 
 volatile fatty acids, we shall merely notice such tests and re- 
 agents as can without much danger of fallacy be applied by 
 a student ordinarily versed in chemistry. 
 
 To detect these acids in an animal fluid we must first 
 isolate them. The following are the general steps of the 
 process to be adopted. We place the fluid in a retort, add a 
 few drops of strong sulphuric acid to liberate them from the 
 bases with which they are combined, and distil. The distillate, 
 which is usually only faintly acid and somewhat opalescent, 
 is saturated with carbonate of soda, evaporated on a water-bath, 
 and redistilled with a little dilute sulphuric acid, without the 
 application of heat. If several acids of this group are simul- 
 taneously present, they may be separated by fractional distil- 
 lation ; formic acid, from its boiling point being the lowest, 
 comes over first, and the others in succession according to 
 their boiling points. 
 
 a. Formic acid may be distinguished from the other acids 
 of this group, by its power of reducing the oxides of silver and 
 mercury. 
 
 b. Acetic acid resembles formic acid, and in this respect, 
 also, meconic and hydrosulphocyanic acids, in producing an 
 intense red colour with perchloride of iron; but it may at 
 
VOLATILE FATTY ACIDS. 11 
 
 once be distinguished from formic acid, by its not having the 
 power of reducing the oxides of silver or mercury. If there 
 should be any possibility of the presence of either of the two 
 other acids, it may readily be distinguished from meconic acid 
 by the solubility of the acetate of lime (the meconate of lime 
 being insoluble in water), and from hydrosulphocyanic acid 
 by the circumstance that the red solution of sulphocyanide of 
 iron, if boiled with a little ferrocyanide of potassium, very 
 soon precipitates Prussian blue, which is not the case with 
 the acetate of the peroxide of iron. 
 
 c. The odour of several of these acids (e. g. acetic, vale- 
 rianic, and butyric acids) is sufficiently characteristic to be 
 ranked amongst the tests. 
 
 d. The presence of metacetonic acid can only be ascertained 
 with certainty by the elementary analysis of one of its salts, 
 or by the determination of the atomic weight or saturating 
 capacity; and the same observation equally applies to the 
 other acids of this group. 
 
 (5.) As its name indicates, Formic acid occurs in ants Formic 
 (especially Formica rufd) ; Will has recently shown that the acid ' 
 active poisonous principle in certain caterpillars is formic 
 acid, and it is highly probable that the irritation caused by 
 the stings of various insects is due to this acid ; Scherer has 
 found it in association with other acids of this group, in the 
 muscular and splenic juices, and in leucaemic blood ; Campbell 
 has found it in the blood, urine, and vomited matters; and 
 Schottin has proved that it is by far the chief of the volatile 
 constituents of the sweat; and Grorup-Besanez has found it 
 in considerable quantity in the thymus gland. 
 
 (6.) Acetic acid was found by Scherer, in association with Acetic 
 formic acid, in the muscular and splenic juices, and in leu- 
 caemic blood, and by Grorup-Besanez in the juice of the thymus 
 gland ; Lehmann and others have found it in the gastric juice 
 in cases of impaired digestion ; and Schottin has proved that 
 it is a constant ingredient both of normal and morbid sweat. 
 
12 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Meta- 
 
 cctonic 
 
 acid. 
 
 Butyric 
 acid. 
 
 Valerianic 
 acid. 
 
 Caproic, 
 caprylic, 
 and capric 
 acids. 
 
 Their 
 origin. 
 
 (7.) As Metacetonic acid is readily formed in the laboratory 
 during the oxidation both of the fats and of the albuminous 
 bodies, there is no apparent reason why it should not occur in 
 the animal organism. Schottin thinks that he has found it 
 in sweat. 
 
 (8.) Butyric acid has been found by Scherer in the muscular 
 and splenic juices, and by Lehmann in the juice of the mus- 
 cular coat of the stomach. Salts of this acid have not yet 
 been discovered in the blood, although they probably exist 
 there. It occurs in a free state in the sweat, although in less 
 quantity than formic or acetic acid. The milk contains, in 
 addition to other fats, as margarin and olein, one which on 
 saponification yields butyric acid, together with caproic, ca- 
 prylic, and capric acids. This acid has been found in the 
 human gastric fluid by Gruenewaldt, but Frerichs had pre- 
 viously observed that after the use of amylaceous food there 
 is often a strong odour of butyric acid in the contents of the 
 lower part of the ileum and of the colon ; Eagsky and Percy 
 have, moreover, discovered it in the faeces. 
 
 (9.) Valerianic acid in association with leucine has been 
 found in the urine in typhus fever by Frerichs ; this leucine 
 had probably undergone a partial decomposition into valeria- 
 nate of ammonia. See 31. 
 
 (10.) As Caproic, Caprylic, and Capric acids, in combina- 
 tion with glycerine or oxide of lipyl, exist in the milk, it is 
 most probable that they also occur in the blood. From the 
 peculiar odour of the sweat it is very likely that one or 
 more of these acids are present in minute quantity in it. 
 
 (11.) As most of the above named acids have been arti- 
 ficially obtained in the laboratory by the oxidation of the 
 fats and albuminous bodies, and as the most essential pro- 
 cesses in the living organism are based on a process of oxida- 
 tion, the presence of the volatile fatty acids in the animal 
 fluids is thus readily accounted for. From Schottin's observa- 
 tions on the sweat, their formation seems to be increased, as 
 
VOLATILE FATTY ACIDS. 13 
 
 is also the case with oxalic acid, when the respiratory process, 
 and, consequently, the general oxidation of the system, is 
 impeded. In some cases, however, the acid may be directly 
 introduced from without ; thus, it is by no means certain that 
 the ants actually produce formic acid, for we know that it is 
 contained in juniper and other berries, and in fir-cones, which 
 are much sought after by these insects : and in other cases, 
 especially in that of butyric acid, it is extremely probable 
 that the fatty acid is formed in the lower portion of the * 
 intestinal canal from carbo-hydrates taken as food, all the 
 necessary conditions for the development of this kind of fer- 
 mentation being usually present there. 
 
 Heintz* has made an experiment which seems to prove 
 that the acids found by Scherer in the muscular juice do not 
 pre-exist there, but must have been mere products of the 
 decomposition of the flesh that ensued during his operations. 
 He failed in obtaining any trace of a volatile fatty acid from 
 50 pounds of horse-flesh. 
 
 (12.) From the preceding remarks on the occurrence of Their uses, 
 these acids, we are justified in believing that they play no 
 very important part in the animal economy. When occurring 
 in the stomach and intestinal canal, they must be regarded 
 as mere incidental substances due to the temporary establish- 
 ment of a special fermentative process ; and their presence in 
 the two great depurating fluids, the sweat and the urine, 
 clearly indicates that they are true products of excretion. 
 They must therefore be classed amongst the products of the 
 regressive metamorphosis of tissue ; that is to say, they 
 originate from those changes which the tissues and juices 
 undergo in the discharge of their physiological functions. In 
 the perfectly healthy state they, for the most part, undergo 
 further oxidation, and are finally excreted in the form of car- 
 bonic acid and water ; but when, from the establishment of 
 
 * Lehrbuch der Zoochemie, Berlin, 1853, p. 447. 
 
14 PHYSIOLOGICAL CHEMISTRY. 
 
 any morbid process, the normal oxidation of the blood is 
 impeded, these substances are found in increased quantity in 
 the excretions. 
 
 SOLID FATTY ACIDS. 
 
 (13.) These acids are distinguished from those which have 
 just been considered by the following properties : At an ordi- 
 nary temperature they are solid, white, and crystalline, are 
 devoid of odour or taste, make a persistent greasy spot on 
 paper, and for the most part cannot be submitted to ordinary 
 distillation without decomposition. They are perfectly in- 
 soluble in water, dissolve in boiling alcohol, from which they 
 separate in a crystalline form on cooling, and are readily 
 soluble in ether. Their alcoholic solutions only faintly redden 
 litmus. They unite with most bases, and form insoluble 
 salts, their alkaline salts the soaps being alone soluble in 
 water. 
 
 (14.) The following properties of Margaric and Stearic acids, 
 the most important bodies of this class, may assist in their 
 identification. Margaric acid* separates from a hot alcoholic 
 solution in glistening groups of very delicate needles, which 
 under the microscope appear in variously sized grass-like 
 bunches of ensiform or lily-leaf-shaped crystals, or in star-like 
 forms (Plate /., Jig. 3.); while stearic acid crystallises in 
 white glistening needles or leaflets, which when magnified 
 appear as very elongated lozenge-shaped laminae, with the 
 obtuse angles rounded off, as in the whetstone-like crystals 
 of uric acid (Plate L, fig. 4.) ; these crystals are, however, 
 much longer, and have a far shorter transverse diameter than 
 the corresponding crystals of uric acid ; they often collect at 
 one spot, and present the appearance of whorl-shaped clusters, 
 the acute angles slightly overlapping one another. 
 
 Their fusing points are 133 and 167 respectively. As the 
 two acids are commonly associated together, Gottlieb has 
 
SOLID FATTY ACIDS. 15 
 
 determined the fusing points of their mixtures in various 
 proportions. His table is given in Lehmann's " Physiological 
 Chemistry," vol. i. p. 111., and may serve to assist in an ap- 
 proximate determination of the ratios in which they occur. 
 
 Heintz, in one of his latest memoirs * on the fats and fatty 
 acids, denies the existence of margaric acid, and maintains 
 that it is a mixture of about ten parts of palmitic acid with 
 one part of stearic acid. This view is, however, not generally 
 adopted. 
 
 The recent researches of Heintz show that the following Other solid 
 acids of this sub-group occur in the animal economy. 
 
 Code, Myristic, and Cetic acids have been detected by 
 himf, in spermaceti, in combination with ethal (or hydrated 
 oxide of cetyl). See 66. 
 
 Palmitic aczdhas been found by the same chemistj (but by 
 no one else) in human fat, in mutton suet, and in spermaceti. 
 
 (15.) Margaric acid occurs either in a free state or in com- Their oc- 
 bination with alkalies, in most of the animal fluids, with the currencc - 
 exception of the urine; being free in acid fluids, and in a 
 state of combination in those with an alkaline reaction. It is 
 always accompanied by oleic acid or oleates. Free margaric 
 acid is chiefly found in acid pus, in the fluid of ovarian 
 dropsy, and in the excrements after the use of vegetable food 
 or of purgative medicines ; while alkaline margarates occur in 
 the blood, chyle, saliva, exudations, and most abundantly in 
 the bile and in ordinary pus. 
 
 In combination with oxide of lipyl (see 72.) this acid 
 forms margarin, the most widely diffused of all the anima 
 fats. 
 
 Stearic acid never occurs free or in combination with the 
 alkalies, unless in association with margaric acid. Like 
 margaric acid, it unites with oxide of lipyl to form stearin, 
 which almost always accompanies margarin. 
 
 * Pogg. Annal. vol. Ixxxvii. p. 553 ; or Lehrb. d. Zoochem. p. 1074. 
 f Lehrb. d. Zoochem. p. 489. J Ibid. p. 428. 
 
16 PHYSIOLOGICAL CHEMISTRY. 
 
 We shall postpone our observations on the origin and im- 
 portance of these acids, till we treat of the fats in which they 
 mainly occur. (See 75 and 76.) 
 
 THE SUCCINIC-ACID GROUP. 
 
 C n H n _ 2 3 -HO. 
 
 (16.) Only one of the acids of this group, namely succinic 
 acid, has as yet ever been detected in the animal organism ; 
 the other acids, namely, lipic, adipic, pimelic, suberic, and se- 
 bacic acids, are only of interest in zoo-chemistry, in so far as, 
 like many of the acids of the preceding group, they are pro- 
 ducts of decomposition of many animal substances, and 
 especially of the fats. They are probably, like the last group, 
 conjugated oxalic acids. 
 
 Succinic acid is represented by the formula C 4 H 2 3 .HO, or> 
 according to the above hypothesis, by (C 2 H 2 ) C 2 3 .HO. It is 
 of such rare occurrence that it is unnecessary to enter into any 
 chemical details regarding it. It was once found by Heintz * 
 in the fluid contents of hydatids in the liver, where it has 
 been re-discovered by Bodekerf; and it has recently been de- 
 tected by Grorup-BesanezJ, in the thymus gland of calves and 
 in the spleen and thyroid gland of oxen, and, by W. Muller, 
 in the fluid of hydrocele. 
 
 Sebacic acid, which is represented by the formula C 10 H 8 3 . 
 HO, or as a conjugated acid by (C 8 H 8 ) C 2 3 .HO, is deserving 
 of notice, as being only formed during the dry distillation 
 of oleic acid. Hence we may determine the presence and 
 amount of olein in a fat, from the presence and amount of the 
 sebacic acid. It crystallises in whorled clusters, similar to 
 margaric acid, or in laminae radiating from a centre. (See 
 Plate I. fig. ^ 
 
 * Op. cit. p. 228. 
 
 f Zeitsch. f. rat. Med. 1855, vol. vii. p. 137. 
 
 f Ann. d. Ch. u. Pharm. 1856, vol. xcviii. p. 40. 
 
 Zeitsch. f. rat. Med. 1856, vol. viii. p. 130. 
 
OLEIC ACID. 17 
 
 THE OLEIOACID GROUP. 
 
 (17.) The acids of this group requiring notice, are 
 
 Damaluric acid . . . C 14 H H 3 .HO. 
 
 Damolic acid . . . C 26 H 23 3 .HO. 
 
 Oleicacid .... C 36 H 33 3 .H(X 
 
 and Doeglingic acid . ^. . C 38 H 35 3 .HO. 
 
 The first two of these are oily volatile fluids which are 
 slightly soluble in water, but dissolve freely in alcohol and 
 ether, and redden litmus ; they may be regarded as standing 
 to the two other acids in much the same relation as the 
 volatile to the solid fatty acids. 
 
 The last two exist at an ordinary temperature as oily fluids, 
 and in most of their physical, and in many of their chemical 
 properties, resemble the solid fatty acids. 
 
 (18.) Damaluric and Damolic acids were discovered by Damaluric 
 Stadeler amongst the products of distillation of the urine of mo iic acids. 
 the cow, and of man. As they have not as yet been disco- 
 vered in any other fluid, and occur in very minute quantity, 
 they present little physiological interest. 
 
 (19.) Oleic acid, when perfectly pure, and at a temperature Oleic acid. 
 above 57, is a limpid oily fluid, devoid of taste and smell, 
 and exerting no action on litmus ; at 39 it solidifies into a 
 hard, white, crystalline mass. When heated it becomes de- 
 composed, and yields on dry distillation not only carbon, 
 carbonic acid, and carbo-hydrogens, but capric and caprylic 
 acids, and sebacic acid. It possesses the distinctive character 
 of being the only substance which on dry distillation yields 
 the last-named acid, which we may readily distinguish from 
 the simultaneously formed capric and caprylic acids, by the 
 shape and arrangement of its crystals. 
 
 Oleic acid is invariably found wherever margaric and Its occur- 
 stearic acids occur ; in the blood and in the bile it is com- 
 
18 PHYSIOLOGICAL CHEMISTRY. 
 
 bined with alkalies ; it is found free in acid pus ; and it is 
 combined with oxide of lipyl, forming olein, in the subcu- 
 taneous adipose tissue, and indeed wherever free fat occurs 
 in the animal body. 
 
 The uses and origin of this acid will be noticed when we 
 reat of the animal fats generally. 
 
 Doeglingic (20.) Doeglingic acid is of no special interest ; it was found 
 by Scharling, in the oil of the Doegling (the Balcena rostrata 
 of the older zoologists, but now regarded as a species of Hy- 
 peroodon). 
 
 THE BENZOIC-ACID GEOFF. 
 
 C n H n . 9 3 .HO. 
 
 (21.) We should not refer to this group of acids, if it were 
 not that its representative, benzoic acid, sometimes occurs in 
 the animal fluids, and that the change which it undergoes in 
 the animal body elucidates certain points connected witB the 
 metamorphosis of tissue. 
 
 Benzoic Benzoic acid is represented by the formula C 14 H 5 3 .HO; 
 
 or, if it be regarded as a conjugated oxalic acid, by (C 12 H 5 ) 
 C 2 3 .HO. It is solid at ordinary temperatures, but fuses 
 at about 250, and boils and sublimes without decomposition 
 at 462. When obtained in this way, it occurs in delicate 
 needles; when precipitated from a spirituous solution, it 
 usually crystallises in scales. It is slightly soluble in cold 
 water, dissolves freely in hot water, is soluble in alcohol and 
 (to a less extent) in ether, and its solutions redden litmus. 
 
 The only acid occurring in the animal body with which it 
 is likely to be confounded is hippuric acid. The mode of dis- 
 tinguishing these acids is given in 52. 
 
 It is only in the urine that the presence of benzoic acid has 
 ever been suspected ; and here it merely occurs as a product 
 of the decomposition of hippuric acid, which, as will be pre- 
 sently shown, may be regarded as a conjugated benzoic acid. 
 
LACTIC ACID. 19 
 
 (See 52.) It is never found in the fresh urine even of the 
 herbivora, although Liebig at one time held the opposite 
 opinion. After the use of benzoic acid we always find a large 
 quantity of hippuric acid in the urine * ; it reappears, how- 
 ever, unchanged in the sweat. 
 
 (22.) Salicylic acid is an analogous acid, differing only from Salicylic 
 benzoic acid in containing two more atoms of oxygen. It 
 occurs in the urine, in association with salicylous acid, after 
 the use of salicin ; as these acids occur in castoreum, in con- 
 sequence of the willow-bark being a favourite article of food 
 with the beaver, they may be regarded as normal constituents 
 of the urine of that animal. 
 
 THE LACTIC -ACID GTROUP. 
 
 
 (23.) The three following acids belong to this group : 
 Glycicacid .... C 4 H 3 5 .HO. 
 Lactic acid . . . . C 6 H 5 5 . HO. 
 and Leucic acid .... C 12 H n 5 .ILO. 
 
 As neither glycic nor leucic acid has been as yet detected 
 preformed in the animal organism, we shall confine our re- 
 marks to Lactic acid. 
 
 The researches of Strecker seem to have established the Lactic 
 fact that lactic acid should be regarded as formic acid conju- 
 gated with aldehyde f as an adjunct; its rational formula 
 therefore is C 4 H 4 2 .C 2 H0 3 .HO. 
 
 * Duchek has made some important observations regarding the proportions 
 in which hippuric acid occurs in the urine after the ingestion of benzoic acid. 
 When 1 gramme of benzoic acid was taken, 0-714 of a gramme of hippuric 
 acid was excreted ; 2 grammes were followed by the excretion of 1-857 
 grammes of hippuric acid and 0'421 of a gramme of benzoic acid ; and 4 
 grammes, by T714 of hippuric acid and 2*500 of benzoic acid. Hence the 
 limit at which the conversion ceases is soon reached. 
 
 f The formula for aldehyde is C 4 IIjO . HO. It is a clear colourless liquid 
 
 C 2 
 
20 PHYSIOLOGICAL CHEMISTRY. 
 
 Lactic acid, when deprived as much as possible of water, is 
 an oily fluid which does not solidify at the greatest cold, with 
 a strongly acid taste, no odour, and soluble in water, alcohol, 
 and ether, in all proportions ; it has a very acid reaction, de- 
 composes when heated, and displaces not only the volatile 
 acids, but some of the stronger mineral acids from their 
 salts. 
 
 The determination of the presence of lactic acid is one of 
 the most difficult tasks in analytical chemistry, and we have 
 generally to found our decision regarding its occurrence on 
 the crystalline form of its salts. The most characteristic forms 
 are those of the lactates of lime, copper, and zinc. The best 
 method of detecting small quantities of lactic acid in animal 
 matters is that of Scherer, of which I have given an abstract 
 in the appendix to the third volume of Lehmann's " Phy- 
 siological Chemistry." 
 
 Its occur- Lactic acid, both in its free and combined state, occurs very 
 frequently, but by no means invariably, in the gastric juice, in 
 association with hydrochloric acid, which is usually present in 
 that fluid. In the saliva it has only been detected with cer- 
 tainty in cases of diabetes. The acid reaction which the 
 contents of the duodenum and jejunum present, especially 
 after the use of vegetable food, mainly depends on lactic acid, 
 and crystals of lactate of lime (Plate Lfig. 6.) have been re- 
 peatedly obtained by Lehmann from an alcoholic solution of 
 the contents of the duodenum of the horse. The strong acid 
 reaction presented by the contents of the large intestine after 
 the ingestion of amylaceous and saccharine food, is due to the 
 production, by fermentation, of this acid, which is then accom- 
 panied by butyric acid. 
 
 It has not yet been ascertained whether lactates are con- 
 stantly present in the chyle. Lehmann detected them in the 
 chyle obtained from the thoracic duct in two horses, one of 
 
 of a peculiar ethereal odour. It is called aldehyde, because it may be regarded 
 as alcohol deprived of part of its hydrogen, a?-cohol <&%?- rogenatum. 
 
LACTIC ACID. 21 
 
 which had been fed two hours before its death with oats, and 
 the other with starch-balls. Hence it may be regarded as an 
 established fact that, even if not always present, they certainly 
 occur in this fluid during the digestion of amylaceous food. 
 
 No one has definitely established the presence of lactates in 
 the lymph ; but as we cannot conceive that the lactic acid, 
 which is so abundantly formed in the muscles, can be carried 
 off by any other channel than by the lymphatics, and as, 
 further, lymph, whose reaction was scarcely or not at all alka- 
 line, and whose albuminous constituents were removed previous 
 to incineration, has been then found to yield much car- 
 bonated alkali, they most probably exist in this fluid. 
 
 The recognition of lactates in the healthy blood, into which 
 they must be transmitted from the intestinal canal and the 
 muscular tissue, is impossible in consequence of their very- 
 rapid oxidation and perfect combustion. The rapidity with 
 which lactates in the blood are converted into carbonates is 
 proved by experiments made by Lehmann and others, of in- 
 jecting lactate of soda into the jugular veins of dogs ; after 
 five, or at latest after twelve minutes, the urine exhibited an 
 alkaline reaction, which showed that the lactate had been 
 oxidised and converted into a carbonate. Lactic acid may, 
 however, collect abnormally in the blood, in cases in which 
 the normal oxidation of that fluid is impeded, in such quan- 
 tities as to be detected chemically. Blood, with an acid 
 reaction due to the presence of this acid, has been observed 
 by Scherer and Lehmann in puerperal fever, pyaemia, and 
 leucaemia. 
 
 Lactic acid has been found, both in a free and in a combined 
 state, in purulent exudations, especially in cases of puerperal 
 fever. 
 
 Although this acid was originally obtained by Scheele from 
 milk, it does not occur in the normal human milk, which 
 generally has an alkaline reaction. It is only in an abnormal 
 state, or after a purely animal diet, that milk with an acid 
 
 c 3 
 
22 PHYSIOLOGICAL CHEMISTRY. 
 
 reaction, due probably to lactic acid, is secreted. Healthy 
 milk, however, soon acquires an acid reaction, which is de- 
 pendent on the formation of lactic acid from its sugar by 
 fermentation. Schlossberger has shown that in the carnivora 
 this fluid is usually acid, the reaction being doubtless due to 
 lactic acid. 
 
 Free lactic acid exists in such abundant quantity in the 
 muscles of carnivorous as well as of herbivorous animals, that 
 Liebig believes that it is more than sufficient to saturate the 
 alkali of the alkaline fluids of the animal body. It likewise 
 occurs in the juice of the smooth muscles and of the spleen. 
 
 Grorup-Besanez found it in small quantity in the thymus 
 gland of the calf, and in the spleen, liver, pancreas,- kidneys, 
 lungs, and thyroid gland of the ox ; and von Bibra has found 
 it in the brain. 
 
 The recent investigations of Schottin, made under the 
 immediate superintendence of Lehmann, disprove the existence 
 of this acid in normal and even in morbid sweat, although 
 several of the older chemists, and recently Favre, maintain 
 that it occurs in that fluid. 
 
 Lactic acid is sometimes, but not always, found in the 
 urine. " In all cases," says Lehmann, " where the supply of 
 lactates to the blood is very great whether this depends on 
 an excess of acid being formed in the muscles, or on the use 
 of a diet tending to produce it, or on an imperfect process of 
 oxidation in the blood lactic acid may be detected in the 
 urine with all the certainty which in the present state of 
 chemistry can be expected. Hence it is that in the urine of 
 the same individual lactic acid may on one day be present 
 and on another absent ; why in many persons no lactic acid 
 can be detected in the urine, and in others again (in whom 
 the respiratory process is imperfectly accomplished) it is con- 
 stantly present in the urine ; why stall-fed animals, living 
 on amylaceous fodder, excrete lactic acid by the kidneys (and 
 in part also by the mammary glands), whilst under other con- 
 
LACTIC ACID. 23 
 
 ditions this acid cannot be discovered in their urine ; and 
 why, finally, in most febrile diseases lactic acid may be recog- 
 nised in the urine.*' Thus lactic acid occurs in the urine 
 under the same conditions which give rise to the development 
 of oxalic acid (see 3) ; and hence the detection of oxalate 
 of lime by the microscope leads us to the inference that lactic 
 acid is probably also present. It has been found in con- 
 siderable excess in the urine in cases of rachitis and osteo- 
 malacia. In examining this secretion for lactic acid, we must 
 not overlook the fact that it is formed by a process of fer- 
 mentation, probably from that unknown matter to which we 
 apply the term extractive, when urine is exposed to the action 
 of the atmosphere. 
 
 Lassaigne believes that he has found lactate of soda in the 
 allantoic fluid of a calf. 
 
 Schmidt has separated lactic acid from the strongly acid 
 fluid yielded by the softened cylindrical bones in a case of 
 osteo-malacia. 
 
 The lactic acid, which is thus widely diffused throughout Its origin, 
 the animal fluids, may be referred to a treble origin. No one 
 can doubt that the acid found in the contents of the intestines, 
 and in the chyle after the digestion of vegetables, owes its 
 formation to the amylaceous or saccharine matters contained 
 in the food undergoing a change similar to that which takes 
 place in the fermentation of milk ; moreover, the sugar which 
 is formed in the liver, both in carnivorous and herbivorous 
 animals, is similarly converted in the blood into lactic acid ; 
 while the acid which is found in such large quantity in the 
 muscles cannot be referred to these sources, but must be 
 considered as a product of the metamorphosis of the muscular 
 fibre a view confirmed by the fact that the amount of free 
 acid is proportional to the extent to which the muscles had 
 been previously exercised. 
 
 The physiological value of lactic acid is by no means incon- its uses, 
 siderable; for, in the first place, in association with free 
 
 c 4 
 
24 PHYSIOLOGICAL CHEMISTRY. 
 
 hydrochloric acid, it essentially contributes to the digestive 
 power of the gastric juice, no other mineral or organic acid 
 possessing the property of being able to replace these; se- 
 condly, the free lactic acid in the intestinal canal assists 
 materially in promoting an absorption or transudation of the 
 digested food into the alkaline blood or lymph, in accordance 
 with the known laws of endosmosis*; thirdly, the alkaline 
 lactates are excellent supporters of animal heat, in conse- 
 quence of the rapid combustion which they undergo in the 
 blood ; and, lastly, it is probable (as Liebig supposes) that an 
 electric tension, influencing the function of the muscles, is 
 established by the acid muscular juice and the alkaline con- 
 tents of the capillaries. 
 
 NON-NITROGENOUS RESINOUS ACIDS. 
 
 (24.) There are two acids f belonging to this group which 
 require to be noticed in this place, namely 
 
 Lithofellic acid . . . C 40 H 36 7 . HO, 
 and Cholic acid * ... C 48 H 39 9 .HO. 
 
 Lithofellic Lithofellic acid is a crystalline resinous acid which exists 
 only in certain bezoars which are obtained from the intestines 
 of various species of goats inhabiting the East. Whether it is 
 derived from the food of those animals, or whether it takes 
 its origin in the bile, is as yet undecided. 
 
 Cholic acid. (25.) Cholic acid\ occurs in colourless glistening crystals, 
 
 * See especially Graham's Bakerian Lecture on Osmotic Force, in the 
 " Philosophical Transactions," for 1854, p. 227. 
 
 f To these we ought, perhaps, to add benzoglycic acid, C J8 H 7 7 .HO, 
 although it has never yet been found preformed in the animal organism. It 
 receives its name because it may be regarded as a conjugated compound, com- 
 posed of benzoic and glycic acids, C, 4 H 5 O 3 . C 4 H 3 5 , being readily decom- 
 posed into these two acids when warmed with a dilute acid. It is of interest, 
 as indicating the probable theoretical composition of hippuric acid. (See 51.) 
 
 J This is Demarcay's cholic acid; it is the cholalic acid of Strecker. The 
 names of the biliary acids are very confusing, the same term being frequently 
 applied by different chemists to very different substances. 
 
C1IOLIC ACID. 25 
 
 which effloresce on exposure to the air, and have a peculiarly 
 bitter taste. It is only slightly soluble in water, but dissolves 
 very readily in . alcohol, especially when heated, from which 
 it crystallises in tetrahedra ; it dissolves rather less freely in 
 ether, from which it separates in rhombic tablets. (Plate /. 
 fig. 7.) This acid strongly reddens litmus, fuses at 383: at a 
 slightly higher temperature it loses its atom of basic water, 
 and is converted into choloidic acid, and at 554 into dyslysin. 
 If boiled for some time in hydrochloric acid, it ceases to be 
 crystallisable and is converted into choloidic acid, and on 
 further boiling, it loses its acid properties and forms dyslysin. 
 By the action of boiling nitric acid, it is for the most part 
 converted into capric, caprylic, and cholesteric acids. It dis- 
 solves in sulphuric acid, and, if we add a drop of syrup to the 
 solution, it assumes a beautiful purple tint. This, which is 
 known as Pettenkofer's test, is equally applicable whether the Pettcn- 
 cholic acid be free, or combined with the adjuncts with which 
 it is naturally conjugated in the bile, or metamorphosed into 
 choloidic acid : hence we can apply it to discover generally 
 either the presence of this essential biliary acid, or of one of its 
 derivatives. The following is the best method of proceeding 
 in testing for biliary matter in a fluid which is suspected to 
 contain it. The alcoholic extract of the fluid must be dis- 
 solved in a little water, with which we must then mix a drop 
 of syrup (consisting of 1 part of sugar to 4 of water), and 
 strong sulphuric acid must be added by drops to the mixture. 
 The fluid first becomes turbid, from the separation of the 
 cholic acid, which, however, dissolves on the addition of a 
 little more sulphuric acid : for a few moments its colour is 
 yellowish ; it soon, however, becomes of a pale cherry colour, 
 then of a deep carmine, of a purple, and, finally, of an intense 
 violet tint. We must not allow the temperature to be raised 
 by the sulphuric acid beyond about 120, which seems to be 
 the most favourable heat for the development of the reaction. 
 Should the fluid at first assume only a cherry-red or a deep 
 
26 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Choloidic 
 acid. 
 
 Dyslysin. 
 
 Occurrence 
 of cholic 
 acid. 
 
 carmine tint, it must be allowed to stand for some time. Any 
 kind of sugar may be employed, or acetic acid may be used in 
 its place. 
 
 It has been recently discovered that oleic acid and certain 
 ethereal oils possess a similar power of developing a violet 
 tint with concentrated sulphuric acid and sugar ; as, however, 
 the reaction takes place very slowly in these fluids, and merely 
 on the surface (it being due to the absorption of oxygen), the 
 value of the test is not affected. 
 
 As choloidic acid and dyslysin are sometimes found in the 
 animal body in association with cholic acid, it is expedient 
 briefly to notice their composition and leading characters. 
 
 (26.) Choloidic acid, as it exists in its salts, is perfectly 
 isomeric with cholic acid. We have already mentioned its 
 formation from cholic acid by the aid of heat and of hydro- 
 chloric acid ; it seems likewise to be occasionally produced, in 
 association with dyslysin, from the decomposition of the bile 
 in the lower part of the small intestine (see 175). In a 
 state of purity it is a white, amorphous, resinous, pulverisable 
 mass, which is insoluble in water, but dissolves readily in 
 alcohol ; it is almost insoluble in ether, which thus serves to 
 distinguish it from cholic acid. 
 
 (27.) Dyslysin seems to be formed from choloidic acid by 
 the abstraction of 3 atoms of water, its composition being 
 represented by the formula C 48 H 36 6 . Its mode of production 
 has been already mentioned. It forms a grayish white mass, 
 which is soluble in ether, but insoluble in water, cold alcohol, 
 acids, and alkalies ; hence its name. When boiled with an 
 alcoholic solution of potash it is reconverted into choloidic 
 acid. 
 
 (28.) In the normal bile cholic acid is always found in 
 conjugation with taurine or glycine (see 53 and 55), and 
 in this state of combination it sometimes passes, in abnormal 
 conditions of the system, into the blood and other fluids. In 
 the intestinal canal, on the other hand, it is very soon 
 separated from its nitrogenous adjuncts, and is partly con- 
 
CHOLIC ACID. 27 
 
 verted into choloidic acid and dyslysin. It is found in very 
 small quantity in the normal excrements, but to a con- 
 siderably larger amount in cases of diarrhoea. 
 
 Cholic acid is unquestionably formed in the liver, but we Its forma- 
 do not definitely know from what materials it is produced in 
 that organ. Lehmann inclines to the view that, since fats 
 .contribute essentially to the formation of bile (as is shown 
 both by accurate comparative analyses of the blood entering 
 and leaving the liver, and by careful statistical observations 
 on living animals), it is very probable that this acid consists 
 of a combination of oleic acid and a carbo-hydrate C 12 H 6 6 ; 
 and this view is further supported by the fact that we know 
 that one carbo-hydrate, sugar, is formed in considerable quan- 
 tity in the liver. Moreover, a comparison of the respective 
 products of oxidation of cholic and oleic acids strengthens the 
 hypothesis ; for, when treated with concentrated nitric acid, 
 cholic acid yields precisely the same products of decomposi- 
 tion as oleic acid, and additionally a carbo-hydrate, namely, 
 cholesteric acid, whose composition is represented by the 
 formula C 8 H 4 4 . 
 
 (29.) TABULAR VIEW OF THE COMPOSITION OF THE NON-NITRO- 
 GENOUS ACIDS. 
 
 Oxalic acid, C 2 3 . HO. Formic acid, C 2 H0 3 . HO. 
 
 Carbon . * 26-667 Carbon * ' . 26-087 
 
 Oxygen . . 53-337 Hydrogen . . 2-174 
 
 Water. . . 20-000 Oxygen . . 52-174 
 
 Water . . . 19-565 
 
 Acetic acid, C 4 H 3 3 . HO. Metacetonic acid, C 6 H 5 3 . HO. 
 Carbon . . 40-000 Carbon . . 48-649 
 
 Hydrogen . . 5-000 Hydrogen . . 6-757 
 
 Oxygen . . 40-000 Oxygen . . 32-432 
 
 Water . 15-000 Water . . 12-162 
 
28 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Butyric acid, C 8 H 7 3 . HO. 
 
 Carbon . . 54-545 
 
 Hydrogen . . 7*955 
 
 Oxygen . . 27-273 
 
 Water . . . 10-227 
 
 Caproic acid, C 12 H H 3 . HO. 
 
 Carbon . . 62-069 
 
 Hydrogen . . 9-483 
 
 Oxygen . . 20-689 
 
 Water . 7-759 
 
 Valerianic acid, C 10 H 9 3 . HC 
 
 Carbon . . 58-824 
 
 Hydrogen . . 8-823 
 
 Oxygen . . 23-530 
 
 Water . . . 8-823 
 
 Caprylic acid, C 16 H 15 3 . HO 
 
 Carbon . ;'' 66-667 
 
 Hydrogen . . 10-416 
 
 Oxygen V V 16-667 
 
 Water 6-250 
 
 Capric acid, C 20 H 19 3 . HO. 
 
 Code acid, C 2( 
 
 ; H 25 3 -HO. 
 
 Carbon , 
 
 . 69-767 
 
 Carbon ', 
 
 . 72-90 
 
 Hydrogen . 
 Oxygen 
 Water . . 
 
 ;V 11-046 
 . 13-954 
 . 5-233 
 
 Hydrogen . 
 Oxygen * 
 Water . 
 
 . 11-68 
 . 11-22 
 . 4-20 
 
 Myristic acid, G 21 
 
 ,H 27 3 .HO. 
 
 Palmitic acid, C 
 
 32 H 31 3 .HO. 
 
 Carbon V 
 
 . 73-68 
 
 Carbon v 
 
 . 75-00 
 
 Hydrogen . 
 Oxygen 
 Water . v 
 
 , 11-85 
 . 10-53 
 . 3-94 
 
 Hydrogen . 
 Oxygen 
 Water . . 
 
 . 12-12 
 . 9-37 
 . 3-51 
 
 Margaric acid, C 
 
 34 H 33 3 .HO. 
 
 Stearic acid, C 36 H 35 3 . HO. 
 
 Carbon 
 
 . 75-556 
 
 Carbon 
 
 . 76-057 
 
 Hydrogen . 
 Oxygen 
 Water . . 
 
 . 12-222 
 . 8-889 
 . 3-333 
 
 Hydrogen . 
 Oxygen 
 Water. . 
 
 . 12-324 
 . 8-450 
 . 3-169 
 
 Sucduic acid, C 4 H 2 3 . HO. 
 
 Carbon . . 40-678 
 
 Hydrogen . . 3-390 
 
 Oxygen . . 40-678 
 
 Water . 15-254 
 
 Sebacic acid, C 10 H 8 3 . HO. 
 
 Carbon . . 59-406 
 
 Hydrogen . . 7-921 
 
 Oxygen . . 23-762 
 
 Water. 8-911 
 
TABULAR VIEW. 
 
 29 
 
 Oleic add, C 36 H 33 3 . HO. 
 
 Carbon . . ' 76-596 
 
 Hydrogen . . 11-702 
 
 Oxygen . . 8*511 
 
 Water . . . 3-191 
 
 Lactic acid, C 6 H 5 5 . HO. 
 
 Carbon . . 40-000 
 
 Hydrogen . . 5 '5 5 5 
 
 Oxygen . . 44*445 
 
 Water . 10-000 
 
 Benzoic acid, C 14 H 5 3 . HO. 
 
 Carbon . . 68-853 
 
 Hydrogen . . 4-098 
 
 Oxygen . . 19-672 
 
 Water . . . 7-377 
 
 Cholic acid, C 48 H 39 9 . HO. 
 
 Carbon . . 70-588 
 
 Hydrogen . . 9*559 
 
 Oxygen . . 17-647 
 
 Water . 2*206 
 
30 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 CHAPTER II. 
 
 NITROGENOUS BASIC BODIES. 
 
 (30.) THE organic bases are divisible into two well-marked 
 groups, according as they contain or are devoid of oxygen ; the 
 former being, without exception, volatile ; and the latter non- 
 volatile or fixed. 
 
 None of the volatile alkaloids have as yet been found 
 preformed in the animal body. Trimethylamine, 6 H 9 N, has 
 been found amongst the products of the spontaneous decom- 
 position of animal matters in herring-brine, putrid urine, and 
 alcohol in which anatomical preparations have been long pre- 
 served ; and some others are obtained artificially by the dry 
 distillation of bones, gelatin, &c. 
 
 (31.) The non-volatile alkaloids may be arranged in two 
 groups. 
 
 The first group includes four crystallisable homologous 
 bases, represented by the formula C n H n+1 N0 4 ; namely, 
 
 Glycine . ... . ; . C 4 H 5 N0 4 . 
 Sarcosine. . . . - .. ,. C 6 H 7 N0 4 . 
 A substance homologous to leucine 
 
 (not yet named) 
 
 C 10 H U N0 4 . 
 
 and Leucine . . . . . C 12 H 13 N0 4 . 
 
 These become broken up by nitrous acid, N0 3 , into acids 
 of the lactic-acid group: thus, for instance, glycine yields 
 glycic acid, in accordance with the following equation: 
 C 4 H 6 N0 4 + N0 3 = 2N + 2HO + C 4 H 3 5 . Under the action 
 of strong alkalies they lose two atoms of carbon and yield 
 one of the volatile fatty acids, glycine yielding formic acid ; 
 sarcosine, acetic acid ; and leucine, valerianic acid. The re- 
 
GLYCINE. LEUCINE. 31 
 
 action in the last case is expressed by the equation, C 1 . 7 H 13 N0 4 
 4- 3KO . HO = 2KO . C0 2 + H 3 N + 4H + KO . C 10 H 9 3 . 
 
 (32.) Glycine, known formerly as sugar of gelatin, and Glycine. 
 more recently as glycocoll, crystallises in colourless rhombic 
 prisms (Plate Lfig. 8.), which have a sweetish taste, and are 
 devoid of odour. It is very soluble in water, the solution 
 having no effect on vegetable colours, but does not dissolve 
 readily in alcohol. 
 
 It has been long known that glycine is a product of the 
 decomposition of animal substances, especially of gelatin, 
 when acted upon by strong acids or alkalies. Its occurrence, 
 however, in certain animal acids as a nitrogenous adjunct, is 
 a point of much more physiological importance ; thus, for in- 
 stance, conjugated with cholic acid, it occurs as glycocholic 
 acid in the bile ; and since hippuric acid, when heated with 
 strong mineral acids, yields glycine, it is regarded by some 
 chemists as glycobenzoic acid. 
 
 After the use of glycine the quantities of urea and uric 
 acid are increased, but no glycine passes unchanged into the 
 urine (Horsford). 
 
 (33.) Sarcosine has never been found preformed in the Sarcosine. 
 animal body, and is only known as a product of the decom- 
 position of creatine when acted upon by caustic baryta. 
 
 (34.) Leucine in a state of purity occurs in glistening Leucine. 
 colourless plates, which, when seen under the microscope, 
 appear as rhombic tablets and prisms, or as needles arranged in 
 star-like groups. Such is the description of the crystalline 
 form of leucine given by Lehmann and Funke. Virchow, who 
 has attentively studied this substance, (especially in relation to 
 its occurrence in the pancreas,) has, however, never been able 
 to perceive these plates, and in his examinations of leucine 
 (both natural and artificially prepared), even with the highest 
 powers, has only found acicular crystals. If, says Scherer*, we 
 
 * In his Eeport on the Progress of Pathological Chemistry during the year 
 1855, in Canstatt's Jahresbericht, where this subject is very fully discussed. ' 
 
32 PHYSIOLOGICAL CHEMISTRY. 
 
 allow leucine to crystallise from a solvent, we always first ob- 
 serve minute granules of a roundish form, which may be dis- 
 tinguished from fat-globules by their inferior brilliancy and 
 their paler edges. These often combine and form either 
 nodular or star-like masses. Different forms of the crystals, 
 as depicted both by Funke and Eobin, are given in PL II. 
 
 fig. i. 
 
 Leucine is* freely soluble in water, less so in alcohol, and is 
 insoluble in ether. Its solutions exert no influence on vegetable 
 colours. On saturating moderately concentrated nitric acid 
 with leucine, we obtain crystals of nitrate of leucine, or leuco- 
 nitric acid, the salts of which decrepitate when heated. Its 
 behaviour towards nitric acid, and its decomposition into va- 
 lerianic acid* (see 31), together with the observation of its 
 crystalline form, constitute tolerably certain means of distin- 
 guishing this substance. In most of the cases in which it is 
 reported to have been found in the animal tissues, its pre- 
 sence has however been established by ultimate analysis. 
 
 Leucine is obtained from numerous animal substances, in 
 various ways. It is produced by the action of strong acids or 
 alkalies on any of *the protein-bodies, and likewise during 
 their putrefaction ; it has also been similarly obtained from 
 elastic tissue, horn, feathers, hedge-hog spines, hair, and the 
 elytra of the cockchafer. 
 
 Its occur- Previous to the year 1853, the only fact tending to show 
 that leucine was probably an occasional constituent of the 
 animal body, was an isolated observation made by Liebig, 
 who, in his "Letters on Chemistry," mentions that he has found 
 it in the decoction of the liver of the calf. Since that period 
 the researches of Frerichs and Stadeler, of Kobin, of Virchow, 
 Scherer, Grorup-Besanez, and Cloetta, have shown that leucine 
 and the closely allied substance, tyrosine, have a much wider 
 distribution than was previously suspected. It exists in the 
 
 * Leucine also is readily converted into valerianic acid, if it be exposed to 
 the influence of a little muscular fibre or albumen in a state of putrefaction. 
 
LEUCINE. 33 
 
 blood, in the vascular glands, viz., the thymus gland, the thy- 
 roid body, and the spleen, in the liver and the bile, in the 
 pancreas and salivary glands and their secretions, in the con- 
 tents of the small intestine (derived probably from the 
 pancreatic fluid), in the lymphatic glands, in the lungs, and in 
 the kidneys ; and has been found in a diseased brain. That it 
 actually exists as leucine in the body, and is not a product of 
 decomposition, formed after death, is evident from the cir- 
 cumstances that it has been occasionally found in the urine (in 
 disease), and that it may be obtained from the pancreatic and 
 salivary secretions of living animals. 
 
 Leucine has been sought for unsuccessfully in the muscles. 
 
 It is in the pancreas that it occurs most abundantly. 
 
 The lienine discovered some years ago by Scherer in the 
 spleen, and the thymine, subsequently discovered by Grorup- 
 Besanez in the thymus gland, are now regarded by those 
 chemists as identical with leucine. 
 
 According to Bodeker, leucine is an ordinary constituent 
 of pus ; and it was especially abundant in the pus in a case of 
 necrosis of the upper jaw, arising from the fumes of phos- 
 phorus. 
 
 (35.) A body homologous to leucine , and very similar to it, 
 has been discovered by G-orup-Besanez in the pancreas of the 
 ox. Its formula is C 10 H n N0 4 . He gives a table in which the 
 properties of these two bodies are compared and contrasted, 
 in the Ann. d. Ch. u. Pharm. 1856, vol. xcviii. p. 20. 
 
 (36.) Tyrosine, whose composition is represented by the Tyrosine. 
 formula C 18 H n N0 6 , and which therefore does 'not strictly 
 belong to this group, is in many respects so closely allied 
 to leucine, that we shall notice it in this place. 
 
 It forms white silky crystals, which are very difficult of 
 solution in cold water, but dissolve more readily in hot water, 
 and are altogether insoluble in alcohol and ether. It dis- 
 solves readily in alkalies and acids, from which it again 
 crystallises unchanged on evaporation. I am not acquainted 
 
34 PHYSIOLOGICAL CHEMISTRY. 
 
 with any delineation of the crystalline forms which tyrosine 
 assumes ; the acicular crystals, which in single or double tufts, 
 or as spheres, are regarded by Robin and Yerdeil as leucine, 
 are supposed by Frerichs and Stadeler to be tyrosine. 
 
 Piria has discovered a very delicate test for tyrosine, which 
 is especially useful in distinguishing it from leucine, with 
 which it is usually associated. 
 
 If we place a little tyrosine (1-1 2th or 1-1 5th of a grain is suf- 
 ficient) on a watch-glass, moisten it with one or two drops of 
 sulphuric acid, allow it to stand for half an hour, then dilute 
 the mixture with water, saturate it when heated with carbonate 
 of lime, and after filtering add a few drops of a solution of 
 perchloride of iron, in which there is no free acid, we at once 
 obtain a very rich violet colour. This is known as Piria's test. 
 
 Tyrosine is formed, along with leucine and other compounds 
 not yet investigated, when albuminous or horny bodies are 
 decomposed either by acids, alkalies, or putrefaction. 
 
 Tyrosine is scarcely ever found in the animal body except 
 in association with leucine, and it almost always occurs in 
 much smaller quantity than the latter. It has been found 
 in the liver (in carcinomatous and atrophied states, but not in 
 health) by Frerichs and Stadeler, who regard it as a normal con- 
 stituent of the pancreas and pancreatic juice of men and 
 animals (the horse and ox), and who detected it in the urine 
 of a woman with acute atrophy of the liver. They searched in 
 vain for it in the spleen, salivary glands and saliva, lym- 
 phatic glands, thymus gland, thyroid body, brain, muscles, and 
 lungs ; and Grorup-Besanez was even less successful, failing to 
 find any trace of it in the thymus, thyroid body, liver, kidneys, 
 lungs, or spleen of the ox, and only once finding it in the 
 pancreas. Scherer has found leucine, and often tyrosine, in 
 all the human livers that he has examined, and confirms the 
 view that it is an ordinary constituent of the pancreas. 
 
 The modes in which leucine and tyrosine are artificially 
 prepared, indicate that they represent stages of the retrograde 
 
CREATINE. 35 
 
 metamorphoses of the albuminous tissues, acted upon pro- 
 bably by an animal ferment. In the case of the salivary 
 glands and pancreas, the ferments which exist in their normal 
 secretions are most likely the active agents. 
 
 (37.) The second group presents fewer points in common 
 than the first. They are for the most part crystallisable sub- 
 stances, occurring normally as preformed constituents of the 
 animal fluids, and are to be regarded as products of the 
 metamorphosis of the nitrogenous tissues. In this group we 
 place : 
 
 Creatine C 8 H 9 N 3 4 
 
 Creatinine C 8 H 7 N 3 2 
 
 Urea C 2 H 4 N 2 O 2 
 
 Allantoine C 8 H 6 N 4 6 
 
 (or, more correctly, C 8 H 5 N 4 5 . HO) 
 
 Hypoxanthine .... C 10 H 4 N 4 2 
 
 Xanthine C 10 H 4 N 4 4 
 
 Gruanine . . ; ' f> ' . . C 10 H 5 N 5 2 
 
 Myeline ? 
 
 Cystine C 6 H 6 NS 2 4 
 
 Taurine C 4 H 7 NS 2 6 
 
 Xanthine alone is not crystallisable, and xanthine and cystine 
 are the only two substances whose formation is due to ab- 
 normal processes. 
 
 None of these bodies, with the exception of creatinine, 
 possess decided basic properties; but we have deemed it 
 expedient, as a matter of convenience, to throw them together 
 in consequence of the similarity in their empirical composition 
 and in their physiological relations. 
 
 (38.) Creatine forms transparent, glistening crystals, whose Creatine. 
 leading forms are shown in Plate II. Jig. 2. It dissolves in 
 74-4 parts of cold water, and in boiling water in such quantity 
 that the solution on cooling solidifies into a mass of delicate 
 glistening needles. It is decomposed when boiled with baryta- 
 water into urea and sar cosine (C 8 H 9 N 3 4 . 2 HO = C 2 H 4 N 2 2 
 
 D 2 
 
36 PHYSIOLOGICAL CHEMISTKY. 
 
 + C 6 H 7 N0 4 ), but we are not justified in hence inferring that 
 these bodies are its proximate constituents. 
 
 There is no direct test for the detection of creatine ; and 
 the methods that have been employed to obtain it from flesh 
 and urine are too complicated to lead to trustworthy results 
 in the hands of any but experienced chemists. 
 
 Creatine is constantly present in the juice both of voluntary 
 and involuntary muscles. The quantity differs in the flesh 
 of different kinds of animals, and even in different muscles of 
 the same animal, but is always very small. Lean animals 
 yield, relatively, more creatine than fat ones. 
 
 According to Liebig, the flesh of hens yields the largest 
 amount of creatine, namely, 0-32-J, the average , quantity 
 yielded by horse or ox-flesh being 0'07-g-. Gregory obtained 
 from 0-1375 to 0*1418^- of this substance from the heart of 
 the ox, and from 0-0935 to 0-3-J from the flesh of the cod-fish. 
 Schlossberger found 0-06 7-g- in human flesh. 
 
 Verdeil and Marcet have found it in very minute quantity 
 in the blood of oxen. 
 
 It does not exist in the liver or kidneys, but has been 
 found by Lerch* amongst the soluble constituents of the 
 human brain. 
 
 It is doubtful whether it is a normal constituent of the 
 urine, although small quantities of it can usually be obtained 
 from that fluid ; there being reasons for believing that it is 
 formed from creatinine during the process of extraction. 
 
 Verdeil and Robin have found it in the liquor amnii of a 
 woman who died in the eighth month of pregnancy. Its 
 presence in that fluid had been previously suspected by 
 Scherer. 
 
 Although the view has been advocated that, from its occur- 
 ring in the muscular juice, and from its large amount of 
 nitrogen, creatine is an important nutritive agent, there are 
 
 * Schmidt's Jahrbiicher, 1856, vol. xcvi. p. 152, 
 
CREATININE. UREA. 37 
 
 most decisive reasons for ranking it amongst the products 
 of excretion ; for, in the first place, if it could be employed 
 with further advantage in the organism, it (or its near ally, 
 creatinine) would not be allowed to escape by the kidneys ; 
 and, secondly, the readiness with which it becomes decomposed 
 into unquestionable products of excretion, as creatinine, urea, 
 and sarcosine, proves that it approximates more nearly to these 
 substances than to albumen and fibrin. 
 
 (39.) Creatinine, the most decided alkaloid of this class of Creatinine. 
 bodies, forms colourless, glistening crystals of the form repre- 
 sented in Plate ILfig. 3. It has almost as caustic a taste as 
 ammonia, reacts strongly on vegetable colours, is soluble in 
 11 '5 parts of water at an ordinary temperature, and still more 
 readily in hot water, and dissolves tolerably freely in spirit 
 and in ether. It expels ammonia from ammoniacal salts, 
 forms beautiful blue crystalline double salts with salts of the 
 oxide of copper, and its watery solution, when treated with 
 chloride of zinc, at once yields a granular crystalline pre- 
 cipitate, the particles of which, when seen under the micro- 
 scope, are found to consist of very delicate concentrically- 
 grouped needles, 
 
 Creatinine occurs both in the muscular juice and in the its occur, 
 urine ; in the latter fluid it occurs in greater and in the former r 
 fluid in less quantity than creatine ; its amount is, however, 
 too small to be determined quantitatively. Traces of it have 
 also been found in the blood and in the liquor amnii. 
 
 There can be little doubt that creatinine takes its origin 
 from creatine, for, independently of the fact that this change 
 may be readily effected artificially, this is almost proved by 
 the above-mentioned circumstance that these two bodies occur 
 in an inverse ratio in the muscles and in the urine, and by 
 the observation made by Liebig that urine which has become 
 putrid yields no creatine, but only creatinine. 
 
 (40.) Urea crystallises, when it separates rapidly from a 
 concentrated solution, in white silky needles ; when crystallised 
 
38 PHYSIOLOGICAL CHEMISTRY. 
 
 more slowly from dilute solutions, it forms white, nearly 
 transparent, striated four-sided prisms, whose ends are bounded 
 by one or two oblique surfaces. (Plate II. Jig. 4.) It is devoid 
 of smell, of a saltish, cooling taste, dissolves readily in its own 
 weight of water at an ordinary temperature, and even more 
 freely in hot water ; it is also soluble in 4 or 5 parts of cold 
 and in 2 parts of warm alcohol ; but is insoluble in pure ether. 
 Its solutions exact no action on vegetable colours. 
 
 (41.) We shall confine our remarks upon the chemical 
 reactions and combinations of urea almost entirely to points 
 bearing upon its qualitative and quantitative detection. 
 
 On boiling urea with strong mineral acids or with caustic 
 alkalies, it takes up 2 atoms of water, and is decomposed 
 into carbonic acid and ammonia (C 2 H 4 N 2 2 + 2HO = 2H 3 N 
 4- 2C0 2 ). Ragsky and Heintz employ this reaction for the 
 determination of urea. The acid they use is sulphuric acid ; 
 the carbonic acid is given off and the ammonia separated 
 from the sulphuric acid by bichloride of platinum ; from the 
 weight of the resulting compound, the quantity of ammonia, 
 and therefore of decomposed urea, may be reckoned ; 1 part 
 corresponding to O'l 34498 of urea. The same reaction takes 
 place at an ordinary temperature when we mix putrefying 
 nitrogenous matters with a solution of urea (as is seen in the 
 ordinary alkaline fermentation of the urine excited by the 
 mucus of the bladder), or when we heat a solution of urea in 
 a closed tube or vessel to a temperature of from 250 to 460. 
 Bunsen employs this means of determining the amount of 
 urea in a solution. He mixes it with a solution of chloride 
 of barium, exposes the mixture to the required heat, and 
 afterwards calculates the quantity of urea from the amount of 
 carbonate of baryta that is formed ; 1 part of carbonate of 
 baryta corresponds to 0-4041 of urea. 
 
 By nitrous acid urea is decomposed into nitrogen, water, 
 and carbonic acid (C 2 H 4 N 2 2 + 2HO + 2N0 3 = 6HO + 2C0 2 
 + 4N). On this reaction Millon founds his mode of deter- 
 
UREA. 39 
 
 mination : a solution of nitrate of suboxide of mercury is dis- 
 solved in nitric acid, and added to a weighed solution of urea ; 
 on warming this mixture the nitrous acid reacting on the 
 urea causes the evolution of nitrogen and carbonic acid, which 
 latter gas is caught in a potash-apparatus and weighed. 
 
 If urea be mixed with a solution of the hypochlorite of 
 soda, potash, or lime, it is decomposed into nitrogen, carbonic 
 acid, and water. A measured quantity of the solution of 
 urea is introduced into a glass tube, partly filled with mer- 
 cury, an excess of the hypochlorite is added, and the tube is 
 inverted : in a few seconds the urea begins to decompose, the 
 carbonic acid is absorbed by the hypochlorite, and the nitrogen 
 collects in the upper part of the tube. In three or four hours 
 the decomposition is complete, and by a simple calculation 
 we can estimate the amount of urea from the quantity of 
 nitrogen. This method of determining the amount of urea 
 has been suggested by Dr. E. Davy. 
 
 On gradually adding to a dilute solution of urea a dilute Combina- 
 solution of nitrate of protoxide of mercury (the atomic O xide of 
 weight of mercury being 100), and neutralising the free acid mercut y* 
 of the mixture from time to time by a dilute solution of 
 carbonate of soda, a flocculent snow-white precipitate, which 
 consists of 1 atom of urea combined with 4 atoms of oxide of 
 mercury, and which is quite insoluble in water, is thrown 
 down. If the addition of the salt of mercury and of carbonate 
 of soda be continued alternately, as long as this precipitate is 
 formed, a point is reached at which the addition of a drop of 
 the alkaline solution occasions a yellow colour, from the 
 formation of the hydrated oxide or the basic nitrate of mer- 
 cury. This takes place as soon as all the urea is precipitated, 
 when the carbonate of soda at once acts on the mercurial 
 solution in the above-named manner. Hence, if the quantity 
 of mercury in the test-fluid be known, we can calculate the 
 amount of urea in the fluid by observing the quantity of 
 test-fluid required for the complete precipitation. It is on 
 
 D 4 
 
40 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 With ox- 
 alic acid. 
 
 Tests. 
 
 this reaction that Liebig bases his celebrated method of 
 determining the amount of urea volumetrically. 
 
 Chloride of mercury (corrosive sublimate) does not throw 
 down a precipitate from neutral or acid solutions of urea ; if, 
 however, bicarbonate of potash be added in excess, we get the 
 previously-described white precipitate. 
 
 Urea and chloride of sodium form a soluble compound, 
 which crystallises in glistening octohedra or rhombic prisms 
 'with oblique terminal surfaces. It contains one atom each 
 of urea and chloride of sodium with two atoms of water. It 
 is possible that urea may exist in this combination in the 
 animal body. 
 
 There are two acids with which urea forms important com- 
 pounds ; namely, nitric and oxalic acids. 
 
 If we mix a somewhat concentrated solution of urea with 
 pure and moderately strong nitric acid, the resulting com- 
 pound of nitrate of urea with one atom of water of crystallisa- 
 tion is soon observed to separate in white glistening scales or 
 laminae. When the amount of urea in solution is very great, 
 a semi-solid mass is at once formed on the addition of the 
 acid. 
 
 On examining under the microscope the contact of nitric 
 acid with a drop of a solution of urea, we first observe very 
 obtuse rhombic octohedra, which, by the accumulation of 
 particles, increase in size, and become converted into rhombic 
 or hexagonal tablets. (Plate II. Jig. 4.) These crystals occur 
 isolated, or in uniformly superimposed masses. 
 
 This salt dissolves in about 8 parts of pure water, but is 
 less soluble if the water contains a little nitric acid. It con- 
 tains 48'78-g- of urea. 
 
 On adding oxalic acid to a solution either of the preceding 
 salt or of urea, we obtain a more insoluble salt, the oxalate of 
 urea. 
 
 Its behaviour towards nitric and oxalic acids affords us the 
 best means of testing for this substance. In searching for it in 
 
UREA. 
 
 41 
 
 an albuminous fluid we should add a few drops of acetic acid, 
 boil, and filter, by which means we remove as far as possible 
 the coagulable matters. The residue of the filtrate should be 
 extracted with cold alcohol, and the solution evaporated, so 
 as to cause the chloride of sodium (taken up by the cold 
 alcohol) to separate as much as possible in crystals : on now 
 bringing a drop of the mother-liquid in contact with nitric 
 acid under the microscope, we shall observe the formation of 
 the crystals which have been already described ; and from the 
 solution of these crystals we can prepare and examine those 
 of the oxalate. 
 
 (42.) Urea is the most essential constituent of the urine, Occur- 
 amounting to from 77 to 82-J of the solid residue in man, and 
 to considerably more in healthy carnivora. In normal human 
 urine, which is extremely variable in relation to the amount 
 of its water, the quantity usually varies from 15 to 38 in 1000 
 parts, 25 being about the average. 
 
 The amount of urea excreted daily by an adult man of ordi- Daily 
 nary size, has been variously estimated by different chemists, as 
 may be seen by reference to the subjoined analyses (by Scherer, 
 Eummel, and Bischoff) of the urea at different ages, and in 
 both sexes. According to Lehmann, a healthy man excretes, 
 in 24 hours, from 22 to 54 grammes of urea, 32 grammes 
 being about the average quantity : a good deal depends upon 
 the weight, a man weighing 16 stones or more excreting 37 
 or 40 grammes, while a man of 9 or 10 stones does not ex- 
 crete more than from 28 to 32 grammes. 
 
 SCHERER. 
 
 amount. 
 
 
 0-) 
 
 (2.) 
 
 (3.) 
 
 (4.) 
 
 
 Girl. 
 
 Boy. 
 
 Man. 
 
 Man. 
 
 Age (in years) 
 
 31 
 
 7 
 
 22 
 
 38 
 
 Weight in English pounds .... 
 
 357 
 
 49-2 
 
 137-8 
 
 1537 
 
 Urea in 24 hours, in grammes 
 
 12-98 
 
 18-29 
 
 27-01 
 
 29-82 
 
 Daily urea for 1000 parts of bodily weight . 
 
 0-79 
 
 081 
 
 0-43 
 
 0-42 
 
42 
 
 PHYSIOLOGICAL CHEMISTRY. 
 RUMMEL. 
 
 
 (5.) 
 Boy. 
 
 (6.) 
 Boy. 
 
 at 
 
 (8.) 
 
 Youth. 
 
 (9.) 
 
 Man. 
 
 (10.) 
 
 Man. 
 
 Age (in years) 
 Weight in English pounds 
 
 3 
 
 29-8 
 
 4 
 31-7 
 
 5 
 
 36-9 
 
 18 
 129-1 
 
 31 
 163-7 
 
 65 
 127-9 
 
 Urea in 24 hours, in grammes 
 
 13-57 
 
 15-59 
 
 18-22 
 
 36-52 
 
 39-28 
 
 19-17 
 
 Daily urea for 1000 parts of 
 
 
 
 
 
 
 
 bodily weight 
 
 1-03 
 
 1-08 
 
 1-08 
 
 0-62 
 
 0-51 
 
 0-33 
 
 BISCHOFF. 
 
 
 (11.) 
 
 (12.) 
 
 (13.) 
 
 (14.) 
 
 (15.) 
 
 
 Boy. 
 
 Youth. 
 
 Girl. 
 
 Woman 
 
 Man.* 
 
 Age (in years) .... 
 Weight in English pounds 
 
 3 
 35 
 
 16 
 107 
 
 18 
 145 
 
 43 
 197 
 
 45 
 237 
 
 Urea in 24 hours, in grammes . 
 
 4-27 
 
 19-86 
 
 20-19 
 
 25-32 
 
 37-70 
 
 Daily urea for 1000 parts of bodily 
 
 
 
 
 
 
 weight 
 
 0-53 
 
 0-41 
 
 0'30 
 
 0-28 
 
 0-35 
 
 
 
 
 
 1 
 
 These analyses, on the whole, bear out Lehmann's statement 
 regarding the influence of weight on the amount of urea 
 (compare analyses (3), (4), and (9), ) ; but that the quantity 
 of urea does not always vary directly as the weight, is shown 
 by analysis (8). 
 
 We see from the above tables (excluding case 11, which 
 seems to be exceptional), that for a definite bodily weight 
 (say for instance 1000 parts) there is about three times as 
 much urea excreted in childhood (between the ages of 3 and 
 7), as at the age of 65, an intermediate quantity being yielded 
 in adult life. 
 
 The latest observations on the amount of urea excreted 
 normally, and under various conditions, are those of Beigel. 
 From 58 observations made on 10 healthy young men 
 between the ages of 20 and 30, and living their ordinary 
 
 * The " man " is Bischoff himself : in 40 analyses of his own urine the 
 maximum quantity of urea was 48'87 and the minimum 29-34 grammes. 
 
UREA. 43 
 
 mode of life in relation to diet and exercise, he deduces as the 
 average amount, 35*69 grammes; and he finds that for every 
 1000 parts of bodily weight they yield daily 0*46 of urea, 
 while from corresponding observations on 6 healthy young 
 women between the ages of 19 and 30 years, he infers that Influence 
 the normal daily quantity of urea excreted by them amounts 
 to 27*61 grammes, and that for 1000 parts of bodily weight 
 they yield 0-42 of urea. Hence, he observes, women excrete 
 daily 8 -03 grammes less urea than men; but he apparently 
 overlooks the fact that the weight of the men averaged 76*1 
 kilogrammes (or about 168lbs), while the mean weight of 
 the women was only 64*5 kilogrammes (or about 142 Ibs). 
 Making due allowance for the lighter average weight of 
 women, the smaller quantity of nitrogenous food which they 
 usually take, and the less severe bodily exercise they undergo 
 and, as we shall immediately see, all these are factors in 
 this question there seems no evidence that sex directly 
 influences the excretion of urea. 
 
 The influence which the nature of the food exerts on the Of food, 
 amount of urea, is forcibly shown by Lehmann's experiments 
 upon himself, BeigeFs upon healthy young men and women, 
 and Bischoffs on dogs. Lehmann found that on a purely 
 animal diet, or on food very rich in nitrogen, there were often 
 two-fifths more urea excreted than on a mixed diet ; while on 
 a mixed diet there was almost one-third more than on a 
 purely vegetable diet ; while, finally, on a non-nitrogenous diet 
 the amount of urea was less than half the quantity excreted 
 during a mixed diet. The following are his mean results : 
 On an ordinary mixed diet, 32*5 grammes; on a purely ani- 
 mal diet, 53-2 grammes ; on a purely vegetable diet, 22-5 
 grammes; and on non-nitrogenous diet, 15*4 grammes. Beigel 
 found that healthy men living on a very scanty diet (of rolls 
 and a kind of porridge), and taking no exercise whatever (lying 
 in bed except for three hours which were spent on the sofa), 
 excreted only 31 '8 6 grammes of urea, and that with strong 
 
44 PHYSIOLOGICAL CHEMISTRY. 
 
 exercise it rose to 33-32 grammes ; and that the same persons, 
 when enjoying a superabundant animal diet, and plenty of 
 bottled porter, excreted, when spending the day on the sofa, 
 46-10 grammes, and with strong exercise, 52-26 grammes. 
 Hence he draws the inference that a diminution in the amount 
 of nitrogenous food does not produce so marked an effect in 
 causing a decrease of the urea as a superfluity of such food 
 produces in augmenting the urea. 
 
 In two syphilitic patients (men aged 22 and 26 years), who 
 were undergoing the so-called hunger-cure, whose urine was 
 examined for 8 and 10 days respectively, the mean daily 
 quantities of urea were 17*83 and 22-715 grammes. 
 
 Bischoff believes that the increase of the urea is only limited 
 by the power of the individual to dissolve and digest nitro- 
 genous food : one of the dogs on which he experimented, when 
 taking nearly 91bs of beef freed from fat and bone, discharged 
 190 grammes (more than six ounces) of urea daily, and while 
 living on little more than lib of potatoes and half a pound of 
 fat, excreted not more than from 6 to 8 grammes (or from a 
 drachm and a half to two drachms). 
 
 He finds that the use of gelatin as food increases the 
 quantity of urea to a great extent ; but he believes that the 
 additional urea is merely a product of the decomposition of 
 the gelatin in the blood, without its having contributed to 
 form any tissue of the bofly. 
 
 We are indebted to the same observer for the knowledge 
 of the fact that common salt exerts an unquestionable influ- 
 ence in augmenting the excretion of urea, in consequence 
 doubtless of its augmenting the rapidity of metamorphic action 
 in the tissues. 
 
 The researches of Heller, Bocker, and Julius Lehmann show 
 that alcohol, tea, and coffee (especially the empyreumatic 
 aromatic substance contained in it) diminish the daily quan- 
 tity of urea. 
 
 Of exer- Strong bodily exercise increases the quantity of urea very 
 
 else. 
 
UREA. 45 
 
 considerably. All observers, excepting Kummel, agree on tins 
 point. Lehmann found that while during his ordinary mode 
 of living he excreted about 32 grammes, the amount rose to 
 36 and even to 37*4 grammes after severe exertion. His 
 experiments are confirmed by those of Beigel, quoted in the 
 preceding page, who found that on a full animal diet exer- 
 cise caused an augmentation of the urea amounting to 6*16 
 grammes. 
 
 Little is definitely known regarding the power of remedial 9 f mecli ~ 
 agents in modifying the amount of urea, except that Liquor 
 potassse has been decisively proved, by the experiments of 
 Dr. Parkes, to increase its quantity. The experiments of 
 Bocker, Beigel, and others on this subject, are too vague and 
 uncertain in their results to call for special notice. 
 
 Our information on the effect which diseases produce on Of diseases, 
 the amount of urea is not very satisfactory. Heller observed 
 the greatest quantity of urea in meningitis, the whole urine 
 solidifying in a few minutes into a crystalline magma on 
 the addition of concentrated nitric acid. According to the 
 same observer, the urea is in excess during the stage of 
 exudation, but diminishes during resorption, in pneumonia, 
 in pleuritis, and in acute rheumatism, especially if endocarditis 
 be simultaneously present : in the beginning of typhus there 
 is an augmentation of the urea, but not so great as in the 
 above-mentioned diseases. In most renal disorders, and in 
 the chronic neuroses, there is a diminution of this constituent. 
 Dr. A. Vogel, in an excellent memoir " On the Augmentation 
 and Diminution of Urea in Diseases," which is based upon 182 
 analyses, conducted according to Liebig's method, states that 
 he found the largest amount, 80 grammes, in a case of pyaemia, 
 and the next greatest quantity, 69 grammes, in a case of 
 typhus fever. It appears, from his investigations, that in 
 typhus fever the excretion of urea is increased only so long as 
 the febrile symptoms continue, and that when the fevdr is 
 over the quantity of urea falls below the normal amount, not- 
 
46 PHYSIOLOGICAL CHEMISTRY. 
 
 withstanding the increased quantity of nitrogenous food.* In 
 Blight's disease (affecting both kidneys) the urea often falls 
 to one-third or one-fourth of the normal quantity; and in 
 polydipsia hysterica (although the amount of urine is very 
 great) the total quantity of urea is much diminished. The 
 smallest quantity observed by Vogel occurred in a case of 
 carcinoma of the liver with great atrophy, when it was once 
 found to fall below 7 grammes. 
 
 Its presence It is only recently that the presence of traces of urea in 
 healthy blood has been satisfactorily established ; the rapidity 
 with which it is removed by the kidneys, rendering its certain 
 detection, even in five or six pounds of blood, by no means 
 easy.f It is abnormally increased in cases in which the 
 functions of the kidneys are imperfectly executed, especially 
 in Bright's disease, renal ischuria, and cholera. 
 
 It is a normal constituent of the fluids of the eye (Millon, 
 Wohler), and of the liquor amnii (Scherer). 
 
 Urea has been in vain sought for in healthy muscular tissue, 
 where, if the theory be correct that it is mainly formed by the 
 disintegration of that structure, we should especially expect to 
 find it. It has, however, been found by Buhl and Voit, and 
 likewise by von Bibra J, in considerable quantity in the mus- 
 cular tissue of cholera patients. In one case von Bibra found 
 O317# of urea in the dried tissue of the glutseal muscles. 
 
 Whenever the urea is not duly separated by the kidneys we 
 find it in most of the animal fluids, especially in the sweat 
 and in serous exudations : under these circumstances it likewise 
 occurs in lesser quantity in the saliva, the bile, and vomited 
 matters. 
 
 * The Gulstonian Lectures of Dr. Parkes, " on Fever," published in the 
 " Medical Times " in the Spring of 1855, contain much information on this 
 point; indeed, they embrace the whole Chemistry of Fever. 
 
 f Since the above paragraph was written, M. Picard has shown that Liebig's 
 volumetric method of testing quantitatively for urea may be applied to the 
 blood, from which it will separate the smallest traces. He found in the dog 
 that the blood of the renal artery yielded 0.03 G5 of urea, while that of the 
 renal vein yielded only 0'0186g. Comp. Rend. Sept. 8th, 1856. 
 Ann. d. Ch. u. Pharm. 1855, vol. xciv. p. 211. 
 
UREA. 47 
 
 (43.) It is well known that the origin of urea is still a Its origin. 
 qucBstio vexata amongst chemists and physiologists ; one party, 
 including the names of Liebig, Bischoff, and others, holding 
 that the urea is solely a product of the metamorphosis of the 
 nitrogenous tissues ; whilst the other party, which ranks 
 amongst its supporters Lehmann, Frerichs, and (more espe- 
 cially) Bidder and Schmidt, maintain that the formation 
 of urea is dependent upon two factors, one of which is 
 variable, namely, the amount of assimilated histoplastic or 
 albuminous food ; while the other is constant, namely, the 
 necessary consumption of the albuminous tissue when the 
 animal is fasting.* 
 
 It admits of no doubt that urea is formed from the nitro- 
 genous constituents of the organism, its artificial produc- 
 tion f from such substances affording the strongest evidence 
 on that point : in addition to which we may add the facts 
 observed by Lassaigne, Scherer, and others, of urea being 
 contained in the urine excreted after nearly three weeks' 
 starvation. As the metamorphosis of tissue occurs with the 
 greatest activity in the muscular system, and as, further, 
 increased bodily exercise augments the amount of urea, we 
 are justified in regarding the urea as formed for the most 
 part from the worn-out muscular fibres, although it is most 
 
 * Fuhrer and Ludwig, in a recent memoir " On the Physiological Compen- 
 sation of the Spleen, and on the Sources of Urea," of which I have only seen 
 an abstract in Schmidt's Jahrbiicher, maintain a third view ; namely, that the 
 urea, during the normal nutrition of the body, especially depends on the solu- 
 tion of the morphotic elements of the blood (especially the haematocrystalline), 
 and that all superfluous food causes an excessive formation and destruction of 
 these elements. 
 
 j- The artificial formation of urea from cyanate of ammonia is fully de- 
 scribed in all our more recent treatises on Organic Chemistry. Its formation 
 by oxidation, from uric acid, and allantoine, are noticed in our remarks on those 
 substances. Dumas has recently announced (Comp. Rend. Sept. 8, 1856) 
 that Bechamp, a young French chemist, has succeeded in transforming albu- 
 men into urea, by digesting it with a solution of permanganate of potash, at a 
 temperature of 176 F. This result leads to the conclusion that the urea is 
 naturally formed by a slow combustion of the albumen of the blood. 
 
48 PHYSIOLOGICAL CHEMISTRY. 
 
 probable that other vital tissues may contribute to the general 
 amount. Whether it is formed in the organic particles at the 
 moment of their disintegration, or whether it is first formed in 
 the blood, is a point which cannot be considered as decisively 
 established; but it is most probable that the latter is the 
 correct view, because Liebig, in his experiments on large 
 quantities of muscular juice, could not detect in it any trace 
 of urea, although he found substances from which he could 
 produce it artificially. It seems, therefore, almost certain 
 that these substances (creatine, creatinine, and probably 
 inosic acid) are decomposed in the blood, by the action of 
 the alkalies and of free oxygen, into urea and other matters 
 to be excreted. Moreover, the view that the urea is formed 
 in the blood is supported by well-known experiments, showing 
 that gelatin, glycine, alloxantin, theine, and other sub- 
 stances, which it is impossible to suppose can form tissue, are 
 converted into urea and other matters, as is evidenced by the 
 fact that this substance occurs in a perceptibly increased 
 quantity in the urine, soon after any of the above-named 
 substances have been swallowed. 
 
 Lehmann's view that the urea is in part formed from assimi- 
 lated nitrogenous food which has never entered into the sub- 
 stance of the tissues, is chiefly based on the following facts : (1.) 
 on the extent to which its amount is increased by the free use of 
 animal food (nature in this way getting rid of the superfluous 
 plastic material along with that which has become unfit for 
 use) ; and (2.) on the circumstance first noticed by Frerichs, 
 but mainly established by the investigations of his opponent, 
 Bischoff, that the use of gelatin and gelatinous food so 
 rapidly increases the quantity of urea, that we are compelled 
 to believe that these nitrogenous matters are at once directly 
 oxidised in the blood, without having entered into the com- 
 position of the tissues; and if these, why not the protein- 
 bodies also ? (We should observe that Bischoff himself fully 
 grants that the gelatin is directly converted in the blood into 
 
ALLANTOINE. 49 
 
 urea, but, he adds, it is never a natural article of food, nor is 
 it ever found as a normal constituent of the blood). 
 
 When treating of uric acid we shall show that in all pro- 
 bability a great part of the urea, separated by the kidneys 
 from the blood, had previously existed in the form of that 
 organic acid. 
 
 Whether urea exerts any special influence on the fluids of 
 the eye is a question that no one has yet attempted to 
 answer. 
 
 (44.) Allantoine, which is always associated with one atom Allantoine. 
 of water, forms colourless, hard, glistening, four-sided prisms. 
 (See Plate II. Jig. 6.) It dissolves in 160 parts of cold water, 
 and more readily in hot water : it is soluble in hot alcohol, 
 from which it crystallises on cooling, and is insoluble in ether. 
 
 When exposed to the action of concentrated alkalies it 
 takes up water, and is resolved into oxalic acid and ammonia. 
 
 Boiling nitric acid decomposes it into urea and allantoic 
 acid, C 10 H 7 N 4 9 : moreover, on exposing allantoine to fermen- 
 tation with a little yeast, urea is also formed in association 
 with various ammonia-salts. 
 
 Allantoine is precipitated by nitrate of protoxide of mercury 
 in precisely the same manner as urea : hence, if this substance 
 were present in urine, it would interfere with the application 
 of Liebig's method. It moreover reduces the oxide of copper : 
 hence it would interfere with Trommer's test for sugar. 
 
 There is no special test for the detection of allantoine, but 
 we may attach considerable weight to the determination of 
 the form of its crystals. 
 
 This substance exists naturally in the allantoic fluid, as 
 likewise in the urine of calves as long as they continue to 
 suck ; when they begin to take vegetable food it disappears, 
 and is replaced by hippuric acid. Frerichs and Stadeler have 
 recently shown that it may occur in the urine in cases of 
 impeded respiration ; they found it in the urine of two dogs 
 the action of whose lungs was artificially impeded ; and there 
 
 
 
50 PHYSIOLOGICAL CHEMISTRY. 
 
 was a doubtful trace of it in the urine of a man with disease 
 of the respiratory organs. 
 
 It is sufficiently obvious from the positions and cireum- 
 . stances in which it occurs, that allantoine is a product of the 
 metamorphosis of the animal tissues. Under certain con- 
 ditions with which we are as yet unacquainted, it probably 
 constitutes an intermediate stage in the disintegration of tissues 
 between uric acid and urea : at all events we know that al- 
 lantoine is one of the products of oxidation of the above-named 
 acid (see 58), and that under the influence of oxidising 
 agents (nitric acid and yeast), it yields urea as one of its 
 products. 
 
 Hypoxan^ (45.) Hypoxanthine, in a state of purity, exists as a crystal- 
 line powder, difficult of solution in cold water, but dissolving 
 more readily in boiling water (1 part in 180). If its solution 
 in nitric acid be evaporated, there remains an intense yellow 
 residue, which when treated with potash assumes a brilliant 
 reddish yellow colour. 
 
 This substance was discovered by Scherer in the splenic 
 juice both of the ox and of man, and in the muscular tissue 
 of the heart. It has subsequently been found by Gerhard (a 
 pupil of Scherer's) in the blood of oxen, and by Scherer 
 himself (in considerable quantity) in human blood in a case 
 of leucaemia. Grorup-Besanez, who has carefully examined 
 many of the glandular tissues, has not only confirmed 
 Scherer's discovery of its existence in the spleen, but he also 
 found it in the thymus and thyroid glands. Scherer has,- 
 during the present year (1856), announced its discovery, in 
 association with uric acid, in varying quantities in every 
 human liver that he has .examined : and in the pancreas it is 
 so abundant, in association with leucine and tyrosine, that he 
 regards this gland as a good source for yielding all these 
 bodies. Nothing can as yet be decided regarding its physio- 
 logical importance. 
 Xanthine. (46.) Xanthine, which was formerly known as uric oxide, 
 
CYSTINE. 51 
 
 is not crystallisable. It is only found in urinary calculi, of 
 which it is a very rare constituent, and nothing is known of the 
 conditions under which it is produced. 
 
 (47.) Guanine occurs in the excrements of certain sea-fowl Guanine. 
 and of spiders. It has likewise been found as a glandular 
 product in the river cray-fish and the fresh-water mussel. 
 It receives its name from its being first discovered in guano. 
 
 (48.) Myeline is a name given by Virchow to a substance Myeline. 
 which he has discovered in diseased lungs, in an hepatic cyst, 
 in healthy and diseased spleens, &c. He has given it this 
 name from its resemblance to the nerve-medulla. Its che- 
 mical nature seems extremely doubtful. 
 
 (49.) Cystine occurs, in a state of purity, in colourless, Cystine. 
 transparent, hexagonal plates or prisms. (See Plate II. fig. 7.) 
 It is insoluble in water and alcohol, but dissolves in the 
 mineral acids (with most of which it forms salt-like com- 
 pounds), in oxalic acid, in the fixed alkalies and their carbo- 
 nates, and in ammonia; but not in the carbonate of am- 
 monia. It is best thrown down from its acid solutions by 
 carbonate of ammonia, and from its alkaline solutions by acetic 
 acid. The peculiar form of the crystals of this substance 
 suffices at once to distinguish it from all other bodies, except- 
 ing, perhaps, uric acid, which I have occasionally seen to 
 assume a nearly similar shape.* 
 
 Cystine is a rare constituent of urinary calculi. (In 129 
 specimens Taylor only found 2 containing it.) It has occa- 
 sionally been found as a urinary sediment, mixed with .urate 
 of soda ; and in such cystine-containing urine an additional 
 precipitate may often be obtained (according to Grolding Bird) 
 by the addition of acetic acid. Virchow has recently (1856) 
 
 * That cystine occasionally crystallises in other forms than hexagonal plates 
 is obvious, from an observation recently made by Virchow, who found a large 
 renal calculus of cystine, composed of very acute rhombic tablets or broader 
 rhombic prisms in a state of aggregation. Thaulow had, I believe, previously 
 noticed this peculiarity. 
 
 E 2 
 
52 PHYSIOLOGICAL CHEMISTRY. 
 
 obtained unquestionable evidence of the presence of cystine 
 in the aqueous decoction of the liver of a typhus patient. 
 
 Nothing is known regarding the origin of cystine. As in 
 his investigation of the glandular structures Cloetta sometimes 
 found taurine and sometimes cystine in the kidneys, he infers 
 that the latter is formed from the former. In its chemical 
 composition it differs from all other animal bodies, with the 
 exception .of taurine, in the enormous quantity of sulphur 
 which it contains (26*7--) ; no other substances in which this 
 Clement occurs, as albumen, casein, fibrin, &c., containing 
 more than 2-g-. It is not impossible that when cystine occurs 
 in the urine, the kidneys may be acting vicariously for the 
 liver. This view is borne out by the recent observations of 
 Virchow and Cloetta to which we have alluded. 
 
 Taurine. (50.) Taurine crystallises in colourless, perfectly transparent 
 
 six-sided prisms with pointed extremities (see Plate II. fig. 8.) ; 
 it dissolves readily in water, slightly in spirit, and is insoluble 
 in absolute alcohol and ether. It dissolves unchanged in the 
 mineral acids, but it neither combines with them nor with 
 bases. Strecker has recently succeeded in forming taurine 
 artificially from isethionate of ammonia, NH 4 . C 4 H 5 . 2S0 
 (which = C 4 H 7 N0 6 S 2 + 2HO, and, therefore, only differs from 
 taurine by two equivalents of water), by exposure to a high 
 temperature. (Isethionic acid is formed by the action of an- 
 hydrous sulphuric acid on alcohol with the aid of heat.*) 
 
 This substance exists preformed in the normal bile of most 
 animals, as an adjunct to the cholic acid, which has been 
 already described. (See 25.) It is only in decomposed or 
 morbid bile that it occurs in an isolated form, and thus we 
 can account for its occasional detection in the contents of the 
 intestines and in the excrements. After the removal of the 
 mucus all the sulphur of the bile is due to the taurine (which 
 contains 25'6-g- of that element). Cloetta, in his investigations 
 
 * See Gregory's "Handbook of Organic Chemistry," 4th ed. 1856, p. 227. 
 
TAURINE. 53 
 
 regarding the chemistry of the glands, finds taurine in the 
 lungs and sometimes in the kidneys. Further observations 
 on the occurrence of taurine in the animal fluids will be 
 found in 55. in our remarks on taurocholic acid. 
 
 It is still a doubtful point whether taurine be actually 
 formed in the liver, or whether that gland merely separates it 
 from the blood in a similar manner to the separation of the 
 urea by the kidneys ; the former is the more probable view, for 
 the reasons given in 166. regarding the formation of the bile. 
 Strecker's discovery renders it almost certain that the sulphur 
 exists in taurine in an oxidised state ; a view that is further 
 confirmed by the fact that it cannot be detected by the 
 ordinary fluid oxidising agents : hence its formation must at 
 all events be regarded as dependent on a process of oxidation ; 
 and, as we shall subsequently see, when treating of the bile, 
 the liver is most probably the seat of its production. 
 
 Valenciennes and Fremy, in their recent memoir (< On the 
 Composition of the Muscles in the Animal Series," found in 
 the muscular tissue of all the molluscs that they examined a 
 substance which, in both its crystallographic character and 
 its chemical composition, seems to be identical with taurine ; 
 and they believe that these results will modify the view gene- 
 rally held, that taurine originates in the liver, and that it will 
 be found to be much more abundant in the animal organisa- 
 tion than is generally supposed. The researches of Cloetta 
 (1856) strongly confirm this view. 
 
 (50*.) TABULAR VIEW OF THE COMPOSITION OF THE NITROGENOUS 
 
 BASES. 
 
 Glycine, C 4 H 5 N0 4 , Sarcosine, C 6 H 7 N0 4 , 
 
 Carbon . . 32-00 Carbon . . 40-45 
 
 Hydrogen . . 6-67 Hydrogen . . 7-86 
 
 Nitrogen . . 18-67 Nitrogen . . 15-73 
 
 Oxygen . . 42*66 Oxygen . . 35-96 
 
 E 3 
 
54 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Leucine, C 12 H 13 N0 4 . 
 
 Carbon . . 54-96 
 
 Hydrogen . . 9-92 
 
 Nitrogen . . 10-68 
 
 Oxygen . . 24*44 
 
 Creatine, C g 
 
 fly*gO r 
 
 Carbon . ' 
 
 . 36-64 
 
 Hydrogen . 
 Nitrogen . 
 Oxygen 
 
 6-87 
 . 32-06 
 . 24-43 
 
 Urea, C 2 H 4 N 2 2 . 
 Carbon ; >: ; 20-000 
 Hydrogen . . 6-666 
 Nitrogen . . 46-667 
 Oxygen . , 26-667 
 
 Hypoxanthine, C 10 H 4 N 4 2 . 
 
 Carbon . . 44-13 
 
 Hydrogen . . 2-94 
 
 Nitrogen . . 41-17 
 
 Oxygen . . 11-76 
 
 Cystine, C 6 H 6 NS 2 4 . 
 
 arbon . . 30-000 
 
 Hydrogen . . 5-000 
 
 Nitrogen . . 11-666 
 
 Sulphur . . 26-667 
 
 Oxygen .. , 26-667 
 
 Tyrosine, C 18 H n N0 6 . 
 
 Carbon , . 59-67 
 
 Hydrogen . . 6-08 
 
 Nitrogen . . 7-73 
 
 Oxygen . . 26-52 
 
 Creatinine, C 8 H 7 N 3 2 . 
 
 Carbon T 'V' ' . 42-48 
 
 Hydrogen . . 6-19 
 
 Nitrogen . . 37-17 
 
 Oxygen . . 14-16 
 
 Allantoine, C 8 H 5 N 4 0^. HO. 
 Carbon f . . 30-38 
 Hydrogen . . . 3-16 
 Nitrogen . . 35-44 
 Oxygen , . 25-32 
 Water . . , 5-70 
 
 Xanthine, C 10 H 4 N 4 4 . 
 
 Carbon , . 39-47 
 
 Hydrogen . 2-63 
 
 Nitrogen . . 36*84 
 
 Oxygen . v r _ v , . 21-06 
 
 Taurine, C 4 H 7 NS 2 6 . 
 
 Carbon . . 19-20 
 
 Hydrogen , . 5-60 
 
 Nitrogen . . 11-20 
 
 Sulphur . . 25-60 
 
 Oxygen . . 38-40 
 
55 
 
 CHAPTER IIL 
 
 NITROGENOUS CONJUGATED ACIDS. 
 
 (51.) UNDER this head we have to consider the following 
 acids, which we divide into three groups : 
 
 fHippuric acid . . . . C 18 H 8 N0 5 . HO. 
 
 I GKycocholic acid . . . C 52 H 42 NO U .HO. 
 
 1 Hyocholic acid .... C 54 H 43 N0 10 . HO. 
 
 iTaurocholic acid . . . C 52 H 45 NS 2 ]4 . HO. 
 
 Inosic acid C 10 H 6 N 2 10 . HO. 
 
 I 
 
 f Uric acid . .-h^< . C 10 H 4 N 4 6 . 
 
 Pneumic or Pulmonic acid 
 
 \Cynuric acid . ^ . . ? 
 
 The first four of these acids are placed by themselves in 
 the first group, because they especially present the leading 
 characteristic of conjugated acids ; that is to say, when treated 
 with concentrated acids or with alkalies, they resolve themselves 
 into a nitrogenous body, which we regard as the adjunct, and 
 into a non-nitrogenous acid. 
 
 Hippuric acid has usually been regarded as benzoic acid Their theo- 
 conjugated with glycine, because, when digested with concen- 
 trated mineral acids, it resolves itself into those two sub- 
 stances (C 18 H 8 N0 5 + 2HO = C 4 H 5 N0 4 + C I4 H 5 3 ); but since 
 it has been discovered (by Strecker) that with nitrous acid it 
 yields the benzoglycic acid noticed in the note to 24., it 
 seems not improbable that it is a true amide of benzoglycic 
 acid, H 2 N.C 18 H 7 6 a view of its composition which is in 
 full accordance with its various decompositions, the only diffi- 
 
 E 4 
 
56 PHYSIOLOGICAL CHEMISTRY. 
 
 culty being how it can be an amide-compound and still retain 
 acid properties. We do not yet know whether a similar rela- 
 tion holds good in glycocholic and hyocholic acids, which also 
 yield glycine when treated with acids or alkalies ; the ordinary 
 view is that they are acids conjugated with glycine, the former 
 having the theoretical formula C 4 H 3 N0 2 . C 48 H 39 9 , and the 
 latter C 4 H 3 N0 2 . C 50 H 40 8 . As taurocholic acid resolves itself, 
 when treated with acids, into taurine and choloidic acid, we 
 regard it as cholic acid conjugated with taurine, and as being 
 represented by the formula C 4 H 6 NS 2 5 . C 48 H 39 9 . 
 
 The second group has not been sufficiently studied to 
 enable us to hazard an opinion regarding their theoretical 
 composition. Even the empirical formula for pneumic acid 
 has not yet been determined. 
 
 We have placed uric and cynuric acids together, but it is 
 still uncertain to what group the latter acid belongs ; in its 
 chemical composition uric acid is closely allied to the two 
 neutral bodies hypoxanthine and xanthine, as is obvious from 
 their formulae : 
 
 Hypoxanthine , , . C 10 H 4 N 4 2 . 
 Xanthine .... C 10 H 4 N 4 4 . 
 
 Uric acid /J . . . C 10 H 4 N 4 6 ; 
 
 so that it would seem as if these three compounds represented 
 different stages of oxidation of the same radical, C 10 H 4 N 4 . 
 Hippuric (52.) Hippuric acid in a state of purity occurs in regular 
 
 white or semitransparent rhombic prisms, with pointed ex- 
 tremities (see Plate 111. fig. 1); it is devoid of odour, has 
 a slightly bitter taste, dissolves readily in boiling water and 
 in alcohol, and less freely in cold water and in ether; its 
 solutions strongly redden litmus. When gently heated in a 
 test-tube it fuses, without loss of water, into an oily liquid, 
 which, on cooling, solidifies into a crystalline milk-white 
 mass ; on the application of a stronger heat there is produced 
 a crystalline sublimate of benzoic acid and benzoate of am- 
 
HIPPURIC ACID. 57 
 
 monia, while red oily drops are at the same time formed, which 
 have a peculiar aromatic odour (resembling that of the Tonka- 
 bean or new hay), solidify on cooling, and are insoluble in 
 water, but dissolve in spirit and in ammonia : on exposing 
 the acid to a yet stronger heat, an intense odour of prussic 
 acid is developed, and a porous carbonaceous mass remains. 
 
 Dessaigne has made the interesting observation that hip- 
 puric acid may be artificially formed, under certain conditions, 
 by the mutual action of chloride of benzoyl and the compound 
 of oxide of zinc and glycine, represented by the formula 
 C 4 H 5 N 2 4 . ZnO. He expresses the change that ensues by the 
 following equation : 
 
 C 4 H 5 N 2 4 .ZnO + C 14 H 5 2 .C1 2 = C 18 H 9 N 2 6 + ZnCl 2 + HO. 
 
 We have already noticed the resolution of hippuric acid, 
 when heated with strong mineral acids, into benzoic acid and 
 glycine, and likewise the mode in which benzoglycic acid is 
 formed from it by the action of nitrous acid. 
 
 In fermenting and putrefying fluids hippuric acid is con- 
 verted into benzoic acid and other products. 
 
 The only substance with which hippuric acid is likely to be 
 confounded is benzoic acid contaminated with pigment and 
 other nitrogenous matters. They may, however, be distin- 
 guished by the following points : (1.) their different behaviour 
 when exposed in a test-tube to the action of heat ; (2.) their 
 different behaviour with ether; hippuric acid is far less 
 soluble in ether than benzoic acid, and crystallises from hot 
 saturated solutions in needles or prisms, while benzoic acid 
 crystallises in scales ; and (3.) a microscopic examination of 
 the form of the crystals. 
 
 When treating of uric acid we shall show how it may be 
 distinguished from hippuric acid. 
 
 Hippuric acid occurs in large quantities in the urine of the its occur- 
 herbivorous mammals ; it does not, however, exist in the urine r 
 of the calf until it is weaned ; allantoine, uric acid, and urea 
 
58 PHYSIOLOGICAL CHEMISTRY. 
 
 being found in this fluid till the young animal has recourse to 
 vegetable food. It is a normal constituent of human urine 
 during a mixed or vegetable diet ; but Liebig's statement that 
 its quantity is about the same as that of uric acid is very far 
 from being generally true. It not unfrequently happens that 
 8 or 10 ounces of healthy urine will only yield a few micro- 
 scopic crystals, especially if food has not been taken for 12 or 
 15 hours. The following experiments performed by Heller, 
 in conjunction with a friend, must be confirmed before we 
 accept them. After determining their normal quantity of 
 uric acid, Heller lived for a week on wheat and rye bread, 
 and his friend solely on rye bread (of which they took as much 
 as they needed), and water was their only drink. The uric 
 acid soon began to diminish, and to be replaced by hippuric 
 acid, while the quantity of urea was not materially affected. 
 At the end of the week there was a large quantity of hippuric 
 with a mere trace of uric acid in Heller's urine ; while in that 
 of his friend the hippuric acid completely replaced the uric 
 acid, not even a trace remaining. During the next week, 
 when they were living on a mixed diet (including flesh), the 
 process was reversed; the 'hippuric acid vanishing and the 
 uric acid returning more rapidly than it had disappeared. It 
 would thus seem, in opposition to the well-known experi- 
 ments of Lehmann*, that the use of a purely vegetable diet 
 causes the disappearance of uric acid and the simultaneous 
 abundant formation of hippuric acid. 
 
 Eoussin f has ascertained that, in the case of the horse? the 
 proportions of hippuric acid vary directly with the work, and 
 inversely with the urea ; that is to say, that over-worked horses 
 produce much hippuric acid and comparatively little urea; 
 and he believes that respiratory activity and the employment 
 of muscular force transform urea into hippuric acid. This 
 seems a most improbable view. 
 
 * These experiments are described in the chapter on " The Urine." 
 f Silliman's Journal, 1856, vol. xxii. p. 102. 
 
HIPPURIC ACID. 59 
 
 Hippuric acid does not exist in the urine of carnivorous 
 animals. Lehmann has found it in the renal secretion of the 
 common European tortoise. 
 
 In various forms of disease there is a great augmentation of 
 hippuric acid, especially in the strongly acid urine which is 
 frequently passed in fevers and in inflammatory diseases, and 
 in diabetic urine. 
 
 Hippuric acid (probably in combination with soda) has re- 
 cently been detected in the blood of oxen and in morbid 
 human blood. 
 
 Schlossberger has obtained unquestionable evidence of the 
 presence of this acid in the cutaneous scales in a well-marked 
 case of ichthyosis : this result is the more singular, since 
 Schottin has ascertained that benzoic acid, when administered 
 to a healthy man, appeared unchanged in the sweat, and not 
 in the form of hippuric acid, as in the urine, 
 
 Nothing very definite can be stated regarding the substances Its origin, 
 from which hippuric acid is formed, or the seat of its forma- 
 tion. As, however, Gruckelberger's experiments have shown 
 that the nitrogenous tissues, when treated with nitric acid, 
 yield benzoic acid and hydruret of benzoyl (oil of bitter 
 almonds), there is every reason to believe that they yield 
 similar products of decomposition during the gradual oxida- 
 tion which they undergo in the animal body. The benzoic 
 acid thus formed may be supposed to unite in the nascent 
 state with glycine, which is most probably, like urea, a 
 common product of the decomposition of nitrogenous sub- 
 stances. 
 
 (53.) Glycocholic acid* occurs in the form of such ex- Glyco- 
 tremely delicate white needles that when magnified 300 times 
 
 * I have adhered throughout this volume to Lehmann's nomenclature of 
 the biliary acids. His glycocholic acid is Strecker's cholic acid. The glycocho- 
 late of soda, with an admixture of the taurocholate, seems to be equivalent to 
 the biline of Berzelius, and the bilate of soda of Liebig, Plattner, &c. This 
 acid was originally discovered in 1826 by Gmelin, who gave it the name of 
 cholic acid. 
 
60 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Its occur- 
 rence. 
 
 Hyocholic 
 acid. 
 
 they have scarcely any perceptible diameter. (See Plate III. 
 fig. 2.) It is difficult of solution in cold water, but dissolves 
 more readily in hot water; it is freely soluble in spirit, 
 slightly in ether. The cold watery solution has a sweet and 
 somewhat bitter taste, and reddens litmus. 
 
 If glycocholic acid be boiled for a prolonged time with a 
 solution of potash or with baryta water it takes up 2 atoms 
 of water and becomes resolved into the non-nitrogenous cholic 
 acid, C 48 H 39 9 . HO, and glycine, C 4 H 5 N0 4 . With sulphuric 
 acid and sugar (or acetic acid) it yields the same reaction as 
 cholic acid.* 
 
 Grlycocholate of soda, NaO . C 52 H 42 NO n , separates from its 
 alcoholic solution, on the addition of ether, in large, glistening, 
 white clusters of radiating needles (see Plate III. fig. 3.), but 
 does not crystallise from an aqueous or spirituous solution, 
 Grlycocholate of potash behaves in a similar manner. The so- 
 called crystallised bile is a mixture of these two salts. 
 
 It is by no means easy to distinguish the various acids of 
 the bile and their derivatives from one another, unless we 
 have a considerable amount of matter to work upon ; their 
 different crystalline forms, however, considerably aid us, when 
 the substances are separated in a state of tolerable purity. 
 
 Grlycocholic acid, in combination with soda, is the main 
 constituent of ox-gall ; it is, however, also found, although in 
 smaller proportions, in the bile of most other animals, except- 
 ing in that of the pig, where it is replaced by hyocholic acid. 
 It very soon undergoes decomposition in the intestinal canal. 
 Its seat of formation is, most probably, the liver. 
 
 (54.) Hyocliolic acid has as yet been found only in the bile 
 of the pig, where it exists in combination with soda, potash, 
 and a little ammonia. It is not crystallisable, and presents 
 considerable similarity to choloidic acid. When treated with 
 concentrated mineral acids, it yields glycine and a resinous 
 acid ; but its rational formula is not definitely determined. 
 
 * See the description of Pettenkofer's test, in 25. 
 
TAUROCHOLIC ACID. 61 
 
 (55.) Taurocholic add * has never been obtained in a state Taurocho- 
 of perfect purity, glycocholic acid being always more or less 
 present. It exists as a white, perfectly amorphous, very 
 hygroscopic, and intensely bitter powder, which dissolves 
 readily in water and spirit, but is insoluble in ether. Its 
 solutions have a less acid reaction than those of glycocholic 
 acid. It dissolves fats, fatty acids, and cholesterin freely. 
 When boiled with mineral acids, it becomes resolved, as has 
 been already mentioned, into taurine, C 4 H 7 NS 2 6 ,and choleidic 
 acid, C 48 H 39 9 ; when boiled with alkalies, into taurine and 
 cholic acid ; and when treated with sulphuric acid and sugar, 
 it gives the same reaction as the other essential acids of the 
 bile. 
 
 The alkaline taurocholates dissolve readily in water and in 
 alcohol, but are insoluble in ether. Nitrogenous substances, 
 as, for instance, mucus, set up a process of decomposition in 
 solutions of alkaline taurocholates, which may be readily 
 ascertained by the circumstance that the solutions then be- 
 come precipitable by dilute acids. The products which are 
 formed are taurine, alkaline cholates or choloidates, and pro- 
 bably certain combinations of these substances with taurocholic 
 acid that had escaped decomposition. 
 
 There is no very easy test for the detection of taurocholic 
 acid, when it is present in only a small quantity. 
 
 Taurocholic acid, in combination usually with soda, occurs Its occur- 
 in the bile of man, the ox, the fox, the bear, the sheep, the 
 wolf, the dog, the goat, certain birds, the frog, the boa 
 anaconda (in which animal it seems to be unassociated with 
 any other biliary acid), and certain fresh-water fishes. 
 
 It has been detected in the blood, in transudations, and in 
 the urine in cases of suppressed excretion of bile. 
 
 * Lehmann's taurocholic acid is identical with the choleic acid of its discoverer, 
 Demar9ay, in 1838. Strecker, in his important investigations in reference to 
 the bile, retains Demarcay's original term. 
 
62 PHYSIOLOGICAL CHEMISTRY. 
 
 This acid soon undergoes decomposition in the intestinal 
 canal, so that we there find taurine, free choloidic acid, &c. 
 
 Taurocholic acid, like glycocholic acid, is most probably 
 originally formed in the liver : but we shall return to the con- 
 sideration of the formation and uses of these acids when we 
 treat of the bile. 
 
 Inosic acid. (56.) Inosic acid exists in the form of a syrupy fluid, which 
 dissolves readily in water, but is insoluble in alcohol and 
 ether ; it reddens litmus strongly, and possesses an agreeable 
 taste of the juice of meat. The alkaline inosates are soluble 
 in water, and crystallisable, and when heated on a platinum 
 spatula diffuse a powerful odour of roasted meat. 
 
 It has as yet been found only in the muscular juice. 
 Nothing is known regarding its rational formula or its mode 
 of formation. From the great quantity of oxygen which it 
 contains (43'7-g-), it must be regarded as a product of the de- 
 composition of effete tissues. 
 
 Pneumic (57.) Pneumic or Pulmonic acid crystallises in oblique 
 
 rhombic prisms, is extremely glistening, and refracts light 
 strongly. It dissolves readily in water, is insoluble in cold 
 but dissolves in boiling alcohol, is insoluble in ether, forms 
 crystallisable salts with bases, and contains not only carbon, 
 hydrogen, and oxygen, but also nitrogen and sulphur. 
 
 It appears to be a constituent of the pulmonary tissue of all 
 mammals. Verdeil *, its discoverer, obtained about five cen- 
 tigrammes (about 0*8 of a grain) from the lungs of a perfectly 
 healthy woman, who was guillotined. Morbid conditions 
 appear to occasion an augmentation rather than a diminution 
 of this substance ; thus, a single lung, from a man with general 
 pneumonia in its second stage, yielded rather more than the 
 two lungs of the guillotined woman. It appears to be formed 
 
 * This acid is fully described in Robin and Verdeil's "Traite de Chimie 
 Anatomique et Physiologique," 1853, vol. ii. pp. 460-467. Since the above 
 paragraph was written, Cloetta seems to'have satisfactorily proved that pneumic 
 acid is merely taurine. (See Ann. d. Ch. u. Pharm. 1856, vol. xcix. p. 296.) 
 
UEIC ACID. 63 
 
 in the substance of the lung itself, and probably bears much 
 the same relation to the pulmonary tissue that creatine does 
 to muscle. Verdeil believes that by decomposing the car- 
 bonates of the blood with which it comes in contact, it con- 
 tributes very considerably to the evolution of carbonic acid, 
 and is thus an important factor in the respiratory process. 
 This, however, requires confirmation. 
 
 (58.) Uric acid *, in a state of purity, occurs as a glistening Uric acid, 
 white powder, or in very minute scales, whose crystalline 
 form, at first sight, appears very variable. Uric acid, when it 
 gradually and spontaneously crystallises from urine, appears in 
 most cases in the whetstone form; that is to say, it forms flat 
 tablets, which resemble sections made with the double knife 
 through strongly biconvex lenses, or rhombic tablets whose 
 obtuse angles have been rounded. As the urinary pigment 
 adheres very tenaciously to uric acid, it is only rarely that 
 these crystals are devoid of colour ; and if we see a crystal of 
 an uncommon form and of a yellow colour, the probability is 
 that it is a crystal of uric acid. On artificially separating 
 uric acid from its salts it usually appears in nearly perfect 
 rhombic tablets, but occasionally in hexagonal plates re- 
 sembling those of cystine; when uric acid crystallises very 
 slowly it forms elongated rectangular tablets, or regular four- 
 sided prisms, the latter being often grouped together in 
 clusters ; we also have barrel-shaped or cylindrical prisms, * 
 and finally saw-like -or toothed crystals. (Plate III. fig. 4.) 
 
 Uric acid is devoid of taste and smell, is very slightly Its chemi- 
 soluble in water (1 part requiring about 15,000 parts of cold t ers. 
 and at least 1800 parts of boiling water for its solution), 
 
 * From an examination of the salts of uric acid by Bensch (Ann. d. Ch. u. 
 Pharm. 1844, vol. li. pp. 189-208), it appears more than probable that we 
 should halve the formula for this acid, and that it should be expressed by 
 C 5 H 2 N 2 O 3 , or C 5 HN 2 O 2 . HO. This change would convert the ordinary urates 
 occurring in urinary sediments into bi-urates, and there are strong objections 
 to altering the nomenclature of common objects with which every student is 
 expected to ~be familiar. 
 
64 PHYSIOLOGICAL CHEMISTRY. 
 
 scarcely more soluble in concentrated hydrochloric acid than 
 in water, and perfectly insoluble in alcohol and ether ; it dis- 
 solves tolerably freely in concentrated sulphuric acid, from 
 which it is precipitated on the addition of water. It is 
 moderately soluble in solutions of the alkaline carbonates, 
 borates, phosphates, lactates, and acetates, abstracting a por- 
 tion of the alkali from these salts, and forming a soluble 
 acid urate. (A solution of ordinary phosphate of soda has, as 
 is well known, a slightly alkaline reaction ; if, however, an 
 excess of uric acid be added, there are formed urate of soda 
 and biphosphate of soda which has an acid reaction. It is 
 thus that Liebig explains the acid reaction of the urine.) 
 
 If uric acid and water be stirred together till a semi-solid 
 mass is formed, and the mixture, after being brought nearly 
 to a boiling heat, be gradually treated with peroxide of lead 
 as long as the brown colour of the oxide continues to dis- 
 appear, there are formed allantoine, urea, and oxalic acid. 
 The allantoine and urea are in solution, and may be separated 
 by crystallisation ; and the oxalic acid is in combination with 
 oxide of lead. The reaction may be expressed symbolically 
 as follows: 
 
 1 eq. uric acid (C 10 H 4 N 4 6 ) + 2 eq. oxygen (20) + 3 eq. 
 water (3HO) = 
 
 1 eq. urea (C 2 H 4 N 2 2 ) + 1 eq. allantoine (C 4 H 3 N 2 3 + 2 eq. 
 oxalic acid (2C 2 3 ). 
 
 This decomposition is important in a physiological point of 
 view, as explaining a probable source of the oxalic acid as 
 well as of the urea occurring in the urine. The ingestion 
 of uric acid, or its injection into the veins, is rapidly followed 
 by an augmentation of urea and of oxalate of lime in the 
 urine* ; a change here takes place within the organism, similar 
 
 * Neubauer's Memoir "On the Decomposition of Uric Acid in the Animal 
 Body," published in the Ann. d. Ch. u. Pharm. 1856, vol. 99, pp. 206222, 
 should be consulted in reference to this mode of formation of urea. 
 
URIC ACID. 65 
 
 to that produced by the oxidising influence of the peroxide 
 of lead. 
 
 Uric acid dissolves in moderately strong nitric acid ; nitrogen 
 and carbonic acid are evolved, and a yellow fluid remains, 
 containing numerous products of decomposition of the acid, 
 which do not at present concern us. On evaporating this 
 solution to dryness there is left a reddish residue (murexide), 
 which, if exposed to the vapour of ammonia, or moistened 
 with a drop of an ammoniacal solution, assumes a splendid 
 reddish purple tint. If the murexide be moistened with a 
 little potash-solution, a beautiful bluish purple tint is evolved. 
 These reactions are manifested when only a very minute trace 
 of uric acid is present. 
 
 (59.) There are several combinations of uric acid which Combina- 
 require notice, as occurring in the urine and in urinary and 
 other concretions, namely, the urates of soda, potash, am- 
 monia, and lime. 
 
 Urate of soda usually appears under the microscope in the 
 form of globules, studded with minute acicular prisms. (See 
 Plate III. Jig. 5.) It is soluble in about 124 parts of boiling 
 water. 
 
 Urate of potash crystallises in needles, and dissolves in 
 about 75 parts of boiling water. The solution is precipitated 
 by hydrochlorate of ammonia and the alkaline bicarbonates. 
 
 Urate of ammonia may be obtained crystallised in extremely 
 delicate needles, but, as usually seen under the microscope, it 
 forms globular opaque bodies, from some points of which 
 minute spikelets project. (See Plate III. fig. 6.) It is 
 moderately soluble in hot water. 
 
 The urate of lime forms a white amorphous powder, soluble 
 in 276 parts of boiling water. 
 
 If hydrochloric, nitric, or even acetic acid be added to a 
 solution of one of these urates, the uric acid is precipitated in 
 a crystalline form: if the solution be very concentrated the 
 crystals are at once separated ; if, on the other hand, it be 
 
 F 
 
66 PHYSIOLOGICAL CHEMISTRY. 
 
 very dilute, 30 or even 50 hours may elapse before the process 
 is completely effected. As a general rule the larger crystals 
 are produced in the more dilute solutions. 
 
 (60.) The crystalline form of uric acid, and its behaviour with 
 nitric acid and ammonia or potash, are sufficient to distinguish 
 it from all other animal substances. If we cannot decide with 
 certainty regarding uric acid from the form of a crystal, we 
 must dissolve it in potash, and add a minute drop of acetic acid ; 
 we shall then always obtain one of the more common forms. 
 
 (61.) Uric acid is a normal constituent of human urine, in 
 which it usually amounts to about 0-1. It occurs in smaller 
 quantity in the urine of carnivorous mammals, and is altogether 
 absent (or is present in mere traces) in that of omnivorous ani- 
 mals (the pig) and vegetable feeders. (Its existence in the urine 
 of the calf while still sucking has been noticed in 51.) The 
 urine of birds, whatever be the nature of their food, and of 
 serpents, consists almost solely of uric acid in combination 
 with alkalies ; which is also found in a similar state of com- 
 bination in the. urine of tortoises, in the excrements of butter- 
 flies, beetles, &c. 
 
 The amount of uric acid in different specimens of human 
 urine varies with the concentration of the fluid ; thus Leh- 
 mann has found as much as 0*8-- in very concentrated morning 
 urine without there being an absolute augmentation of the 
 acid in the urine of 24 hours. 
 
 The absolute quantity of uric acid excreted by an adult 
 man in 24 hours varies, according to Lehmann, from 0-5 to 
 0-9 of a gramme, or from about 8 to 14 grains; it is very 
 little affected by the nature of the food, but seems to be 
 diminished by exercise and increased by perfect repose. Dr. 
 Hammond* found that when taking his ordinary moderate 
 exercise he passed daily 13-7 grains of uric acid; with in- 
 creased exercise the quantity fell to 8*2 grains; and with no 
 
 * American Journal of the Medical Sciences, quoted in the " Monthly 
 Journal of Medical Science," 1855, vol. xx. p. 249. 
 
URIC ACID. 67 
 
 exercise it rose to 24*9 grains. There is an absolute aug- 
 mentation of this constituent when the digestive functions 
 are disturbed, as after the use of indigestible food or alcoholic 
 drinks, and in disorders accompanied with severe febrile 
 symptoms, as, for instance, acute rheumatism ; in these cases 
 the uric acid commonly separates as an amorphous granular 
 sediment of urate of soda, when the urine cools (see Plate III. 
 Jig. 5.) ; and the nature of the sediment may be detected by the 
 readiness with which it disappears when the fluid is warmed. 
 An augmentation of the uric acid associated with the forma- 
 tion of this sediment (which, however, is sometimes only 
 indicative of a great concentration of the urine, and not of 
 an absolute augmentation of the uric acid) is particularly 
 observed in all those conditions of the system which are 
 accompanied with much disturbance of the functions of 
 respiration and circulation; as, for instance, pulmonary em- 
 physema, heart-diseases, enlargement of the liver, &c. 
 
 Free uric acid (Plate III. Jig. 4.) is scarcely ever found in 
 freshly-discharged urine ; in the great majority of cases it is 
 formed from the urate of soda after the exposure of the 
 urine to the atmosphere, by a process of acid fermentation 
 which is described in the chapter on " The Urine." It is 
 in febrile urine that this change takes place the soonest, and 
 that the crystals of uric acid are most rapidly separated. 
 
 Urate of ammonia (Plate III. Jig. 6.) is, moreover, like 
 uric acid, usually a product of the fermentation of the urine ; 
 it scarcely ever occurs except in urine which, by long exposure 
 to the air, has undergone alkaline fermentation. It is only 
 in the fresh alkaline urine of patients with chronic catarrh of 
 the bladder, accompanied with paralysis of that viscus, that 
 we ever find the clusters of this salt shown in the plate. 
 
 Uric acid occurs in very minute traces in the healthy blood ; 
 it is present in excess in cases of gout and Bright's disease, 
 but its quantity is not affected by rheumatism ; it has like- 
 wise been found in excess in cholera, bronchitis, pneumonia, 
 
 F 2 
 
68 PHYSIOLOGICAL CHEMISTRY. 
 
 &c. Dr. Grarrod, to whom we are chiefly indebted for our 
 knowledge of the conditions under which an excess of uric 
 acid occurs in the blood, recommends the following very easy 
 mode of detecting this acid. We have merely to place a little 
 of the serum of the blood in a watch-glass, at the bottom of 
 which lies a fine thread, and to add acetic acid. The uric 
 acid becomes deposited on the thread, and is easily recognised 
 under the microscope by the form of its crystals. This test 
 does not indicate the presence of the acid unless l-40th of a 
 grain be present in 1000 grains of serum, or 1 part in 40,000 ; 
 and as even this quantity is always abnormal, the appearance 
 of the crystals is conclusive as to the existence of uric acid in 
 morbid amount. In order to use the thread-test the serum 
 must be perfectly fresh, for the uric acid soon decomposes, 
 oxalic acid being probably one of its products. 
 
 Uric acid, in combination doubtless with an alkali, is a 
 normal constituent of the aqueous extract of the spleen 
 (Scherer, Grorup-Besanez, Cloetta), of the liver (Scherer, 
 Cloetta), of the lungs (Cloetta), and of the brain (Lerch). 
 
 It has been stated that uric acid, in the form of an alkaline 
 urate, has been found in the sweat in cases of gout ; but this 
 cannot be regarded as an accepted fact. 
 
 Dr. Grarrod has found uric acid in pericardial and peritoneal 
 effusions, and in the fluid of a blister, in cases in which the 
 blood contained an abnormal amount of this substance. 
 
 Urate of soda in a crystallised state usually occurs abun- 
 dantly in the gouty concretions commonly designated chalk- 
 stones. 
 
 (62.) Uric acid, like urea, must be regarded as essentially 
 a product of excretion, but we are ignorant of the exact seat 
 of its formation. Analyses of human urine show that gene- 
 rally the uric acid and the urea stand in an inverse ratio to 
 one another in the same individual ; that is to say, that when 
 the uric acid is increased, there is a corresponding diminu- 
 tion of the urea (see, for example, the experiments of Ham- 
 
URIC ACID. 69 
 
 mond *) ; moreover, the experiments of Wohler and Frerichs, 
 and more recently of Neubauer, show that when large doses 
 either of uric acid or of urate of potash (30 to 40 grains), 
 were given to animals with their food, or injected into their 
 veins, no uric acid could be detected in their urine, but 
 there was an excess of oxalate of lime and urea, the latter 
 exceeding the normal quantity at least fivefold. We thus 
 have tolerably strong evidence that the greater portion of 
 the uric acid in the animal organism undergoes a process of 
 oxidation similar to that which can be artificially induced by 
 peroxide of lead. Assuming, then, that the urea, or that a 
 portion of it, is produced from uric acid, by the partial oxida- 
 tion of the latter, any impediment to this process must cause 
 less urea and more uric acid to be separated by the kidneys ; 
 and hence we see why the amount of uric acid in the urine is 
 increased in fevers and in disturbed conditions of the circulat- 
 ing and respiratory functions generally. Uric acid must be 
 regarded as a substance which stands one degree higher than 
 urea in the retrograde metamorphosis of tissue. 
 
 (63.) Cynuric acid is a crystalline acid recently discovered Cynuric 
 in small quantity, by Liebig, in the urine of dogs, and which 
 seems to take the place of uric acid. He was only able to 
 obtain it in a comparatively small number of cases. It has 
 not yet been submitted to ultimate analysis. 
 
 (64.) TABULAR VIEW OF THE COMPOSITION OF THE NITROGENOUS 
 
 CONJUGATED ACIDS. 
 
 Hippuric acid, Gtycocholic acid, 
 
 C 18 H 8 N0 5 .HO. C 52 H 42 NO n .HO. 
 
 Carbon . . 60-335 Carbon . . 67-097 
 
 Hydrogen . . 4-469 Hydrogen . . 9*032 
 
 Nitrogen . . 7-821 Nitrogen . . 3-011 
 
 Oxygen . . 22-347 Oxygen . . 18-925 
 
 Water 5-028 Water 1-935 
 
 * Op. cit. 
 F 3 
 
70 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Hyocliolic acid, 
 C 54 H 43 N0 10 . 
 
 Carbon . . 70-28 
 
 Hydrogen . . 9-33 
 
 Nitrogen . . 3-04 
 
 Oxygen . . 17-35 
 
 Inosic add, C 10 H 6 N 2 12 . HO. 
 Carbon . . 32-787 
 Hydrogen . . 3-279 
 Nitrogen . . 15-300 
 Oxygen . v ;. 43-716 
 Water 4-918 
 
 Taurocholic acid, 
 C 52 H 46 NS 2 14 . 
 
 Carbon 
 
 . 60-58 
 
 Hydrogen . 
 
 . 8-74 
 
 Nitrogen *i 
 
 V 2-72 
 
 Sulphur -"-; ' 
 
 tf 6-21 
 
 Oxygen ; 
 
 . 21-75 
 
 Uric acid, C 10 H 4 N 4 6 . 
 Carbon . . 35-72 
 Hydrogen . . , 2*38 
 Nitrogen . v- 33-33 
 Oxygen * ^^28-57 
 
71 
 
 CHAPTER IV. 
 HALOID BASES AND SALTS. 
 
 (65.) THERE are three groups of haloid bases which require Haloid 
 notice from their connection with animal chemistry. 
 
 1. Those represented by the formula C n H n+1 0, and in- 
 cluding 
 
 Oxide of doegling .... C 24 H 25 0, 
 
 Oxide of cetyl C 32 H 33 0, 
 
 Oxide of cerotyl C 54 H 55 0, 
 
 and Oxide of melissyl .... C 60 H 61 0. 
 
 2. Those represented by the formula CnHn^O. The only 
 base of any physiological interest pertaining to this group is 
 the hypothetical oxide of lipyl, C 3 H 2 0. 
 
 3. The members of the group represented by the formula 
 C n H n _ 7 . HO. We are at present only acquainted with 
 
 Hydrated oxide of phenyl . . . C 12 H 5 . HO, 
 and Hydrated oxide of tauryl . , , C U H 7 . HO. 
 
 (66.) The existence of oxide of doegling is still somewhat 
 problematical. Scharling believes that it exists in combina- 
 tion with doeglingic acid in the fat of Balcena rostrata. 
 
 Oxide of cetyl is found only in spermaceti in combination 
 with cetylic acid. 
 
 Oxide of cerotyl, known also as cerotin, occurs chiefly in 
 Chinese wax in combination with cerotic acid. 
 
 Oxide of melissyl, formerly known as myricin, occurs in 
 ordinary wax. 
 
 F 4 
 
72 PHYSIOLOGICAL CHEMISTRY. 
 
 The three last named bodies, in combination with an atom 
 of water, occur as solid, but easily fusible, white, wax-like 
 substances. 
 
 Oxide of (67.) Oxide of lipyl, though a hypothetical body, is of far 
 lipyl> more importance than any of the preceding bases. It is well 
 
 known that if we boil a fat or fatty oil with an alkali and 
 water, the fat is decomposed into one or more fatty acids 
 (which combine with the base that has been employed, form- 
 ing soaps), and a peculiar sweet matter, glycerine. In this 
 process there is no assimilation of oxygen or evolution of 
 hydrogen, but the resulting products exhibit an augmentation 
 of weight from the assimilation of water. 
 
 It was formerly assumed that the fats were combinations 
 of the fatty acids with glycerine, whose formula was supposed 
 to be C 3 H 2 ; but the constitution of glycero-sulphuric acid 
 proves that glycerine must be represented by the formula, 
 C 6 H 7 5 . HO, and that consequently it cannot be regarded as 
 the base of the neutral fats. Hence it is probable that the 
 fats contain, in adition to the fatty acid, the oxide of a radical 
 having the composition which was formerly ascribed to gly- 
 cerine ; and that this oxide, in its separation from the fatty 
 acid, takes up water, and is converted into glycerine. To this 
 hypothetical radical Berzelius gave the name of lipyl. 
 
 Two atoms of oxide of lipyl, taking up four atoms of water, 
 may be supposed to form one atom of glycerine (2C 3 II 2 + 
 4HO = C 6 H 7 5 . HO). According to this theory the fats 
 must be regarded as salts, formed by the union of the fatty 
 acids with the oxide of lipyl. 
 
 Glycerine. (68.) Glycerine is a faintly yellow fluid, with an agreeable 
 sweet taste ; it dissolves readily in water and alcohol, but not 
 in ether, and exerts no action on vegetable colours. 
 
 Glycerine, in the form of glycero-phosphoric acid, or acid 
 phosphate of glycerine (C 6 H 7 5 . 2HO + P0 5 ), has recently 
 been discovered by a French chemist, Grobley, in the yolk of 
 the egg, both in birds and fishes, and in the brain-fat, in com- 
 bination with ammonia. 
 
THE FATS. 73 
 
 There can be no doubt that the origin of the glycerine in 
 the animal body must be referred to the neutral fats ; but 
 since many fatty acids,, either free or in combination with - 
 alkalies, are found in tolerable abundance in the organism, 
 while the fats, which are taken in considerable quantity with 
 the food, are neutral, and therefore yield glycerine, it is 
 obvious that there must be much glycerine to be accounted 
 for, besides the small quantity which exists in combination 
 with phosphoric acid. We know that when glycerine that has 
 been diluted with water is mixed with yeast and exposed to a 
 temperature of 70 or 80 it is converted into metacetonic 
 acid ; it is not impossible that a similar change may occur in 
 the body, the metacetonic acid being burned in the blood as 
 soon as it is formed. 
 
 (69.) The true neutral Fats or Salts of oxide of lipyl now The Fats. 
 claim our consideration. The properties of thes*e fats are ex- 
 tremely similar to those of the fatty acids already described. 
 Most animal fats are soft and greasy at an ordinary tempera- 
 ture, although some are firm and waxy, and a few liquid. They 
 are insoluble in water, but most of them dissolve in boiling 
 alcohol, from which they again separate on cooling, and all of 
 them are freely soluble in ether and in volatile oils. They 
 are colourless or yellowish, devoid of taste and odour (when 
 fresh), float on water, render paper or linen transparent, fuse 
 below the boiling point of water, and solidify, when their 
 alcoholic solutions are exposed to great cold, in white nacreous 
 scales or plates. On exposure to the air they absorb oxygen, 
 evolve volatile acids, and become rancid. They are inflammable, 
 and burn with a bright flame. When strongly heated they 
 evolve the pungent odour of acrolein from the decomposition 
 of their base. 
 
 Albuminous substances, in a state of putrefaction, and fresh 
 pancreatic juice, act as ferments, and resolve the fat into 
 glycerine and the corresponding fatty acid, in the same manner 
 as sugar is resolved by yeast into alcohol and carbonic acid. 
 
74 PHYSIOLOGICAL CHEMISTKY. 
 
 (70.) The fats occurring in the animal body are usually 
 mixtures of various compounds of fatty acids with oxide of 
 lipjl- Thus, human fat, according- to the recent investiga- 
 tions of Heintz *, is a mixture of the stearate, palmitate, and 
 oleate of oxide of lipyl ; while, according to the former and 
 more generally received view, it consists of margarate and 
 oleate of oxide of lipyl ; the solid fat of herbivorous animals 
 consists of a mixture of various salts, in which the stearates 
 very much preponderate ; while butter contains oxide of lipyl 
 in combination not only with margaric and oleic acids, but 
 with an extensive group of volatile fatty acids (see 246. in the 
 chapter on The Milk "). 
 
 (71.) The following are the most common of the oxide-of- 
 lipyl compounds : 
 
 Stearate of oxide of lipyl, or Stearin, occurs as a white mass. 
 It separates from a hot alcoholic solution, on c'ooling, in 
 glistening scales, which, when seen under the microscope, are 
 chiefly found to be nearly perfect squares (being rhombs, with 
 
 * Heintz has been for many years actively engaged in the examination of 
 the fats, and has thrown their chemistry into a sad state of confusion. In 
 a Memoir " On the Composition of Human Fat," published in vol. Ixxxiv. 
 of Poggendorff's " Annalen," and translated in an abridged form in the fifth 
 volume of the " Quarterly Journal of the Chemical Society," he maintains 
 that human fat is a mixture of at least six different fats ; namely, stearo- 
 phanin (a fat discovered by Francis in the berries of cocculus indicus) ; an- 
 thropin (a new substance, whose acid is represented by the formula C 34 H 32 O 4 ); 
 margarin; palmitin (which is more abundant than any of the preceding ones); 
 olein ; and another fat (to which he does' not assign a name), which coexists 
 with olein in the liquid portion of the fat, but which on saponification yields 
 an acid whose baryta-salt differs essentially from oleate of baryta. 
 
 In a subsequent memoir in vol. Ixxxvii. of Pogg. Ann. we find these views 
 materially modified ; for there we find him holding : 
 
 1. That his anlhropic acid is only a mixture of about seven parts of palmitic 
 acid with five of stearic acid. 
 
 2. That margaric acid is only a mixture of about ten parts of palmitic acid 
 with one part of stearic acid ; and 
 
 3. That the solid part of human fat consists solely of two fats, namely, of 
 stearin and palmitin, in which the latter strongly predominates. See his 
 " Zoochemie," pp. 383-523, and 1067-1080. 
 
THE FATS. 75 
 
 angles of 90 5') ; sometimes, however, short rhombic prisms 
 (thick rhombic plates) are observed. (Plate IV. fig. 1.) It 
 fuses at 1436. On saponification it yields glycerine and 
 stearic acid. 
 
 (72.) Mar gar ate of oxide of lipyl, or Margarin, is less solid Margario. 
 than stearin, and crystallises from hot alcohol as a white 
 flocculent powder, which, under the microscope, appears in 
 the form of very delicate needles, which are so grouped as 
 to radiate from one point, and thus to form a whorl of fine 
 capillary threads. (See Plate IV. fig. 2.) It fuses at 1 184. On 
 saponification it yields glycerine and margaric acid. 
 
 (73.) Oleate of oxide of lipyl, or Olein, is a colourless oil, Olcin. 
 which remains fluid at as low a temperature as 24, becomes 
 rancid on exposure to the air, is never entirely free from mar- 
 garin and stearin, but yields on saponification, in addition to 
 glycerine and oleic acid, a much larger quantity of margaric 
 acid than can be supposed to be derived from the decomposi- 
 tion of the margarin. 
 
 In the detection of free (that is to say, non-saponified) fats 
 the microscope is of more service than any chemical test. 
 When seen under a moderate power the fat appears in drops 
 or globules, or in true fat-cells which may be of a spherical, or 
 oval, or a polyhedric form. These fat-cells occur in varying 
 quantities in the connective tissue, forming the base of the 
 corium and surrounding the muscles, being most abundantly 
 found under the skin of the palm of the hand and the sole 
 of the foot, and between the different glutaeal muscles. The 
 globules of free fat are shown in Plate I V. fig. 3., and present 
 so characteristic an appearance that when they have been 
 seen a few times they can hardly be confounded with anything 
 else. 
 
 (74.) Fats occur both in the animal and the vegetable Occurrence 
 kingdoms ; they are found in almost all parts of most animals, 
 it being only in the lowest classes that fat is entirely absent. 
 
 In connection with the human body (and the same remarks 
 
76 PHYSIOLOGICAL CHEMISTRY. 
 
 apply to most mammals) we find a special fatty tissue (the 
 cellular tissue of the older writers) immediately beneath the 
 skin, in which the fat occurs in the above-mentioned cells. 
 There are some organs, as, for instance, the orbit and the in- 
 tervals between the muscles of the face, in which the fatty 
 tissue must be regarded as a necessary and integral con- 
 stituent, inasmuch as it does not disappear even in the latest 
 stages of wasting diseases. The largest quantities of fat are 
 found in the omentum, around the kidneys, and in the female 
 breasts ; while the smallest quantity, and occasionally not a 
 trace, of fat is to be found in the pulmonary tissue, the glans 
 penis, and the clitoris, and, if we except the so-called non- 
 saponifiable fats, in the brain. 
 
 The marrow of the bones consists almost solely of fat rich 
 in olein. 
 
 There is scarcely any animal fluid (probably none except 
 the urine) in which larger or smaller quantities of fat cannot 
 be recognised. It is most abundant in the yolk-fluid, where it 
 often amounts to more than 21^-. In pus it usually amounts 
 to 5-g-, and in milk to about 3'5-g-. The chyle also is mode- 
 rately rich in fat, especially after the use of fatty food, when 
 this constituent sometimes rises to 3. In the blood and 
 lymph the fat is for the most part saponified and dissolved, 
 and not in a free, suspended state, as in the preceding fluids. 
 It is only in special conditions that we find free unsaponified 
 fat in suspension in the blood, as, for instance, shortly after the 
 use of fatty food, not unfrequently in cases of pregnancy, but 
 most commonly in drunkards with granular liver. 
 
 The solid excrements sometimes contain a large quantity 
 of free fat ; this is especially observed after the excessive use 
 of fatty foods, particularly if diarrhoea be present, or if, for 
 any reason, the flow of bile into the intestine be impeded. 
 
 Certain organs, as the liver and spleen, and to a less extent 
 the kidneys, always contain more or less fat (either free or en- 
 closed in cells) in their normal state. In morbid conditions, 
 
ORIGIN OF FAT. 77 
 
 especially in the state of fatty degeneration, the fat accumu- 
 lates in large quantities in these organs. We likewise meet 
 with pathological deposits of fat in paralysed muscles, in the 
 heart (in fatty degeneration), and in encysted tumours, lipoma, 
 &c. The formation of fat is in these cases apparently due to a 
 retrograde metamorphosis of the protein-compounds. 
 
 The quantity of fat in the human body varies considerably 
 at different periods of life. In the earlier periods of foetal 
 existence we find scarcely any fat ; in new-born children there 
 is usually a considerable quantity of this substance deposited 
 under the skin ; and the organism continues rich in fat during 
 childhood. It diminishes with the development of the sexual 
 functions, although it again increases about middle life, and 
 then occasionally acquires an excess never observed at any 
 other age. In extreme old age the fat is sometimes almost 
 completely absorbed. The female organism generally con- 
 tains more fat and exhibits a greater tendency to fatty 
 depositions than the male. The influences exerted by ex- 
 cessive activity of the sexual functions, by great muscular 
 exercise, by food, temperament, &c. on the amount of fat, are 
 too well known to require special notice. 
 
 (75.) The origin of the fat in the animal body must, Its origin, 
 undoubtedly, be chiefly referred to the fat taken with the 
 food ; it has, however, been established by the most careful 
 statistico-chemical investigations on milch cows, on various 
 animals submitted to the process of fattening, on bees fed 
 with cane-sugar or with honey containing scarcely any wax, 
 and on the insects inhabiting galls*, that the animal, like the 
 vegetable, organism has the power of forming or producing 
 
 * See the observations of MM. Lacaze-Duthiers and Kiche, in the second 
 volume of the fourth series of the " Annales des Sciences Naturelles." They 
 have examined the composition of the galls and of the larvae of the cynips 
 inhabiting them, and have incontestably proved that the fat which abounds in 
 these larvae is produced from the starch which forms the interior of the gall 
 in which the animal lives. 
 
78 PHYSIOLOGICAL CHEMISTRY. 
 
 fat. In these experiments far more fat was found in the 
 
 body of the animal than could be referred to the fat taken 
 with the food, and hence the excess must have been formed 
 either from the carbo-hydrates (sugar, starch, &c.), or from the 
 nitrogenous protein-bodies (fibrin, albumen, &c.) which had 
 been consumed. We shall postpone the consideration of the 
 arguments that may be advanced in favour of these two views 
 till we treat of the metamorphosis of tissue generally; and 
 will at present only remark that we are still entirely ignorant 
 of the process by which fat is produced from either of these 
 sources, and of the exact seat of its formation. 
 
 Uses of fat. (76.) The physiological value of the fats is due partly to 
 their physical and partly to their chemical characters. 
 
 The uses of the fat deposited in the subcutaneous areolar 
 or connective tissue are almost entirely of a physical nature; 
 by causing a uniform diffusion of pressure through the whole 
 adipose tissue it protects the body from blows or other 
 external shocks. The body is further guarded from injury in 
 leaping and falling by the fatty masses which penetrate the 
 joints and are known as the Haversian glands ; and the layers 
 of fat on the soles of the feet and on the tuberosities of the 
 ischia have a similar object. 
 
 Another physical use of fat is to promote the mobility of 
 the muscles and other organs. Hence fat is found to remain 
 the longest in the parts where motion is most needed, as in 
 the heart, the orbit of the eye, and in the abdominal cavity. 
 
 Another important physical property of fat is that of ren- 
 dering other bodies supple and diminishing their brittleness. 
 In this point of view the utility of fat is very conspicuous in 
 the bones. 
 
 Fat is, moreover, a very bad conductor of heat, and hence 
 the layer of this substance beneath the skin materially checks 
 the loss of free heat by radiation. This use of fat is most 
 clearly seen by a reference to some of the lower animals 
 which are exposed to a very low temperature. In the common 
 
USES OF FAT. 79 
 
 seal the whole of the fat is collected in the subcutaneous 
 areolar tissue, where it forms a layer of nearly half an inch 
 in thickness, and a similar arrangement is observed in the 
 cetacea. 
 
 The first of the chemical uses of the fat to which we shall 
 advert is its power of exciting and supporting the animal 
 heat. In the oxidation of the fats in the animal organism, 
 whether the process be gradual or rapid, a large amount of 
 heat must of necessity be liberated ; and that they are 
 oxidised and, for the most part, ultimately reduced to car- 
 bonic acid and water, is evident, because they neither appear 
 in any quantity in the excretions nor accumulate beyond a 
 certain point in the organism. 
 
 Fat is one of the most active agents in the metamorphosis 
 of animal matter. Lehmann ascertained, in experiments on 
 lactic fermentation, that the process cannot be excited in 
 saccharine or amylaceous fluids by albuminous bodies, ex- 
 cepting with the co-operation of fat ; he likewise found that 
 a certain, although a small, quantity of fat was indispensable 
 to the metamorphosis and solution of nitrogenous food during 
 gastric digestion a fact which has received confirmation 
 from the observation that, in experiments on artificial diges- 
 tion, the solution of substances used as food is considerably 
 accelerated by the presence of a little fat. The occurrence of 
 fat in the egg, in pus, in all plastic exudations, and in all 
 highly cellular organs, is a clear indication that this substance 
 plays an important part in the process of cell-formation ; and 
 no animal cell or cell-yielding plasma has ever been observed 
 into which fat does not enter as a constituent. 
 
 Lastly, a portion of the fat which is taken with the food 
 is applied to the formation of the bile. The chemical argu- 
 ments in favour of the view that the resinous acid of the bile, 
 cholic acid, is formed from fat, are already given in 28, in 
 our remarks on the origin of that acid. Various physiolo- 
 gical facts may also be adduced in support of this opinion. 
 
80 PHYSIOLOQICAL CHEMISTRY. 
 
 Thus, when animals are starved for any length of time, the 
 gall-bladder is found to be perfectly full, and there is a free 
 discharge of bile from the liver. Under these circumstances, 
 from whence can the liver draw the carbonaceous materials 
 from which the bile is formed, unless from the fat, which 
 disappears with great rapidity ? Indeed, it has been clearly 
 demonstrated, by the experiments of Bidder and Schmidt*, 
 that, in animals which are being starved, the amount of bile, 
 secreted daily, diminishes in nearly the same proportion in 
 which the fat of the body disappears. They likewise found, by 
 corresponding observations on similar animals, with and with- 
 out artificial biliary fistulse, that the former animals, in whom 
 the bile escaped externally, and, therefore, did not again enter 
 the circulation to be consumed there, constantly evolved less 
 carbon from the lungs (in the form of carbonic acid) than the 
 latter; and they further demonstrated, by a comparison of 
 the inspired oxygen with the expired carbonic acid, that the 
 missing carbon actually pertained to the fat, and to no other 
 substance. These and other similar observations suffice to 
 establish the fact, that the fats contribute essentially to the 
 formation of bile ; and, were it necessary, numerous patho- 
 logical phenomena might be adduced as corroborative evidence. 
 (77.) From the consideration of the oxide of lipyl and its 
 salts we proceed to that of the third group, which presents 
 scarcely any basic properties ; indeed, the members of it have, 
 till very recently, been classed amongst the acids, and termed 
 the phenylic-acid group. 
 
 Phenylic Hydrated oxide of phenyl, known also both as phenylic and 
 
 carbolic acid, is a colourless, transparent, oily liquid, with a 
 burning taste and the odour of creosote, to which it bears a 
 great general resemblance. It is slightly soluble in water, 
 but dissolves freely in alcohol and ether, its solutions having 
 no effect on litmus paper. The only reaction that we need 
 
 * Verdauungsafte und_Stoffwechsel, 1852, pp. 386-395. 
 
THE LIPOIDS. 81 
 
 notice is that with the persalts of iron, to which it communi- 
 cates a blue tint, like salicylous and salicylic acids. It was 
 originally obtained as a product of the dry distillation of oil 
 of coal-tar. 
 
 This acid exerts so poisonous an action on the animal 
 organism that, a priori, we should deem its occurrence there 
 highly improbable. Wohler has, however, established the 
 fact of its existence in castoreum in association with benzoic 
 and salicylic acids ; and Stadeler regards it as a normal con- 
 stituent of the urine of the cow : it is, however, most probably 
 only a product of the decomposition of that fluid, formed 
 during his treatment. It has been maintained that it occurs 
 in the urine (in association with salicylous and salicylic acids) 
 after the ingestion of salicine; but although it is doubtless 
 yielded in considerable quantity by the distillation of that 
 fluid, it has been established, by the investigations of Eanke, 
 that it does not exist there in a preformed state. If the 
 observations of Fetters (of whose skill as a chemist I know 
 nothing) are to be relied on, inunction with tar ointment 
 seems to occasion the presence of carbolic acid in the urine.* 
 
 Hydrated oxide of tauryl, or taurylic acid, closely resembles Taurylic 
 the preceding substance in its general chemical characters ; 
 and, like it, it has been found by Stadeler amongst the pro- 
 ducts of distillation of cows' urine. 
 
 LIPOID& 
 
 (78.) This term is now applied to those bodies which were Lipoids 
 formerly called non-saponifiable fats. In many of their phy- 
 sical characters they resemble the true fats or salts of oxide 
 of lipyl, but they differ essentially from them in their chemical 
 composition and in the products of their decomposition. 
 
 * An abstract of his Memoir may be seen in Schmidt's Jahrbiicher, 1855, 
 vol. Ixxxviii. p. 158. 
 
 a 
 
82 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Its occur- 
 rence. 
 
 The bodies pertaining to this class are : - - 
 
 Cholesterin .... C 28 H 24 O 
 Castorin ? 
 
 Ambrein . . . ? 
 
 Serolin . . . ' ^ ? 
 
 (79.) Cholesterin separates from an alcoholic solution in white, 
 nacreous scales, which, under the microscope, are seen to be 
 very thin and almost transparent rhombic tablets, whose angles 
 are 100 30' and 79 30' respectively. In many of the tablets 
 the edges and angles are more or less irregular. It is devoid 
 of taste and smell, is perfectly neutral, fuses at 293, is per- 
 fectly insoluble in water, but dissolves in boiling alcohol from 
 which it crystallises on cooling, in ether, in fatty oils, and to 
 a certain degree in taurocholic acid. 
 
 The microscope affords the best means of testing/or choles- 
 terin ; if by its insolubility in water, acids, and alkalies, and 
 by its solubility in alcohol and ether, it has been ascertained 
 to be a fatty matter, it may be easily distinguished from all 
 other similar substances by a measurement of its angles. The 
 tablets are often so thin that their outline cannot be easily 
 traced, unless we partially shade the field of the microscope. 
 (Plate IV. fig. 3.) When the cholesterin occurs in solution, as 
 in fluids containing oil or bile, it is not always very easy to 
 obtain it in a crystalline form. 
 
 Cholesterin is a normal constituent of the bile, in which it 
 exists, however, in very small quantity. In healthy bile it is 
 held in solution by the taurocholic acid (or taurocholate of 
 soda), but in partially decomposed bile, or (possibly when it 
 occurs in abnormal quantity) we find it deposited in its crys- 
 talline form. It is the main constituent of most biliary 
 calculi. 
 
 It is also a normal constituent of the blood, the quantity 
 in which it occurs varying from 0-0025 to 0'02, the 
 average being 0-0088. The cholesterin increases in the 
 blood in old age and in acute inflammatory diseases. 
 
CHOLESTERIN. 83 
 
 Cholesterin is constantly found in considerable quantity in 
 the brain, spinal chord, and nerves. Lehmann once found 
 the choroid plexus completely encrusted with crystals of 
 cholesterin. 
 
 It appears to be an integral constituent of normal pus, and, 
 when that fluid becomes acid, beautiful tablets of this sub- 
 stance may be observed on a microscopic examination. It 
 has, moreover, been found in large quantity in dropsical 
 exudations, especially in the fluids of ovarian dropsy and of 
 hydrocele ; in exudations, especially in obsolete tubercle, old 
 echinococcus cysts (such as are sometimes found in the liver), 
 and in the ovaries and testes in certain forms of disease. It 
 has likewise been observed on the inner coat of arteries that 
 have undergone atheromatous degeneration, in various kinds 
 of tumours, and in the crystalline lens in cases of cataract. 
 
 The cholesterin which is often found in the solid excre- 
 ments takes its origin in the bile. It occurs abundantly in 
 the meconium. Traces of it have been found in urine. 
 
 Nothing is known regarding the origin of cholesterin ; but, its origin, 
 from the positions in which it occurs, we may conclude that 
 it is a product of excretion. Much as it resembles the fats in 
 its physical and some of its chemical characters, we cannot 
 suppose that it is derived from them, since the fats are 
 oxidised in the animal body, whereas to form cholesterin 
 they must undergo a process of deoxidation. 
 
 (80.) Castorin and ambrein are crystallisable lipoids occur- Castorin 
 ring in castoreum and amber respectively. Their chemical ^^ m 
 constitution is not accurately known, and they are of little 
 physiological importance. 
 
 (81.) Serolin, which was discovered by Boudet in the solid Serolin. 
 residue of the serum of the blood, appears, from the researches 
 of Grobley*, to be nothing more than a mixture of the crystal- 
 lisable fats contained in that fluid, with a little albumen. 
 
 * Journ. de Chira. Med. 1851. p. 579. 
 G 2 
 
84 PHYSIOLOGICAL CHEMISTRY 
 
 CHAPTER V. 
 
 THE CARBOHYDRATES. 
 
 The carbo (82.") THE substances belonging to this class have received 
 hydrates. 
 
 the name of carbo-hydrates, because, in addition to carbon, 
 
 they contain hydrogen and oxygen in the same ratio as these 
 elements are contained in water; moreover, the number of 
 atoms of carbon in them appears to follow a general law, 
 since, in all the formulae which as yet have been well esta- 
 blished, it is divisible by 6. 
 
 Various as are the physiological properties of these bodies, 
 they closely resemble one another in their products of decom- 
 position as well as in other chemical points of view. They are 
 neutral, have very little tendency to enter into combination 
 with other bodies, and, in the few cases in which they do so, they 
 combine in several proportions, so that it is difficult to deter- 
 mine their atomic weights with certainty. They are all decom- 
 posed by heat, yielding acid volatile products and inflammable 
 gases, in addition to aqueous vapour. By digestion with dilute 
 mineral acids most of them are converted into grape-sugar. 
 These bodies arrange themselves into four well-known natural 
 groups, the sugars, gums, starches, and woody bre or cellu- 
 lose ; but, in relation to zoo-chemistry, we need only notice 
 the following individual members of these groups : 
 
 Grape-sugar or glycose . . C 12 H 12 12 + 2HO 
 
 Milk-sugar C 12 H 12 12 
 
 Inosite or muscle-sugar . . C 12 H 12 12 + 4HO 
 
 Paramylon C 12 H 10 10 
 
 Cellulose ..... C 12 H 10 10 
 
SUGAR 85 
 
 (83.) Grape-sugar ', known also as glucose (which ought to Grape- 
 be written glycose) and diabetic sugar, crystallises with 2 giy^ose?* 
 atoms of water in wart-like masses, consisting of minute 
 rhombic plates, arranged in a cauliflower form. It is white, 
 devoid of odour, and not so sweet as cane-sugar, but sweeter 
 than milk-sugar. It dissolves in 1*5 times its weight of cold 
 and far more readily in hot water ; it is also soluble in spirit, 
 and to a lesser extent in absolute alcohol, but is insoluble in 
 ether. It is directly fermentable; that is to say, in the 
 presence of yeast, and at a mean temperature, it undergoes 
 direct conversion into alcohol and carbonic acid (C 12 H 12 12 = 
 2C 4 H 6 . HO + 4C0 2 ). In contact with nitrogenous bodies, 
 and especially with casein, it undergoes the lactic and sub- 
 sequently the butyric fermentation. Its aqueous solution 
 turns the plane of polarisation of a ray of light to the right.* 
 Like cane-sugar it forms compounds with potash, lime, and 
 oxide of lead, to which the term saccharates | has been ap- 
 plied ; it likewise forms a very beautiful crystalline compound 
 with chloride of sodium. 
 
 The behaviour of this variety of sugar towards different 
 reagents has been very fully studied. We shall here only 
 notice a few of those reactions on which the most trustworthy 
 tests are based. 
 
 (84.) If a solution of glycose be treated with a little solu- Trommer's 
 tion of potash, and a few drops of a solution of sulphate of 
 oxide of copper be then added, there is either no precipitate, 
 or, if one be formed, it redissolves, leaving a beautiful blue 
 fluid : on warming this fluid it assumes an orange colour, be- 
 comes turbid, and finally deposits a yellowish red precipitate 
 of suboxide of copper. This is Trommer's test. When the 
 
 * In the following pages I have not referred to the polarisation test, because 
 the expense of the apparatus excludes it from general use. 
 
 f A very bad term, since there is a saccharic acid formed by the action of 
 dilute nitric acid on sugar. Potash-sugar, lime-sugar, &c., are terms more in 
 accordance with our present rules of nomenclature. 
 
 G 3 
 
86 PHYSIOLOGICAL CHEMISTRY. 
 
 sugar is present in only very small quantity, it is advisable to 
 evaporate the fluid to dryness, to extract the solid residue 
 with alcohol, to dissolve this extract in water, and then to 
 apply the potash and sulphate of copper to this solution. By 
 this course we usually obtain the reaction in its most distinct 
 manner. If there is any probability that albuminate of soda 
 be present, we must neutralise the fluid, previous to its 
 evaporation, with a few drops of dilute acetic acid, which will 
 prevent any albuminous body from being taken up by the 
 alcohol. If the reaction do not fully manifest itself in the 
 alcoholic extract thus obtained, we may precipitate the sugar 
 from the alcoholic solution by an alcoholic solution of potash, 
 dissolve the compound of sugar and potash (the so-called 
 saccharate of potash, or potash-sugar, which occurs in white 
 viscid flakes) in water, and now apply the sulphate of copper. 
 In this way an extremely minute trace of sugar may be beau- 
 tifully exhibited. 
 
 The following precautions should be attended to in the 
 application of Trommer's test: (1.) If the potash gives rise 
 to a copious precipitate, the solution should be filtered before 
 the addition of the sulphate of copper. (2.) The sulphate of 
 copper must be added gradually and in a dilute state, because 
 the quantity of oxide of copper that can be dissolved is pro- 
 portional to the amount of sugar which is present. (3.) Pro- 
 longed heating must be avoided, for there are several animal 
 matters (amongst which we may name the albuminous bodies) 
 which by very prolonged boiling separate a little suboxide of 
 copper from alkaline solutions of oxide of copper. Indeed, 
 when sugar is present, a red or yellow powder of suboxide of 
 copper is usually formed, even without the application of 
 heat, if the blue solution be allowed to stand for some time. 
 
 With .due attention to the above precautions, this is the 
 most trustworthy test for sugar that we possess. 
 
 85. On boiling a fluid containing grape-sugar with a solu- 
 tion of potash, the mixture gradually assumes a brownish red 
 
SUGAR. 87 
 
 or bistre tint, and on then adding a drop or two of nitric 
 acid a pungent odour, somewhat resembling that of burnt 
 sugar, is developed. This reaction, which has been long 
 known in so far as the change of colour is concerned, is some- 
 times designated as Moore's test ; the discovery of the peculiar 
 odour that is evolved on the addition of nitric acid is due to 
 Heller. 
 
 (86.) A test which is very delicate, but which unfortunately Mau ; t 
 applies equally to all the carbo-hydrates, has been recently test, 
 proposed by Maumene. If a pure woollen tissue (merino, for 
 instance) which has been saturated with a solution of chloride 
 of tin and dried, be moistened with a solution of sugar and 
 exposed to a temperature of 212, a glistening black spot will 
 be produced at the point touched by the saccharine solution. 
 
 (87.) The products of the fermentation of sugar serve as a Fermenta- 
 tion test, 
 test for its recognition ; if we wish to determine its amount, 
 
 the carbonic acid that is evolved must be collected in a gra- 
 duated jar over mercury.* When no yeast has been added, the 
 formation of the Torula cerevisice (see PL V.fig. 1.) affords 
 a characteristic indication of vinous fermentation : it must, 
 however, be remembered that very similar cellular formations 
 sometimes present themselves in normal urine that has stood 
 for some time (especially in the summer), and hence the 
 presence of this fungus in urine must not be hastily accepted 
 as a proof that it is diabetic. 
 
 (88.) Sugar (and in the following pages we shall use the Its occur- 
 simple term sugar in place of glycose or grape-sugar) is a 
 substance of very considerable physiological importance. We 
 shall, therefore, notice somewhat fully the different positions 
 in which it has been found. 
 
 Sugar is always found in the primes vice, especially in the 
 small intestine after the use of saccharine or amylaceous food. 
 
 * The yeast employed for the excitement of the fermentation should always 
 be well washed, as it is apt to contain saccharine matter. 
 
 o 4 
 
88 PHYSIOLOGICAL CHEMISTRY. 
 
 Its quantity, however, is generally small, partly because the 
 conversion of starch into sugar is effected slowly, and partly 
 because the sugar is absorbed almost as soon as it is formed. 
 
 It may be detected in small quantity in the chyle during 
 the digestion of amylaceous food.* 
 
 Until recently it was believed that sugar did not exist in 
 normal blood. Although Magendief detected it in con- 
 siderable quantity (in association with dextrine) in the blood 
 of a dog that had been fed for several days upon boiled 
 potatoes, it is to C. Schmidt J that we are indebted for the 
 discovery of the fact that sugar is a normal constituent of the 
 blood of the ox, the dog, the cat, and man. It was very soon 
 afterwards discovered (almost simultaneously by Lehmann and 
 Bernard) that while the portal blood contains no sugar, or at 
 most a mere trace, (which is the more surprising since sugar 
 is abundantly found in the intestine and absorbed by the 
 veins,) the blood of the hepatic veins is rich in that con- 
 stituent. It has been distinctly found by von Becker that 
 highly saccharine food exerts an influence on the amount of 
 sugar in the blood. Thus, for instance, he found that the 
 blood of rabbits which had been fed on carrots yielded 0*336^ 
 of sugar, while there was only 0*148^ in the blood of those 
 animals when fed upon oats, and only 0*097^ in their blood 
 
 * According to Bernard, the lacteals cannot take up sugar from the intes- 
 tinal walls, this being solely effected by the blood-vessels. Hence, as a general 
 rule, the chyle cannot contain this substance. The only point at which it can 
 be detected is just before the duct opens into the subclavian vein, when it has re- 
 ceived the contents of the lymphatics of the liver, which are always saccharine, 
 both in herbivorous and carnivorous animals. See his "Le9ons de Physiologic," 
 &c., 1855, pp. 311314. 
 
 f Compt. rend. vol. xxx. p. 191. 
 
 I Charakteristik der Cholera, 1850. pp. 161163. 
 
 Schmidt ascertained the quantity of sugar by the carbonic acid yielded on 
 fermentation. In two experiments on ox -blood, the quantities were 0'00069 
 and 0-00074g ; in the blood of a dog it amounted to 0*0015, and in that of a 
 cat to 0-002 1. The blood of two healthy men, one cholera patient, two per- 
 sons with dropsy, and one with pleurisy, in all cases gave indications of the 
 presence of more or less sugar. 
 
SUGAR 89 
 
 / 
 
 when they had fasted twenty-six hours. Further details on 
 this subject are given in the chapter on " The Blood." 
 
 In healthy urine we find no sugar ; it only occurs in this 
 fluid under normal relations when very large quantities of sugar 
 have been swallowed at once or in short intervals. It appears, 
 from the experiments of von Becker, that (in rabbits) sugar 
 cannot be detected in the urine unless the blood contain 
 about 0*5^- of that substance ; if less be present, it appears to 
 be consumed in the circulating fluid. 
 
 In diabetes mellitus a very considerable quantity of sugar 
 is daily discharged with the urine. It is occasionally found 
 in the urine in other diseases, as gout, carbuncle, &c. 
 
 Bernard has shown that artificial diabetes may be induced 
 by puncturing the floor of the fourth ventricle, sugar appear- 
 ing in the urine for several hours after the operation. 
 
 The same physiologist* has found sugar in considerable 
 quantity in the foetal urine and in the fluid contents of the 
 amnion and allantois, during the earlier period of intra-uterine 
 life, in the cow and the sheep ; it disappears, however, shortly 
 before birth, when these fluids become thick and viscid 
 Dr. W. D. Moore f has sought, unsuccessfully, for sugar in the 
 urine of the human foetus; as;, however, the specimens of 
 urine which he examined were apparently those of the 
 mature foetus, his failure does not invalidate Bernard's state- 
 ment. 
 
 Sugar in small quantity is invariably found both in the 
 white and in the yolk of eggs; and the amount seems to 
 increase during incubation. 
 
 Sugar is always J found in the tissue of the liver, even 
 
 * Compt. rend. vol. xxx. p. 317. See also his "Le9ons de Physiologic Ex- 
 perimentale," 1855, p. 393. 
 
 f Experiments as to the Existence of Sugar in the Urine of the Foetus. 
 Reprinted from the "Dublin Medical Journal" for 1855. 
 
 J Bernard gives a long list of the mammals, birds, reptiles, fishes (both 
 osseous and cartilaginous), molluscs, and articulate animals, in whose liver 
 he has found sugar, in his "Le9ons de Physiologic Experimentalc," 1855, 
 pp. 62, 63. 
 
90 PHYSIOLOGICAL CHEMISTEY. 
 
 when no amylaceous or saccharine food has been taken, as 
 in the case of carnivorous animals. The amount of sugar in 
 the liver of man, mammals, and birds is much more con- 
 siderable than in that of reptiles, fishes, and molluscs, being 
 about 1'5 or 2-g- in the former classes, and never more than 
 1 in the latter. In slow wasting diseases, as, for instance, 
 phthisis pulmonalis, the liver is often found to contain no 
 sugar. It appears, from Bernard's researches, that it is not 
 until about the middle of intra-uterine life that the liver 
 contains sugar; previously to that time the muscles (both 
 voluntary and involuntary) and the pulmonary tissue contain 
 it, and it gradually disappears from them as it appears in the 
 liver. 
 
 In diabetes sugar occurs in all the serous fluids, in the 
 saliva, in vomited matters, in the solid excrements, and 
 sometimes (but rarely) in the sweat. Bernard mentions the 
 brain, spinal cord, pancreas, and spleen as the only organs 
 in which he failed to detect sugar, in a case of diabetes which 
 he carefully examined during and after death. 
 
 (89.) The sugar which is found in the organism originates 
 from two distinct sources. 1. The amylaceous matters of 
 the food are converted into sugar by the saliva, pancreatic 
 fluid, and intestinal juice. 2. Sugar is formed in the liver, 
 most probably from nitrogenous matters - a view which is 
 supported, in the first place, by the abundance in which 
 sugar exists in that structure ; secondly, by the fact that the 
 portal blood flowing to the liver is extremely poor in sugar, 
 while the blood of the hepatic veins proceeding from the 
 liver is richer in sugar than the blood of any other vessels ; 
 and, thirdly, by a beautiful chemical experiment of Leh- 
 mann's*, who has obtained from pure hsematin (a nitro- 
 genous substance) a saccharine body which reduces oxide 
 of copper, and with yeast resolves itself into carbonic acid and 
 alcohol. 
 
 * Bernard's " Le9ons," &c. 1855, p. 390. 
 
SUGAR OF MILK, 91 
 
 Since the publication of his " L^ons," Bernard has been 
 led to believe that the sugar is actually formed from the 
 tissue of the liver itself, and not from the blood.* 
 
 The physiological importance of sugar will be fully noticed 
 in the chapter on " The Metamorphosis of Tissue." 
 
 (90.) Sugar of milk crystallises in white, glistening, four- Sugar ot 
 sided prisms with pointed ends, is hard, craunches between 
 the teeth, and is less sweet and less soluble than the other 
 varieties of sugar. It behaves with sulphate of copper and 
 potash in the same manner as glycose. It may be distin- 
 guished from glycose, which is the only substance with which 
 it is likely to be confounded, by its crystalline form, by its 
 almost entire insolubility in absolute alcohol, and by the 
 difficulty with which it can be made to ferment. (It seems 
 to be incapable of undergoing fermentation till it has been 
 converted into grape-sugar.) 
 
 This substance appears to be an integral constituent of the Its occur- 
 milk of all animals ; it is, however, far less abundant in the 
 milk of carnivorous than in that of herbivorous animals. The 
 quantities in which it occurs in the milk of different animals 
 are given in the chapter on " The Milk." There is no very 
 certain evidence of its existence in any fluid except milk : 
 Gruillot and Leblanc believe, however, that they have de- 
 tected it in the blood of milch -cows; and, in a few cases, 
 it has been supposed to have been found in the urine of 
 women shortly after delivery, f 
 
 As the milk is the only fluid in which this substance has as 
 yet been found as a regular and normal constituent, we are 
 
 * See my review of his book in the " British and Foreign Medico-Chirur- 
 gical Review," 1857, vol. xix. p. 41. 
 
 f The most satisfactory case is that recorded by Bernard in his " Leons," 
 &c., p. 427. Sugar, which was apparently glycose from the readiness with 
 which it entered into fermentation, has also been once noticed under similar 
 circumstances by Lehmann. M. Blot, in a memoir published since the 
 above paragraph was written, maintains that sugar invariably occurs in the 
 urine in the puerperal state, and during lactation, and in about half the 
 cases of pregnancy. Compt. rend., 1856, vol. xliii. p. 676. 
 
92 PHYSIOLOGICAL CHEMISTRY. 
 
 led to infer that it is formed in the mammary glands from 
 the glycose contained in the blood. 
 
 The use of sugar in the nutrition of the young mammal is 
 noticed in the chapter on " The Metamorphosis of Tissue." 
 
 Inosite. (91.) Inosite, or muscle-sugar, crystallises with four atoms 
 
 of water in colourless, four-sided prisms ; which part with 
 their water at 212, have a sweet taste, dissolve readily in 
 water, slightly in strong spirit, and are insoluble in absolute 
 alcohol and ether. It does not reduce oxide of copper, nor is 
 it capable of vinous fermentation; but in the presence of 
 casein or flesh, it undergoes the lactic and butyric ferment- 
 ation. Scherer, its discoverer, finds that in its anhydrous 
 state it is perfectly isomeric with anhydrous glycose. The 
 following characteristic reaction seems to distinguish it from 
 other sugars and carbo-hydrates. If we evaporate a solution 
 of inosite with a little nitric acid on a platinum spatula al- 
 most to dryness, moisten the residue with ammonia and a 
 little chloride of calcium, and then carefully evaporate to 
 dryness, a vivid rose-red tint is developed even if 1-1 30th of 
 a grain of inosite be present. . 
 
 Its occur- Inosite was originally found in the juice of the muscular 
 tissue of the heart. Solocoff, who has repeated Scherer's 
 mode of procedure, readily obtained it from this source, but 
 could not procure a trace of it from the juice of any other 
 muscle; and Panum, of Copenhagen, arrived at precisely 
 similar results. 
 
 Stadeler and Cloetta, in their recent investigations into the 
 chemistry of the glandular structures, have found it in the 
 lungs, liver, spleen, and kidneys. (From 13 pounds of renal 
 tissue 90 grains of inosite were obtained.) They could not 
 detect it in the normal urine either of man or the cow, but 
 obtained unquestionable evidence of its presence in the urine 
 in a case of Bright's disease. Grorup-Besanez was, how- 
 ever, unable to detect it in his examination of the glandular 
 structures. 
 
CELLULOSE. 93 
 
 Nothing is known of its uses ; Heintz seems to think it not 
 improbable that it may be formed in the process employed for 
 its extraction. 
 
 (92.) Paramylon is a glistening white granular starch-like Paramy- 
 matter, which has been obtained by Gottlieb from the bodies 
 of an infusorium, the Euglena viridis. It is of no general 
 interest. 
 
 Cellulose, in a state of purity forms a spongy mass, in- Cellulose, 
 soluble in water, alcohol, and ether, and in dilute acids and 
 alkalies. It is coloured blue by iodine. 
 
 This substance not only forms the basis of all vegetable 
 cells, but is likewise found in some of the lower animals, as, 
 for instance, in the mantle of Phallusia mammillaris, in 
 the tunics of the simple Ascidians, in the leathery mantle of 
 the Cynthiae, and in the outer tube of the Salpse. Cellulose, 
 or a substance closely allied to it, has recently been found in 
 the brain and spinal cord of man and the higher animals, as 
 well as in certain morbid deposits.* 
 
 (93.) TABULAE YIEW OF THE COMPOSITION OF THE NEUTRAL 
 NON-NITROGENOUS BODIES. 
 
 Glycerine, C 6 H 7 5 . HO. Cholesterin, C 28 H 24 0. 
 
 Carbon. . . 39*130 Carbon . . 84-00 
 
 Hydrogen . . 7'609 Hydrogen . . 12-00 
 
 Oxygen . . 43-478 Oxygen . 4-00 
 Water . . . 9-783 
 
 Glycose, C 12 H 12 12 . 2HO. Milk-sugar, C 12 H 12 12 . 
 
 Carbon. . . 36'73 Carbon . . 46-00 
 
 Hydrogen . . 6-12 Hydrogen . . 6-67 
 
 Oxygen . . 48-98 Oxygen . . 53-33 
 Water . . . 8-17 
 
 * On this subject the reader may be referred to an article hy Dr. Arlidge, 
 " On Cellulose, as an Animal Constituent," in the British and Foreign Medico- 
 Chirurgical Review, 1854, vol. xiv. p. 439. 
 
94 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Animal 
 pigments. 
 
 Hscmatin. 
 
 CHAPTER VI. 
 ANIMAL PIGMENTS OR COLOURING MATTERS, 
 
 (94.) OUR knowledge of these substances is very imperfect 
 and unsatisfactory, and they will, consequently, be discussed 
 in a brief manner. We have no means of classifying them 
 according to their rational or even their empirical formulae, 
 because, with one exception, their formulae have not been 
 determined. For convenience we shall arrange them as 
 follows: "^ 
 
 1. The blood-pigment Hsematin* 
 
 2. The bile-pigment. 
 
 3. The urine-pigment. 
 
 4. Other animal pigments* 
 
 (95.) H&matin, whose formula, as determined by Mulder, 
 is C 44 H 22 N 3 6 Fe, is a dark brown, slightly lustrous matter, 
 devoid of taste and smell, and insoluble in water, alcohol, 
 and ether ; it .dissolves, however, readily in spirit containing 
 sulphuric or hydrochloric acid, forming a brown solution 
 which, on saturation with an alkali, assumes a blood-red 
 colour ; and it is likewise soluble in dilute aqueous solutions 
 of the alkalies and their carbonates. These properties, how- 
 ever, are those of its coagulated (and modified) condition - 
 the only state in which we are acquainted with it, since we 
 have not yet succeeded in separating it in its soluble form 
 from the hsemato-crystallin with which it is associated in 
 the blood-cells. 
 
 It is naturally to be expected that the ratio of the hsematin 
 to the whole mass of the blood should vary with the number 
 
ILEMATIN. 95 
 
 of the blood-corpuscles ; and it is probable that the ratio of 
 this pigment to the haemato-crystallin with which it is com- 
 bined in the blood-cells is also variable ; for the intensity of 
 colour of the individual corpuscles is seen to be very different, 
 when they are viewed through the microscope ; and, if we 
 may take the iron as a measure of the hsematin, equal given 
 weights (say 1000 grains) of hsemato-crystallin or of dried 
 blood-corpuscles usually yield slightly different quantities of 
 iron. 
 
 Nothing is known regarding the origin of the blood- 
 pigment. 
 
 It can hardly be doubted that the hsernatin has a special Its func- 
 function to perform in reference to the corpuscles; but we 
 have no certain knowledge on this point. The facts originally 
 established by Bruch, that blood diluted with water to such 
 an extent that the corpuscles become perfectly invisible and 
 are more or less destroyed, becomes of a brighter red when a 
 current of oxygen is passed through it, and is rendered darker 
 by carbonic acid, seem to indicate that the absorption of 
 oxygen by the blood is due (at least in part) to its chemical 
 action on the hsematin; and Harley's* observations are even 
 more decisive. He took a small quantity of pure hsematin 
 and put it into a vessel along with 1000 volumes of ordinary 
 air. After the air had been kept in contact with the hsematin 
 for some months the gas was found to contain oxygen 16*01 
 (in place of 20-96), carbonic acid 3-80 (in place of 0-002), and 
 nitrogen 80' 19. " The pure colouring principle of the blood, 
 therefore, by exposure to ordinary air, gives off carbonic acid 
 gas, and becomes oxidised in two ways ; first, by a loss of 
 carbon, and, secondly, by direct combination with oxygen." 
 
 Scherer has obtained from the expressed juice of the spleen 
 an albuminous pigment rich in iron, closely allied in its com- 
 position to hgematin ; hence we may infer that the haBmatin 
 
 * Proceedings of the Royal Society, for April 17th, 1856, vol. viii. p. 82. 
 
96 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Haema- 
 toidin. 
 
 Bile-pig- 
 ment. 
 
 Occurrence 
 of bile- 
 pigment. 
 
 (like the blood-corpuscles) undergoes disintegration in this 
 organ. 
 
 (96.) In old extravasations of blood into the connective 
 tissue, or into the parenchyma of an organ, we often find a 
 crystalline substance, usually of a ruby colour; this has 
 received the name of hamatoidin* , and appears to be a modi- 
 fication of haematin. 
 
 (97) Bile-pigment has never been submitted to a thorough 
 chemical examination, partly because we can only obtain it in 
 very small quantity, and partly because it is so unstable that 
 it not only undergoes various modifications in the animal 
 organism, but it is at once changed by the simplest chemical 
 treatment. Hence we cannot give even an empirical formula 
 to represent its composition. In man and the higher mammals 
 it is originally a brown pigment, but it rapidly becomes 
 greenish brown, and finally green, by oxidation. * It is the 
 cholepyrrhin of Berzelius, and the biliphcein of Simon. It 
 may be obtained as a reddish-brown non-crystalline powder, 
 devoid of taste or smell. It is insoluble in water, but dissolves 
 in alkalies and in alcohol. On the addition of nitric acid to 
 the yellowish brown solution of this pigment a green tint is 
 developed, which soon becomes violet, then red ; and, after a 
 considerable period, the red again passes into a yellow : the 
 reaction is best seen when the test contains a little nitrous 
 acid. This brown pigment forms insoluble compounds with 
 the alkaline earths. 
 
 Bile-pigment usually occurs in fresh bile in a state of solu- 
 tion ; but sometimes it is found in the form of granules in a 
 state of suspension. It almost always forms the nucleus and 
 sometimes the whole substance of gall-stones. 
 
 * For a full account of haematoidin, I must refer to Robin and Verdcil's 
 " Traite de Chimie Anatomiqueet Physiologique," 1853, vol. iii. pp. 430437. 
 It has recently been analysed (for the first time) by Robin, who assigns to it 
 the formula C M H 9 N0 3 , and believes that it is formed from hzematin by the 
 abstraction of the iron and of water. See Compt. rend. 1855. vol.xli. p. 506. 
 
BILE-MOMENT. 97 
 
 The bile-pigment which is mixed with the intestinal con- 
 tents rapidly undergoes oxidation, and passes into a yellow 
 pigment. It is in this state that it occurs in the excrements, 
 unless when diarrhoea is present, in which case the unchanged 
 pigment is found. 
 
 Scherer* often detected traces of it in the urine of healthy 
 persons, especially in hot weather. 
 
 In cases of icterus it occurs in the blood, the fluids of the 
 eye, the fluid in the subcutaneous connective tissue, &c., and 
 sometimes even in the saliva and the sweat. In this disease 
 it is constantly found in the urine, which is then coloured 
 brownish red, but becomes green by its own acid fermenta- 
 tion, or by the addition of acids. 
 
 Although we have no certain evidence regarding the origin Its origin, 
 of bile-pigment, there are good reasons for believing that it 
 is formed in the liver from the colouring matter of the blood ; 
 and this view is much strengthened by recent observations, 
 which show that certain crystals, to which Virchow has given 
 the name of bilifulvin, and which are found in bile that has 
 been long retained in the system, are actually convertible into 
 hoematoidin.f Frerichs and Stadeler J have, however, recently 
 (1856) maintained that the bile-pigment is formed from the 
 metamorphosis of the biliary acids. They were first led to Mi is 
 view by the consideration of the fact, established by Lehmann 
 and others, that in those cases in which there is much bil<>- 
 pigment in the urine there are no traces of the biliary acids 
 in that excretion ; while, on the other hand, the biliary acids 
 are often present in considerable quantity when there is little 
 pigment in the urine. Hence they inferred that there must 
 be an intimate relation between the acids and the pigment, 
 and that when the flow of bile was from any cause impeded, 
 the acids either passed unchanged into the urine, or pre- 
 
 * Ann. d. Ch. u. Pharm. vol. Ivii. p. 133. 
 
 f Established by the investigations of Zenkcr and Funke. Sec Lehmann's 
 "Physiological Chemistry," 1854, vol. iii. p. 472. 
 J Muller's Archiv, 1856, pp. 5561. 
 
 II 
 
98 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 viously underwent a change into pigment, either in the blood 
 or some other part of the system. Their chemical experi- 
 ments, which are still in the course of progress, are strongly 
 confirmatory of the accuracy of their views. On treating 
 pure glycocholate and taurocholate of soda with concentrated 
 sulphuric acid, pigments were developed which reacted with 
 nitric acid in precisely the same manner as the bile-pigment. 
 
 We know nothing regarding the uses of the bile-pigment. 
 It may have some special part to play in intestinal digestion, 
 but it is more probably a mere product of excretion. 
 
 (98.) Urine -pigment, like bile-pigment, presents great ob- 
 stacles to a searching chemical investigation, from the small 
 quantity in which it occurs, and from its instability. It pre- 
 sents various modifications, as is obvious from the numerous 
 tints which different specimens of urine (both normal and 
 morbid) present. Scherer has shown that, when the functions 
 of the lungs, skin, and liver are disturbed, the urine-pigment 
 becomes much richer than usual in carbon. Harley has 
 recently succeeded in isolating what he regards as the essen- 
 tial normal urine-pigment. He terms it urohamatin, and 
 feels convinced, from its always containing iron, and on 
 other grounds, that it is modified haematin. 
 
 A brilliant blue pigment, similar to and apparently identical 
 with indigo, is sometimes precipitated from the urine; when 
 dried, it glistens like copper, and it dissolves in alcohol, 
 forming a beautiful blue solution. The colour is sometimes 
 not developed except on the addition of a little hydrochloric 
 or nitric acid. It is in cases of Bright's disease that this 
 pigment is most frequently observed. As neither physiology 
 nor pathology has as yet profited much by these investiga- 
 tions, I deem it sufficient to give, in a foot-note*, the re- 
 
 * Simon's "Animal Chemistry," vol. ii. p. 328 ; Heller "On Uroxanthin, 
 Uroglaucin, and Urrhodin," in his Arch. f. Chem. u. Mikrosk. 1845, p. 161 ; 
 1846, pp. 19 and 536 ; and 1852, p. 121 ; Kletzinsky, on the same subject, in 
 the Arch. f. Chem. u. Mikrosk. 1853, p. 414 ; Scherer, " On the Formation 
 of Indigo in the Human Organism," in the Ann. d. Ch. u. Pharm. 1854, vol. xc. 
 
MELANIN. 99 
 
 ferences to some of the most important memoirs and com- 
 munications on this subject. 
 
 (99.) Of the other animal pigments, the most important is Melanin. 
 melanin, which occurs in hexahedral cells in the choroid coat 
 of the eye. It has been submitted both to qualitative and 
 quantitative analysis by Scherer. Like the other pigments, 
 it is most probably a product of the transformation of 
 hoematin. Its physical importance in the eye is obvious. 
 
 The black pigment, closely resembling melanin, and oc- 
 curring in the bronchial glands, and in the pulmonary tissue 
 of aged persons and of colliers, is not chemically identical 
 with it, as is obvious from the analyses of Schmidt* and of 
 Heintz. f 
 
 Nothing is known regarding the chemical constitution of 
 the colouring matter of the skin in the dark races. 
 
 (99 blS.) TABULAR VIEW OF THE COMPOSITION OF THE ANIMAL 
 
 PIGMENTS. 
 
 Hcematin, H&matin freed from Iron, 
 C 44 H 22 N 3 6 Fe. C 44 H 22 N 3 6 . 
 
 Carbon . . . 65-35 Carbon . . 70-21 
 
 Hydrogen . . 5-44 Hydrogen . . 5-85 
 
 Nitrogen . . 10-40 Nitrogen . . 11-17 
 
 Oxygen . . . 11-88 Oxygen . . . 12-77 
 
 Iron . . . 6-93 
 
 p. 120 ; and Dr. HassalPs Memoir " On the presence of Indigo in Human 
 Urine," in the Proceedings of the Koyal Society, vol. vi. p. 327, and Philo- 
 sophical Transactions for 1854, p. 297. 
 
 For further information on the urine-pigment generally, I may refer to 
 Heintz, op. cit. pp. 804810 ; Kobin and Verdeil, op. cit. vol. iii. pp. 396 
 400 ; and Neubauer and Vogel's " Anleitung zur Analyse des Harns," 2nd ed. 
 1856, pp. 1620. 
 
 * Quoted by Vogel in his " Pathological Anatomy of the Human Body," 
 London, 1847, p. 192. The whole question of the formation of morbid pig- 
 ments is admirably discussed in this volume. 
 
 f Zoochemie, 1853, p. 812. 
 
 it 2 
 
100 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Cholepyrrhin or Biliplia>m, 
 C 32 H 18 N 2 9 
 
 (according to Heintz). 
 
 Brown Urine-pigment 
 
 (Scherer). 
 
 Carbon . . . 60-88 
 
 Carbon , . . 61-37 
 
 Hydrogen . . 6-05 
 Nitrogen . . 9'12 
 Oxygen . '[ ' . 23-95 
 
 Hydrogen . . 6-19 
 Nitrogen . . 7-03 
 Oxygen . . . 25-41 
 
 Pigment of CJioroid Coat 
 (Scherer). 
 
 Pigment from Melanotic Tumour 
 (Heintz). 
 
 Carbon . . . 57-54 
 
 Carbon . . .. 53-44 
 
 Hydrogen . . 5*98 
 Nitrogen . . 13-77 
 Oxygen . . .22-71 
 
 Hydrogen . . 4-02 
 Nitrogen . . 7*10 
 Oxygen . . .35-44 
 
101 
 
 CHAPTER VII. 
 
 THE PROTEIN-BODIES. 
 
 (100.) UNDER this title we include the following substances : Protein- 
 bodies. 
 Albumen. 
 
 Fibrin. 
 
 Syntonin or Muscle-fibrin. 
 
 Casein. 
 
 Grlobulin. 
 
 Hsemato-crystallin. 
 
 Albumen, fibrin, and casein are common both to the 
 animal and vegetable kingdoms. In the present volume 
 these substances are, however, considered solely in reference . 
 to their occurrence in the animal organism. 
 
 These substances differ so slightly from one another in 
 their ultimate composition, in many of their properties, and 
 in the products of their decomposition, that it is not sur- 
 prising that the idea should have suggested itself that they 
 possessed a common radical. 
 
 Mulder believed that he had discovered this radical, which, 
 from its importance, he designated as Protein (from Trpeoreiw, Protein. 
 I hold the first place, or am first) ; while he regarded albumen, 
 fibrin, casein, &c. (which at that period, 1838, were termed 
 albuminous bodies}, as combinations of this protein with sul- 
 phur and phosphorus, or simply with sulphur. According to 
 Mulder, the true composition of protein is (in 100 parts) 
 54'7 of carbon, 6'8 of hydrogen, 14'2 of nitrogen, and 24'3 of 
 oxygen ; and its formula is C 36 H 25 N 4 10 + 2HO. 
 
 Although great doubt has recently been thrown on Mulder's 
 
 H 3 
 
102 PHYSIOLOGICAL CHEMISTRY. 
 
 protein-theory*, we have retained the name of protein-bodies 
 or protein-compounds as being the most convenient for de- 
 signating this group of substances. 
 
 General The protein-bodies may be generally described as nearly 
 
 characters .' 111- -u 
 
 of the pro- colourless, neutral, nitrogenous bodies, soluble in potasn- 
 
 tem-bodies. so j ut i on ^ an( j not yielding gelatin when boiled with water. 
 They all present two .modifications differing essentially from 
 one another, in one of which they are soluble, and in the 
 other nearly or quite insoluble. They exist in the animal 
 organism only in the soluble modification, even when they are 
 not dissolved and cannot be dissolved in water. Most of 
 them are transformed into the insoluble state by boiling, by 
 the mineral acids, and by numerous salts ; one of them, fibrin, 
 undergoes this modification on simple removal from the 
 animal organism. This passage from the soluble into the in- 
 soluble form is termed coagulation, but we do not clearly 
 know what chemical change takes place in the process. " It 
 might be supposed (says Lehmann f ) that coagulation de- 
 pended solely on a rearrangement of the molecules, similar 
 to that which is observed when oxide of tin, titanic acid, &c. 
 assume the insoluble state under the influence of heat ; but 
 direct observations have shown that in the coagulation of the 
 protein-bodies something is removed from them by solution, 
 although this may not amount to more than 2-g- of the original 
 substance : it may be regarded as an established fact that, in 
 the coagulation of albumen, alkali is separated from the soluble 
 modification, while in that of hsemato-crystallin there is a sepa- 
 ration of an acid and salts. Hence we must regard the soluble 
 modifications as compounds which, on heating, lose a proxi- 
 mate constituent, while the remainder (forming the chief 
 mass) becomes insoluble; the latter, however, at the same 
 time loses the power of again uniting itself directly with the 
 
 * See Lehmann's " Physiological Chemistry," voL i. pp. 3289. 
 f Handbuch der Physiologischen Chemie, 1854, p. 74. 
 
THE PROTEIN-BODIES. 103 
 
 separated substance, as is also the case generally with con- 
 jugated substances." 
 
 The soluble protein-bodies in their dried state form pale Properties 
 yellow, transparent, pulverisable masses, devoid of smell or tie protein- 
 taste, which are soluble in water, but insoluble in alcohol and Bodies, 
 ether. They are precipitated from their watery solutions by 
 alcohol, by the mineral acids, and by tannic acid, but not by 
 the other vegetable acids, or by the alkalies : most mineral 
 salts cause precipitates, and the precipitate generally contains 
 combinations both of the acid and of the base with the pro- 
 tein-body. One of their most characteristic properties is, that 
 they are precipitated neither by acetic acid nor by the neutral 
 alkali-salts, but that when the two are simultaneously added, 
 they are thrown down : the precipitate which is thus formed 
 differs in its properties from the original substance, but is 
 soluble in water a fact which shows that it is not reduced 
 to the coagulated form. 
 
 The insoluble protein-bodies, when freshly precipitated, are Of the in- 
 of a white colour, in flakes or small clots, or viscid and glue- protein- 
 like ; when dried they may be reduced to a whitish powder. bodles - 
 They dissolve in concentrated acetic acid, and other organic 
 acids, as well as in the ordinary (tribasic) phosphoric acid, 
 and they are precipitated from these acid solutions both by 
 the yellow and the red prussiate of potash. "With moderately 
 concentrated mineral acids they enter into combinations which 
 present the peculiarity of being insoluble in acidulated water, 
 but soluble in pure water. When heated with concentrated 
 nitric acid they assume an intense lemon-yellow colour; 
 while concentrated hydrochloric acid, with the aid of gentle 
 warmth and prolonged exposure to the air, gradually induces 
 an intense blue tint, and partially dissolves them into a blue 
 fluid. 
 
 The most delicate test for the protein-bodies, whether they Millon's 
 are dissolved in a fluid or simply interspersed in a tissue, is 
 afforded by the application of a solution of mercury, prepared 
 
 H 4 
 
104 PHYSIOLOGICAL CHEMISTRY. 
 
 by dissolving one part of mercury in two of nitric acid of 
 specific gravity 1*41. On the addition of this solution, and on 
 raising the temperature to from 140 to 212, an intense 
 red colour is evolved, which does not disappear either on pro- 
 longed boiling or on exposure to the atmosphere. This is 
 known as Millon's test.* It should be mentioned that it gives 
 a similar reaction with the gelatigenous substances which form 
 the subject of the next chapter. 
 
 In microscopic examinations of the tissues, a solution of 
 iodine, which developes a deep brownish-yellow colour with 
 these bodies, is employed by Histologists. For this purpose, 
 an aqueous solution of iodine with iodide of potassium is 
 employed. 
 
 It has been already mentioned that all the protein-bodies 
 contain sulphur, and some of them phosphorus. Another 
 point worthy of notice is, that they are always accompanied 
 with fats, alkalies, and salts of lime (especially the phosphate, 
 which, according to Mulder, occurs in a definite quantity in 
 albumen, fibrin, and casein, and is doubtless combined with 
 them). 
 
 Their pro- (101.) The products of the decomposition of these bodies, 
 
 decomposi- when acted upon by strong mineral acids, by oxidising agents, 
 
 and by alkalies, have been fully studied by various German 
 
 chemists, amongst whom we may especially mention Schlieper 
 
 and Gruckelberger. 
 
 When digested for a considerable time with strong sul- 
 phuric or hydrochloric acid, they yield leucine, tyrosine, 
 ammonia-salts, and other products that have not yet been 
 fully examined. 
 
 Under the action of oxidising agents, such as chromic acid 
 or black oxide of manganese and sulphuric acid, they yield, 
 as non-nitrogenous products, all the acids of the butyric-acid 
 group and their aldehydes, from formic to caproic acid ; and, 
 
 * Ann. de Chim. et de Phys. 1850, vol. xxix. p. 507. 
 
ALBUMEN. 105 
 
 in addition to these, benzoic acid and hydride of benzoyl (oil 
 of bitter almonds) ; while the principal nitrogenous products 
 are ammonia and hydrocyanic acid. 
 
 When digested for some time with solutions of the caustic 
 fixed alkalies, or when fused with them, there is a develop- 
 ment of ammonia, and of both formic and carbonic acids, 
 while various neutral or basic nitrogenous substances are 
 formed, namely, leucine, tyrosine, glycine, &c. 
 
 These bodies spontaneously undergo the process of putre- 
 faction that is to say, without any apparent cooperation of 
 other matters, and solely by the influence of atmospheric 
 agents. Amongst the products of their putrefaction there are 
 always to be found carbonate, butyrate, and valerianate of 
 ammonia, sulphide of ammonium, leucine, and tyrosine. 
 
 (102.) Albumen, the great type of the protein-bodies, oc- Albumen, 
 curs in very different modifications, which seem to depend 
 on the substances mixed or combined with it ; namely, alka- 
 lies and salts. Hence the albumen of the blood differs in 
 several points of view from that of the egg, and even these 
 kinds of albumen do not present precisely similar reactions in 
 all cases. 
 
 It is doubtful whether the composition of albumen is Its charac- 
 accurately represented by any formula that has yet been 
 calculated. According to Mulder* an equivalent of albumen 
 is represented by the formula 5(Pr + 2HO) + 2SNH 2 ; Pr 
 being = C 36 H 25 N 4 10 (see p. 101), while Lieberkiihn gives the 
 simpler formula C 72 H 56 N 9 22 S.t 
 
 Albumen has few marked characters. In his " Handbuch," 
 Lehmann describes it " as that protein-body whose solution 
 perfectly coagulates at 63 (145'4 F.): it must, however, be 
 recollected that the coagulability is in every point of view a 
 thoroughly relative property; for both the degree of tem- 
 
 * Mulder's " Chem. Untersuchungen," (translated into German by Voelker,) 
 p. 207. 
 f See the Tabular View, at the end of this Chapter. 
 
106 PHYSIOLOGICAL CHEMISTRY. 
 
 perature requisite to induce this change, and the form in 
 which the albumen coagulates, are mainly dependent on the 
 admixture or combination of other substances with it." On 
 the addition of an excess of alkali, or of a free acid which 
 does not precipitate it (as acetic or ordinary phosphoric acid), 
 it ceases to be coagulated by heat, but it is thrown down in 
 the insoluble form on the subsequent neutralisation of the 
 fluid. Albumen coagulates in somewhat different forms, 
 according to the reaction of the fluid in which it is dissolved. 
 Thus, on the evaporation of a very acid or of a very alkaline 
 solution of albumen, a thick, colourless membrane of coagu- 
 lated matter forms upon the surface, which, until recently, 
 was regarded as a certain indication of the presence of casein : 
 from faintly alkaline solutions it either coagulates in a gela- 
 tinous form, or else in such minute particles as to give the 
 fluid a milky appearance ; while from perfectly neutral or 
 faintly acid solutions it coagulates in flakes, which soon sink 
 and leave a clear supernatant fluid. 
 
 The coagulability of a fluid by heat is usually regarded as 
 evidence that it contains albumen ; this, however, is not a 
 sufficient test, since other bodies (shortly to be described) 
 also coagulate when boiled, and, as we have already shown, 
 albumen under some conditions does not coagulate. If the 
 fluid in which we are searching for albumen is either very 
 acid or very alkaline, we must either neutralise it, or treat it 
 with a saturated solution of hydrochlorate of ammonia before 
 heating it. It sometimes happens that on boiling a specimen 
 of urine we obtain a precipitate which closely resembles 
 coagulated albumen, but in reality does not contain a trace 
 of that substance, being composed of earthy phosphates 
 (phosphate of lime and magnesia, and ammoniaco-magnesian 
 phosphate), which, if the fluid be only slightly acid, or 
 neutral, are readily thrown down on boiling : in such cases, 
 however, all doubt may be removed by the addition of a few 
 drops of dilute nitric or hydrochloric acid, which will dissolve 
 
ALBUMEN. 1 07 
 
 the phosphates but will not affect coagulated albumen. As a 
 general rule,, when a fluid coagulates on heating, and is like- 
 wise precipitated by the mineral acids, corrosive sublimate, 
 &c., we entertain no doubt of the presence of albumen : but, 
 strictly speaking, we cannot distinguish albumen in some of 
 its modifications with positive certainty from the similar pro- 
 tein-bodies, especially in the coagulated condition. 
 
 Albumen is always found in the body in a state of solution, Its occur- 
 and generally (if not always) in combination with a small 
 quantity of alkali. (In some experiments made by Lehmann 
 on the albumen of hens' eggs, he found that 1*58 parts of 
 soda were combined with 100 of albumen.) 
 
 Albumen occurs in all those animal fluids which supply the 
 organism with the materials necessary for nutrition and the 
 renovation of effete matters. Hence it is a principal consti- 
 tuent of the blood, lymph, and chyle, of the fluids of the 
 egg, &c. 
 
 It is, moreover, always found in transudations (whether 
 normal or abnormal) from the capillaries, as, for instance, in 
 the fluids in the serous cavities ; and in the parenchymatous 
 fluids of all organs in which active cell-life is going on, as, 
 for instance, the liver, kidneys, brain, and muscles. 
 
 It forms the main solid constituent of the serum of the 
 blood, occurring in the proportion of from 7 '9 to 9'8-g-, and 
 amounting to about 85J of the solid residue. In the blood 
 itself it fluctuates in the normal state between 6'3 and 7'1-g-. 
 
 The secretions, as, for instance, the saliva, gastric juice, 
 bile, and mucus, contain no albumen in their normal state : 
 the pancreatic juice *, however, contains a substance extremely 
 similar to, if not identical with albumen, which coagulates 
 on being heated; and albumen may occur in any of the 
 above-named fluids when their secreting surfaces are inflamed. 
 
 * The albuminous substance of the pancreatic juice has been carefully 
 studied by Bernard. See his Memoir, in the Arch. Gen. de Med. 1848, 4th 
 series, vol. x. p 68. 
 
108 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Albumen has been detected by several observers in the liquor 
 amnii, and is found to be more abundant in that fluid in the 
 earlier than in the more advanced stages of fcetal existence. 
 
 In the normal condition no albumen is contained in the 
 excretions, and its appearance indicates either disease of the 
 excreting organ, or a very abnormal state of the blood. The 
 conditions under which it occurs in the urine and the faeces 
 will be fully noticed when we treat of those substances. 
 
 There can be no doubt that the albumen of the animal 
 fluids is derived from the protein-bodies which enter largely 
 into the composition of most articles of food ; but we are 
 altogether ignorant of the manner in which casein, fibrin, &c., 
 after their conversion in the stomach into peptones* and their 
 subsequent absorption, are further changed into normal 
 albumen. 
 
 The importance of albumen, in connection with the forma- 
 tion and nutrition of the nitrogenous tissues, is sufficiently 
 indicated from the fluids in which it occurs ; and, as will be 
 shown in a future page, this substance requires only very 
 slight modifications to be converted into the contractile struc- 
 ture of which the muscles are composed, or into the contents 
 of the nerve tubes. We do not at present distinctly know the 
 exact manner in which cells and tissues are constructed from 
 albumen ; but there is reason to believe that albumen is, in 
 the first instance, converted into fibrin. 
 
 (103.) Fibrin is distinguished from all the other protein- 
 bodies by its separation in a solid state, in the form of ex- 
 tremely delicate filaments or lamellae, from any fluid in which 
 it is dissolved, very shortly after the abstraction of the latter 
 from the organism. 
 
 Of the properties of dissolved fibrin we know little more 
 
 * Peptones are protein-bodies that have been acted upon and modified by 
 the gastric juice. They differ very much in their physical properties from the 
 protein -bodies, from which they are derived, but they resemble one another 
 very much in their solubility in water, their insolubility in alcohol, and their 
 incapacity of coagulating. 
 
FIBRIN. 109 
 
 than that it is precipitated from its solution by a strong 
 solution of potash (and by ether), but not by acetic acid 
 or ammonia. The spontaneous coagulation of the fibrin in 
 the blood may be greatly retarded by dilute solutions of the 
 alkaline sulphates, nitrates, &c., and may even be entirely 
 prevented by concentrated solutions. 
 
 Spontaneously coagulated fibrin differs in several respects 
 from fibrin that has been coagulated by boiling : it absorbs 
 oxygen and undergoes the process of putrefaction more readily 
 than any other protein-body, and it is further distinguished 
 by the fact that in water, containing Ol of hydrochloric 
 acid, it swells into a jelly-like mass, but does not dissolve like 
 the other protein-bodies, and that when digested with a dilute 
 solution of nitre (1 part of the salt in 17 parts of water) it 
 dissolves into a fluid coagulable by heat. 
 
 Boiled fibrin differs in no essential point from the other 
 coagulated protein-bodies. 
 
 The ultimate analyses of fibrin, made by different chemists, Composi- 
 differ too much to enable us to calculate even an empirical tlon * 
 formula for the composition of this substance. In the fibrin 
 of ox-blood Killing found 1*319, and Verdeil 1*593^ of sulphur, 
 while Mulder found only 1'2-g-; according to the last-named 
 chemist it also contains O3^ of phosphorus. Most recent 
 analyses tend to show that it contains rather more oxygen 
 than albumen. A little fat, consisting chiefly of ammonia and 
 lime in combination with a fatty acid, is always associated with 
 fibrin, and amounts to about 2 '6^- of the dried substance. 
 Like all the protein-bodies, it likewise contains phosphate of 
 lime. 
 
 The ordinary test for fibrin in solution is its spontaneous 
 coagulability. Coagulated fibrin, such as is supposed to occur 
 in exudations, tubercular deposits, &c., cannot, as a general 
 rule, be distinguished from the other coagulated protein- 
 bodies. 
 
 Fibrin occurs principally in the blood, the lymph, and the Its occur- 
 
 r J rence. 
 
 chyle. 
 
110 PHYSIOLOGICAL CHEMISTRY. 
 
 In healthy venous blood it hardly ever reaches 0*3f ; it 
 generally fluctuates between O20 and 0-27-g-. Small as its 
 amount is, it varies in quantity more than any other consti- 
 tuent of the blood, as in some morbid conditions it exceeds 
 its ordinary average by five or six times. It also varies in 
 normal blood in different vessels ; thus arterial blood contains 
 more fibrin than venous blood, the blood of the splenic vein 
 contains very little, and that of the hepatic veins scarcely any 
 fibrin. The blood of infants contains less fibrin than that of 
 adults ; and in the latter months of pregnancy there is a con- 
 siderable augmentation of this constituent. 
 
 During an animal diet the amount of fibrin is greater than 
 during a vegetable diet; the quantity of fibrin is moreover 
 increased during prolonged fasting. 
 
 The blood of the herbivorous animals contains more fibrin 
 than that of the carnivorous, and the blood of birds even 
 more than that of the herbivorous animals. 
 
 A constant and great augmentation of the fibrin occurs in 
 inflammatory diseases, especially in acute articular rheuma- 
 tism and in pneumonia ; in these diseases it has been found 
 to exceed !--. No diseases are known in which there is a 
 constant diminution of the fibrin. 
 
 In the lymph and chyle this constituent occurs in con- 
 siderably less quantity than in the blood. 
 
 In inflammatory exudations we find fibrin in the fluid 
 contents of the serous cavities, or on the mucous membrane 
 (as in croup), or in the parenchyma of organs ; in these cases 
 it most commonly occurs in a state of spontaneous coagula- 
 tion. The fibrin occurring in exudations and transudations 
 occasionally differs essentially, both in its physical and 
 chemical characters, from true blood-fibrin, sometimes closely 
 resembling the syntonin or muscle-fibrin described in the 
 next paragraph.* 
 
 * On this subject I may refer to Memoirs by Gorup-Besanez, " On a pe- 
 culiar Modification of Fibrin," in Ann. d. Ch. u. Pharm. 1855, vol. xciv. 
 p. 166, and by Bodeker, " On the Analysis of a Transudation in the Pleural 
 Cavity," in Zeitsch. f. rat. Med. 1855, vol. vii. p. 142. 
 
FIBKIN 111 
 
 From what has been already stated, we feel justified in Its origin, 
 concluding that fibrin is formed from albumen and not 
 directly from the food. The slight excess of oxygen in fibrin 
 would lead to the inference that it is formed by a process of 
 oxidation. This inference has, however, led to serious error 
 in reference to the increase of fibrin in inflammation ; since 
 on the assumption that the fibrin is formed by a process of 
 oxidation, it was very erroneously concluded that the aug- 
 mentation of this constituent in inflammation is dependent 
 on an increased rapidity of the process of oxidation; and 
 that, consequently, inflammation is nothing more than an 
 actual process of combustion. This hypothesis was for many 
 years unhesitatingly accepted by physicians, without its appa- 
 rently occurring to them that, even if an excessive supply and 
 absorption of oxygen might, on purely chemical grounds, be 
 regarded as the cause of an increase of fibrin, this explana- 
 tion was altogether incompatible with the fact that in pneu- 
 monia, when a considerable portion of the lungs is rendered 
 impervious to air, a greater quantity of fibrin is found than 
 in almost any other disease. Physiological facts seem to 
 point to exactly the opposite hypothesis, that the augmenta- 
 tion of fibrin in inflammatory blood is caused by an insuffi- 
 cient supply of oxygen. When oxygen is abundantly intro- 
 duced into the blood, the fibrin rapidly undergoes further 
 transformations ; thus we find less of it in children and in 
 healthy adults than in pregnant women and in patients with 
 inflammatory diseases ; for in the latter cases the respiration 
 is more or less impeded, and the quantity of oxygen con- 
 veyed to the blood is not sufficient to effect the further 
 normal oxidation or transformation of the fibrin, which 
 therefore accumulates in the circulating fluid. 
 
 It has long been a disputed question whether fibrin be- Its physio- 
 
 . . logical im- 
 
 longs to the progressive or regressive metamorphosis ; that is p0 rtance. 
 to say, whether it is a factor in the elaboration or in the dis- 
 integration of the tissues. For a full discussion of the sub- 
 
112 PHYSIOLOGICAL CHEMISTRY. 
 
 ject I must refer to Lehmann's Physiological Chemistry, 
 vol. i. pp. 361-364., and to Simon's Lectures on General 
 Pathology, pp. 50-52. As in the process of acid ferment- 
 ation there are intermediate stages between the two extremes 
 of alcohol and acetic acid, so in the present case we may 
 regard fibrin as representing one of the stages of oxidation 
 which albumen undergoes in its transition into the more 
 highly oxidised elements of the tissues. 
 
 (104.) Syntonin*, QJ: muscle-fibrin) forms, while moist, a snow- 
 white coherent, somewhat elastic mass, which may be removed 
 from the filter on which it is collected, in the form of laminae 
 or membranes. The following are the most characteristic pro- 
 perties by which it may be distinguished from spontaneously 
 coagulated blood-fibrin, or from albumen. It differs from 
 the former by its being soluble' in water containing 0'1-g- of 
 hydrochloric a,cid, from which it is precipitated in a gela- 
 tinous form on the neutralisation of the acid ; by its insolu- 
 bility in nitre-water (6 parts of KO . N0 5 to 100 of water) ; and 
 by its swelling and becoming gelatinous, but not dissolving, 
 in a moderately concentrated solution of carbonate of potash ; 
 while it may be readily distinguished from the latter by the 
 fact that it is precipitated from its alkaline solutions by the 
 chlorides of sodium and potassium. That it is not iden- 
 tical with blood-fibrin is also obvious from the results of its 
 ultimate analysis. 
 
 We are indebted to Liebig for the discovery that syntonin, 
 which is the most important constituent of the fibrillse of 
 striated muscle, is chemically distinct from the fibrin of the 
 blood. Lehmann has subsequently shown that it not only 
 exists equally in the voluntary and involuntary (or smooth) 
 muscles, but in all those tissues in which Kolliker's fibre-cells 
 occur ; as, for instance, in the middle arterial coat and in the 
 spleen. 
 
 The fact that this substance is the principal constituent and 
 
 * Derived from awrefaur, to render tense. 
 
CASEIN. 113 
 
 the essential basis of all the contractile tissues, seems sufficient 
 to indicate its uses ; but how far, or why it is better qualified 
 than the other protein-bodies for the manifestations of vital 
 contractility, we cannot tell. 
 
 (105.) Casein chiefly differs from the other protein-bodies Casein. 
 in its mode of coagulation. Acetic and lactic acids throw 
 down casein from its solutions, the precipitate redissolving in 
 an excess of the acetic acid. Casein is coagulated by the 
 mucous membrane of the fourth stomach of ruminants (ren- 
 net) and by the gastric juice of carnivorous animals. It is 
 not precipitated by heat ; but if it be boiled with a solution of 
 sulphate of magnesia or of chloride of calcium, it is thrown 
 down in a state of combination with the magnesia or lime, 
 although it is not precipitated by heat; if, however, it be 
 exposed in an open vessel to a high temperature, a white, 
 tough membrane of coagulated casein soon forms on the sur- 
 face, and, when removed, is soon reproduced. Scherer has 
 shown that it cannot coagulate in this membranous form 
 unless in the presence of oxygen. 
 
 Notwithstanding the above peculiarities of casein, it is by 
 no means easy to distinguish it with certainty from alkaline 
 albuminates or acid solutions of albumen. The following 
 method is recommended by Lehmann for determining whe- 
 ther casein coexists with albumen in a fluid. The fluid must 
 be boiled for some time, a little hydrochlorate of ammonia 
 having been first added in order to remove the albuminate of 
 soda ; we then filter, and ascertain whether sulphate of mag- 
 nesia or chloride of calcium give a precipitate at the ordinary 
 temperature; if this be the case, the precipitate must be 
 removed by filtration before we boil the fluid with the view 
 of finding casein. If a precipitate is now caused by boiling, 
 it must consist of casein in combination with magnesia or 
 lime ; and it will be found that in this case rennet will also 
 coagulate the fluid. 
 
 Casein has been frequently analysed, but these analyses 
 
 i 
 
114 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 have not led to any certain empirical formula, much less to 
 a rational one.* 
 
 This substance occurs in the milk of all mammals. In 
 human milk it ranges from about 2 '7 to more than 3-g-; in 
 cows' milk it is rather more abundant ; and in that of car- 
 nivorous animals (the dog) it ranges from 8*3 to 13 -6^. In 
 the milk of the ass it does not exceed l'95.f 
 
 A substance very similar to casein occurs in small quantity 
 in the blood, and has received the name of serum-casein. It 
 seems to be more abundant in the serum of women than in 
 that of men (amounting in the former, according to Panum f, 
 to 0'3), and especially so during a certain time after delivery 
 (when it ranges from 0'99 to 1'25-g-). It is said, also, to exist 
 in excess in placental blood. 
 
 It likewise occurs in the interstitial juice of the muscles of 
 organic life (in short, wherever Kolliker's contractile fibre- 
 cells are found), in the expressed juice of the thymus gland 
 and of the connective and elastic tissues, and in the fluid of 
 the allantois. 
 
 Casein is, moreover, found in the yelk of egg. Here it 
 occurs in a state of intimate admixture with albumen, and 
 this admixture was until very recently looked upon as a 
 special protein-body, and has been described under the name 
 Qi Vitellin. 
 
 Nothing is accurately known regarding the origin of casein; 
 that is to say, we cannot tell whether it is primarily elaborated 
 from other protein-bodies in the blood, or in the mammary 
 glands: neither is it known why albumen the ordinary 
 nutrient matter is replaced in the milk by casein ; and we 
 are perfectly in the dark as to the functions exercised by 
 casein in the juices of the various tissues. 
 
 * See the Tabular View at the end of this Chapter, 
 f See the Chapter on " The Milk." 
 J Arch. f. Pathol. Anat. vol. iii. pp. 251272. 
 Arch. f. Physiol. Heilk. vol. xi. pp. 105111. 
 
 See also Moleschott, in 
 
GLOBULIN, 115 
 
 (106.) Globulin, or crystallin, closely resembles albumen; Globulin, 
 it, however, does not coagulate at a temperature lower than iin. CryS ' 
 163, when its solution either becomes milky or is converted 
 into a globular mass, according to its concentration. The 
 following reaction is characteristic of globulin: its solution 
 is not precipitated either by acetic acid or by ammonia, but 
 it becomes very turbid when the acid solution is neutralised 
 by ammonia, or the ammoniacal solution by acetic acid. 
 Grlobulin also presents the peculiarity of being precipitated 
 from its aqueous solution by carbonic acid, the precipitate 
 which is formed being again soluble in water, if the carbonic 
 acid be displaced by the introduction of another gas. 
 
 Grlobulin has hitherto only been detected with certainty in 
 the crystalline lens, where it amounts to nearly 36. Ber- 
 zelius held the view that this protein-body obtained from the 
 lens was identical with the coagulable matter of the red blood- 
 corpuscles, and hence assigned to the two the common name of 
 globulin a view which we shall show to be incorrect in the 
 next paragraph : it is sufficient here to state that the protein- 
 body contained in the blood-corpuscles is, under certain 
 conditions, crystallisable, while, under similar conditions, the 
 globulin of the lens cannot be made to assume the crystalline 
 form. 
 
 The object of the globulin in the fibres of the lens is too 
 obvious to require any remarks ; and it is interesting to ob- 
 serve, that while a refractive fluid is thus produced, the lens 
 itself is at the same time rendered achromatic, not merely by 
 its anatomical structure, but also by its central portion being 
 filled with a concentrated fluid which gradually becomes more 
 diluted towards the capsule.* 
 
 (107.) H&matocrystallin is the only one of the protein- Haemato- 
 
 crystailin. 
 
 * For the knowledge of this fact we are indebted to Chenevix, who found 
 that the specific gravity of an entire lens was 1-0765, while that of the nucleus 
 was 1-194. 
 
 1 2 
 
116 PHYSIOLOGICAL CHEMISTRY. 
 
 bodies that can be obtained in a crystalline state, and the 
 very forms of the crystals show us that we have to deal with 
 three or four different substances, or distinct modifications of 
 the same substance. This crystalline substance, when ob- 
 tained from the blood of guinea-pigs, rats, or mice, separates 
 in tetrahedra; that from the blood of man, and most carni- 
 vorous animals, in prisms ; that from the blood of the squirrel 
 in hexagonal plates ; and that from the hamster, in rhombo- 
 hedra. (Plate IV. jig. 4.) These crystals are devoid of smell 
 and taste, and are always of a red colour, but appear of a 
 lighter tint individually, when seen under the microscope. 
 The solubility of the different forms is very different; the. 
 prisms (from a dog) dissolving in 90 parts of water, while the 
 tetrahedra require 600 parts. . Hsematocrystallin differs from 
 all the other protein-bodies in not being precipitated from its 
 solutions by nitrate of silver, chloride of mercury (corrosive 
 sublimate), chloride of tin, or basic acetate of lead; it is, 
 however, thrown down by nitrate of suboxide of mercury and 
 bichromate of potash. The solution of the tetrahedral crys- 
 tals coagulates at 146-4; that of the other crystals requires 
 two or three additional degrees of temperature : the super- 
 natant fluid then reddens litmus. All these crystals so 
 obstinately retain the blood-pigment that it is impossible to 
 obtain them perfectly free from it. 
 
 The hsematocrystallin obtained from the blood of the dog 
 has been analysed by Lehmann, but its formula has not yet 
 been established. 
 
 This chemist has also made the remarkable discovery that 
 this substance may be broken up into a nitrogenous sub- 
 stance (which has not been fully investigated) and a variety 
 of sugar closely corresponding to, if not identical with, gly- 
 cose. In this manner we may ultimately discover its rational 
 formula. 
 
 Hsematocrystallin occurs only in the red blood-corpuscles. 
 
TABULAR VIEW. 
 
 117 
 
 It seems to be present in all the vertebrated animals. We 
 know nothing of its origin. - 
 
 Its uses are described in the chapter on "The Blood." 
 See 197. 
 
 TABULAR TIEW OF THE ULTIMATE COMPOSITION OF THE 
 PROTEIN-BODIES. 
 
 Protein, C 36 H 25 N 4 10 . 
 Carbon . . . 57-29 
 Hydrogen . * . : . 6-63 
 Nitrogen . . . 14-86 
 Oxygen . . . 21-22 
 
 Albumen (according to 
 Mulder's formula). * 
 
 Carbon . . . 52-97 
 
 Hydrogen . . 6-81 
 
 Nitrogen . . 15*11 
 
 Oxygen. . . 23-54 
 
 Sulphur . . 1-57 
 
 Blood-fibrin {analysed 
 by Mulder). 
 
 Carbon 
 
 Hydrogen 
 
 Nitrogen 
 
 Oxygen . 
 
 Sulphur 
 
 Phosphorus 
 
 52-7 
 
 6-9 
 
 15*4 
 
 23-5 
 
 1-2 
 
 0-3 
 
 Do. (according to Lieber- 
 kuhri s formula). 
 
 Carbon . , . 53-59 
 
 Hydrogen . . 6-95 
 
 Nitrogen . . 15-63 
 
 Oxygen. . .21-84 
 
 Sulphur . . 1-99 
 
 Muscle-fibrin (analysed 
 by Strecker). 
 
 Carbon . . . 55-23 
 
 Hydrogen . . 7-39 
 
 Nitrogen . . 15-84 
 
 Oxygen. . . 20-33 
 
 Sulphur . . 1-21 
 
 * In this formula, Mulder neglects the phosphorus, which, according to his 
 analysis, amounts to 0-4$. According to Lieberkuhn, pure albumen contains 
 no phosphorus. 
 
 I 3 
 
118 PHTSIOLOaiCAL CHEMISTKY. 
 
 Casein (analysed by Volcker). 
 
 Carbon , v r . . 53-61 
 
 Hydrogen. . . 7*14 
 
 Nitrogen . ~. /. 15-47 
 
 Oxygen . .;,__.. . 17*99 
 
 Sulphur . . . I'll 
 
 Phosphorus -, . '74 
 
 Hamatocrystallinfrom dog's blood (mean of three 
 analyses by Lehmanri). 
 
 Carbon . . . 55-28 
 
 Hydrogen . . , , 7'11 
 
 Nitrogen . .. . 17-33 
 
 Oxygen . . . 20-05 
 
 Sulphur . . . 0-23 
 
119 
 
 CHAPTER VIIL 
 
 PROXIMATE DERIVATIVES OF THE PROTEIN- 
 BODIES. 
 
 (108.) THE substances belonging to this group differ very Their ge- 
 much from one another in their physical and their chemical 
 properties ; almost their sole points of correspondence being 
 that they only occur in the animal body, where they form the 
 bases of certain tissues, that they are neutral, insoluble in cold 
 water, and that they all contain nitrogen. In their behaviour 
 towards acetic acid and ferrocyanide of potassium, and towards 
 strong hydrochloric and nitric acids, they exhibit none of the 
 essential characteristics of the protein-bodies. 
 
 The following are the only substances of this group which 
 have hitherto been submitted to an accurate chemical 
 examination : 
 
 Grlutin-yielding substance, or ossein; 
 
 Chondrin-yielding substance ; 
 
 Elasticin, or the substance of elastic tissue *, 
 
 Fibroin; and 
 
 Chitin. 
 
 (109.) The term ossein was first applied by Robin and Ossein. 
 Verdeil, and subsequently by Fremy*, to the substance in 
 the osseous tissue which yields glutin. It is obtained by 
 the prolonged action of dilute hydrochloric acid on bone, 
 which must be subsequently washed repeatedly with water, 
 and treated with alcohol and ether. It is insoluble in water, 
 
 * In his " Recherches Chimiques sur les Os." Ann. de Chim. et de Phys. 1855. 
 vol. xliii. p. 51. 
 
 I 4 
 
120 PHYSIOLOGICAL CHEMISTRY. 
 
 but is converted into glutin (one of the forms of gelatin) 
 by the action of boiling water a transformation which is 
 very much facilitated if a little acid be present. The ossein 
 yielded by different kinds of animals requires different times 
 for its conversion into glutin, and the ossein of young animals 
 changes more rapidly than that of adults of the same 
 species. Fremy's analyses show that ossein is isomeric 
 with the glutin which it yields: moreover, the amount of 
 glutin is precisely the same as that of the ossein that 
 yields it. It appears to exist in the bones in a state of 
 freedom ; that is to say, not in combination with any of the 
 salts of lime, 
 
 Glutin, when in a pure state, is colourless, transparent, 
 of a horny appearance, brittle, heavier than water, and devoid 
 of smell and taste ; it is especially characterised by its solu- 
 bility in hot water, from which it gelatinises on cooling. It 
 is precipitated from its hot watery solution by chlorine, 
 chloride of mercury (corrosive sublimate), bichloride of pla- 
 tinum, tannic acid, and alcohol. On dry distillation, it yields 
 large quantities of the volatile alkaloids Petinine (C 8 H U N) 
 and Picoline (C 12 H 7 N), together with carbonate of ammonia : 
 with chromic acid it yields the same products of decomposi- 
 tion as the protein-bodies, but a much larger quantity of 
 valerianic acid : with alkalies, it yields an abundance of leucine 
 and glycine. 
 
 We are unable to assign, with any degree of certainty, a 
 chemical formula to glutin. Its ultimate composition is given 
 at the end of this chapter ; but since this analysis was made, 
 it has been found to contain from 0*12 to 0'14- of sulphur. 
 
 Grlutin may be obtained, by mere boiling, from various 
 tissues ; not only from bone-cartilage (after its ossification), 
 but from the tendons, the skin, the bladder, &c. 
 
 As far as we yet know, glutin only normally occurs pre- 
 formed in the juice of the spleen (Scherer) ; it is sometimes 
 found in the blood in the diseased condition known as 
 
GLUTIN CHONDRIN. 121 
 
 leucaemia (see 221), and is an occasional constituent of pus 
 (Spiess, Weismann), and of the expressed juice of carcino- 
 matous tumours (Schirmer and Wimmer). 
 
 Since cartilage and connective tissue yield, when sub- 
 mitted to ultimate analysis, precisely the same results as the 
 glutin that can be obtained from them, it is probable that 
 one is convertible into the other by a mere re-arrangement of 
 the atoms. 
 
 It is remarkable that the embryo, as long as it remains in 
 the egg, contains no gelatigenous tissue (Hoppe). 
 
 We know nothing of the- conditions under which the sub- 
 stance which yields glutin is formed from the protein-bodies ; 
 that there are intermediate or transition stages between the 
 two, is borne out by Scherer's observation that leucsemic 
 blood sometimes contains, not only glutin, but a substance 
 which, in its chemical relations, stands between it and the 
 protein-bodies. 
 
 It is very evident that those tissues of the animal body 
 which yield gelatin rank low in the scale of organisation, and 
 that their uses are almost entirely of a physical character : 
 thus they form strong points of connection for muscles (the 
 tendons), they moderate shocks or concussions by their elas- 
 ticity (the cartilages of bone), they protect the body from 
 rapid changes of temperature by their bad conducting power 
 (the skin), and they are of service through their transparency 
 (the cornea). 
 
 (110.) The substance which yields chondrin, that is to say, Chondrin. 
 the organic matter contained in the permanent and articular 
 cartilages and the nbro-cartilages, as well as bone-cartilage 
 before ossification, has never yet been carefully examined. 
 Hence we must confine our remarks to chondrin itself, the 
 variety of gelatin that is yielded by these substances in the 
 same manner that bone yields glutin. Chondrin closely 
 resembles glutin in its physical characters, except that it is 
 usually more coloured, and swells to a greater extent (to 11 
 
122 PHYSIOLOGICAL CHEMISTRY. 
 
 or 12 times its original size) in cold water. It differs from 
 glutin in being precipitated by hydrochloric acid, acetic acid, 
 acetate of lead, alum, and sulphate of peroxide of iron, as 
 well as by the reagents mentioned as throwing down gelatin. 
 When treated with strong sulphuric acid it yields leucine, but 
 no glycine ; but when treated with a concentrated solution of 
 potash, or fused with hydrated potash, it yields leucine, 
 glycine, and other products of decomposition, amongst which, 
 however, Hoppe, who has carefully studied this substance, 
 could not detect tyrosine. When oxidised with chromic acid, 
 it developes much hydrocyanic acid, but no formic or acetic 
 acid. 
 
 Chondrin has been analysed by Mulder and by Scherer, 
 and the results of the former are given in the Tabular View 
 at the end of this chapter. In addition to the four ordinary 
 elements, Mulder found 0'38 of sulphur, and about 4-g- of 
 phosphate of lim'e which seemed to be chemically combined 
 with the other elements. 
 
 Bone-cartilage before ossification yields chondrin ; and the 
 same is the case in various diseases of the osseous tissue. 
 Hence chondrin and glutin must stand in a definite relation 
 to one another, although we do not yet know what that rela- 
 tion is. 
 
 In his recent memoir on the chemistry of pus, Bodeker 
 states that chondrin occasionally occurs in that fluid. 
 
 The uses of the chondrin-yielding substances are much the 
 same as those of the substances yielding glutin. 
 
 Elasticin. (HI-) Elasticm, or the substance of elastic tissue, is in- 
 soluble in all known menstrua: it requires thirty hours' 
 boiling in a Papin's digester at a temperature of 320 to 
 reduce it to a brown fluid, which does not gelatinise on 
 cooling. With strong sulphuric acid, it yields leucine, but no 
 glycine. 
 
 It occurs in connective tissue (in the form of nuclear fibres), 
 and is most abundant in the true elastic tissue, as, for in- 
 
CHITIN. 123 
 
 stance, in the ligamentum nuchge, the ligamenta subflava, the 
 inferior vocal chords, and the middle arterial coat. 
 
 Its uses are of a purely physical character. 
 
 (112.) Fibroin has hitherto been obtained only from silk Fibroin, 
 and gossamer threads, and is consequently a substance of little 
 general interest. A similar substance has been obtained from 
 sponge. 
 
 (113.) Chitin is a white amorphous substance, which gene- Chitin. 
 rally retains the form of the tissue from which it is derived. 
 It is insoluble in water, acetic acid, and alkalies, but dissolves 
 with decomposition in the strong mineral acids. It presents 
 two peculiarities when submitted to dry distillation : it does 
 not fuse, but leaves a carbonaceous mass which, on microscopic 
 investigation, always exhibits the form of the original tissue ; 
 and further, notwithstanding it contains nitrogen, it yields 
 acid products of distillation, from which it may be inferred 
 that a carbo-hydrate enters into its composition. 
 
 The analyses of chitin instituted by Schmidt and Lehmann 
 differ very slightly from one another. From his analysis, 
 Schmidt calculates for it the formula C 17 H 14 NO n . 
 
 Chitin forms the true skeleton of all insects and Crustacea, 
 constituting not merely their external skeleton, but (in the 
 case of insects) materially entering into the composition of 
 the tracheae and intestinal canal. 
 
 (113.*) TABULAR VIEW OF THE PROXIMATE DERIVATIVES OF 
 THE PROTEIN-BODIES. 
 
 Ossein (Fremy). Glutin yielded by it (Fremy). 
 
 Carbon . . . 49-21 Carbon . . . 50-40 
 
 Hydrogen . . 6-50 Hydrogen .. . 6-50 
 
 Nitrogen . . 17'86 Nitrogen . . 17-50 
 
 Oxygen . . . 25-14 Oxygen . . . 26-00 
 
124 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Chondrin (Mulder). 
 
 Carbon . . . 49-97 
 
 Hydrogen . . 6-63 
 
 Nitrogen . . 14-14 
 
 Oxygen . . . 28-59 
 
 Sulphur. . . 0-38 
 
 Chitin (Lehmann). 
 
 Carbon . . . 46*73 
 
 Hydrogen . . 6-59 
 
 Nitrogen . . 6-49 
 
 Oxygen . . . 40-18 
 
125 
 
 CHAPTER IX. 
 
 THE INORGANIC CONSTITUENTS OF THE ANIMAL 
 
 BODY. 
 
 (114.) OUR knowledge of the mineral substances occurring Inorganic 
 in organised bodies (whether plants or animals) is much less tuents" 
 perfect than might be supposed would be the case, considering 
 the general accuracy of inorganic analyses at the present day. 
 The principal reason of this defective knowledge is, that we 
 usually only attempt to determine these substances from the 
 ash left on incineration, a process which expels volatile 
 acids and salts of ammonia, decomposes organic salts, and 
 causes an almost complete re-arrangement of the various con- 
 stituents, so that from the composition of the ash we are 
 unable to draw any trustworthy conclusion regarding the 
 exact nature of the pre-existing substances :* and, we may 
 add as a secondary reason, that most of the analytical me- 
 thods that have been applied to the investigation of the 
 ashes of organic bodies, have not been of a nature to lead to 
 very accurate results. 
 
 We may divide the mineral substances occurring in the 
 animal body into three classes : 
 
 * I may point out one or two of the chief causes of difference between the 
 preformed mineral substances and those occurring in the ash. On incinerat- 
 ing a protein-body, or one of its proximate derivatives containing sulphur or 
 phosphorus, this sulphur or phosphorus will pass into the ash in the form of 
 sulphuric or phosphoric acid (in combination with a base), if there be free access 
 of air during combustion. Again, at a very great heat, common phosphate of 
 soda abstracts a portion of the base, not only from alkaline carbonates, but even 
 from alkaline sulphates and chlorides, so that an ash may have lost all its 
 alkaline carbonate and a portion of its hydrochloric and sulphuric acids. 
 
126 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Their di- 
 vision into 
 three 
 classes. 
 
 1. Those which are chiefly of service from their physical 
 characters. In this class we especially include those wnich 
 by their deposition give strength and power of resistance to 
 the solid tissues. 
 
 2. Those which are chiefly of service from their chemical 
 characters, taking an active part in the metamorphosis of 
 tissue, and in the most important vital functions. 
 
 3. Those which are only incidentally retained in the or- 
 ganism, or which, originating in the metamorphosis of tissue, 
 are to be regarded as mere products of excretion. 
 
 Substances 
 useful from 
 their physi- 
 cal proper- 
 ties. 
 
 SUBSTANCES USEFUL FROM THEIR PHYSICAL CHARACTERS. 
 
 (115.) In this class we may place 
 
 Water (which might equally be placed in the second 
 
 class), 
 Phosphate of lime, 
 Carbonate of lime, 
 Phosphate of magnesia, 
 Fluoride of calcium, and 
 Silicic acid. 
 
 (116.) Water is a substance of whose uses in the animal 
 organism it is superfluous to speak. The physical properties 
 of many tissues depend upon the water which is mechanically 
 combined with them. All chemical processes going on in the 
 animal body require the co-operation of water ; and the in- 
 fluence of this substance on nutrition and secretion is very 
 marked, as will be shown in a future part of this volume. 
 
 (117.) Phosphate of lime affords the most striking illustra- 
 tion of this class of bodies, since it is to it that the osseous 
 skeleton mainly owes its -firmness and hardness. Thus, when 
 too little phosphate of lime is taken into the system with the 
 food (as in Chossat's well-known experiments), or when cer- 
 tain physiological processes make a special demand for this 
 salt (as during pregnancy when the foetal bones require it for 
 
PHOSPHATE OF LIME. 127 
 
 their ossification, and during the period of dentition), the 
 bones lose more or less of their firmness, and fractures do not 
 readily heal. In all diseases of bone there seems to be a 
 greater relative diminution of this salt than of any other 
 essential substance ; but when the permanent cartilages un- 
 dergo the change commonly described as ossification, they are 
 found to contain an abnormal quantity of phosphate of lime. 
 
 Of all parts of the body the teeth are the richest in this 
 substance, which is most abundant in the enamel. 
 
 There is some doubt as to the exact composition of the 
 phosphate of lime occurring in these hard parts of the body. 
 Berzelius was of opinion that it was represented by the 
 formula 8Ca0.3P0 5 ; while Heintz, whose investigations were 
 carried on under the superintendence of Rose, was led to 
 regard 3CaO . P0 5 as the correct formula. 
 
 Although there are no parts of the body in which phosphate 
 of lime occurs near so abundantly as in the bones and teeth, 
 yet there is no texture in which it is not present, or at all 
 events which does not yield it on incineration. Liebig 
 considers that the insolubility of various tissues, as, for 
 instance, muscular fibre and connective tissue, in water, and 
 their solubility in dilute hydrochloric acid (as in the di- 
 gestive process) is, in a great measure, dependent on the 
 phosphate of lime which they contain. Thoroughly dried 
 muscular fibre contains about 1 - of this salt. 
 
 Phosphate of lime occurs in solution in all the animal 
 fluids, where it is generally (except in the urine) combined 
 with the dissolved protein-bodies contained in them. There 
 can be no doubt that it is chemically combined with them, 
 and that it takes a part in the changes which they undergo, 
 both in their progressive metamorphosis into tissue and in 
 their regressive metamorphosis into products of excretion. 
 The protein-bodies are thus the conveyers of the phosphate of 
 lime to the cells and tissues. Among the various facts which 
 may be brought forward in support of the view that phosphate 
 
128 PHYSIOLOGICAL CHEMISTRY. 
 
 of lime is indispensable to cell-formation, we may mention 
 that in the mantle of the molluscs (where new cells for the 
 formation of shell abound) more of this salt is accumulated 
 than is found in any other part of the animal. 
 
 A large quantity of phosphate of lime occurs in animal con- 
 cretions, where it exists in an amorphous state. Schlossberger 
 once found it in a crystalline form in a urethral calculus. 
 
 The quantity of phosphate of lime in the urine is dependent 
 on the quantity of this substance occurring in the food, and 
 on the demands of the organism for this salt. From the 
 great demand on the part of the foetus for this substance, we 
 commonly find that, during the latter months of pregnancy, 
 the urine hardly contains more than traces of it, even when 
 the diet has been sufficiently ^abundant. In the urine of 
 herbivorous animals it is very much less abundant than in 
 that of the carnivora, because in the former the supply of cal- 
 careous salts, yielded by the food, scarcely exceeds the demands 
 of the system. 
 
 Although by far the greatest quantity of the phosphate of 
 lime found in the body has, doubtless, been introduced into 
 the system from without, yet it is unquestionable that a por- 
 tion of it is formed within the organism from other lime-salts 
 (especially carbonate of lime) and from the phosphates which 
 must be formed in the regressive metamorphosis of the 
 phosphorus-containing tissues. This process of formation of 
 phosphate of lime from its proximate constituents may be 
 almost directly observed in the development of the chick 
 within the egg, for it has been shown by Prout's observations 
 that so much carbonate of lime is transferred, during incuba- 
 tion, from the shell to the yelk, as to explain the augmentation 
 of the phosphate of lime (in so far as the lime is concerned) 
 during the growth of the chick within the egg. The origin 
 of the additional phosphoric acid is explained in this manner : 
 part of the phosphorus of the yelk exists in the form of 
 glycero-phosphoric acid, which, during incubation, becomes 
 
CARBONATE OF LIME. 129 
 
 gradually decomposed ; so that the liberated phosphoric acid , 
 unites with the lime-salt, which we have already described as 
 being transmitted from the shell to the yelk. 
 
 (118.) Carbonate of lime is the main ingredient of the Carbonate 
 shell of invertebrate animals ; it likewise occurs in compara- 
 tively small quantity in the bones of the vertebrata ; and in 
 these cases it seems to serve the same purpose as phosphate 
 of lime. 
 
 - It occurs in a state of solution, being dissolved by the free 
 carbonic acid, in various animal fluids, as, for instance, in the 
 parotid saliva (especially of the horse and dog), in the urine 
 of herbivorous animals, and, probably, also in their blood. It 
 is sometimes found in human urine with an alkaline reaction. 
 
 It is a very common constituent, in greater or lesser quan- 
 tity, of many concretions. 
 
 The only part of the human organism in which it is said to 
 occur normally, in a crystalline state, is in the saccule of the 
 vestibule of the internal ear. 
 
 In many cases there can be no doubt that the carbonate of 
 lime is a mere product of incineration ; but, independently of 
 this possible source of error, we have sufficient evidence that 
 this salt actually exists in the tissues and fluids which we 
 have named. Its origin must be chiefly referred to our 
 vegetable food, and to the water used for drinking; it is 
 possible, however, that it may also be formed, to a certain 
 extent, in the blood by the decomposition of organic lime- 
 salts. 
 
 Its solubility in the animal fluids has been variously ex- 
 plained. Free carbonic acid is, probably, its ordinary solvent ; 
 but it is also more or less soluble in solutions of the alkaline 
 chlorides and of various organic matters, as, for instance, 
 sugar. 
 
 (119.) Phosphate of magnesia, in small quantity, is always Phosphate 
 associated with phosphate of lime, and, like the latter salt, s i a . & 
 occurs chiefly in the bones. 
 
130 PHYSIOLOGICAL CHEMISTRY. 
 
 It is proved by ash-analyses that a little phosphate of mag- 
 nesia is present in all animal fluids and tissues ; and a still 
 more simple evidence of its existence is afforded by allowing 
 them to undergo decomposition, when, on the development of 
 ammonia, the well-marked crystals of phosphate of ammonia 
 and magnesia may be recognised by the microscope (PL IV. 
 Jig. 5.). 
 
 It is found in the faeces in relatively larger quantity than 
 phosphate of lime, which led Berzelius to the idea that the 
 lacteals were less disposed to absorb the magnesian than the 
 lime-salt. There is, however, no necessity for such a hypo- 
 thetical explanation, for, independently of the fact that a 
 considerable quantity of phosphate of magnesia is absorbed by 
 the intestine, as is evidenced by its presence in the urine, its 
 tendency to form an insoluble crystalline salt with ammonia 
 (which is always found in the faeces, and often forms large 
 intestinal concretions in herbivorous animals) would suffice to 
 explain its comparative abundance in the excrements. 
 
 The abundance of this salt in the seeds of the cereals and in 
 the other ordinary articles of vegetable diet sufficiently ex- 
 plains its presence in the system. A far less amount of this 
 salt than of the corresponding lime-salt seems to be required 
 by the organism, as is shown by the relative quantities in 
 which they occur in bone ; and, as is further indicated by the 
 fact, that far more of this than of the lime-salt escapes intes- 
 tinal absorption. 
 
 Fluoride of (120.) Fluoride of calcium occurs in minute quantity in the 
 calcium. -^oneg an( j teeth. It is usually much more abundant in these 
 parts in fossil than in recent animals: it is very probable, 
 however, that this excess is dependent on a process of infiltra- 
 tion rather than on an original peculiarity in the composition 
 of the textures. 
 
 It has been shown by Professor George Wilson * that dis- 
 
 * Although these researches were published more than ten years ago, and 
 the results noticed in many of the scientific journals of the time, M. Nickles, a 
 
SILICIC ACID. 131 
 
 tinct traces of this substance may be exhibited in the blood, 
 milk, &c. 
 
 The origin of this substance must be referred to the food. 
 Many mineral waters contain traces of fluorides, and it is pos- 
 sible that vegetables may also take up a little of it from the 
 soil. 
 
 (121.) Silicic acid forms the groundwork of the shields of Silicic acid, 
 many of the infusoria in the same manner that phosphate and 
 carbonate of lime are the means of affording strength and re- 
 sisting power to the bones of the vertebrata and shells of 
 molluscs and crustaceans. 
 
 In the higher animals it appears to be an integral con- 
 stituent of feathers, wooj, and hair. Small quantities of it 
 have been found in the blood and in the eggs of birds ; and 
 traces of it have occasionally been detected in the blood, bile, 
 and urine of man and various animals. 
 
 In the solid excrements we always find silicic acid, partly 
 in the form of actual sand, and partly derived from the 
 vegetable tissues of the food. 
 
 SUBSTANCES CHEMICALLY SEEVICEABLE. 
 
 (122.) In this group we place; 
 
 Hydrochloric acid, 
 Chloride of sodium, 
 Carbonate of soda, 
 The alkali-phosphates, 
 Ammonia and its salts, and 
 Iron. 
 
 (123.) Hydrochloric acid never occurs free except in the Hydro* 
 gastric juice, and even there it possibly exists as a conjugated ^^ 
 
 Trench chemist, has recently announced the presence of fluorine in the blood 
 as a new fact of his own discovery. See the Philosophical Magazine, March, 
 
 1857. 
 
 K 2 
 
132 PHYSIOLOGICAL CHEMISTRY. 
 
 acid (see the Chapter on " The Gastric Juice "). Unless the 
 gastric juice be distinctly acid it does not possess its cha- 
 racteristic digestive action; and the only acid which can 
 physiologically replace hydrochloric acid in this fluid is lactic 
 acid. 
 
 By what chemical process the hydrochloric acid is liberated 
 in the gastric glands is at present unknown. 
 
 (124.) Chloride of sodium is a substance whose importance, 
 in relation to the metamorphosis of the tissues, is clearly shown 
 by the fact of its occurrence in all the animal solids and fluids, 
 in the latter of which (if we except the expressed juices of the 
 muscular tissue and of the thymus gland, and the yelk of egg) 
 it forms the greater part of the soluble ash-constituents ; and, 
 by the circumstance that its amount in the blood is nearly 
 constant, whatever may be the quantity of salt taken with the 
 food. The influence of this salt in modifying the characters 
 of the protein-bodies .is very remarkable; it augments the 
 solubility of albumen, and the coagulation of this substance 
 varies with the amount of salt that is present ; it acts as a 
 solvent to pure casein, and hinders, in an extraordinary de- 
 gree, the coagulation of the fibrin of the blood. There is no 
 certain evidence that it enters into chemical combination with 
 these bodies, but it is more than probable that it does so, from 
 the influence which it exerts on them, from the analogous 
 compound which it forms with glycose, and from the impos- 
 sibility of separating it from them by mere washing. It 
 would also seem as if active cell-formation specially required 
 the presence of salt ; -at all events cartilage, which in its per- 
 fectly developed stage is singularly rich in cells, contains more 
 of this substance than any other tissue ; and the cartilaginous 
 bones of the foetus, in which there is comparatively little de- 
 position of phosphate of lime, contain far more salt than the 
 bones of the adult.* 
 
 * Lehmann found that the laryngeal cartilages of an adult woman yielded 
 an ash containing 1 1 236g of chloride of sodium ; and while various adult 
 
CHLORIDE OF SODIUM CARBONATE OF SODA. 133 
 
 The following table gives, at a glance, the relative quan- 
 tities of chloride of sodium contained in the chief animal 
 fluids ; a represents the per-centage in the fluid itself, b in its 
 solid residue, and c in the ash : 
 
 . b. c. 
 
 Human blood (L.) * . . 0-421 1-931 57-641 
 
 Blood of horse (L.) . . 0-510 2-750 67H05 
 
 Blood of cat (N.) . . 0-537 2-286 67-128 
 
 Chyle of horse (L.) . . 0-531 8-313 67-884 
 
 Chyle of cat (N.) . . 0-710 7-529 62-286 
 
 Human saliva (L.) . . 0-153 12-988 62-195 
 
 Human mucus (N.) . . 0-583 13-100 70-000 
 
 Serum of pus (N.) . . 1-260 11-454 72-330 
 
 Pleuritic exudation (S.) . 0-750 10-416 73-529 
 
 The sources from whence we derive the salt found in the 
 body are too obvious to require notice. 
 
 The uses of this substance will be fully considered in the 
 Chapter on " The Metamorphosis of the Tissues." 
 
 (125.) Carbonate of soda is an ordinary ingredient of the Carbonate 
 ash yielded by the combustion of organic matters; in this 
 case it is, however, usually only a product of decomposition, 
 induced by a high temperature on the compounds of soda 
 with organic acids or with the protein-bodies. It has been 
 proved to exist preformed, in combination with other soda- 
 compounds, in the blood and in the lymph. (As a mean of 
 ten experiments, Lehmann found 0*1628g of carbonate of soda 
 in ox-blood, and Nasse found 0-056^- in the lymph of a horse). 
 It occurs in the urine of herbivorous animals in association 
 with the carbonates of potash and lime. 
 
 The uses of this salt in the blood and other fluids will be 
 
 bones yielded only from 7 to l-5g, the femur of a six-months' foetus yielded 
 10-138g. 
 
 * In the above table (L.) indicates that the analysis was made by Lehmann, 
 (N.) by Nasse, and (S.) by Scherer. 
 
 K 3 
 
134 PHYSIOLOGICAL CHEMISTRY. 
 
 noticed in the Chapter on "The Metamorphosis of the Tissues;" 
 the principal object which it effects in the blood, probably, is 
 to neutralise the acids conveyed into or developed within the 
 organism. 
 
 (126.) The alkali-phosphates are found in most of the 
 animal fluids, where, however, they occur in very different 
 quantities, as may be seen by a reference to the subjoined 
 table. It is worthy of notice that they seem to stand in an 
 inverse ratio to the chloride of sodium, in the same manner 
 as the potash-salts preponderate where the soda-salts are 
 scanty. Thus they are in excess in the blood-corpuscles, in 
 the yelk of egg, and in the expressed juices of the muscular 
 tissue and of the thymus gland, and are found in only small 
 quantities in the alkaline fluids, &s the serum of the blood, the 
 white of egg, &c. As they occur chiefly in acid fluids, we 
 must conclude that the acid phosphate of potash is the prin- 
 cipal alkali-phosphate in these cases. 
 
 The quantity in which they exist in the urine varies partly 
 with the amount in which they occur in the food, and partly 
 with the rapidity of the regressive metamorphosis of the 
 tissues, in which the phosphorus of the organic matters 
 becomes oxidised into phosphoric acid, which at once unites 
 with alkaline bases. The following results were obtained 
 from analyses made in Eose's laboratory at Berlin ; a repre- 
 sents the soluble salts in 100 parts of ash, and b the per- 
 centage of alkali-phosphates in a : 
 
 b. 
 3KO.P0 5 = 1-58 
 
 I JJJ? 
 
 3KO.P0 5 =21-60 
 
 
 a. 
 
 Ox-blood . 
 
 . 60-90 
 
 Horse-flesh . 
 
 . 42-81 
 
 Cows'-milk . 
 
 34-17 
 
 Yelk of egg . 
 
 . 40-95 I 
 
AMMONIA AND ITS SALTS. 135 
 
 White of egg . 81-85 
 
 n ,., (3KO.P0 5 = 6-78 
 
 Ox-bile. . . 90-85 { 3 NaO . P0 5 = 14-51 
 
 Urine 90-87 J2KO.P0 5 = 16-12 
 
 (3KO.P0 5 = 4-55 
 
 Solid excrements 18-55 3KO.P0 5 =20-13 
 
 The uses of the alkali-phosphates will be seen in our re- 
 marks on Exudations, and on the Metamorphosis of the Tissues. 
 
 (127.) Ammonia and its salts have been regarded by all Ammonia 
 recent chemists as of much more rare occurrence in the 
 organism than was formerly supposed. 
 
 According to Lehmann, the blood, chyle, lymph, milk, and 
 fluids of the egg contain, in their normal state, either no am- 
 monia or only most minute traces of it ; but in certain diseased 
 conditions, especially in typhus, variola, and scarlatina, it has 
 been shown by Winter and others to occur, as a carbonate, in 
 the blood in considerable quantity. 
 
 Dr. Richardson, in his Astley Cooper Prize Essay, has, 
 however, announced the startling discovery that ammonia is 
 the agent which retains the fibrin of the circulating blood in 
 a state of solution, and that on its exhalation as the blood is 
 exposed to the air, in the process of being abstracted, the pre- 
 cipitation of the fibrin depends. 
 
 I am indebted to the kindness of Dr. Eichardson for an 
 account of the following beautiful experiment, showing the 
 presence of ammonia in the blood. On moistening the in- 
 terior of the surface of a cupping-glass with a little hydro- 
 chloric acid before applying it to the incised part, we find 
 that, as the escaping blood exhales its gases, patches of crystals 
 of hydrochlorate of ammonia, visible to the naked eye, and of 
 whose microscopical characters and chemical constitution there 
 can be no doubt, are formed in the upper part of the glass. 
 
 K 4 
 
136 PHYSIOLOGICAL CHEMISTRY. 
 
 It has been established by Marchand, Keuling, and others, 
 that ammonia is present in the pulmonary exalation, and it 
 was also known as a constituent of the urine ; Dr. Kichardson 
 proves that it is likewise given freely off by the skin, and 
 that it may be detected in the saliva and the serous fluids. 
 
 In cases of advanced albuminuna, carbonate of ammonia, 
 arising from the decomposition of non-eliminated urea, is 
 found in the gastric juice. Many pathologists now hold that 
 the comatose symptoms which occur in the last state of 
 uraemia are due not to urea, but to carbonate of ammonia, 
 accumulating in the blood. 
 
 It is almost unnecessary to observe that ammoniacal salts 
 are developed during the decomposition of almost all the 
 tissues. 
 
 Iron. (128.) Iron is found in different states of combination in 
 
 different parts of the animal body. In the hasmatin of the 
 blood it seems to exist in an unoxidised state in combination 
 with the other organic elements of that pigment, while in the 
 gastric juice it is found as a protochloride, and in other fluids, 
 as, for instance, the splenic juice, as a phosphate of the per- 
 oxide. We are altogether ignorant of the part which it plays 
 in the animal economy, but its occurrence in the ashes both 
 of milk and of the egg indicates the importance of its 
 function. 
 
 Any excess of iron in the system is, probably, eliminated by 
 the liver and the hair-follicles ; considerable quantities of it 
 being found in the ashes both of bile and hair. 
 
 Its origin must be referred to the iron contained in our 
 food, and frequently in the water that we drink. 
 
THE ALKALI-SULPHATES. 137 
 
 SUBSTANCES INCIDENTALLY PRESENT. 
 
 (129.) In this group we place : 
 
 The alkali-sulphates, 
 
 Carbonate of magnesia, 
 
 Manganese, 
 
 Arsenic, 
 
 Copper and lead, and 
 
 Sulphocyanides of potassium and sodium. 
 
 (130.) The alkali-sulphates occur in considerable, but in Sulphates 
 very fluctuating quantity in the urine, in only a small quan- alkalies 
 tity in the blood, and are not to be detected in the milk, in 
 the fluids of the egg, in the gastric juice, or in the bile. It is 
 true that the ashes of blood and of other fluids rich in protein- 
 bodies usually yield considerable quantities of the alkali-sul- 
 phates, but these are, for the most part, formed during the 
 process of incineration by the oxidation of the sulphur. Any 
 excess of these salts in the blood seems to be at once carried 
 off by the kidneys. 
 
 The circumstances modifying the quantity of alkali-sul- 
 phates in the urine will be noticed in the chapter on the 
 fluid. 
 
 It has been ascertained by von Bibra that the bones of 
 reptiles and fishes present the peculiarity of containing con- 
 siderable quantities of sulphate of soda. 
 
 It has been shown by experiment that small quantities of 
 alkali-sulphates are converted in the intestinal canal into the 
 corresponding sulphides (sulphurets), and hence it might be 
 inferred that these salts contributed to the formation of such 
 animal substances as contain sulphur, as, for instance, horny 
 tissue, although their formation may be otherwise (and per- 
 haps more correctly) explained when we recollect that many 
 articles of food contain unoxidised sulphur which might be 
 
138 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Carbonate 
 of magne- 
 sia. 
 
 Man- 
 ganese. 
 
 Arsenic. 
 
 thus employed. The absence of alkali-sulphates, both in milk 
 and in the fluids of the egg, seems tq indicate that they do 
 not take any very active part in the development of the 
 textures. 
 
 (131.) Carbonate of magnesia occurs very sparingly in the 
 bones, teeth, and egg-shells ; but is often found in considerable 
 quantity in the urine of herbivorous animals. It has been 
 not unfrequently observed in animal concretions of various 
 kinds. As the only magnesian salt found in the cereals and 
 grasses is the phosphate, it is more than probable that the 
 carbonate found in the urine of the herbivorous animals is 
 formed within the organism (either in the blood or in the 
 tissues during their regressive metamorphosis) by the action 
 of organic lime-salts on phosphate of magnesia, the resulting 
 magnesian salt (malate, tartrate, &c.) being reduced in the 
 blood to a carbonate. 
 
 (132.) Manganese, the almost universal associate of iron, is 
 found in small quantities in those parts of the organism in 
 which iron normally occurs, especially the blood and hair. 
 Like most of the metals, its excess is eliminated by the liver, 
 and hence we find it in a larger proportion in the bile than 
 elsewhere. Burin du Bouisson found that on an average 
 human blood contains 00078^- of red oxide of manganese, 
 Mn 3 4 , while the average percentage of iron is 0*05 ; in the 
 bile, on the other hand, Weidenbusch found that red oxide of 
 manganese stood to the peroxide of iron in the ratio of 1 : 2. 
 
 It is occasionally a constituent of gall-stones, and has been 
 found in urinary calculi. 
 
 Arsenic was at one time regarded (especially by Devergie 
 and Orfila) as a normal constituent of the bones ; but this 
 view has been since proved to be erroneous. From experi- 
 ments on animals (chiefly horses and rabbits) it appears that 
 arsenic, when given in considerable doses, is rapidly eliminated 
 by the great excreting organs, the liver and kidneys, and that, 
 consequently, it is found most abundantly in their tissues and 
 
SULPHOCYANOGEN. 139 
 
 in the fluids which they secrete ; it may likewise be found in 
 lesser quantities in the heart, lungs, brain, and muscles ; but 
 it does not enter the osseous tissue. 
 
 Copper and lead have no more claim than arsenic to be re- Copper 
 garded as normal constituents of the human body. After 
 their administration (either medicinally or accidentally) they 
 are retained for some time in the system, and are finally 
 eliminated by the liver ; hence they are more frequently 
 found in the bile and in gall-stones than elsewhere. Copper 
 is, however, an ordinary constituent of the blood and of the 
 liver of numerous of the invertebrate animals (crustaceans, 
 cephalopods, ordinary molluscs, and ascidians). 
 
 (133.) Sulphocyanogen, in combination with potassium or g u ipho- 
 sodium, has, as yet, only been found in the saliva. It has c y an S en - 
 been detected in this secretion in man (in whose saliva it 
 usually, but not invariably occurs), in the dog, and in the 
 sheep ; the evidence regarding its presence in the saliva of 
 the horse is contradictory, Lehmann having failed to detect 
 it. Its origin is, unquestionably, dependent on some special 
 decomposition of the tissues with which we are at present 
 unacquainted ; and the only suggestion regarding its use is 
 the very improbable one that it may check the formation of 
 minute fungi on the buccal mucous membrane (Kletzinsky). 
 
 END OF BOOK I. 
 
BOOK II. 
 
 THE 
 
 CHEMISTRY OF THE ANIMAL JUICES AND TISSUES, 
 
DIVISION OF THE SUBJECT. 143 
 
 BOOK II. 
 
 (134.) THE leading fluids or juices of the animal body Classlfica- 
 admit of a natural division or classification into the five subject.* C 
 following groups : 
 
 I. The digestive fluids, including the saliva, gastric juice, 
 bile, pancreatic fluid, and intestinal juice ; and to 
 these we have added the consideration of the intestinal 
 contents. 
 
 II. The blood and its allies, including the chyle, the lymph, 
 the blood itself, and the various transudations. 
 
 III. The fluids connected with generation and development, 
 
 including the seminal fluid, the milk, and the fluids of 
 the egg. 
 
 IV. The excretions of the mucous membrane and the skin, 
 
 including mucus, the various sebaceous matters, and 
 the sweat. 
 
 V. The urine. 
 
 After the consideration of these normally existing fluids we 
 shall notice those Exudations which are occasionally found, as 
 products of disease, in the animal organism, and shall con- 
 clude this Book with a few remarks on the Chemistry of the 
 Solid Tissues of the Body. 
 
144 PHYSIOLOGICAL CHEMISTRY 
 
 CHAPTER X. 
 
 THE DIGESTIVE FLUIDS. 
 SECTION I. THE SALIYA. 
 
 Saliva. (135.) THE saliva, in the ordinary acceptation of the term, 
 
 is a mixture of the secretions of the three pairs of salivary 
 glands and of the buccal mucus. It is a colourless, or very 
 faintly blue, turbid, viscid, inodorous, and tasteless fluid, 
 which, after standing for some time, separates into an upper 
 transparent layer, and a lower, opaque, yellowish-white por- 
 tion, consisting of pavement epithelium and mucus-corpuscles. 
 In the normal state its reaction is always alkaline, but the 
 degree of alkalinity varies, and is found to increase during 
 and after meals ; while after prolonged fasting the secretion 
 is almost neutral. The specific gravity of human saliva was 
 determined by Jacubowitsch at 1*0026, and, after the deposi- 
 tion of the sediment, at 1*0023. Lehmann states that its 
 usual variations in man are between 1*004 and 1*006, its 
 extreme normal limits being 1*002 and 1*009 ; while Wright, 
 our principal English experimenter on the saliva, asserts that 
 in numerous experiments made on two hundred healthy 
 persons, the specific gravity varied from 1*0069 to 1*0089. 
 Lehmann may be regarded as giving the safest estimate. 
 
 We shall now consider, individually, the various secretions 
 which collectively form the mixed saliva. 
 
 Parotid sa- (136.) The parotid saliva, which can only be obtained from 
 artificial or spontaneous fistulous openings in Steno's duct, is 
 limpid and colourless, devoid of smell and taste, not viscid, 
 has a specific gravity varying from 1*0061 to 1*0088 in man 
 
THE SALIVA. 145 
 
 (Mitscherlich), from 1-004 to 1-007 in the dog (Schmidt), and 
 from 1-0051 to 1*0074 in the horse (Lehmann) ; and is dis- 
 tinctly alkaline in its reaction. 
 
 The following may be regarded as the normal constituents 
 of this secretion : 
 
 (a.) An organic matter, named ptyalin, very similar to, Ptyalin. 
 but not identical with albuminate of soda, and occurring 
 in combination with potash, soda, and lime. It is a gela- 
 tinous matter, which is soluble in water, especially when 
 in combination with an alkali, and does not coagulate on 
 heating. That portion of it which is combined with lime is 
 soon displaced by carbonic acid, and the originally limpid 
 secretion becomes turbid on exposure to the air in the same 
 manner as lime-water. With this there is associated another 
 organic matter, which merely differs from it in not being pre- 
 cipitable by alum, and which has received no special name. 
 
 (.) A potash-salt of the volatile acids belonging to the 
 butyric-acid group, probably caproic acid. It crystallises in 
 beautiful tufts like margaric acid. 
 
 (c.) Sulphocyanide of potassium has been found in the 
 parotid saliva of man and various of the domestic mammals. 
 
 (d.) In the ash there are found considerable quantities of 
 the chlorides of sodium and potassium, some carbonate of 
 lime, and small quantities of phosphates. 
 
 In 1000 parts of the parotid saliva of a dog, Schmidt 
 found: 
 
 Water '' r T/ / -T ^/^"'ir. ' 995-3 
 Solid residue . . . ,,.,,* 4-7 
 
 Organic matter 1*4 
 
 Alkaline chlorides and sulphocyanides 2-1 
 Carbonate of lime 1*2 
 
 In man the percentage of the solid constituents seems 
 higher than in the dog, Mitscherlich fixing it at from 
 
 L 
 
146 PHYSIOLOGICAL CHEMISTRY. 
 
 1-468 to 1'632, and van Setten at l-62 (which is three times 
 as high as in the dog). 
 
 Submaxil- The submaxillary saliva is a clear, colourless, very viscid 
 lary saliva, fluid? ^^out smell or taste ; in the dog (and this is the only 
 animal in which this secretion has been carefully examined) 
 the specific gravity was found to vary from 1-0026 to 1*0041 
 (Schmidt). Its reaction is less strongly alkaline than that of 
 the parotid ; and it contains the same constituents as the 
 latter (including sulphocyanide of potassium), but less lime in 
 combination with organic matter. 
 
 Schmidt has given the two following analyses of this secre- 
 tion in the dog : 
 
 (1.) (20 
 
 Water. . . . r , % ' .'996-04 991*45 
 Solid residue . . " . , ' . 3-96 8-55 
 
 Organic matter .... 1-51 2-89 
 
 Inorganic matters . ,. . 2*45 
 Chlorides of sodium and potassium . . 4*50 
 Carbonate and phosphate of lime 
 
 and phosphate of magnesia . . . 1*16 
 
 The great difference of the solid residue in these cases is 
 dependent on the fact that in the former 25*23 grammes of 
 saliva were secreted in one hour, while in the latter only 13*6 
 grammes were yielded in the same time ; so that the absolute 
 quantity of solid residue is nearly the same in both cases. 
 Hence we may infer, that when there is a great augmentation 
 of the secretion, it is due almost solely to an excess of water. 
 Sublingual The sublingual saliva has never been separately analysed ; 
 most of these observations having been made on dogs, which 
 do not possess sublingual glands.* Longet has recently shown 
 
 * This is the view generally held hy comparative anatomists. Bernard, 
 however, maintains that in dogs and other carnivora there is a sublingual 
 gland in close contact with, but distinct from the submaxillary gland. 
 
THE SALIVA. 147 
 
 that, like parotid and submaxillary saliva, it contains sulpho- 
 cyanogen. 
 
 (137.) The secretion of the buccal mucous membrane, mixed, Buccal 
 however, with the secretion of the orbital glands, has been 
 examined in dogs (by Jacubowitsch). It is a very tough and 
 viscid fluid, colourless, but turbid from the presence of 
 epithelial cells, and alkaline in its reaction. Its solid residue 
 amounts to about 1-g-, in which about '61 is inorganic matter. 
 
 (138.) After this sketch of the physical and chemical cha- 
 racters of the individual fluids which collectively form the 
 ordinary or mixed saliva, we have little to add to the 
 observations in 135. regarding its physical and chemical 
 characters. 
 
 In the following table we give the chemical composition of Composi- 
 healthy human saliva, as determined by Frerichs and Jacubo- mixed sa 
 witsch (under Schmidt's superintendence) : liva> 
 
 Frerichs. 
 
 Water . ... 994-10 
 
 Solid constituents . 5*90 
 
 Epithelium and mucus 2*13 
 
 Fat .... 0-07 
 
 Ptyalin with a little 
 
 alcohol extract . 1-41 
 Sulphocyanide of 
 
 potassium . . 0-10 
 
 Fixed salts 2-19 
 
 Jacubowitsch. 
 
 Water .... 995-16 
 
 Solid constituents . 4*84 
 
 Epithelium . . 1'62 
 
 Soluble organic 
 
 matter . . . 1*34 
 Sulphocyanide of 
 
 potassium . , O06 
 
 Fixed salts 1-82 
 
 The " soluble organic matter," in the second analysis, is 
 probably a mixture of ptyalin and of mucin, an ill-defined 
 soluble organic matter occurring in mucus; and the 1-82 
 parts of fixed salts consisted of phosphate of soda 0-94, 
 lime 0*03, magnesia 0*01, and the chlorides of sodium and 
 potassium 0-84. 
 
 The presence of Sulphocyanide of potassium is interesting, 
 insomuch as the saliva is the only fluid in which sulpho 
 
 L 2 
 
148 PHYSIOLOGICAL CHEMISTRY. 
 
 cyanogen seems normally to occur ; and it is evident, from the 
 above analyses, that even here it exists in only very small 
 quantity. Lehmann found it to vary in his own saliva from 
 0*0046 to 0-0089 per cent. Kletzinsky * has examined the 
 conditions under which this constituent occurs in augmented 
 or diminished quantity in the saliva, and he believes that its 
 use is to prevent fermentation and the development of 
 fungoid spores ; and Herapath f has shown that the amount 
 of sulphocyanogen in the saliva, even of the same individual, 
 is liable to great fluctuations. 
 
 It is worthy of notice that the two latest observers who 
 have taken up this subject, and whose researches were pub- 
 lished in 1855, arrived at entirely contradictory results. 
 Longet maintains that sulphocyanides are invariable con- 
 stituents of the secretions of all the salivary glands, while 
 Kolliker and H. Miiller failed in detecting any trace of them 
 in the parotid and submaxillary fluids of the dog. 
 
 Abnormal (139.) Various incidental J and abnormal constituents are 
 frequently to be detected in the saliva. Amongst the former 
 we may place iodine, bromine, and mercury, when these sub- 
 stances are used medicinally ; while, amongst the latter, we 
 may mention some of the constituents of the bile (including 
 cholesterin), sugar, and possibly albumen. 
 
 * Heller's Archiv f. Phys. u. Path. Chemie, 1853, p. 39. I have given his 
 principal conclusions in " The Chemistry of Digestion," in the British and 
 Foreign Medico-Chir. Rev., 1853, vol. xii. p. 168. 
 
 f His results are given in my " Keport on the Progress of Animal Chemistry 
 during the Years 1852-3-4," in the British and Foreign Medico-Chir. Kev., 
 1855, vol. xv. p. 549. 
 
 % By incidental constituents we mean those which owe their origin to an 
 introduction from without, while we confine the term abnormal to those matters 
 which are generated within the organism. Strictly speaking, the former are 
 included in the latter. 
 
 Bernard has shown that the salivary glands and other secreting surfaces 
 exercise an elective elimination on foreign materials introduced either directly or 
 by absorption into the blood. Thus, he detected iodide of potassium in the saliva, 
 pancreatic juice, and tears, in less than one minute ; but in the urine and bile, 
 not till an hour after their injection. Lactate of iron furnishes no iron to the 
 saliva, but when iodide of iron is administered both constituents can be 
 recognised in that secretion. 
 
THE SALIVA. 149 
 
 Acid saliva is occasionally observed ; it seems chiefly to 
 occur in cases of irritation of the prima3 vias and of diabetes 
 mellitus ; but we do not know on what the acid reaction 
 depends, and, indeed, our knowledge of the pathological con- 
 ditions of the saliva is extremely imperfect. 
 
 (140.) Salivary concretions must be included amongst the Salivary 
 morbid products of this secretion. They have been frequently 
 analysed, and are found to contain more carbonate of lime 
 than any other kind of concretion. In the following table, 
 which will give a fair idea of their quantitative composition, 
 the first three analyses were made by Wright, the fourth by 
 von Bibra, and the fifth by Lecanu : 
 
 (1.) (2.) (3.) (4.) (5.) 
 
 Carbonate of lime .81-3 79-4 80-7 13-9 20 
 
 Phosphate of lime . 4-1 5*0 4-2 38-2 75 
 
 Phosphate of magnesia 5*1 
 
 Soluble salts . 6-2 4-8 5 
 
 00. 1 
 
 Animal matter . . 7-1 8-5 of 
 
 Water and loss ... 1-3 2'3 1'7 6-3 
 
 100-0 100-0 100-0 100-0 100-0 
 
 (141.) The daily quantity of saliva secreted by an adult Q uan tity 
 man has been variously estimated (by Burdach, Valentin, * saliva " 
 Donne and Thomson) at from 210 to 390 grammes (or from 
 about 6-5 to 12 ounces). From the recent investigations of 
 Bidder and Schmidt it appears, however, that these estimates 
 are far too low, and that an adult man secretes, on an average, 
 1500 grammes or about 48 ounces daily. 
 
 All such determinations as these must, however, be re- 
 garded only as approximations to the truth, since the activity 
 of the salivary glands is dependent upon various influences 
 and conditions. Movement of the lower jaw increases the 
 flow of saliva; hence mastication, speaking, and singing, 
 augment the secretion. Acid, aromatic, and irritant sub- 
 
 L 3 
 
150 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 stances produce a similar effect. Dry and hard food causes 
 an abundant flow, while the use of moist and soft food is 
 accompanied by a scanty secretion. Thus it appears, from the 
 observations of Bernard and others on horses, that straw and 
 hay, as they pass down the ossophagus, are mixed with four 
 or five times their weight of saliva, while seeds abounding 
 in starch, as, for instance, oats, are mixed with not more than 
 one and a half times their weight of saliva ; and fresh green 
 fodder with only half its weight; while food, mixed with 
 water, seems to take up scarcely any saliva. Corresponding 
 observations have since been made on the ox by Colin. 
 
 Some very interesting experiments on the influence of the 
 period of secretion on the constitution of the saliva have been 
 made by Becher and Ludwig.* They found that the solid 
 residue of the saliva diminishes in proportion to the amount 
 which the gland has already yielded ; the organic constituents 
 sinking far more rapidly than the inorganic. 
 
 (142.) The functions of the saliva are partly of a mechanical 
 and partly of a chemical nature. 
 
 The mechanical uses of the saliva are almost too apparent to 
 require notice. It is obvious that the moistening of dry food, 
 by the process of insalivation, serves the double purpose of 
 adapting it for deglutition and of separating the particles and 
 thus allowing them to be more freely acted on by the other 
 digestive fluids. Bernard believes that the parotid and sub- 
 maxillary fluids discharge independent functions that the 
 parotid, by its thin fluid property, serves to moisten the food, 
 while the tough and viscid secretion of the submaxillary 
 glands is specially subservient to the sense of taste, and, at 
 the same time, lubricates the bolus, and thus facilitates deglu- 
 tition. Liebig has suggested that the saliva, from its ten- 
 dency to frothing, may be designed to convey air into the 
 stomach and intestines ; it would appear, however, from the 
 investigations of Wright, Valentin, and others, that the 
 presence of oxygen is not necessary for gastric digestion. 
 
THE SALIVA. 151 
 
 (143.) It is now almost universally admitted that the prin- Chemical 
 cipal use of the salivary secretion is to promote the conversion uses ' 
 of the amylaceous portion of the food into dextrine, sugar, and 
 lactic acid, and thus to promote its absorption. 
 
 The first point to be noticed is the time required for the 
 metamorphosis of starch by ordinary (or mixed) human 
 saliva. If we take a decoction of starch, prepared with dis- 
 tilled water and proved by Trommer's test to be free from 
 sugar, and if we mix it with an equal quantity of fresh saliva, 
 and agitate the mixture, it will instantly lose its viscid cha- 
 racter and become thin and watery ; and, on testing a small 
 quantity of it for starch, we find that iodine no longer induces 
 the well-known reaction, while, on the other hand, the rapid 
 reduction of oxide of copper (in Trommer's test) affords in- 
 disputable evidence of the presence of sugar. The almost 
 instantaneous induction of this action is a point which must 
 not be overlooked in considering the question, whether this is 
 a special property of the saliva, or whether it is shared by 
 other animal fluids. There can be no doubt, as will be pre- 
 sently shown, that in this respect the pancreatic and intestinal 
 juices exactly coincide with the saliva; but when we find 
 stress laid upon the circumstance that many other organic 
 substances as, for instance, nasal mucus, pieces of kidney, 
 putrefying serum, &c., produce similar changes in eight or 
 twelve hours at 100 or upwards, we must recollect that at 
 such a temperature, and after so long an interval, changes may 
 be spontaneously set up in a solution of starch. There are, 
 however, a number of animal substances which occasion the 
 appearance of sugar in a solution of starch in so short a 
 period as altogether to exclude, in such cases, the suspicion of 
 spontaneous metamorphosis ; but the action induced by the 
 saliva is incomparably more rapid even than that of any of 
 these substances.* 
 
 * I have given a list of these substances (from Bidder and Schmidt), in 
 "The Chemistry of Digestion," in the British and Foreign Medico-Chir. 
 Review, 1853, vol. xii. pp. 172, 173. 
 
 L 4 
 
152 PHYSIOLOGICAL CHEMISTRY. 
 
 The question regarding the part which the various secre- 
 tions, entering into the composition of the saliva, take in this 
 action is a comparatively recent one, and much light has been 
 thrown upon this subject by the investigations of Bernard, 
 Jacubowitsch, Bidder and Schmidt, and others. The first 
 step in this direction seems to have been made by Magendie 
 and Eayer, who ascertained that the parotid secretion of the 
 horse exerted no metamorphic action on starch ; and Bernard 
 has subsequently demonstrated the same thing with the 
 parotid, submaxillary, and sublingual secretions of the dog, 
 showing that these fluids, either separately or mixed, exert no 
 action on amylaceous matters. Hence Bernard concludes that 
 the conversion of starch into sugar depends solely upon the 
 secretion of the buccal mucous -membrane a view which is 
 supported by the circumstance that the fluid obtained by 
 macerating this membrane in water possesses, after filtration, 
 the power of effecting this change. Since, however, it might 
 be objected that some of the salivary secretion might adhere 
 to the buccal mucous membrane, Bidder and Schmidt tied 
 the salivary ducts of a dog, and a fortnight afterwards found 
 that neither the buccal mucus nor the aqueous extract of the 
 detached buccal mucous membrane exerted any marked 
 change on a solution of starch results by no means in 
 accordance with Bernard's views. As the accuracy of this 
 statement, as originally promulgated by their pupil, Jacubo- 
 witsch, was impugned by Frerichs, they instituted new 
 experiments, and obtained not only the pure secretions of the 
 parotid and submaxillary glands, but also the pure secretion 
 of the buccal mucous membrane of dogs. The secretions thus 
 obtained were individually mixed with a solution of starch 
 and exposed to a temperature of 104. In no case was sugar 
 detected sooner than in eight hours, and then only in mere 
 traces, and hence they consider it as unquestionably esta- 
 blished that the ferment, on which the conversion of starch 
 into sugar depends, is not contained in any single one of the 
 
THE SALIVA. 153 
 
 secretions by whose admixture the ordinary saliva is formed, 
 and that it has its source solely in the admixture of some or 
 all- of these secretions. 
 
 The next question is Are all the three secretions (those 
 of the parotids, the submaxillaries, and the buccal mucous 
 membranes, for that of the sublingual glands is neglected by 
 most of these observers as unworthy of notice) of equal im- 
 portance in producing the final result, or would the admixture 
 of two of these be sufficient ? Jacubowitsch performed some 
 admirable experiments which, in themselves, seem to answer 
 the question definitely, although, in one important point, they 
 have not been confirmed by the subsequent observations of 
 Bidder and Schmidt. He convinced himself, by preventing 
 the parotid and submaxillary fluids from entering into the 
 mouth of a dog, that the mere secretion of the mucous mem- 
 brane of the mouth (contrary to Bernard's assertion) was 
 unable to convert starch into sugar. But when he tied the 
 ducts of only a single pair of glands (either of the two 
 parotids or the two submaxillaries), and then, after the re- 
 covery of the dog, digested starch with the saliva that exuded 
 from its mouth, some of the starch was converted into sugar 
 in the course of five minutes. Starch was also quickly 
 changed when brought in contact with an artificial mixture of 
 either of the above-named glandular secretions and buccal 
 mucus ; while a mixture of the parotid and submaxillary 
 fluids, without any secretion from the mucous membrane, was 
 entirely deficient in this property. The only point in which 
 Bidder and Schmidt, in their subsequent experiments, differ 
 from Jacubowitsch, is that, according to them, parotid saliva 
 mixed with pure buccal mucus exerts no marked action on the 
 conversion of starch into sugar. They are unable to account 
 for this difference in any satisfactory manner. They found 
 that a mixture of the secretion of the submaxillary glands 
 with pure buccal mucus exerted as rapid and perfect a meta- 
 morphosis of starch as the ordinary saliva. 
 
154 PHYSIOLOGICAL CHEMISTRY. 
 
 The following are the two principal conclusions at which 
 Bidder and Schmidt have arrived in connection with this 
 point : 
 
 1. They agree with Bernard in regarding the parotids as 
 glandes aquipares ; in short, as yielding a secretion which is 
 unquestionably intended to moisten and saturate the dry food, 
 but they believe that its principal object is connected with 
 the general metamorphosis of the fluids within the body. 
 
 2. They consider that the peculiar ferment which almost 
 instantly converts starch into sugar is formed by the union of 
 the submaxillary secretion and that of the buccal mucous 
 membrane, the parotid secretion taking no part whatever in 
 this process. This active principle is not contained in the 
 cells or other solid particles suspended in the saliva ; for the 
 filtered fluid exhibits an undiminished force, and, indeed, this 
 property is not destroyed when, by the addition of a little 
 alcohol, we precipitate the mucus and (entangled with it) 
 these solid particles. 
 
 Salivary (144-) Another subject examined by Bidder and Schmidt 
 
 hi^nfancy * s * ne condition of the salivary secretion during the period 
 when the infant or the young animal continues sucking. 
 Although, to all appearance, there is no special retardation of 
 the development of the tissues of these glands, yet at this 
 time they yield scarcely any secretion. This was de- 
 monstrated in the following ways: (1.) On establishing 
 fistulous openings in connection with Steno's duct in calves, 
 no fluid escaped through the canula. (2.) Starch was con- 
 verted into sugar in the presence of portions of the parotid or 
 submaxillary glands of adult animals in a far shorter period 
 than when the corresponding parts of sucking animals were 
 used. And (3.) when the saliva of an adult man and the 
 fluid from the mouth of an infant were, mixed with equal 
 parts of a thick solution of starch, the metamorphic action 
 commenced in equally short spaces of time, that is to say, 
 almost instantly in both cases ; but, in the former case, the 
 
THE SALIVA. 155 
 
 action was completed almost as soon as it was begun, while, in 
 the latter, the process occupied fully an hour. 
 
 (145.) Formerly much importance was attached to the Action 
 alkalinity of the saliva (which, by the way, seems rather to be n t e iva 
 due to the presence of an alkaline phosphate of soda than to 
 that of a free alkali), and it was regarded as an established fact, 
 that the special functions of this secretion must be altogether 
 suspended when it entered the stomach and was mixed with 
 the acid gastric juice. Although it seems universally admitted 
 that the addition of acid gastric juice to the saliva in sufficient 
 quantity to make the mixture acid has little or no effect 
 on the metamorphic action on starch out of the body, there is 
 still considerable doubt whether the action of the saliva on 
 starch is continued in the stomach. 
 
 Jacubowitsch relates that he made the following mixtures 
 and treated them with a fresh decoction of starch : 
 
 (a.) Pure filtered gastric juice (obtained from a dog with a 
 gastric fistula) was neutralised by human saliva; (6.) in 
 another instance it was rendered alkaline by an excess of 
 saliva ; (c.) in a third case it was rendered alkaline by soda ; 
 (d.) saliva was rendered acid by gastric juice; (<?.) pure 
 gastric juice was finally mixed with starch. 
 
 These mixtures were kept at a temperature varying from 
 86 to 104; and all of them, excepting c. and e., exhibited 
 distinct traces of sugar in the course of fifteen minutes. 
 
 These experiments show, as Jacubowitsch observes, that the 
 gastric juice does not in itself impede the metamorphic action 
 of saliva on starch ; and further that the former secretion, 
 even when neutralised with an alkali, possesses no such pro- 
 perty. Bidder and Schmidt speak quite as decisively. " New 
 experiments (they observe) have convinced us that the meta- 
 morphic action of the saliva in the presence of free acids 
 exhibits itself with quite the ordinary rapidity. We have 
 added to fresh human saliva enough acid gastric juice ob- 
 tained from dogs, or enough hydrochloric acid, to render the 
 
156 PHYSIOLOGICAL CHEMISTRY. 
 
 mixture neutral or acid, and have found that this mixture 
 caused as immediate a conversion of starch into sugar as 
 when pure alkaline saliva had alone been added." 
 
 Now since the gastric fluid may be regarded as a natural 
 mixture of the swallowed alkaline saliva with the acid gastric 
 juice, in which, however, the acid character normally pre- 
 vails, it might be expected that it would exert the same 
 metamorphic action on starch as the artificially acidulated 
 saliva. This, however, is a warmly disputed point, Blondlot, 
 Bouchardat and Sandras, and Bidder and Schmidt, maintain- 
 ing, from their researches on the lower animals (dogs, sheep, 
 and rabbits), that no conversion of starch into sugar takes 
 place within the stomach ; while Frerichs, in at least fifty 
 experiments, constantly found sugar in the filtered contents 
 of the stomachs of men, carnivorous and omnivorous mam- 
 mals, and birds ; and von Schroder, by his observations on a 
 woman with a gastric fistula, seems to have established the 
 point (in so far as man is concerned) beyond all cavil. In 
 experiments out of the body, he found that the neutral or 
 alkaline saliva, containing gastric juice secreted in the fasting 
 state, very rapidly converted boiled starch into sugar, which 
 did not undergo a further change into lactic acid for many 
 hours. Shortly after a meal it often happened that no sugar 
 could be detected in the gastric contents, while sugar could 
 be easily recognised in the same mixture some hours after- 
 wards - a proof that even small quantities of saliva are not 
 impeded in their action on starch by the presence of the 
 gastric juice. Similar facts were observed within the body* 
 When boiled starch was introduced through the fistulous 
 opening into the stomach, it rapidly underwent a change 
 into sugar, while crude starch remained unchanged in the 
 stomach for an hour and a half.* 
 
 In all probability the conversion of starch into sugar con- 
 
 * Although Schroder has thus arrived at a conclusion apparently opposed 
 to the opinion of Bidder and Schmidt, it is but an act of justice to those most 
 admirable experimenters to state that he made similar observations on a dog 
 
THE SALIVA. 157 
 
 tinues in the stomach until some at present undetermined 
 degree of acidity is presented by the gastric contents. By 
 adopting this view the opposing views can be harmonised, and 
 in support of it may be adduced an experiment recently made 
 (1854) by Kolliker, who prepared a strong digestive fluid 
 from a pig's stomach and hydrochloric acid, and mixed it with 
 human saliva in different proportions. He found that on 
 taking equal quantities of the two fluids, the action on a solu- 
 tion of starch altogether disappeared ; that with one part of 
 gastric juice and two of saliva, sugar was found in twenty 
 minutes ; while with one part of the former to three or four 
 of the latter, sugar appeared in from five to ten minutes. 
 
 (146.) The saliva exerts no definite metamorphic action on 
 any of the carbo-hydrates, except starch; cane-sugar, gum, 
 vegetable mucus (bassorin), and cellulose, remain unchanged 
 in it ; nor does it exert any chemical action on the protein- 
 bodies or on gelatin, its utmost effect being to relax their 
 tissues like pure water, and thus to render them more 
 accessible to the action of the special secretion prepared for 
 their transformation, the gastric juice. 
 
 (147.) There is one additional point in connection with the Saliva in 
 chemistry of the saliva which should be noticed, namely, the 
 intensely poisonous character which it assumes in rabies. 
 Our knowledge on this point is altogether negative. That 
 the active agent in these cases is the sulphocyanide of potas- 
 sium, which is assumed to be increased in rabies, is improbable, 
 because this salt has been given to dogs in large doses without 
 producing any decided poisonous effects ; and, as it was redis- 
 covered in the urine, it must have passed unchanged through 
 the blood. An analysis of the secretions of the poison-glands 
 of some of the venomous serpents might possibly throw some 
 light on this subject. 
 
 with a gastric fistula, and, like them, he could find no sugar in the contents of 
 the stomach. This discrepancy is probably due to the fact that the action of 
 the dog's saliva on starch is much less rapid than that of human saliva, often 
 not showing itself for ten or fifteen hours. 
 
158 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Gastric 
 juice. 
 
 Mode of 
 
 obtaining 
 
 it. 
 
 Its physi- 
 cal and 
 chemical 
 characters. 
 
 SECTION II. THE GASTEIC JUICE. 
 
 (148.) The chemical and physiological characters of the 
 human gastric juice have been recently studied by Schmidt * 
 and two of his pupils, Gruenewaldt f and Schroeder, under 
 peculiar advantages. Their observations were conducted on 
 an Esthonian peasant, Catherine Kiitt, aged 35 years, and 
 weighing about 118 Ibs., in whom there had existed for three 
 years a gastric fistula, three or four lines in diameter, under 
 the left mammary gland, between the cartilages of the ninth 
 and tenth ribs. The introduction of dry pease and a little 
 water into the stomach throjigh the opening occasioned (even 
 in the morning, on an empty stomach) the secretion of from 
 five to seven ounces of a clear limpid fluid with an acid re- 
 action, which, however, was much less strong than Schmidt 
 had observed in previous experiments on the gastric juice of 
 dogs or sheep, in which he had established fistulous openings. 
 It flowed through an elastic tube that was inserted into the 
 fistula, sometimes in a thin stream, and sometimes in a rapid 
 succession of drops. 
 
 (149.) The acid and limpid fluid thus obtained was devoid 
 of odour, had a mawkish taste, became very slightly turbid on 
 the application of heat, and left, on evaporation, a yellowish 
 brown, very acid, deliquescent residue, which, on incineration, 
 yielded a colourless, neutral, or slight alkaline ash, that did 
 not effervesce on the addition of acids. The density of the 
 fluid varied from 1-0022 to 1-0024. 
 
 On examining the gastric juice under the microscope we 
 find that it presents few morphotic elements; those which 
 
 * Schmidt, Ueber die Constitution des menschlichen Magensaftes, in Ann. 
 d. Ch. u. Pharm., 1854, vol. xcii. p. 42. 
 
 f Gruenewaldt et Schroeder, Disquisitiones de Succo Gastrico Humano ope 
 fistulas stomachalis institute. Dorp. Liv. 1853. 
 
THE GASTRIC JUICE. 
 
 159 
 
 3-195 
 
 4-202 
 
 17-507 
 
 0-200 
 
 1-557 
 
 2-703 
 
 0-061 
 
 0-114 
 
 1-661 
 
 1-465 
 
 4-369 
 
 3-147 
 
 0-550 
 
 1-518 
 
 1-073 
 
 are present consist partly of cells from the gastric glands, 
 partly of their nuclei, and partly of finely comminuted mole- 
 cular matter. 
 
 The following table gives the mean of two analyses * of the 
 gastric juice of Catharine Kiitt, with corresponding mean 
 results of analyses of the same fluid in the sheep and the 
 
 dog: 
 
 Human 
 Gastric Juice. Sheep's do. Dog's do. 
 
 Water 994-404 986-147 971-171 
 
 Solid constituents . . 5-596 13-853 28-829 
 
 Ferment with a trace of 
 ammonia 
 
 Hydrochloric acid . 
 
 Chloride of calcium 
 
 Chloride of sodium 
 
 Chloride of potassium 
 
 Phosphates of lime, mag- 
 nesia, and iron . . 0-125 2-090 2-738 
 
 The fluid in the above analyses (all of which were made by 
 Schmidt) cannot be regarded as perfectly pure gastric juice, 
 because it contains the swallowed saliva. The chief effect of 
 this admixture seems to be to diminish the quantity of free 
 hydrochloric acid and to increase the phosphates, f 
 
 The gastric juice contains two essential elements a free Its esscn- 
 acid and a highly nitrogenous matter allied to the albumi- me nts. 
 
 * The analyses in this table were made by Schmidt himself with the gastric 
 juice obtained in the manner above indicated. They differ very considerably from 
 the analyses given in Gruenewaldt's Thesis (and which are to be found in my 
 Appendix to Lehmann's Physiological Chemistry, vol. iii. p. 504.), in conse- 
 quence of the different modes in which the fluids were obtained. In the 
 latter case, the analysed fluid was the filtered contents of the stomach, shortly 
 after a meal, which explains the large amount of solid residue. 
 
 t In corroboration of this statement, I may refer to the comparative analyses, 
 instituted by Schmidt, of the gastric juice of dogs in their ordinary state, and 
 with their salivary ducts tied. See " The Chemistry of Digestion," in the 
 British and Foreign Medico-Chir. Kcv., 1853, vol. xii. p. 184, 
 
160 PHYSIOLOGICAL CHEMISTRY. 
 
 nates commonly known as pepsin, but to which Schmidt and his 
 school have given the name of ferment substance. There is 
 a great diversity of opinion regarding Loth these substances, 
 and I shall briefly notice the most important views that have 
 been brought forward regarding them. 
 
 (150.) Prout (in 1824) maintained that the free acid of the 
 gastric juice was hydrochloric acid, and Tiedemann and 
 G-melin, and several other writers, have adopted his view. 
 Lehmann, on the other hand, asserts that lactic acid (either 
 alone or associated with hydrochloric acid) is the main acidi- 
 fying agent, and his experiments have been repeated and 
 distinctly confirmed by Heintz, and are more or less supported 
 by the observations of Bernard and Barreswil, Pelouze, R. D. 
 Thomson, and others.* Blondlot again maintains that the acid 
 reaction of the gastric juice is solely due to the presence of 
 acid phosphate of lime an opinion utterly at variance with 
 the results obtained by all trustworthy chemists, and not 
 deserving further notice. The most correct view seems to be 
 that hydrochloric acid is always present, commonly but not 
 always associated with lactic acid. In the gastric juice of the 
 woman above referred to, Schmidt, in one analysis, found 
 0-022, and in another 0-018^- of free hydrochloric acid and no 
 lactic acid ; while, in six analyses of the gastric juice of dogs, 
 Lehmann found the free hydrochloric acid to range from 
 0-098 to 0-132, and the free lactic acid from 0-320 to 
 
 When gastric juice is obtained for examination shortly 
 after food has been taken, it is generally found to contain no 
 free hydrochloric acid, but other free acids derived from the 
 
 * Alexis St. Martin, whose name is indelibly connected with the physiology 
 of digestion through Dr. Beaumont's experiments, has again (1856) sub- 
 mitted himself to scientific observation. The acidity of his gastric juice has 
 been studied by Professor R. E. Rogers, who finds that the main agent in pro- 
 ducing the acid reaction is lactic acid, and that if hydrochloric acid be pre- 
 sent, it is only in very small quantity. 
 
THE GASTRIC JUICE. 161 
 
 decomposition of the food, especially lactic and butyric 
 acids. 
 
 (151.) Our knowledge of pepsin is still very imperfect. It Pepsin, 
 is closely allied to the protein-bodies, does not coagulate when 
 heated, but is deprived by that process of its characteristic 
 property of dissolving the protein-bodies and of converting 
 them into the non-coagulable substances, to which Lehmann 
 has given the name of peptones. It is precipitated by cor- 
 rosive sublimate, the salts of lead, alcohol, and tannic acid. 
 It may be separated from the mercury and lead compounds 
 by sulphuretted hydrogen, and, on the addition of a few drops 
 of dilute hydrochloric acid, possesses a great solvent power 
 over coagulated albumen. Schmidt, some years ago, suggested 
 and still adheres to the view that the active principle of the 
 gastric juice should be regarded as a compound of pepsin (or 
 as he terms it, ferment or ferment-substance) and hydrochloric 
 acid in short, as a conjugated acid whose negative con- 
 stituent is hydrochloric acid with coagulated pepsin as an 
 adjunct. He regards it as more nearly resembling ligno- 
 sulphuric acid than any other conjugated acid, and as this 
 becomes disintegrated into dextrine and sulphuric acid, so the 
 pepsin-hydrochloric acid becomes separated at 212 into co- 
 agulated pepsin and hydrochloric acid ; and in either case it 
 is equally impossible to reproduce the compound from the 
 separated proximate principles. It is unnecessary to enter 
 further into this view because, ingenious as it is, and singularly 
 as it seems to harmonise with certain facts, there are other 
 and very important facts which render its correctness doubtful. 
 Thus, for instance, the existence of the pepsin-hydrochloric 
 acid has not been established by any analysis of a combination of 
 it with a mineral base or with an albuminous substance ; and 
 Lehmann, who has instituted numerous experiments regarding 
 the quantitative relations between the digestive fluid and the 
 substances to be digested, states that he cannot ascertain that 
 there are any such proportions between the acid and the 
 
 M 
 
162 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 digested substance as at all accord with the ordinary acid 
 or basic combinations of acid and base. 
 
 Besides pepsin, the gastric juice contains another more soluble 
 organic matter, which has not been accurately studied. 
 
 (152.) The mineral constituents of the gastric juice consist 
 chiefly of chlorides, as may be seen by a glance at the analyses 
 in page 159. In addition to an abundance of chloride of 
 sodium we have smaller quantities of the chlorides of 
 ammonium, calcium, and magnesium, with traces of the 
 phosphates of lime, magnesia, and iron. 
 
 (153.) Very little is known regarding the abnormal con- 
 stituents which, under certain conditions, may occur in the 
 gastric juice. In gastric catarrh we may have an excess of 
 mucus, which sometimes, even while in the stomach, may 
 undergo decomposition, and, on coming in contact with 
 amylaceous or saccharine food, may establish acetic, butyric, 
 or lactic fermentation, in which case the contents of the 
 stomach contain far more free acid than occurs in them in 
 normal digestion. Urea has often been found in vomited 
 matters in cases of ursemia, consequent on Bright's disease or 
 on cholera. Lehmann, however, states that in these cases he 
 has always found the contents of the stomach and the vomited 
 matters strongly alkaline and always rich in carbonate of 
 ammonia, but never containing urea. 
 
 (154.) The quantity of gastric juice secreted in twenty-four 
 hours was determined by Bidder and Schmidt in the case of 
 sheep to be one-eighth, and in that of dogs to be about one- 
 tenth of the whole weight of the body. Assuming the latter 
 ratio to be true for men, a man of ordinary weight, say of ten 
 stone, would secrete about fourteen pounds of this fluid. In 
 the case of Catherine Kiitt the mean daily quantity amounted 
 to no less than fourteen kilogrammes, or about thirty-one 
 pounds, that is to say, to more than a fourth part of the 
 weight of the body. On this calculation a man of ten stone 
 would daily secrete thirty-seven pounds of gastric juice. As 
 
THE GASTRIC JUICE. 163 
 
 might naturally be expected, the quantity and the density of 
 the gastric juice in these cases stand in an inverse ratio to 
 one another. , 
 
 (155.) There is no ambiguity regarding the function of the its func- 
 gastric juice. It serves not only to dissolve but also to modify t[on ' 
 the nitrogenous elements of the food (the protein-compounds 
 and their derivatives), converting them into thoroughly new 
 substances (peptones), which, although they coincide in their 
 chemical composition and in many of their physical properties 
 with the substances from which they are derived, essentially 
 differ from them, not only in their ready solubility in water 
 and even in dilute spirit, but in having now lost the faculty 
 of forming insoluble combinations with most metallic salts. 
 The formation of these peptones depends solely on the action 
 of the gastric juice, and occurs without the evolution or 
 absorption of any gas, and without the production of any 
 secondary substance. 
 
 This power is suspended by boiling the gastric juice, by 
 saturating its free acid with an alkali, by sulphurous and 
 arsenious acids, by alum, and by most metallic salts ; and it 
 is very much impeded by the addition of alkali-salts, and by 
 saturating the fluid with soluble organic compounds. The 
 addition of water to a gastric juice which has been already 
 saturated by a peptone, enables it to resume its digestive 
 powers, which are also restored, to a certain degree, by the 
 addition of free lactic or hydrochloric acid. 
 
 Fats, when added in certain quantity to the gastric juice, 
 promote the conversion of the protein-bodies into peptones. 
 
 Bidder and Schmidt found, in the course of their numerous 
 experiments, that gastric juice mixed with saliva had a less 
 energetic digestive power than pure gastric juice obtained from 
 animals whose^ salivary ducts were tied a fact obviously 
 dependent on a portion of the free acid being saturated by 
 the alkaline saliva. They likewise found that the addition of 
 bile to the gastric juice entirely suspended its solvent action ; 
 
 M 2 
 
164 PHYSIOLOGICAL CHEMISTRY. 
 
 although the mixture still remained decidedly acid. The 
 latter fact demonstrates that, when undigested albuminous 
 matters pass into the intestine, the gastric juice must lose all 
 power over them. 
 
 According to Lehmann's experiments, 100 grammes of 
 fresh gastric juice are capable of dissolving 5 grammes of 
 coagulated albumen.* 
 
 All our best observers agree that the gastric juice exerts no' 
 apparent action on the non-nitrogenous articles of food, 
 namely, the fats and carbohydrates, f As the fats unquestion- 
 ably exert a favourable influence on the digestion of nitro- 
 genous matters, it is probable that they undergo some slight 
 change, but the quantity of fatty matter which is modified 
 during the digestive process is. so minute as not to be appre- 
 ciable by analysis. Starch, gum, and sugar, when placed in 
 pure gastric juice at the temperature of the animal body, do 
 not undergo any change corresponding to true digestion. 
 
 (156.) Although the main object of the gastric juice is to 
 dissolve the protein-bodies, it does not suffice to dissolve the 
 quantity necessary for the proper nutrition of the organism. 
 Since a dog secretes about 100 grammes of gastric juice for 
 every 1000 grammes of its bodily weight (10-g-), & would only be 
 
 * Schmidt, who instituted numerous experiments of a similar kind, arrived at 
 a far lower result. He found that on an average 100 grammes of the gastric 
 juice of the dog dissolved only 2'2 grammes of coagulated albumen rather 
 less than half the quantity obtained by Lehmann. It is probable that the 
 higher mimber obtained by the last-named chemist was due to the presence of 
 lactic acid which did not exist in the gastric juice used by Schmidt. Since 
 many conditions favouring digestion co-operate within the stomach, and since 
 the gastric juice obtained from dogs with fistulous openings may possess less 
 digestive power than that which is secreted from uninjured stomachs, Schmidt 
 believes that the gastric juice may be able to dissolve a larger amount of 
 ftlbuminous matter than these results would seem to indicate. 
 
 f Professor R. E. Eogers, of the Pennsylvania University, who has been 
 recently (1856) examining the chemical relations of the gastric juice obtained 
 from Alexis St. Martin, arrives, however, at the startling conclusion, that " the 
 conversion of starch into grape-sugar may take place in the stomach indepen- 
 dently of the action of saliva " ! 
 
THE GASTRIC JUICE. 165 
 
 able (taking Lehmann's estimate, which is more than twice as 
 high as Schmidt's) to digest 5 grammes of dry or coagulated 
 albumen for that amount of weight ; but a dog, in order to 
 keep in condition on an exclusive flesh-diet, (and this is its 
 natural food,) should take 50 grammes of flesh, containing 10 
 grammes of dry albuminates, for every 1000 grammes of 
 weight. Hence its gastric juice only suffices for the digestion 
 of half the albuminates necessary for its nutrition a result 
 which will be fully explained when we treat of the intestinal 
 juice, and which is quite in accordance with the observed 
 fact, that a considerable portion of the albuminates enters 
 the small intestine in an undissolved state. On comparing 
 the experiments made by Hubbenet on dogs with those made 
 by Schroeder on Catherine Ktitt, we have evidence that in 
 man the gastric digestion of the albuminates must be more 
 imperfect than even in the dog; for, while in the latter 46'8-g- 
 and 77'1-g- of coagulated albumen were dissolved in four and 
 six hours respectively, only 23'6 and 39'1-g- were dissolved in 
 five and eight hours respectively in the human stomach : and 
 similarly, raw flesh introduced in small muslin bags into the 
 human stomach did not become entirely dissolved for nineteen 
 or twenty hours, while in the dog the same process did not 
 occupy more than from two and a half to four hours. 
 
 (157.) The vitality of the stomach has been usually assigned Why the 
 as the reason why it is not digested by its own secretion. j s not 
 Eecent observations of Bernard*, confirmed in this country by di s ested - 
 Dr. Pavy, show, however, that mere vital force can offer no 
 available resistance to the chemical force of the gastric juice. 
 On inserting the hind legs of a live frog into a dog's stomach, 
 through a fistulous opening, the flesh of the extremities is 
 almost as rapidly dissolved as if it did not belong to a living 
 animal. The resisting power of the stomach seems due to 
 the continuous re-formation of epithelium during the process 
 of digestion. 
 
 * Le9ons de Physiologic Experimentale, 1856, vol. 2. p. 408. 
 M 3 
 
166 PHYSIOLOGICAL CHEMISTRY. 
 
 SECTION III. THE BILE. 
 
 (158.) The bile of most mammals, as obtained from the 
 gall-bladder, presents the following properties in common. 
 It is a viscid and tenacious fluid of a green or brown colour, 
 with a bitter taste and (especially on the application of 
 warmth) a peculiar and often musk-like odour. Its specific 
 gravity is about 1'020; it is usually faintly alkaline, but 
 often perfectly neutral. Bile in its ordinary state putrefies 
 very readily, but after it is freed from mucus, it altogether 
 ceases to exhibit that tendency. 
 
 Fresh human bile can only be obtained from the bodies of 
 criminals who have been executed, and has been very rarely 
 examined. Most of our knowledge regarding the biliary 
 secretion and the influence of bile on the digestive system 
 has been derived from observations on animals, in which the 
 bile-ducts were tied and biliary fistulse had been established. 
 
 (159.) The bile, in the case of all animals, contains two 
 essential constituents, one of which is of a resinous nature 
 while the other is a pigment. 
 
 The resinous constituent is not precisely identical in all 
 kinds of bile ; it generally consists of a soda-salt whose acid 
 is one of the conjugated acids, with glycine or taurine as its 
 adjunct, described in pp. 60-61. Strecker, to whom we are 
 mainly indebted for our knowledge of the chemistry of the 
 bile, states that in most mammals the resinous constituent 
 merely differs in the varying proportions in which the tauro- 
 cholates and glycocholates are intermixed, the taurocholates 
 usually preponderating. The bile of the dog consists almost 
 exclusively of taurocholate of soda. The bile of the pig pre- 
 sents certain chemical peculiarities, one of which is noticed 
 in 53. 
 
 The only bird whose bile has yet been analysed is the 
 
THE BILE. 167 
 
 goose. Taurocholates are present in the secretion to the 
 almost entire exclusion of glycocholates. 
 
 The same is the case with the bile of fishes (the cod, pike, 
 &c.), in which the resinous constituent consists of taurocho- 
 lates, with mere traces of glycocholates. It is worthy of 
 notice that, contrary to what might have been expected, 
 potash-salts preponderate in the bile of sea fishes, and soda- 
 salts in that of fresh- water fishes. 
 
 In most kinds of bile the resinous constituent amounts, 
 according to Lehmann*, to at least 75-- of the solid residue, 
 but this seems too high an estimate. 
 
 The bile-pigment occurs in the bile of different animals Bile pig- 
 under two forms, namely, as a brown and as a green pigment, 
 the latter most probably, however, being a product of the 
 oxidation of the former. The normal quantity of pigment in 
 the bile has not been determined. 
 
 Another constituent that is invariably present in the bile is Choles- 
 cholesterin, which is probably held in solution by the tauro- 
 cholate of soda, since it very rarely occurs in the bile in a 
 crystalline form. It occurs in extremely small quantity. 
 
 Free fats, which are also held in solution by the taurocho- 
 late of soda, and saponified fats, are ordinary constituents of 
 bile, and with the cholesterin formed, in Grorup-Besanez's two 
 cases, 27 and 30^- of the solid residue. 
 
 As the taurocholic and glycocholic acids, the fatty acids ? 
 and, as we shall presently see, the pigment, are combined with 
 alkalies or alkaline earths, it is obvious that the process of 
 incineration will completely modify all pre-existing relations 
 amongst the inorganic constituents. The only trustworthy 
 analysis of the mineral constituents of the bile is that of 
 
 * Lehmann deduces this number from a knowledge of the quantity of sulphur 
 in the bile, as determined by Strecker, Bensch, and others. All the sulphur is 
 contained in the taurine, and every 100 parts of taurocholate of soda contain 
 6 of sulphur. The numbers actually obtained by Gorup-Besanez from the bile 
 of two criminals immediately after their execution were considerably lower, 
 namely 55*4 and 60*8g. 
 
 M 4 
 
168 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Amount of 
 solid con- 
 stituents. 
 
 Difference 
 between 
 cystic and 
 hepatic 
 bile. 
 
 Weidenbusch *, who found in ox-bile chloride of sodium in 
 large quantity (2 7 ?--), tribasic phosphates of soda and potash, 
 carbonate of soda, phosphates of lime and magnesia, and small 
 quantities of iron, manganese, and silica. 
 
 Finally, the bile always contains a certain amount of mucus 
 secreted by the lining membrane of the gall-bladder. It is 
 to this constituent that the bile mainly owes its viscid pro- 
 perty. The cylinder epithelium contained in this mucus is 
 the only morphotic element in fresh normal bile. 
 
 Human bile contains, according to Frerichs, 14-g- (or rather 
 less) of solid constituents, w.hile in the two cases analysed by 
 Grorup-Besanez, it yielded 10-19 and 17'73-g- respectively. The 
 bile of the ox yields from 10 to 13, and that of the pig from 
 10-6 to 11-8%. 
 
 The organic constituents of human bile collectively amount 
 to about 90^, Frerichs fixing them at 87, and Grorup-Besanez 
 at 93*6^-, while the organic constituents of the bile of most 
 mammals are rather less abundant, namely about 87-g-. 
 
 (160.) We are indebted to the researches of Bidder and 
 Schmidt for almost all the knowledge we possess regarding 
 the differences between fresh hepatic and cystic bile. The 
 fresh bile of carnivorous animals (dogs, cats, crows) is yellow 
 or yellowish brown, while that of herbivorous animals (rab- 
 bits, sheep, geese) is green. The colour of cystic bile in the 
 former class of animals, is for about three hours after a meal 
 as yellow as the hepatic bile, but it then becomes greenish, 
 and if no food has been taken for twenty hours it assumes a 
 deep green tint. As hepatic bile gradually becomes green on 
 exposure to the atmosphere, and as, further, the yellow tint 
 re-appears on the application of deoxidising agents, we cannot 
 entertain a doubt that this change of colour is dependent on 
 an oxidation effected by the arterial blood in the capillaries 
 of the inner coat of the gall-bladder 
 
 * Pogg. Ann. 1849, vol. 76. p. 386. 
 
THE BILE. 169 
 
 Prolonged retention of the bile in the gall-bladder gives 
 rise to a very decided concentration of that fluid. Thus, 
 while the fresh hepatic bile of dogs and cats contains, on an 
 average, 5-g- of solid constituents, the cystic bile may contain 
 from 10 to 20-g-, according to the length of its retention; and 
 while the fresh bile of the rabbit contains only 2-g-, the cystic 
 bile may yield as much as 15. The bile of the goose and of 
 the crow yielded similar results. 
 
 (161.) The most important abnormal constituents of the Abnormal 
 bile are albumen and urea. The former has been observed in tuents. 
 cases of fatty liver and of Bright's disease, while the latter 
 has been found in cases of uraemia, as, for instance, in Bright's 
 disease and cholera a result quite in accordance with 
 an observation that had been previously made, namely, 
 that urea occurs in the bile after the extirpation of the 
 kidneys. 
 
 Bile which, in consequence of disease, has been retained 
 for a long time in the gall-bladder, occasionally presents a 
 sediment which, when examined under the microscope, is 
 found to consist of greenish or brownish rod-like molecules, 
 or of crystals arranged in rows. The term bilifulvin has been 
 applied by Virchow to the substance forming these sediments, 
 and we occasionally find intermingled with these molecules 
 those crystals of hsematoidin which are also found in old 
 extravasated blood. 
 
 We possess very little accurate knowledge regarding the 
 changes which the bile undergoes in disease. It appears to 
 be abnormally watery after severe inflammations, especially 
 in cases of death from pneumonia; and a similar change 
 seems to be impressed upon it by dropsies, diabetes, typhus, 
 and occasionally by tuberculosis ; while there is an excess of 
 solid constituents in diseases impeding the venous circulation 
 in the abdomen, and in cholera. The mucus is sometimes 
 extraordinarily increased, especially in cases of typhus. 
 
 (162.) In connection with the morbid conditions of the Gall- 
 stones. 
 
170 PHYSIOLOGICAL CHEMISTRY. 
 
 biliary secretion we must notice gall-stones* There are 
 several varieties of these concretions. We may have a 
 nucleus consisting of a chemical compound of pigment and 
 lime, pigment-lime as it may be termed for brevity (first 
 described and shown to be a frequent cause of the formation 
 of gall-stones by Bransom) f , while the bulk of the stone is 
 made up of cholesterin ; or the pigment-lime and cholesterin 
 may be more uniformly diffused through the concretion ; or 
 if the gall-stone be of a blackish or dark green colour it 
 probably consists of the pigment in a modified state, but still 
 in combination with lime : in such concretions as these there 
 is usually little or no cholesterin. 
 
 Biliary concretions in which carbonate and phosphate of 
 lime are the chief ingredients are very rare. 
 
 (163.) We have never had an opportunity of directly 
 observing the quantity of bile that is secreted in the human 
 subject, and it is extremely improbable that we shall ever 
 have a case presenting tne two conditions of a thoroughly 
 closed ductus communis and a fistulous opening connected with 
 the gall-bladder. All our information on the amount of the 
 daily secretion of bile is derived from observations on animals 
 in which these conditions have been artificially induced. 
 
 Bidder and Schmidt J found from numerous experiments 
 and observations that there was secreted, for 1000 grammes' 
 weight of the animal, 
 
 In the Cat. 
 
 Dog. 
 
 Sheep. 
 
 Eabbit. 
 
 Goose. 
 
 Crow. 
 
 Fresh bile . . . 14-500 
 
 19-990 
 
 25-416 
 
 136-84 
 
 11784 
 
 72-096 
 
 Solid constituents . 0-816 
 
 0-988 
 
 1-344 
 
 2-47 
 
 0-816 
 
 5-256 
 
 * The general history of gall-stones is very ably discussed in Vogel's 
 "Pathological Anatomy of the Human Body," 1847, pp. 369 375. On this 
 subject, and, indeed, on animal concretions generally, I may refer the reader to 
 a recent work by von Hemsbach (published after his death by Billroth) entitled 
 " Mikrogeologie. Ueber die Concremente im thierischen Organismus." 
 Berlin, 1856. 
 
 f Zeitschr f. rat. Med. 1846, vol. 4. pp. 193208. 
 
 j Op. cit. 
 
THE BILE. 171 
 
 Similar observations have been subsequently made on the 
 dog by Nasse, Arnold, and Kolliker and Miiller.* The last 
 named physiologists have arranged in a tabular form the 
 results of all the observations made on the daily amount of 
 bile secreted by the dog. The conclusion at which they 
 arrive from their own experiments is that a dog for 1000 
 grammes' weight secretes daily 36*1 grammes of bile contain- 
 ing T162 grammes of solid residue. If the same proportion 
 holds good for the human species, a man weighing ten stone 
 would daily secrete 2310 grammes or about five pounds of 
 bile. 
 
 (164.) Although there is a continuous secretion of bile, equal Agents in 
 quantities are not secreted in equal times. The experiments 
 instituted during the last few years by Bidder and Schmidt, tif J 
 Arnold, and Kolliker and Miiller, show that the flow of bile 
 is considerably modified by the digestive process. Their 
 results are, however, somewhat discordant. According to 
 Bidder and Schmidt the secretion (in dogs) is most abundant 
 in from thirteen to fifteen hours after feeding, while Arnold 
 found that the secretion was most copious at a more early 
 period and that it began to decrease from the fourth hour. 
 Kolliker and Miiller find that in the first and second hour 
 after a meal very little bile is secreted less even than in 
 the nineteenth and subsequent hours. In the third, fourth, 
 and fifth hours there was, with scarcely an exception, an 
 augmentation of the secretion ; indeed, in a few cases it 
 reached its maximum in the fifth hour, while in all the others 
 this was attained in the sixth, seventh, or eighth hour, after 
 which the quantity gradually diminished, but the minimum 
 was reached in from the nineteenth to the twenty-fifth hour. 
 There seems reason for believing that the period at which the 
 maximum secretion takes place is dependent on the amount 
 of the meal. After a moderate meal it occurred between the 
 
 * Verhandl. d. phys.-med. Gesellsch. in Wurzburg, 1856, vol. 7. p. 464. 
 
172 PHYSIOLOGICAL CHEMISTRY. 
 
 fifth and eighth hours, as in Kolliker and Miiller's observations, 
 while after a very copious repast it is retarded, as in Bidder 
 and Schmidt's experiments. This is Kolliker's explanation, 
 and some of his own facts are confirmatory of its accuracy. 
 
 Bidder and Schmidt have ascertained that when animals 
 are deprived of food for a longer period than twenty-four 
 hours (as, for instance, two, three, seven, or ten days) the 
 biliary secretion continuously decreases. Thus, for instance, 
 in cats the quantity of bile secreted on the tenth day did not 
 exceed the fourth part of what they secreted during the 
 twenty-four hours immediately succeeding a meal. 
 
 All observers concur in the view that the amount of the 
 biliary secretion varies directly with the quantity of the food ; 
 and as animals with biliary fistulse usually have voracious 
 appetites, experiments on this point are easily made. Kolliker 
 and Miiller found that on increasing a dog's food 56-g- they 
 caused an augmentation of the bile amounting to 58-g-, and 
 its collective solid constituents were increased in a similar 
 ratio. 
 
 Moreover, the nature pf the food probably exerts a certain 
 influence on the amount of the biliary secretion. A flesh- 
 diet appears, according to numerous experiments, to cause a 
 more abundant secretion of bile than vegetable food ; but as 
 the results on this point are contradictory, no great weight 
 can be attached to this influence. 
 
 The addition of fat to the ordinary flesh-diet of a dog 
 causes a considerable augmentation of the biliary secretion 
 (Nasse), but on an exclusive fat-diet animals secrete no more 
 bile than if they were actually starving. 
 
 Copious water-drinking increases the quantity of bile, and 
 not merely of its water but of its solid constituents. 
 
 Carbonate of soda in large doses occasions a considerable 
 diminution in the amount of bile, while calomel increases 
 the watery portion but not the solid constituents of the bile. 
 
 Both Nasse and Bidder and Schmidt found that the quan- 
 
THE BILE. 173 
 
 tity of bile was considerably diminished when the animals on 
 which they experimented presented any febrile symptoms. 
 
 (165.) Numerous and often opposite views have at different Functions 
 times been advanced regarding the functions of the bile. 
 
 The view that the secretion of the bile is mainly for the 
 purpose of purifying the blood of removing from it the 
 carbonaceous matters not separated by the lungs is opposed 
 by the following considerations : first, there is no evidence 
 that the quantity of bile is increased when the process of 
 oxidation in the lungs happens to be impeded; secondly, 
 pathological anatomy yields us no facts in favour of the view 
 that the liver can act vicariously for the lungs ; and, thirdly, 
 the separation of carbon by the liver is so inconsiderable as 
 compared with that by the lungs (being at most one-tenth, 
 and sometimes only one-fortieth according to Bidder and 
 Schmidt), that the liver can hardly be regarded as a purifier 
 of the blood in so far as the carbon is concerned. 
 
 The bile probably co-operates in more ways than one in the 
 general process of digestion. 
 
 One use that has been ascribed to it is to neutralise in the 
 small intestine the acid chyme which emerges from the 
 stomach. But the bile can contribute little or nothing to 
 the neutralisation of the free acid, because in the first place 
 the bile is very slightly alkaline and often perfectly neutral, 
 and, secondly, because the chyme in the intestine is still acid 
 after the admixture of the bile. The following reaction pro- 
 bably takes place : the alkali of the bile leaves the resinous 
 and fatty acids, with which it was combined in the bile, and 
 unites with the stronger acids of the chyme, namely, hydro- 
 chloric and lactic acids ; the biliary acids thus liberated give 
 an acid reaction to the chyme until they become decomposed. 
 
 The bile has also been asserted to possess a special solvent 
 action on the chyme, but none of its ordinary constituents 
 seem to be essentially changed, even when digested for a long 
 time with fresh bile ; and the only effect of this nature that is 
 
174 PHYSIOLOGICAL CHEMISTRY. 
 
 actually produced is probably due to the large quantity of 
 water in the biliary secretion. 
 
 It is doubtful how much importance should be attached to 
 the antiseptic action of the bile on the contents of the intes- 
 tinal canal. In favour of such a view it is alleged that when 
 no bile is poured into the intestine its contents very soon 
 undergo putrefactive decomposition a circumstance that is 
 sometimes observed in patients with jaundice, and which was 
 noticed by Frerichs in animals after tying the ductus chole- 
 dochus. On the other hand, other experimentalists have 
 found that animals, thus operated on, lived and discharged 
 normal excrements for many months. 
 
 Another use that has been assigned to the bile is that it 
 exerts a stimulating action on the intestinal walls, and thus 
 acts as a normal purgative. 
 
 But the main use of the bile seems to be to promote the 
 digestion of fatty matters. The bile possesses so small a 
 solvent action on the fats that the whole quantity which is 
 secreted would be quite insufficient to dissolve the amount of 
 fatty matter which is known to be absorbed by the intestines ; 
 but this secretion seems to exert a peculiar physical action on 
 the fat and on the intestinal walls, disintegrating the former 
 and impressing on the latter (by moistening the villi) a 
 peculiar condition which singularly facilitates the absorption 
 of fatty matters. This view is confirmed both by direct ex- 
 periments out of the body, and by observing the phenomena 
 that occur when the flow of bile into the intestine is pre- 
 vented. (1.) Wistinghausen* has shown by a series of accu- 
 
 * A tolerably full report of his inaugural dissertation, entitled "Endosmotic 
 Experiments on the Action of Bile on the Absorption of the Neutral Fats," is 
 given in Schmidt's " Jahrbiicher," 1852, vol. 75. p. 148. Instead of actual bile 
 he employed a solution of mixed glycocholate and taurocholate of soda (5g). 
 In a tube moistened with this fluid, oil rose 6*3 times higher than in a cor- 
 responding tube moistened with water; and when a mixture of 5 parts of this 
 solution, 1 of albumen and 1 of a solution of potash (1) was used, the oil rose 
 eight times higher. Bidder and Schmidt seem to have used actual bile in their 
 own experiments. Op. cit. p. 231. 
 
THE BILE. 175 
 
 rate observations (conducted under Schmidt's superintendence) 
 that oil will rise many times higher in a capillary tube 
 moistened with bile than in a similar tube when dry or when 
 moistened either with pure water or with a saline solution, 
 and similarly that it passes through membranes saturated 
 with bile far more readily than through similar membranes 
 moistened with water. (2.) It is found that those animals in 
 which the ductus choledochus has been tied, and whose bile 
 escapes externally through a fistulous opening, digest the 
 same quantities of albuminous and amylaceous food as 
 similar animals in a normal state ; but the case is very 
 different when the quantities of fat are compared with one 
 another which are retained in the body and applied to the 
 purposes of life by the animals that had been operated on and 
 by healthy animals. It has been clearly shown by Bidder 
 and Schmidt's experiments on dogs and cats, in which the 
 fatty matter in the food and in the excrements was compared, 
 that, although a certain quantity of fat is absorbed inde- 
 pendently of the action of bile, at least 2*5 times more is 
 absorbed in conjunction with the biliary secretion.* 
 
 In order to determine in another manner the influence of 
 the bile on the absorption of fat, the amount of fat in the 
 chyle obtained from the thoracic duct of healthy dogs, fed on 
 fat, was contrasted with that obtained from the corresponding 
 fluid obtained from dogs in which the bile did not flow into 
 the intestine. In two dogs with biliary fistulse the chyle 
 yielded 0'834-g- of fatty acids mixed with other organic 
 matters, and 0'113-g- of fatty acids with 0-190 of free fat 
 respectively, while the chyle of a healthy dog that eight 
 hours before its death had been fed upon raw beef, contained 
 3-244 of free fat with 0-058$ of fatty acids, f 
 
 * In other experiments they found that five and even seven times more fat 
 was absorbed when the bile flowed freely into the intestine than when it was 
 excluded. Op. cit. p. 224. 
 
 f If instead of taking the percentage in relation to the whole chyle we take 
 the percentage of the fat (including under this term both the free fat and the 
 
176 PHYSIOLOGICAL CHEMISTRY. 
 
 These experiments afford a complete demonstration of the 
 importance of the bile in relation to the absorption of fat, 
 and explain the mode in which it acts. 
 
 Schlossberger has lately suggested the probability that cer- 
 tain fatty matters occurring in the brain and nerves (cerebric 
 acid, oleophosphoric acid, &c.) take their origin from some of 
 the biliary constituents. We shall return to this subject in 
 Chapter XVI. in the Section on the " Composition of the Brain 
 and Nerves." 
 
 Formation (166.) It may now be regarded as an established fact that 
 the bile is actually formed in the liver, and that it is not 
 merely separated from the blood by that gland. This view 
 is established beyond all question by the following observa- 
 tions : 
 
 1. Several physiologists (amongst whom Moleschott should 
 be especially mentioned) have extirpated the livers of frogs, 
 and succeeded in keeping the mutilated animals alive for 
 some days. Neither the blood, lymph, flesh, nor urine of these 
 frogs yielded the slightest traces either of the resinous acids 
 or of the pigment of the bile. 
 
 2. Jaundice very seldom occurs in diseases of the paren- 
 chyma of the liver (almost never in fatty degeneration and in 
 tuberculosis of that organ, and very rarely in simple atrophy, 
 in granular liver, and in hepatitis), while it is almost con- 
 stantly present in diseases of the biliary ducts : if an accumu- 
 lation of biliary matters were induced in the blood by the 
 suppression of the hepatic secretion, jaundice would occur 
 just as frequently in the first class of diseases as in those 
 which present a mechanical impediment to the excretion of 
 the bile. 
 
 3. None of the essential constituents of the bile can be 
 detected in the portal blood. 
 
 fatty acids) in the solid residue, the numbers are 14'3g, 5'4g, and 39 -5g. The 
 analyses of the chyle are given in pp. 226-227. of Schmidt's book : they do not 
 differ from one another materially except in reference to the fats. 
 
THE BILE. 177 
 
 We have already shown in 28. that there are strong reasons 
 for believing that the non-nitrogenous resinous acid of the bile 
 (cholic acid) is formed from the oleic acid (or olein) of the 
 portal blood ; and this view is supported by the fact that the 
 amount of fat which is conveyed to the liver by the portal 
 vein is far greater than that which leaves it by the hepatic 
 veins, as well as by various arguments already given in p. 80. 
 
 How and where its adjuncts, taurine and glycine, are 
 formed is a more doubtful point. Taking into consideration 
 the facts mentioned in p. 31. regarding the modes in which gly- 
 cine is artificially obtained, and the evidence afforded by recent 
 researches (see p. 53.) regarding the occurrence of taurine in 
 the muscles of certain of the lower animals and in the lungs 
 and kidneys of mammals, little doubt can remain that these 
 substances are products of the regressive metamorphosis of 
 the nitrogenous tissues. Our tests for the detection of minute 
 traces of these substances are not sufficiently delicate to enable 
 us to state authoritatively that they must be formed in the 
 liver because we cannot discover their presence in the portal 
 blood. But there are other grounds which render it most 
 probable that their formation takes place in the liver. These 
 are (in the case of taurine): (1.) That there is considerably 
 more sulphur in the solid residue of portal blood than in that 
 of the blood of the hepatic veins (the ratio being, in Lehmann's 
 analyses, as O393 to 0-33 1-g-), and it is very probable that 
 this excess of sulphur (whether derived from the disintegra- 
 tion of the fibrin which takes place in the conversion of portal 
 into hepatic venous blood, as shown in 216, or from an 
 unknown sulphur-compound which Lehmann detected in the 
 spirit-extract of portal blood) is applied to the formation of 
 taurine ; and (in the case both of taurine and glycine) (2.) that 
 it is the ordinary chemical rule (and only few exceptions are 
 known) that conjugated compounds, such as taurocholic and 
 glycocholic acids, are not directly formed from the two bodies 
 into which they become separated on decomposition : chemical 
 
 N 
 
178 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 experience, therefore, renders it improbable that these con- 
 jugated acids should be formed from pre-existing taurine or 
 glycine and cholic acid ; and to this argument we may add 
 that there is an additional improbability in supposing that in 
 the regressive metamorphosis of tissues two comparatively 
 simple substances should combine to form much more com- 
 plicated ones. 
 
 We have already noticed the different views that have 
 been advocated regarding the formation of the bile-pigment 
 in p. 97. 
 
 SECTION IT. THE PANCREATIC FLUID. 
 
 Pancreatic (1^0 The pancreatic fluid, as obtained from a well-healed 
 fluid ; its permanent fistula, is a colourless, clear, somewhat viscid and 
 properties, ropy fluid, of a mawkish alkaline taste, devoid of any special 
 odour, and exhibiting a strong alkaline reaction. 
 
 Schmidt *, who has reinvestigated the chemical characters 
 of this fluid since the publication in 1852 of his great work 
 on " The Digestive Fluids," ascribes to it the following pro- 
 perties : Its specific gravity is I'OIO or 1-011, it froths 
 extremely on being shaken, instantaneously converts boiled 
 starch into dextrine and sugar at about 100 F., becomes 
 turbid at 158, and coagulates in white flakes at 162. It is 
 also coagulated by alcohol, the coagulum (pancreatic diastase) 
 redissolving in pure water and retaining its power of meta- 
 morphosing starch. By raising the pancreatic juice to the 
 boiling point this power is, however, destroyed, as also by the 
 addition of sulphuric, hydrochloric, nitric, and metaphosphoric 
 acids, and by corrosive sublimate, which form abundant 
 white precipitates; while acetic, sulphurous, and tribasic 
 phosphoric acids, potash, and ammonia, if added to the ex- 
 tent merely of a few drops, suspend the metamorphic action 
 without inducing even any turbidity. The two last-named 
 
 * Ann. d. Ch. u. Pharm. 1854, vol. xcii. p. 33. 
 
THE PANCKEATIC FLUID. 179 
 
 alkalies, as well as carbonate of ammonia, prevent the coagu- 
 lation by heat. Neutral acetate of lead produces a thick 
 white flocculent precipitate which partially redissolves in an 
 excess of the test ; both the precipitate and the solution act on 
 starch. This property of the pancreatic juice is, moreover, in 
 no way affected by the addition of bile or of gastric juice. It 
 has no power of establishing fermentation in saccharine fluids 
 or of converting urea into carbonate of ammonia. 
 
 This secretion is so prone to decomposition that after 
 exposure to the air for a few hours it developes a distinct 
 odour of putrefaction. 
 
 (168.) The principal constituent of the pancreatic juice is a Its chemi 
 substance closely resembling but not perfectly identical with 
 albuminate of soda ; it is the pancreatic diastase or ferment 
 to which allusion has already been made. It is to this sub- 
 stance that the pancreatic juice mainly owes its principal 
 chemical and physiological properties. The quantity in 
 which it occurs may be seen by a glance at the analyses 
 given below. 
 
 Amongst the other organic constituents we may mention a 
 butter-like fat which was found in small quantity (0-02 6 -) by 
 Frerichs in the pancreatic juice of the ass, and leucine and 
 tyrosine, which were detected in minute proportions by 
 Kolliker and Muller.* No trace of sulphocyanides has ever 
 been found in this secretion. 
 
 The mineral constituents consist chiefly of the chlorides of 
 sodium and potassium, and of the phosphates of the alkalies 
 and earths. 
 
 In the following table A. represents the mean of three 
 analyses (made by Schmidt) of the pancreatic juice of dogs in 
 which permanent fistulous openings had been established, 
 while B. represents the composition of the same secretion 
 immediately after the operation. The second analysis is 
 
 * Verhandl. d. phys.-med. Gessellsch. in Wurzburg, 1856, vol. vi. p. 506. 
 
 N 2 
 
180 PHYSIOLOGICAL CHEMISTRY. 
 
 given with the view of showing how much severe operations 
 may modify the animal fluids. 
 
 A. B. 
 
 Water , . . . ..*J *!>... 980-45 900-76 
 Solid constituents , 19-55 99-24 
 
 Pancreatic diastase or ferment . 12*71 90-44 
 
 Inorganic bases and salts , . . 6-84 8 '80 
 
 Soda combined with the ferment 3-31 0-58 
 
 Chloride of sodium . '.',*' 2-50 7'35 
 
 Chloride of potassium . . . 0-93 0-02 
 
 Phosphate of lime .... 0-07 0-41 
 Phosphate of magnesia' with 
 
 traces of oxide of iron . . 0-01 0-12 
 
 Tribasic phosphate of soda . . 0*01 
 Lime and magnesia combined 
 
 with the ferment . . . 0-01 0-32 
 
 The , pancreatic juice yielded by dogs with permanent 
 fistulous openings varied considerably in its composition ; the 
 collective solid constituents ranged from 1-5 to 2'3; the 
 organic matters from 0*9 to 1 -6-g-, and the inorganic bases and 
 salts from 0-62 to 0'75. 
 
 Its daily (169.) Calculating from the quantity of pancreatic juice 
 
 secreted by dogs of known weight in a given time, Schmidt 
 infers that a man weighing ten stones secretes daily 4-6 kilo- 
 grammes, or about 10 Ibs. of this fluid. 
 
 Various circumstances modify the amount of the secretion : 
 thus Ludwig and Weinmann found that prolonged hunger, 
 vomiting, and severe operations (such as establishing fistulous 
 openings) diminished the quantity, while it was increased by 
 the ingestion of solid food or of fluids. The flow seemed to 
 attain its maximum in twelve or thirteen minutes after water 
 had been taken. 
 
THE PANCKEATIC FLUID. 181 
 
 The following inferences are drawn by Kroeger from 
 numerous observations : 
 
 1. The ingestion of food exercises great influence over this 
 secretion, the latter becoming much increased in quantity 
 almost immediately after meals, and reaching its maximum 
 in half an hour or three quarters after the meal, when it is 
 six or ten times larger than it had been just before the 
 ingestion of food. 
 
 2. Water does not produce a similar effect ; on the con- 
 trary, when taken simultaneously with solid food, it prevents 
 the latter from causing so evident an increase. 
 
 3. The concentration of the pancreatic juice is commonly, 
 but not invariably, diminished in the same proportion as the 
 quantity is increased.* 
 
 (170.) One of the chief uses of the pancreatic juice in rela- Its func- 
 tion to digestion is doubtless to convert into sugar the 
 amylaceous matters which have escaped the action of the 
 saliva and have passed unchanged into the duodenum. The 
 pancreatic juice possesses this property in a far higher degree 
 than the saliva, and this power is not impeded by an ad- 
 mixture of bile, gastric juice, or free acids. Comparative 
 anatomy supports this view, which was established on purely 
 chemical data, for the pancreas is found to be much more deve- 
 loped in herbivorous than in carnivorous animals. 
 
 Bernard claims for the pancreatic fluid another and 
 apparently a more important function ; he believes that he 
 has proved that it is solely by the action of this fluid that 
 the fat is reduced to a condition in which it can be absorbed 
 and digested; that is to say, that it is decomposed into 
 glycerine and a fatty acid. It is unquestionable that if pan- 
 creatic juice and fat be shaken together in a test tube an 
 emulsion is immediately formed and the fat is in a short time 
 decomposed into acid and base. But the experiments of 
 Frerichs, Lenz, Bidder and Schmidt, and Lehmann seem to 
 
 * Diss. Inaug. de Succo Pancreatico, Dorpat, 1854, pp. 40, 41. 
 N 3 
 
182 PHYSIOLOGICAL CHEMISTRY. 
 
 afford conclusive evidence that a similar result does not take 
 place in the intestinal canal, and it is most probable that it 
 is in consequence of its admixture with the acid gastric juice 
 that the pancreatic fluid loses this property. In support 
 of the view held by Bernard's opponents it may be further 
 urged that the chyle always contains a far larger amount of the 
 neutral fats than of fatty acids, and that after the establish- 
 ment of a fistulous opening which allows of the external escape 
 of the pancreatic fluid, the fat taken with the food seems to be 
 absorbed as readily and completely as before the operation.* 
 
 Considering the large quantity of pancreatic juice yielded 
 in the twenty-four hours (about 10 Ibs.), Schmidt is of 
 opinion that the function of this fluid is not so much to 
 promote the conversion of starch into sugar as for the 
 purpose of diluting the chyme, and for reconverting the 
 soda (which in the pancreas has been separated from the 
 chlorine of the chloride of sodium and has combined with 
 organic matter) into chloride of sodium. According to this 
 view he shows from numerical calculations that more than 
 half of the chloride of sodium existing in the blood circu- 
 lating through the pancreas, is broken up into hydrochloric 
 acid and soda, of which the former is separated by the glands 
 which secrete the gastric juice, while the latter unites with 
 the pancreatic diastase or ferment. Meeting again in the 
 upper part of the intestinal canal the hydrochloric acid and 
 the soda re-unite and re-form chloride of sodium, which is 
 again absorbed and re-enters the circulation. 
 
 We have already referred to the occurrence of leucine in 
 the pancreatic fluid and in the saliva. It is possible that its 
 decomposition may give rise to the volatile fatty acids which 
 are occasionally found in the stomach and small intestine, f 
 
 * Bernard still maintains the accuracy of his views, and asserts that his 
 opponents failed in confirming them from an imperfect anatomical knowledge 
 of the parts on which they operated. See his "Le9ons de Physiologie Ex- 
 perimentale," 1856, voL ii. pp. 335 349. 
 
 f See note to page 32. 
 
THE INTESTINAL JUICE. 183 
 
 SECTION V. THE INTESTINAL JUICE. 
 
 (171.) The intestinal juice secreted by the glands of The intes- 
 Lieberkiihn and other glandular structures embedded in the its proper-' 
 mucous coat of the intestine is a colourless (or, according to ties * 
 Kolliker, yellowish), ropy, viscid fluid, which is invariably 
 alkaline ; the alkalinity, however, varies in different animals 
 and in different parts of the intestine. 
 
 The morphotic elements occurring in the intestinal juice 
 are a certain number of granular cells, nuclei, sometimes a 
 few fat globules, and not unfrequently cylinder epithelium. 
 
 After the removal (by filtration) of these elements, the Its chemi- 
 fluid (according to Schmidt) does not contain a trace of position, 
 albumen, and, therefore, does not coagulate either on boiling 
 or the addition of acetic acid ; according to Kolliker, how- 
 ever, a couple of drops of acetic acid produce a turbidity in 
 the heated (but not the cold) fluid, which disappears on the 
 addition of an excess of the reagent. Acetate of lead, nitric 
 acid, and alcohol throw down tolerably abundant precipitates. 
 
 In the following table A represents the composition of a 
 filtered and B of an unfiltered specimen of the intestinal 
 juice of the dog. The analyses were made by Schmidt. 
 
 Water s , , > 965-33 
 
 Solid matters not volatile at 248 . ? ,, * "> 34-67 
 
 Substances soluble in alcohol of 85% (bile and 
 
 soluble salts) '^ :..--*: :r - ^l -^ . 25-12 
 
 Substances insoluble in alcohol of 85% (pan- 
 creatic and intestinal ferments and insoluble 
 salts) 9-55 
 
 In 100 parts of the substances soluble in alcohol there were 
 contained : 
 
 N 4 
 
184 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Its quan- 
 tity. 
 
 Its func- 
 tions. 
 
 Fat . . . . 2-80 
 
 Biliary acids in combination with soda . . . 65 -96 
 
 Taurine . . . .V 5 "i r "v" ". . . 1'03 
 
 Other organic matters ^. * ., .... - . 14-80 
 
 Inorganic constituents (chiefly chloride of sodium) 1 5 '4 1 
 
 B. 
 
 Water ' . 
 
 Soluble matters not volatile at 248 
 
 . 969-58 
 30-42 
 
 Insoluble epithelial structures with earthy 
 
 phosphates . . . . < v . 8-65 
 
 Pancreatic and intestinal ferments soluble in 
 
 water . -,."., . r -,^ - 5*84 
 
 Biliary constituents and salts soluble in alcohol 15-93 
 
 It is obvious that in both these cases the intestinal juice 
 was far from pure. 
 
 (172.) The quantity of intestinal juice secreted in a given 
 time, cannot be accurately determined ; it seems, however; to 
 reach its maximum in the small intestine five or six hours 
 after a meal, and to be much and rapidly increased by the in- 
 gestion of fluids.* Schmidt estimates from a rough calcula- 
 tion, that an adult man weighing ten stones secretes in 
 twenty-four hours about 300 grammes of intestinal juice. 
 
 (173.) The intestinal juice seems to unite in itself the 
 leading powers of the pancreatic fluid and the gastric juice ; 
 that is to say, it resembles the former in converting starch 
 into sugar, and the latter in dissolving flesh and the other 
 protein-bodies. 
 
 Starch, in the form of paste, when introduced into loops of 
 
 * It is worthy of remark that the intestinal juice which flows abundantly 
 after drink has been taken, exhibits the same concentration as before the inges- 
 tion of the fluid ; hence it must be inferred that the drink is absorbed in the 
 stomach, and perhaps in the upper part of the small intestine, and that the 
 water which thus finds its way into the blood, increases the intestinal juice in 
 common with the other secretions. 
 
THE INTESTINAL JUICE. 185 
 
 gut tied at both ends and re-introduced into the abdominal 
 cavity, was usually found in Schmidt's experiments to be con- 
 verted in the course of three hours into a thin fluid mass, 
 which no longer yielded any reaction with iodine, but gave 
 undoubted evidence of the presence of sugar. On mixing 
 together starch-paste and intestinal juice out of the body at a 
 temperature of about 100, an abundance of sugar was found 
 in the mixture in a quarter of an hour. 
 
 In a similar way pieces of flesh or coagulated albumen were 
 introduced into tied loops, and in the course of from six to 
 fourteen hours they were found to be for the most part 
 or entirely dissolved. Schmidt also showed by experiments 
 made externally to the organism, that the intestinal juice 
 both when mixed with bile and pancreatic juice, as well as in 
 its pure state, possesses the power of dissolving the protein- 
 bodies. Kolliker and Miiller,* and likewise Funke,f failed 
 in observing any solvent action of the intestinal juice on the 
 protein-bodies in the case of the rabbit, but the former 
 observers afterwards fully confirmed Schmidt's results in ex- 
 perimenting on cats. 
 
 We have previously stated (see p. 165.) that a very large 
 amount of albuminates passes undigested from the stomach, 
 and that the quantity of gastric juice which is secreted is not 
 sufficient to dissolve the protein-matters necessary for nutri- 
 tion ; and hence we should have concluded, a priori, that 
 nature had provided some additional solvent for flesh, albu- 
 men, &c., and the same remark applies to the fluids which 
 effect the metamorphosis of starch, for Schmidt has shown 
 that the pancreatic juice is absorbed and disappears before it 
 reaches the middle of the small intestine J, and yet we find 
 that starch is readily converted into sugar below that point. 
 
 * Verhandl. d. phys.-med. Gesellsch. in Wurzburg. 1856, vol. vii. p. 509. 
 f See his edition of Wagner's " Lehrbuch d. Speciellen Physiologic," 1855, 
 pp. 220 222. 
 
 J Schmidt found that the contents of the intestine are unable, beyond that 
 
186 
 
 PHYSIOLOGICAL CHEMISTKY. 
 
 Composi- 
 tion of in- 
 testinal 
 contents. 
 
 SECTION VI. THE CONTENTS OF THE INTESTINAL CANAL. 
 
 (174.) This section, which must be regarded as supplemen- 
 tary to the previous ones, includes the consideration of various 
 substances for which it is not easy to find a better position, 
 namely: (l.)the semi-solid contents of the small intestine; 
 (2.) the gases contained in the intestinal canal; (3.) vomited 
 matters ; (4.) the contents of the foetal intestine and the meco- 
 nium ; and (5.) the excrements in health and disease. 
 
 1. The semi-solid Contents of the Small Intestine. 
 
 (175.) On laying open the small intestine, we usually find 
 an admixture of imperfectly digested and indigestible sub- 
 stances, associated with food which has already undergone 
 change, and 'with the constituents of the digestive fluids in 
 every stage of metamorphosis. 
 
 The reaction of the intestinal contents varies in different 
 parts of the intestinal canal, and is to a certain degree depen- 
 dent on the nature of the food. The contents of the stomach 
 always redden litmus paper, whatever kind of food has been 
 taken. The duodenal contents, notwithstanding the admix- 
 ture of the bile and pancreatic juice, are likewise always acid, 
 although in a far less intense degree than those of the sto- 
 mach. In the. jejunum, we usually meet with only a faint 
 acid reaction, which altogether disappears in the ileum, while 
 in the caecum (and sometimes in the lower part of the ileum) 
 an alkaline reaction is manifested. After a purely flesh-diet, 
 the acid reaction disappears shortly below the duodenum, 
 while after the ingestion of vegetable food it often extends 
 through more than half the small intestine, and sometimes 
 (especially after the use of sugar) to the caecum. As a 
 
 point, to separate butyric acid from butter, which is a property of the pan- 
 creatic juice. 
 
THE CONTENTS OF THE SMALL INTESTINE. 187 
 
 general rule, the contents of the large intestine are alkaline ; 
 it very often, however, happens that the interior of the mass 
 is strongly acid, while the outer parts which are moistened 
 with the intestinal juice are neutral or alkaline. 
 
 The acid reaction presented by the contents of the stomach 
 is mainly due to the free acid of the gastric juice, and in the 
 duodenum the free acid is chiefly dependent on the same 
 sources, although the liberated and as yet undecomposed 
 biliary acids may co-operate in producing this acid reaction. 
 The lactic acid which is found in the lower part of the small 
 intestine, and in the large intestine after the free use of 
 starch or sugar, is unquestionably mainly due to the decom- 
 position and fermentation of the food, and must not be 
 regarded as a secretion from the intestinal walls; and the 
 butyric acid that is occasionally found in these parts must be 
 referred to a similar source. We have already (see pp. 32-33.) 
 noticed the possibility of leucine slightly contributing to the 
 development of volatile fatty acids in the intestine. The 
 alkaline reaction of the contents of the large intestine is 
 chiefly due to the preponderance of the alkaline intestinal 
 juice ; Lehmann believes, however, that it may be sometimes 
 increased by a development of ammonia. 
 
 In consequence of the rapid absorption that goes on along Soluble 
 the intestinal surface, we meet with a comparatively small tuents. 
 proportion of soluble matters in these contents. Amongst 
 these soluble matters we often find glycose, which seems to Glycose- 
 owe its origin to the action of the pancreatic fluid and 
 intestinal juice upon starch, and not to sugar having been 
 present in the food ; for after saccharine food has been taken 
 we very rarely meet with this substance in the small intestine, 
 and then only in its upper part, its absorption taking place 
 with great rapidity. 
 
 In the aqueous extract of the contents of the small intestine A coagul 
 we always find small quantities of a protein-body coagulable ^7!' 
 by heat and usually precipitable by acetic acid. Since the 
 
188 PHYSIOLOGICAL CHEMISTRY. 
 
 protein-bodies are converted during digestion (see p. 163) into 
 soluble but non-coagulable substances (the peptones) ; since 
 the coagulable matter of the pancreatic juice (the pancreatic 
 diastase or ferment) is soon absorbed by the intestine (see 
 the note to p. 185.); and since, further, this coagulable protein- 
 body is equally found in the intestine after the use of 
 vegetable food poor in protein-bodies, and even of non- 
 nitrogenous food, it seems almost certain that the origin of 
 this substance must be referred to an exudation of albuminous 
 matter from the intestinal capillaries in accordance with the 
 laws of endosmosis. 
 
 Dextrine J n the filtered contents of the small intestine we only 
 and pep- 
 tones, rarely find dextrine (Lehmann never succeeded in detecting 
 
 it), and never more than small quantites of peptones. 
 
 Biliary con- In the alcoholic extract of the intestinal contents we can 
 almost always obtain evidence of the presence of biliary con- 
 stituents. In the duodenum and for a little way beyond it 
 we find the unchanged conjugated biliary acids ; as we 
 descend further we find less of these acids, but a compara- 
 tively larger amount of the products of their disintegration, 
 namely, choloidic acid, taurine, and dyslysin ; while in the 
 large intestine we have usually little more than a trace of 
 choloidic acid and taurine. These chemical observations are 
 confirmatory of experiments instituted by Schmidt, which 
 show that nearly half the bile which is poured into the 
 duodenum is decomposed before it reaches the middle of the 
 small intestine. 
 
 Bile-pig- The bile-pigment undergoes the same changes in the intes- 
 
 tinal canal as are observed to occur in the decomposition of 
 the bile. In the alcoholic extract of the contents of the small 
 intestine we usually obtain the well-known changes of colour 
 on the addition of nitric acid (seep. 96). The yellowish- 
 brown colour of the excrements is apparently due to highly 
 oxidised bile-pigment. 
 
INTESTINAL GASES. 
 
 189 
 
 Cholesterin is always to be detected in the intestinal con- Choles- 
 tents, and is doubtless derived from the bile. 
 
 A little fat is usually found along the whole course of the Fat. 
 intestinal canal, especially after an animal diet. 
 
 Amongst the insoluble constituents of the intestinal contents Insoluble 
 may be mentioned almost all remains of undigested or 
 indigestible food, such as starch-granules, partially dissolved 
 muscular fibre, fragments of bone, various constituents of the 
 vegetable tissues, yeast-cells *, &c. 
 
 2. The Gases contained in the Intestinal CanaL 
 
 (176.) The gases which are found in the intestinal canal owe Intestinal 
 their origin partly to air conveyed into the stomach from 
 without, partly to the decomposition of the intestinal contents, 
 and partly to an interchange of the preceding gases with those 
 contained in the blood of the intestinal capillaries. The 
 most trustworthy observations on the nature of these gases 
 are those instituted by Magendie and Chevreul, who examined 
 the gaseous contents of the stomach and small and large 
 intestines of three criminals immediately after their execu- 
 tion, and those of Valentin on two horses which he killed by 
 bleeding. 
 
 The following are the results obtained by Magendie and 
 Chevreul : 
 
 
 Stomach. 
 
 Small Intestine. 
 
 Large Intestine. 
 
 Carbonic acid 
 
 14-00 
 
 1. 2. 3. 
 24-39 40-00 25-00 
 
 1. 2. 3. 
 43-50 70-0 22-50 
 
 Oxygen .... 
 Nitrogen 
 Hydrogen . 
 Carburetted hydrogen 
 
 11-00 
 71-45 
 3-55 
 
 20-08 8-85 66-60 
 55-53 51-15 8-40 
 
 5103 18-4 67-50 
 ) n . fi 7-50 
 5-47 1 1] 12-50 
 
 * These are stated to be of common occurrence after the use of pastry. 
 
190 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 The hydrogen and that part of the carbonic acid which is 
 not derived from the blood are products of fermentation ; and 
 we may suppose them produced in the following manner : 
 
 2 at. lactic acid (C J2 H 10 10 ) + 2 at. water (H 2 2 ) = 1 at. 
 hydrated butyric acid (C 8 H 8 4 ) + 4 at. carbonic acid (C 4 8 ) 
 -f 4 at. hydrogen (H 4 ). 
 
 Flatus passed from the anus presents much the same com- 
 position as the gas found in the large intestine, but it usually 
 has a more marked faecal odour. In two analyses of such 
 flatus Marchand found : 
 
 Carbonic acid . ^ v , . 44-5 36-5 
 
 Nitrogen . . , . 14-0 29-0 
 
 Hydrogen . V , . 25-8 13 '5 
 
 Carburetted hydrogen . 15*5 22*0 
 Sulphuretted hydrogen . 1-0 
 
 Valentin's analyses are probably the most accurate, but in 
 consequence of the different nature of the food it is uncertain 
 how far the gases found in the intestinal canal of the horse 
 correspond with those occurring in the human subject. The 
 two horses are indicated by A and B. 
 
 
 
 Upper 
 
 Middle 
 
 Lower 
 
 
 Middle 
 
 
 Stomach. 
 
 part of 
 small 
 
 part of 
 small 
 
 part of 
 small 
 
 Caecum. 
 
 portion 
 of 
 
 
 
 Intestine. 
 
 Intestine. 
 
 Intestine. 
 
 
 Rectum. 
 
 
 A. B. 
 
 A. 
 
 B. 
 
 B. 
 
 A. B. 
 
 A. 
 
 Carbonic acid 
 
 44-35 55-64 
 
 18-83 
 
 41-78 
 
 19-41 
 
 7770 71-59 
 
 47-94 
 
 Oxygen . 
 
 7'16 077 
 
 5-76 
 
 
 
 4-97 
 
 
 
 
 
 Nitrogen 
 
 44-23 25-38 
 
 73-35 
 
 48-70 
 
 73-31 
 
 10-23 16-32 
 
 24-39 
 
 Hydrogen . 
 
 0-66 13-29 
 
 
 
 0-02 
 
 0-08 
 
 4-67 0-2C 
 
 13-82 
 
 Carburetted 1 
 hydrogen J 
 
 0-90 
 
 0-45 
 
 4-98 
 
 0-77 
 
 4-09 6-96 
 
 11-82 
 
 Sulphuretted 1 
 hydrogen J 
 
 2-70 4-92 
 
 1-61 
 
 452 
 
 1-46 
 
 2-02 3-71 
 
 0-54 
 
 Ammonia 
 
 _ . 
 
 ~~~ 
 
 ~~ 
 
 
 
 1-29 1-22 
 
 1-49 
 
 The coincidence of an excess of carbonic acid in the 
 stomach and the caecum seems to be in connection with the 
 digestive function which the latter organ discharges in the 
 
VOMITED MATTERS. 191 
 
 herbivora. Valentin agrees with previous observers regarding 
 the total absence of oxygen in the gases of the large intes- 
 tines. The relatively large quantities of carburetted hydrogen 
 and hydrogen in the rectum show, he thinks, that changes 
 in the remains of the food continue to take place up to the 
 last portions of the digestive canal. 
 
 In cases of morbid digestion, I have occasionally met with 
 such an abundance of sulphuretted hydrogen in the eructations 
 as to be very unpleasant to the patient. These cases are, I 
 believe, generally associated with the presence of oxalate of 
 lime in the urine, and both symptoms usually disappear 
 under the use of the mineral acids. 
 
 3. Vomited Matters. 
 
 (177.) It is unnecessary to notice that kind of vomit which Vomited 
 consists of partly digested food mixed with the digestive fluid. 
 The matters which in certain diseases are vomited in the 
 fasting state, and which are actually secreted fluids, are, how- 
 ever, of sufficient pathological importance to merit a notice 
 in this section. 
 
 In many forms of gastric disease, as for instance in the In gastric 
 chronic gastric catarrh of drunkards, and sometimes in cancer 
 and perforating ulcer of the stomach, there is an abundance 
 of saliva secreted which accumulates in the stomach, and 
 finally induces vomiting. In such cases the vomited matters 
 present all the characters of saliva ; they are usually alkaline, 
 but sometimes neutral or even acid, contain sulphocyanides, 
 and have the power of converting starch into sugar. 
 
 The rice-water matters vomited in cholera have been fre- in cholera, 
 quently analysed. They usually present a faint mawkish 
 odour, and their reaction may be acid, neutral, or alkaline. 
 On standing they deposit epithelial structures (usually cylin- 
 drical epithelium) and mucus, the supernatant fluid being 
 clear and yellowish The fluid contains little organic matter, 
 
192 PHYSIOLOGICAL CHEMISTRY. 
 
 but a relatively large amount of inorganic salts, chiefly chlo- 
 ride of sodium. In the early stage, the vomited matter is 
 acid, and butyric and acetic acids have been detected in it. 
 When the fluid is acid or neutral, and contains no remains of 
 food, urea is constantly present. If, on the other hand, the 
 disease is further advanced, and symptoms of uraemia are 
 established, the vomited matter contains carbonate of ammonia, 
 and consequently has an alkaline reaction. Albumen occurs 
 only very sparingly when the fluid is acid, but more abun- 
 dantly when there is an alkaline reaction. 
 
 In searching for biliary constituents or blood in vomited 
 matters, it must not be forgotten that the free acid of the gastric 
 juice may very much modify them. For instance, in certain 
 forms of peritonitis and cerebral inflammation, we may have 
 a grass-green colour developed from the action of the acid on 
 the brown bile-pigment ; and similarly the action of the acid 
 on the blood-corpuscles may give rise to those varieties of 
 brown or black vomit with which most physicians are 
 familiar. 
 
 4. The Contents of the Foetal Intestine and the Meconium. 
 
 (178.) According to Lehmann, the small intestine of the 
 human foetus, between the fifth and sixth month, always con- 
 tains a bright yellow mass, which is either neutral or faintly 
 acid. From 89 to 96-g- of the solid residue of this mass is 
 composed of epithelial structures and mucus, while the re- 
 mainder consists of oleic and margaric acids, a little fat, 
 taurocholate and glycocholate of soda, a casein-like substance 
 (probably albuminate of soda), and the chlorides of sodium 
 and potassium. The presence of bile in the foetal intestine 
 is confirmed by an examination, made by Schlossberger, of the 
 yellow mucus contained in the small intestine of a foetal calf 
 at the fortieth week, which yielded indications both of the 
 biliary acids and of bile-pigment. 
 
THE F^CES. 193 
 
 The contents of the large intestine of the foetus in and after 
 the seventh month are almost perfectly identical with the 
 meconium discharged after birth; occurring in tolerably 
 compact masses of a brownish green or almost black colour, 
 without odour, and rapidly putrefying on exposure to the air. 
 As a general rule, Lehmann has found the contents of the 
 large intestine, as well as the meconium, acid ; occasionally, 
 however, they are neutral. The microscope reveals the pre- 
 sence of an abundance of cylinder epithelium of a beautiful 
 green tint, of mucus-corpuscles, and of fat (with which there 
 is a good deal of cholesterin). Neither the biliary acids nor 
 bile-pigment can be detected in it, nor does it contain any 
 substance precipitable by heat or acetic acid.* 
 
 5. The Excrements in Health and Disease. 
 
 (179.) The solid excrements, or the fseces, consist of a mix- TheFseces. 
 ture composed of undigested particles of food (such as vege- 
 table cellular tissue, fragments of tendon, skin, half-digested 
 muscular fibre), of epithelium and mucus (derived from the 
 intestinal walls), and of traces of the decomposed biliary 
 constituents. 
 
 After the use of fatty food, a considerable quantity of fat 
 may be found in the excrements, in consequence of the com- 
 paratively small power which the intestine possesses of 
 absorbing that substance, as has been shown by the expe- 
 riments of Boussingault and others; and when starch or 
 sugar has been taken freely, sugar (although only in small 
 quantity, in consequence of the readiness with which it is 
 absorbed) is often present. Moreover, the excrement always 
 
 * In an analysis of meconium made by Simon, both casein and albumen 
 were found in very considerable quantity. Dr. Davy, however, like Lehmann, 
 did not find any protein-body. The analyses of Simon and Davy may be seen 
 in my Translation of " Simon's Animal Chemistry," Lond. 1846, vol. ii. pp. 
 367-369. 
 
 O 
 
194 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Their 
 odour. 
 
 Their co- 
 lour. 
 
 Their daily 
 quantity. 
 
 contains a certain amount of salts, whose composition will 
 presently be noticed. 
 
 The peculiar odour of the faeces is chiefly dependent, 
 according to Valentin, on the decomposed bile ; while Liebig 
 refers it to a decomposition of albuminous matters, founding 
 his view on the fact that something like a faecal odour may be 
 produced by burning albumen with potash. In consequence 
 of the small quantity of albumen in the contents of the large 
 intestine, the former view is the more probable, and it is fur- 
 ther supported by the circumstance that the peculiar faecal 
 odour disappears, and is replaced by a strong putrid smell, 
 when, as in cases of jaundice, the bile does not flow into the 
 intestine. 
 
 The colour of the normal faeces varies with the food ; on a 
 mixed diet they are of a yellowish-brown tint, on a flesh diet 
 much darker, and on a milk-diet quite yellow. On exposure 
 to the air the colour becomes darker ; and, on the addition of 
 very dilute nitric acid a red tint is always developed. 
 
 The consistence seems chiefly to depend upon the constitu- 
 tional relations of the individual; but it is considerably 
 influenced by bodily exercise. As a general rule the longer 
 the excrements are retained in the intestine the greater is 
 their consistence. 
 
 The reaction is most commonly alkaline, but no very defi- 
 nite rule can be laid down on this point. According to 
 Marcet, the reaction is constantly alkaline; according to 
 Lehmann and Wehsarg, generally acid, but very often alka- 
 line or neutral. 
 
 The quantity of the daily faeces is very variable. The 
 mean of seventeen observations made by Wehsarg* was 131 
 grammes (or about 4*6 ounces), the largest and smallest 
 quantities being 306 and 67*2 grammes respectively. There 
 is no definite relation between the amount of faeces and the 
 
 Mikroskopische und chemische Untersuchungen der Fseces gesunder 
 erwachsener Menschen. Giessen. 1853. 
 
THE F.ECES. 195 
 
 bodily weight ; the quantity of faeces seems rather to be con- 
 nected with the digestive power of the individual. 
 
 The faeces, when in a formed or half-formed state, contain 
 on an average 73'3-g- of water and other matters volatile at 
 248, and 26-7-g- of solid constituents; in seventeen observa- 
 tions the latter varied from 17 '4 to 31'7-g-. 
 
 The absolute quantity of solid matter discharged in the 
 twenty-four hours averages thirty grammes (or rather less 
 than one ounce) ; the extremes being 57*2 and 163 grammes. 
 
 The amount of undigested matters varies very much in 
 different cases, the mean quantity in ten observations was 
 3 4 grammes (about fifty-two grains), or 8'3-g-; the extremes 
 being 8-2 grammes and 0-81 of a gramme. 
 
 The ether-extract of the faeces varies extremely, according 
 to Wehsarg, with the nature of the food. After a very fatty 
 diet it rose to 31 '2 grammes (about an ounce) or 58*2-- of the 
 dried residue; the mean was 11*5$, and the minimum 8'5-g-. 
 It consisted for the most part of a waxy fat. 
 
 The alcohol-extract was found to amount (as the mean of 
 three observations) to 15 '6%, and it may rise to double this 
 quantity in diarrhoea. Wehsarg could only once detect the 
 presence of bile in it with certainty, although he often got 
 doubtful indications ; and on the addition of nitric acid to 
 fresh faeces, he only twice obtained undoubted evidence of 
 bile-pigment. 
 
 The water-extract is a brownish-black mass which under- 
 goes decomposition on drying, and averages about 20$ of the 
 dry faeces. 
 
 Liebig, many years ago, made the observation that the Their mi- 
 solid excrements contain only a small amount of soluble 
 salts, these being mainly carried off by the urine. The 
 mineral constituents have been examined by Berzelius, Ender- 
 lin, Lehmann, Fleitmann, and Porter, and, as a general result, 
 it may be stated that the mineral constituents yielded by the 
 incineration of dried human faeces amount on an average to 
 
 02 
 
196 PHYSIOLOGICAL CHEMISTRY. 
 
 6-7-J, of which only 1-54 (or 23 of the ash) are soluble 
 salts. Berzelius first directed attention to the fact that 'more 
 lime than magnesia must be absorbed in the intestine, since 
 we find in the solid excrements less lime and relatively more 
 magnesia than in the food that has been taken ; the ratio of 
 the magnesia to the lime in the excrements being as 1 : 2 or 
 1 : 2-5. In 100 parts of ash, Fleitmann found 21-36 of lime 
 with 10-67 of magnesia, and Porter 26-46 of lime with 10-54 
 of magnesia. The principal acid which occurs in the faeces 
 in combination with the earths and alkalies, is tribasic phos- 
 phoric acid, which, according to Fleitmann, forms nearly 31, 
 and according to Porter, more than 36^- of the faecal ash. 
 Crystals of phosphate of ammonia and magnesia may often be 
 detected by the microscope in perfectly normal evacuations of 
 a neutral or alkaline reaction, although they are far more 
 abundant in those diseases in which the contents of the bowels 
 are especially prone to decomposition, as in typhus, cholera, 
 and certain forms of dysentery. 
 
 A certain amount of silica, taken either as sand with 
 various articles of food (as, for instance, brown sugar) or in 
 the siliceous structure of various plants, is always found in the 
 excrements. Berzelius found that the faecal ash contained 
 more than 12, and Enderlin nearly 10 of this constituent. 
 
 Undecomposed bile only occurs in the excrements when 
 the intestinal contents pass more rapidly than usual through 
 the bowels ; as, for instance, after the use of saline and acrid 
 purgatives and in certain forms of diarrhoea Pettenkofer's 
 test will then reveal its presence : taurine may, however, be re- 
 garded as a common if not a constant ingredient of the faeces.* 
 
 * In the preceding remarks I have refrained from noticing Dr. Marcet's 
 recent investigations in consequence of their comparative incompleteness. His 
 principal conclusions are that human evacuations in the healthy condition 
 contain: 1. A new organic immediate principle, which he terms excretine, 
 having a crystalline structure, an alkaline reaction, and represented by the 
 formula C 78 H 78 SO a . 2. A substance possessing the character of margaric 
 acid, which is chiefly found after the use of vegetable food, and occurs mostly 
 
THE FJSCES. 197 
 
 (180.) The bright yellow semifluid excrements of infants Yellow 
 at the breast contain, as was shown by Simon *, a large of infant"' 
 quantity of fat, a considerable amount of coagulated bile, 
 undigested casein, and a sufficient quantity both of the biliary 
 acids and bile-pigment to give certain evidence of the 
 presence of these bodies by Pettenkofer's test and by nitric 
 acid respectively. Epithelial structures are moreover present. 
 
 (181.) The excrements sometimes present a green colour, Green ex- 
 which, until comparatively recently, was regarded as a sign crements - 
 of the presence of an excess of bile. This is, however, seldom 
 the cause of a green colouration of the faeces, and only occurs 
 when there is at the same time an excess of bile and a pre- 
 ponderance of free acid in the intestine; as, for instance, in 
 icterus neonatorum. In these cases the ordinary brown bile- 
 pigment seems to be converted into the modification termed 
 bilifulvin. As we shall presently show, the presence of blood 
 may sometimes give rise to a green colour. 
 
 Lehmann has confirmed the observations of Hone and 
 others, regarding the occurrence of sulphide (sulphuret) of 
 mercury in the green or greenish-black stools that are voided 
 after the use of calomel. The colour in this case seems due 
 partly to the presence of almost unchanged bile, and partly to 
 that of the mercurial compound. 
 
 The excrements often assume a black or dark green colour 
 after the prolonged use of ferruginous preparations or chaly- 
 beate waters (especially such as contain sulphate of soda with 
 carbonate of protoxide of iron). Lehmann has definitely 
 shown, from analyses of the green and black excrements of 
 persons taking the Marienbad waters, that the colour is here 
 due to the presence of protosulphide of iron. 
 
 free, but partly in combination with lime and magnesia. 3. A colouring 
 matter analogous to that of the blood. *4. An olive-coloured fatty acid, for 
 which he proposes the term excretoleic acid. 5. Volatile fatty acids, free, how- 
 ever, from butyric acid. 
 
 * Animal Chemistry, vol. ii. p. 369. 
 
 o 3 
 
198 PHYSIOLOGICAL CHEMISTRY. 
 
 The excrements are usually green after the medicinal 
 use of indigo, and are often black after charcoal has been 
 taken. 
 
 As only a definite quantity of fat can be absorbed by the 
 intestines in a given time, food very rich in fat or the in- 
 gestion of cod-liver or other oils may give rise to the presence 
 of a large quantity of fat in the excrements. In some 
 diseases, especially such as specially interfere with the general 
 nutritive processes, such as pulmonary phthisis, Bright's 
 disease, diabetes mellitus *, and more particularly diseased 
 conditions of the pancreas, an augmentation of the fat in 
 the faeces is often observed. 
 
 Sugar has been occasionally found, but it is not always 
 present, in the excrements of diabetic patients. 
 
 The occurrence of blood in the faeces is by no means rare. 
 Omitting all notice of those cases in which its presence is too 
 obvious to be overlooked, we may remark that when the 
 haemorrhage is very slight, and proceeds from the stomach or 
 small intestine, it may impress upon the faeces a peculiar 
 colour and appearance, whose cause may easily escape 
 recognition. In such cases we often have black or choco- 
 late-coloured tar-like stools, in which imperfect blood-cor- 
 puscles can be discovered by the microscope, and in which 
 haematin can be chemically detected. In some of the 
 intestinal diseases of young children, and occasionally in 
 some forms of continued fever, semi-fluid green excrements 
 are discharged which owe their colour to a slight admixture 
 of blood which may be readily detected by the microscope. 
 
 Albumen in a coagulable state sometimes occurs in normal 
 excrements; it is, however, found in large quantity in the 
 evacuations in dysentery and in typhus (and not unfrequently 
 
 * Several analyses, showing the large quantity of fat occurring in the faeces 
 of diabetic patients, may be found in Simon's " Animal Chemistry," vol. ii. 
 pp. 377-79. 
 
THE F^CES. 199 
 
 in the fluid or semi-fluid stools which sometimes occur in 
 Bright's disease), and in lesser quantity in cholera.* 
 
 Epithelial structures occur in the stools in all cases of 
 diarrhoea. They are extremely abundant in the evacuations 
 in cholera. (See PL V.fig. 2.) 
 
 Cytoid corpuscles are abundant in the evacuations in 
 intestinal catarrh and in dysentery ; and are occasionally 
 observed in typhus and cholera. The glassy mucus which 
 sometimes occurs in roundish masses in catarrhal affections 
 of the large intestines is apparently secreted by the follicles 
 of the colon. 
 
 The intestinal evacuations have been especially studied in 
 typhus and cholera. 
 
 (182.) In typhus the stools are usually fluid, of a yellowish Faeces in 
 brown colour, an abominable smell, and an alkaline reaction. 
 On standing for some time they separate into a yellowish 
 sediment, consisting of flakes of undigested food, white 
 granules of about the size of a pin's head and probably 
 resulting from intestinal ulcers, epithelium, and often mucus, 
 and numerous crystals of phosphate of ammonia and mag- 
 nesia ; and an opaque supernatant fluid of a yellowish or pale 
 brown tint, generally containing albumen and a large quan- 
 tity of chloride of sodium. 
 
 In cholera the main peculiarities of the stools are, in 
 addition to the abundance of epithelium already referred to, 
 an extraordinary quantity of water, a little albumen, very 
 little biliary matter, and a large amount of salts, among 
 which the chloride of sodium preponderates to such an extent 
 as often to exceed in amount all the organic matters. These 
 evacuations contain only from 1'2 to 2*4- of solid constituents. 
 The addition of nitric acid gives rise to a rose-red tint in 
 
 * In testing the evacuations (especially in cholera) for albumen, we must 
 neutralise the fluid matters with acetic acid before boiling, as they usually have 
 an alkaline reaction. 
 
 o 4 
 
200 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Intestinal 
 concre- 
 tions. 
 
 these stools, which is often also observed in the evacuations in 
 typhus. 
 
 (183.) Intestinal concretions are rare in man and in car- 
 nivorous animals, but are not uncommon in herbivorous 
 animals. They usually consist of phosphate of ammonia and 
 magnesia with some phosphate and carbonate of lime, which 
 have deposited themselves round a fragment of undigested 
 food. They are of no special physiological interest.* 
 
 * Further information on intestinal concretions may be found in Vogel's 
 "Pathological Anatomy," London, 1847, pp. 375-381, and in Meckel von 
 Hemsbach, " Ueber die Concremente im thierischen Organismus," Berlin, 1856, 
 pp. 182-188. 
 
201 
 
 CHAPTER XL 
 
 THE BLOOD AND ITS ALLIES. 
 
 SECTION I. THE BLOOD. 
 
 (184.) THE blood, as it exists in the circulating system of The blood; 
 the higher animals, is a somewhat thick, viscid fluid, heavier characters, 
 than water, usually of a bright cherry-red colour (the arterial 
 blood being of a lighter red than the venous), and only very 
 slightly transparent. It undergoes a change immediately 
 after its removal from the body, becoming more thick and 
 gelatinous, and finally separating into two distinct parts, a 
 solid dense dark-red mass, termed the clot or crassamentum, 
 and a clear, pale yellow fluid, the serum. 
 
 The blood while still warm, has a peculiar odour, which is 
 rather stronger in man than in woman, and is much more 
 marked in some other animals than in man * ; and it is appa- 
 rently due to the presence of one of the volatile fatty acids 
 in combination with an alkali. 
 
 The specific gravity of human blood varies from 1*045 to Specific 
 1-075, the average being 1-055; in women it is somewhat giavl) * 
 lower than in men, in children less than in adults, and in 
 pregnancy it is somewhat diminished. 
 
 * Barruel's test is based on this circumstance. He maintained, in a memoir 
 published in 1829, that by the addition of a little sulphuric acid to blood he 
 could distinguish by the odour that was developed whether the blood was 
 taken from a man, woman, ox, horse, sheep, goat, dog, pig, rat, &c. The 
 experiments of Schmidt show, however, that Barruel's test is not so general in 
 its application, and that it only gives characteristic results with the blood of 
 the goat, sheep, and cat (Die Diagnostik verdachtiger Flecke in Criminal- 
 fallen, 1848). 
 
202 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 The temperature of the blood very slightly exceeds that of 
 the tissues of the body; in man the thermometer, when 
 inserted into a vein, seldom rises above 102 (Nasse). The 
 blood leaving the liver by the hepatic veins has a higher 
 temperature than the blood of any other part of the body.* 
 
 (185.) The coagulation of the blood may be divided into 
 three stages. In from two to five minutes after its discharge 
 from the body, the blood becomes viscid, tough, and almost 
 gelatinous on its surface. In from seven to fourteen minutes 
 the consistence has so far increased that the whole mass 
 assumes the form of the vessel in which it has been placed. 
 After the expiration of this time, we observe on the surface a 
 thin layer of colourless or pale yellow fluid, which is found 
 also to surround the sides and bottom of the clot ; this is the 
 serum, and its quantity increases as the fibrin on which the 
 coagulation of the blood depends continues to contract, 
 until at length, after from twelve to forty hours, the clot 
 attains its minimum volume, and no more serum is expressed. 
 The clot usually retains in a lessened size the shape of the 
 vessel in which the blood contracted. The lower part of the 
 clot is of a darker and the upper surface of a lighter red than 
 the blood itself. The blood of men coagulates more slowly 
 than that of women, and the clot is denser. Arterial blood 
 coagulates more rapidly than venous blood. Free access of 
 atmospheric air hastens coagulation. On shaking or stirring 
 (or as we generally term it, whipping) freshly drawn blood we 
 prevent the formation of one consistent clot, and the coagu- 
 lating substance, the fibrin, separates in yellow or reddish 
 flakes, while the fluid remains as red and opaque as coagulated 
 blood. 
 
 (186.) We are indebted to Malpighi (1666) for the dis- 
 covery that the blood is not a mere solution of various sub- 
 stances, that is to say, a homogeneous fluid, but an emulsion, 
 
 * Bernard, Lesons de Physiologic Experimentale appliquee a la Medecine, 
 1855, vol i. p. 201. 
 
THE BLOOD. 203 
 
 in which solid particles are suspended. Of these particles, by 
 very far the greatest number are the minute bodies known as 
 the red corpuscles, intermixed with which are the colourless 
 or lymph-corpuscles, a few fat-globules, and occasionally an 
 epithelial cell. 
 
 The red corpuscles (to which the terms blood-corpuscles Red cor- 
 and blood-discs are often applied) differ in size and form in pus 
 different kinds of animals. In all mammals, excepting the 
 camel, dromedary, and llama, they form thick, circular, 
 slightly biconcave discs, which are composed of a colourless 
 investing membrane, containing a thick fluid, which is red in 
 reflected, and yellow in transmitted light. (See PL V. fig. 3.) 
 One or more amorphous granules may sometimes be observed 
 in these blood-corpuscles, but it is now almost universally 
 admitted that they do not contain a true nucleus. 
 
 In the camel, dromedary, and llama, the blood-corpuscles 
 are elliptic and biconvex, resembling in these respects the 
 blood-corpuscles of birds, reptiles, and fishes. 
 
 Human blood-corpuscles have an average diameter of about 
 1-3 2 00th of an inch. The blood-corpuscles of the embryo 
 are a little larger than those of the same animal after the 
 establishment of respiration. In most mammals, excepting 
 the elephant, they are rather smaller than in man. By far 
 the largest corpuscles occur in the amphibia.* 
 
 Colourless or lymph-corpuscles are always present in the Colourless 
 blood, but occur in far less numbers than the red corpuscles, corpus 
 the ratio in which they stand in normal blood being about 
 1 :400. They are nearly spherical, larger than the red cor- 
 puscles and granular on their surface ; they contain one, or 
 sometimes two or more, rounded oval or reniform nuclei. 
 
 * Extensive tables of the measurement of the blood-corpuscles of different 
 animals are given in Gulliver's edition of Hewson's works (printed for the 
 Sydenham Society, 1846), pp. 237 244, in C. Schmidt's "Diagnostik verdach- 
 tiger Flecke in Criminalfallen," 1848 (at the end), and Milne Edwards's 
 "Leyons sur la Physiologic et 1'Anatomie Comparee de 1'Homme et des 
 Animaux," 1857, vol. i. pp. 83-90. 
 
204 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 From their being rich in fat and deficient in ferruginous 
 haematin, they are of lighter specific gravity than the red cor- 
 puscles ; hence we find them suspended in considerable num- 
 bers in the serum or accumulated on the surface of the clot.* 
 
 The fat globules and epithelial cells require no special 
 description. 
 
 (187.) The fluid in which the above described morphotic 
 elements are suspended has received the various names of 
 liquor sanguinis, plasma, and intercellular fluid ; in the cir- 
 culating blood it contains in solution not only all the solid 
 matters of the serum, but likewise the fibrin on which the 
 coagulation of the blood depends. 
 
 The clot or coagulum consists of the fibrin in a coagulated 
 state, of the blood-corpuscles which are enclosed in its meshes 
 in contracting, and of a certain amount of serum which 
 escapes the pressure of the contracting coagulated fibrin, and 
 moistens the interior. 
 
 The serum which gradually exudes during the contraction 
 of the clot has precisely the same composition whether we 
 examine the first or the last drops of the expressed fluid ; its 
 average specific gravity is 1*028. 
 
 The elements or constituents of the blood arrange them- 
 selves differently in the living and in the dead fluid. 
 
 Living blood = corpuscles -f- liquor sanguinis (= dissolved 
 fibrin + serum). 
 
 Dead blood = clot ( = coagulated fibrin + corpuscles) + 
 serum. 
 
 * Dr. Hirt, of Zittau, has recently published an elaborate memoir on this 
 subject. He found, in experiments made upon himself, that before breakfast 
 the white were to the red corpuscles as 1 : 1800 ; an hour after breakfast (the 
 breakfast hour being eight o'clock) as 1 : 700, and between eleven and one 
 o'clock as 1 : 1500. At one o'clock he dined, soon after which the white cor- 
 puscles became more abundant than even after breakfast, namely, as 1 : 400 ; 
 while two hours afterwards they fell to 1 : 1475. Shortly after supper (the 
 supper-hour being eight o'clock) they again rose to 1 :550, while by eleven 
 o'clock they again sunk to 1 : 1200. We thus see the close connection between 
 the digestive process and the number of the white corpuscles (Miiller's Arch. 
 1856, p. 174.). 
 
THE BLOOD. 
 
 205 
 
 (188.) It is self-evident from the preceding observations 
 that the corpuscles and their viscid fluid contents must be 
 very different in their composition from the liquor sanguinis 
 or the serum. 
 
 The following table (drawn up by Lehmann, and based 
 partly on his own and partly on Schmidt's analyses) shows at 
 a glance the differences between the composition of the 
 blood-corpuscles and that of the fluid in which they are 
 contained : 
 
 Chemical 
 composi- 
 tion of the 
 corpuscles, 
 liquor san- 
 guinis, and 
 blood. 
 
 1000 parts of blood- corpuscles 
 contain : 
 
 1000 parts of liquor sanguinis 
 contain: 
 
 Water. . . . 688-00 . . '. . , 902-90 
 
 Solid constituents . 312-00 ...... 97-10 
 
 Specific gravity 1-0885 .... 1-028 
 
 Hsematin . . . 16.75 Fibrin .... 4-05 
 
 Hsematocrystallin . .241-07 Albumen . . . 78-84 
 Cell-membranes . 41-15 
 
 Fat .... 2-31 * . v^';Q 7 . 1-72 
 
 Extractive matter . 2-60 . * '' V 3-94 
 Mineral substances 
 
 (excluding iron) . 8-12 8-55 
 
 Chlorine . . 1-686 . . ... . 3-644 
 
 Sulphuric acid . 0-066 0-115 
 
 Phosphoric acid 1-134 0-191 
 
 Potassium . . 3-328 0-323 
 
 Sodium " : -t ' . 1-052 3-341 
 
 Oxygen ' . ' .0-667 . . JV ^ '. 0-403 
 
 Phosphate of lime 0-1 14 0-311 
 
 Phosphate of 
 
 magnesia. . 0-073 ..... 0-222 
 
 The two following tables exhibit the composition of male 
 and female human blood. The analyses were made by 
 Schmidt and were employed by Lehmann in the con- 
 
206 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 struction of the preceding tables. The only modification 
 that I have introduced is to separate his hgematoglobulin 
 (or blood-casein, as Schmidt terms it) into hsematocrystallin 
 and cell-membranes in the proportions in which the two 
 latter substances normally stand to one another. 
 
 Man aged 25 Years. 1000 parts of Blood (Sp. Gr. 1-060) 
 
 contained : 
 
 513-02 of Blood-cells* + 486'98 of Plasma. 
 
 Water. . . .349-69 . * * 439-02 
 
 Solid residue . 163-33 . 47-96 
 
 Haematin . . 7*70 
 
 (including iron 0-512) 
 Haematocrystallin 127-54 
 Cell-membrane, fat, 
 and extractive 
 matters . . 24-35 
 Inorganic consti- 
 tuents (exclusive 
 of iron) . . 3-74 
 
 Consisting of: 
 
 Chloride of potassium 1-887 
 Chloride of sodium 
 
 Sulphate of potash 0-068 
 
 Phosphate of potash 1-202 
 
 Phosphate of soda 0-325 
 
 Soda . . . 0-175 
 
 Phosphate of lime 0-048 
 Phosphate of mag- 
 
 Fibrin . . , 
 
 Albumen, fat, and 
 extractive 
 matters 
 
 Consisting of: 
 
 nesia . 
 
 0-031 
 
 3-93 
 
 39-89 
 
 4-14 
 
 0-175 
 0-701 
 0-137 
 
 0-132 
 0-746 
 0-145 
 
 0-106 
 
 * As I have purposely excluded all complicated analytical details from this 
 volume, I must refer those who wish to ascertain how to determine the ratio of 
 the blood -cells to the plasma to Schmidt's investigations on the composition of 
 the blood in his " Charakteristik der Epidem. Cholera," 1850, pp. 16-19, or to 
 Lehmann's " Physiological Chemistry," vol. ii. pp. 219-221. 
 
THE BLOOD. 
 
 207 
 
 Woman * aged 30 Years. 1000 parts of Blood (Sp. Gr. 1 -050) 
 contained : 
 
 396-24 of Blood-cells 
 Water .... 272-56 
 Solid residue . 123-68 
 
 Hsematin . . 6-99 
 
 (including iron 0-489) 
 Haematocrystallin 95-01 
 Cell-membrane, fat, 
 and extractive 
 matters . . 18-13 
 Inorganic consti- 
 tuents (exclusive 
 of iron) . . 3-55 
 
 Consisting of : 
 
 Chloride of potassium 1 -353 
 Chloride of sodium 
 
 Sulphate of potash 0-062 
 
 Phosphate of potash 0-835 
 Phosphate of soda 
 
 Potash . . . 0-340 
 
 Soda. . . . 0-874 
 
 Earthy phosphates 0-086 
 
 60376 of Plasma. 
 
 . . 551-99 
 . 51-77 
 
 Fibrin . 
 
 Albumen, fat, and 
 extractive 
 matters . 
 
 Consisting of: 
 
 1-91 
 
 44-79 
 
 5-07 
 
 0-270 
 3-417 
 0-131 
 
 0-267 
 
 0-648 
 0-332 
 
 * Becquerel and Rodier have given the following general formula as repre- 
 senting the average composition of healthy human blood, as deduced from 
 twenty -two cases : 
 
 Water .... 
 Solid constituents 
 
 Blood-corpuscles 
 
 Albumen . . 
 
 Fibrin .... 
 
 Fatty matters . 
 
 Soluble salts . 
 
 Earthy phosphates . 
 
 Iron .... 
 
 Indefinite extractive matters 
 
 781-60 
 
 218-40 
 
 135-00 
 
 70-00 
 
 2-50 
 
 1-55 
 
 6*00 
 
 035 
 
 0-55 
 
 2-45 
 
208 PHYSIOLOGICAL CHEMISTRY. 
 
 From the preceding tables we at once perceive that not 
 only are certain constituents peculiar to the blood-cells and 
 to the plasma respectively (namely, haematin with its iron, 
 haematocrystallin, and cell-membranes to the former, and 
 fibrin and albumen to the latter), but that some of the con- 
 stituents common to both preponderate in a remarkable 
 degree in one or the other (namely, potassium and phosphoric 
 acid in the former and sodium and chlorine in the latter). 
 Arrange- (189.) In accordance with the arrangement adopted in the 
 subject! * C Preceding tables, we shall first consider the physical and 
 chemical properties of the blood-corpuscles, and then those of 
 the intercellular fluid or plasma, after which the differences 
 presented by the blood under various physiological conditions 
 and in various parts of the system ; the modifications impressed 
 upon this fluid by disease ; and the blood of the lower animals 
 will be duly noticed ; while we shall conclude with a few 
 remarks on one or two chemico-physiological points, as, for 
 instance, the quantity of blood contained in the body, the 
 functions of the blood-cells, &c. 
 
 The blood- (190.) The physical properties of the blood-corpuscles 
 physical exert a considerable influence on some of the changes which 
 characters. cer tai n physiological and pathological conditions impress 
 upon the blood. The simplest diffusion-experiment shows 
 that these blood-corpuscles are vesicles in which the con- 
 tents differ physically and chemically from the cell-wall : in 
 the intercellular fluid they maintain the form of biconcave 
 discs ; on the addition of water they become distended even to 
 bursting ; while solutions of neutral salts, sugar, or gum 
 cause them to collapse. Hence in the circulating blood there 
 are continuous endosmotic currents between the intercellular 
 fluid and the viscid red fluid which occupies the interior of 
 the blood-cells; and, as the former is more or less dense, so 
 do the vesicles tend to collapse or expand. Hence the specific 
 gravity of the blood-corpuscles is by no means constant, 
 increasing when more water is withdrawn from them than 
 
THE BLOOD. 209 
 
 from the intercellular fluid, and diminishing when the latter 
 becomes more than usually watery ; moreover, they become 
 specifically heavier after the abstraction of a portion of their 
 salts and ha3mato3rystallin, as occurs in the circulating blood 
 after repeated bleedings ; for the haematin (which is dense, 
 from its iron) is then retained in the corpuscles in excess, 
 and increases their weight (Lehmann*); and they become 
 specifically lighter when they contain an excess of fat in 
 the form of fine molecules, or when the blood is abnormally 
 aqueous. 
 
 In men the density may normally vary from 1*0885 to 
 1-0889, and in women from 1-0880 to 1-0886. The highest 
 density that has been observed is in cholera, where it has 
 reached 1*1027, and the lowest in dropsy, where it has fallen 
 to 1*0819; hence its ascending is much greater than its 
 descending range. 
 
 The tendency to sink which the blood-corpuscles possess is 
 doubtless mainly due to their specific gravity, but it seems to 
 be also to a certain degree dependent on another physical 
 property which they exhibit, that, namely, of arranging them- 
 selves like rolls of coins with their flat surfaces in contact 
 (see Plate V. Jig. 4). This nummular arrangement (as it 
 has been termed) never occurs in quite fresh blood; it is 
 usually most distinctly seen, under the microscope, after 
 partial evaporation of the water of the blood. The ten- 
 dency of the red corpuscles to arrange themselves in this 
 manner has been referred, especially by Henle, to an 
 augmented viscidity of the intercellular fluid induced by an 
 excess of fibrin or albumen ; and by Nasse to a peculiar 
 viscidity in the cell-walls themselves : of these two views the 
 latter is the more probable. 
 
 In connection with the sinking tendency of the corpuscles Variations 
 
 Nasse finds that it differs very considerably in different g^lng 
 
 tendency. 
 
 * Handbuch dcr Physiol. Cliem. 1854, p. 103. 
 P 
 
210 PHYSIOLOGICAL CHEMISTRY. 
 
 animals ; they sink most rapidly in the horse, most slowly in 
 the pig. The serum of horses' blood is certainly very viscid, 
 but this viscidity cannot be the cause of the slow sinking, 
 because the corpuscles of horses' blood sink just as rapidly 
 in the serum of the blood of other animals, and because 
 further the blood-corpuscles of other animals do not sink 
 with greater rapidity in the serum of horses' blood. The 
 fact that the corpuscles of horses' blood contain less fat 
 than those of most other animals may have something to 
 do with the rapid sinking. 
 
 The corpuscles sink more rapidly in inflammatory than in 
 healthy blood, the former being richer in carbonic acid and 
 rather poorer in albumen than the latter ; as, moreover, they 
 sink with equal rapidity in defibrinated inflammatory blood, 
 the excess of fibrin which exists in this blood can have nothing 
 to do with the sinking tendency. 
 
 (191.) The colour of the blood is dependent on several 
 conjoined causes, amongst which may be especially men- 
 tioned, (1) the form of the corpuscles, (2) the thickness of 
 their walls, (3) the admixture of strongly refracting or re- 
 flecting molecules, and (4) certain chemical relations. 
 
 1. Contracted biconcave corpuscles must act the part of 
 minute concave mirrors, and by their reflection must com- 
 municate a light colour to the mass of the blood; while 
 corpuscles distended by endosmosis into a convex shape 
 must in a corresponding manner scatter and disperse the 
 light and thus render the colour darker. In accordance with 
 this view we find that all substances which, by abstracting 
 water from the corpuscles, render them more biconcave, as, 
 for instance, solutions of neutral salts*, of sugar, &c., and which 
 exert no disintegrating action on the blood, communicate to 
 
 * The following are some of the salts producing these effects : the sulphates 
 and nitrates of potash and soda, chlorate of potash, phosphate, carbonate and 
 bicarbonate of soda, ferrocyanide, iodide, and sulphocyanide of potassium, 
 biborate of soda, hydrochlorate of ammonia, &c. 
 
THE BLOOD. 211 
 
 it a lighter tint; while substances which distend the cor- 
 puscles, such as water, ether, and diluted organic acids, 
 communicate a deep purple tint to the blood. We must not, 
 however, conclude that the concavity of the corpuscles is the 
 main cause of the light colour of the blood, for the blood of 
 the amphibia which contains biconvex corpuscles (which 
 cannot be rendered biconcave) also becomes of a light tint 
 on the addition of a solution of the neutral salts, or of sugar. 
 
 2. Scherer, who has very carefully studied the influence of 
 the form of the corpuscles on the colour of the blood, has 
 shown that the change of form must necessarily be accom- 
 panied by an alteration in the thickness of the cell-walls, 
 which must likewise modify the tint of the blood. If the 
 corpuscles are collapsed the cell-walls will be relatively thick, 
 and will conceal the pigment in the interior ; while if they are 
 distended their cell-walls will be relatively thin, and will 
 allow the dark red colouring matter to shine through them, 
 just as the colour of any dark red fluid is modified according 
 as it is seen through a thick or a thin ground-glass vessel. 
 On this account all substances which cause the cell-wall to 
 burst, or which dissolve it, as, for instance, acetic acid, the 
 alkalies, &c., communicate a dark red colour to the blood 
 in consequence of the dissolved hsematin mixing with the 
 intercellular fluid. 
 
 From observations of Harless on the large biconvex blood- 
 corpuscles of the frog, it appears that oxygen causes a con- 
 traction and carbonic acid an expansion of these bodies; 
 hence a plausible explanation has been given of the difference 
 in colour between arterial and venous blood. 
 
 3. There are often physical relations not directly acting on 
 the blood-corpuscles which may modify the colour of the 
 whole blood. Scherer showed that the addition of milk or of 
 powdered gypsum made the blood of a lighter red tint, and a 
 similar effect is produced when the blood contains a great 
 excess of colourless corpuscles (as often occurs in anaemia and 
 
 p 2 
 
212 PHYSIOLOGIC AX CHEMISTRY. 
 
 always in leucaemia) or when it abounds in fat-globules (as in 
 the case of confirmed drunkards). 
 
 4. The observations of Harless, to which reference has 
 already been made, indicate that although the primary action 
 of oxygen and carbonic acid is mechanical, these gases like- 
 wise exert a chemical influence on the blood-corpuscles : thus 
 he found, for instance, that when we allow these gases to act 
 alternately on the red corpuscles they become gradually 
 destroyed, the destruction being usually completed after the 
 ninth or tenth time. 
 
 The observations of Lehmann and others show that in a 
 similar manner that action of saline substances, &c., although 
 primarily mechanical, is also chemical. But whether these 
 substances, and more especially the gases, in addition to 
 acting on the cell-walls, extend their influence to the contents 
 and especially to the pigment, is a question which is not very 
 easily answered. It is true that as yet we are unacquainted 
 with any special compounds of blood-pigment with oxygen 
 or with carbonic acid, but the following facts lead to the 
 belief that such compounds exist. 
 
 (192.) "Arterial blood, or blood which has been impreg- 
 nated with oxygen, appears, in thin layers, of a beautiful 
 scarlet colour, from a bright yellowish red to a dun colour ; 
 while venous blood or blood impregnated with carbonic acid, 
 hydrogen, or nitrogen, appears, when seen in thin layers, of a 
 purple colour; while in extremely thin layers it appears 
 green. The latter, therefore, exhibits dichromatism, which is 
 not the case with the former. Since artificially prepared 
 hsematin is monochromatic after the addition of acids, and 
 dichromatic after being treated with alkalies, the difference in 
 colour, effected by the action of oxygen or carbonic acid, can 
 scarcely be referred to purely mechanical conditions. 
 
 " Blood which has been so diluted with water that no red 
 corpuscles can be any longer recognised by the microscope, 
 always becomes somewhat lighter coloured by oxygen and 
 
THE BLOOD. 213 
 
 darker by carbonic acid. The dark red solution of pure 
 hsematocrystallin also becomes of a somewhat lighter tint by 
 oxygen, but of a still darker red by carbonic acid. That 
 these gases also combine chemically with other protein-bodies 
 is apparent from the fact that a solution of the globulin of 
 the crystalline lens is entirely precipitated by carbonic acid, 
 and that the precipitate is redissolved by the action of 
 oxygen. On the other hand, the metameric haematocrystallin 
 when treated with acetic acid and alkaline salts exhibits the 
 opposite reaction, being precipitated from its solution by 
 oxygen and redissolved by carbonic acid. 
 
 " After the preceding remarks it is almost unnecessary 
 to observe that dilute acids exert a chemical action on the 
 cell-walls of the blood-corpuscles ; but those salts also, which 
 at first produce contraction of the blood-cells and thus cause 
 the colour of the blood to become lighter, exert a gradual 
 destructive action on the cell-walls, so that the blood-cor- 
 puscles not only become altered in their form, but after a 
 longer or shorter time are entirely destroyed, and, as a 
 natural consequence, the colour of the blood, which was at 
 first light red, passes into a deep dark red. The alkaline 
 sulphates and nitrates maintain the vermilion colour of the 
 blood for a considerable time ; but with alkaline carbonates 
 and hydrochlorate of ammonia the dark red tint very rapidly 
 supervenes." * 
 
 (193.) The last physical property of the blood-corpuscles 
 requiring notice is, that on filtering the blood they, for the 
 most part, pass through the filtering paper. They, however, 
 lose this property if concentrated solutions of the sulphate of 
 soda or potash be previously added to the blood, and in this 
 way a quantitative analysis of the blood-corpuscles has been 
 
 * Lehmann, Handbuch d. Physiol. Chem. Leipz. 1854, p. 107. The dis- 
 covery of the dichroism (or dichromatism) of venous blood (referred to in the 
 above quotation) is due to Briicke (Sitzungsbericht d. Wiener Akademie, 
 vol. xi. p. 1070). 
 
 P 3 
 
214 PHYSIOLOGICAL CHEMISTRY. 
 
 attempted. Dumas recommends that in order to check the 
 clogging of the filter (which soon ensues) a stream of oxygen 
 should be continuously passed into the fluid lying in the 
 filter, while at the same time the solution of the alkaline 
 sulphate should constantly drop into it. 
 
 (194.) The chemical characters of the blood-corpuscles now 
 claim our attention. We shall consider first the cell-mem- 
 brane, and secondly the fluid contents of the corpuscles. 
 The cell- The cell-membrane, which formerly was erroneously sup- 
 of the red posed to consist of fibrin, and more recently of Mulder's 
 corpuscles, binoxide o f protein, forms in a state of purity and while still 
 moist, a grayish-white viscid mass, which swells and assumes 
 a gelatinous appearance in acetic acid and dilute alkalies, 
 does not dissolve in nitre-water even after prolonged digestion 
 at 100 F., contains no sulphur, and behaves towards nitric 
 and hydrochloric acids like a protein-body.* 
 
 Two circumstances render it probable that the substance of 
 the cell-walls has not always a precisely identical composition.! 
 In the first place the addition of much water, or of ether, or 
 acetic acid, affects the corpuscles of every kind of blood very 
 unequally ; some of them, probably the oldest, disappearing 
 on the addition of very little water, while others (which we 
 consider to be the youngest cells) do not appear changed even 
 after great dilution. Secondly, no addition of water can 
 cause the entire disappearance of the cells of the blood of the 
 hepatic veins ; the cells sinking to the bottom and forming 
 a considerable deposit in the diluted blood. 
 
 * Lehmann's experiments on this substance are recorded in his Physiolog. 
 Chemistry (Cav. Ed.) vol. ii. p. 184. In his most recent work (Handbucli d. 
 Physiol. Chem., 1854, p. 108) he recommends the following as the best mode 
 of obtaining the substance of the cell-membranes. Hsematocrystallin prepared 
 from the fluid of the blood-cells and containing many cell-membranes enclosed 
 in its crystals, must be first rinsed with very diluted spirit till nitrate of silver 
 ceases to yield any reaction, and then be treated with distilled water, which 
 dissolves the pure haematocrystallin but does not act upon the membrane-sub- 
 stance, which, after extraction with alcohol and ether for the removal of any 
 traces of fat, may be regarded as pure. 
 
 f Handbuch d. Physiol. Chem. 1854, p. 109. 
 
THE BLOOD. 215 
 
 (195.) The ratio in which the moist blood-cells stand to Katio of 
 the plasma or intercellular fluid seems to be very variable ceii^th 
 even in normal blood. According to Lehmann the moist plasma, 
 cells in the case of adults amount on an average to 51'2 of 
 the blood, the limits being 47*2 and 54-2. In the only 
 analysis of a healthy woman's blood given by Schmidt *, the 
 cells, however, fall far below Lehmann's limit, amounting 
 only to 39*6^. The blood of women, especially during 
 pregnancy, is somewhat poorer in cells than that of men. 
 Repeated venesections and other losses of the animal "fluids 
 are said to diminish their number, but Schmidt's investigations 
 of the blood of cholera patients do not bear out this assertion. 
 The blood of the pig is richer in corpuscles than that of any 
 other mammal. In the amphibians the number of corpuscles 
 is relatively smaller than in any other vertebrated animals. 
 
 Several observers have recently attempted to determine 
 the number of red corpuscles in a given volume of healthy 
 human blood. Vierordt found that on an average 1 cubic 
 millimetre (which = 0-1055 or about l-9th of a cubic line) of 
 normal blood, obtained by pricking the finger, contained 
 5,055,000 corpuscles ; Welckerf fixes the number at 4,600,000; 
 and Cramer { at 4,726,400. 
 
 (196.) Hsematin and globulin have been, until very recently, Chemical 
 regarded as the main constituents of the contents of the t uen ts of 
 blood-corpuscles, the globulin being supposed to be identical the blood - 
 with the substance of that name obtained from the crystalline 
 lens of the eye. The recent investigations of Funke, Leh- 
 mann, and others have, however, shown that the substance 
 which is associated with hsematin in the blood-cells differs Hsemato- 
 essentially from true globulin. It is sufficient here to indi- crys ' 
 cate two leading points of difference. Grlobulin cannot be 
 
 * Charakteristik d. Epidem, Cholera, 1850, p. 33. 
 f Arch. d. Verein f. ges. Arb. vol. i. p. 161. 
 
 J Quoted by Henle in his Keport on the Progress of Anatomy during the 
 year 1855, in Canstatt's Jahresbericht. Wiirzburg, 1856, vol. i. p. 34. 
 
 p 4 
 
216 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 obtained in a crystalline form, and is completely precipitated 
 from its aqueous solution by a stream of carbonic acid, while 
 the protein-body contained in the blood-cells is distinguished 
 from all similar bodies by its crystallisability, and it is not 
 precipitable by carbonic acid. The leading characteristics of 
 this substance, to which the term hcematocrystallin is applied, 
 have been already described in p. 116. The moist blood- 
 corpuscles contain from 18 to 26 of dry hsematocrystallin, 
 while its amount in the whole blood ranges from 9 to 12-g-. 
 Hasmatin. The insoluble highly ferruginous hsematin, which has been 
 described in p. 94, does not occur in that condition in the 
 blood, but is merely a product of the metamorphosis of the 
 true blood-pigment. It occurs in the blood in a soluble form, 
 and is so intimately associated with the hsematocrystallin that 
 it cannot be obtained in a pure condition in a soluble state. 
 On the assumption that the soluble pigment existing in the 
 cells contains the same amount of iron as the artificially pre- 
 pared hsematin, namely 6'93f , the blood-corpuscles of an adult 
 man must contain 16 or 17-jj- of this constituent. 
 
 There seems reason to believe that when there is an excess 
 of water in the blood the haematin occurs in relatively greater 
 quantity in the blood-corpuscles. 
 
 A considerable quantity of the fatty matter contained in 
 the blood is accumulated in the corpuscles, which in their 
 dry state contain, according to Lehmann, from 2 to 3 of 
 fat, consisting of a mixture of margarin, olein, margarate, 
 oleate, and glycero-phosphate of potash, and cholesterin. 
 
 The cells in venous blood contain more fat than those in 
 arterial blood. 
 
 The so-called extractive matters, whose chemical nature is 
 still most imperfectly understood, occur in the blood-cells, 
 although less abundantly than in the plasma. In the solid 
 residue of the cells these extractive matters scarcely average 
 6^, while in the solid residue of the serum of the same blood 
 they amount to about 8. 
 
 Fats. 
 
 Extractive 
 matters. 
 
THE BLOOD. 217 
 
 In addition to acid phosphates or conjugated phosphoric 
 acids, Lehmann infers that the blood-cells must likewise con- 
 tain a nitrogenous non-crystallisable acid ; for if the crystal- 
 line substance of the .blood be coagulated by heat from its 
 watery solution, the filtered fluid has an acid reaction, and, in 
 addition to acid earthy phosphates, contains this acid whose 
 characters are that it is not crystallisable, that it reddens 
 litmus, that with bases it forms salts which are soluble in 
 water and for the most part in alcohol, and that, on heating, it 
 develops a gelatin-like odour and leaves a bulky carbonaceous 
 residue difficult of combustion. 
 
 We are indebted to the laborious and accurate investiga- Salts, 
 tions of Schmidt for a knowledge of the fact that the collective 
 mineral constituents of the blood-cells are by no means identical 
 with those which we find in the serum, although some salts are 
 common (in different proportions) to both. He has discovered 
 that the fluid of the blood-cells (that is to say, the water con- 
 tained in the blood-corpuscles) contains, in addition to organic 
 matters, a great preponderance of phosphates and potash salts, 
 so that the phosphate of potash and the greater part of the 
 chloride of potassium belong to the blood-cells, while the 
 chloride of sodium, with a little chloride of potassium and 
 phosphate of soda, belongs to the plasma. In the latter the 
 organic matters are combined solely with soda, while in 
 the blood-cells the fatty acids and the ha3mato-globulin are 
 associated with potash as well as with soda. 
 
 In analysing a specimen of blood which contained 396*24 Prepon- 
 of blood-cells and 603-76 of intercellular fluid, Schmidt found potassium 
 1-353 of chloride of potassium and 0-835 of phosphate of 
 potash in the former, and 3-417 of chloride of sodium, with 
 0-267 of phosphate of soda and 0-270 of chloride of potassium 
 in the latter. 
 
 The following table, calculated for 100 parts of inorganic 
 matters, gives the chief results of Schmidt's observations : 
 
218 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 
 Blood-cells. 
 
 Plasma. 
 
 Blood-cells. 
 
 Plasma. 
 
 Genus 
 
 
 
 
 
 
 K. 
 
 Na. 
 
 K. 
 
 Na. 
 
 P0 5 . 
 
 Cl. 
 
 P0 5 . 
 
 Cl. 
 
 Man (Mean of "I 
 8 analyses)./ 
 
 40-89 
 
 9-71 
 
 5-19 
 
 37-74 
 
 17-64 
 
 21-00 
 
 6-08 
 
 40-68 
 
 Dog ... 
 
 6-05 
 
 36-17 
 
 3-25 
 
 39-68 
 
 22-12 
 
 24-88 
 
 6-65 
 
 37-31 
 
 Cat ... 
 
 7-85 
 
 35-02 
 
 5-17 
 
 37-64 
 
 1362 
 
 27-59 
 
 7-27 
 
 41-70 
 
 Sheep . 
 
 14-57 
 
 38-07 
 
 6-56 
 
 38-56 
 
 895 
 
 27-21 
 
 3-56 
 
 40-89 
 
 Goat . . . 
 
 14-98* 
 
 37-41* 
 
 3-55 
 
 37-89 
 
 9-41 
 
 31-73 
 
 5-90 
 
 4041 
 
 These results have received further confirmation from 
 Weber's f comparative analyses of the serum and of the 
 clot of horses' blood, while they strengthen the view pro- 
 pounded several years ago by Nasse, that the phosphates are 
 most abundant in the blood of those animals in which the 
 corpuscles are most numerous (as in the pig, goose, and hen), 
 and most scanty in those animals in which the opposite con- 
 dition holds (as in the sheep and the goat), and that the 
 phosphates are mainly contained in the corpuscles. 
 
 The differences between the salts of the blood-cells and of 
 the plasma are most obvious in human blood ; in the car- 
 nivora the difference is most distinctly seen in reference to 
 the phosphoric acid, while in the herbivora it is most marked 
 in reference to the potassium. 
 
 The corpuscles of arterial blood are invariably richer in 
 salts than those of venous blood. 
 
 Earthy The earthy phosphates occur in the blood-cells in con- 
 
 siderable quantity, although not so abundantly by about 
 one-half as in the plasma ; Schmidt found that in the former 
 they amounted to 0-2 1 8 p. m., while in the latter they reached 
 0-550 p. m. 
 
 * In Schmidt's original table (Charakt. d. Epidera. Cholera, p. 14) these 
 figures are reversed, but it is far more probable that there should be an 
 accidental misplacement of the figures than that they should differ so 
 enormously from the corresponding numbers in the sheep. 
 
 f Pogg. Ann., 1850, vol. Ixxxi. pp. 99115. 
 
THE BLOOD. 219 
 
 The iron of the blood pertains almost solely to the haematin 
 of the blood-cells. The blood-corpuscles obtained from the 
 hepatic veins contain less iron than those from the portal 
 vein ; and, according to Schmidt, there is an excess of iron in 
 the blood-cells in hydrsemic conditions of the system, whence 
 he concludes that in these cases the cells have become 
 poorer in hsematocrystallin, and hence relatively richer in 
 hsematin. 
 
 In dry blood-corpuscles Schmidt found 0-4348$ of iron in 
 man, 0'509$ in the ox, 0-448$ in the pig, and 0-329$ in the 
 hen. 
 
 (197.) The gases of the blood, carbonic acid, nitrogen, and Gases, 
 oxygen, are almost entirely contained in the blood-corpuscles, 
 as is shown by the fact that whipped blood, which contains 
 almost all the corpuscles, possesses a very considerable power 
 of absorbing gases, while the serum scarcely absorbs more 
 than water. It appears from the experiments of Magnus on 
 the blood of the calf, the ox, and the horse, that defibrinated 
 blood will absorb 1'5 times (or 150$) its own volume of car- 
 bonic acid, but only from 10 to 13$ of its volume of oxygen, 
 while it does not absorb more nitrogen than pure water. The 
 combinations which these gases form with the constituents of 
 the blood are somewhat unstable, as is obvious from the facts 
 that the greater amount of the gas can be again extracted 
 from the blood in vacuo, and that one kind of gas will expel 
 another. Nitrogen occurs in nearly equal quantity in venous 
 and in arterial blood, the amount ranging, according to 
 Magnus, from 1-7 to 3-3$ (by volume). In arterial blood 
 there is relatively, but not positively, more oxygen than in 
 venous blood ; the ratio of the oxygen to the carbonic acid 
 being as 6 : 16 in the former, and as 4 : 16 in the latter. The 
 oxygen in the blood varies from 10 to 12-5-9- (Magnus), while 
 the carbonic acid has been estimated at 66$ in arterial and 
 78$ (by volume) in venous blood (Magendie). 
 
 The view maintained by Magnus that the gases in question 
 
220 PHYSIOLOGICAL CHEMISTRY. 
 
 enter into no chemical combination with the constituents of 
 the blood either in passing to or from the tissues of the body, 
 but form merely a physical mixture with the circulating fluid, 
 is no longer generally accepted by chemists. If, for example, 
 the oxygen were only mechanically absorbed and there were 
 no chemical union, the blood could only take up the same 
 quantity as an equal volume of water, namely 0-92 5-g-, 
 whereas in reality it absorbs from 10 to 13-g-; and, further, 
 the quantity of gases taken up would be proportional to 
 the pressure, which is not the case. This greater force of 
 absorption in the blood can only depend upon certain of its 
 constituents, and principally, as we have shown, upon the 
 corpuscles; only from l-14th to 1-1 1th of the oxygen which 
 is absorbed by the blood can be -absorbed mechanically, that 
 is to say, by the water, or can consequently exist free in the 
 blood; the large amount of remaining oxygen (10-llths at 
 the lowest calculation) must be fixed by the blood-cells 
 through the agency of some chemical attraction. Finally, 
 in the main constituent of the blood-corpuscles, the hsemato- 
 crystallin, we have an organic body which possesses a special 
 affinity for these gases, and in which one gas can expel an- 
 other.* 
 
 Unstable compounds of this nature are not very rare in 
 chemistry. Carbonate of soda absorbs a considerable quantity 
 of carbonic acid, forming the bicarbonate ; and the same is 
 the case with phosphate of soda ; this carbonic acid may, 
 however, be expelled either by another gas, as, for instance, 
 
 * For further and more detailed arguments in favour of the view advocated 
 in the text namely, that the absorbed oxygen, or the greater part of it, enters 
 into chemical combination with one or more blood-constituents I must refer 
 to a long foot-note to p. 332 of Liebig's Letters on Chemistry, 3rd edition, 
 1851; to pp. 521 525 of the third volume of my translation of Lehmann's 
 Physiological Chemistry, 1854; and to memoirs by Dr. Harley "On the Con- 
 dition of the Oxygen absorbed into the Blood during Respiration," in Proc. 
 Hoy. Soc. for April 17th, 1856, and by Meyer "On the Gases of the Blood," 
 in Phil. Mag. 1857, vol. xiv. pp. 263268. 
 
THE BLOOD. 221 
 
 oxygen, or by greatly reducing the atmospheric pressure : and 
 we have already pointed out (p. 115) that the globulin of the 
 lens shares this property with these salts. 
 
 In further support of this view it may be urged that 
 other gases, as, for instance, carbonic oxide, nitrous oxide, 
 arseniuretted hydrogen, &c., exert an obvious chemical action 
 on the corpuscles, when well agitated with the blood. 
 
 (198.) Before proceeding to the consideration of the inter- 
 cellular fluid we must briefly notice other morphotic elements, 
 which, in addition to the red corpuscles, are found suspended 
 in the blood : these are the white or colourless corpuscles and 
 the fibrinous flakes. 
 
 It is now almost universally admitted that the colourless Colourless 
 corpuscles of the blood are perfectly identical with the bodies coipufi 
 occurring in lymph, chyle, mucus, and pus, to which the general 
 term " cytoid corpuscles " has been applied. These corpuscles 
 are nearly spherical (see Plate V. fig. 5), with a diameter 
 of from *004 to *005 // , and differ from the red corpuscles in 
 not being elastic ; their investing membrane is granular, and 
 is always so viscid that the corpuscles possess a decided ten- 
 dency to adhere in groups. The contents of these cells 
 consist of an albuminous solution in which there are sus- 
 pended extremely minute granules, together with a single, 
 double, or triple nucleus, which may be either smooth or 
 granular. Water causes the corpuscles to swell, and, by 
 attenuating the cell-wall, renders the nucleus more visible ; 
 but the best method of exhibiting the nucleus distinctly is 
 by the addition of acetic acid, which dissolves the cell-wall. 
 
 We usually find it stated that the ratio of colourless to red Ratio of 
 corpuscles is about 1:10. It is, however, usually much below to C thVred 
 this. Bonders and Moleschott* estimate it at 1:373, their corpuscles, 
 results being based on the examination of blood from seven 
 
 * On this subject, see also Kolliker's Manual of Human Histology, translated 
 by Busk and Huxley, vol. ii. p. 330, and Milne Edwards's Legons sur la Phy- 
 siologic et 1'Anatomie Coinparee, vol. i. p. 350. 
 
222 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Fibrinous 
 flakes. 
 
 Consti- 
 tuents of 
 the plasma. 
 
 Fibrin. 
 
 Process 
 of coagu- 
 lation. 
 
 individuals at different periods of life. They find moreover 
 that food rich in albumen increases the quantity of the 
 colourless cells, and that there is a similar excess during the 
 periods of menstruation and of pregnancy. 
 
 The blood of the splenic vein is specially rich in these 
 colourless cells (Funke), and the blood of the hepatic veins 
 contains them more abundantly than that of the portal vein. 
 They have been observed in excess after repeated venesec- 
 tions (Kemak) and in cases of pneumonia and tuberculosis ; 
 and they are especially abundant in pyaemia and still more so 
 in leucaemia, when they often stand to the red corpuscles in 
 the ratio of 1 : 3. 
 
 The so-called fibrinous flakes were originally discovered 
 and named by H. Nasse.* The researches of Doderlein, 
 Bruch, and others have, however, clearly shown that these 
 flakes are not composed of fibrin. They seem chemically 
 to resemble horny tissue, and are mostly epithelial cells, 
 partly derived from the inner coat of the blood-vessels and 
 partly (as Bruch maintains) from the face of the observer. 
 
 (199.) The intercellular fluid or plasma contains the fibrin 
 in solution as well as the constituents of the serum. We 
 shall commence with the consideration of the fibrin, because 
 in the first place, it is the most highly organised substance in 
 the plasma ; and secondly, because, from its separation from 
 the blood, by spontaneous coagulation, in the clot, it is 
 closely associated with the blood-corpuscles. 
 
 (200.) The chemical characters of fibrin having been suffi- 
 ciently described in an earlier part of the volume (see p. 109), 
 we shall confine our remarks mainly to the subject of its co- 
 agulation. 
 
 The form in which the fibrin coagulates can be best ob- 
 served with the microscope when we place between the slide 
 and cover-glass a drop of fluid free from blood-cells, ob- 
 
 * Miiller's Archiv. 1841, p. 439. 
 
THE BLOOD. 223 
 
 tained from blood whose corpuscles have slightly sunk below 
 the surface before it began to gelatinise. We first of all ob- 
 serve, scattered over the field, isolated molecular granules, 
 from which extremely fine straight filaments very soon pro- 
 ject, extending like rays from each point, but not forming 
 regular star-like masses, such as we observe in certain crys- 
 tals. These filaments become gradually elongated, and fre- 
 quently cross one another, so as finally to resemble a tangled 
 cobweb ; and this net-work soon becomes so dense as almost 
 to conceal the colourless corpuscles which are embedded in it. 
 As fibrin, when we examine it in a drop of dried blood, exhi- 
 bits a laminated appearance, many observers are of opinion 
 that it separates in lamellae during coagulation, and that the 
 fibrous appearance is due solely to the duplication or over- 
 lapping of these lamellae. 
 
 (201.) Chemists and physiologists have long endeavoured Cause of 
 to ascertain the agency by which the fibrin is held in solution 
 in the circulating blood, and the cause of its separation in a 
 solid form in the blood that has been abstracted from the 
 body. Until very recently (1856) the view generally adopted 
 was that the oxygen of the atmospheric air induced such a 
 change in the dissolved fibrin that it became insoluble in the 
 alkaline plasma. The researches of Dr. Richardson have, 
 however, shown that the presence of oxygen is not necessary 
 to secure coagulation ; in fact, that blood will coagulate as 
 rapidly in the presence of nitrogen alone, or 1 hydrogen, or 
 other gas, as in the presence of oxygen, and more rapidly in 
 a vacuum than under other circumstances. These observa- 
 tions are corroborated by reference to the experiments of Sir 
 H. Davy, Dr. John Davy, and Sir C. Scudamore. Reasoning 
 on these and other experiments, Dr. Richardson has come to 
 the definite conclusion that coagulation is due to the escape 
 of some volatile agent. This view had also been held by 
 Scudamore and Polli, who imagined that carbonic acid gas 
 was the eliminated principle. To put the question beyond 
 
224 PHYSIOLOGICAL CHEMISTRY. 
 
 doubt, Dr. Richardson collected the vapour from a large 
 quantity of blood, and then drove it through a small quantity 
 of blood newly drawn into a test tube. So long as the blood- 
 vapour was slowly passing through the blood, coagulation was 
 suspended. Having settled the question thus far, this phy- 
 siologist proceeded to examine what agents were evolved in 
 the blood-vapour. He found carbonic acid gas and nitrogen 
 were thus evolved ; but on driving these gases through blood, 
 they had no power in holding the blood fluid. They were, 
 therefore, excluded from the argument. Something else had 
 to be looked for. Remembering that the blood was alkaline, 
 and that a salt of ammonia was present in blood, he sought 
 for the volatile alkali in blood-vapour, and definitely found 
 it. By holding a microscope glass moistened with pure hy- 
 drochloric acid over blood while coagulating, he obtained, on 
 drying the glass, unmistakable crystals of hydrochlorate of 
 ammonia. He also drove the vapour of blood through dilute 
 hydrochloric acid, and by the chloride of platinum test ob- 
 tained the crystals of the double salt of chloride of ammo- 
 nium and platinum. Next, on adding ammonia, or neutral 
 carbonate of ammonia, to blood, he discovered that newly 
 drawn blood could be thus kept fluid for lengths of time, 
 varying according to the amount of ammonia added, and to 
 the conditions under which the blood was placed, i. e., as 
 regarded the possibility of an escape of ammonia, and the 
 surrounding temperature. Finally, he succeeded in redis- 
 solving blood-clot in serum alkalinified with ammonia, and 
 in re-inducing coagulation on gently driving off the volatile 
 alkali. 
 
 The quantity of ammonia necessary to hold blood tempo- 
 rarily fluid is exceedingly small. Dr. Richardson computes 
 that, in the living and healthy body, with the blood sealed 
 up in its containing vessels and in steady motion, one part of 
 ammonia is all-sufficient to sustain the fluidity of 3000 parts 
 of blood, or even more. 
 
THE BLOOD. 225 
 
 The time of coagulation of healthy human blood varies 
 according to external circumstances. At a temperature of 
 60, the process is generally complete in three minutes. Be- 
 low this point, the process is retarded ; above, it is propor- 
 tionally quickened. 
 
 In the dead body, if the death take place rapidly, if the 
 blood at the moment of death is fluid, and if the circulatory 
 system is entire, coagulation is often postponed for many 
 hours, but occurs in a few minutes when the body is laid 
 open, and the blood is exposed to the air. 
 
 (202.) The period at which coagulation commences and is Circum- 
 completed is modified by various physiological and patholo- modifying 
 gical conditions. Strong agitation of the blood, whether by ] 
 shaking or stirring, promotes the separation of the fibrin, lation 
 The free access of atmospheric air or oxygen has the same 
 effect, and hence blood coagulates more rapidly in flat and 
 open than in deep and narrow vessels ; for the same reason it 
 coagulates more rapidly when it trickles slowly from a vein 
 than when it flows in a full stream. Blood which is rich in 
 carbonic acid coagulates less rapidly than when the contrary 
 is the case ; hence in cyanosis and in inflammatory disorders 
 it is slow in coagulating. Blood containing an excess of 
 water, or to which water has been added in small quantity, 
 coagulates rapidly, while large quantities of water (more than 
 twice the bulk of the blood) tend to retard coagulation ; 
 hence we find that, after repeated venesections and in an- 
 aemia, the blood coagulates more rapidly than in healthy per- 
 sons. Little is known with accuracy regarding the action 
 of salts on the coagulation, except that dilute solutions of the 
 alkaline sulphates, nitrates, hydrochlorates, carbonates, and 
 acetates, retard that process. As, in most of the experiments 
 on this subject, no attention has been paid to the degree of 
 dilution of the saline solution, or to the quantity of the solu- 
 tion employed, the results are of little value. Viscid solutions 
 
 Q 
 
226 PHYSIOLOGICAL CHEMISTRY. 
 
 of indifferent organic substances, such as albumen, casein, and 
 sugar, retard the coagulation of the blood. The influence of 
 temperature on the coagulation has not yet been sufficiently 
 studied ; we know, however, that, when blood is frozen before 
 or during coagulation, it coagulates after thawing, just as if 
 it had not been frozen. It appears very doubtful whether the 
 quantity of fibrin exerts any influence on the period of co- 
 agulation. In the present imperfect state of our knowledge 
 in reference to the blood, we are unable to explain why this 
 fluid does not coagulate in the bodies of persons who have 
 been struck by lightning, have been hanged, or who have 
 died from asphyxia or narcotic poisoning, while it coagulates 
 very rapidly in cases of plague, and after the infliction of 
 venomous bites. 
 
 Consist- (203.) The consistence of the clot is liable to great varia- 
 
 cloT f the ti ns > which* however, are not dependent, as was long sup- 
 posed, on any peculiarities in the chemical composition of the 
 fibrin, but upon certain mechanical influences, of which the 
 most important is the relative quantities of the blood-cor- 
 puscles and of the fibrin. When the number of corpuscles is 
 small in relation to the quantity of fibrin, the latter contracts 
 more closely, and a dense firm clot is formed ; while, if the 
 corpuscles are much in excess, the fibrin seldom coagulates 
 so firmly, and thus we have a soft friable clot. As the lower 
 part of the clot contains an excess of corpuscles, it is always 
 softer and looser in texture than the upper part. For a 
 similar reason, the clot in the blood of plethoric persons is 
 large and soft ; while in that of chlorotic patients it is small 
 and firm. An excess of water diminishes the consistence of 
 the clot, as has been found both by direct experiments (the 
 addition of water) and by observations on morbid hydraemic 
 blood. Carbonic acid and salts which impede coagulation, 
 give rise to a soft clot ; thus, while highly oxygenised, bright 
 red blood forms a dense elastic clot, the over-carbonised blood 
 
THE BLOOD. 227 
 
 of cyanotic and asphyxiated persons yields a very soft gela- 
 tinous coagulum. 
 
 (204.) The form of the clot mainly depends upon the Form of 
 shape of the vessel in which the coagulation of the blood t; 
 takes place ; although there are other modifying circum- 
 stances, amongst which we must especially mention the period 
 of coagulation of the fibrin, and the sinking tendency of the 
 blood-corpuscles. The clot is often observed to be covered 
 on its surface with a thicker or thinner layer of tough fibrin 
 (the buffy coat or inflammatory crust), concave in the centre, 
 with a raised margin, presenting what is termed a cupped 
 appearance. The appearance known as the buffy coat is Buffy coat, 
 caused by the corpuscles sinking below the surface of the 
 fluid- before the fibrin begins to separate and coagulate : from 
 the absence of corpuscles at and near the surface, the fibrin, 
 which in due time coagulates there, will be of a whitish grey 
 colour, and will contract more firmly than the under portion 
 in which corpuscles are embedded, and hence the cup-shaped 
 depression with the raised margin. There are also various 
 accessory conditions which favour the production of the buffy 
 coat, as for instance 1. The form of the vessel in which the 
 blood coagulates. In a high narrow vessel the corpuscles 
 sooner sink below the level of the fluid than in a wide shallow 
 one, and thus leave a part of the fibrin to coagulate without 
 them ; on this account, inflammatory blood is often found to 
 yield no buffy coat in a flat vessel, whilst, on the other hand, 
 blood which is considered of a non-inflammatory -character 
 often exhibits a buffy coat, if received in a narrow cylinder. 
 2. The number of corpuscles is not without influence. When 
 the corpuscles are relatively few in number, and their sinking 
 tendency is considerable, a buffy coat will be readily formed. 
 On this account it is formed after repeated venesections, in 
 anaemia, pregnancy, &c.* 3. An excess of fibrin was formerly 
 regarded as the main cause of the formation of this coat ; and 
 
 Q2 
 
228 PHYSIOLOGICAL CHEMISTRY. 
 
 as the increase of fibrin was considered proportional to the 
 progress of inflammation, this buffy coat received the name 
 of the inflammatory crust. The quantity of fibrin doubtless 
 exerts some influence on the thickness of the buffy coat; 
 but that it is not the principal cause of this coat, is obvious 
 from the fact that inflammatory blood which is very rich in 
 fibrin often forms no crust, while blood that is poor in fibrin 
 may in many chronic cases present it. 
 
 Hitherto we have assumed that the corpuscles have sunk 
 rapidly, and that the fibrin has coagulated slowly. Some- 
 times, however, the converse relations are observed ; and then 
 we not only have no buffed or cupped appearance, but, in 
 addition to a dense clot, we have a red sediment of corpuscles. 
 Henle explains this by assuming that the fibrin coagulates 
 and becomes contracted before the corpuscles had arranged 
 themselves in the nummular form, and that, on the contrac- 
 tion of the gelatinised fibrin, a large number of the isolated 
 corpuscles are expressed, which at first render the serum turbid 
 and red, but soon deposit themselves in a sediment. 
 Quantity (205.) The quantity of fibrin in the blood in various phy- 
 
 *' fibrin in siological and pathological conditions is sufficiently noticed 
 
 in pp. 110, 237, 239, 240, and 244. 
 
 The serum. (206.) The serum, after the separation of the fibrin and the 
 blood-corpuscles, often contains certain undissolved particles in 
 suspension, which communicate to it a milky or, at all events, 
 an opalescent appearance. This turbidity of the serum has 
 been observed in blood taken some hours after a meal ; (Leh- 
 mann, however, failed to observe anything of this kind either 
 in carnivorous or herbivorous animals ;) it has likewise been 
 noticed after prolonged fasting, during pregnancy, and very 
 frequently, but not invariably, in the blood of drunkards. In 
 these cases, the turbidity is due to the presence of suspended 
 fat, as may readily be seen by a microscopic examination, or 
 by shaking the serum with ether. 
 
THE BLOOD. 229 
 
 A variety of turbid serum sometimes occurs in the blood 
 in inflammatory conditions. The turbidity in this case de- 
 pends upon the presence of very small dark molecules of a 
 protein-body, supposed by Zimmermann to be a variety of 
 fibrin, but regarded by Scherer and Lehmann as separated 
 albumen. As in these cases the serum is only very faintly 
 alkaline, and the turbidity disappears on the addition of a 
 neutral alkali salt, it is most probable that the album inate of 
 soda in the blood has been deprived of some of its alkali, and 
 that a portion of the albumen, thus freed from its soda, sepa- 
 rates in the molecular form. 
 
 (207.) The quantity of water in the serum usually stands Quantity 
 in a direct ratio to the quantity of water in the whole blood. i n it. 
 All observers agree that the serum of woman's blood is more 
 watery than that of man's blood. Schmidt, one of our most 
 accurate chemists, found 90'884-g- of water in the latter, and 
 91*715- in the former. In pregnancy the serum is especially 
 rich in water. 
 
 It is uncertain whether copious draughts of fluid occasion 
 a temporary augmentation of water in the serum, in conse- 
 quence of the rapidity with which an excess of water is 
 removed from the blood ; but there is no doubt that, in the 
 absence of proper nourishment for any length of time, we 
 have a diminution of the solid constituents of the serum, and 
 consequently a relative increase of water. Since in most 
 diseases comparatively little food is taken, and the nutritive 
 function is commonly more or less impaired, the blood in 
 these cases is, with a few exceptions, richer in water than in 
 the normal state. 
 
 A decided and absolute diminution of the water in the 
 serum and in the blood generally is only observed in cholera. 
 
 The serum of arterial blood is richer in water than that of 
 venous blood. On comparing the blood of the temporal 
 artery of a horse with that of the external jugular vein, Leh- 
 
 Q 3 
 
230 
 
 PHYSIOLOGICAL CHEMISTKT. 
 
 mann found that the relative quantities of water in 100 parts 
 of serum were 89-333 and 86-222. The serum of the portal 
 blood contains more water than that of any other venous 
 blood, and in this respect differs remarkably from the blood 
 of the hepatic veins. 
 
 The quantity of water in the serum is found to vary con- 
 siderably in the blood of different animals the serum of 
 amphibians contains the largest amount of water, and that of 
 birds a larger quantity than that of mammals. 
 
 (208.) The most important constituent of the serum is 
 albumen the raw material from which all the other protein- 
 bodies, and probably all the nitrogenous tissues of the animal 
 body, are elaborated. Its quantity varies in healthy serum 
 from 7*9 to 9-8J, and in the collective blood from 6 -3 to 
 
 In most diseases, especially in scurvy, malaria, puerperal 
 fever, dysentery, Bright's disease, and dropsy from organic 
 disease of the heart or liver, the quantity of albumen in the 
 serum is diminished ; while in intermittent fevers, after dras- 
 tic purgatives, and in cholera, it is increased. 
 
 Becquerel and Rodier believe that they have established 
 the fact, that the transudation of albuminous fluids (or, in 
 other words, dropsy) begins when the albumen in the serum 
 sinks below 6^-. 
 
 The process of digestion is accompanied by an augmenta- 
 tion of the albumen in the blood. Arterial blood contains 
 less albumen than venous blood ; while Lehmann found 
 11-428-g- of albumen in the venous blood-serum of the horse, 
 he found only 9'2l7g in the corresponding arterial serum. 
 Of venous blood, the portal blood is the poorest, and the 
 hepatic blood the richest, in albumen. Human blood con- 
 tains rather more albumen than that of most mammals. 
 
 (209.) Many observers (Panum, Moleschott, Stas, &c.) 
 regard casein as a normal constituent of the serum, and 
 
THE BLOOD. 231 
 
 maintain that it is especially abundant in the blood, during 
 pregnancy, and in the puerperal state. There can be no 
 doubt that a substance strongly resembling casein does occur 
 in the serum, and has even been determined quantitatively 
 (see p. 114); but as we have already shown (p. 106), certain 
 modifications of albumen can hardly be distinguished from 
 casein. 
 
 (210.) The fat contained in the serum consists chiefly of Fats, 
 stearates, margarates, and oleates, with a little cholesterin : 
 the serolin, which was formerly supposed to occur there, being 
 apparently only a mixture of the crystallisable parts of the 
 above fats. The phosphorised fats which (as has been already 
 mentioned) are found in the corpuscles, do not occur in the 
 serum. The quantity of fat in the normal serum is very 
 variable, but about 0*2-- seems to be the average quantity. 
 During digestion the quantity of fat in the serum is in- 
 creased. The blood- serum of women usually contains more 
 fat than that of men. The serum of arterial blood contains 
 less fat than that of venous blood, the relative numbers in 
 the case of the horse being, according to Lehmann, 0*264-^ 
 and 0*393^. The greatest quantity of fat is found in the 
 serum of the portal blood ; while that of the hepatic veins 
 contains less than that of the portal blood, but much more 
 than the serum of jugular blood. 
 
 From the investigations of Becquerel and Eodier it appears 
 that the quantity of fat, and especially of cholesterin, is in- 
 creased at the beginning of every acute disease; it is likewise 
 increased in chronic affections of the liver, in Bright's 
 disease, in tuberculosis, and in cholera. 
 
 (211.) The extractive matters of the serum are formed by Extractive 
 a mixture of various known and unknown organic bodies. matteiu 
 Their amount is liable to great fluctuations, ranging, ac- 
 cording to Lehmann, from 0'25 to 0-42-g-, and when we 
 consider how many things are vaguely included in this 
 
 Q 4 
 
232 PHYSIOLOGICAL CHEMISTRY. 
 
 term, and how their amount must in a great measure vary 
 with the rapidity of the metamorphosis of the tissues, we 
 need not be surprised at the irregularity of their quantity. 
 Nasse has found more extractive matters in the blood of 
 children and young animals than in the blood of adults 
 an observation which accords with what Scherer has noticed 
 in the urine. Arterial blood contains more extractive matters 
 than venous blood. Of venous blood, that of the hepatic 
 veins contains more than that of the portal vein, and the 
 latter more than that of the jugular. 
 
 The only diseases in which the extractive matters have 
 been observed to be much increased are puerperal fever 
 and scurvy. 
 
 We have recently succeeded in detecting (in small quan- 
 ties) various known substances which formerly passed un- 
 recognised among the extractive matters : these are sugar 
 (see p. 88), urea* (see p. 46), creatine (see p. 36), creatinine 
 (see p. 37), hypoxanthine in the blood of the splenic vein (see 
 p. 50), hippuric acid (see p. 59), and probably formic, acetic, 
 and lactic acids (see pp. 11, 21). (That formic and lactic 
 acids exist in the blood seems obvious from the fact that the 
 sweat contains an abundance of the former and the muscles 
 of the latter. All three acids have moreover been found in 
 the blood of the splenic vein.) There is also an odorous 
 
 * The researches of M. Picard on the determination of the urea in the blood 
 are briefly alluded to in a note to p. 46. Since the sheet containing that note 
 was printed, I have obtained fuller information regarding his investigations on 
 this point. The following are some of the results. In the blood of healthy 
 men he found 0'0177g, 00142g, and 0-0165 of urea; and in that of healthy 
 women, 0-01 53g and 0'0169g The blood of a woman in the sixth month of 
 pregnancy contained 0'0260, that of a woman at the ninth month 0-01 13g; 
 and that of a woman two days after delivery 0*01 8 7g. The blood of a man who 
 had fasted for some time contained 0*01 7 7g, and five hours after a meal of 
 animal food, 0-0175g. Placental blood contained 0'062g, 0'028, and 0'027g. 
 The blood of the carotid artery of a horse contained 0'0293g, while that of the 
 external jugular vein contained 0'035. 
 
THE BLOOD. 233 
 
 principle which has not yet been isolated, but which is probably 
 a volatile fatty acid ; the odour which is very characteristic in 
 the blood of some animals (as, for instance, the goat, the 
 sheep, and the cat) is most distinctly developed when we 
 mix the blood with rather more than its volume of sulphuric 
 acid (see p. 201). 
 
 In different varieties of morbid blood we not only find in 
 the extractive matters certain of the above-named substances 
 in excess, but likewise bile-pigment and the biliary acids 
 (sometimes even when there is no apparent disease of the 
 liver), hypoxanthine and glutin (in leucsemic blood), and 
 oxalic and uric acids in gout (see p. 67). 
 
 (212.) It appears from the best analyses which we possess Mineral 
 of the ash of the serum, that it is composed of: tuents" 
 
 Chloride of sodium 61-087 
 
 Chloride of potassium . . . '" . 4-054 
 
 Carbonate of soda . /' ; . . / 28-880 
 
 . Phosphate of soda (21NaO,P0 5 ) . . ' -V ' \ 3-195 
 
 Sulphate of potash. .' . V . v '"' ; ^ 2-784 
 
 100-000 
 
 The sulphate of potash in the above table is a product of 
 incineration, and so probably to a considerable extent is the 
 carbonate of soda. The blood-serum of man contains rather 
 more salts than that of woman (the relative numbers having 
 been estimated at 8'8-g- and 8 !--), and that of adults more 
 than that of children. 
 
 From the examination of the blood of different kinds of 
 animals living on food of the most opposite character, it ap- 
 pears that the nature of the diet does not materially affect 
 the amount of the saline constituents. The investigations of 
 Nasse and Poggiale show that the blood of cats, goats, sheep, 
 and calves contains the most salts, then that of birds, then 
 that of man and the pig ; while the blood of dogs and rabbits 
 
234 PHYSIOLOGICAL CHEMISTRY. 
 
 contains the smallest quantity. The prolonged use of an 
 excess of salt seems, however, to render the blood richer in 
 chloride of sodium.* 
 
 Arterial serum is somewhat richer in salts than venous serum, 
 if we except the serum of the portal blood. After prolonged 
 or repeated venesection, the blood which is drawn last con- 
 tains more salts than that which first escapes. 
 
 In severe inflammatory affections, and especially in cholera, 
 the saline constituents of the serum are much diminished; while 
 in the acute exanthemata, in typhus, dysentery, malignant 
 intermittent fevers, scurvy, Bright's disease, and in all varie- 
 ties of dropsy and hydrsemia, they are considerably increased. 
 
 Silica has hitherto only been detected in the blood of birds ; 
 but that it must occur in minute quantity in the blood of 
 man and other mammals, seems evident from the fact that it 
 is a constituent of the hair. 
 
 Carbonate of ammonia is commonly supposed only to exist 
 in the blood in typhus and other diseases of a low type, in 
 cholera, and in those disorders in which urea accumulates in 
 the blood. 
 
 (213.) We now proceed to notice the differences which the 
 blood presents in its chemical composition under various phy- 
 siological conditions. 
 
 The blood of women is of rather a lighter tint than that of 
 man, is of lower specific gravity, developes a less intense 
 odour of sweat on the addition of sulphuric acid (see p. 201), 
 and contains more water and fewer blood-corpuscles ; as there 
 is a preponderance of serum in female blood, the latter con- 
 tains more albumen, fats, and extractive matters than male 
 
 * Plouviez took daily 10 grammes (about 2-5 drachms') of salt with his food 
 for three months. At the commencement of the experiment the salt in 1000 
 parts of his blood amounted to 9'33, of which 4-40 were chloride of sodium ; 
 while at the conclusion they amounted to 1 1*84, of which 6'10 were chloride of 
 sodium. (Compt. rend., 1847, vol. xxv. pp. 110113.) 
 
THE BLOOD. 235 
 
 blood ; although the serum of female blood contains less salts 
 than that of male blood, the actual blood contains more salts in 
 the female than in the male sex. (See Tables in pp. 2 06 , 207.) 
 
 In pregnancy*, the blood is usually of a darker colour than Of preg- 
 in the non-pregnant state ; it has a low specific gravity, being 
 rich in water, and deficient in red corpuscles ; the fibrin is 
 relatively increased, which accounts for the small compact 
 clot and the buffy coat which are often observed during preg- 
 nancy. The serum contains less than the normal quantity of 
 albumen ; but the casein-like substance is found in aug- 
 mented quantity in the serum towards the end of pregnancy 
 and in the puerperal state. (See p. 114.) 
 
 The blood of young children is richer in solid constituents, Of age. 
 especially in red corpuscles and extractive matters, but poorer 
 in fibrin and salts, than the blood of adults. 
 
 In advanced age, and in the female sex, from the period 
 when menstruation ceases, the blood becomes relatively poor 
 both in red corpuscles and albumen; the cholesterin is, how- 
 ever, somewhat increased (Becquerel and Rodier). 
 
 During digestion the blood becomes richer in solid consti- Of diges- 
 tuents ; there is a marked augmentation of the colourless cor- 
 puscles, and a slight excess of red corpuscles, albumen, fat, 
 and salts ; the fibrin is slower than usual in coagulating ; and, 
 from the excess of fat, the serum is not unfrequently turbid. 
 
 Prolonged starvation, depraved nutrition, and excessive 
 loss of the animal fluids, produce very similar effects on the 
 blood ; the corpuscles are diminished, while the plasma be- 
 
 * Nasse, who has examined the blood of thirty-six women during the last 
 three months of pregnancy, arrives at the following conclusions. The blood 
 of pregnant women differs from that of women in the non-pregnant state, 
 (1.) in its lower specific gravity (and this applies equally to the serum); 
 (2.) in its containing more than the normal quantity of fibrin ; (3.) in its 
 exhibiting in more than three-fourths of the cases a buffy coat ; and (4.) in 
 the number of lymph-corpuscles being often much increased. (Arch, des 
 Vereins f. gemeinsch. Arb., 1854, vol. i. pp. 351373.) 
 
236 PHYSIOLOGICAL CHEMISTRY. 
 
 comes more watery, and poorer in albumen and other organic 
 constituents, but richer in salts. We are indebted to C. 
 Schmidt* for the discovery of the important law, that the 
 diminution of albumen in the blood is always associated 
 with a corresponding augmentation of salts. 
 
 Difference (214.) The composition of the blood varies considerably, 
 arterial 1 according to the part of the circulating system from which 
 
 blood and fa^, fj u j(j j s obtained. Lehmann t has recently investigated 
 
 the blood 
 
 of the this subject more fully than any preceding chemist, and we 
 
 a'mfsmaller sna ^ endeavour to extract from his memoir his most im- 
 veins. portant conclusions, and to incorporate them with the results 
 previously known. 
 
 From a very elaborate table, containing the numerical 
 results of fourteen analyses of the blood of five horses the 
 blood of various veins (the external abdominal, the cephalic, 
 the digital, and the jugular veins, and the inferior vena cava) 
 being contrasted with the arterial blood of the same animal 
 he draws the following inferences : 
 
 (a.) No definite conclusion could be drawn from the relative 
 proportions of the serum and the clot; indeed, no inference 
 could ever be deduced regarding the relative degrees of con- 
 
 * Charakteristik der Epidem. Cholera, Leipzig, 1850, p. 108. 
 
 f Untersuchungen iiber die Constitution des Bluts verschiedener Gefasse 
 und den Zuckergehalt derselben insbesondere, in the Ber. d. k. Sachs. Ges. 
 d. Wiss. zu Leipzig. Math. Phys. Classe, 1855, pp.87 122. The main 
 points discussed in this elaborate memoir are, (1.) On the differences of the blood 
 of different veins as -compared with arterial blood, based on fourteen analyses 
 of horses' blood ; (2.) On the quantity of sugar in the blood of different 
 vessels ; (3.) Comparative analyses of the blood of the hepatic and portal veins 
 of dogs fed on animal diet ; (4.) On the relative quantities of fat in the blood of 
 the hepatic and portal veins ; (5.) On the quantity of sugar in the blood of the 
 hepatic and portal veins of dogs in various physiological conditions ; (6.) On 
 the sugar that has been assumed (by Igguier) to exist in the blood of the 
 portal vein after an animal diet ; (7.) On the chemical composition of various 
 parts of the blood collected from the portal vein ; and (8.) Do either the portal 
 blood or the contents of the stomach or intestine contain any substance, after 
 the use of an animal diet, that can by any known methods be readily converted 
 into sugar ? 
 
* 
 THE BLOOD. 237 
 
 tractility of the clot, because the blood, even though obtained 
 as rapidly as possible after the death of the animal, occurred 
 in a gelatinous or semi-coagulated state. 
 
 (6.) On comparing the fibrin of the blood of the smaller 
 veins with that of arterial blood, we find it more abundant 
 (in the ratio of 6 or even 6-5 -fe to 4 -5%)* in the venous than 
 in the arterial blood. If we might draw a conclusion from so 
 small a number of cases, it would be that the fibrin is chiefly 
 formed in the capillary system ; we must, however, not over- 
 look the fact, that in consequence of the diminution of the 
 number of corpuscles in the capillaries the augmentation of 
 the fibrin is in part only a relative one. 
 
 (c.) Two analyses of the blood of the jugular vein lead us 
 merely to the unsatisfactory conclusion that this blood either 
 differs in no material respect from arterial blood, or that it 
 is liable to very considerable fluctuations in its composition. 
 
 (d.) The blood of the vena cava was examined three times, 
 twice before the hepatic veins had poured their contents into 
 it. Even in these two last cases, before it had been mixed 
 with the non-fibrinous blood of the hepatic veins, its quantity 
 of fibrin, as compared with that of arterial blood, was very 
 small, being in about the ratio of 1 to 2 a result that is the 
 more striking, in consequence of the richness of the blood of 
 the small veins in fibrin. The most probable explanation is, 
 that the fibrin is mainly formed in the blood in its course 
 through the arteries, that its quantity is considerably in- 
 creased in the capillaries, where there is still an abundance of 
 oxygen, and that it finally undergoes disintegration in the 
 larger veins. 
 
 (e.) If we compare the solid residue of the serum of these 
 different kinds of blood, we find that in the case of the vena 
 cava there was, on an average, an excess of solid constituents, 
 
 * By the symbol 9 we indicate " per mille." 
 
238 PHYSIOLOGICAL CHEMISTRY. 
 
 and that in the jugular and the smaller veins there was a 
 diminution, as compared with arterial serum. The quantity 
 of salts in the serum of arterial blood is almost always 
 greater than that in venous serum, but the augmentation is 
 only relative, being due to the decomposition and disinte- 
 gration of organic materials in the lungs. Although it is 
 principally the extractive matters which undergo this fate, a 
 portion of the albumen also disappears in the passage of the 
 blood through the lungs, and is probably converted into 
 fibrin and other substances. (On an average we find 2-g- 
 less of albumen in the solid residue of arterial serum than in 
 that of venous serum.) 
 
 (/.) The relative quantities of water and of the blood- 
 corpuscles in the different kinds of blood were found by 
 Lehmann to yield an additional confirmation of the law 
 established by Becquerel and Rodier, that the amount of 
 water in the blood usually stands in an inverse ratio to the 
 quantity of corpuscles. The blood of the smaller veins con- 
 stantly yielded more water and fewer corpuscles (on an 
 average about 6^- of each) than arterial blood ; similarly, in 
 the blood of the vena cava behind the openings of the hepatic 
 veins there were found less corpuscles by about 2$ than in 
 arterial blood ; and it was only in the case in which the blood 
 was drawn from the thoracic portion of that vein that it was 
 found to be richer in blood-cells than arterial blood (in the 
 ratio of 13*9 to 8'2) a result in complete accordance with 
 the fact previously established by Lehmann *, that the blood 
 of -the hepatic veins is richer in corpuscles than that of any 
 other vessel. 
 
 Portal (215.) Portal blood is very much influenced in its compo- 
 
 I0dt sition by the digestive process. During digestion, especially 
 
 * Einige vergleichende Analysen des Blutes der Pfortaden und der Le- 
 bervenen, in the Ber. d. k. Sachs. Ges. d. Wiss. zu Leipzig. Math. Phys. 
 Classe, 1851, p. 131. 
 
THE BLOOD. 239 
 
 if the animal has been drinking, it is rich in water and inter- 
 cellular fluid and poor in corpuscles; while the fibrin is 
 slightly augmented, the albumen, extractive matters, and 
 salts are moderately increased, and the fat still more so : the 
 fibrin at this period presents no peculiarities, but when 
 digestion is not going on, it possesses very slight contractility 
 and forms an exceedingly friable clot. 
 
 As compared with the blood of the jugular vein, the portal 
 blood is poor in blood-cells and in solid constituents gene- 
 rally. The cells are commonly described as irregular in shape, 
 and appearing as if they were undergoing disintegration. In 
 his latest memoir* on this subject, Lehmann, however, ex- 
 pressly states that neither in the portal blood of the horse nor 
 of the dog could he detect any abnormality in the form of 
 the red corpuscles, and that they in no way differed from the 
 corpuscles of the jugular or other veins : moreover, he found 
 colourless corpuscles in the blood of both these animals (the 
 existence of which in portal blood was denied by Simon f), 
 and in both these points he is confirmed by Funke.J The 
 blood-corpuscles are richer in hoematin and poorer in hsemato- 
 globulin than those of jugular blood, and contain double the 
 amount of fat. The quantity of fibrin is much smaller, but 
 it presents no peculiar quality except that it contains an ex- 
 cess of fat. Further, the albumen of the serum is much 
 diminished, but there is an augmentation of the fat, extractive 
 matters, and salts. No sugar is present unless the animal has 
 been living on amylaceous food, when it is found in very 
 small quantity. 
 
 * Ber. d. k. Sachs. Ges. d. Wiss. Math. Phys. Classe, 1855, p. 99. 
 
 f Animal Chemistry with reference to the Physiology and Pathology of 
 Man. London, 1845 (Printed for the Sydenham Society), vol. i. p. 202. 
 
 if Funke's edition of Wagner's Lehrbuch d. speciellen Physiologic. Leipz. 
 1854. p. 104. 
 
 In two dogs fed for two days on boiled potatoes, Lehmann only found 
 traces of sugar in 100 parts of the solid residue of the portal blood ; while in 
 
240 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Blood of 
 
 Blood of 
 the splenic 
 
 (216). The blood of the hepatic veins contains far more 
 cons tituents than that of the portal vein or any other 
 vessel. (In the case of three dogs whose portal and hepatic 
 blood was analysed by Lehmann, the latter was on an average 
 6-3 richer in solid constituents than the former.) It is 
 remarkably rich in corpuscles, both white and red, exceeding 
 the portal blood in this respect by more than 6-g-. The white 
 corpuscles occur in various forms and sizes. The red cells 
 collect in groups of a distinct violet colour, and present a 
 greater resistance to the action of water than the corpuscles of 
 any other blood : they are poorer in hsematin (or at all events 
 in iron, the iron of the solid residue of the clot being to that 
 of portal blood in the average ratio of 35 to 22) and in fat, 
 but richer in extractive matters. The intercellular fluid of 
 this blood contains no fibrin (consequently there is no coagu- 
 lation), less albumen and fat, and far less salts than the blood 
 of any other vessel ; but it contains such an excess of ex- 
 tractive matters that its solid constituents exceed those of any 
 other blood. This blood is likewise distinguished for the 
 abundance of sugar which it contains. This sugar, which is 
 formed in the liver, gradually diminishes with the distance 
 from the point of opening of the hepatic veins into the vena 
 cava till it finally disappears, under ordinary circumstances, 
 in the pulmonary circulation. 
 
 (217.) In its microscopical characters the blood of the 
 A 
 
 splenic vein closely resembles that of the hepatic veins. 
 Funke,* who has carefully examined this blood in the horse, 
 the dog, the ox, and in man, states that the red corpuscles in 
 these two kinds of blood resemble each other in their minute- 
 ness, in their more than usually spherical shape, in their 
 
 two horses fed on bran, hay, and straw the quantities were 0-055 and 0-0052 
 respectively. Poggiale, however, finds a larger amount of sugar in the portal 
 blood of animals fed on amylaceous food. (See Bernard's " Le9ons de Phy- 
 siologic," &c. Paris, 1855, vol. i. p. 498.) 
 * Op. cit. p. 117. 
 
THE BLOOD. 241 
 
 accumulating in heaps, and not assuming the nummular 
 arrangement, and in the resistance which most of them offer 
 to the destructive action of water, and some even to the action 
 of acetic acid. The colourless cells are very abundant, often 
 even more so than in hepatic blood, sometimes amounting to 
 one-fourth of the total number : they do not lie uniformly 
 scattered over the field, but are accumulated in large round 
 heaps, which often enclose red cells ; on the addition of acetic 
 acid the presence of one or more nuclei is often revealed. 
 Granular cells are not unfrequently seen in this blood, espe- 
 cially in horses ; and blood-corpuscle-containing cells have 
 been often seen in it by Kolliker and Ecker *, occasionally by 
 Mr. Gray, and once by Funke. In addition to the above 
 varieties of cells, Mr. Gray directs attention to the -almost 
 constant existence of numerous pigment granules, or masses, 
 or rod-shaped crystals, which either exist free or are con- 
 tained in cells. The pigment granules are of a dark black 
 or dark reddish brown colour, while the rod-like bodies are of 
 a red or yellowish red colour. 
 
 The red cells of the blood are remarkable for the facility 
 with which their contents crystallise ; it is only necessary to 
 allow splenic venous blood to stand exposed to- the air and to 
 light to obtain the crystals described in p. 116 ; it was thus 
 that Funke made his discovery of hsematocrystallin. 
 
 The only analyses of the blood of the splenic vein are 
 those of Beclard, Funke f, and Gray.J The chief point 
 established by Beclard's analyses is that the blood of the 
 splenic vein contains less blood-corpuscles than that of other 
 veins. Funke's researches by no means confirm Beclard's 
 view. The main difference detected by him between the 
 blood entering and leaving the spleen is that the latter is 
 
 * Zeitsch. f. rat/Med. vol. vi. p. 261. 
 | Ib. (New Series), vol. i. pp. 172218. 
 
 J On the Structure and Uses of the Spleen. London, 1854, p. 147. 
 
 R 
 
242 PHYSIOLOGICAL CHEMISTRY. 
 
 always considerably poorer in fibrin than the former, there 
 often being hardly any traces of this substance in the blood 
 of the splenic vein ; moreover, a small portion of the salts 
 which had belonged to the blood-cells was always found in 
 the intercellular fluid. The results obtained by Mr. Gray 
 from a very large number of analyses of horses' blood, show 
 that the blood emerging from the spleen presents the follow- 
 ing marked and constant peculiarities. It contains less solid 
 matter than arterial or other venous blood, the solid residue 
 in 1000 parts of splenic venous blood being to that in the 
 same quantity of arterial blood as 187-1 to 239. It contains 
 far less blood-globules ; while the average amount (the mean 
 of ten experiments) was 88 -5-^, the corresponding amount in 
 arterial blood was 162-2^-; the greatest diminution of the 
 blood-corpuscles occurred about sixteen hours after the diges- 
 tion of food, when the amount was only 27'93o- 5 -, while during 
 digestion the amount was above 100-^-. The average amount 
 of fibrin in splenic venous blood is double that of arterial 
 blood ; while the former contains 6 '4-^-, the latter only con- 
 tains 2-26 ; and the fat is fully as much or rather more aug- 
 mented. The albumen is increased ; in ten experiments on 
 this blood the average amount of this substance- was 60^-, 
 while in arterial blood it was only 37-2-^-. The amount of 
 iron which is contained in the blood emerging from the 
 spleen is considerably increased as compared either with arte- 
 rial or jugular venous blood, and this is an important fact in 
 connexion with the diminution of the number of the red cor- 
 puscles in the same blood. Lastly, a highly important pecu- 
 liarity is the deep reddish brown colour of the serum, which 
 depends upon the large amount of free hsematin contained in 
 solution. 
 
 Scherer* has analysed the parenchymatous juice of the 
 
 * Verhand. d. phys.-med. Ges. zu Wurzburg, 1852, vol. ii. p. 298. 
 
THE BLOOD. 243 
 
 spleen, which obviously must consist chiefly of blood, with 
 an admixture of lymph and of the fluid permeating the tra- 
 becular tissue and the coats of the vessels. He found in it a 
 new nitrogenous crystallisable body, which he named lienine 
 (but which he has since discovered to be identical with leucose), 
 hypoxanthine, an albuminous body rich in iron, a large quan- 
 tity of iron in combination apparently with acetic and lactic 
 acids, highly carboniferous pigments very similar to those 
 occurring in tlie urine and muscular juice, and uric, lactic, 
 acetic, formic, and butyric acids. In consequence of this in- 
 vestigation, Funke sought for hypoxanthine and uric acids in 
 the blood of the splenic vein ; he failed, however, to detect 
 any traces of either of these bodies *, nor did he find either 
 pigment or iron in the serum. 
 
 (218.) Menstrual blood contains no true fibrin; it separates Menstrual 
 into a colourless alkaline serum and a red sediment of blood- 
 corpuscles, intermixed with which are numerous colourless 
 cells. It contains about 16 of solid constituents, f 
 
 (219.) The blood of the placental vessels contains, accord- Placental 
 ing to Stasf, a deficiency of albumen and fibrin, but a great 
 excess of serum-casein ; it is stated also to contain an appre- 
 ciable quantity of urea (see note to p. 232). 
 
 (220.) Eepeated venesections diminish the specific gravity Influence 
 of the blood, render its colour lighter, cause it to coagulate section. 
 earlier, but not so firmly as in the natural state, diminish the 
 red corpuscles, and at the same time render them relatively 
 
 * Although we shall advert more fully to the subject in treating of the 
 glandular juices, we may here mention that Mr. Gray (and his colleague, 
 Dr. Noad, who materially assisted him in his analyses) failed in ever detecting 
 either hypoxanthine or uric acid in the juice of the spleen ; while Cloetta, and 
 subsequently Gorup-Besanez (Ann. d. Ch. u. Pharm. 1856, vol. xcviii. p. 24), 
 found both these substances in addition to the other bodies mentioned by 
 Scherer. 
 
 f Various analyses of menstrual blood and of the lochial discharge are re- 
 corded in my translation of Simon's "Animal Chemistry," vol. i. pp. 337 339. 
 
 J Compt. rend. vol. xxxi. p. 630. 
 
 R 2 
 
244 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Blood in 
 different 
 
 diseases. 
 
 Inflam- 
 matory 
 diseases. 
 
 poor in hmatocrystallin, and increase the water and colour- 
 less corpuscles to a considerable extent, while the fibrin is 
 apparently unaffected.* 
 
 (221.) We shall confine our remarks on the condition of 
 the blood in different diseases to those cases in which well- 
 marked peculiarities of composition are manifested. 
 
 In inflammatory diseases, especially when they are accom- 
 panied by general febrile excitement, we always have a greater 
 or lesser augmentation of the fibrin, the increase varying with 
 the degree and duration of the inflammation; the fibrin 
 reaches its maximum f in pneumonia and acute articular rheu- 
 matism. At the same time there is usually, but not in- 
 
 * The following table, quoted in p. 249. of the first volume of my translation 
 of Simon's " Animal Chemistry," fully bears out the statement made in the 
 text: 
 
 Mean Composition of the Blood of Ten Persons bled Three Times. 
 
 1st Venesection. 2d Venesection. 3d Venesection. 
 
 Density of defibrinated blood 
 Water .... 
 
 - 1056-0 
 793-0 
 
 1053-0 
 
 807-7 
 
 1049-6 
 833-1 
 
 Solid constituents 
 
 207-0 
 
 192-3 
 
 176-9 
 
 Fibrin - 
 
 3-5 
 
 3-8 
 
 3-4 
 
 Blood-corpuscles - 
 Albumen - 
 
 129-2 
 - ' 65-0 
 
 116-3 
 63-7 
 
 99-2 
 64-6 
 
 Extractive matters and salts 
 TTflt 
 
 7-7 
 
 6-9 
 
 l-Kft 
 
 8-0 
 
 f The highest amount of fibrin ever observed by Andral and Gavarret, in 
 their numerous analyses of morbid blood, was 10-5^, and the largest quantity 
 ever found by Simon was 9-15-^; Rindskopf and Scherer found this con- 
 stituent amount to 12726$} (Simon's "Animal Chemistry," vol. i. pp. 262,265). 
 In all these cases the disease was pneumohia. In acute rheumatism Andral and 
 Gavarret once found 10'2 in the blood. The following table shows the mean 
 amount of fibrin in the blood in various inflammatory diseases, as determined 
 by Becquerel and Rodier. (See their "Traite de Chimie Pathologique," Paris, 
 1854, p. 105.) 
 
 The normal quantity of fibrin in health being . . . . 25 
 
 Its quantity in acute bronchitis is 4-8 
 
 in acute pleurisy .6*1 
 
 m acute pneumonia j firstbleedin S - I* 
 ( second bleeding . . .68 
 
 in acute articular rheumatism '.*.. 5*8 
 
THE BLOOD. 245 
 
 variably, a slight diminution of the blood-cells.* The 
 albumen of the serum is. diminished f, especially when 
 there is much exudation. The salts are slightly dimi- 
 nished, and the fats (especially the cholesterin) somewhat 
 increased. 
 
 Is there any connexion between the augmentation of the 
 fibrin and the diminution of the corpuscles ? Simon believed 
 that the fibrin is the result of a special transformation of the 
 corpuscles ; and the circulation being accelerated in inflam- 
 matory diseases, the globules are exposed more frequently 
 than in the normal state to the action of the oxygen in the 
 lungs, and that an excessive production of fibrin in a given 
 time was the result. The most powerful argument against 
 this view is that no such augmentation of the fibrin occurs 
 when we have accelerated circulation without inflammation, 
 as in fever. 
 
 Another and more probable theory is that the augmenta- 
 tion of fibrin is due to an excessive transformation of albumen 
 into fibrin a view which is supported by the fact that the 
 augmentation of the former corresponds pretty nearly, in a 
 numerical point of view, with the diminution of the latter 
 (see the Table in last page). 
 
 Andral and Gravarret, and subsequently Becquerel and Eo- Fevers. 
 dier, have made numerous analyses of the blood in typhoid 
 and typhus fevers, as well as in simple continuous fever ; it 
 does not, however, appear that the blood in these cases pre- 
 
 * Becquerel and Rodier, who fix the normal quantity of blood-cells at 132 % 
 their physiological limits heing 145 and 125, find that in the inflammatory 
 diseases mentioned in the preceding note the mean quantity of corpuscles was 
 123-3. 
 
 f The normal quantity of albumen in 1000 parts of normal serum being, 
 according to these observers, 80, they found that the mean quantity in twenty 
 cases of inflammatory disease (first bleeding) was 73-35 ; and in ten cases of 
 second bleeding, 64-84. 
 
 R 3 
 
246 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 sents any very well marked constant deviations from the 
 normal type. 
 
 In cholera the blood has a very high specific gravity *, and 
 is remarkably tough and viscid : the corpuscles are increased 
 in number, but are abnormally poor in salts ; the amount of 
 fibrin is unaffected ; the serum is very dense, being extremely 
 rich in albumen and containing more potash-salts and phos- 
 phates (though less salts collectively) than normal serum ; it 
 moreover usually contains some urea, together with an ex- 
 tractive matter, which seems to act as a ferment and to 
 convert the urea very rapidly into carbonate of ammonia. 
 
 In dysentery the number of corpuscles is diminished ; the 
 fibrin is sometimes, but not always, increased ; the solid con- 
 stituents of the serum, and especially the albumen, are 
 diminished, while the salts are increased. 
 
 In Bright's disease the blood is impoverished, both in rela- 
 tion to the corpuscles and to the solid constituents of the 
 serum ; the cholesterin and the salts of the serum are however 
 increased. Urea, either in mere traces or in very appreciable 
 quantity, may be almost always recognised in the solid 
 residue of the serum, and we sometimes can detect carbonate 
 of ammonia as a product of its decomposition. 
 
 In the condition known as plethora, the corpuscles are 
 always somewhat augmented ; the fibrin is unaffected, and 
 the albumen of the serum is slightly above the average. 
 
 In true anaemia (by which we understand a deficiency in 
 the quantity of circulating fluid) the blood exhibits no pecu- 
 liarities of composition. The term anaemia is, however, often 
 incorrectly used to signify hydrsemia, which is a frequent con- 
 comitant of dropsy. The blood here occurs as a very 
 
 * The blood in cholera has been carefully examined by Schmidt (Charak- 
 teristik d. Epidem. Cholera, 1850). While in healthy men the specific gravity 
 is T0599, the mean specific gravity in male patients with cholera was 1-0701; 
 and, similarly, in female patients it was 1-062, the healthy specific gravity being 
 1-0503. 
 
THE BLOOD. 247 
 
 attenuated, pale, watery fluid, and in coagulating it forms a 
 loose, infiltrated, gelatinous clot. Its composition is the 
 same as in Bright's disease, except that there is usually no 
 excess of urea. 
 
 In chlorosis the blood forms a small firm clot, floating on Chlorosis. 
 a large quantity of clear serum, and often covered with a 
 buflfy coat. The corpuscles, and consequently the iron, are 
 always diminished, often to an extraordinary degree. Bec- 
 querel and Kodier found that while the mean normal amount 
 of corpuscles in woman's blood was 127-Q-Q, the mean amount 
 in chlorosis was 86*83, and they once found the number as 
 low as 45-38). The composition of the plasma is usually 
 normal. 
 
 In typhus (the abdominal form), during the first week, Typhus. 
 the composition of the blood closely resembles the condition 
 of that fluid in plethora, and there is likewise a slight aug- 
 mentation of the fibrin ; but from about the ninth day the 
 corpuscles and the solid residue of the serum begin to 
 diminish, and continue to do so with a rapidity proportional 
 to the intensity of the intestinal affection. 
 
 The blood in puerperal fever has been carefully examined Puerperal 
 by several chemists, whose results are somewhat discordant. 
 There is a considerable diminution of the corpuscles, and 
 corresponding augmentation of fibrin (especially if there is 
 much peritonitis), but it is soft and gelatinous; and there 
 is almost always a buffy coat. In most cases, but not in- 
 variably, the collective solid constituents of the serum are 
 much diminished, while the extractive matters are con- 
 siderably increased. Bile-pigment and free lactic acid have 
 been found in the serum. 
 
 We know nothing of the state of the blood in pyaemia, Pysemia. 
 except that the fibrin is diminished and that there is a great 
 augmentation of the colourless corpuscles. 
 
 The blood in leucaemia an affection which is usually Leucaemia, 
 accompanied by a considerable enlargement of the spleen - 
 
 R 4 
 
248 PHYSIOLOGICAL CHEMISTRY. 
 
 presents in many respects a close resemblance to the blood of 
 the splenic vein. Scherer * has made two examinations of 
 leucaemic blood, in each case obtained from the body after 
 death ; and the results are so remarkable that we shall give 
 them somewhat fully. 
 
 In neither case did the blood spontaneously coagulate in a 
 thorough manner : it merely formed a gelatinous semi-coagu- 
 lated thick mass, whose surface was at first blackish, but, on 
 exposure to the air, soon became more or less red, thus giving 
 to the whole mass a black and red marbled appearance. In 
 the first case the blood had a faintly acid reaction, perfectly 
 coagulated when boiled with water, and the filtrate was found 
 to contain many remarkable substances that do not commonly 
 occur in the blood, namely *<*; 
 
 (1.) Grlutin, or a substance closely allied to it. 
 
 (2.) A peculiar organic matter, forming an intermediate 
 link between the albuminous bodies and glutin. 
 
 (3.) Hypoxanthine to the amount of 8 or 10 grains in 
 4 ounces of blood. (The substance was previously discovered 
 by Scherer in the spleen, and traces of it have been found in 
 the normal blood of oxen. (See page 50.) 
 
 (4.) Formic, acetic, and lactic acids. 
 
 In the second case the blood did not coagulate so perfectly 
 on boiling, and the filtrate did not exhibit the slightest ten- 
 dency to gelatinise ; hence the glutin found in the first case 
 was here absent. The following substances, pertaining to the 
 splenic juice, were however detected in the filtrate : hypoxan- 
 thine, leucine (which was not looked for in the first case), and 
 uric, lactic, and formic acids. 
 
 The character from which leucsemic blood derives its name 
 is due to the great excess of colourless corpuscles. 
 
 Carcinoma. The condition of the blood in carcinoma has been examined 
 by several chemists (amongst whom we may mention Grorup- 
 
 * Verhandl. d. phys.-med. Gesellsch. zu Wiirzburg, 1852, vol. ii. pp. 
 321325: and 1856, vol. vii. pp. 123126. 
 
THE BLOOD. 249 
 
 Besanez *) who concur in the opinion that there is a great 
 excess of fibrin even when no febrile symptoms are present. 
 Lehmann seems to doubt whether this substance, which is 
 found in such excess, actually is true fibrin. There is also a 
 slight diminution of the corpuscles. 
 
 In diabetes the blood, except that it contains an excess of Diabetes, 
 sugar, scarcely differs from the normal type. 
 
 (222.) Numerous analyses of the blood of various animals Blood of 
 (mammals, birds, reptiles, and fishes) have been made by ^dTof 
 Andral, Gavarret, and Delafond, by Dumas and Prevost, by animals. 
 Simon, and by Nasse, and the results obtained by these che- 
 mists are recorded at considerable length in my translation of 
 Simon's " Animal Chemistry." f 
 
 Amongst mammals we find that the blood of omnivorous 
 animals (as the pig) contains more corpuscles (and conse-. 
 quently more iron and phosphates), more fibrin, and more 
 collective solid residue of the serum, but less salts, than the 
 blood of other animals. The blood of carnivorous animals 
 presents nearly as many corpuscles as that of omnivorous 
 animals, but as compared with herbivorous animals it con- 
 tains less fibrin and more fat. 
 
 The blood of birds is as rich in corpuscles as that of omni- 
 vorous animals, and contains more fibrin and fat, but less 
 albumen than that of most mammals. 
 
 In all the cold-blooded animals (reptiles and fishes) the 
 blood is poorer in corpuscles and richer in water than in 
 mammals or birds. . 
 
 Notices of the blood of various molluscs and of insects may 
 be found in Lehmann's e( Physiological Chemistry." f 
 
 (223.) The quantity of blood in the living body can only Quantity 
 
 of blood 
 in the 
 
 * Arch. f. Physiol. Heilk. vol. viii. pp. 523525. body, 
 
 f Vol. i. pp. 339 350. Tbe reader who wishes for further information on 
 the blood of the domestic animals may be referred to Colin's Traite de Phy- 
 siologic Comparee des Animaux Domestiques, Paris, 1856, vol. ii. pp. 174 
 184, which, however, contains no original investigations, 
 j Vol. ii. pp. 256 258, 
 
250 PHYSIOLOGICAL CHEMISTRY. 
 
 be determined approximately. Physiologists have varied in 
 their estimates, according to the manner in which they tried 
 to determine the point, from 8-5 to 44 pounds. In the pre- 
 sent day the blood is generally estimated at about 22 pounds, 
 which is equal to about the eighth part of the weight of the 
 whole body. From experiments on two decapitated crimi- 
 nals (young men) Lehmann believes that this number is too 
 high, and estimates the quantity at about 18 or 19 pounds. 
 The fane- (224.) We pass, without notice, the numerous recent in- 
 vestigations regarding the origin and seat of formation of the 
 
 disintegra- blood-corpuscles (both colourless and red) because this is a 
 
 tion of the V 
 
 blood-cells, subject pertaining almost exclusively to histology.* Various 
 functions have been assigned to the blood-cells. Liebig and 
 Mulder, although holding very different views as to the mode 
 in which the process was effected, concurred in the idea that 
 the red corpuscles were conveyers of oxygen to the tissues, 
 and the removers of carbonic acid from them, the oxygen 
 being taken up by them in the lungs when they gave off 
 their carbonic acid. Although Henle and other physiologists 
 have brought forward various observations which seem op- 
 posed to this theory, it is so strongly supported by the fact 
 that neither the intercellular fluid nor the serum alone has 
 the power of absorbing more than a very small quantity of 
 oxygen, while the cell-containing blood exhibits a great capa- 
 city for absorption, that we may regard the view which 
 ascribes to the corpuscles the function of absorbing oxygen 
 and giving it partially off in the capillaries as completely 
 established. The second part of the theory, viz. that they 
 carry carbonic acid from the tissues to the lungs, is however 
 not so firmly established, for the intercellular fluid exhibits a 
 considerable capacity for dissolving carbonic acid, and hence 
 
 * The subject is fully discussed in Lehmann's Physiological Chemistry, 
 vol. ii. pp.270 274; Kolliker's Manual of Human Histology, translated by 
 Busk and Huxley, vol. ii. pp. 342 347 ; and Funke's Wagner's Physiologic, 
 p. 132, where the functions of the blood-cells are also very ably considered. 
 
THE BLOOD. 251 
 
 the co-operation of the blood-corpuscles would not be re- 
 quired. 
 
 After what has been already stated regarding the action of 
 oxygen on the colour of the blood (see p. 212) and on the 
 hgematocrystallin (see p. 95), the question becomes almost 
 unnecessary, whether the oxygen is only mechanically taken 
 up by the corpuscles, or whether it enters into chemical com- 
 bination with some of the constituents of the corpuscles, and 
 thus directly gives rise to the formation of carbonic acid in 
 the capillaries. Both these modes undoubtedly occur. It is 
 clearly proved by numerous experiments that the greater part 
 of the oxygen absorbed in the lungs is only mechanically 
 taken up, or is conveyed to the capillaries in a very unstable 
 form of combination. And direct observations show us that 
 the corpuscles are acted upon chemically by oxygen : the 
 difference in the chemical constitution of arterial and venous 
 corpuscles can scarcely be explained except by the assumption 
 of a chemical action of the oxygen upon the corpuscles or 
 some of their constituents in the lungs. Lehmann found the 
 mineral substances and the hsematin augmented in the cor- 
 puscles after the inspiration of oxygen, whilst the organic 
 substances, and especially the fats, are either destroyed by 
 oxidation and their products of decomposition transferred to 
 the intercellular fluid, or at all events they undergo a con- 
 siderable diminution of weight by the formation of water and 
 carbonic acid. 
 
 The blood-corpuscles must be regarded as cells having spe- 
 cial contents, and their activity of metamorphosis must vary 
 with the nature of the fluid in which they are suspended (the 
 plasma). The actual metamorphoses that result from the 
 reciprocal action of the cells and the plasma are not however 
 yet accurately known. " As far as we are at present able to 
 form an opinion on this subject, we think we shall not be 
 deviating very widely from the truth if we regard the blood- 
 cells as organs, that is to say, as laboratories, in which the 
 
252 PHYSIOLOGICAL CHEMISTRY. 
 
 individual constituents of the plasma are prepared for the 
 higher function of aiding in the formation and reproduction 
 of the tissues." * 
 
 The blood-corpuscles, like all other vital cells, doubtless 
 have a definite period of existence, although we do not know 
 what that period is, and the mode and process of their disin- 
 tegration are equally unknown to us. We know this much, 
 however, that the cells of the same blood vary in the length 
 of time during which they can resist destructive chemical 
 agents, and hence it is conjectured that the cells which first 
 give way are the old ones. We may presume, from a com- 
 parison of the blood taken in repeated venesections, that the 
 life of the red corpuscles is not very short, for the great defi- 
 ciency of these bodies in the blood for a comparatively long 
 period after repeated or copious venesections proves that their 
 regeneration is not very rapid. 
 
 The question whether the blood-corpuscles are generally 
 disintegrated throughout the whole circulating system or at 
 one definite spot, is still undecided. The liver was formerly 
 regarded (by Schultz and F. C. Schmid) as the special seat of 
 this destructive process, but recent comparative analyses (by 
 Lehmann) of portal and hepatic venous blood show that, on 
 the contrary, the liver should rather be regarded as an organ 
 for the regeneration of these cells. The view, supported on 
 histological grounds by Kolliker and Ecker, that the spleen is 
 the principal seat of disintegration of the blood-corpuscles, is 
 strongly confirmed by the investigations of Scherer, to which 
 we have referred in p. 243. He found in the splenic juice 
 various transition stages of the products of decomposition 
 of the albuminous bodies and of the blood-pigment itself, 
 and it seems almost definitely established from his re- 
 searches, that the spleen aids in the destruction of those 
 corpuscles which are no longer fit for the due performance of 
 their functions. 
 
 * Lehmann's Physiological Chemistry, vol. ii. p. 278. 
 
THE CHYLE. 253 
 
 SECTION II. THE CHYLE. 
 
 (225.) The chyle differs very considerably in its physical The chyle 
 characters, according as it is obtained from an animal during ^ P^y 8 
 digestion or while fasting, and according to the part of the 
 chyliferous system from which it is procured ; moreover, the 
 nature of the food very considerably modifies the character of 
 the chyle. For chemical examination it is most conveniently 
 obtained from the thoracic duct, at or near the point where it 
 opens into the subclavian vein. During digestion, especially 
 if fat has been present in the food, it presents an almost 
 milk-white appearance ; while in animals that have not re- 
 cently taken food, it is only opalescent, and varies from a 
 yellowish white to a pale red colour : it has a faint animal 
 odour, a saline and somewhat mawkish taste, and a very slight 
 alkaline reaction. Like the blood, it coagulates in nine or ten 
 minutes after its removal from the body ; the coagulum, which 
 usually continues to contract for about three hours, is rela- 
 tively much smaller than that of the blood, and is very soft and 
 friable, being often a mere jelly. It is usually of a pale yellow 
 tint, but becomes of a pale red colour on exposure to the air. 
 The serum of the chyle always remains somewhat turbid, and 
 it is rendered clearer by ether, which takes up the fat, and 
 generally becomes more opaque on the addition of acetic acid. 
 On boiling it we seldom have a decided, curdy coagulation ; 
 but it generally assumes a milk-white appearance from sus- 
 pended molecules of coagulated albumen. 
 
 (226.) True or typical chyle, that namely which accumu- Its mor- 
 lates during the latter stages of digestion, is very rich in elements, 
 morphotic elements ; being an extremely plastic fluid, it pre- 
 sents almost every phase of cell-development. We find an 
 abundance of fine molecular granules, spherical aggrega- 
 tions of these granules, cytoid corpuscles, with a simple or 
 divided nucleus (chyle-corpuscles), and fat-globules (see 
 
254 PHYSIOLOGICAL CHEMISTRY. 
 
 Plate V.fig. 6). It is doubtful whether there is any essen- 
 tial perceptible difference between these chyle-corpuscles, 
 the lymph-corpuscles, and the colourless blood-cells. 
 Its che- (227.) The chemical constituents of the chyle are fibrin, 
 
 stitucnts 11 " acumen, fat, salts, and the so-called extractive matters. 
 
 The fibrin of the chyle appears to be less perfectly elabo- 
 rated than that of the blood : it is far less contractile, often 
 remaining in a gelatinous form, and frequently redissolving 
 after its coagulation; under the microscope it does not 
 exhibit the fibrous texture of firmly-coagulated blood-fibrin, 
 and dissolves much more readily than the latter in saline 
 solutions. Its quantity has not been determined in human 
 chyle, but is far less than occurs in the blood. 
 
 The albumen is combined wih more alkali than in the 
 blood : hence, on boiling the chyle-serum, we do not observe 
 a coagulation in flakes or clots, but the fluid becomes opaque 
 and milky, and a similar effect is produced on the addition of 
 acetic acid. On evaporation it forms a colourless membrane 
 on the surface. The quantity of albumen in the chyle-serum 
 is much smaller than in the serum of the blood. 
 
 The presence of casein in the serum of the chyle has been 
 maintained by some chemists, but cannot be regarded as 
 established. 
 
 There is usually a considerable quantity of fat in the chyle, 
 some of it being saponified and some existing as free fat. Its 
 amount is very variable, being chiefly dependent on the 
 nature of the food. 
 
 With regard to sugar, Lehmann observes that it can only 
 be found in the chyle after the use of amylaceous food, and 
 then only in traces ; while Bernard maintains that sugar is 
 present, but that it is conveyed into the chyle by the hepatic 
 absorbents. 
 
 The solid residue of the chyle yields about 12-- of mineral 
 constituents, of which more than three-fourths are soluble 
 salts. Alkalies abound in this fluid, being partly combined 
 
THE CHYLE. 255 
 
 with albumen, the fatty acids, and lactic acid, and partly 
 with phosphoric acid and chlorine. Of 9'4g of soluble salts, 
 which were yielded by the solid residue of the chyle of a cat, 
 7'1 parts were chloride of sodium. It is a disputed question 
 whether or not there is any iron in the serum of the chyle, 
 but the probability is that, as in the case of the blood, it 
 can only be regarded as a normal constituent of the cor- 
 puscles. 
 
 (228.) With regard to the influence of the food on the influence 
 composition of the chyle, it may be regarded as established, c ' od< 
 that when an animal is being starved, or kept on insufficient 
 diet, this fluid becomes poorer in solid constituents, and 
 especially in fat, so that it appears merely turbid, and loses its 
 milky colour. This milkiness is due solely to the fat taken 
 in the food, and has no special connection with a purely 
 animal, or purely vegetable diet. 
 
 The changes which the chyle undergoes in its course from 
 the intestinal villi to the thoracic duct, are more amenable to 
 microscopical than to chemical investigation. It is in its 
 passage through the mesenteric glands that fibrin first ap- 
 pears in the chyle; and the albumen and solid constituents 
 generally, with the exception of the free fat, are augmented 
 after it reaches the receptaculum chyli ; the fat being partly 
 saponified, and partly entering into the formation of the 
 chyle-corpuscles. 
 
 Nothing definite is known regarding the morbid conditions 
 of the chyle. 
 
 (229.) Various attempts have been made to determine the Quantity 
 quantity of chyle poured into the blood ; some physiologists * 
 having endeavoured to collect it by opening the thoracic duct 
 in the neck of a living, or just killed animal, and others f, 
 having formed estimates by a comparison between the albu- 
 
 * Cruickshank, Magendie, also Bidder (in Miiller's Arch. 1845. p. 46). 
 f Vierordt (in Arch. f. Phys. Heilk. vol. vii. p. 281), and Lehmann 
 (Phys. Chem, vol. ii. p. 291). 
 
256 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 minates or fats that are absorbed, and the quantities of 
 those substances found in the chyle. It would appear from 
 the latest investigations on this subject, that the quantity of 
 chyle poured into the subclavian vein in twenty-four hours, is 
 probably about the same as the whole mass of the blood, that 
 is to say, about one-fifth of the weight of the body. 
 
 SECTION III. THE LYMPH. 
 
 (230.) The lymph is a colourless, or faintly yellowish-red, 
 slightly opalescent fluid, of a rather saltish taste, and with an 
 alkaline reaction. It coagulates in from four to twenty 
 minutes after its removal from the lymphatic system, and 
 then forms a jelly-like, colourless, or pale red coagulum, 
 which continues for some time to contract, so that at last 
 the clot is very small in proportion to the serum. 
 
 The lymph that has been submitted to chemical analysis 
 has usually been such as has spontaneously flowed from wounds. 
 It is a matter of great difficulty to find and lay open the 
 lymphatics in the higher animals, and to obtain their contents 
 free from blood and other admixtures. 
 
 (231.) Besides fat globules and nucleus-like formations, 
 we observe on microscopic examination, large numbers of 
 cytoid corpuscles (the lymph-corpuscles), which do not essen- 
 tially differ from the colourless blood-cells, or from mucus- or 
 pus-corpuscles. Blood-corpuscles have only been found in 
 the lymphatics of the spleen, and in the lymph of starving 
 animals. 
 
 (232.) The chemical constituents of the lymph seem to 
 be precisely those of the blood, if we except the substances 
 peculiar to the red corpuscles ; as may be seen by the following 
 analysis made by Scherer*, of fluid obtained from the sac- 
 
 * Verhandl. d. phys.-med. Gesellschaft zu Wiirzburg, vol. vii. p. 268. This 
 is probably the most correct analysis of the lymph that has yet been made. 
 
THE LYMPH. 257 
 
 cular, distended lymphatics of the spermatic cord of a man. 
 The quantity obtained weighed 13*456 grammes, or about 
 215 grains. The clot weighed 1-005 grammes, or 0-3 71-^. 
 In 1000 parts of lymph he found 
 
 Water ...... 957-60 
 
 Solid constituents .... 42-40 
 
 Fibrin and lymph-corpuscles . 0*37 
 
 Albumen and extractive matter . 34-72 
 
 Inorganic matters . . . 7*31 
 
 The ash contained a somewhat large amount of chlorine, 
 phosphoric acid, and sulphuric acid, a good deal of potash, 
 some soda, small quantities of earthy phosphates and iron, 
 and no carbonic acid. 
 
 From the older analyses referred to in the note, Lehmann 
 infers that the quantity of fibrin in the lymph, as compared 
 with that in the blood-plasma, is very small ; that the quan- 
 tity of albumen is relatively smaller, and that of salts rela- 
 tively larger ; that the lymph contains far less solid consti- 
 tuents than the blood-plasma; that the fat occurs in small 
 quantities, and for the most part in a saponified form ; that 
 the extractive matters occur in larger quantity in the lymph 
 than in the blood-serum ; and that salts of ammonia and 
 pre-formed sulphates, are found in considerable quantities. 
 
 (233.) From Bidder's experiments on animals, he infers Its quan- 
 that thirteen kilogrammes, or upwards of 28lbs. of fluid, pass tlty * 
 through the thoracic duct of an adult man into the subclavian 
 vein in the course of twenty-four hours. If his view be cor- 
 rect, that not more than about three kilogrammes of true 
 chyle (the product of digested food) are formed daily, the 
 remaining ten kilogrammes, or 22lbs., must represent the 
 quantity of true lymph formed in twenty-four hours.* 
 
 Other analyses by Gmelin, Marchand and Colberg, L'Heretier, Dr. Eees, 
 Lassaigne, and Nasse are given in my translation of Simon's " Animal Che- 
 mistry," vol. i. pp. 351 353. 
 
 * See, however, the statement, regarding the daily quantity of chyle, in last 
 page. 
 
 S 
 
258 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Transuda- 
 tions dis- 
 tinguished 
 from secre- 
 tions and 
 exudations. 
 
 Conditions 
 on which 
 transuda- 
 tion is de- 
 pendent 
 
 SECTION IY. TRANSUDATIONS. 
 
 (234.) Under the term, transudations, Lehmann, and 
 other recent writers on Physiological Chemistry, include 
 those fluids which consist of liquid constituents of the inter- 
 cellular portion (or plasma) of the blood which have transuded 
 in an unchanged state through the capillaries. They are dis- 
 tinguished from secretions, in the strict sense of the word, by 
 their containing neither any peculiar element, nor any ac- 
 cumulation of matters that exist only sparingly in the blood ; 
 and from exudations, on various grounds, which will be 
 noticed when we speak of the latter class of fluids, and of 
 which it is sufficient to mention one in the present place, 
 namely, that the latter are due to morbid action, while the 
 former depend on purely physical laws. Hence, we include 
 among the transudations, the normal secretions of the various 
 serous membranes,, the tears, the aqueous humour of the eye, 
 the liquor amnii, and the parenchymatous fluid which moistens 
 and nourishes the tissues. 
 
 (235.) The escape of the water and of the other consti- 
 tuents of the plasma through the walls of the capillaries, is 
 solely dependent on physical conditions ; namely, on the pe- 
 netrability of the walls of the capillaries, on the rapidity of 
 the motion of the blood within them, and on the physical 
 and chemical characters of the circulating fluid. As these 
 conditions vary, so will the transudation be more or less mo- 
 dified in its physical or chemical characters. But all trans- 
 udations (whether normal or excessive) have in general much 
 the same properties as the intercellular fluid itself; they are 
 colourless, transparent, of a faintly saline taste, and of an 
 alkaline reaction ; and their specific gravity is usually some- 
 what lower than that of the intercellular fluid, or of the 
 serum of the blood. 
 
TRANSLATIONS. 259 
 
 (236.) The morphotic elements which they contain are Morphotic 
 dependent on the surfaces on which they are effused ; and elements - 
 hence we may meet with epithelial structures, molecular 
 granules, cytoid corpuscles, &c. Red corpuscles can only 
 occur when there has been laceration of the capillaries, and 
 their presence indicates that we are not dealing with a pure 
 transudation. 
 
 (237.) Transudations are never thoroughly identical in Chemical 
 their chemical composition with the intercellular fluid of the c 
 blood ; for the different constituents permeate the walls of the 
 capillaries with different degress of facility ; and as water per- 
 meates most readily, it necessarily follows that transudations 
 must contain a larger amount of this constituent than the 
 plasma. Again, since the soluble salts and the extractive 
 matters permeate animal membranes more readily than al- 
 bumen, and since albumen permeates them more freely than 
 fibrin, we find that the transudations, as contrasted with the 
 plasma, contain a relative excess of salts and extractive 
 matters, and a relative deficiency of albumen ; while fibrin is 
 either present in extremely small quantities, or is altogether 
 absent. 
 
 (238.) No fibrin is usually found in normal transudations Fibrin, 
 from serous membranes, or in those effusions which occur with- 
 out an inflammatory condition of the capillaries ; hence it is 
 absent in those cases of accumulation of fluid, which arise from a 
 disturbance of the function of the lymphatics, or from an excess 
 of water in the blood. If, however, the blood-current be much 
 impeded, or if it be perfectly stopped in the capillaries, fibrin 
 always escapes through the attenuated walls of the vessels. 
 Some capillaries may, in their normal state, allow the trans- 
 mission of fibrin, a view that is supported by the occurrence 
 of fibrin in the lymph, and by its constant presence in the 
 ordinary plastic exudations ; as for instance, in the non- 
 sanguineous secretion of fresh incised wounds. 
 
 Fibrin may often be contained in transudations, when from 
 
 S 2 
 
260 PHYSIOLOGICAL CHEMISTRY. 
 
 its small quantity, and from its having already undergone 
 some change, it may escape detection. Even assuming 
 (which is not the case) that fibrin passed into transudations 
 with the same facility as albumen, and recollecting that in 
 the plasma the fibrin does not amount to more than one- 
 twentieth of the albumen (4-05 : 78-84, see pp. 205207,) it 
 is obvious that transudations could never contain more than 
 very minute quantities of fibrin ; and if we further consider 
 that the fibrin in the parenchymatous juices is very rapidly 
 applied to the reparation of tissues, and in morbid transuda- 
 tions to the formation of false membranes, &c., we need not 
 wonder that it is so often absent. 
 
 No fibrin can be detected in those normal transudations 
 which occur in the animal body f -as, for instance, in the mois- 
 ture of serous sacs, the aqueous humour of the eye, the 
 tears, the liquor amnii, certain dropsical effusions, in cutaneous 
 vesicles or bullse (whether artificially excited or consequent on 
 a skin disease), or in secretions from the intestinal capillaries, 
 as in the diarrhoea arising from intestinal catarrh or drastic 
 purgatives, or accompanying cholera,* 
 
 In those inflammatory conditions in which fibrin is found 
 in the transudations, its quantity may be very variable, but 
 will always be less (in the case of recent effusions) than that 
 existing in the corresponding plasma. The fibrin in these 
 fluids usually forms a loose gelatinous coagulum, but in all 
 other respects seem to be identical with blood-fibrin. 
 Albumen. (239.) The albumen occurring in transudations in no way 
 differs, either chemically or physically, from the albumen of 
 the blood. It frequently happens, however, that the whole, 
 or part of the albumen in transudations assumes a casein-like 
 
 * In opposition to the statement contained in the text, it should, however, be 
 observed that Tilanus (De Saliva et Muco, Amstelodami, 1849, p. 72) found 
 true coagula in the fluid contained in a blister caused by boiling water; and that 
 Picard (De la Presence de 1'Uree dans le Sang, Strasbourg, 1856, p. 34) saw 
 the contents of an ordinary blister coagulate like frog's blood from which the 
 cells had been removed. 
 
TRANSLATIONS. 261 
 
 character; that is to say, it does not coagulate on heating, 
 is precipitated by dilute acetic acid, and separates in the form 
 of a superficial membrane on evaporation ; these are, as we have 
 seen in p. 106, the characters of albuminate of soda, which is 
 more abundant in these transudations than in the blood. 
 
 The quantity of albumen in different transudations is very 
 variable. It is scarcely to be detected in the tears, in the 
 aqueous humour of the eye, in the liquor amnii (in the 
 latter stages of pregnancy), in the fluid of the lateral ven- 
 tricles and of the spinal canal, and in the fluid of the connec- 
 tive tissue in oedema of the extremities ; while in the fluid of 
 hydrocele Lehmann found as much as 6'283, and in a peri- 
 toneal effusion Hoppe found 7'73-g- of albumen. This varia- 
 tion is, however, by no means arbitrary, but is dependent on 
 certain propositions or conditions, for the knowledge of which 
 we are chiefly indebted to C. Schmidt. 
 
 The following are the most important of these proposi- 
 tions : 
 
 a. The quantity of albumen seems to be dependent on the 
 system of capillaries through which the transudation has 
 been effused. 
 
 Schmidt arrived at his knowledge of this proposition by a 
 series of carefully conducted parallel analyses of normal and 
 abnormal transudations. He found the transudation in the 
 pleura to be richest in albumen (2'85-g-), that in the perito- 
 neum considerably poorer (l'13--), that within the cranial 
 membranes yet more deficient in this substance (0-6 to 0-8 -), 
 and that in the subcutaneous connective tissue the poorest 
 (0*36^-). He found the albumen in these proportions in the 
 transudations of the same person, who died with Bright's dis- 
 ease; and he convinced himself, by further investigations 
 regarding the normal transudation of the cerebral capillaries 
 and hydrocephalic effusions, that not only does the relative 
 quantity of albumen always remain tolerably equal when 
 there is an excess of the transudation, but also when, after 
 
 s 3 
 
262 PHYSIOLOGICAL CHEMISTRY. 
 
 the removal of the old effusion, a new transudation occurs 
 through the same capillaries. 
 
 His observations in support of this proposition are, con- 
 firmed by corresponding analyses by Lehmann and other 
 chemists*; but, like most natural laws, this law is so modified 
 in its results by other laws, that its direct recognition is not 
 very obvious. It is not true that under all and the most 
 varied conditions the quantity of albumen in the transuda- 
 tion yielded by the same group of capillaries is always in 
 precisely the same ratio. The proposition is only true to 
 this extent, that when, under equal conditions, there are 
 several excessive transudations effused from various serous 
 membranes, we have one and the same proportion between 
 the quantities of albumen in the transudations of the dif- 
 ferent sets of capillaries. Although the transudation is 
 doubtless very much influenced by the thickness or the 
 delicacy of the capillaries, its composition, and consequently 
 its amount of albumen, will vary with other conditions which 
 we shall now proceed to notice. 
 
 fi. Another proposition deducible from the analyses of 
 Schmidt, Lehmann, &c., is, that the amount of albumen in 
 the transudation is proportional to the slowness with which 
 the blood permeates the capillaries. Thus, for instance, in 
 transudations into the peritoneal cavity, we find more albu- 
 men when they are caused by the pressure of large tumours 
 on the abdominal veins, than when produced by lesser me- 
 chanical obstructions, such, for instance, as incipient cirrho- 
 sis; and similarly, the albumen is more abundant in the 
 effusion in acute than in chronic hydrocephalus. 
 
 7. Finally, the amount of albumen in a transudation is 
 always dependent on the quantity of albumen in the blood. 
 Thus, for instance, in Bright's disease, where the kidneys are 
 
 * A detailed account of these analyses is given in Lehmann's Physiological 
 Chemistry (English edition), vol. ii. pp. 316 318; and in Lehmann and Hup- 
 pert's Zoochemie, 1858, pp. 236-238. 
 
TRANSUDATIONS. 263 
 
 continuously removing albumen from the blood, the transu- 
 dations are very poor in albumen ; and all dropsical effusions 
 which originate in disturbances in the circulating system, are 
 richer in albumen than those which depend upon too watery 
 a state of the blood. 
 
 (240.) The other constituents of transudations require a 
 comparatively brief notice. 
 
 True casein has never been found in these fluids. Casein. 
 
 The extractive matters always occur in larger quantities in Extractive 
 the transudations than in the serum of the corresponding 
 blood ; and they are more abundant in the older stagnating 
 fluids than in those that have been more recently separated, 
 and in serous than in nbrinous transudations ; thus, whilst in 
 the serum of normal blood the albumen is to the extractive 
 matters as 100 to 5, it is as 100 to 8, or even to 16, in fresh 
 nbrinous transudations ; and in fresh serous transudations it 
 is as 100 to 12, or even to 30 ; and in older ones as 100 to 
 42, or even to 86. Hence, it might be inferred that these 
 substances transude through the capillaries in larger quan- 
 tities than the albumen ; and this is proved to be the case by 
 the analyses of normal transudations ; as, for instance, the 
 fluid within the pericardium, the cerebral and spinal fluids, 
 the liquor amnii, the tears, and the aqueous humour, in 
 which the ratio rises to 100 : 300 ; indeed, the quantity of 
 albumen may be so diminished as to be scarcely quantitatively 
 determinable. The amount of extractive matters seems gene- 
 rally to vary with the composition of the blood, and with the 
 group of capillaries through which the fluid has been effused. 
 It must further be recollected that in the transition of albu- 
 men into textural elements, which occurs during the or- 
 ganisation of a transudation, a portion of the albumen yields 
 extractive matters, which thus in part accounts for the abso- 
 lute and relative augmentation of the last-named substances. 
 
 o 
 
 We find a smaller proportion of saponifiable and saponi- 
 fied fats in transudations than in the corresponding plasma 
 
 s 4 
 
264 PHYSIOLOGICAL CHEMISTRY. 
 
 % 
 
 of the blood ; but in these cases also the capillaries seem to 
 exert a certain influence, for the fluids exuded by the capilla- 
 ries of the arachnoid membrane, the pericardium, and the 
 subcutaneous connective tissue, are especially poor in fatty 
 matters. 
 
 Cholesterin usually occurs in larger quantities in these 
 fluids than the fats and fatty salts ; indeed, in some cases (in 
 the fluid in ovarian dropsy and in hydrocele) it occurs in 
 such quantity that these transudations present the appear- 
 ance of opaque fluids, or even of semi-fluid masses.* 
 
 Bile-pigment has not only been observed in the transuda- 
 tions in cases of jaundice, but also in normal transudations. 
 Lehmann found it in considerable quantity in two cases of 
 hydrocele. 
 
 Sugar. Sugar has been found in the serous fluids in diabetes, 
 
 even in the serum obtained from the application of a blister. 
 It is generally believed that no sugar occurs in the pleuritic, 
 peritoneal, and pericardial transudations of non-diabetic pa- 
 tients ; but Grohe f found sugar in the transudations in a 
 case of chronic pleurisy and in a case of epilepsy ; and Fre- 
 richs found it in the fluid of ascites in the case of a girl, aged 
 nine years, suffering from fatty liver. Lehmann, on the 
 other hand, sought in vain for it in more than three pints of 
 a peritoneal transudation obtained from a drunkard with 
 granular liver. Bernard maintains that the peritoneal trans- 
 udations of rabbits and horses, especially when they have 
 been fasting for some time, contain sugar, which takes its 
 origin from the lymphatics of the liver. Sugar, or at all 
 events a substance which reduces oxide of copper (Trommer's 
 test), occurs in the cerebro-spinal fluid and in the liquor 
 amnii. 
 
 * In a hydrocele-fluid, which formed a tolerably consistent pulp, Lehmann 
 found 3-0412 o f pure cholesterin, amounting to 38'2g of the solid residue. This 
 substance likewise occurs abundantly in the fluid of the choroid plexus, and in 
 transudations into the peritoneum and pleura. * 
 
 f Verhandl. d. phys.-med. Gesellschaft zu Wiirzburg, vol. iv. p. 2. 
 
TRANSUDATIONS. 265 
 
 We have already (see p. 46) noticed the presence of urea 
 in the fluids of the eye * and in the liquor amnii. It has 
 been found by Schmidt in the fluid of chronic hydrocephalus ; 
 by Grohe and others in pleuritic and pericardial effusions, 
 even when there was no apparent disease of the kidneys ; by 
 Picard, in the fluid obtained from the application of a blister 
 in a case of ascites ; by F. Miiller, in the fluid of hydrocele ; 
 by Eedenbacher f , in the peritoneal effusion in cirrhosis of 
 the liver ; and by Wolff, in the fluid of ranula. In Bright's 
 disease it occurs in all the fluid effusions. 
 
 Since urea is often found in considerable quantity in the 
 transudations, we might naturally expect to find some of the 
 other products of regressive metamorphosis, such as uric and 
 hippuric acids, creatine, creatinine, &c. Hitherto, however, 
 none of these substances have been detected, excepting crea- 
 tinine, which Scherer thinks that he has found in the liquor 
 amnii. 
 
 In some of those cases of puerperal fever in which the Organic 
 blood assumes an acid reaction, Scherer has found lactic acid acids ' 
 
 * In the fluids of the eyes of a woman, who died from puerperal peritonitis 
 and pleuritis, Picard found 0*5g of urea. 
 
 f Kedenbacher in an inaugural dissertation, Ueber die Zusammensetzung 
 hydropischer Transudate bei Lebercirrhose, 1858, gives two analyses of such 
 transudations, both of which contained urea. The composition of these fluids 
 which were obtained by paracentesis was as follows : 
 
 In 1000 parts there were contained 
 
 (1.) (2.) 
 
 Water ------- 947'1 713 986-666 
 
 Albumen 42-0500 8-490 
 
 Urea 1-1214 0-776 
 
 Chloride of sodium 2-5233 0-874 
 
 Fatty and extractive matters - - - 3-0240 1-461 
 
 Fixed salts - ... - - 4-1100 1733 
 
 Sulphuric and phosphoric acids - - traces traces. 
 
 The whole quantity of the discharged fluid in the first analysis weighed 
 12,380 grammes, or between 24 and 25 Ibs.; its specific gravity was 1-018, and 
 it contained 13'9 grammes, or about 214 grains of urea; while the fluid which 
 yielded the second analysis amounted to 18,900 grammes, or 37 Ibs., had a 
 specific gravity of T008, and contained 14-7 grammes, or 226 grains, of urea. 
 
266 PHYSIOLOGICAL CHEMISTRY. 
 
 in the transudations, in one case as much as O105 of the 
 free hydrated acid. Lehmann believes (although he has not 
 definitely proved) that lactates frequently occur in transuda- 
 tions. Succinic acid has been found (see p. 16) in the fluid 
 contents of hepatic cysts containing echinococci, and in the 
 fluid of hydrocele; and acetic acid was once discovered by 
 Simon in the fluid of pemphigus. Generally, however, the 
 fluids in pemphigus, herpes, and eczema, are alkaline, and 
 contain albumen. 
 
 The soluble salts transude in a comparatively greater ratio 
 than the organic substances, and always occur in the effused 
 fluids in nearly the same proportion as in the corresponding 
 blood-serum. In dropsy complicated with Bright's disease, 
 we frequently, however, have an exception to this rule, for 
 the salts in the transudations then often exceed those of the 
 blood-serum. 
 
 No salts of ammonia can be detected in normal and 
 recent transudations. 
 
 Like all the animal fluids, the transudations contain gases ; 
 of these carbonic acid is most abundant, but oxygen and 
 nitrogen also admit of being determined with certainty. 
 
267 
 
 CHAPTER XII. 
 
 THE FLUIDS CONNECTED WITH GENERATION AND 
 DEVELOPMENT. 
 
 SECTION I. THE SEMINAL FLUID. 
 
 (241.) The seminal fluid, as it occurs after ejaculation, is Its general 
 mixed with the secretion of the prostate and other smaller c aracter> 
 glands. In this state it is a viscid, opalescent, colourless 
 substance (which however becomes yellowish on drying) with 
 a peculiar odour ; it is considerably heavier than water, and 
 neutral or faintly alkaline ; when freshly discharged it is 
 somewhat gelatinous, but after standing for some time it 
 becomes thoroughly fluid, and, if mixed with water, forms a 
 mucous sediment ; it is coagulated by the action of alcohol, 
 but not by that of heat. 
 
 In order to procure the seminal fluid in a state of purity 
 we must obtain it from the vasa deferentia or the vesiculce 
 seminales of animals in the rutting season ; but in this way 
 we cannot obtain it sufficiently copious for chemical analysis. 
 It has sometimes been obtained for chemical examination 
 (in the case of fishes) by incising and pressing the testicles. 
 
 The characteristic morphotic elements of the semen are the Its mor- 
 seminal filaments or spermatozoa. As their form and mea- mentis, 
 surements are given in all recent works on physiology, it is 
 not necessary for us here to do more than mention what little 
 is known of their chemical constitution, and of the effect of 
 various chemical reactions on them. It appears from the 
 researches of Frerichs that the spermatozoa obtained from the 
 
268 PHYSIOLOGICAL CHEMISTRY. 
 
 carp (and the semen of fishes, birds, and mammals possesses, 
 according to him, essentially the same chemical composition) 
 " consist of binoxide of protein, the same substance which 
 Mulder has proved to be the principal constituent of the 
 epithelia, as well as of the horny tissues in general, and 
 contain about 4g of a butter-like fat, as well as phosphorus 
 in an unoxidised state and about 5-g- of phosphate of lime." * 
 
 Kolliker has recently studied the effects of various reagents 
 on the vitality of fche spermatozoa. The following are some 
 of the most important of his results. (1.) Water, and watery 
 solutions of innocuous neutral substances and salts, suspend 
 the motions of the spermatozoa. (2.) In the solutions of 
 many indifferent organic substances of moderate concentration 
 (of the various kinds of sugar, Of albumen, urea, glycerin, 
 salicin, and amygdalin) the spermatozoa seem unaffected. 
 (3.) Some solutions of indifferent organic substances, even in 
 a state of concentration, act like water, as for instance gum 
 arabic, vegetable mucilage, and dextrine. (4.) Many organic 
 substances suspend the motions of the spermatozoa by exerting 
 a chemical action on them, as for instance, alcohol, creosote, 
 tannin, and ether, while other substances, as most of the oils 
 mechanically produce the same effect. (5.) Metallic salts, 
 even when extraordinarily diluted (as for instance one 
 part of corrosive sublimate in 10,000 parts of water), destroy 
 their motions. (6.) Solutions of most of the alkaline and 
 earthy salts exert a deleterious influence, destroying them 
 in from 1 to 4 hours. (7.) Acids, even when very diluted (as 
 for instance one part of hydrochloric acid in 7500 of water), 
 soon prove fatal. 
 
 Our knowledge of the chemical composition of the seminal 
 fluid is not satisfactory. Vauquelin found in ejaculated 
 human semen 6-- of organic matter, to which he applied the 
 name of spermatin ; Kolliker found in the seminal fluid of a 
 
 * Cyclopaedia of Anatomy and Physiology. Art. Semen, vol. iv. p. 506. 
 
THE FLUIDS OF THE EGG. 269 
 
 bull 15-265% and in that of a horse 16-449. The fatty 
 matter in the bull's semen amounted to 2-165^-. The same 
 salts occur in the semen as are found in the blood, phosphate 
 of lime and especially phosphate of magnesia preponderating. 
 In the fluid filtered portion of the seminal fluid of the carp 
 Frerichs found an excess of chloride of sodium together with 
 alkaline phosphates and sulphates. 
 
 SECTION II. THE FLUIDS OF THE EGG. 
 
 (242.) The egg in its fresh state consists mainly of the yelk, The yelk ; 
 
 which in the case of birds is surrounded by a tolerably thick ticdements 
 
 layer of white, or albumen, and is invested by a calcareous and chemi- 
 
 i XT, i, 11 cal corn- 
 envelope, the shell. position. 
 
 We know little regarding the chemistry of the yelk except 
 in the case of birds and fishes.* It occurs as a viscid, thick, 
 yellowish red, or purely yellow inodorous fluid, with a slight 
 but a peculiar taste; mixed with water it forms a white 
 emulsion; it has a slightly alkaline reaction, solidifies on 
 boiling, coagulates in cold alcohol, and when shaken with 
 ether yields to that fluid a reddish or amber-coloured fat, 
 while a tough white mass is precipitated. 
 
 On examining the yelk under the microscope we find 
 that it consists of yelk-corpuscles and fat-globules of various 
 sizes interspersed between immeasurably minute granules. 
 The fat-globules are distinguished by a less intense yellow 
 colour, and by being covered with a layer of fine granules, 
 while the yelk -corpuscles are invested with a capsule which is 
 usually dotted with granules. 
 
 * It is true that Valenciennes and Fremy (Journal de Chim. et de Pharm. 
 3 ser. 1854, vol. xxvi. pp. 516, 321 326, and 415 423 ; and Sillimann's 
 Journal, 1855, vol. xix. pp. 3848, 238 243, and vol. xx. pp. 6572) have 
 examined the yelk in birds, fishes, amphibia, Crustacea, insects, and mollusca ; 
 but they describe so many new, and probably doubtful, proximate principles 
 (ichthin, ichthulin, ichthidin, and emydin), that I have not deemed it expedient 
 to introduce their investigations into the text. 
 
270 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 The yelk-corpuscles consist chiefly of fat containing phos- 
 phorus (probably glycero-phosphoric acid) and of the yelk- 
 pigment; and the capsules amount to about 0-5 g- of the 
 yelk. 
 
 The molecular granules interspersed through the yelk 
 consist of casein which dissolves readily in alkaline salts ; 
 this casein forms about 14g- of the yelk. 
 
 Albumen is likewise a constituent of the yelk ; it occurs in 
 a dissolved form and amounts to about 3-g-. The substance 
 formerly known as vitellin and described as a constituent of 
 the yelk, is merely an admixture of casein and albumen (see 
 p. 114). 
 
 The fats occurring in the yelk have not yet been thoroughly 
 examined. They consist, however^ principally of margarin and 
 olein in association with a substance which, in its high point 
 of fusion and its crystalline form (rhombic tablets), closely 
 resembles cholesterin, with which however it is not perfectly 
 identical. Lecithin and cerebrin (two substances discovered by 
 Gobley in the substance of the brain and which will be 
 noticed in the section " On the Brain and Nervous Tissue ") are 
 said also to occur in the yelk-fat. The latter probably gives 
 origin to the glycero-phosphoric acid which has been detected 
 in the yelk. The collective fats amount to about 3Og- of the 
 yelk-fluid. 
 
 Lehmann invariably found grape-sugar in the yelk. 
 
 The pigments have not been thoroughly examined. We 
 know little more than that there is both a yellow and a red 
 pigment and that at least one of them contains iron. 
 Potassium In examining the mineral constituents of the yelk we find a 
 and phos- 3 g reati preponderance of the potassium-compounds and the 
 phates. phosphates ; chlorine and sodium being present in extremely 
 minute quantities. The ash contains from 67 to 70-g- of 
 phosphoric acid, and consequently the phosphates must be 
 monobasic. The total amount of mineral constituents averages 
 15% of the yelk. 
 
THE FLUIDS OP THE EGG. 271 
 
 The water in the yelk varies considerably, ranging from 48 Water in 
 to 55. yelk ' 
 
 The egg of the common hen contains on an average 15*2 
 grammes (234 grains) of yelk and 23*9- grammes (368 grains) 
 of white. 
 
 The most important constituent of the white is albumen, The white 
 which is for the most part in combination with soda; it 
 amounts to about 12*5-- of the whole white. 
 
 Margarin occurring in heaps of acicular crystals may be 
 detected by the microscope in the white, which also contains 
 olein, and oleate and margarate of soda. 
 
 Grape-sugar occurs in the whites both of fresh and of Sugar, 
 incubated eggs, and averages 5-g- of the dried residue. 
 
 The mineral constituents of the white consist chiefly of Salts, 
 soluble salts the reverse of what occurs in the yelk. The 
 ash contains about 50-g of chlorides, while the phosphates and 
 potassium-compounds occur in comparatively small quantity. 
 Some of the soda is combined with carbonic acid. A little 
 silica occurs both in the white and in the yelk, and fluorine 
 has been detected in the former. The fresh white contains 
 on an average O66^ of mineral constituents. 
 
 The water contained in the white ranges from 82 to 88-g-. Water. 
 
 The shell of the egg, both in birds and amphibia, consists 
 almost entirely of carbonate of lime (about 97-g-), with a 
 little phosphate of lime, traces of magnesia, and a very little 
 organic matter. 
 
 The variety of colour on the eggs of different birds seems to 
 be due to certain modifications of the bile-pigment with which 
 the egg comes in contact in the cloaca. (Wicke.) 
 
 We know little or nothing regarding the chemical changes 
 which the egg undergoes during incubation. 
 
 (243.) After nine days' incubation, the amnotic fluid is found The am- 
 to be of a pale yellow colour, and to contain little albumen ; aiiantoic 1 
 after fourteen days' incubation, it contains so much albumen fluids of the 
 
 *^ Ci)lCK 
 
 that it solidifies on heating. Its reaction is alkaline. 
 
272 PHYSIOLOGICAL CHEMISTRY. 
 
 The allantoic fluid is, at the commencement of incubation, 
 very limpid, and contains no albumen ; after fourteen days 
 incubation it has become turbid, from the separation of uric 
 acid ; and after seventeen days, it is found to have become 
 opaque, of a yellowish -white colour, and faintly acid in its 
 reaction. It deposits uric acid freely, and is said to contain 
 urea. 
 
 For the following facts regarding the mammalian ovum, we 
 are mainly indebted to the researches of Schlossberger * and 
 Majewski.f 
 
 The liquor amnii in the embryo of the sheep and the pig 
 is always clear and colourless ; in that of the cow it is clear 
 and colourless at a very early period, but subsequently be- 
 comes yellow, viscid, and turbid ; it is always alkaline in its 
 reaction. It is always poor in solid constituents, which, 
 however, increase during the process of foetal development 
 from 0-55 to 1*9. Albumen is always present, in propor- 
 tions ranging from 0*1 to 0'2-g-, but diminishes, and some- 
 times quite disappears towards the end of foetal life (at all 
 events in the human subject), and is replaced by a mucin-like 
 substance, which occurs in considerable quantity. Neither 
 true casein nor fibrin exists in it. Sugar is found in con- 
 siderable quantity (from 0-06 to 0*19^ in the sheep, and from 
 0-1 to O3 in the cow) in the liquor amnii of herbivorous 
 animals ; it occurs in mere traces in this fluid in the pig, and 
 is altogether absent in man. (This observation is in complete 
 accordance with Bernard's J recent discovery of special glyco- 
 genic cells in the placenta in some animals (rodents) and in 
 the amnion of others.) Urea is always present and increases 
 with the age of the foetus, its maximum quantity being about 
 0*4 g. The mineral substances consist chiefly of phosphates 
 
 * Ann. d. Ch. u. Pharm.vol. xcvi. pp. 6775, and vol. ciii. pp. 193199. 
 f De Substantia, &c. Diss. Inaug. Dorpat, 1858. I have not had an op- 
 portunity of seeing this thesis. The results are quoted by Lehmann. 
 f Compt. Rend. vol. xlviii. pp. 7786. 
 
THE MILK. 273 
 
 and of chloride of sodium, and, like the urea, increase with 
 the age of the foetus ; they range from 0-14 to 0-75-g-. In the 
 liquor amnii of the cow the mineral are to the organic matters 
 in about the ratio of 1 to 1*5. 
 
 The allantoic fluid more closely resembles the amniotic in 
 its chemical characters than we should have expected from 
 their different physiological relations. At an early stage it is 
 colourless, but subsequently becomes yellow or reddish. Its 
 reaction is always alkaline. Its solid constituents increase 
 with the development of the foetus from 0-65 to 3-83^. It 
 contains no albumen, but urea and sugar are two or three 
 times as abundant in it as in the amniotic fluid. The amount 
 in which its characteristic ingredient, allantoine (see p. 49) 
 occurs in it, has never been definitely determined. The 
 mineral substances are more abundant than in the corre- 
 sponding liquor amnii, amounting towards the end of preg- 
 nancy to 0-876-g- in the sheep, and i-073 in the cow. 
 
 (244.) The (so-called) uterine milk of the ruminants (the 
 secretion of certain glands lying in the interior of the uterus of 
 these animals) has been examined by Schlossberger. It consists 
 of a cream-like fluid, containing neither casein, fibrin, nor 
 sugar. It has a weak acid reaction, and was found to contain 
 9-5-g- of albumen (including cellular structures and extractive 
 matter), 1-5-g- of fat, and O7 of mineral matters, consisting 
 of acid phosphate of alkali and lime, and a little chloride of 
 sodium and iron. 
 
 SECTION III. THE MILK. 
 
 (245.) The milk is an opaque white fluid, with frequently its phy- 
 a bluish-white or yellowish tinge; it is devoid of odour slcal P r< 
 (except for a short time after its extraction), is of a slightly 
 sweet taste, most commonly of an alkaline reaction, and its 
 specific gravity varies from 1-018 to 1-045, the average in 
 women being 1-032. 
 
 T 
 
274 PHYSIOLOGICAL CHEMISTRY. 
 
 When milk has been allowed to stand for some time, a 
 thick, fatty, yellowish-white stratum (the cream) forms upon 
 its surface, while the fluid below has become poorer in 
 fat, of greater specific gravity, and of a more bluish-white 
 colour. Milk does not coagulate on boiling, but a membrane 
 or film of coagulated casein, containing fat-corpuscles, forms 
 upon its surface. If milk be allowed to stand for some time, 
 exposed to air of the ordinary temperature, it gradually begins 
 to exhibit an acid reaction (from the formation of lactic acid 
 from the milk-sugar), and the casein becoming coagulated, 
 the fluid gradually assumes the form of a thickish pulp. 
 Eennet (the dried mucous membrane of the fourth stomach 
 of the calf) rapidly induces coagulation, whether the milk be 
 acid or alkaline. 
 
 Itsreac- Human milk almost invariably presents an alkaline re- 
 
 action *, that of the carnivora is acidf, while that of the 
 herbivora is generally but not invariably alkaline. In stall- 
 feed animals (cows, mares, and ewes) kept on green food it is 
 however frequently acid.J 
 
 Its mor- When examined under the microscope the milk appears as 
 
 elements. a c l ear &viid containing fat-globules (the milk-globules) in 
 suspension (see PL F. fig. 7, a). They commonly vary from 
 0012 to '0018'" in diameter, although a few may usually be 
 seen both above and below these measurements. When 
 simply observed under the microscope, they do not present 
 any evidence of an investing membrane. The existence of 
 such a membrane may however be demonstrated in either of 
 the following ways. First, if we add dilute acetic acid to 
 
 * Elsasser (at Schlossberger's suggestion), examined the reaction of the 
 milk in 385 women, most of whom were healthy. In forty -five instances it 
 was neutral, and in all the rest alkaline, and even in these forty-five cases the 
 milk was found on other occasions to he alkaline. Kattenmann obtained a 
 very similar result from an examination of 272 cases. 
 
 f Proved by the researches of Bensch (Ann. d. Ch. u. Pharm. voL Ixi. 
 pp. 222227), liu'ff (ibid. vol. Ixxxvii. pp. 317324), and others. 
 
 J Ruff (Op. cit.) and others. 
 
THE MILK. 275 
 
 milk under the microscope, the globules exhibit changes of 
 form which they could not possibly experience if they were 
 mere fat-globules, for they become much distorted and 
 wrinkled, and from most of them small fat-globules are seen 
 to escape. Secondly, if milk be shaken with ether it does not 
 lose its emulsive appearance ; but if a little caustic potash be 
 first added, which dissolves the investing membrane, the 
 milk, if it is then shaken with ether (which takes up all the 
 fat) becomes transparent and almost limpid. 
 
 The colostrum-corpuscles which occur in the milk for the 
 first three or four days after delivery, and which often present 
 themselves at a later stage if any disease supervenes, are 
 irregular conglomerations of very small fat-globules, which are 
 held together by an amorphous granular matter of an 
 albuminous nature. See PL V. Jig. 7, b. 
 
 Epithelial cells, mucous corpuscles, coagula of fibrin, 
 blood-corpuscles, and some of the very lowest forms of vege- 
 tation are occasionally found in morbid states, but are not 
 entitled to rank among the normal microscopic constituents 
 of milk. 
 
 (246.) The chemical constituents of the milk are casein, Chemical 
 
 consti- 
 fatty matter, sugar, and salts. tuents. 
 
 The amount of casein in human milk has been variously Casein, 
 estimated, the differences being probably in a great measure 
 due to the different modes of analysis. The most trustworthy 
 of these estimates are given in the foot-note.* In healthy 
 human milk it seems to range from 2*7 to 3'5-g-, while in the 
 colostrum (according to Simon) it amounts to 4. In the 
 milk of the ass it is less than 2-g-, in that of the cow it 
 
 * Clemm determined the quantity of casein at 3-37g, Simon (taking the mean 
 of a large number of cases) at3*5, and Haidlen at3-lg, in good milk, and at 
 2-7 in an inferior specimen. Vernois and Becquerel, taking the average of 
 eighty-nine cases, found the casein and extractive matters (which they did not 
 separate from each other), to amount to 3'924, the extremes being l-932 and 
 7'092g. 
 
 T 2 
 
276 PHYSIOLOGICAL CHEMISTRY. 
 
 ranges from 3 to 4^, and in that of the bitch from 8-3 to 
 
 The quantity of casein increases with the free use of animal 
 food, and diminishes on a vegetable diet. 
 
 During the first two months after delivery there is an 
 excess of casein ; from the tenth to the twenty-fourth month 
 there is a diminution. (Vernois and Becquerel.) 
 
 Fatty The fatty matters have hitherto been only examined in 
 
 cows' milk. They collectively form an almost colourless or 
 slightly yellow mass, which after being fused solidifies at 
 about 80 F. ; and consists of 68-g- of margarin *, 3O- of olein, 
 and 2-g- of an admixture of fats, which on saponification yield 
 butyric, caproic, caprylic, and capric acids (or sometimes 
 vaccinic acid instead of butyric and caproic acids). 
 
 In woman's milk the fatty matters varyf from 2-5 to 4-3-g-, 
 in cows' milk they average 4-5-g-, in mares' milk 6-95^-, in 
 asses' milk 1*25^-, in ewes' and goats' milk 4-g-, and in bitches' 
 milk 11. Human colostrum contains 5, that of the cow 
 2'6-g- and that of the ass 5g- of fatty matters. 
 
 According to Simon, the quantity of fat contained in 
 woman's milk remains nearly the same throughout the whole 
 period of lactation. 
 
 The experiments of Boussingault and others show that in 
 the case of the cow the nature of the food in some degree 
 influences the amount of fat contained in the milk; and 
 Dumas found that the milk of bitches was somewhat richer in 
 fat when they had been fed on vegetable than when they 
 had been fed on animal food. 
 
 * The investigations of Heintz tend to show that the solid fat, which we have 
 here designated as margarin, consists of four different neutral fats, which on 
 saponification yield four solid fatty acids, differing from each other by C 4 H 4 , 
 namely, myristic acid C 28 H 28 4 , palmitic acid C 32 H 32 O 4 , stearic acid, C 36 H 36 O 4 , 
 and butic acid C 40 H 40 O 4 . (See p. 6.) 
 
 f Simon found from 2-53 to 3'88 ; Clemm found 4-3g on the fourth day, 
 3'53 on the ninth day, and 3-35g on the twelfth day ; while Vernois and 
 Becquerel found an average of 2'67g, the extremes being 0-666 and 5'642. 
 
THE MILK. 277 
 
 It has been proved by Peligot and Eeiset that the milk 
 which is last yielded is much richer in fat than that which is 
 first drawn, although the composition of both portions is 
 otherwise the same. This is true not merely in the cow and 
 the ass, but in respect to woman's milk. 
 
 Milk-sugar or lactine varies in human milk from 3-2 to 
 6-2^-, and in cows' milk from 3'4 to 4-3^; in asses' milk it 
 averages 4-5-g-, in mares' milk 8'7--, in that of sheep and goats 
 4'3-g- ; the milk of bitches when fed on a purely animal diet 
 often contains mere traces of sugar. 
 
 Human colostrum contains about 7$ of sugar ; the milk six 
 days after delivery contains 6'24-g-, and the quantity of sugar 
 subsequently diminishes. (Simon.) 
 
 The nature of the food exerts a certain influence on the 
 amount of sugar. When fed upon a purely animal diet 
 bitches yield milk containing little or no sugar, but if they 
 are fed on vegetable food their milk contains a considerable 
 quantity of that constituent. (Bensch and Poggiale.) 
 
 In the human subject no essential influence seems to be 
 exerted upon the quantity of sugar either by deficient or 
 superabundant food. (Simon, Vernois and Becquerel.) 
 
 Milk which is secreted freely and abundantly contains more . 
 sugar than milk secreted sparingly. (Vernois and Becquerel.) 
 
 The salts consist of the chlorides of potassium and Salts, 
 sodium and of the alkaline and earthy phosphates, together 
 with potash and soda in combination with the casein of the 
 milk. No sulphates or salts of ammonia are found in fresh 
 milk. A little peroxide of iron occurs in the ash, which 
 likewise contains traces of fluorine. (Wilson.) 
 
 The milk of women contains from O16 to O25$ of salts*, 
 cows' milk from 0-55 to 0*85^, and the milk of bitches from 
 1-2 to 1-5-g-. The amount of the soluble salts is in general 
 
 * Vernois and Becquerel place the salts as low as 0-138^, the'extremes being 
 055 and 0'338g. 
 
 T 3 
 
278 
 
 PHYSIOLOGICAL CHEMISTKY. 
 
 Gases. 
 Lactic acid. 
 
 Abnormal 
 consti- 
 tuents. 
 
 Albumen. 
 
 smaller than that of the insoluble phosphates, in the ratio of 
 1 to 2 or 3. 
 
 The extractive matters occurring in the milk have not yet 
 been carefully examined, and little is known regarding either 
 their quantity or their composition. 
 
 Free gases, and especially carbonic acid, can always be shown 
 to be present in fresh milk. 
 
 Lactic acid is not contained in the fresh healthy milk either 
 of women or of herbivorous animals. In the occasional cases 
 in which cows' milk has been found acid (see p. 274), it has 
 not been determined whether the acidity was due to lactic 
 acid, to butyric acid, or to the presence of acid phosphates. 
 The milk of the bitch (and probably of all carnivora) is 
 neutral when the animal is kept on vegetable food, while it is 
 always acid when the food has been exclusively animal ; in 
 this case the acid reaction is most probably due to super- 
 phosphate of lime. 
 
 (247.) Abnormal constituents have seldom been detected 
 in the milk, although daily experience shows us that certain 
 kinds or modifications of milk exert a deleterious effect on 
 the infant. 
 
 Albumen, according to Lehmann, is only to be found in the 
 milk in inflammatory affections of the mammary glands, 
 unless, indeed, we regard the coagulable ingredient of the 
 colostrum to be albumen, which is not the case. Other che- 
 mists, however (amongst whom we must place Quevenne, 
 Mitscherlich, Doyere, Grirardin, Morin, and Bouchardat), 
 maintain that albumen, or a substance closely allied to it, exists 
 as a normal constituent of milk ; and Lieberkiihn admits that 
 milk, in addition to casein, contains a nitrogenous substance 
 coagulable by heat, which, however, is not (in his opinion) 
 pure albumen, although allied to it. Some protein-substance 
 differing from ordinary casein certainly occurs occasionally in 
 some kinds of apparently healthy milk; for Scherer has 
 obtained a casein from normal milk which coagulated by 
 
THE MILK. 279 
 
 heat; and both Dumas and Bensch found that the milk of 
 the bitch became pulpy, and was even almost coagulated on 
 being heated, when the animal had. been kept on vegetable 
 food, as well as when it was fed on animal matters, while on 
 cooling it very frequently again became thinly fluid. 
 
 Fibrin and ha3matin may be detected if blood is present. Fibrin. 
 
 Urea has been found in the milk in cases of Bright's Urea, 
 disease. 
 
 (248.) Much has been written regarding the passage of Passage of 
 foreign substances, such as pigments, medicines, and poisons, iJJj^the 
 into the milk. That iodide of potassium enters the milk is milk - 
 unquestionable ; Personne has obtained a deposit of mercury 
 on a gold plate from the milk of a woman who had been 
 taking small doses of protiodide of mercury for a fortnight ; 
 and Landerer has detected quinine in the milk of a wet-nurse : 
 other chemists have however been less successful. 
 
 Grape-sugar and cane-sugar do not pass in their unchanged 
 state into the milk; they are converted in the mammary 
 glands into milk-sugar. 
 
 (249.) We shall now briefly notice certain physiological 
 conditions of the milk, beginning with the colostrum. 
 
 The colostrum generally appears as a turbid yellowish fluid, The colos- 
 resembling soap and water, having a viscid consistence and a 
 strongly alkaline reaction. It passes more readily into lactic 
 fermentation than ordinary milk, and exhibits an excess of 
 solid constituents both in women and animals, the augmenta- 
 tion being most marked in cows, asses, and goats, in the 
 casein, and in women in the sugar. The colostrum is richer 
 in fat than the corresponding milk, and contains from two to 
 three times more salts. 
 
 (250.) The following physiological influences have been Various 
 carefully studied by Vernois and Becquerel : logica! in . 
 
 1. The influence of the age of the nurse. 
 
 2. The influence of the age of the milk. 
 
 3. The influence of the presence of colostrum. 
 
 T 4 
 
280 PHYSIOLOGICAL CHEMISTRY. 
 
 4. The influence of the constitution of the nurse. 
 
 5. The influence of the number of children. 
 
 6. The influence of pregnancy. 
 
 7. The influence of the development of the breast. 
 
 8. The influence of the retention of the milk in the 
 breasts. 
 
 9. The influence of menstruation. 
 
 10. The influence of the colour of the hair. 
 
 11. The influence of the food. 
 
 12. The connexion between the state of the health of the 
 infant and the milk. 
 
 13. The influence of the quantity of the milk. 
 
 In order to afford data for comparison, we must give Ver- 
 nois and Becquerel's table of the composition of healthy 
 human milk. This table represents the mean of eighty-nine 
 analyses. 
 
 Specific gravity . . . * 1032-67 
 
 Water . . . . . 889-08 
 
 Solid constituents . . . 110-92 
 
 Sugar . . . . . 43-64 
 
 Casein and extractive matters . 39-24 
 
 Butter .; . ^' / V . 26-66 
 
 Salts yielded by incineration * . 1*38 
 
 1. The age of the nurse does not exert any marked influ- 
 ence on the specific gravity, the proportion of water, or that of 
 solids, unless when we contrast extremes, when we find that the 
 milk of nurses aged from fifteen to twenty years contains much 
 more solids than that of nurses aged from thirty to forty years. 
 
 The period at which the milk most nearly approximates to 
 
 The relative proportions of the individual salts were as follows : 
 
 Salts insoluble in water 0775, namely V carbonate of lime, 0-069. 
 
 J I phosphate of lime, 0-706. 
 
 0*225 C chloride of sodium, 0-098. 
 
 Soluble salts, . ^ sulphate of soda, 074. 
 
 (other salts, 0-053. 
 
 See, however, the more minute analysis in the note to p. 285. 
 
THE MILK. 281 
 
 the physiologically normal type is for the ages of twenty to 
 thirty years. 
 
 2 and 3. During the first fortnight the specific gravity of the 
 milk is slightly diminished ; there is a constant diminution in 
 the quantity of water (resulting from an excess of butter), a 
 diminution of sugar, and an augmentation of casein, butter, 
 and salts. 
 
 The colostral state especially augments the quantity of 
 butter. 
 
 The composition of the milk from the first to the twenty- 
 fourth month presents the following varieties : 
 
 There is no law regarding the variations of density. 
 
 The greatest quantity of water (901-51) occurs from the 
 fifth to the sixth month ; the least (872-92) during the first 
 two months. 
 
 The sugar is in excess from the eighth to the tenth month 
 (reaching 47*62), and is deficient during the first month 
 (40-40). 
 
 The casein is in excess during the first two months (48-26), 
 and is most deficient between the tenth and eleventh months 
 (31-06). 
 
 The butter is in excess during the first three months, espe- 
 cially the first month, when it reaches 39-55. 
 
 The salts are most abundant during the first month, but 
 present no regular law of decrease. 
 
 4. The composition of the milk in nurses of a weak consti- 
 tution appears to be normal, while in nurses of very vigorous 
 frame the weight of the solid portion is diminished. 
 
 5. The milk of a nurse with a first child more nearly 
 resembles the physiological type than that of women who have 
 borne many children. 
 
 6. Pregnancy in its later stages augments the amount of 
 the solid constituents of the milk. 
 
 7. The state of development of the breasts does not exer- 
 cise any marked influence on the milk. 
 
282 PHYSIOLOGICAL CHEMISTRY. 
 
 8. The time during which the milk is retained in the breast 
 does not seem in the case of women to exert any influence on 
 the fluid, whereas in the cow and the ass the last-drawn por- 
 tion yields very considerably more butter than the first-drawn 
 milk. (See however, p. 277.) 
 
 9. The influence exerted by menstruation presents ques- 
 tions regarding which there have been great differences of 
 opinion. Vernois and Becquerel only met with ten cases in 
 which menstruation occurred during lactation, and in only 
 three of them could they procure the milk both before and 
 during menstruation. 
 
 The composition of the milk during menstruation appears 
 to be modified as follows : The density is diminished, the 
 quantity of water sensibly diminished, the sugar slightly 
 diminished, the casein somewhat augmented (once to 42*19), 
 the butter much augmented in one case (to 67*74) and much 
 diminished in another (to 10*67), and the salts slightly 
 increased. 
 
 10. The milk of women with dark hair exceeds in quality 
 that of women with light hair, approaching more nearly to 
 the normal type in reference to each of its constituents. 
 
 11. The averages yielded by the milk of well-fed nurses 
 closely approximate to the normal type. A deficient supply 
 of food causes an augmentation of the water, due chiefly to 
 the diminution of the casein and butter. 
 
 12. Where the state of health of the infant is satisfac- 
 tory, the milk never deviates much from the normal type ; 
 when on the other hand the infant does not thrive, we usually 
 find a low specific gravity and a considerable augmentation 
 of the butter (rising as high as 33*22 in place of 26*66). 
 
 13. An excessive secretion of milk has no effect upon the 
 specific gravity. The water, butter, and salts, are slightly 
 diminished, and the sugar and casein somewhat increased. 
 When the secretion of milk is scanty, the water and butter 
 are in excess, while the sugar and the casein are diminished. 
 
THE MILK. 283 
 
 (251.) Vernois and Becquerel enter at great length into the Milk in 
 consideration of the milk in various diseases. The following 
 is a brief summary of their principal results. 
 
 In acute febrile diseases, such as enteritis, colitis, pleurisy, 
 metro-vaginitis, and metro-peritonitis, the milk presents the 
 following average composition ; 
 
 Density 1031-20 
 
 Water 884-91 
 
 Solid constituents . *.! ' . , : . 115'09 
 
 Sugar . . . . ;';*- : 'V 33-10 
 
 Casein and extractive matters . 50-40 
 
 Butter 29-86 
 
 Salts ... . . . 1-73 
 
 Comparing this with the table in p. 280 representing the com- 
 position of healthy milk, we see that there is an augmentation 
 of the solids collectively, and of the butter, the casein, and 
 the salts individually, with a corresponding diminution of the 
 sugar. 
 
 In typhoid fever, all the solid constituents of the milk 
 occur in diminished quantities, excepting the casein which 
 seems unaffected. The butter is especially diminished. 
 
 In chronic diseases without fever, the only peculiarities 
 usually are a slight augmentation of the casein and a great 
 increase of butter. 
 
 In pulmonary phthisis with diarrhoea and emaciation, the 
 solids are considerably diminished, mainly owing to the great 
 decrease of butter, which falls on an average to 12*76, and 
 was once observed as low as 6-9. 
 
 In syphilis it appears from an examination of the milk in 
 nine cases that the density is increased (in one case to 
 1037-5), the butter is diminished (on an average to 15-87, 
 once to 9-12), and the salts are considerably increased. 
 Antisyphilitic treatment by mercurials increases the quan- 
 tity of butter. 
 
284 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 The milk (252.) The following table represents the composition of 
 of animals. iQOO p ar t s of milk in various animals, as deduced from the 
 analyses of Vernois and Becquerel. 
 
 Daily 
 quan 
 milk. 
 
 
 Density. 
 
 Water. 
 
 Solid Con- 
 stituents. 
 
 Casein and Ex- 
 tractive Matters. 
 
 Sugar. 
 
 Butter. 
 
 Salts.' 
 
 Woman - 
 
 1032-67 
 
 88908 
 
 110-92 
 
 39-24 
 
 43-64 
 
 26-66 
 
 1-38 1 
 
 The Cow - - r 
 
 1033-38 
 
 864-06 
 
 135-94 
 
 55-19 
 
 38-03 
 
 36-12 
 
 6-64 
 
 The Ass - " -' 
 
 1034-57 
 
 890 12 
 
 109-88 
 
 35-65 
 
 50-46 
 
 18-53 
 
 5-24 
 
 The Mare 
 
 1033-74 
 
 904-30 
 
 95-70 
 
 33-35 
 
 32-76 
 
 24-36 
 
 5-23 
 
 The Goat 
 
 1033-53 
 
 844-90 
 
 155-10 
 
 55-14 
 
 36-91 
 
 56-87 
 
 6-18 
 
 The Ewe - 
 
 104098 
 
 83232 
 
 167-68 
 
 69-78 
 
 39-43 
 
 51-31 
 
 7-16 
 
 The Bitch . - 
 
 1041-62 
 
 772-08 
 
 227-92 
 
 116-88 
 
 15-29 
 
 87-95 
 
 780 
 
 A full account of the analyses of the milk of these animals 
 by other chemists may be found in the second volume of 
 the translation of Lehmann's " Physiological Chemistry," pp. 
 341 343, and in Bouchardat and Quevenne's treatise, en- 
 titled " Du Lait en general. Des Laits de femme, d'anesse, 
 de chevre, de brebis, de vache en particulier," Paris, 1857. 
 
 (253.) The daily quantity of milk is dependent upon various 
 conditions, such as bodily constitution, food, &c. During the 
 earliest period of lactation the mammary glands secrete less 
 milk than subsequently, the secretion attaining its maximum 
 four or five days after delivery. Lamperierre determined the 
 quantity of milk secreted in definite times by a large number 
 of women, and found, as a mean for each breast, between fifty 
 and sixty grammes in the course of two hours. Assuming that 
 the secretion of milk proceeds at an equal rate during the 
 twenty-four hours, a woman would discharge daily about 
 1320 grammes, or rather more than forty ounces (by weight). 
 Estimating the average weight of a woman at about 134 Ibs., 
 there would be 2*2 Ibs. of milk secreted daily for every 100 
 Ibs. weight of the body. 
 
 A cow, according to the experiments of Boussingault, 
 yields on an average about six kilogrammes of milk daily, 
 and, since on an average a cow weighs 580 kilogrammes 
 there are 1*04 parts (by weight) of milk for every 100 parts 
 
THE MILK. 285 
 
 (by weight) of the cow. Hence, if we know the weight of 
 the cow, we can at once calculate the average quantity of milk 
 that she ought to yield. 
 
 (254.) With respect to the origin of the milk we need Origin of 
 only here remark that none of its leading constituents have 
 been recognised in the blood. We have already shown 
 (p. 106) that the reactions, from which it has been inferred 
 that casein exists in the blood, afford no certain proof that 
 such is the case ; and the same remark holds good with re- 
 gard to the milk-sugar, for both the sugar occurring in the 
 blood and inosite (or muscle-sugar) differ essentially in their 
 physical and chemical characters from milk-sugar. Although 
 it is possible that the fat may pass by transudation from the 
 blood into the milk, we have no evidence that such is the 
 case, and we know that cholesterin, which traverses very 
 readily through some sets of capillaries, does not occur in the 
 milk ; further, it is very questionable whether the butyrin 
 exists in normal blood. Moreover, the salts do not pass into 
 the milk in consequence of simple transudation, for on com- 
 paring the salts of a transudation with those of the milk, we 
 find that the chlorides do not preponderate to nearly so great 
 an extent in the latter as in the former, while the potassium 
 compounds and phosphates are present in the milk in even 
 larger quantities than in the blood-corpuscles.* 
 
 * The following comparative analyses (by Weber), of the ashes of cow's milk 
 and ox-blood distinctly show the above mentioned relations. 
 
 Cow's Milk. Ox-Blood. 
 
 Chloride of potassium . . 14*18 none. 
 
 Chloride of sodium 474 38-82 
 
 Potash .'"' "' : ' Tf . ; ''.-'' i-"; J F~' 23-46 11-44 
 
 Soda *iV$b: : : .: ? VI * . 6-96 29-09 
 
 Phosphoric acid . .^. . .;,.'* 28-40 774 
 
 Lime . 17-34 1-90 
 
 Magnesia . . . 2-20 075 
 
286 
 
 CHAPTER XIII. 
 
 THE SECRETIONS OF THE MUCOUS MEMBRANE 
 AND THE SKIN. 
 
 Mucus. 
 
 Its phy- 
 sical cha- 
 
 Its mor 
 
 photic 
 
 elements. 
 
 Mucus- 
 corpuscles. 
 
 SECTION I. MUCUS. 
 
 (255.) THE term mucus has a somewhat vague significa- 
 tion : it includes not only the secretion of true mucous mem- 
 branes, but also (1.) the contents. of certain cysts occurring in 
 the thyroid gland, the liver, the kidneys, and the ovaries 
 (which, according to Virchow and Rokitansky, yield all the 
 reactions characteristic of pure mucus); (2.) the gelatinous 
 matter of the umbilical cord (which readily becomes converted 
 into mucus) ; and (3.) the contents of certain serous sacs, as 
 for instance the synovial membranes. 
 
 Mucus in its normal state occurs as a tough mass, capable 
 of being drawn up in threads, consisting of a clear viscid 
 fluid containing a number of epithelial cells ; but even per- 
 fectly normal mucus may present many varieties of character, 
 both in reference to its chemical reactions and its morphotic 
 elements, according to the structure of the membrane from 
 which it is secreted. 
 
 (256.) The epithelial cells occurring in mucus may either 
 belong to the tessellated, the cylindrical, or the ciliated 
 variety, and they are so abundant that it is often almost im- 
 possible to distinguish the intercellular fluid in which they 
 are suspended. 
 
 Mucus-corpuscles, which are very similar to the colourless 
 blood-cells and to pus-corpuscles, are always present in normal 
 mucus, although frequently only in very small numbers. In 
 
MUCUS. 287 
 
 inflammatory conditions of the mucous membrane they in- 
 crease to such a degree that, when examined under the mi- 
 croscope, the mucus seems to be entirely composed of these 
 bodies. 
 
 Fibrinous coagula, associated with blood-corpuscles, are 
 constantly found in exudative or croupous inflammations of the 
 mucous membranes. 
 
 In the mucus of the air-passages we often find the so-called Granular 
 inflammatory globules or granular cells. They may occur Ci s ' 
 towards the close of a croupous inflammation, or altogether 
 independently of it ; as for instance in the thick tenacious 
 mucus which is expectorated in the chronic bronchial catarrh 
 of aged persons. 
 
 Fat occurs in almost every kind of mucus, either in the 
 form of globules or of very minute granules : its quantity is 
 much increased in catarrhal affections. 
 
 Molecular granules are seldom entirely absent, and are 
 especially abundant in constitutional diseases, such as tuber- 
 culosis, cancer, and typhus. 
 
 Vibriones and microscopic fungoid growths occur only in 
 mucus in which a process of decomposition is commencing. 
 
 (257.) The most important chemical constituent of mucus j ts c h e _ 
 
 is mucin, which imparts to the mucus its most characteristic m . lcal con " 
 
 stituents. 
 properties. It forms the basis of the mucus, and may be 
 
 obtained by pounding and rinsing the salivary glands, the 
 gelatinous matter of the umbilical cord (the gelatin of Whar- 
 ton), or foetal areolar tissue, with water. It does not coagulate 
 on boiling, is precipitated, without re-solution, by acetic acid 
 and by a solution of alum (the coagula produced by acetic 
 acid appearing under the microscope as fibrinous threads), is 
 precipitated, with re-solution, by the mineral acids, and is not 
 thrown down from these mineral-acid solutions by ferrocy- 
 anide of potassium. It is distinguished from pyin (a sub- 
 stance which it closely resembles, and which will be described 
 in the chapter " On Exudations "), in not being thrown down 
 
288 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 by bichloride of mercury or neutral acetate of lead, and in 
 being precipitated by basic acetate of lead. By prolonged 
 boiling in sulphuric acid (one part of acid in four of water) it 
 yields leucine and more than 4-g- of tyrosine. The only trust- 
 worthy ultimate analysis of mucin is due to Scherer, who 
 found as the mean of three experiments : 
 
 Carbon 
 
 Hydrogen 
 
 Nitrogen 
 
 and, therefore, 
 
 Oxygen 
 
 52-10 
 
 6-97 
 
 12-82 
 
 28-11 
 
 No sulphur was present, but. there was more than 4^ of 
 white ash, which, in addition to much phosphate of lime, con- 
 tained some alkaline carbonates. 
 
 Albumen. Albumen is not present in normal mucus, but appears 
 whenever the mucus membrane assumes an inflammatory 
 state. 
 
 The extractive matters occurring in the mucus have not been 
 carefully examined. They doubtless include the free acids 
 which are frequently found in mucus, and with whose nature 
 we are not acquainted. Indeed, Andral maintains that pure 
 normal mucus is always acid ; but although this assertion may 
 be true, it has not been proved to be so. All that we know 
 is that the ordinary secretions of the mucus membrane are 
 sometimes acid and sometimes alkaline, and that probably 
 the reaction is often due to the admixture of extraneous 
 ingredients. 
 
 Salts. Chloride of sodium is the preponderating mineral ingre- 
 
 dient of mucus; and, in addition to it, we find in the ash 
 alkaline carbonates, a small quantity of alkaline phosphates 
 and sulphates, and some earthy phosphates. The collective 
 salts amount to about 0-7-g- of the mucus. 
 
 Water. The water in mucus ranges from 88-2 to 
 
 Reaction 
 of mucus. 
 
MUCUS. 289 
 
 (258.) Two different theories have been propounded regard- Origin of 
 ing the origin and formation of mucus. Tilanus * argues that 
 wherever true mucus occurs we have a secreting or investing 
 membrane (even in colloid cysts), which is covered with 
 epithelium ; and that further, we always find epithelium in 
 mucus, and that hence there must be a causal connexion be- 
 tween the production of mucus and the formation of epithe- 
 lial cells in short that the cells must be formed from a 
 mucin-containing blastema, or in other words, that the 
 mucus is formed from the blood; the albuminates of the 
 liquor sanguinis, becoming decomposed, under certain un- 
 known conditions, into the structure forming the epithelial 
 cells and into mucus. This view is opposed by Scherer, 
 Virchow, Schrant, and Bonders, who all agree that the mucus 
 is the product of the cells, but who differ on minor points ; 
 the two former holding that the mucus is formed by the 
 gradual solution of the cells, much in the same manner as the 
 gastric juice is formed, while the latter regard the mucus 
 as a product of the metamorphosis of the contents of the epi- 
 thelial cells. There are no chemical grounds for preferring 
 either of these theories to the other. 
 
 SECTION II. SEBACEOUS MATTERS. 
 
 (259.) Under this general title we include not only the Sebaceous 
 product of the sebaceous follicles, which are distributed over 
 the entire skin, but likewise the secretions of the Meibomian 
 and ceruminous glands, the smegma preputii, castoreum, and 
 the vernix caseosa. 
 
 All these secretions abound more or less in morphotic Themor- 
 elements, the matter yielded by the sebaceous follicles being elements, 
 especially rich in small epithelial cells. We also find in 
 
 * De saliva et muco. Arastelodami, 1849, pp. 56 75. 
 U 
 
290 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Their 
 chemical 
 consti- 
 tuents. 
 
 these secretions, especially in the products of the Meibomian 
 and ceraminous glands, peculiar oval or polyhedral cells, 
 varying in diameter from J-Q to T -^- of a line ; which in addi- 
 tion to a pale nucleus with nucleoli, contain minute dark, and 
 clearly defined granules and a few fat globules. If the 
 sebaceous follicles are in a state of inflammation pus-cor- 
 puscles will be found in their secretion. 
 
 A protein-substance, whose exact nature is not known *, 
 occurs in all the above-named secretions. Lehmann found 
 4 of it in the vernix caseosa, 5'6-g- in the human smegma 
 preputii (collected after several operations for phymosis), 
 2*9^ in that of the horse, and 5*8 in Canadian castoreum. 
 
 Neutral fats occur abundantly in these substances. In 
 the vernix caseosa Lehmann found 26'2-g-, in human smegma 
 preputii 47*5$, in that of the horse 49-9^, and in Canadian 
 castoreum 8*2--. 
 
 No volatile fatty acids have been detected in any of these 
 secretions. 
 
 An ammonia-soap is found in the smegma preputii, which 
 also contains a little cholesterin. 
 
 These substances contain only a small amount of mineral 
 constituents, namely, a little chloride of sodium, and hydro- 
 chlorate of ammonia with phosphate of soda and ammonia. 
 Earthy phosphates, on the other hand, are present in con- 
 siderable quantity, amounting, according to Lehmann, to 6 -5 - 
 in the vernix caseosa, 9 '5-g- in the preputial secretion of man, 
 and 5'4-g- in that of the horse. 
 
 The water must naturally vary much in this class of secre- 
 tions ; Lehmann found 66'98-g, and Dr. John Davy 77'87-g- in 
 the vernix caseosa. 
 
 (260.) A few substances still require notice, which must be 
 
 * Being of necessity separated in an insoluble form from the fatty matters 
 with which it is associated, we cannot determine whether it is most similar to 
 albumen or casein. Its behaviour with acetic acid and ferrocyanide of potassium, 
 with strong nitric acid, &c., show that it is a protein-substance. 
 
SEBACEOUS MATTEKS. 291 
 
 regarded either as accidental admixtures or as constituents 
 peculiar to individual secretions. 
 
 Thus alcohol takes up from castoreum a resinous constituent Castoreum. 
 which contains carbolic acid, or hydrated oxide of phenyl 
 (C 12 H 5 . HO), as may be shown by the blue colour which it 
 imparts to a pine shaving saturated with hydrochloric or 
 nitric acid * (see p. 80). 
 
 Salicylous and salicylic acids, probably derived from the 
 willow-bark on which the animal feeds, are also found in 
 castoreum (Weber). 
 
 The preputial secretion of the horse and castoreum con- 
 tain hippuric and often benzoic acids. 
 
 In fresh castoreum we can recognise with the microscope 
 crystals of sulphate of lime and in the preputial smegma of 
 the horse crystals of oxalate of lime.f 
 
 * Lehmann observes, that as the resinous constituents of castoreum coincide 
 remarkably with those of hyraceum (which he believes to be the dried intestinal 
 excrement of Hyrax capensis, and not a urinary product, as was formerly sup- 
 posed), and as carbolic acid occurs in both these substances, it seems most 
 probable that they are not products of the metamorphosis of tissue, or that 
 they are any peculiar secretion, but merely derivatives of the resinous substances 
 occurring in the food. 
 
 f In connexion with the subjects noticed in this section, we may allude to the 
 peculiar secretions yielded by the cutaneous glands of certain reptiles. These 
 glands in Lacerta salamandra yield, according to Gratiolet and Cloez, a white 
 fluid of the consistence of rich milk, which very rapidly coagulates ; it has an 
 acid reaction, and an acrid and repulsive odour. Birds, mice, and guinea-pigs, 
 when inoculated with it, were attacked with convulsions, but seldom died. The 
 secretion of Rana bufo (the common toad), appears to possess similar but more 
 powerful properties ; birds when inoculated beneath the wings, dying in five 
 or six minutes without convulsions, even after the matter had been dried and 
 mixed with an alkali, an apoplectic effusion being found in the cerebellum. 
 Dr. John Davy, by pressing the cutaneous follicles of the same reptile has 
 obtained a thick fluid, of which the part soluble in water and alcohol yielded 
 on evaporation a pale yellow neutral substance, which on application to the 
 skin excited pain, fused on being heated, but did not give off any ammoniacal 
 odour, and dissolved in nitric acid with a purple colour. Hautz has examined 
 the fluid which Bufo cinereus can eject from the cutaneous glands, when irri- 
 tated. He found that it was alkaline, and that the greater part of the solid 
 residue, which did not exceed 0'5g, was urea. No uric acid could be detected. 
 The above brief and incomplete notices show that the subject requires further 
 
 u 2 
 
292 
 
 PHYSIOLOGICAL CHEMISTBY. 
 
 SECTION III. THE SWEAT. 
 
 The sweat. (261.) The sweat as it exudes from the open mouths of the 
 ducts of the sudoriparous glands, and collects upon the skin 
 of a person who is perspiring freely, is> as is well known, 
 a colourless and very watery fluid, with a rather saltish taste, 
 and usually evolves a very characteristic odour, which varies 
 with the cutaneous surface from which it has exuded. It 
 normally has a faintly acid reaction ; but sweat that has been 
 collected from the axillae or from the feet is often found to be 
 alkaline. 
 
 The best method of collecting -sweat for chemical examina- 
 tion is that adopted by Schottin and Funke. The arm (the 
 organ most conveniently operated on) is enclosed in a tolerably 
 loose caoutchouc sleeve, which grasps the limb tightly above, 
 while below it communicates with a small flask in which the 
 fluid collects. 
 
 Normal sweat usually contains a considerable amount of 
 epithelium, which gives it, when viewed in large quantity, 
 a turbid, almost milky appearance. According to Funke the 
 epithelium ranges from 0*191 to 0*307^ of the sweat, and it 
 seems to be increased in a direct ratio with the intensity of 
 the secreting action. 
 
 The solid non-volatile constituents of sweat range from 
 0*7 to 2-6-g- (Funke). The chlorides of sodium and potassium 
 make up more than half of this solid residue. 
 
 Neither alkaline phosphates nor ammonia-salts occur in 
 the sweat ; but ammonia is rapidly developed in decomposing 
 sweat. The earthy phosphates and peroxide of iron, which 
 always occur in the ash, are due solely to the epithelium. 
 
 investigation. An examination of the secretion of the anal glands of the pole-cat, 
 skunk, &c., might also lead to very interesting results. I am not aware that 
 any chemist has yet ventured on the task. 
 
 Its mor- 
 
 photic 
 
 elements. 
 
 Its che- 
 mical con- 
 stituents. 
 
THE SWEAT. 293 
 
 According to Funke the salts vary from 0*246 to 0'629 of 
 the fluid. 
 
 Although some of the fat contained in the sweat is due to 
 the sebaceous follicles, a portion is undoubtedly yielded by 
 the sudoriparous glands ; for the sweat obtained from the 
 palm of the hand, which contains no sebaceous glands, always 
 contains a little fat. 
 
 Volatile fatty acids form the principal part of the organic Fatty acids, 
 matters held in solution in the sweat. Lehmann has proved 
 that these acids originate from the sweat-glands by showing 
 that the fat of the sebaceous glands, when saponified, yields 
 hardly a trace of them. Of these acids the most abundant is 
 formic acid, while there is a smaller quantity of acetic acid and 
 still less of butyric acid. The presence of metacetonic and 
 capric acids is also probable, but has not been definitely proved. 
 
 Lactic acid, which was long regarded as an ingredient of Lactic acid, 
 sweat, does not exist in that fluid. A peculiar nitrogenous 
 acid, termed hydro tic or sudoric acid (C io H 8 NO ]3 ) has been 
 described by Favre * as occurring in sweat, but its existence is 
 very doubtful. 
 
 Urea occurs in small quantities in the sweat, and in some Urea, 
 renal affections, especially in ursemiay is very abundant, es- 
 pecially in the sweat of the face. Funke has carefully 
 studied the relations of urea to the sweat, and has ascer- 
 tained that, as in the case of the urine, the quantity of urea 
 is dependent to a certain degree on the quantity of water that 
 is yielded by the sudoriparous glands, and that after prolonged 
 sweating the quantity of urea in the sweat is much diminished. 
 In one experiment he found that the sweat yielded by the 
 whole body in one hour was 215-067 grammes or nearly 7 
 ounces, and that it contained 0'423 of a gramme, or about 
 
 * As Favre entirely overlooks the existence of volatile acids in the sweat, 
 and as he determines quantitatively the lactic acid which, as Schottin, Funke, 
 and others have proved, does not occur in sweat, we may well have doubts 
 regarding his new acid. 
 
 u 3 
 
294 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Uric acid. 
 
 Sugar. 
 
 7*5 grains of urea; this would be at the rate of 180 grains 
 in a day if the sweating continued uniformly. In another expe- 
 riment (both were made upon himself) the sweat in one 
 hour amounted to 561 '765 grammes or nearly 18 ounces, 
 containing 0-629 of a gramme, or 9'7 grains of urea ; if the 
 secretion went on at this rate for twenty-four hours nearly 
 half an ounce of urea would be given off daily by the skin. 
 The quantities found by Funke considerably exceed the 
 amount previously found by Picard and other observers. 
 
 Uric acid is reported to have been found in the sweat in 
 two or three cases (Wolf, Hamernjk). Schottin could find 
 no trace of it in uraBmic sweat, and even its occasional 
 presence is doubtful. 
 
 Sugar has been detected in the sweat in cases of diabetes 
 by several good chemists, while others (Hoefle and Lehmann) 
 have sought in vain for it. With the view of seeing whether 
 sugar would pass from the digestive organs into the sweat, 
 Schottin swallowed more than a pound of milk-sugar in thirty- 
 six hours; the whole of the sweat collected in six hours 
 yielded, however, no trace of sugar. 
 
 Pigments. We know little or nothing with certainty regarding the 
 colouring matters occurring in the sweat. Schottin often 
 extracted a bright red colour by means of alcohol. In 
 jaundice the bile-pigment sometimes enters the sweat and 
 communicates a yellow tint to it. 
 
 (262.) Schottin has instituted various experiments regard- 
 ing the passage of certain acids, salts, &c., into the sweat, 
 and finds that tartaric, succinic, and benzoic acids pass in 
 the course of five hours into the sweat, while iodide of 
 potassium, taken daily to the extent of half a drachm, could 
 not be detected in that fluid till the fifth day. Neither salicin 
 nor quinine re-appeared in the sweat. After the ingestion 
 of cinnamic acid, either its salts or those of benzoic acid 
 (but which of the two Schottin could not determine) occurred 
 in the sweat. The salts of tellumim, when taken internally, 
 
 The pas- 
 sage of 
 various 
 substances 
 into the 
 sweat. 
 
THE SWEAT. 295 
 
 communicate to the cutaneous excretion the fetid odour pecu- 
 liar to those substances. 
 
 Certain gases, especially carbonic acid and nitrogen, are 
 simultaneously exhaled with the liquid secretions of the sudo- 
 riparous glands ; the ratio in which the above-named gases are 
 excreted is variable, but most commonly about two volumes 
 of carbonic acid are excreted for one volume of nitrogen. 
 
 (263.) The amount of the sweat has been more accurately Its amount, 
 determined by Funke than by any previous observer. In 
 twenty-two experiments on himself and two of his students 
 (each experiment ranging from one to two hours) he found 
 that the quantity of sweat secreted by the whole body in one 
 hour varied under different conditions (from quiet movement 
 in a room to violent exercise in the sun) from 53 to 815-3 
 grammes (or from 13 -5 drachms to 2 5 '5 ounces) ; the maximum 
 and minimum quantity of solids contained in it being O923 
 and 6 -96 7 grammes, or from 14 to 107 grains. He found, as 
 indeed common experience shows us, that the amount of 
 sweat varies very much in different persons exposed to the 
 same external conditions: thus, for instance, in two sets of 
 parallel experiments on himself and two of his students, the 
 relative quantities of sweat in an hour were 1 I 2*3 \ 4-4, 
 and 1 : 1-7 : 2-06. 
 
 u 4 
 
296 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 CHAPTER XIV. 
 
 THE URINE. 
 
 The urine. (264.) THE urine is a fluid which is secreted by the kidneys 
 from the blood, and it is the principal means through which 
 the soluble debris of the organism, especially the nitrogenous 
 and saline matters, are eliminated from the system. It is a 
 very complex fluid, and its composition varies very conside- 
 rably in different classes of animals. We shall, in the first 
 instance, confine our remarks to the urine as it occurs in 
 man. 
 
 Healthy human urine, when freshly passed, is a clear fluid 
 of a bright amber colour, a bitter saltish taste, and a peculiar 
 aromatic odour. It is always heavier than water, its ordinary 
 specific gravity ranging from 1*015 to 1-025, and in a state of 
 health it probably never exceeds 1-030. Its normal reaction is 
 acid, but the degree of acidity varies considerably. 
 
 (265.) If urine is placed in a perfectly clean vessel it does 
 not exhibit any great proneness to decomposition. As it 
 cools it generally deposits a slight cloudy sediment, which 
 sinks very slowly, and is most obvious in the morning urine, 
 which has been retained for some time in the bladder. After 
 standing for some days exposed to the air at an ordinary 
 temperature, we find that its reaction becomes more acid, 
 and red or yellow crystals of uric acid, visible to the naked 
 eye, are deposited in the mucous sediment and on the walls 
 of the vessel ; and the urine will often remain in this con- 
 dition for weeksVithout further decomposition. If the urine 
 is of low specific gravity, or if the temperature is higher than 
 usual, this acid fermentation is rapidly replaced by another 
 
THE URINE. 297 
 
 decomposition, in which the fluid is first covered with a thin, 
 glistening, and often iridescent pellicle, fragments of which 
 gradually break off and sink to the bottom. The mucous 
 sediment then becomes interspersed with dirty yellowish-white 
 flakes ; the urine becomes paler, assumes an alkaline reaction, 
 and begins to develope a fetid ammoniacal odour. The red 
 or yellow crystals are now replaced by white amorphous 
 granules and colourless strongly refracting prismatic crystals 
 of phosphate of ammonia and magnesia (triple phosphate). 
 
 (266.) The morphotic elements of the urine are compara- Its mor- 
 tively few. Indeed, healthy urine, when freshly passed, pre- elements, 
 sents merely a few scales of pavement epithelium derived 
 from the mucous coat of the bladder. Urine, however, that 
 has stood for some time, or that deviates from the normal 
 type, may present, as organic morphotic constituents, mucus- 
 and pus-corpuscles, cylindrical casts or tubes, spermatozoa, 
 blood-corpuscles, coagula of fibrin, and certain fungi and 
 infusoria, while the unorganised constituents are the urates, 
 uric and hippuric acids, phosphate of ammonia and magnesia, 
 earthy phosphates, oxalate of lime and cystine. We postpone 
 the consideration of these sediments till we have discussed 
 the general chemistry of the urine. 
 
 (267.) The most important constituent of the urine is urea, Urea, 
 a substance which we have already so fully considered that 
 little remains to be added here. 
 
 Since the earlier part (pp. 37 49) of this volume was 
 printed, additional observations, confirmatory of those ^of 
 Lehmann, Beigel, &c., have been made in reference to the 
 influence of diet on the excretions of urea. 
 
 Thus Warncke * (as a preliminary to his researches on the 
 amount of urea excreted in typhoid fever) ascertained that 
 
 * See his Essay " On the Amount of Urea-excretion in Typhoid Fiver." 
 Translated from the Danish by Dr. W. D. Moore, and published in the Dublin 
 Medical Press, 1859, vol. xlii. pp. 4952 and 6569. 
 
298 PHYSIOLOGICAL CHEMISTRY. 
 
 the average quantity of urea eliminated in twenty-four hours 
 is 
 
 For an adult man upon mixed diet 33-7 grammes 
 
 vegetable diet 25-3 
 
 woman upon mixed diet 26-8 
 
 vegetable diet 20*1 
 
 These are the average results of seven examinations for each 
 individual. 
 
 Similarly Professor Haughton finds that " well-fed, flesh- 
 eating, wine-drinking men ''" yielded, on an average, 576 
 grains (or 37*4 grammes), while <( well-fed, water-drinking 
 vegetarians" yielded only 394 grains (or 25-6 grammes). 
 
 Eecent observations by Grenth and others show that the 
 quantity of urea increases with the quantity of water that is 
 carried off by the kidneys. Thus, for example, if a man 
 passes 1000 grammes of urine daily, containing 33 grammes 
 of urea, he will pass about 42 grammes, if the quantity of 
 his urine is raised to 2000 grammes, by copious water-drink- 
 ing, and about 50 grammes if the urine rises to 3000 
 grammes. 
 
 To the remarks which have been previously made (see p. 
 45) on the influence of disease in modifying the amount of 
 urea we may add the following. In intermittent fevers it 
 has been found (by Moos, Traube, and Eedtenbacher) that, 
 during the paroxysm, the secretion of urea and of urine gene- 
 rally is absolutely increased, while in the period of inter- 
 mission there is a diminution both of the urea and of the 
 urine generally. In the cold and hot stages about 3*5 times, 
 and in the sweating stage about 0*5, more urea are secreted 
 than in the period of intermission. 
 
 Warncke's investigations in reference to typhoid fever are 
 of such importance that we shall borrow freely from his 
 memoir. " The urine of a patient labouring under typhoid 
 fever is not distinguishable by external characters from any 
 
THE URINE. - 299 
 
 other. It may be pale, may be excreted in large quantity, 
 and may be clear or may be turbid, opaque, deposit a copious 
 sediment, and be secreted in small quantity (which is parti- 
 cularly the case in the commencement of the disease) ; but its 
 special characteristic is that it contains an absolute and re- 
 lative increase of urea. 
 
 This property is retained by the urine through the stages 
 to which the disease may be said to increase ; when, on the 
 contrary, the latter diminishes, the amount of urea is likewise 
 lessened, and the quantity continues smaller after the end of 
 convalescence, until the restitution of the body is completely 
 effected. 
 
 The following table exhibits the average numbers of more 
 than fifty investigations (on thirty men and twenty women), 
 which were repeated daily during the stay of the individuals 
 
 in the hospital : 
 
 Males. Females. 
 
 In the first week , , 43-2 grammes . 34-0 grammes 
 
 second,, .... 39-9 . 30-2 
 
 third \. 30-9 . 24-1 
 
 fourth . 23*2 . 20-5 
 
 If these numbers be compared with those representing the 
 quantity of urea which is normally excreted, especially under 
 the use of vegetable food, and there are very few patients 
 that use even it, it must be allowed that increase of the 
 quantity of urea is a constant phenomenon in typhoid fever. 
 This character, however, is not peculiar to typhoid fever, for 
 in many other acute diseases, as in pneumonia, pleurisy, 
 rheumatic fever, &c., the quantity of urea is increased ; but 
 in all these the other organic constituents of the urine are 
 simultaneously augmented, while this takes place with the 
 urea in a less degree. We cannot attach too much importance 
 to this circumstance. An increased quantity of organic 
 matters in general indicates an augmented supply of com- 
 bustible materials ; but an increased quantity of urea without 
 
300 PHYSIOLOGICAL CHEMISTRY. 
 
 any simultaneous augmentation of the other organic com- 
 pounds in the urine, as is the case in typhoid fever, points, on 
 the contrary, to a more energetic combustion." Warncke goes 
 on to show that the increase of the quantity of urea is not 
 equally great in all typhoid fevers, and that it varies directly 
 with the height of the temperature, the rapidity of the pulse, 
 and the degree of emaciation. 
 
 A diminution of the quantity of urea, though never to a 
 degree below the normal standard, occasionally (but only 
 seldom) took place ; it was especially observed after violent 
 haemorrhage from the bowels, and when there was consider- 
 able enlargement of the spleen.* 
 
 In many cases the patients, during the entire course of the 
 disease, took food regularly; but "in none of them was the 
 consumption of food followed by an increased quantity of 
 urea. 
 
 Warncke lays great stress on the value of the determination 
 of the urea in reference to differential diagnosis. " When I 
 find," he observes, "the increase of urea without any augmen- 
 tation of the other organic constituents of the urine to be 
 peculiar to typhoid fever, I am easily led to seek in this 
 fact a diagnostic sign between this affection and the diseases 
 which in other symptoms resemble it, especially gastric fever 
 and meningitis." 
 
 In gastric fever he found that the quantity of urea was not 
 very different from what is excreted by healthy persons when 
 
 * Warncke connects the enlargement of the spleen and the diminution of 
 the urea in the following manner. He holds Fuhrer's view (see p. 47), that the 
 urea is derived from the blood -corpuscles, and believing that the spleen is the 
 organ in which the blood-corpuscles should be changed into urea and uric acid, 
 he maintains that the augmentation of the volume of the spleen in these cases is 
 due to the proper metamorphosis not taking place, and to the consequent accumu- 
 lation of blood-corpuscles in that organ. In his investigations regarding the 
 function of the spleen, he arrived at the singular fact that although dog's urine 
 never contains uric acid, this substance occurs in the spleen of that animal. 
 
THE URINE. 301 
 
 living on a vegetable diet. From an extended series of 
 analyses lie obtained the following mean numbers : 
 
 Males. Females. 
 
 For the first week . 22-1 grammes . 18'0 grammes 
 
 second . 24-2 . 19-8 
 
 third . 25-7 . 20-4 
 
 Thus we have here the reverse of what occurs in typhoid 
 fever. The quantity of urea is less in the first weeks than 
 during convalescence. 
 
 In meningitis the differences in relation to the amount of In menm- 
 urea are at least equally marked, according to Warncke. In gltis * 
 a boy aged seven years, who died from meningitis, the mean 
 daily quantity of urea was 6 -4 grammes,, while in^a boy aged 
 eight years, who died from typhoid fever, the minimum 
 quantity of urea was 11 -9 grammes. Heller (see p. 45) 
 mentions meningitis as a disease characterised by an excessive 
 excretion of urea. If Warncke's views are correct, it is pos- 
 sible that in Heller's cases there was an error in diagnosis.* 
 
 In diabetes there seems (from the investigations of Thier- In dia- 
 felder and Uhle) to be a definite ratio between the daily quan- 
 tity of nitrogenous food and the daily excretion of urea. 
 
 The modes of testing for urea have been fully described in 
 pp. 38 41. Attempts have been made to calculate formulse 
 connecting the percentage of urea in urine with the specific 
 gravity ; even the best give only rough approximations to the 
 truth.f 
 
 * Heller does not stand unsupported in his statement regarding the excess 
 of urea in meningitis. Moos relates the case of a man with meningitis, in 
 whom the daily urea (the average of five days) amounted to 41-2 grammes. 
 
 t Professor Haughton has given a diagram representing the curve of urea in 
 man, in cases in which neither albumen nor sugar is present. If x represent 
 the excess of the specific gravity ahove 1000, and y, he the number of grains 
 of urea in a fluid ounce of urine, its equation is (28 xf = 28(14-#), which 
 shows that it is a parabola. Let (for example) the specific gravity be 1-018, 
 then x = 18, and the equation gives us y = 10-5 grains. He considers the 
 
302 PHYSIOLOGICAL CHEMISTRY. 
 
 (268.) Uric acid is for the most part in combination with 
 soda, and exists in normal human urine in only very small 
 quantity, seldom forming more than Ol-g-. An adult usually 
 discharges from 0-3 to 0-9 of a gramme daily, the most com- 
 mon quantity being about half a gramme or seven or eight 
 grains.* Although the amount of uric acid does not vary 
 with the nature of the food to the same amount as that of the 
 urea, yet the nature of the diet does to a certain extent 
 modify its quantity. Thus, for instance, Professor Haughton 
 found that the mean daily quantity of uric acid excreted by 
 beef-eaters and wine-drinkers was 4 '5 grains, the maximum 
 being 11-9 grains, and the minimum 0*7 of a grain, while 
 vegetarians yielded on an average only 1*48 grains, part of 
 which was hippuric acid. His investigations on this subject 
 led him to the rather startling view that <( no uric acid what- 
 ever should occur in the urine of man in perfect health, but 
 that all the nitrogen of the urine should pass off in the form 
 of urea, a more highly oxidated product than uric acid." 
 There are several facts which support this view, amongst 
 which we may notice, first, that of the urine of the dog con- 
 taining no uric acid while that substance occurred in the spleen 
 (see p. 300) ; and, secondly, that there is certainly no fixed 
 proportion (although they generally occur in an inverse ratio) 
 between the quantities of uric acid and urea. Kanke, for in- 
 stance, found the ratio to vary from 1 : 50 to 1 I 80. The ex- 
 cretion of this substance seems to have no definite connection 
 
 following bed-side rule sufficient for ordinary purposes : " Half the excess of 
 the specific gravity of urine (not containing either sugar or albumen) above 
 1000 is the number of grains of urea per fluid ounce." 
 
 * Kaupp found that on a mixed diet, and taking little exercise, he excreted, 
 on an average, 0*519 of a gramme ; Genth found, under similar conditions, 
 that he excreted, on an average, 0-565; Neubauer found 0'28 as an average of 
 five days, on two healthy men, and 0'49 as an average of eight days ; and 
 Ranke found 0'629 as a mean of twenty observations made upon himself; 
 these give a daily mean of about half a gramme, or between seven and eight 
 grains of uric acid. 
 
THE URINE. 303 
 
 with the age, sex, or weight of the patient, and not much 
 even with the food. We have shown (see p. 8) that there 
 are good reasons for attributing the presence of oxalic acid in 
 many cases to imperfect oxidation of the blood. Similar 
 reasons seem to apply here ; and they are supported, to a 
 certain extent, by Dr. Hammond's experiments described in 
 p. 66, and by the other facts mentioned in the same para- 
 graph. In addition to the general remarks in p. 67 on the Augmen- 
 conditions of the system which give rise to an augmentation ^f^j 
 of the uric acid, we may mention that it is constantly 
 increased in leucsemia accompanied with enlargement of the 
 spleen, in intermittent fever on the days of the paroxysms, 
 and for some days after the attacks have ceased (Ranke). In 
 chronic gout the quantity of uric acid in the urine is much 
 diminished, the total average of all Dr. Garrod's analyses in 
 these cases being far under a single grain * ; in acute gout the 
 daily excretion of uric acid is not necessarily increased, and in- 
 deed is often much diminished ; in seven cases detailed by Dr. 
 Grarrod the total average of all the analyses was 3-62 grains.f 
 
 Grenth has made the following singular observation regard- influence 
 ing the influence of water (taken as a drink) on the excretion of water 
 of uric acid. Living on his ordinary mixed diet and not 
 drinking much water he excreted daily 0-324 of a gramme of 
 uric acid ; living on the same food and drinking 1000 c. c., or 
 about 35 fluid ounces of water, he excreted only 0'396 of a 
 gramme ; drinking 2000 c. c., or about 70 ounces of water, he 
 excreted mere traces; and when drinking 4000 c.c., or 140 
 ounces of water, he excreted no uric acid whatever ; in these 
 experiments the urea rose in an inverse proportion from 46-6 
 grammes to 52 ! grammes. 
 
 According to Ranke, sulphate of quinine has a marked in- of quinine, 
 fluence in checking the excretion of uric acid. As a mean of 
 
 * On the Nature and Treatment of Gout. London, 1859, p. 175. 
 f Op. cit. p, 163. 
 
304 PHYSIOLOGICAL CHEMISTRY, 
 
 20 experiments he found that 20 grains of quinine reduced 
 the uric acid of the succeeding 24 hours from 0*629 to 0-271 
 of a gramme. 
 
 Its micro- The microscopic characters and the chemistry of uric acid 
 chaSers bave been alread 7 sufficiently noticed in pp. 6365. We 
 will merely add a description of the best method of deter- 
 mining the amount of this constituent in urine. Hydro- 
 chloric, nitric, or acetic acid may be used to precipitate the 
 uric acid from the urine. If the urine contain no albumen 
 nitric acid is preferable to hydrochloric, because uric acid is 
 less soluble in the former than in the latter, and because the 
 latter is believed to favour the acid fermentation, and the 
 development of minute fungoid growths which tend to decom- 
 pose the urates. Dr. Thudichuni recommends that after the 
 acid has been added, the urine shall be exposed to a tempe- 
 rature of 98 F. (on a sand-bath, for instance), which has the 
 double advantage of forming much larger crystals than are 
 produced at an ordinary temperature, and of preventing the 
 deposition of any urates, which are not so easily acted upon 
 by the acid as when they are in solution. The mixture 
 should stand for from twenty to forty-eight hours, after which 
 the crystals may be collected, washed, and weighed on a filter 
 whose weight has been previously determined. 
 
 Hippuric (269.) Hippuric acid is now ranked amongst the ordinary 
 constituents of healthy human urine. 
 
 We may here add a few remarks to the description we have 
 already given (pp. 57 59) of the occurrence of this acid in 
 the system ; essays upon hippuric acid having been recently 
 published by Weissmann and Hallwachs. 
 
 From observations made upon himself Weissmann is led to 
 the conclusion that the hippuric acid which occurs in human 
 urine is in part a product of the metamorphosis of the tissues, 
 and is in part formed directly from certain kinds of vegetable 
 foods (whose exact nature however he has not determined). 
 He always found hippuric acid in his urine, and more was 
 
THE URINE. 305 
 
 present during a mixed diet than when he lived on a purely 
 animal diet (of fifteen eggs and a pound of meat daily). That 
 it is formed independently of vegetable food is obvious from 
 its occurring in the urine of typhous patients, (who during the 
 preceding fortnight, or even month, had taken nothing but 
 milk and broth,) in about the same quantity as in his own 
 urine during an animal diet. On a mixed diet, he excreted 
 daily 2-17 grammes, or 33-4 grains, and on a purely animal 
 diet, only 0-79 of a gramme or 12 grains. It is probable that 
 these numbers are much higher than would be generally found. 
 Several years ago I made numerous analyses in reference to 
 this constituent, but never, unless after the ingestion of ben- 
 zoic acid, found such an amount in healthy urine as that 
 given by Weismann. Duchek and Hofle deny that hippuric 
 acid is a constant constituent of human urine, and Professor 
 Haughton only met with it once in the urine of ten men, and 
 in this case the fluid had a remarkable smell, compounded of 
 that of sweet hay and apple-juice. 
 
 Weismann found that the quantity of hippuric acid was 
 diminished in febrile diseases, pneumonia, intermittent fever, 
 and in three cases of diabetes. He ascribes the diminution in 
 the febrile cases to the abnormal rapidity of the metamor- 
 phosis of the tissues, and to an increased excretion of carbon 
 by the lungs, while in the cases of diabetes he refers it to the 
 exclusive animal diet : his observations are however in direct 
 opposition to those of Lehmann, who found an excess of 
 hippuric acid both in diabetes and in fever. 
 
 Kiihne* has established the singular fact that no traces of 
 hippuric acid can be detected in the ordinary urine in jaun- 
 dice. Even when benzoic acid was given to jaundiced 
 patients, or to dogs to which jaundice had been artificially 
 induced, no hippuric acid, but only benzoic acid, appeared 
 in the urine. 
 
 * Contributions to the Pathology of Icterus; translated in Beale's Archives 
 of Medicine, vol. i. pp. 342 352. 
 
306 PHYSIOLOGICAL CHEMISTRY. 
 
 Hallwachs has especially devoted his attention to the 
 origin of the hippuric acid in the herbivorous animals. He 
 first ascertained that grass and hay contain not only no ben- 
 zoic acid, but no member of the benzoyl series that could 
 produce benzoic acid in the system, and which by conjugation 
 with glycine could yield hippuric acid, and he afterwards 
 found that neither cumarin nor chlorophyll is converted in 
 the system into hippuric acid. Hence he was led to the 
 view regarding its origin which is propounded in p. 59, and 
 which is further strengthened by recent experiments of 
 Stadeler on the gradual oxidation of albuminous substances. 
 
 The best method of searching for hippuric acid in human 
 urine, is to evaporate three or four ounces of the fluid in the 
 water bath to the consistence of a. syrup, to extract the residue 
 with alcohol, and to filter. The solution thus obtained con- 
 tains the hippuric acid with urea, &c. We add a little 
 oxalic acid to fix the urea, evaporate to the consistence of a 
 syrup, and extract the residue with ether containing a little 
 alcohol. The ethereal solution which contains the hippuric 
 acid must be evaporated nearly to dryness, boiled with water, 
 and filtered while hot. On cooling, or by slow evaporation, 
 we get the acid in its characteristic crystallised form (Plate 
 III. fig. 1). 
 
 Xanthine. (270.) Xanthine now deserves a fuller notice than it re- 
 ceived in p. 50. Since the earlier part of this volume was 
 printed, it has been discovered by two excellent chemists, 
 Scherer* and Streckerf, that xanthine is present, although in 
 very small quantities, in normal human urine. Scherer has 
 likewise found it in the brain, the spleen, the pancreas, and 
 the liver of the ox ; in the thymus gland of the calf ; in the 
 muscular tissue of the horse, the ox, and of fishes, as well as in 
 the liver in acute yellow atrophy of that organ. According to 
 ThudichumJ it is a normal constituent of the human liver. 
 
 * Ann. d. Ch. u. Phann. 1858, rol. cvii. p. 314. 
 
 f Ibid. 1858, vol. cviii. p. 151. 
 
 j Medical Times and Gazette, Dec. 4, 1858. 
 
THE URINE. 307 
 
 Uric acid, xanthine, and hypoxanthine form a closely allied 
 physiological as well as chemical group. The two former 
 occur simultaneously not only in the urine, but in the spleen, 
 the liver, and the brain, while xanthine is not only invariably 
 accompanied (according to Scherer) by larger or smaller 
 quantities of hypoxanthine, but as Strecker has shown hypo- 
 xanthine can be made by the action of nitric acid to yield a 
 product from which xanthine (in place of hypoxanthine) may 
 be obtained by a process of reduction. Xanthine (C 10 H 4 N 4 4 ) 
 must be regarded as a higher stage of oxidation of hypoxan- 
 thine (C 10 H 4 N 4 2 ) and a product of the regressive metamor- 
 phosis of the tissues, which in the ordinary condition of the 
 system is excreted in a more highly oxidised form as urea, 
 uric acid, &c. 
 
 The quantities in which xanthine occurs are so trifling, 
 and the chemical difficulties of searching for it are so con- 
 siderable, that we shall not attempt to describe its tests ; 
 and the same remark applies to the following substance. 
 
 (271.) Hypoxanthine (see p. 50) has been found by Scherer Hypo-- 
 and Strecker to be constantly associated with xanthine, not 
 only in the urine, but in almost all the animal fluids ; in the 
 blood, in the muscular tissue of mammals and fishes, in the 
 juice of the spleen, kidneys, and liver, in the pancreas, 
 the thymus and the thyroid glands, and the brain. Its 
 chemical affinity to xanthine has been shown in the pre- 
 ceding paragraph. We are justified in inferring that hypo- 
 xanthine, which in pathological states is found in certain 
 organs in large quantity, is in the normal condition of the 
 organism converted for the most part into xanthine, which 
 again is usually further oxidised into uric acid, urea, &c. 
 
 (272.) Allantoine is a probable constituent of the urine Allantoine. 
 in cases of impeded respiration (see p. 49). According to 
 Schottin it occurs in the urine after large doses of tannin. 
 
 (273.) Creatinine and creatine must be mentioned amongst Creatinine 
 the constituents of urine, although it is probable that the tine 
 
 x 2 
 
Creatinine 
 of 24 hours. 
 
 Creatine 
 of 24 hours. 
 
 9-66 grains. 
 
 6 '3 2 grains. 
 
 5-61 
 
 4-68 
 
 6-00 
 
 3'67 
 
 b'ol 
 
 4-77 
 
 5-66 
 
 3-45 
 
 8-76 
 
 4-36 
 
 308 PHYSIOLOGICAL CHEMISTRY. 
 
 latter may merely be a product of decomposition of the 
 former yielded during the process of extraction. 
 
 The only observations on the amount of the daily excretion 
 of these substances which (as far as I know) have yet been 
 published, are those of Thudichum. Two men, each aged 
 28 years, and weighing between ten and eleven stone, were 
 the subjects of the experiments recorded in the following 
 table : 
 
 Number of days 
 observed. 
 
 f 5 
 A J 4 
 
 I 5 
 
 {2 
 5 
 5 
 
 Nothing is known regarding the excretion of these sub- 
 stances in disease. 
 
 Formic (274.) Formic acid is sometimes present in very small 
 
 quantities in the urine of healthy persons (see p. 11). The 
 administration of amygdaline to rabbits either into the sto- 
 mach or directly by injection into the veins, causes this acid 
 to appear in the urine in considerable quantity (Ranke). 
 
 Lactic Lactic acid is so commonly regarded as a normal con- 
 
 stituent of the urine, and indeed so often actually occurs in 
 that fluid, that although it is in reality only an abnormal 
 ingredient, we shall notice it here. Lehmann has very 
 carefully investigated this subject, and the conclusions at 
 which he has arrived have been already given in p. 22 in 
 our remarks upon " Lactic Acid." It has been proved by the 
 investigations of Boussingault, Robin and Verdeil and others 
 to exist in considerable quantity in the urine of the horse 
 and cow, and in that of pigs when fed upon potatoes. 
 
 Butyric Butyric acid is sometimes found in small quantities both 
 
 acid. J 
 
THE URINE. 309 
 
 in healthy and in morbid urine, especially in the urine 
 during pregnancy, and shortly after delivery. 
 
 (275.) Trimethylamine, a basic body, homologous with Trime- 
 ammonia, and in which the three equivalents of hydrogen of t ly a 
 the ammonia are replaced by three equivalents of methyle, 
 (C 2 H 3 ) has been obtained by Dessaignes and subsequently by 
 Buchheim from the urine, but it should probably be merely 
 regarded as an accidental product of decomposition.* 
 
 (276.) Extractive matters, or, in other words, the collective Extractive* 
 substances of whose individual composition we have no 
 accurate chemical knowledge, occur in the urine in very 
 variable quantities ; and they are usually increased in most 
 diseases. They are doubtless somewhat indefinite products of 
 metamorphosis of the tissues. They are, according to the 
 researches of Scherer, excreted far less abundantly in re- 
 ference to their weight, by children than by adults, children 
 from 4 to 7 years for every thousand parts by weight, yield- 
 ing daily 0*156, while an adult yields 0*3 8 6. f In prolonged 
 starvation the extractive matters of the urine are much in- 
 creased, and exceed the urea in quantity. 
 
 Included in these extractive matters are the damaluric 
 acid and damolic acid (see p. 17), the hydrated oxide- of 
 phenyl (phenylic or carbolic acid) and the hydrated oxide of 
 tauryl(or taurylic acid) (see pp. 80 81) a series of volatile 
 acids obtained by Stadeler by means of distillation, from the 
 
 * Hofmann, the discoverer of this volatile alkaloid or base (C 6 H 9 N), has 
 shown that it exists in the brine of pickled herrings, to which one of its salts 
 gives its peculiar flavour. He supposes that it is formed by some kind of 
 putrefaction of an acrid compound contained in the fish. It has likewise been 
 obtained by C. Schmidt from the alcohol-extract of the retina. 
 
 t Similar experiments which do not altogether confirm those of Scherer, have 
 been made by Hummel, who found that a boy aged three years excreted 0-232 of 
 extractive matters in twenty- four hours for 1000 parts by weight ; a boy aged 
 four years 0-294 ; a girl aged five years 0-410 ; a youth aged eighteen years 
 0-195 ; and a man aged sixty-five years 0-382. In both sets of experiments 
 the extractive matters included mucus, uric acid, &c., in short everything solid 
 but urea, and fixed salts. 
 
 x 3 
 
310 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Urine 
 pigments. 
 
 Indigo. 
 
 urine of the cow, the horse, and man ; and which, if they 
 really exist in the urine and are not formed by chemical pro- 
 cesses, are probably the main cause of the peculiar odour of 
 the urine. Lehmann, however, does not believe that they 
 exist preformed in the animal body. 
 
 (277.) The urine pigments have been carefully studied 
 both chemically, and in relation to diagnosis, but with little 
 profit in either direction. In addition to the remarks 
 in pp. 98, 99, it should be mentioned that Schunck* has 
 recently found indican (which seems to be identical with 
 Heller's f uroxanthin in the urine). This indican is the name 
 given to a gum-like mass obtained from the chromogen of 
 Indigoferous plants ; when boiled with acids it yields indigo- 
 blue, a peculiar description of sugar, and some other matters. 
 Schunck has obtained indigo-blue from the urine in so many 
 cases that we are entitled to place indican amongst the 
 normal constituents of the urine. Its quantity is however 
 extremely small, for by working for several weeks on the 
 urine of two persons Schunck only obtained one grain of 
 indigo-blue. The urine was examined for this substance in 
 forty different persons of different sexes and ages, and all of 
 whom were apparently in good health, and in every instance 
 except one it was detected. The amount seems to vary from 
 a comparatively tolerable quantity to a mere trace. Diet 
 had no apparent effect on its production ; and the state of 
 health and the appearance of the urine afford no indications 
 regarding the presence of an excess or deficiency of this 
 substance. 
 
 The urine of the horse and cow gave comparatively large 
 quantities of indigo-blue, especially that of the horse. 
 
 * Memoirs of the Literary and Philosophical Society of Manchester, 1857, 
 Vol. xiv. p. 239. 
 
 t See the foot-note to p. 98, in which it may be mentioned that there is a 
 misprint of Scherer for Sicherer. 
 
THE URINE. 311 
 
 The following are the general steps to be adopted in the 
 search for this substance. 
 
 The urine having been mixed with basic acetate of lead 
 until no more precipitate is produced, is filtered, and sulphuric 
 acid is then added to it on the filter. After the precipitate has 
 been washed with water the liquid is mixed with an excess of 
 ammonia, which gives more or less of a white or yellowish- 
 white precipitate. This precipitate is collected on a filter, 
 slightly washed with water, and then treated with dilute 
 sulphuric or muriatic acid in the cold. After the whole of 
 the oxide of lead has combined with the acid employed the 
 liquid is filtered. When there is much of the indigo-pro- 
 ducing body present the filter acquires a blue tinge ; small 
 particles of blue pigment are seen dotting the surface of the 
 sulphate or chloride of lead, and the surface of the liquid, 
 which is of a brownish-purple colour, in a very short time 
 becomes covered with a thin pellicle, which is blue by trans- 
 mitted and copper-coloured by reflected light, particles of 
 the same blue substance being at the same time found 
 attached to the sides of the vessel. When there is less of 
 the indigo-producing body present, this pellicle only appears 
 after some time, sometimes not till the next day. After 
 twenty-four hours, however, the action of the acid is always 
 completed, so that if no indigo-blue then appears or can be 
 detected on examination of the deposit the total absence 
 of the indigo-producing body may be inferred. 
 
 Mr. Schunck, from whose memoir the above method is taken, 
 believes that " the occurrence of the indigo-producing body 
 as an excretion is due to a disproportion between the oxygen 
 absorbed by the system and the matter to be acted on by it, 
 which again may be caused either by an excessive waste of 
 the tissues or by an obstruction of the organs conveying 
 oxygen, as the lungs and skin, or, as is probably the case in 
 the majority of instances, by an excess of food being taken over 
 and above the requirements of the system." As regards the 
 
 x 4 
 
312 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 constitution of this body, he thinks there can be no doubt that 
 it contains the elements of indigo-blue and sugar, and that 
 by oxidation within the system it is converted into the ordi- 
 nary extractive matter of the urine, which contains, as he has 
 ascertained, the elements of sugar and of the black substance 
 which is formed by the action of strong acids on urine, and 
 which may be considered as a product of the oxidation of 
 indigo-blue. He thinks it probable that the indigo-producing 
 body will be found, as regards its formation and composition, 
 to occupy a place between the substance of the tissues and 
 the ordinary extractive matter of urine. The formation of a 
 substance containing the elements of indigo-blue in the 
 animal system is a fact which may lead to important conclu- 
 sions regarding the chemical composition of the complex 
 bodies of which the blood and tissues consist. 
 
 Little or nothing is known regarding the chemical com- 
 position of the morbid colouring matters of the urine. 
 
 (278.) In considering the mineral constituents of the urine 
 we shall commence with the one which forms the greater part 
 of the bulk of the ash, namely, the chloride of sodium. 
 
 The relations of this salt to the urine have been very 
 thoroughly investigated by numerous observers.* Hegar, in 
 1852, published a series of observations on the subject. 
 Experimenting upon eight students he found that the daily 
 
 * The following table gives the results of the most trustworthy observations 
 on this subject. 
 
 Hegar (eight sets of observations) 
 Buchheim (six ) 
 
 Wagner (six ) 
 
 Kaupp. ..... 
 
 Do 
 
 Genth ...... 
 
 Do. . 
 
 Jul. Lehmann ..... 
 
 Bischoff (mean of forty days) . t ;*_ 
 
 These figures show how much the quantity daily excreted of chloride of 
 sodium may vary. They yield an average of 14-5 grammes. 
 
 Chloride of sodium 
 in twenty-four hours. 
 
 17*500 grammes 
 
 11-300 
 
 11-309 
 
 14993 
 
 17-046 
 
 12-834 
 18-507 
 
 9-614 
 14-790 
 
THE URINE. 313 
 
 average of chlorine varied in these individuals from 7-4 to 
 13*9 grammes, the general daily average being thus 10*46 
 grammes, which corresponds to 17 -5 grammes of chloride of 
 sodium. Vogel * considers this average too high, and regards 
 from 10 to 13 grammes, or from 150 to 200 grains, of 
 chloride of sodium as the normal average for an adult male, 
 the quantities being smaller for women and children. 
 
 The influence of age and sex is exhibited in the following 
 tabular view of Bischoffs observations on this subject. 
 
 Urine. Chloride of Sodium. 
 
 A man aged 45 years, weighing 238lbs. 53 fluid oz. 14-79 grammes. 
 A woman aged 43 198 33 9'13 
 
 A girl aged 18 146,, 25 7'46 
 
 A youth aged 16 107,, 26 8'80 
 
 After prolonged fasting, or after the use of food deficient in 
 chlorides, there is a diminished excretion of this salt. Wund 
 found that on totally abstaining from salt for five consecutive 
 days the quantities of chlorine which he excreted daily (and 
 of course it is an accurate measure of the chlorides) were 7-2, 
 3*6, 2*4, 1*4, and 1*1 grammes respectively. Falck, on con- 
 trasting the quantities of chlorine in the urinary chlorides 
 during diets consisting of non-salted and of salted food, found 
 that in the former case the chlorine was represented by 2*6, 
 1-7, and 0*9 grammes, while in the latter case the numbers 
 were 6*1, 7*9, and 10*3 grammes. Kaupp f has instituted a 
 very careful series of comparative experiments regarding the 
 amounts of ingested and excreted salt. They stand in a direct 
 
 * Die Semiotik des menschlichen Urines, p. 326; (being the second part of 
 Neubauer u. Vogel's Anleitung zur qual. u. quant. Analyse des Harns. 3rd 
 ed. 1858.) 
 
 f The following are some of Kaupp's mean numbers. 
 
 On taking daily 33 '6 grammes of salt he excreted 2 7 '3 grammes by the urine. 
 287 24-1 
 
 23-9 
 
 19-0 
 
 14-2 
 
 9'3 
 
 1-5 
 
 17-7 
 17-0 
 13-6 
 10-1 
 3'8 
 
314 PHYSIOLOGICAL CHEMISTRY. 
 
 ratio to one another, but the amount of the latter never 
 reaches that of the former, unless the amount of salt taken is 
 small. Similar experiments leading to similar results have 
 been made by Wagner and Buchheim. Wagner shows by 
 analysis that the missing chlorides are not contained in the 
 faeces ; they must therefore be mainly carried off in the sweat. 
 From experiments made by Hegar, Kaupp and others, it 
 appears that the excretion of chlorine reaches its maximum 
 in the afternoon and its minimum during the night, rising 
 again in the morning. The excretion of chlorine is increased 
 by bodily exercise, by sleeplessness, and by mental activity 
 (Hegar, Kaupp) ; by copious water-drinking (Grenth, Bischoff) 
 and by the free administration of liquor potassse (Parkes). 
 Tea, coffee, alcohol, and tobacco- smoking cause a diminution 
 in the excretion of the chlorides, doubtless by checking the 
 general metamorphosis of the tissues (J. Lehmann, Bocker, 
 Hammond).* 
 
 The amount of the excretion of chlorine (or of chloride of 
 sodium) is very much influenced by certain conditions of 
 disease. 
 
 Vogel concludes, from a very large number of observations, 
 that in all acute febrile diseases the excretion of chlorine by 
 the urine rapidly diminishes, and often attains a minimum 
 not exceeding the hundredth part of the normal quantity. 
 With incipient improvement we have an augmentation, and 
 as convalescence advances the chlorine reaches or even ex- 
 ceeds its normal quantity, f 
 
 * I gladly avail myself of this opportunity to express my opinion of the 
 great value of Dr. Hammond's physiologico-chemical researches, and at the 
 same time to thank him for his courtesy in transmitting to me copies of his 
 memoirs. 
 
 f The following cases are extracted from Vogel's work. It must be recol- 
 lected that Vogel regards the normal daily excretion of chlorine to range 
 from six to eight grammes. 
 
 (1) A man with severe pleuropneumonia. On the third day, the chlorine 
 had fallen to 0-6, on the fourth day to -3, and on the following day to almost 0. 
 It then steadily rose to 0'4, 1-8, 2'6, 5'5, and 9 grammes on successive days. 
 
THE URINE. 315 
 
 The diminution of the chlorine may be referred to several 
 causes. (1.) It is doubtless considerably due to the loss of 
 appetite, and to the comparatively saltless food taken by 
 patients with acute diseases. (2.) Chlorides are often, in 
 these cases, separated from the blood in other ways, as, for 
 instance, by watery diarrhoea or by serous effusions ; thus 
 Beale found that, while in the stage of hepatisation of 
 pneumonia the urine contained mere traces of salt, the sputa 
 and pulmonary tissue contained it abundantly. (3.) It is 
 possible that in these diseases the secreting activity of the 
 kidney, in relation to this, as well as to some other urinary 
 constituents, may be diminished. 
 
 From the preceding remarks it is obvious that we have 
 possession, in the amount of the excreted chlorine, of an im- 
 portant diagnostic (or rather prognostic) indication, which 
 may be thus laid down : 
 
 In all acute diseases a persistent diminution of the chlorine 
 indicates an increasing intensity of the disease, while a per- 
 sistent augmentation of the chlorine indicates a diminished 
 morbid action. If the daily chlorine is less than 0-5 of a 
 gramme, there is probably intense morbid action, accompanied 
 with anorexia and either watery diarrhoea or profuse serous 
 exudation. In cases of recovery, when the chlorine returns 
 to the urine, we can judge by its quantity regarding the im- 
 proved state of the patient. 
 
 In chronic diseases the daily amount of the excreted 
 chlorine forms a tolerably certain measure of the digestive 
 
 (2) A man with typhus. The chlorine rapidly sunk to a minimum, and 
 for several days was almost 0. With convalescence it gradually but irregu- 
 gularly increased, till it reached the normal quantity. 
 
 (3) A woman with acute articular rheumatism and pericarditis. It fell during 
 the height of the disease to 1, and gradually rose during convalescence to 6*3 
 grammes. 
 
 (4) A young man with severe febrile bronchial catarrh. It rapidly fell to 
 0-8, and then in the Course of a few days rose to 10'6 grammes. 
 
 (5) An old man similarly afflicted. It fell to 1-1, and during convalescence, 
 when food was freely taken, rose to 20-5 grammes. 
 
316 PHYSIOLOGICAL CHEMISTRY. 
 
 powers of the patient. When from six to ten grammes are 
 excreted, we infer that the digestion is good; when a smaller 
 quantity than five grammes is excreted we infer that it is 
 impaired, unless chlorine is being simultaneously carried off 
 by watery stools, or the prescribed diet should be deficient in 
 chlorides. A very increased excretion of chlorine is a favour- 
 able sign in cases of dropsy. 
 
 In the preceding remarks we have sometimes used the 
 term chlorides, but in reality nearly all the chlorine contained 
 in the urine occurs there as chloride of sodium. 
 
 Sulphates are always present in the urine, but apparently 
 (as may be seen by the results recorded in the footnote) * in 
 very varying quantity. Lehmann (in his " Handbuch ") 
 states that an adult man secretes 'daily 2*1 grammes or about 
 32-4 grains of sulphuric acid. 
 
 The urine of young children contains a comparative excess 
 of sulphates (Lehmann). 
 
 The nature of the food and the period of digestion consider- 
 ably affect the amount of the excretion of sulphates. During 
 a twelve days' persistence on a strictly animal diet, Lehmann 
 excreted as the mean amount 10-399 grammes of sulphates 
 (not sulphuric acid), while the corresponding mean amount, 
 during a purely vegetable diet, was only 5*846 grammes ; and 
 similarly, Clare, during a purely animal diet of three days' 
 duration, excreted on an average 3-697 grammes of sulphuric 
 
 * The following are the most trustworthy results regarding the daily excre- 
 tion of sulphuric acid, in the form of soluble sulphates. 
 
 Sulphuric acid. 
 
 Lehmann (mean of experiments on himself) . 3 '9 34 grammes. 
 
 Gruner (mean of experiments on 7 persons) . 1-904 
 
 Buchheim (mean of 12 experiments on himself) . 1-741 
 Wagner (mean of 10 experiments on himself) . 2-105 
 Neubauer (mean of 17 experiments on himself) . 2-480 
 Do. (mean of 22 days' experiments on another man) 2-270 
 Clare (mean of 14 experiments on himself) . 2-280 
 
 If we omit Lehmann's result, which is obviously abnormally high, we obtain 
 2-13 grammes as the mean daily quantity of excreted sulphuric acid. 
 
THE URINE. 317 
 
 acid, and during a purely vegetable diet 1-559 grammes. 
 Grruner found that during perfect abstinence the sulphuric 
 acid of the first twenty-four hours was not diminished, but it 
 is very improbable that this should be generally the case. 
 According to Dr. Bence Jones there is a temporary augmen- 
 tation of the sulphuric acid shortly after every meal. Grruner 
 and Beneke found that the curve representing the secretion 
 of this acid rises during the afternoon hours (the period of 
 digestion), sinks during the night, and reaches its minimum 
 in the forenoon. According to Dr. Parkes, the sulphuric 
 acid in the urine goes on rising for three hours after a meal, 
 and continues increasing for three hours more. Copious water- 
 drinking increases the daily amount of the excreted sulphates *, 
 so also do strong bodily exercise, and great mental excite- 
 ment. The sulphates of the alkalies when taken in con- 
 siderable doses, are entirely eliminated in from eighteen to 
 twenty-four hours, unless when a portion of them passes off 
 with the solid excrements ; and after the administration of 
 large doses of free sulphuric acid and of sulphur, as also after 
 the ingestion of golden sulphide of antimony in five-grain 
 doses, four times daily, the excretion of sulphuric acid is 
 temporarily augmented. 
 
 From the above remarks it is obvious that there are 
 various causes modifying the amount of the excretion of sul- 
 phuric acid. 
 
 1. The excretion is augmented by the administration of 
 sulphuric acid, sulphates, and other sulphur compounds whose 
 sulphur becomes oxidised in the body into sulphuric acid. 
 
 * Genth (whose investigations on the influence of water-drinking on the 
 metamorphosis of the tissues are deserving of careful study) found that while 
 living on a strictly regulated diet he discharged daily 1252 c. c. of urine con- 
 taining 2 -552 grammes of sulphuric acid ; when drinking additionally 1000 c. c. 
 of water the urine rose to 2325 c. c. and the sulphuric acid to 2751 grammes; 
 when drinking 2000 c. c. of water the urine amounted to 3251 c. c. and the 
 sulphuric acid to 2 985, and when drinking 4000 c. c. of water, the urine rose 
 to 5075 c. c. and the sulphuric acid to 3-274 grammes. 
 
318 PHYSIOLOGICAL CHEMISTRY. 
 
 2. During an abundant animal diet the sulphur con- 
 tained in the protein-bodies of the flesh is probably liberated 
 (or is in a comparatively loose state of combination) as the 
 digestive process advances, and is gradually oxidised in the 
 blood into sulphuric acid. 
 
 3. Independently of the introduction of sulphur into the 
 system from without, we may have an augmentation of the 
 sulphuric acid from any internal cause that tends to any 
 great extent to augment the metamorphosis of the tissues. 
 
 It is unnecessary to advert to the effect of disease upon the 
 excretion of the sulphates, as Vogel, who has made a large 
 number of observations on this point, declares that he has 
 .not been able to arrive at any definite result. It is true 
 that in most febrile diseases we have a very considerable di- 
 minution of the sulphates, but this result is doubtless due 
 solely to the ordinary character of the diet in these cases. 
 
 Phosphoric acid is another of the normal constituents of 
 the urine. It occurs partly as the acid phosphate of soda 
 (or, according to Rose, of potash, see p. 135), to which the 
 urine mainly owes its acid reaction, and partly in combination 
 with lime and magnesia. 
 
 An adult man excretes daily from 3-2 to 3 '8 grammes, or 
 from 50 to 60 grains of phosphoric acid.* The normal range 
 is however a wide one, Breed and Winter finding as their 
 maximum in two cases 6-45, and 3*18 grammes, while 
 Neubauer and Mosler found as their minimum in two cases 
 1-21 and 1*08 grammes; and even in the same person the 
 quantities may be very different on different days ; thus a 
 
 * The following include the most trustworthy results regarding the excre- 
 tion of phosphoric acid : 
 
 Breed (mean of 4 cases) . . 3*7 grammes. 
 
 Winter, in one case . . . 37 
 
 in a second case . . 4 '2 ' 
 
 in a third case ... 5*2 
 
 Mosler in one case . . . 2-4 
 
 in the same case at a subsequent time 3'7 
 
THE URINE. 319 
 
 man who one day excreted 4*88 on another day excreted only 
 2 '44 grammes (Neubauer), and many similar illustrations 
 might be given. According to Hegar, Gruner and Winter, 
 an adult man excretes daily an average of 0*064 of phosphoric 
 acid for 1000 parts of bodily weight. Winter, Mosler and 
 Vogel agree in the statement that the diurnal excretion of 
 phosphoric acid presents a regular law. The quantity be- 
 gins to increase in the afternoon (shortly after the principal 
 meal), it reaches its maximum in the evening, falls during 
 the night, and attains its minimum in the forenoon. 
 
 The quantity of phosphoric acid in the daily urine is in- 
 creased by the ingestion of phosphoric acid or of soluble 
 phosphates into the organism; thus Aubert* found that 
 while his normal daily excretion of this acid was 2*8 grammes, 
 it rose after he had swallowed 31 grammes of phosphate of 
 soda to 4*1 grammes. 
 
 The amount of the excreted phosphoric acid is much 
 affected by the food ; being increased by those foods which 
 contain phosphoric acid or phosphorus-compounds, which by 
 oxygenation in the blood become converted into that acid, and 
 diminishing during prolonged abstinence, without, however, 
 like the chloride of sodium, finally altogether disappearing, f 
 It is more abundant during an animal than during a vegetable 
 diet. (In Professor Haughton's experiments, it was found that 
 the relative daily quantities of phosphoric acid in flesh-fed 
 and vegetarian subjects were 37-1 and 26-7 grains respec- 
 tively.) 
 
 Neubauer, in one case . . 3-1 grammes. 
 
 in another case . . 1'6 
 
 Genth (mean of two observations) . 3-4 
 
 Kaupp (mean of two observations) . 3-4 
 
 The above numbers give a general mean of 3-4 grammes. 
 
 * Zeitsch f. rat. Med. 1852. New Ser. vol. ii. p. 225. 
 
 f Schmidt observed that after prolonged abstinence, a cat excreted daily 
 only one- third of the normal quantity of phosphoric acid, Mosler has made 
 similar observations on man, 
 
320 PHYSIOLOGICAL CHEMISTRY. 
 
 Any cause which increases the rapidity with which the 
 metamorphosis of the tissues proceed, augments the excretion 
 of this acid ; thus, for instance, after strong bodily exercise or 
 prolonged mental excitement, or after the copious ingestion of 
 water (or watery fluids, such as beer, &c.) we have an aug- 
 mentation of the phosphoric acid, while after the use of sub- 
 stances which check the rapidity of disintegration, such 
 as coffee and alcohol, we have a diminution of this con- 
 stituent. 
 
 The changes impressed upon the excretion of this acid in 
 disease have been most laboriously studied by Vogel, who 
 has made more than 1000 analyses in reference to this point. 
 His results are, however, not very striking. Even in severe 
 febrile affections there is no very material diminution of the 
 phosphoric acid, probably not more than is due to the altered 
 diet, and again occasionally, even at the very height of an 
 acute disease (pneumonia, for instance), the phosphoric acid 
 may exceed the normal quantity. 
 
 We have hitherto been speaking of the collective phos- 
 phoric acid that is daily excreted, that, namely, which is 
 combined with soda, together with that comparatively small 
 portion which is combined with the earths. These earthy 
 phosphates the phosphates of lime and magnesia now 
 claim some independent notice. 
 
 Earthy The earthy phosphates excreted daily by an adult man, 
 
 phates. amount on an average to 1 gramme.* The quantity, however, 
 
 * The following are the most trustworthy of the determinations of the daily 
 quantity of earthy phosphates excreted by an adult male. 
 
 Lehmann . . . I 09 grammes. 
 
 Beneke . . . .1'20 
 
 Bocker . .' 1-48 
 
 Neubauer has made an extended series of observations on this subject, upon 
 four healthy young men with the following results : 
 
 1. In the normal state, a young man living on mixed food excretes on an 
 average (taking fifty-two observations) from 0-944 to 1*012 grammes. The 
 ordinary maximum ranged from 1-138 to 1-263 grammes, and on one occasion 
 
THE URINE. 321 
 
 is liable to considerable variation, and depends to a great 
 extent upon the nature of the food ; thus, for instance, Leh- 
 mann found, in experiments upon the effect of different kinds 
 of diet upon his own urine, that while living on his ordinary 
 mixed food, he excreted 1*09, and while living on purely 
 animal food 3-56 grammes. The excess of phosphoric acid 
 which occurs during an animal diet, seems, however, accord- 
 ing to Professor Haughton to be distributed in a fixed ratio 
 between the soda and the earths, for he finds that the phos- 
 phoric acid in combination with the former, is to that in 
 combination with the latter as 4*1 both in well-fed men and 
 in vegetarians. In the urine of young children and of preg- 
 nant women, there is often a great diminution of the phos- 
 phate of lime ; indeed, after the sixth month of pregnanc}^, 
 we often fail to detect any indication of its presence. 
 
 The determination of the amount of the earthy phosphates 
 in cases of disease is of comparatively little value, because so 
 very large a proportion of them is carried off by the faeces, that 
 the remaining urinary portion affords no trustworthy indica- 
 tion of the rapidity with which metamorphic disintegration 
 is going on. 
 
 Iron is usually, although not invariably found in very Iron. 
 minute quantities in the urine of perfectly healthy persons. 
 After the medicinal use of ferruginous preparations, iron may 
 sometimes be detected in the fresh urine by the application 
 
 1-554 grammes were excreted. The ordinary minimum was 0-8 ; once only 
 0'328 of a gramme was excreted. 
 
 2. The phosphate of lime usually ranged from 0*31 to 0-37 of a gramme ; 
 the largest and the smallest quantities observed being 0-616 and 0-15 of a 
 gramme. 
 
 3. The average quantity of the phosphate of magnesia was 0'64 of a gramme ; 
 the observed maximum and minimum were 0-938 and 0*178 of a gramme. 
 
 4. About three equivalents of phosphate of magnesia, 2MgO.PO 5 , are ex- 
 creted for every equivalent of phosphate of lime, 3CaO.P0 5 ; and in 100 parts 
 of the collective phosphates there are on an average 67 of phosphate of mag- 
 nesia and 33g of phosphate of lime ; a result which is almost identical with that 
 obtained some years previously by Kletzinsky. 
 
322 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Silica and 
 Eluorine. 
 
 Ammonia. 
 
 Gases. 
 
 Water. 
 
 of the ordinary tests ; generally, however, it is only in the ash 
 that it can be detected. It is a constituent of the urohsematin 
 described by Harley as the essential normal urine-pigment 
 (see p. 98). 
 
 Silica, in minute traces, has been detected, in the ash of 
 healthy urine by Berzelius and by Fleitmann; and very 
 minute traces of fluorine have been found in it by Gr. Wilson 
 and by Mckles. 
 
 (279.) Whether ammonia is a normal constituent of 
 healthy urine, or whether it is merely a product of the de- 
 composition of some of the nitrogenous ingredients of the 
 urine is still a disputed question. Liebig, Scherer, and Leh- 
 mann (perhaps the three highest authorities in reference to 
 animal chemistry) deny its presence as a normal constituent, 
 while on the opposite side may be mentioned the names of 
 Heintz, Bocker, Boussingault, De Vry, and Neubauer. The 
 experiments of the last-named chemist, which present no 
 apparent fallacy, show that a healthy adult male excretes 
 daily an average of 0-7234 of a gramme of ammonia, corre- 
 sponding to 2 '2 7 83 grammes of hydrochlorate of ammonia, 
 the form in which, if present, it probably exists in the urine. 
 Lehmann grants that ammonia may occasionally be found in 
 fresh urine, but in these cases he is of opinion that it is formed 
 in the bladder from some change in the extractive matter ; 
 and this explanation would give a clue to the interpretation 
 of a result obtained by Neubauer, namely, that very copious 
 water-drinking occasioned an excess of ammonia, for it is well 
 known that watery urine decomposes more rapidly than con- 
 centrated urine. We shall in a future page refer to the 
 presence of ammonia in certain forms of morbid urine, in 
 which alkaline fermentation has taken place. 
 
 (280.) Gases, especially carbonic acid and a little nitrogen, 
 exist in the urine in a state of solution. 
 
 (281.) The quantity of water excreted daily by the kidneys 
 is so variable even under purely physiological conditions, that 
 
THE URINE. 323 
 
 it is difficult for us to attempt to fix an average.* It may be 
 more or less modified by any of the following causes ; the 
 quantity of water that has been drunk, or that has been ab- 
 sorbed in bathing ; the character of the excrements, and the 
 degree of cutaneous excretion, which again is dependent on 
 the temperature and moistness of the atmosphere, upon bodily 
 exercise, &c. 
 
 From the investigations of Falck, Grenth, and others, it Action of 
 appears that after the use of large quantities of water, not t c h r e 
 only is there more water, but a larger amount of solids, sepa- urinary 
 rated by the kidneys. The excess of water is removed from 
 the system in about six hours. The injection of water into 
 the circulation through a vein does not seem to induce a cor- 
 responding excess of urine. Shortly after a meal the urine 
 is found to present both an absolute and relative deficiency of 
 water, and an excess of solid constituents. 
 
 (282.) The acid reaction of the urine mainly depends upon The free 
 the acid phosphates of the alkalies and earths which it con- 
 tains, but partly also, in some cases, on the presence of free 
 hippuric or lactic acid. To determine the acidity we take 
 a solution of oxalic acid of known strength, and ascertain 
 the relative quantities of a solution (of definite strength) of 
 caustic soda, which are required to perfectly neutralise equal 
 
 * The following table, drawn up from memoirs by Scherer and Rummel, shows 
 in certain cases the ratio of the excreted water to 1000 parts of bodily weight. 
 A child aged 2 years, 64-33 parts of water for 1000 parts of weight. 
 
 3 44-85 
 
 4 52-50 
 
 5 40-40 
 
 7 46-29 , 
 
 A man aged 18 42-00 
 
 22 33-17 
 
 31 30-40 
 
 38 24-12 
 
 65 41-30 
 
 The last five of these numbers give us for adults a mean of about 34-2 of 
 water for 1000 parts of weight. According to this estimate a man weighing 
 10 stone excretes daily 4-8 \bs. of water. 
 
 Y 2 
 
324 PHYSIOLOGICAL CHEMISTEY. 
 
 volumes of the urine and the oxalic-acid solution. Determined 
 in this way, the total quantity of free acid in the daily urine 
 of a healthy man corresponds in neutralising power to about 
 2*3 grammes of oxalic acid, the range being from 2 to 4 
 grammes. It appears from the researches of Winter and 
 Vogel, that in the forenoon the acidity is at its minimum; that 
 during the period of digestion of the principal meal it attains 
 its average ; and that in the night it reaches its maximum.* 
 
 * There has been so much discussion and difference of opinion regarding the 
 variations in the acidity of the urine, that it seems expedient to notice the 
 principal views that have been propounded on this subject. It was formerly 
 regarded as an unquestioned fact that the normal urine of man was always 
 acid ; but in 1849 Dr. Bence Jones (Phil. Trans.), published the view now gene- 
 rally entertained (with some limitation)' by physiologists, that the secretions of 
 the stomach and kidneys stand in an inverse relation to one another in regard to 
 their reaction ; that when the stomach is empty, the secretion on the surface of 
 its walls is neutral or faintly alkaline, while the urine is strongly acid, that 
 when the stomach contains acid gastric juice (namely, during stomachal diges- 
 tion), the urine is much less acid or even alkaline, and that, as this acid gastric 
 juice becomes reabsorbed and passes into the blood, the acidity of the urine is 
 restored. Although there is much truth in this view generally, it is not univer- 
 sally true, nor is it always that the urine becomes positively alkaline during 
 digestion. Beneke (Arch. d. Vereins f. wissens. Heilk. vol. i. p. 438) ex- 
 amined his own urine on twenty-three days, and could not discover any con- 
 nection between its acidity and the digestive process ; but states that in a large 
 number of observations on different healthy persons and patients, the urine 
 occasionally, but by no means constantly, exhibited a depressed acidity, or even 
 an alkaline reaction after a meal. Vogel ( Anleitung z. Analyse d. Harns.) found 
 that observations made by himself and by his students led to the result given in 
 the text, that the greatest quantity of acid secreted in an hour occurs during 
 the night. Dr. Seller (Edin. Monthly Journ. Jan. 1859) declares that Dr. Bence 
 Jones's law is not " generally applicable in Edinburgh." The latest results are 
 those of Dr. Roberts, of Manchester (Edin. Monthly Journal, March and 
 April, 1860), whose " experiments confirmed in the fullest manner the conclu- 
 sions of Dr. Bence Jones, that a meal, be it of animal, vegetable, or mixed 
 food, has a powerful and constant effect in lowering the acidity of the urine, 
 frequently even rendering it alkaline." ..." The effect of dinner," says Dr. 
 Roberts, " was not perceptible until the second hour after the meal. During 
 the next three hours (third, fourth, and fifth hours), the alkaline tide ran in its 
 greatest strength. On the third and fourth hours, the urine was always (with 
 two exceptions), found alkaline when the meal had been of mixed food or 
 animal diet. At the end of the sixth hour the tide had generally turned, and 
 the acid reaction been restored. . . The alkaline urine that was passed after 
 
THE URINE. 325 
 
 After the administration of caustic alkalies, their carbonates? 
 or their salts with organic acids, the acidity diminishes, and 
 we often have the urine positively alkaline ; while after the 
 administration of acids it is considerably increased. 
 
 From a large number of determinations of the acidity, 
 Vogel has arrived at the conclusion that in most diseases, 
 acute as well as chronic, it is diminished ; and it is scarcely 
 ever increased except when the mineral acids have been 
 medicinally administered in large doses. It must be recol- 
 lected that in febrile, and probably other affections, the acid 
 fermentation (see p. 296), ensues very rapidly, giving rise to a 
 large amount of free acid in the urine ; hence the acidity 
 should be determined very shortly after the emission. 
 
 The close connection between the acidity of the urine and 
 t\\Q nature of the food has been shown by Bernard and others. 
 In carnivorous animals the urine is naturally acid ; in herbi- 
 vorous, alkaline ; if, however, a carnivorous animal be fed 
 solely on vegetable food, or a herbivorous animal on a flesh 
 diet, the reverse is observed ; namely, the urine of the carni- 
 vorous animal is alkaline, and that of the herbivorous animal 
 acid. Moreover, in starving herbivorous animals (horses and 
 rabbits), it is found that after a few days their urine is acid, 
 
 food owed its reaction to a fixed alkali, and not to ammonia. It did not 
 effervesce with acids. It was rich in earthy and alkaline phosphates ; and on 
 these latter, in a basic state, depended apparently its alkaline reaction. As 
 might have been anticipated, the loss of acidity entailed the precipitation of 
 the earthy phosphates ; and the urine when passed was frequently turbid. . . 
 The odour of this alkaline urine resembled that of the fresh urine of the horse 
 It had lost the characteristic urinous odour, and exhaled a strong sweetish 
 aroma, so peculiar as to indicate with certainty the change of reaction without 
 the aid of test paper." Although Dr. Roberts's facts corroborate those of 
 Dr. Bence Jones, his explanation is somewhat different. He maintains that 
 the alkaline tide is concomitant with the absorption of the meal into the blood, 
 rather than with its digestion, and that the passage of the meal into the blood 
 affects the reaction of the urine by temporarily increasing the alkalinity of the 
 blood by the carbonates and basic alkaline phosphates of the food. One of the 
 strongest arguments in favour of th'is view is the fact, that when food devoid 
 of mineral constituents was used (such as sugar or honey), there was no 
 lowering of the acidity of the urine. 
 
 Y 3 
 
326 PHYSIOLOGICAL CHEMISTRY. 
 
 as might, indeed, be expected, for they are then living on 
 their own blood and tissues.* 
 
 Incidental (283.) We now proceed to the consideration of those sub- 
 entsf 11 stances which, if present in the urine, must be regarded 
 merely as incidental constituents. Putting out of considera- 
 tion all articles of true food, we may assume that generally 
 only those substances are likely to pass into the urine which 
 are readily soluble in water, which do not form insoluble 
 compounds with any of the tissues of the body, and which 
 are not readily oxidised or decomposed. Thus, the nitrates, 
 chlorates, borates, carbonates, and silicates of the alkalies, 
 and the chlorides, bromides, and iodides of potassium and 
 sodium re-appear unchanged ii\ the urine ; while other com- 
 pounds, as, for instance, the sulphide of potassium, become 
 oxidised, and are eliminated as sulphate of potash, &c.' Many 
 substances which form insoluble compounds with the albu- 
 minates, as for instance, all the metallic salts, only reappear 
 in the urine when they have been administered in very 
 large quantities. 
 
 Various organic bodies appear to experience in their organism 
 the same changes which they may be made to undergo in the 
 laboratory, by means of oxidising agents ; and in these cases 
 it is only the products of their oxidation that we can expect 
 to find in the urine : this, for example, is the case with 
 salicin. Others, again, are so perfectly oxidised as to leave 
 only carbonic acid and water as their final products ; hence, 
 although they may, in a disintegrated state, pass into the 
 urine, no trace of their existence can be recognised : as is the 
 case with mannite. When, however, very large quantities of 
 substances of this class are taken, a portion passes unchanged 
 into the urine ; for example, mannite has under these cir- 
 
 * Bernard, moreover, finds that by placing rabbits in an atmosphere of pure 
 oxygen, he can make them excrete for a- time an acid urine. He has like- 
 wise discovered the singular fact, that on injecting oil into their lungs, their 
 urine rapidly becomes acid. 
 
THE URINE. 327 
 
 cumstances been detected by Buchheim and Witte in the 
 urine. 
 
 Although as the general rule oxidation is the process to 
 which bodies are exposed in the organism, there are ex- 
 ceptional cases, in which a highly oxidised substance reap- 
 pears in the urine with a loss of a portion of its oxygen ; 
 thus, for instance, indigo-blue appears as reduced indigo ; 
 ferridcyanide of potassium (the red prussiate) as the ferrocya- 
 nide (the yellow prussiate), &c. 
 
 The sulphocyanide and ferrocyanide of potassium, the salts 
 of ammonia and baryta, and most of the organic acids pass 
 unchanged into the urine ; tannic acid is, however, converted 
 into gallic acid, and benzoic and cinnamic acids are changed 
 into hippuric acid.* Nitrobenzoic acid is converted into 
 nitrohippuric acid ; succinic acid does not reappear in the 
 urine. Uric acid is converted into urea, oxalic acid, carbonic 
 acid, and water. The neutral salts formed by the vegetable 
 acids with alkalies (tartrates, citrates, acetates, &c.) reappear 
 in the urine as corresponding carbonates, and consequently 
 impress upon the urine an alkaline reaction, which usually 
 manifests itself very shortly after their administration. 
 
 Oxalic, malic, tartaric, gallic, camphoric, anisic, cuminic, 
 picric, and salicylous acids have been found to pass unchanged 
 into the urine, although in far less quantity than that in 
 which they were administered. 
 
 Quinine and urea pass unchanged into the urine, while 
 aniline, theeine, theobromine, allantoine, alloxanthine, amyg- 
 
 * Kanke has shown that at a temperature considerably lower than that of 
 the human body, tannic acid has, by the catalytic action of yeast, been con- 
 verted into gallic acid, and other products. There is strong reason to believe 
 from the researches of Kiihne and Hallwachs, that benzoic acid is converted 
 into hippuric acid by combining with glycine in the liver. The combination 
 may possibly be expressed as follows : 
 
 1 eq. benzoic acid (C 14 H 6 O 4 ) + 1 eq. glycine (C 4 H 5 NO 4 ) = 1 eq. hippuric acid 
 (C 18 H 9 NO 6 ) + 2 eq. water (2HO). 
 Y 4 
 
328 PHYSIOLOGICAL CHEMISTRY. 
 
 dalin, asparagin, phlorrhidzin, and santonin*, are found to 
 yield no indications of their presence. Salicin, if taken in 
 large doses, partly reappears unchanged; in smaller doses it 
 reappears in the form of saligenin, and salicylous, salicylic, 
 and sometimes salicyluric acids. 
 
 Most pigments, and many odorous principles, pass un- 
 changed, or only slightly modified, into the urine. Wohler 
 found in the course of his experiments that the pigments of 
 indigo, madder, gamboge, rhubarb, logwood, red beet-root, 
 and of bilberries, passed into the urine ; while those of cochi- 
 neal, litmus, sap-green, and alkanna could not be detected. 
 To the above list of pigments passing into the urine, that of 
 senna should be added. Both rhubarb and senna communi- 
 cate a brown tint to the urine, not unlike that produced by 
 blood, but any error from this resemblance may be easily 
 avoided by the addition of a mineral acid, which produces a 
 light yellow colour in the two former, and a darker brown in 
 the latter case. 
 
 The odorous principles detected by Wohler were those of 
 valerian, garlic, asafcetida, castoreum^ saffron, and turpentine ; 
 he found no traces of camphor or musk. 
 
 (284.) The rapidity with which substances that have been 
 swallowed reappear in the urine, differs very much. As a 
 general rule, to which, however, there are a good many ex- 
 ceptions, the rapidity is proportional to the solubility of the 
 substance, and to its unchangeability in the system. Iodide 
 of potassium, in a case in which the anterior wall of the 
 bladder was absent, showed itself in the urine in four to ten 
 minutes ; usually it does not appear in less than three 
 
 * Phlorridzin in a non-nitrogenous compound closely resembling salicin, and 
 obtained from the bark of the root of the apple, pear, &c. ; santonin, is a 
 similar compound obtained from Artemisia contra. The statement in the text is 
 perhaps rather too strong, as if, after the administration of santonin, the urine 
 be made alkaline either within the system (as by the administration of citrate 
 or tartrate of potash) or externally (as by the addition of ammonia, &c.), it 
 assumes a beautiful red colour. 
 
THE URINE. 329 
 
 quarters of an hour, and may even be five hours before it 
 shows itself. After the administration of two or three drachms 
 of bicarbonate of potash, Lehmann observed that the urine 
 of the persons on whom he was experimenting became alka- 
 line in from half an hour to an hour ; while after the admini- 
 stration of half an ounce of lactate of soda (calculated as dry) 
 it became alkaline in thirteen minutes. Erichson found 
 that after administering two scruples of ferrocyanide of potas- 
 sium to a man in whom the anterior wall of the bladder 
 was absent, the salt appeared in the urine in two minutes. 
 He likewise observed that this and other salts passed 
 through the system less rapidly when taken shortly after a 
 meal. 
 
 Moreover, the time required for the complete excretion of 
 a substance that passes into the urine varies considerably. 
 Lehmann found that after a dose of two drachms of acetate 
 of soda the alkaline reaction of the urine completely disap- 
 peared in ten hours, while after three drachms of bicarbonate 
 of soda the urine remained alkaline for three days. In some 
 persons a dose of ten grains of iodide of potassium leaves no 
 trace in the urine after twenty-four hours ; in other persons 
 it may be detected after a space of three days. 
 
 Substances which form insoluble compounds with the 
 albuminates are very slowly and gradually eliminated by the 
 urine. Metallic preparations (as of arsenic, lead, copper, 
 mercury, antimony, &c.) may be detected long after their 
 administration in the liver and other parts. We are indebted 
 to Melsens and Hannon for the discovery of the important 
 practical fact, that the elimination of lead and mercury by the 
 kidneys may be much accelerated by the administration of 
 iodide of potassium, which forms in the system soluble iodides 
 of those metals. 
 
 (285.) The incidental constituents of which we have been Abnormal 
 treating have been introduced into the system from without. ents . 
 We have next to notice those abnormal substances which occur 
 
330 PHYSIOLOGICAL CHEMISTRY. 
 
 in the urine in certain forms of disease, and which originate 
 within the body itself. 
 
 Albumen* is the most important of these abnormal con- 
 stituents. As its presence may indicate the existence of an 
 intractable disease, while on the other hand it may be of 
 comparatively trifling importance, we must investigate the 
 different conditions which may cause its appearance in the 
 urine. 
 
 1. Albuminous urine may be due to some mere local affec- 
 tion of a limited portion of the uropoietic tract. Thus any 
 lesion occasioning the presence of blood or pus in the urine 
 renders it albuminous ; in cases of this nature a sediment will 
 occur, and its microscopic examination will reveal the nature 
 of the foreign admixture. The reflux of spermatic or prostatic 
 fluid into the bladder may possibly have a similar effect. 
 
 2. The urine may become albuminous in certain forms of 
 renal irritation and congestion, in which the action of the 
 capillaries is so far altered as to admit of the permeation of 
 albumen through their walls. Thus we sometimes find the 
 urine albuminous after the administration of cantharides and 
 other highly stimulating diuretics. A similar condition may 
 also be induced mechanically by tying the renal veins, or the 
 aorta just beyond the point at which the renal arteries are 
 given off; by the injection of large quantities of water into the 
 blood ; and in short by anything that increases the pressure 
 of the blood in the capillaries of the kidneys. In this way 
 certain diseases of the liver, heart, and lungs may cause albu- 
 minous urine. 
 
 3. Independently of any renal affections, it is more than 
 probable that certain conditions of the blood, due to altered 
 metamorphosis of the tissues, may occasion the escape of 
 albumen through the capillary walls into the urine. Thus, 
 
 * The remarks upon the presence of albumen are taken almost verbatim 
 from Vogel's Semiotik des menschlichen Urines : a work from which I have 
 borrowed freely in this chapter. 
 
THE URINE. 331 
 
 for instance, when the blood-serum is very poor in albumen 
 and rich in water we very frequently find some of the albu- 
 men, escaping into the urine. Again, it has been ascertained 
 (in experiments on animals), that the injection of albu- 
 minous solutions into the blood often (but not invariably) 
 renders the urine albuminous, and the discrepancy in the 
 results has led to the hypothesis that some modifications of 
 albumen may pass more readily through the walls of the renal 
 capillaries than others ; and that such modifications can be 
 produced in the albumen of the blood by certain forms of 
 disease. Whether these modified conditions of the blood are 
 accompanied by a perceptible change in the tissue of the 
 kidneys (hypersemia, and distention of the capillaries) is uncer- 
 tain ; but even if it occur, it is only of a temporary character ; 
 and hence, from the mere existence of albuminuria, unsup- 
 ported by other evidence, we must not infer the necessary 
 existence of those organic changes in the kidney which are 
 known as Bright's disease. Putting out of consideration 
 other symptoms, we cannot conclude from the urine that 
 Bright's disease is present, unless (1) albumen has been long 
 and constantly present, and (2) unless fibrinous casts are 
 simultaneously present in the urine (see pp. 372-4). 
 
 The only diseases in which albumen is almost invariably 
 present in the urine, are Bright's disease and the other 
 diseases with which uraemia is associated, such as the dropsy 
 occurring after scarlatina, cholera, and partial suppression of 
 urine. There are, on the other hand, few acute diseases 
 in which it is not sometimes found.* 
 
 Albuminous urine is occasionally observed in persons who 
 are apparently quite healthy. 
 
 * Finger (of Prague), examined the urine of 600 patients for albumen. In 
 88 cases of typhus it was found 29 times, in 46 of puerperal fever, 32 times ; in 
 33 of pneumonia, 15 times ; it was of more rare occurrence in intermittent 
 fever, pleurisy, peritonitis, and mucous diarrhoea, and was not found once in 
 18 cases of acute rheumatism. 
 
332 PHYSIOLOGICAL CHEMISTRY. 
 
 Fibrin. Fibrin is stated occasionally to occur, independently ot 
 
 blood-corpuscles, in the urine. In these cases the inter- 
 cellular fluid of the blood must permeate the walls of the- 
 capillaries. The fibrin seems to remain fluid till after the 
 urine is discharged, when it separates in clots, granules, or 
 stringy masses. The chylous or milky urine, described by 
 Rayer, Bence Jones, and others, contains fibrin in addition 
 to other abnormal constituents. 
 
 The occurrence of fibrinous casts or tubes in the urine 
 will be noticed in the remarks on urinary sediments. 
 
 Casein. Casein has never been detected with certainty in the urine. 
 
 Other Protein-bodies, differing from albumen, fibrin, and casein, 
 
 bodies"" occasionally occur in the urine. Through the kindness of my 
 friend, the late Dr. Macintyre, I had the opportunity of 
 examining a very remarkable variety of urine passed by a 
 patient with mollities ossium. It contained a protein-body, 
 as was evidenced by the reactions of acetic acid, ferrocyanide 
 of potassium, and strong hydrochloric acid ; but this body 
 differed from the ordinary substaaces of this class in being 
 soluble in boiling water, and in the nitric-acid deposit 
 being soluble on warming, and being again thrown down on 
 cooling.* 
 
 Fat. Fat does not occur, except in the slightest trace, in normal 
 
 human urine. There are, however, some forms of disease in 
 which it occurs in appreciable quantity.; as, for example (and 
 especially), in Bright's disease f, in rhachitis, hepatitis, 
 cirrhosis of the liver, and chronic insanity. According to 
 Lehmann, fat-globules are often found in the urine of persons 
 who are becoming rapidly emaciated from any disease. The 
 same observer also notices that in the milky or chylous urine, 
 previously mentioned, the turbidity is not mainly due to 
 
 * The chemical characters of this substance were described by Dr. Bence 
 Jones in the Philosophical Transactions for 1847. 
 
 f Kletzinsky found the following quantities of fat in 1000 parts of urine in 
 cases of Bright's disease, 0'24, 0'26, 0'28, 0*35, 0-37, 0'48, 1'27. Beale in one 
 case found a much larger quantity. 
 
THE URINE. 333 
 
 fat-globules (as was generally believed), but to pus-corpuscles, 
 which, however, contain a considerable amount of fat. 
 Cholesterin has been detected by Beale* on several occasions 
 in the urine in Bright's disease. 
 
 While there can be no doubt that fatty degeneration of the 
 kidneys is the most common cause of an excess of fat in the 
 urine, it is not improbable that wherever there is, from any 
 cause, an excess of fat in the blood, a portion may be elimi- 
 nated by the kidneys. 
 
 It has been already stated in page 89 that sugar does not Sugar, 
 occur in healthy urine, and we have there briefly noticed 
 the conditions under which it appears in that fluid, f 
 
 * Archives of Medicine, vol. i. p. 8. A notice of the only other cases on 
 record may be found in my Translation of Simon's Animal Chemistry, vol. ii. pp. 
 313 and 333. 
 
 f Briicke has recently attempted to prove that sugar is a normal constituent 
 of human urine. The following is his method of procedure. Freshly passed 
 urine was treated with four times its volume of absolute alcohol, and filtered ; 
 to this clear filtered fluid an alcoholic solution of potash was added, and after 
 six, eight, or ten hours there was observed a crystalline efflorescence at the 
 bottom and on the walls of the vessel, together with a slight amorphous pre- 
 cipitate,, This deposit, when collected and dissolved in water, gave, on being 
 boiled with sulphate of copper and potash, a beautiful red precipitate of suboxide 
 of copper. That it is not, however, sugar, as Briicke supposes, which occasions 
 this reduction of the oxide of copper, seems obvious for the following reasons. 
 (1.) He found that the extent of the reduction varied in a direct ratio with the 
 amount of the crystalline efflorescence ; but potash-sugar does not separate 
 from an alcoholic fluid in a crystalline form (see p. 86). (2.) Again, to obtain 
 the reduction at once, he had to employ a boiling heat, whereas the presence of 
 sugar manifests itself at a temperature of 160 or less (see my remarks on the 
 precautions to be attended to in the application of Trommer's test in p. 86) ; 
 and while at an ordinary temperature sugar exhibits its reducing powers in 
 from two to twelve hours, in Briicke's cases no separation of the suboxide was 
 perceptible, even after the mixture had stood for twenty-four or forty-eight 
 hours ; although after a longer period a very trifling scarcely visible precipitate 
 was found. (3.) If we slightly acidify the watery solution of the efflorescence 
 with hydrochloric acid, minute, colourless crystals of uric acid are formed in a 
 few hours, and after their removal the fluid altogether loses its power of re- 
 ducing oxide of copper. 
 
 The main factor, then, in the reduction in these experiments is clearly uric 
 acid ; and Lehmann, who has carefully repeated Briicke's observations, suggests 
 that hypoxanthine, and some other substances which sometimes occur in traces 
 in the urine (such as taurylic acid, and aldehyde), may co-operate with the 
 uric acid in this action. 
 
334 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Inosite. 
 
 Leucine 
 and Tyro- 
 sine. 
 
 If the urine constantly, and for a considerable time, contain 
 an appreciable quantity of sugar, we may be tolerably cer- 
 tain (independently of other signs, such as an increased 
 quantity of urine, high specific gravity, &c.) that the case is 
 one of diabetes mellitus. 
 
 If, on the other hand, the urine only contains traces of 
 sugar, or if the presence of the sugar is only temporary or 
 intermittent, we should act very rashly in assuming that the 
 case was necessarily one of diabetes mellitus. In such cases 
 as these, the presence of sugar may be due to the excessive use 
 of saccharine or farinaceous food, to an abnormal condition of 
 the medulla oblongata, to a diminution of the respiratory 
 activity and of the consequent supply of oxygen to the system, 
 to an excessive production of sugar in the liver, to a sudden 
 stoppage of the secretion of milk *, or to a diminution of 
 the alkalies of the blood. 
 
 The effect of sugar, saccharine fruits, &c. in increasing 
 the quantity of the sugar in the urine of diabetic patients, 
 has been long known. Eecent investigations have shown 
 that coffee, wine, beer, and organic acids have a similar 
 action, while the accession of a febrile attack temporarily 
 diminishes the quantity of sugar. 
 
 Inosite has been found by Cloetta in the urine of a patient 
 with Bright's disease, who was being treated with drastic 
 purgatives ; and by Vohl, in a diabetic patient in whose urine 
 it partially replaced the ordinary sugar (glycose.) 
 
 Leucine and tyrosine have been found in a few instances in 
 the urine in cases of typhus, measles, and acute yellow atrophy 
 of the liver: leucine has also been found in alkaline albu- 
 
 * The statement of M. Blot (see note to p. 91), that sugar is usually present 
 in the urine during pregnancy and the puerperal state, and often during lacta- 
 tion, has not been confirmed. I am indebted to Mr. Jardine Murray, late 
 house-surgeon to the Edinburgh Maternity Hospital, for a very careful exami- 
 nation of the urine in thirteen cases, in reference to this point, the fluid being 
 obtained in most cases a very few hours before delivery. In no case could a 
 trace of sugar be detected j but in seven of the cases the urine was slightly 
 albuminous. 
 
THE URINE. 335 
 
 minous urine, passed by an epileptic patient with disease of 
 the spinal cord. In some of these cases the leucine was 
 partially decomposed into valerianate of ammonia, (see p. 3 1 ). 
 
 Bile-pigment, probably an admixture of cholepyrrhin and Bile-pig- 
 biliverdin, is found in the urine in almost all cases of icterus. 
 According to Vogel, the biliverdin is usually the prepon- 
 derating pigment, and sometimes we find biliverdin alone. 
 Since cholepyrrhin is probably the original pigment and 
 biliverdin only a derivative from it (see p. 96), we are led to 
 infer that in icterus the greater part of the bile-pigment under- 
 goes a change, either during its resorption, or subsequently 
 in the blood, or finally in its passage into the urine. 
 
 The presence of biliary acids in morbid urine is by no Biliary 
 means so rare as has generally been supposed. Until 
 very lately, it has been believed that they seldom occur in 
 the urine; but this may probably be, as Vogel suggests, 
 because they have been seldom sought for. Pettenkofer, 
 Enderlin, and Lehmann, have detected them, sometimes 
 unaccompanied by bile-pigment, in the urine in cases 
 of pneumonia; and so far as I know this was the only 
 disease in which they had been discovered, till Kiihne re- 
 cently proved by very careful experiments, both on jaundiced 
 patients and on dogs that were artificially jaundiced by liga- 
 turing the ductus cominunis, that cholic acid (not however in 
 a conjugated form as glycocholic or taurocholic acid) is 
 usually present in bilious urine. 
 
 We have already alluded to the question as to whether Ammonia, 
 ammonia is a normal constituent of the urine (see p. 322). 
 It is universally known that ammoniacal salts occur in 
 morbid alkaline urine ; but they are also occasionally found 
 in acid urine in cases of typhus, measles, and scarlatina. 
 Ammonia is almost always present in alkaline urine, for the 
 alkaline reaction either depends directly on ammonia pro- 
 duced (as in vesical catarrh) from decomposition of the urea, 
 or is due to the passage of alkaline carbonates into the urine, 
 
336 PHYSIOLOGICAL CHEMISTRY. 
 
 which rapidly induce a decomposition of the urea ; in the 
 latter way we can explain the invariable occurrence of a 
 little ammonia in the normally alkaline urine of herbi- 
 vorous animals, and in the urine of man after the administra- 
 tion of alkaline carbonates, citrates, tartrates, &c. 
 
 There is no satisfactory evidence that nitric acid ever occurs 
 in the urine, unless when it had been previously administered. 
 Variations (286.) The remarks which have been already made (see 
 quantity p. 323) on the quantity of water excreted daily by the kidneys 
 urine 6 a PPty almost equally to the urine itself. The quantity may 
 be determined either by weight or by fluid measure ; in this 
 country we almost always calculate it by fluid ounces, on the 
 continent it is most commonly reckoned by weight (grammes), 
 but sometimes by cubic centimetres (thirty of which nearly 
 equal one fluid ounce). The most careful and prolonged set 
 of experiments made on this subject are those of Dr. Thu- 
 dichum. They were made upon two individuals, (A) a man 
 aged 28 years, and weighing 11 stone; and (B) a man aged 
 28 years, and about 5 pounds heavier. Observations made 
 on A for 76 days gave as an average 69 ounces, the maxi- 
 mum being 100 and the minimum being 36 ounces; while 
 similar observations made on B for 57 days gave as the 
 average 61 ounces, the maximum being 92 ounces and the 
 minimum 35 ounces. Other determinations by Bischoff and 
 Vogel are lower. From 40 to 70 ounces may be said to be 
 the normal range. Measuring the urine in reference to the 
 weight of the individual, (which is undoubtedly the fairest 
 mode,) it has been found that for 1000 parts by weight an 
 adult male excretes daily 25*9 parts according to Winter, 
 24*24 parts according to Vogel, and 20-26 parts according to 
 Kaupp ; while, according to Scherer, a child excretes 47 parts 
 of urine for 1000 of weight. It appears from hourly obser- 
 vations made by various observers, that the excretion is most 
 abundant after dinner, reaches its minimum during the 
 night, and rises again in the forenoon. Cold fresh-water 
 
THE URINE. 337 
 
 bathing often increases it considerably for a short time, and 
 so, to a much less extent, does sea-bathing. The temperature 
 of the atmosphere also affects the excretion, most urine being 
 voided at low temperatures when the action of the skin is 
 comparatively inert. We possess little or no certain know- 
 ledge regarding the direct action of medicinal agents on the 
 excretion of urine.* 
 
 In disease the quantity of urine often deviates beyond the 
 normal range. 
 
 1. In almost all acute febrile affections the quantity of 
 urine is diminished, and does not begin to rise till the dis- 
 order begins to abate. The observance of the daily urine thus 
 affords an important prognostic indication. It is found that 
 it is almost solely the water that is diminished in these cases, 
 the daily solid constituents being comparatively unaffected. 
 
 2. Towards the fatal termination of most diseases, both 
 acute and chronic, the quantity of urine often sinks consider- 
 ably below the normal standard. 
 
 3. In dropsies we usually have a great diminution of the 
 urine. 
 
 4. The only diseases in which there is an excessive excre- 
 tion of urine are Diabetes mellitus, and D. insipidus. 
 
 (287.) It appears from numerous observations that in Variations 
 adults the daily amount of the solid constituents of the urine ^nount of 
 may vary from 35 to 80 grammes, according to the quantity su . lid con ~ 
 and nature of the food. The ingestion of much fluid aug- 
 ments the solid constituents. During the night less solid 
 constituents are passed than in the same number of hours 
 during the day. The main function of the kidneys being to 
 excrete nitrogenous matters and soluble salts, it is almost a 
 priori obvious that a highly nitrogenised (animal) diet and 
 
 * Hammond has carefully examined the action of digitalis, broom, squills^ 
 and colchicum on the urinary secretion ; and finds that while colchicum mate- 
 rially increases both the organic and the inorganic solids, the other drugs actually 
 diminish the excretion of organic matters. They all increase the quantity of 
 water. (Quoted in Journ. de Physiol. 1860, vol. iii. p. 227.) 
 
338 PHYSIOLOGICAL CHEMISTRY. 
 
 any circumstances that accelerate metamorphic action of the 
 tissues must increase the solid constituents of the urine, as 
 indeed has been rigorously demonstrated by the observations 
 of Lehmann, Bischoff, Rummel, Hammond, and others. When 
 the metamorphic action is checked, as is the case in many 
 forms of disease, the solid matters are diminished. When the 
 blood is poorer than natural in albunrinates and richer in 
 salts, the normal solid constituents are considerably dimi- 
 nished, as we see in Bright's disease (after the removal of the 
 albumen from the urine), and in cases in which saline solu- 
 tions have been injected into the veins of animals. In 
 diabetes we always have an excessive amount of solid consti- 
 tuents ; and the same is often the case in Bright's disease, if 
 we include the albumen. 
 
 The daily quantity of the mineral constituents is liable to 
 great variations ; it may range from 7 to 23 grammes, the 
 average being about 15 grammes, or nearly half an ounce. 
 
 It is unnecessary to refer to the conditions which modify the 
 amount of the collective salts, as we should merely have to 
 recapitulate what has been already stated regarding the in- 
 dividual salts. 
 
 (288.) We shall next consider the influence of certain phy- 
 siological relations, such as sex, age, food, &c., upon the 
 urinary secretion. 
 
 Influence It has been generally stated that the urine of women con- 
 tains more water and less urea and salts than that of man ; 
 it is doubtless true that the daily excretion of urea and salts 
 is less in women than in men generally ; but this difference 
 is due, not to anything special in the sex, but to the fact that 
 in man, owing to his greater weight and more active habits, 
 there is usually a greater disintegration of tissue than in 
 woman. The urine during pregnancy is distinguished by its 
 small amount of solid constituents, and by its especial poverty 
 in phosphate of lime (which is required for the foetal bones, 
 &c.). Becquerel never found it to possess a higher specific 
 
THE URINE. 339 
 
 gravity than 1-011. According to Lubanski and Hosier, the 
 urine during pregnancy is deficient in free acid, the reaction 
 being often neutral or alkaline ; Lehmann, however, found it 
 always acid in healthy women. In consequence of its watery 
 character, alkaline fermentation sets up in it earlier than in 
 ordinary urine ; and a glistening scum or membrane is usually 
 formed in the course of a day or two upon its surface, to which 
 the term kyesteine has been applied. This membrane, which 
 was at one time regarded as a certain evidence of pregnancy 
 (and which unquestionably is generally present in the urine 
 during pregnancy, although it is not exclusively connected 
 with that condition), is merely a conglomerated admixture of 
 triple phosphate crystals (phosphate of ammonia and mag- 
 nesia), and minute fungoid and confervoid growths. It is not 
 unfrequently formed on the surface of the urine of chlorotic 
 and anaemic non-pregnant women. 
 
 The urine at different periods of. life presents variations Of age. 
 in its character which correspond with the variations occurring 
 at different epochs in the general metamorphosis of the 
 tissues. It appear from the researches of Scherer, Bischoff, 
 and Eummell, that while men in the prime of life excrete 
 positively the largest amount of urinary constituents, the 
 largest quantity as compared with the weight is yielded by 
 children (in the ratio of nearly two to one). Except that 
 young children pass relatively much less phosphate of lime, 
 and possibly rather more hippuric acid, their urine does not 
 materially differ from that of adults. 
 
 The influence of the digestive process upon most of the Of the 
 individual constituents has been already noticed ; and al- pj.^^ 
 though the same remark applies to a great extent to the in- 
 fluence of different kinds of diet, the subject is one of such 
 importance that we shall notice it here more fully. 
 
 The most important investigations on the effects of differ- Of different 
 ent kinds of diet on the urine are those of Lehmann and f^. 
 Hammond. 
 
 Z 2 
 
340 PHYSIOLOGICAL CHEMISTRY. 
 
 In a prolonged series of experiments, to which we have 
 already referred (see p. 43), Lehmann attempted to ascertain 
 the influence which varieties of diet (animal, vegetable, and 
 non-nitrogenous) exert on the character of the urine generally, 
 and on its special quantitative relations. Having first deter- 
 mined the composition of the daily urine during his ordinary 
 mixed diet, he analysed for twelve days the urine while he 
 lived on a purely animal diet (chiefly of eggs), and for twelve 
 days while living on a purely vegetable diet ; and he further 
 made two analyses, while living on a perfectly non-nitro- 
 genous diet (fat, milk-sugar, and starch). 
 
 The following table expresses the mean results (in 
 grammes) : 
 
 Solid Con. Urea. Uric Acid. Extractive Matters 
 
 stituents. and Salts. 
 
 On a mixed diet , 67*82 32-498 1-183 12*746 
 
 On an animal diet . 87*44 53'198 1-478 7'312 
 
 On a vegetable diet . 59-24 22-481 1-021 19-168 
 
 On a non-nitrogenous diet 4 1-68 15408 0*735 17-130 
 
 From these researches he draws the following conclu- 
 sions : 
 
 (1.) The solid constituents are much increased by animal 
 food, while they are considerably decreased by a vegetable 
 diet, and still more so by a non-nitrogenous one. 
 
 (2.) The urea is similarly affected. 
 
 (3.) The uric acid is not essentially affected by the nature 
 of the food. 
 
 (4.) The sulphates and phosphates which are discharged 
 correspond very nearly in quantity with the nitrogenous 
 matters which have been taken ; after the almost exclusive 
 use of protein-compounds, the quantity of these salts in the 
 urine is considerably increased. 
 
 (5.) Hence it follows that the other organic constituents of 
 the urine, that is to say the extractive matters, must be very 
 much diminished during an animal diet, and these investiga- 
 tions show that the use of vegetable food causes a positive 
 augmentation of such substances. 
 
THE URINE. 341 
 
 (6.) After the use of purely animal food the physical 
 properties of the urine precisely resemble those of this secre- 
 tion in the carnivora ; that is to say, the secretion is of a very 
 light amber-yellow colour, has a strong acid reaction, and 
 contains little or no lactic acid, and no hippuric acid. On 
 the other hand, after a course of vegetable diet, a very great 
 portion of the free acid disappears ; the urine contains a 
 large amount of dark-coloured extractive matter, and hence 
 is of a brownish-red tint ; it is also somewhat turbid from the 
 separation of earthy phosphates, or rapidly becomes so on 
 boiling, and almost always contains alkaline lactates with 
 oxalate of lime. 
 
 Dr. Hammond first ascertained the normal composition of 
 his urine, while living on his ordinary diet, by analysing it 
 for five successive days ; he then lived for ten days solely on 
 albumen and water, and analysed his urine each day; after 
 an interval of a month he lived for ten days on cooked starch 
 and water, analysing the urine each day ; twenty-five days 
 after the termination of this set of experiments he commenced 
 living on gum and water, which, much to his regret, he- was 
 obliged to discontinue, " owing to the debility and great de- 
 rangement of health produced " at the end of the fourth day, 
 the urine being analysed on each of these days. 
 
 The following table gives his mean results expressed in 
 troy grains : 
 
 Ordinary Diet. Albumen. Starch. Gum. 
 
 Solid constituents . 1097'58 988-87 516'98 440-50 
 
 Urea . , . 694-63 715-19 215-35 297'13 
 
 Uric acid . . H'67 20'76 7-53 8'81 
 
 Chlorine . . 138-13 8-86 16'71 19'21 
 
 Sulphuric acid , 45-18 16-92 973 11-12 
 
 Phosphoric acid . 55-85 22-04 13-66 12-28 
 
 Kesidue . . 194-37 215-19 252-86 67'16 
 
 The high numbers for urea, &c., during his ordinary diet 
 are explained by the facts that Dr. Hammond's normal weight 
 
 z 3 
 
342 PHYSIOLOGICAL CHEMISTRY. 
 
 is between 14 and 15 stone, and that he takes animal food 
 three times daily. 
 
 As these experiments will again claim our notice in the 
 chapter on (< Nutrition," it will be sufficient to mention that 
 the albumen was obtained from the serum of bullocks' blood 
 by boiling it, and was consequently ingested in the coagulated 
 form. The water was either distilled, or obtained by melting 
 snow, and nothing was taken during the 10 days of the 
 albumen-experiment but washed coagulated albumen and 
 water. On the 7th day albumen appeared in the urine, and 
 continued, in increasing quantity, to the close of the experi- 
 ment. Amongst the other points most worthy of notice in 
 this experiment, may be mentioned (1.) The fact that the 
 urea obviously varied in a direct ratio with the amount of 
 ingested albumen till the health got considerably disturbed. 
 
 Thus on the 
 
 Grains. Grains. 
 
 5th day the ingested albumen was 6,680 and the urea 721 
 2nd 8,653 922 
 
 1st 8,729 812 
 
 3rd 11,285 1,162 
 
 4th 12,725 1,251 
 
 (2.) There is no definite ratio between the uric acid and 
 either the urea or the ingested albumen. (3.) No chlorides 
 being taken during this experiment, there was a regular and 
 steady daily fall in the excreted chlorine, it standing during 
 the 10 days as follows: 30-6, 21-6, 10-5, 5-4, 5-0, 4-2, 3-6, 
 3-4, 2-4, and 2-1 grains. In the starch-experiment sugar was 
 found in the urine on the 5th day, continued in increasing 
 quantity to the 10th and last day of the exclusive starch-and- 
 water diet, and remained in the urine five days after the 
 close of the experiment : the urine remained acid during the 
 starch-diet. The urea fell tolerably regularly from the begin- 
 ning to the end of the experiment, being 422 grains on the 
 
THE UEINE. 343 
 
 1st day, 204 on the 4th, 157 on the 7th, and 122 on the 10th 
 day, and was unaffected by the quantity of ingested starch. 
 The uric acid presented no definite law, but was present in 
 far less quantity than during the albuminous diet. In that 
 case the maximum,, mean, and minimum were 29-2, 20-8, and 
 11*3 grains; while on the starch diet they were 9*5, 7*5, and 
 5*2 grains. The chlorine diminished regularly, as in the 
 former experiment; and in this case the sulphuric and 
 phosphoric acids similarly diminished from 30*4 and 27*2 to 
 2*3 and 5 '3 grains, while in the former case they were 
 slightly modified by the amount of albumen, although on the 
 whole they sunk with tolerable continuity, the sulphuric 
 acid from 28'7 to 8'4, and the phosphoric acid from 36*2 to 
 9 '2 grains. 
 
 Dr. Hammond's observations confirm the generally ac- 
 cepted view that gum is incapable of assimilation ; hence in the 
 last set of observations the urinary constituents must have 
 been solely derived from the pre-existing tissues of the body. 
 
 (289.) We now proceed to notice the changes which the Urine in 
 urine undergoes in certain general forms of disease, which 
 express upon it definite and well marked characteristics. 
 
 The urine in fever, that is to say, in that group of Febrile 
 symptoms which accompany almost all acute diseases, presents 
 distinct peculiarities. Febrile urine is usually more deeply 
 coloured than usual (being of a reddish tint), and has a 
 stronger odour, a higher specific gravity, and a more decided 
 acid reaction than normal urine. As long as the febrile 
 symptoms continue, less than the normal quantity of urine 
 is generally secreted by the kidneys, and the urine is con- 
 centrated, because there is a greater relative diminution of 
 water than of solid constituents. The constant characters of 
 such urine are the diminution, both relative and absolute, 
 of the inorganic salts, and especially of the chloride of sodium, 
 and the augmentation of the uric acid and urates. Even when 
 febrile urine does not deposit urates, it is always richer in 
 
344 PHYSIOLOGICAL CHEMISTRY. 
 
 uric acid than other urine. The urea is increased in some 
 febrile urines (see p. 45), and probably diminished in others. 
 The extractive matter is usually increased, and lactic acid is 
 often present. 
 
 In contrast to febrile urine, Becquerel has distinguished an 
 anaemic urine, which is connected with a deficiency or poverty 
 of the blood, and occurs in various forms of debility. Anaemic 
 urine is pale and watery ; it has only a slight acid reaction, 
 and readily becomes alkaline ; the urea and uric acid are 
 much diminished, and there is a decrease, to a less degree, 
 in the salts, while the extractive matters differ only slightly 
 from the normal average. 
 
 We shall not attempt to describe the modifications of the 
 urine in individual diseases, for even in health, and still more 
 in disease, this fluid is of so variable a nature, that it is often 
 impossible to determine whether the alterations noticed in 
 its condition actually arise from a morbid process, or only 
 from incidental influences. " If," says Lehmann, " we care- 
 fully observe the changes which often occur in the urine in 
 the course of the same day, not merely in typhus or any 
 acute exanthema, but also in inflammations which are running 
 their ordinary course, we see that the urine is much more 
 regulated by the transient condition of the organism, external 
 influences, and temporary symptoms, than by the nature of the 
 morbid process. Thus, the albumen in the urine in Blight's 
 disease is considerably diminished, and may even almost dis- 
 appear, if the chronic form of this disease is associated with an 
 affection giving rise to inflammatory fever. The urine which 
 is so characteristic of this form of disease, loses almost all 
 its distinctive properties, and assumes, both in a qualitative 
 and quantitative point of view, the character of inflammatory 
 febrile urine. It appears therefore to be more rational to 
 limit our examination of the composition of the urine to 
 certain morbid conditions and individual groups of symptoms, 
 and to compare together the various analytical results thus 
 
THE UKINE. 345 
 
 obtained, than to attempt to extend similar observations to 
 different forms of disease." 
 
 Again, every one who has paid any attention to the 
 chemical composition of the urine, must have observed that 
 such substances as albumen, oxalate of lime, lactic acid, &c., 
 are not characteristic of specific diseases, or even of specific 
 groups of disease, but merely of certain processes or s} T mp- 
 toms accompanying disease : and if the more abnormal 
 substances which are occasionally present, such as red, green, 
 blue or black pigments, inosite, cystine, leucine, tyrosine, &c., 
 do indicate the existence of special forms of disease, we have 
 hitherto been unable to trace the connection. 
 
 (290.) Many analyses have been made of the urinary secre- Urine of 
 tion of the lower animals. It is sufficient here to indicate the 
 most important of the general results which have been obtained. 
 
 The urine of the pig, which may be regarded as the type 
 of the omnivora (but whose food when domesticated is 
 chiefly vegetable), is clear, almost devoid of odour, distinctly 
 alkaline, effervesces on the addition of acids, and becomes 
 turbid on boiling from the conversion of the alkaline bicarbo- 
 nates into simple carbonates. It contains neither uric nor 
 hippuric acid, no salts of ammonia, and mere traces of phos- 
 phates. Sulphates and alkaline chlorides are tolerably 
 abundant, and alkaline lactates are apparently contained in 
 it. Its solid constituents range, according to Boussingault 
 and Von Bibra (who have independently analysed this fluid), 
 from 1-804 to 2'086-g- of which from 0-29 to 0'49 are urea. 
 
 The urine of the carnivora approaches much more closely to 
 the human type. When fresh, it is clear, of a light yellow 
 colour, and has a disagreeable odour, a nauseous bitter taste, 
 and an acid reaction. It contains much urea, little pigment, 
 and little or no uric acid. (In dogs * the uric acid seems to be 
 
 * A thorough series of analyses of the urine of the dog under different con- 
 ditions of diet, has been made by Voit. (See Bischoff u. Voit, Die Gesetze der 
 Ernahrung des Fleischfressers, 1860, pp. 267288.) 
 
346 PHYSIOLOGICAL CHEMISTRY. 
 
 partly replaced by an acid whose probable formula is 
 C 16 HN0 5 , and which we may name cynuric acid.) By 
 feeding carnivorous animals on vegetables we can render 
 their urine turbid, alkaline,, and generally like that of the 
 herbivora. 
 
 The urine of herbivorous animals is yellow, turbid, of an 
 unpleasant odour, and alkaline. In addition to urea, it 
 contains hippuric (but no uric) acid, lactates of the alkalies, 
 carbonates of the alkalies (chiefly potash) and earths, oxalate 
 of lime, and a very small quantity of phosphates. By placing 
 herbivorous animals on a purely animal diet, we can make 
 their urine resemble that of the carnivora. Thus, the urine 
 of the calf while living solely on milk is clear and acid, and 
 in addition to urea, contains uric (but no hippuric) acid, crea- 
 tinine, and a considerable quantity of allantoine (see p. 49), 
 a large amount of phosphate of magnesia and potash-salts, but 
 very little of the alkaline phosphates, sulphates, or soda-salts. 
 
 The urine of birds, which usually forms a white outer 
 coating to the solid excrements, consists essentially of the 
 urates of ammonia and lime, together with phosphates, 
 sulphates, and chlorides. 
 
 The urine of frogs is fluid, and contains urea, chloride of 
 sodium, and a little phosphate of lime. 
 
 The urine of serpents, which is often passed independently 
 of the solid excrement, is at first pulpy, but soon becomes 
 firm and dry. It consists mainly of urates of the alkalies, 
 a little urea, and earthy phosphates. (Prout found more than 
 90^- of uric acid in the urine of the boa constrictor.) 
 
 The urine of tortoises, when they have been kept for some 
 time without food, is a very pale yellowish green fluid, with 
 a well-marked acid reaction, which on cooling deposits a 
 sediment, which redissolves on the application of warmth ; 
 if they have been recently fed, their urine is neutral, or faintly 
 alkaline and less clear, and deposits a sediment which is only 
 partially soluble in boiling water. The main ingredients 
 of their urine are urea, urates of soda, ammonia and lime, 
 
THE UKINE. 347 
 
 hippuric acid, a little fat, phosphates, sulphates, and chlo- 
 rides. 
 
 The urine of several Saurians has been examined. In 
 that of Lacerta agilis Scholz found 94 of uric acid, 2 of 
 ammonia, 3'33^- of phosphate of lime, and O67-- of sand. Prout 
 analysed the urine of the chameleon and iguana, and ob- 
 tained similar results ; and the urine of the crocodile has 
 been separately examined by Drs. John Davy and W. Moore : 
 it contains a large quantity of uric acid and urates, but no 
 urea ; in Dr. Moore's case albumen was also present, but this 
 was doubtless abnormal. 
 
 In the Invertebrata we often find urinary constituents (uric 
 acid and urates) mixed with the excrements, and we not un- 
 frequently meet with uric-acid crystals in examining certain 
 glandular structures, which we must consequently regard as 
 acting the part of kidneys, as for instance in the Malpighian 
 vessels of insects, spiders, and myriapods, in the glandular 
 venous appendages of the cephalapods, in Cuvier's mucus- 
 gland in the gasteropods, and in Boj anus's organ * in the 
 lamellibranchiate mollusks. 
 
 (291.) Although it does not enter into the scope of the Sketch of 
 present volume to describe analytical details, yet a general of unne. 
 knowledge of the chemistry of the urine is so important to 
 the medical practitioner, that I shall so far deviate from my 
 prescribed course, as to indicate the general steps to be pur- 
 sued for the detection of the ordinary normal and abnormal 
 ingredients of that fluid. 
 
 1. After having noted the specific gravity, we ascertain the 
 reaction of the urine by test-paper. 
 
 (a.) If the urine is acid and contains no sediment we pro- 
 ceed according to 2. 
 
 (6.) If the urine is acid and sedimentary, we allow the 
 
 * It seems well established by the independent chemical investigations of 
 Garner, Von Hessling, Von Babo, Will, and Von Gorup-Besanez, that this is a 
 urinary organ. Schlossberger, however, failed in detecting any uric acid in a 
 large brown concretion obtained from this organ in Pinna nobilis. 
 
348 PHYSIOLOGICAL CHEMISTRY. 
 
 sediment to deposit itself, decant off the urine (or filter if requi- 
 site) and proceed according to 2. The sediment must be exa- 
 mined microscopically according t the rules given in pp. 357 
 and 375. 
 
 (c.) If the urine is neutral or alkaline, it generally contains 
 a sediment which must be examined with the microscope, while 
 we proceed with the decanted or filtered fluid according to 2. 
 
 2. We boil a small quantity of the urine in a test-tube, 
 having previously acidified it with acetic acid if its own 
 reaction was not acid. If a coagulum is formed which does 
 not dissolve on the addition of a drop of nitric acid, it must 
 consist of albumen. In this case we take a larger quantity of 
 urine, about three ounces, remove the albumen by boiling, 
 filter, and treat the filtrate according to 3. 
 
 The coagulum may be 
 
 (a.) White, in which case it consists of pure albumen. 
 
 (6.) Greenish, in which case bile-pigment is probably 
 present ; or, 
 
 (c.) Brownish-red, in which case blood is probably present, 
 and the sediment should be carefully examined for blood-discs. 
 
 3. About two ounces of clear acid or acidified urine, freed 
 from any sediment or from albumen, must be evaporated in a 
 water-bath to the consistence of a thick syrup, and extracted 
 with alcohol. We filter the solution thus obtained, return 
 the insoluble residue, after washing it with alcohol, to the 
 evaporating basin, and test both the solution and the residue 
 as follows : 
 
 (a.) One-third of the alcoholic solution is evaporated 
 to a very thick syrup, and tested by nitric or oxalic acid for 
 urea (see p. 40). 
 
 (6.) Two-thirds are treated with oxalic acid and are evapo- 
 rated almost to dryness. The residue is then extracted with 
 ether, to which about one-sixth of alcohol has been added. 
 If we evaporate the ethereal solution to dryness, dissolve the 
 residue in a few drops of water, filter, and allow the solution 
 
THE URINE. 349 
 
 to evaporate spontaneously in a watch-glass, we shall obtain 
 crystals of hippuric acid, if any is present. If any fat is pre- 
 sent it will be found on the filter. 
 
 (c.) The residue insoluble in alcohol is treated with dilute 
 hydrochloric acid and filtered. 
 
 (aa.) The filtrate contains the earthy phosphates and 
 other salts; the former may be precipitated by neutralisa- 
 tion with ammonia. 
 
 (bb.) The residue on the filter contains uric acid and 
 mucus. These may be separated by washing them off the 
 filter into a small test-tube, adding two or three drops of a 
 soda-solution, warming, and filtering. 
 
 (a.) The substance that still remains undissolved is 
 mucus. 
 
 (/&) The filtrate contains urate of soda, which, on the 
 addition of hydrochloric acid, yields crystals of uric acid, 
 whose character may be further tested by the microscope 
 and by the murexide reaction. 
 
 4. If the urine is of a dark brown or greenish tint, if it 
 froths much when shaken, and if it communicates a yellow or 
 green tint to a bit of filtering paper moistened in it, we must 
 suspect the presence of bile, which may be further tested for 
 as follows : 
 
 (a.) We place some of the suspected urine in a conical 
 glass, and quietly drop into it some fuming nitric acid. If we 
 observe that the fluid assumes various colours, becoming 
 green, blue, violet, red, and finally yellow, we may be certain 
 that these changes are due to the oxidation of the chole- 
 pyrrhin or brown-colouring matter of the bile. 
 
 (6.) A second portion is precipitated with acetate of lead ; 
 the precipitate is collected on a filter, washed, dried, and 
 treated with alcohol, to which a few drops of sulphuric acid 
 have been added. If the fluid, after filtration, have a green 
 tint, biliverdin, or the green colouring matter of the bile, is 
 present. 
 
350 PHYSIOLOGICAL CHEMISTRY. 
 
 (c.) We take a third portion, about half an ounce, evapo- 
 rate it in the water-bath to dryness, extract it with alcohol, 
 evaporate the alcoholic solution, dissolve the residue in water, 
 add three or four drops of syrup (1 part of sugar to 4 of 
 water), and theji a little strong sulphuric acid, taking care 
 that the temperature does not rise much above 120. If the 
 fluid, after becoming turbid, assumes a red or purple tint, we 
 have evidence of the presence of the resinous acids of the bile. 
 
 5. If from the high specific gravity or for any other reason 
 we suspect the presence of sugar, we proceed as follows : 
 
 (a.) We apply Trommer's test of sulphate of copper and 
 solution of potash (see p. 85) ; and if the quantity of sugar 
 is very small, and the reactions doubtful, we must follow the 
 rules laid down in p. 86. 
 
 (6.) Or we boil a little urine in a test tube with an equal 
 quantity of solution of potash, when if sugar is present a 
 sherry brown colour is produced. This is, however, not so 
 certain a test as Trommer's.* 
 
 6. We treat half an ounce of urine with half its volume 
 (or more) of strong hydrochloric acid. If a dark colour is de- 
 veloped, and after a time a blue powder deposited, we have 
 evidence of the presence of indigo. 
 
 7. To test for the presence of the inorganic ingredients, we 
 may evaporate a portion of the urine (an ounce or less will 
 suffice) to dryness, mix it with a little spongy platinum f , and 
 heat it till all the carbonaceous matter is burnt off. We boil 
 the residue in water, filter, and proceed as follows : 
 
 (a.) We acidify one portion of the filtrate with hydro- 
 chloric acid, and add chloride of barium. A fine white pre- 
 cipitate indicates the presence of sulphuric acid. (Sulphate of 
 baryta.) 
 
 * We must not, however, forget that uric acid possesses a slight power of 
 reducing oxide of copper. See p. 333. 
 
 f The spongy platinum is added to ensure free and abundant access of air 
 to the interior of the heated mass. 
 
THE URINE. 351 
 
 (b.) We acidify another portion with nitric acid, and add 
 nitrate of silver ; a white curdy precipitate indicates the pre- 
 sence of chlorine. (Chloride of silver.) 
 
 (c.) We treat a third portion with acetate of soda, acetic acid, 
 and a drop of a solution of perchloride of iron ; a yellowish 
 white gelatinous precipitate indicates the presence of phos- 
 phoric acid.* (Phosphate of iron.) 
 
 (d.) We evaporate the remainder of the watery solution to 
 dryness, and heat a portion of the saline mass on a piece of 
 platinum wire in the inner flame of the blow-pipe. A yellow 
 coloration of the apex of the flame indicates the presence of 
 soda. 
 
 (e.) The remainder of the saline mass may be dissolved in 
 a few drops of water, and bichloride of platinum added ; if 
 a yellow crystalline precipitate is formed, potash is present. 
 
 8. The residue which did not pass through the filter in 7 
 is warmed in water containing hydrochloric acid, and filtered, 
 and we test the filtrate as follows : 
 
 (a.) A portion of the solution is boiled with a drop of 
 nitric acid, and sulphocyanide of potassium is added : the de- 
 velopment of a red colour indicates the presence of iron. 
 
 (6.) We treat the remainder with an excess of acetate of 
 soda, and test with oxalate of ammonia for lime. 
 
 (c.) The lime being precipitated by the last operation, we 
 filter and add ammonia to the filtrate: a white crystalline 
 precipitate indicates the presence of magnesia in the form of 
 phosphate of magnesia and ammonia. 
 
 * If we add perchloride of iron to a solution of phosphates, acidified with 
 free acetic 'acid, we obtain a yellowish- white gelatinous precipitate of phosphate 
 of peroxide of iron. As this compound is soluble in all acids except acetic 
 acid, we must be careful that no other free acid is present in a solution from 
 which we wish to precipitate the phosphoric acid by perchloride of iron. If any 
 other free acid should be present, we treat the fluid with acetate of soda and 
 pure acetic acid before applying the test, so as to guard against the possible 
 solution of the precipitate. 
 
352 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Most of the reactions in 7 and 8 may be exhibited, although 
 with less distinctness, in the original urine. 
 
 Tabular (292.) We have endeavoured in the following table to bring 
 
 view of the . . 11,1 i > 
 
 daily urine, clearly into view at a single glance the average daily excre- 
 tion of the urinary constituents in an adult man of ordinary 
 weight, viz. about eleven stone. In the case of the more im- 
 portant constituents, the normal maxima and minima have 
 also been given. 
 
 Quantity in 24 hours 
 
 Specific gravity . 
 
 Solid constituents 
 
 Urea 
 
 Uric acid . 
 
 Hippuric acid 
 
 Xanthine 
 
 Hypoxanthine . 
 
 Creatinine 
 
 Creatine 
 
 Min. Mean. 
 
 Max. 
 
 40 
 
 52 
 
 70 fluid oz. 
 
 1-005 
 
 1-020 
 
 1-030 
 
 850 
 
 935 
 
 1020 grains. 
 
 450 
 
 520 
 
 620 
 
 4 
 
 (or less) 8 * 
 
 15 
 
 . 
 
 . 33* 
 
 9 
 
 , 
 
 traces. 
 
 
 7-0 
 4-5 
 
 Extractive matters f very variable, according to diet, &c. 
 Chlorine . 
 
 (or Chloride of sodium 
 Sulphuric acid . 
 Phosphoric acid . 
 Earthy phosphates 
 Ammonia (?) 
 Iron .... 
 Silica ..... 
 
 Fluorine 
 
 Gases ..... undetermined. 
 
 . ." 
 
 . 160 
 
 
 
 . 266) 
 
 
 23 
 
 32 
 
 38 
 
 37 
 
 54 
 
 100 
 
 . 
 
 . 15 
 
 
 4-6 
 
 11 
 
 18-6 
 
 t 
 
 traces. 
 
 
 * This is Weissmann's determination for a mixed diet (see p. 305). I suspect 
 it is far above the ordinary quantity. 
 
 f Including Scharling's oxide of omichmyle, Stadeler's four acids, (viz. 
 phenylic or carbolic acid, taurylic acid, damaluric acid, and damolic acid,) 
 formic acid (?), butyric acid (?), urine-pigments, trimethylamine, aldehyde, &c. 
 
THE URINE. 353 
 
 (293.) Under the term urinary sediments we include all Urinary 
 those substances which occur in a non-dissolved state in the 
 urine. These substances are at first usually suspended in the 
 fluid, but after a longer or shorter time they gradually be- 
 come deposited and form a precipitate. The rapidity and 
 completeness of the precipitate vary with the size and density 
 of the suspended particles. To very slight sediments, con- 
 sisting of extremely minute molecules, and almost disappear- 
 ing on shaking the urine without rendering the fluid turbid, 
 we often apply the term cloud or cloudiness ; while, on the 
 other hand, if the individual particles are sufficiently large to 
 be distinguished with the naked eye, we apply the term sand 
 or gravel to the sediment. 
 
 Urinary sediments are of such extreme importance in 
 relation to practical medicine, that we shall notice them at 
 considerably greater length than their mere physiological 
 value would warrant. They frequently enable the physician 
 to recognise at a glance important changes in the urine, which 
 would (without their aid) require for their detection elaborate 
 chemical processes. 
 
 The study of the urinary sediments has (as Vogel* has clearly 
 pointed out) a double application in semecology. 
 
 (1.) From the investigation of these sediments we can import 
 
 draw sure conclusions regarding special changes that are 
 
 going on in the general metamorphosis of the tissues of our stud y- 
 patients. They show us that an excessive quantity of certain 
 substances (as, for instance, uric, hippuric, or oxalic acid) is 
 being discharged by the urine, and is consequently being 
 produced in the organism ; and they show us this by a pro- 
 cess which involves no loss of time, and which is almost always 
 one of absolute certainty. 
 
 (2.) We recognise from their investigation certain local 
 morbid processes going on in the uropoietic viscera. Thus, 
 for instance, from a purulent sediment we infer that suppura- 
 
 * Anleitung z. Analyse des Harns, 3d. Ed. 1858, p. 264. 
 A A 
 
354 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 tion is occurring in some portion of the urinary organs ; a 
 sediment, consisting of cylindrical casts or tubes, informs us 
 of certain morbid changes in the structure of the kidneys ; 
 and if the ordinary symptoms reveal the presence of stone in 
 the bladder, we can often ascertain its nature from an ex- 
 amination of the gravel that is passed. 
 
 Most urinary sediments are not formed until after the 
 urine has been discharged and has cooled ; some, however, 
 are formed in the urinary organs, and under favouring cir- 
 cumstances may give rise to urinary concretions. Hence it 
 is often a point of great consequence to ascertain whether a 
 sediment, occurring in a specimen of fresh urine, has been 
 formed before or after its discharge from the body. 
 
 We briefly noticed in p. 2 96 -the changes which the urine, 
 when allowed to stand for some time, spontaneously under- 
 goes, in consequence of the establishment in it of the acid and 
 alkaline urinary fermentations first described by Scherer*, 
 and the connexion between these changes and the formation 
 of urinary sediments. 
 
 The most common of all the sediments is that formed by 
 urate of soda, which is often deposited after a short time from 
 urine which, when passed, was perfectly clear. This deposi- 
 tion might arise, and often does actually arise, from the pre- 
 sence of so large a quantity of urate of soda in the urine, that 
 at an ordinary temperature the whole of it cannot be retained 
 in solution, as is shown by the disappearence of the sediment 
 on the application of a gentle heat, or on the addition of 
 water, or of a less concentrated specimen of urine. But it 
 frequently happens that the urine remains clear long after 
 its temperature has fallen to that of the surrounding air, and 
 that a sediment of urate of soda begins to be deposited after 
 twelve, eighteen, or twenty-four hours. The cause of the 
 deposition in this case must, therefore, be sought for else- 
 where ; and Lehmann thinks that it may be traced to the 
 pigment and extractive matters, which, according to Scherer's 
 
 * Ann. d Ch. u. Pharm. vol. xlii. p. 171. 
 
THE URINE. 355 
 
 observations, likewise occasion the deposition of free uric acid. 
 Lehmann believes that the pigment and extractive matters 
 increase the solubility of the urate of soda, and that their de- > 
 
 composition exerts an influence on this salt, and renders it 
 less soluble. There is no doubt that the urinary pigments 
 very readily decompose in the presence of air, and that in 
 their decomposition a little free acid is always developed. If 
 we expose to the air a colourless sediment containing no free 
 uric acid, we observe that when lying moist upon a filter it 
 assumes a beautiful red colour, and if we now try to dissolve 
 it in water we find that it contains a certain amount of uric- 
 acid crystals. This phenomenon is readily explained by sup- 
 posing that the free acid, liberated by the decomposition of 
 the adherent pigment, extracts from the urate of soda a little 
 of its base, leaving a solution of the neutral salt. Lehmann 
 believes that the urate of soda, naturally existing in the urine, 
 is a neutral salt, and that by the abstraction (in the mode that 
 lias just been described) of a portion of its base it is con- 
 verted into an acid salt or super-urate of soda. 
 
 Scherer, in the memoir to which we have referred, has un- Formation 
 questionably given the true explanation of the mode of for- sediments 
 mation of uric-acid sediments ; showing that they are solely 
 dependent on the decomposition of the pigment. In perfectly 
 fresh urine we scarcely ever see a uric-acid sediment, but 
 every urine, as it undergoes acid fermentation, sooner or later 
 deposits crystals of free uric acid. The free acid produced 
 (probably) by the action of the vesical mucus on the pigment, 
 decomposes the comparatively insoluble urates (as mentioned 
 in the last paragraph), and by combining with a portion of 
 the base liberates uric acid, which at once crystallises. There 
 is reason to believe that oxalate of lime is also formed, or at 
 all events separated during this acid fermentation ; for while 
 crystals of oxalate of lime are very seldom found in a perfectly 
 fresh specimen of urine, they can very often be detected 
 intermingled with uric-acid crystals after the fluid has stood 
 for some time. 
 
 A A 2 
 
356 
 
 PHYSIOLOGICAL CHEMISTKT. 
 
 The acid fermentation having at length reached its maxi- 
 mum (the time varying from days to even a few weeks), the 
 free acid gradually disappears, the surface of the fluid be- 
 comes covered with thread-like fungi, confervae, and algae,, the 
 reaction becomes neutral, then alkaline, and the crystals of 
 uric acid at length disappear, and are replaced by a mixed 
 sediment of a perfectly different nature. The ammonia pro- 
 duced by the decomposition of th'e urea throws down the 
 Formation earthy phosphates, the phosphate of lime falling unchanged, 
 phatic an( i the phosphate of magnesia combining with ammonia to 
 sediments. f orm fa e beautiful and well-known crystals of phosphate of 
 ammonia and magnesia, or triple phosphate. Another por- 
 tion of the ammonia at the same time combines with the uric 
 acid (which had formed the previous sediment), and gives rise 
 to the production of .urate of ammonia. At this stage the 
 urine effervesces on the addition of an acid, and has almost 
 entirely lost its original yellow tint, in consequence of the 
 decomposition of most or all of the pigment. 
 
 Such is the ordinary course of the alkaline fermentation ; 
 there are, however, occasional cases in which it occurs much 
 earlier, and without a pre-existing acid fermentation ; it may 
 even occur within the urinary bladder, in which case the 
 urine is alkaline at the moment of its emission. (We must, 
 however, be careful not to confound these cases with those 
 in which the urine has been made alkaline by the administra- 
 tion of vegetable salts of potash or soda.) 
 
 From the preceding observations we draw the following 
 conclusions : 
 
 (1.) The acid fermentation consists essentially in the pro- 
 duction of free acid (lactic, or acetic, or both) from the pig- 
 ment by the catalytic action of vesical mucus, and gives rise 
 to the deposition of : 
 
 (a.) Free uric acid. 
 
 (/3.) Acid urates (chiefly urate of soda). 
 
 (7.) Oxalate of lime. 
 
THE URINE. 357 
 
 (2.) The alkaline fermentation is essentially due to the 
 formation of carbonate of ammonia in the urine, which causes 
 the disappearance of the sediment of uric acid, and its re- 
 placement by 
 
 (a.) Phosphate of ammonia and magnesia (triple 
 
 phosphate). 
 
 (/3.) Phosphate of lime. 
 (7.) Urate of ammonia. 
 
 We may divide the urinary sediments into (1.) the unorgan- 
 ised, and (2.) the organised deposits. 
 The unorganised sediments include : 
 
 Uric acid, Unorgan- 
 
 ised sedi- 
 
 1 he urates (chiefly urate of soda), ments. 
 
 Hippuric acid, 
 
 Oxalate of lime, 
 
 Earthy phosphates (phosphate of lime, phosphate of 
 
 ammonia and magnesia), 
 Cystine, 
 Xanthine, 
 
 Hypoxanthine (formerly known as guanine), 
 Tyrosine* 
 
 The organised sediments include : 
 
 Mucus and epithelial scales, Organised 
 
 Blood-corpuscles, 
 
 Pus-corpuscles, 
 
 Cancerous and tubercular matter,. 
 
 Fibrinous casts of the tubes of the kidney, 
 
 Spermatozoa, 
 
 Fungi, infusoria, &c. 
 
 We shall consider these substances in the order in which we 
 have placed them in the preceding list. 
 
 Uric acid never occurs as a sediment except in strongly Uric acid, 
 acid urine. (We are now speaking of its occurrence as an 
 
 A A 3 
 
358 PHYSIOLOGICAL CHEMISTRY. 
 
 ordinary sediment before the establishment of acid fermenta- 
 tion.) It may occur, for instance, where free lactic acid is 
 present (see p. 22), the lactic acid decomposing some of the 
 urates, combining with soda, and liberating free uric acid. 
 This process may even occur within the bladder and other 
 urinary organs. The sediment is usually of a deep yellow, 
 a reddish orange, or a brown colour, sometimes of a pale 
 yellow tint, but never colourless. The crystals are large 
 enough to be recognised by the naked eye, and their form, as 
 seen through the microscope, is shown in Plate III) fig. 4 (see 
 p. 63). If in any particular case the form should not be 
 sufficiently obvious and characteristic, we must dissolve the 
 sediment in a drop of potash-solution on a glass slide, and 
 add a drop of hydrochloric acid, when we shall get more dis- 
 tinct crystals. To separate them from urates we have only 
 to warm the fluid, and at once filter, when the urates, dis- 
 solved by the heat, will pass through the filter, and the 
 uric-acid crystals will be retained on it. If we wish to 
 strengthen our microscopical proof by a chemical one, we can 
 apply the test for the production of murexide (see p. 65). 
 
 It is very important to ascertain whether the sediment (and 
 this remark applies equally to all the sediments whose con- 
 stituents enter into the composition of urinary concretions) is 
 formed before or after the urine has been discharged : as in the 
 former case such urine would, unless modified by remedial 
 agents, &c., almost certainly lead to the formation of renal or 
 vesical calculi. 
 
 Sediments consisting of urates are of more common occur- 
 rence than all other sediments collectively. Excepting urate 
 of ammonia, they occur solely in acid urine. Their colour 
 may vary from a greyish-white to a brownish-red or purple, 
 and is considerably affected by exposure to the atmosphere. 
 These might sometimes be mistaken at first sight for deposits 
 of blood or pus, but the application of the murexide test, or of 
 the microscope, or even of a gentle heat (which dissolves them, 
 
THE URINE. 359 
 
 but exerts no material change on the corpuscles of blood or 
 pus), will remove any doubt as to their true nature. 
 
 The chemical and microscopic characters of the urates 
 of soda, ammonia, and lime, are sufficiently given in p. 65. 
 
 The urate of soda is by far the most common of the urates ; 
 it occurs in most febrile affections, and in all conditions of the 
 system in which the due oxidation of the blood is not effected ; 
 the urate of ammonia is of much less frequent occurrence, and is 
 usually found in alkaline urine mixed with earthy phosphates ; 
 while urate of lime occurs very seldom, and only in small 
 quantity. 
 
 There are two perfectly distinct conditions of the urine, in 
 which we may have sediments of urates. 
 
 1. The daily or hourly amount of excreted uric acid may 
 exceed the normal quantity, in which case the presence of the 
 sediment must be referred to an increased formation of uric 
 acid in the organism, or, at all events, to an increased sepa- 
 ration of it by the kidneys. 
 
 2. Or if the urine be very scanty, and does not contain 
 enough water for the purpose of solution, we may have a 
 sediment without any augmentation of the daily or hourly 
 amount of uric acid. 
 
 Hence we must not conclude from the presence of a sedi- 
 ment of urates that there is of necessity an absolute augmen- 
 tation of uric acid. 
 
 We shall now endeavour to explain the causes which 
 usually occasion the formation of a sediment of urates. 
 
 The urates being much more soluble in hot than in cold 
 water, a urine nearly saturated with these salts will deposit 
 them as it gradually cools ; hence the reason why urine which 
 at the moment of its discharge is perfectly clear becomes 
 turbid on cooling. This, however, cannot explain the occa- 
 sional separation of the urates within the body ; and Vogel 
 suggests that such a separation may occasionally arise from 
 urine saturated at the moment of its secretion with urates, 
 
 A A 4 
 
360 PHYSIOLOGICAL CHEMISTRY. 
 
 becoming further concentrated in the bladder by a process of 
 endosmosis, and thus throwing down a portion of these salts in 
 an undissolved state. 
 
 Again, the neutral urates are more soluble than the acid 
 urates, and these again than free uric acid. Hence any con- 
 dition which converts the neutral into acid urates will occa- 
 sion a deposit, provided the urine be tolerably rich in uric 
 acid. We have already seen (see p. 355) how such an effect 
 as this may be produced externally to the body in the acid 
 fermentation, and the same may take place also within the 
 body, either by the establishment of acid fermentation within 
 the bladder (a circumstance probably of rare occurrence), or by 
 the addition of a strongly acid urine to a faintly acid or alka- 
 line urine, rich in neutral urates, pre-occupying the bladder. 
 
 " Sediments of the urates," says Vogel, " are of most 
 common occurrence in acute febrile diseases or in febrile 
 exacerbations of chronic diseases. Several predisposing causes 
 are almost always simultaneously present in these cases : a 
 diminution of the quantity of the urine, an absolute augmen- 
 tation of the uric acid, a strongly acid reaction, and an 
 abundance of pigment. The sediment in these cases usually 
 appears some time after the discharge of the urine, and its 
 deposition is occasioned partly by the cooling of the urine, and 
 partly by the incipient urinary fermentation and the decom- 
 position of the pigment. 
 
 " These sediments are important as indicating certain 
 deviations from the ordinary metamorphosis of tissue, which 
 are peculiar to most febrile diseases, namely, an increased 
 formation of uric acid and pigment, and a diminished secre- 
 tion of water by the kidneys. They are frequently regarded 
 as critical, and as their retention in the blood gives rise to 
 various evils, their free discharge from the circulating fluid 
 may sometimes be deserving of the now nearly exploded 
 epithet ; too often, however, the unchecked progress of the 
 disease shows that they have no critical significance. 
 
THE URINE. 361 
 
 "These sediments sometimes occur in perfectly healthy 
 persons, if the above-mentioned conditions are present, as, for 
 instance, after prolonged bodily exertion, too abundant and 
 too frequent meals, and copious perspiration, so as to diminish 
 the amount of urine." 
 
 Hippuric acid occasionally, although only rarely, occurs Hippuric 
 as a urinary sediment. Its crystals usually appear in the 
 form of rhombic prisms with pointed ends (see Plate III. fig. 
 1), but sometimes are acicular. They may possibly be con- 
 founded at first sight with crystals of uric acid, or of phos- 
 phate of ammonia and magnesia, but they are readily dis- 
 tinguished from the latter by their insolubility in hydrochloric 
 acid, and from the former by their not yielding the charac- 
 teristic murexide reaction. Sediments containing a mixture 
 of crystals of uric and hippuric acid sometimes occur, and 
 Vogel states that he has occasionally seen acicular crystals of 
 hippuric acid projecting like spikelets from larger crystals of 
 uric acid. The two acids may be separated by boiling the 
 mixed sediment in alcohol, which takes up the hippuric acid 
 (which again separates on cooling), and leaves the uric acid 
 undissolved. The necessary tests for this acid have been 
 already given in p. 57. 
 
 The causes giving rise to the separation of hippuric acid as 
 a sediment, are precisely the same as those which occasion the 
 deposition of the uric acid. 
 
 Sediments of hippuric acid may occur in healthy persons 
 after the free use of fruit containing benzoic acid or other 
 benzoyle compounds (as for instance greengages), or after the 
 ingestion (in any form) of benzoic or cinnamic acids.* In 
 
 * I may again direct attention to the remarkable fact already noticed in p. 
 305, regarding the origin of hippuric acid. Kiihne discovered that during 
 icterus no hippuric acid appeared in the urine after the administration of benzoic 
 acid or its alkaline salts, but merely unchanged benzoic acid. This is probably 
 due to no glycocholic acid (but merely taurocholic, or perhaps cholalic acid) 
 being then formed in the liver; and glycine, as we have seen (page 59), appears 
 necessary for the conversion of benzoic into hippuric acid. See a translation of 
 Kuhne's Memoir on Icterus in Beale's Archives of Medicine, vol. i. p. 342. 
 
362 PHYSIOLOGICAL CHEMISTRY. 
 
 disease they are sometimes undoubtedly due to morbid meta- 
 morphic action : they may occur whenever there is an excess 
 of this acid, as in the acid urine common in fever, in diabetes, 
 in chorea, &c. Thudichum noticed a sediment of this kind 
 in the case of a young lady suffering from colic. In the 
 present imperfect state of our knowledge we can draw no 
 diagnostic inference from the occurrence of a sediment of 
 hippuric acid. 
 
 We have already (see pp. 7 9) noticed the chemical and 
 microscopical characters of oxalate of lime (see Plate I. 
 figs. 1 and 2). We may add that the crystals are often 
 so small as not only to be usually invisible to the naked eye, 
 but to require a somewhat high ^magnifying power to elicit 
 their actual shape. Lehmann's statement (see p. 8) that it is 
 often found in urine that has stood for some time, when it 
 was not present in the perfectly fresh urine, is supported by 
 the fact that this salt is soluble to a considerable extent in 
 acid phosphate of soda, and we may occasionally employ the 
 knowledge of this fact serviceably, in searching for oxalate of 
 lime crystals ; for if we are examining a very acid urine, the 
 separation of the crystals is much 'facilitated by nearly sa- 
 turating the free acid. It is a good plan to allow the urine 
 to stand for some hours in a cylindrical glass, pointed or 
 much contracted at the bottom. On carefully decanting the 
 supernatant fluid the crystals (if there are any) will be found 
 in the last remaining drops. 
 
 If we wish to ascertain whether urine immediately on its 
 emission contains crystals of oxalate of lime, our only course 
 is to filter it ; and then carefully to examine with the mi- 
 croscope the washings of the moist filter, when if crystals of 
 oxalate of lime be present they may be detected among an 
 intermixture of epithelium, fibres of the filter, &c. 
 
 We have already (see p. 8) referred to the probable sources 
 of oxalic acid in the system. It may either be introduced 
 into the organism in the food, or as a medicine (although it 
 
THE URINE. 363 
 
 is very rarely used as a therapeutic agent), or it may be 
 formed within either the animal or the vegetable organism, as 
 a product of decomposition. The mode in which we can obtain 
 oxalic acid in the laboratory by the oxidation of uric acid, and 
 by the imperfect oxidation of sugar, starch, and compounds 
 of vegetable acids with alkalies (tartrate, acetate of potash and 
 soda), elucidate to a certain degree the changes which probably 
 accompany the formation of oxalic acid in the system. 
 
 There is some difficulty in understanding how a salt so 
 thoroughly insoluble in water as oxalate of lime, can make 
 its way through the walls of the renal capillaries and pass 
 into the urine. Various explanations have been attempted. 
 C. Schmidt assumes that oxalate of lime forms a soluble 
 compound with albumen ; that in this form it exists in the 
 blood and passes into the urine ; and, finally, that in the 
 urinary passages this compound is decomposed, and that the 
 liberated oxalate of lime then separates as a sediment. 
 Another explanation assumes that the oxalic acid, formed by 
 the decomposition of the tissues, does not combine with lime 
 till it has entered the urinary organs. A third (and perhaps 
 the best) explanation is afforded by the observations and 
 experiments of Kletzinsky, who remarked that oxalic acid and 
 lime when brought together in a state of extreme dilution, 
 require the lapse of a certain time before they unite to form 
 an insoluble oxalate.* 
 
 The importance of oxalate-of-lime sediments, in reference 
 
 * The following experiments bearing on this point were made by Klet- 
 zinsky. He added oxalate of ammonia to urine which had been strongly acidu- 
 lated with acetic acid. After passing this fluid through four filters, he observed 
 after a short interval a slight crystalline turbidity arising from the oxalate of 
 lime in the previously clear fluid. He likewise introduced some of the above- 
 mentioned fluid into an endosmometer closed with a piece of bladder which 
 dipped down into pure tepid water. In the course of ten hours he found crystals 
 of oxalate of lime in the water outside the bladder. The lime-salt and the 
 oxalate of ammonia had here obviously been diffused through the membrane 
 in a state of indifference to each other, and had only combined to form oxalate 
 of lime after their escape from the endosmometer. 
 
364 PHYSIOLOGICAL CHEMISTRY. 
 
 to diagnosis and medical treatment, varies very much according 
 to the conditions under which such sediment occurs. Vogel 
 arranges these conditions in the two following groups : 
 
 (1.) There are cases in which the urine continuously, for 
 weeks or even months, contains large quantities of oxalate 
 of lime. This is the condition to which the terms oxaluria 
 and oxalic diathesis have been applied by some writers. 
 There are two perfectly different dangers to be apprehended 
 in such cases. 
 
 (a.) A renal or vesical concretion of oxalate of lime (the 
 mulberry calculus) may be formed. 
 
 (6.) Bad consequences may result from the poisonous 
 action of the oxalic acid on tjie digestive organs and the 
 organism generally, especially on the heart and nervous 
 system.* Beneke attempts to explain the noxious action of 
 the oxalic acid chemically. He believes that it dissolves the 
 phosphate of lime and removes it from the system, and that 
 from the loss of phosphate of lime thus induced, there is a 
 diminution in the formation of organic cells in the various 
 organs. The ordinary causes of this excessive formation of 
 oxalic acid in the system, seem to be disturbances of the 
 respiratory functions, with diminished absorption of oxygen, 
 a too abundant use of sugar, and probably many other con- 
 ditions giving rise to derangements of the ordinary meta- 
 morphic action going on in the various tissues. 
 
 (2.) Again, there are cases of quite a different kind, in 
 which we either find mere traces of oxalate of lime in the 
 urine, or where its more abundant appearance is merely 
 transitory, as during various acute and chronic diseases. In 
 these cases there is comparatively little to fear. 
 
 Sediments of earthy phosphates almost always consist of 
 
 * The consequences arising from the accumulation of oxalic acid in the 
 blood are very well described in a paper by Dr. James Begbie, " On Stomach 
 and Nervous Disorder, as connected with the Oxalic Diathesis," in the Monthly 
 Journal of Medical Science, August, 1849. 
 
THE UKINE. 365 
 
 an admixture of phosphate of lime, and phosphate of am- Earthy 
 monia and magnesia. In consequence of their very ready 
 solubility even in very weak acids, they can never occur in a 
 urine presenting an acid reaction, and we only meet with 
 them in neutral or alkaline urine. 
 
 Phosphate of lime occurs in sediments, as an amorphous 
 powder insoluble in water, but soluble in acids, from which it 
 is again precipitated by alkalies. In normal urine it is held 
 in solution by the free acid. (In those cases in which it is 
 precipitated by heat, it had most probably been dissolved by 
 carbonic acid). 
 
 Phosphate of ammonia and magnesia is not a normal con- 
 stituent of the urine, but always appears in singularly beau- 
 tiful crystals as soon as that fluid becomes alkaline. In 
 certain grave forms of disease of the bladder, and of the 
 spinal cord, sediments consisting solely of these crystals are 
 often noticed, and Lehmann once saw a similar sediment in 
 a case of diabetes. (See Plate IV. fig. 5.) 
 
 These crystals of phosphate of ammonia and magnesia 
 may generally be at once recognised by these forms. They 
 most frequently present shapes which are modifications of 
 rhombic vertical prisms, and somewhat resemble, and have 
 been compared to coffins. They are insoluble even in hot 
 water, but dissolve readily in acetic acid, by which means they 
 may be distinguished (if necessary) from crystals of oxalate of 
 lime. They are not affected by alkalies. 
 
 Since the phosphates of lime and magnesia occur in normal 
 urine (see p. 321) in the ratio of two to one, we may conclude 
 that this is nearly the ratio in which these earthy sediments 
 are composed. 
 
 When the alkalinity of the urine is due to the administra- 
 tion of liquor potassse or of carbonate of potash or soda, and 
 not to the presence of carbonate of ammonia, the sediment 
 consists solely of phosphate of lime and magnesia, without any 
 crystals of triple phosphate. 
 
366 PHYSIOLOGICAL CHEMISTRY. 
 
 If the earthy phosphates are mixed with other sedimentary 
 matters, we may be assisted in their recognition by recollect- 
 ing; (1.) that urates are readily soluble in hot water, while 
 the phosphates are insoluble ; (2.) that acetic acid will enable 
 us to distinguish between phosphate of ammonia and magnesia, 
 and certain somewhat similar forms of oxalate of lime ; and (3.) 
 that free uric acid cannot occur in the neutral or usually 
 alkaline urine, which contains a sediment of earthy phosphates. 
 
 We have no right to infer from the presence of a sediment 
 of earthy phosphates, that these substances exist in excess in 
 the urine, for every .urine, when it becomes alkaline, throws 
 down such a sediment (see p. 356). We can only decide 
 whether there is an actual augmentation of the earthy phos- 
 phates by a quantitative analysis, of the urine with respect to 
 them ; but an easy method has been suggested by Beneke for 
 their approximate determination, the details of which are 
 given in the foot-note.* 
 
 Independently, however, of any quantitative analysis of 
 
 * By saturating the free acid of the ui-ine by any alkali, we obtain the pre- 
 cipitation of any earthy phosphates that may be contained in it ; and from the 
 amount of turbidity that ensues, we can approximately determine the amount 
 of the earthy phosphates. Beneke recommends that cylindrical test-tubes of the 
 same size, and having a mark or line indicating the half-ounce fluid measure, 
 together with a soda solution of known strength (one part of soda to twelve of 
 water) should be employed : and he uses a numerical scale, containing seven 
 magnitudes, to indicate seven different degrees of turbidity. 
 
 By he indicates a urine which exhibits no turbidity whatever after half an 
 ounce has been boiled in a test-tube, and five, ten, or fifteen drops of the soda- 
 solution have been added. 
 
 By |, a urine which when similarly treated exhibits a slight opalescence. 
 
 By 1, a urine which exhibits a strong opalescence, but is still sufficiently 
 transparent to allow us to see certain objects (as the bars of a window) through it. 
 
 By If, a more opalescent urine, through which objects can no longer be dis- 
 tinguished. 
 
 By 2, a urine which is strongly turbid more than opalescent. 
 
 By 2|, a urine which, a few seconds after the addition of the soda, yields a 
 considerable precipitate of earthy phosphates. 
 
 By 3, a urine which at once forms a copious precipitate. 
 
 By 3-4, a urine which throws down the largest possible quantity of earthy 
 phosphates on the addition of the soda. 
 
THE URINE. 367 
 
 the earthy phosphates, their mere presence often serves to 
 direct our attention to the fact that the urine is alkaline, and 
 in that respect is of diagnostic importance. Having ascer- 
 tained, either by this means or by ordinary test-paper, that 
 the urine is alkaline, we have to investigate the cause of that 
 abnormal reaction. 
 
 (1.) The alkaline reaction may be due to carbonate of Various 
 ammonia, which (unless in the comparatively rare cases in " 
 
 which that salt has been prescribed, and has passed directly reaction of 
 into the urine) always depends upon the decomposition of 
 urea, and is usually associated with blennorrhcea or pyorrhoea. 
 
 In this case red litmus-paper moistened in the urine 
 becomes blue, but regains its red colour on drying. 
 
 (2.) Or the alkaline reaction may depend on the presence 
 of a fixed base (potash or soda) or of an alkaline earth. The 
 cause of the reaction in these cases may be referred 
 
 (a.) To the medicinal use of the caustic alkalies, of the 
 alkaline earths, or of their carbonates, tartrates, acetates, &c. 
 
 (6.) Or to the use of food rich in some of these compounds 
 (certain fruits, for instance, as strawberries, &c.) 
 
 (c.) Or to certain modifications in the metamorphosis of 
 tissue. 
 
 In these cases red litmus-paper moistened in the urine 
 becomes blue, and remains so after drying. 
 
 With regard to the- practical value of the alkalinity of the 
 urine in relation to the prognosis and treatment of a case, 
 
 Beneke has ascertained by careful experiments that one fluid ounce of urine 
 
 of scale contains from 0' 10 to 0' 15 of a gramme of earthy phosphates. 
 
 | 0-25 0-30 
 
 1 0-40 0-45 
 
 1| 0-55 0-60 
 
 2 070 0-75 
 2| 0-85 090 
 
 3 I'OO 1-05 
 3-4 I'OO T30 
 
 Hence we can readily approximate to the daily excretion of the earthy 
 phosphates. 
 
368 PHYSIOLOGICAL CHEMISTRY. 
 
 Vogel remarks, that if the disappearance of the normal 
 acid reaction is only transitory ; if it only occurs at one 
 period of the day, as for instance some hours after the prin- 
 cipal meal, or after certain kinds of food, or only on oc- 
 casional days, the indication is rather of physiological than of 
 practical interest. If, on the other hand, the urine is fre- 
 quently or always alkaline, the indication is of great dia- 
 gnostic and practical value. If the urine is ammoniacal, and 
 contains pus or mucus and crystals of phosphate of ammonia 
 and magnesia, we diagnose a blennorrhcea or pyorrhoea of the 
 urinary passages. If it is alkaline without being ammoniacal, 
 and we cannot trace this condition to the use of medicines or 
 peculiarities of food, we must refer it to certain modifications 
 in the metamorphosis or disintegration of the tissues, regard- 
 ing which we have little definite knowledge, but which seem 
 especially to occur when there is imperfect metamorphosis of 
 the muscular tissue, want of tone in the nervous system, 
 anaemia, chlorosis, and imperfect nutrition, and under a 
 depressed condition generally.* 
 
 It would be altogether out of place here to enter into 
 details regarding the treatment in cases of alkaline urine ; 
 but it may be well to observe that the common practice of 
 (on false chemical grounds) prescribing acids often leads to 
 very bad results, as might, indeed, be foretold if we recollected 
 that the alkalinity of the urine is often primarily dependent 
 upon the irritation established by too acid an urine on the 
 delicate mucous structures with which it comes in contact. 
 
 When the urine on its emission contains a sediment of 
 earthy phosphates, these salts must obviously have been 
 separated within the urinary cavities, and if this phenomenon 
 
 * Rademacher, the author of an ingenious but vague system of medicine, 
 remarked that ferruginous preparations were the proper remedies for cases of 
 constantly alkaline urine. Vogel remarks, that this statement requires some 
 limitation. Pale urine is a much more certain indication that iron is required, 
 and, as has been already mentioned, urine with little pigment has a great ten- 
 dency to become alkaline. 
 
THE UEINE. 369 
 
 should continue for any length of time, the formation of a 
 concretion in the kidney or bladder would probably result. 
 
 Cystine occasionally, but very rarely, forms a urinary sedi- Cystine. 
 ment. It may be readily separated from an admixture of 
 urates and of the earthy phosphates by boiling, and by the 
 addition of acetic acid, which dissolve everything but the 
 cystine. Its microscopical and chemical tests are sufficiently 
 given in page 51. 
 
 An interesting notice of cystine-formation has recently been 
 recorded by ToeL* Two otherwise healthy sisters (except 
 that they had occasional pain in the region of the kidneys, 
 due, probably, to a renal calculus of cystine) passed urine 
 containing a sediment of cystine. This sediment was most 
 abundant in the morning urine f, and the total excretion 
 averaged more than a scruple daily. There is reason to 
 believe that the formation of cystine is occasionally an here- 
 ditary peculiarity. 
 
 The probable origin of cystine is sufficiently noticed in 
 page 52. In the present imperfect state of our knowledge 
 we can draw no diagnostic inferences from its presence, except 
 that there is possibly a cystine-concretion in the kidney or 
 bladder. 
 
 Xanthine and guanine may possibly occasionally be con- 
 stituents of urinary sediments. As far as I know there are, 
 however, no recorded cases of their thus occurring. 
 
 We now come to the consideration of the organised sedi- 
 ments. 
 
 Every urine contains more or less mucus, which is derived Mucus and 
 from the mucous membrane of the uropoietic viscera, and 
 which, when the urine is allowed to stand, soon falls down 
 in the form of a cloudy sediment. : On examining such a 
 
 * Ann. d. Ch. u. Pharm. vol. xlvi. p. 247. 
 
 f The same was observed in a specimen of urine containing cystine analysed 
 by Dr. Beale. See Archives of Medicine, vol. i. p. 136. 
 
 J I have previously alluded to the part which mucus plays in causing the 
 
 B B 
 
370 PHYSIOLOGICAL CHEMISTKY. 
 
 sediment under the microscope we usually find distinct 
 nucleated epithelial cells, derived from the walls of the 
 bladder, and round, more or less granular, mucus-corpuscles 
 (cytoid corpuscles). 
 
 It must be recollected that pus-corpuscles maybe converted 
 in ammoniacal urine into a gelatinous magma, which very 
 closely resembles a mucous sediment. 
 
 The diagnostic indications of an excess of mucus are too 
 obvious to require notice. 
 
 Pus. Pus can only be recognised with certainty by the micro- 
 
 scope, under which (with a sufficient magnifying power, of 
 about 250 diameters) its corpuscles are seen as round, pale, 
 faintly granular bodies of varying sizes, which become trans- 
 parent on the addition of dilute acetic acid, and then dis- 
 tinctly reveal a very characteristic nucleus, which was 
 previously much less apparent. (See p. 390.) Their dis- 
 tinctly granular appearance, and their behaviour with acetic 
 acid, serve to distinguish them from blood-corpuscles. 
 
 Any considerable quantity of pus in urine always forms a 
 sediment. When it is only sparingly present, the urine must 
 be allowed to stand for some hours in a tolerably long test- 
 tube, and the last drops, after careful decanting, must be 
 placed under the microscope. The effect of ammoniacal 
 urine, to which we have previously alluded, must not be for- 
 gotten in the search for pus ; for in the gelatinous magma, 
 to which we have there referred, the shape and outlines of 
 the pus- corpuscles entirely disappear. Every purulent 
 urine is of course more or less albuminous, from the occur- 
 rence of the serum of the pus. 
 
 The presence of pus in the urine is always an indication of 
 suppuration of some part of the uropoietic viscera, or of an 
 
 decomposition of the urea : Scherer has demonstrated the correctness of this 
 view by removing the mucns from fresh urine, either by nitration or by the 
 addition of alcohol ; the urine then retains its acidity for a very much longer 
 time than ordinary. 
 
THE URINE. 371 
 
 abscess communicating with them,, except when (in women) 
 it sometimes makes its way into the urine from the vagina or 
 uterus. 
 
 It is often by no means easy to determine the seat of sup- 
 puration. Vogel remarks that when the pus arises from the 
 urethra, pus is usually discharged at other times than those 
 of micturition ; if it arises from the bladder there are usually 
 certain symptoms (local pain, &c.) indicative of disease of 
 that viscus ; if it arises from one or both ureters, colic-like 
 pains are felt in the region of those ducts, while suppuration 
 of the parenchymatous structure of the kidney is often accom- 
 panied with little or no local disturbance. We are further 
 assisted in deciding whether pus arises from a mere superficial 
 inflammation of the mucous membrane or from deeper seated 
 disease, by recollecting that if the appearance of pus in the 
 urine is transitory lasting only for a few days the pus is 
 probably only the result of a superficial inflammation, while, if 
 it is persistent, it probably originates in a deeper source ; and 
 by the appearance, under the microscope, of the corpuscles : 
 for pus, from a superficial source, presents the corpuscles in 
 their normal (perfectly spherical) form, and with clearly de- 
 fined characteristic nuclei (as shown by the addition of acetic 
 acid) while in deeper seated suppuration there are'often various 
 deviations from the normal type, both the corpuscles and 
 their nuclei presenting more or less want of definite character. 
 
 Cancerous and tubercular matters sometimes occur in the Cancerous 
 urine, and their detection is obviously of great diagnostic " 
 
 importance to the physician, as indicating that a cancerous matters. 
 or tuberculous deposit, in some portion of the uropoietic 
 viscera is in the stage of softening and disintegration. 
 
 When cancer-cells occur in the urine they much more 
 commonly arise from cancer of the bladder than from cancer of 
 the kidneys. The cancer is usually the soft or medullary 
 kind, and the cells found in the urine generally occur aggre- 
 gated in small masses, presenting the various modifications 
 
 B B 2 
 
372 PHYSIOLOGICAL CHEMISTRY. 
 
 of form and shape which are found in cancerous forma- 
 tions.* 
 
 Tubercular matter, when it occurs in the urine, closely 
 resembles pus, from which it cannot be distinguished without 
 the aid of the microscope. It consists of irregular and im- 
 perfectly developed pus-corpuscles, fragments of cells, de- 
 tached nuclei, and an indistinct finely granular matter, in 
 which broken crystals of cholesterin may sometimes be 
 detected. In these cases the tubercular matter is deposited 
 in the mucous or submucous tissue of some portion of the 
 urinary tract. 
 
 Tubular In certain forms of disease affecting the parenchyma of the 
 
 casts. kidneys, peculiar, elongated, tubular, or cylindrical bodies 
 
 are observed on instituting a microscopic examination of the 
 sediment. They mainly occur in the three following forms : 
 (1.) Epithelial tubes. These are tubular aggregations of 
 epithelial cells, precisely like those which we obtain from the 
 medullary portion of a fresh kidney, and consist of the epi- 
 thelium of the uriniferous tubes (the tubes of Bellini), which 
 is detached in patches by a morbid process, and is thus dis- 
 charged with the urine. Together with these larger tubes, 
 we often find cylindrical epithelium from the calyces, or the 
 pelvis of the kidney, and occasionally pus-corpuscles. 
 
 (2.) Granular cylinders. These are solid, granular, cylin- 
 drical masses, similar in form and size to the first variety. 
 We can sometimes see detached epithelial cells, blood- 
 globules, pus- corpuscles, or oxalate-of-lime crystals in their 
 interior. - 
 
 (3.) Hyaline cylinders. These, like the preceding, are 
 solid cylinders, but so pale and transparent that it requires 
 considerable tact to distinguish them, under the microscope, 
 from the surrounding fluid. They may be rendered more 
 distinct by adding to the urine a few drops of a solution of 
 iodine in iodide of potassium, which gives them a brownish tint. 
 
 * See Vogel's Pathological Anatomy (translated by the author of this work) 
 for the best account of the Histology of Cancerous Formations. 
 
THE URINE. 373 
 
 Since these tubes and cylinders often occur only in small 
 number, we must, if we wish to determine whether any are 
 present, adopt one of the two following courses : we must 
 either allow the urine to stand for a considerable time, and 
 then examine the sediment, or else we must filter it, and ex- 
 amine the contents of the filter. In doubtful cases the 
 iodine solution should be added so as just to colour the urine. 
 Structures are occasionally found in urinary sediments, which 
 may easily be mistaken for granular cylinders, but which 
 seem to be aggregations of molecular particles in a cylindrical 
 form : they occur, for the most part, in albuminous urine, or 
 in urine which has stood till decomposition had commenced, 
 and are apparently composed of albumen, and possibly mucus, 
 precipitated in a finely granular state. They have a less 
 regular form than the true granular cylinders. 
 
 The detection of these tubes and cylinders is of great dia- 
 gnostic importance, since they always originate from the 
 tubular structure of the medullary portion of the kidney (the 
 tubes of Bellini), and indicate that certain morbid processes 
 are going on there. They are sometimes regarded by in- 
 expert pathologists as a certain sign of Bright's disease, but 
 Blight's disease is no longer associated with a single morbid 
 condition of the kidney ; and farther, the epithelial tubes and 
 the granular and hyaline cylinders indicate the presence of 
 very different processes in that organ. 
 
 The presence of epithelial tubes in the urine shows that the 
 epithelium is peeling away from the tubes of Bellini in short, 
 that there is desquamative nephritis, a process which may 
 disappear in a few days, without leaving any bad consequences. 
 When, however, pus-corpuscles are intermingled with the 
 epithelial tubes, we may infer that there is more or less in- 
 tense inflammation of the renal structures. These tubes are 
 most commonly observed in the beginning of granular de- 
 generation of the kidney, and in the desquamative stage of 
 erysipelas and scarlatina* 
 
 BBS 
 
374 PHYSIOLOGICAL CHEMISTRY. 
 
 The granular and hyaline cylinders are indications of a 
 more serious, and a chronic affection of the parenchymatous 
 structure of the kidney. The hyaline cylinders are probably 
 formed by an exudation and subsequent coagulation of a 
 fibrinous fluid upon the inner surface of the tubes ; in short, 
 by a croupous exudation; while the granular cylinders are 
 formed, either by a subsequent metamorphosis of the fibrinous 
 effusion, or by the degeneration of the glandular epithelium 
 which lines the uriniferous tubes. 
 
 The number and persistence of these structures in the urine 
 are usually proportional to the severity of the morbid 
 process. 
 
 When the cylinders contain much fatty matter (and both 
 fat-globules and fatty granules afe often enclosed in them), 
 we may infer that the morbid process going on in the kidney 
 is fatty degeneration. 
 
 If blood-globules are frequently contained in the cylinders, 
 or if blood is mixed with them, we may infer the presence of 
 fatty or lardaceous degeneration of the minute vessels form- 
 ing the Malpighian bodies* 
 
 If the cylinders present either a very small or a very large 
 diameter, we infer in the former case a contraction, and iri 
 the latter a dilatation of the uriniferous tubes ; while if the 
 cylinders deviate from their normal form, and present constric- 
 tions and dilatations, we may infer that the tubes in which 
 they were formed are in a varicose state. 
 
 Fungi. Fungi, not unlike the Mykoderma cerevisice in shape, but 
 
 considerably smaller (-^-J-oth to ^-Q-th of a line), commonly 
 occur in stale urine ; and sometimes, viz., when in cases of 
 vesical catarrh, the urine has undergone incipient decomposi- 
 tion before emission, they may be detected in the freshly dis- 
 charged fluid. Their presence is of no special diagnostic im- 
 portance if we except the yeast-plant (Myk. cerev.), which in 
 a tolerably warm atmosphere is always developed spon- 
 taneously in diabetic urine. (See Plate V. fig. 1.) 
 
THE URINE. 375 
 
 I am not aware of any cases in which Infusoria have been Infusoria, 
 detected in perfectly fresh urine, although monads and 
 vibriones are sometimes developed in an extremely short time, 
 indicating a great depression of the vital powers, and a septic 
 condition of the organism. Dr. Hassall has recently described 
 the occurrence of an infusorium of the genus Bodo, in the 
 urine ; and Groodsir's Sarcina ventriculi * has been observed 
 in a few cases. 
 
 Spermatozoa sometimes occur in the urine from obvious Sperma- 
 and natural causes. They are stated to have been detected l 
 in the urine in cases of typhus, and Lambl has suggested that 
 the presence of a catheter as it passes the prostate, especially 
 if a digital examination per anum is being simultaneously 
 made, may cause their appearance in the urine. 
 
 (294.) The following general resume of the preceding re- Tabular 
 marks on the urinary sediments may serve to facilitate the 
 microscopic recognition of the individual varieties. 
 
 A. The urine acid. 
 
 (1.) The sediment entirely amorphous* We warm a drop 
 or two on an object-glass. 
 
 (a.) If, as is probable, there is perfect solution, the sedi- 
 ment consists of urates (almost certainly acid urate of soda.) 
 If we add a drop of acetic or hydrochloric acid, rhombic 
 tablets of uric acid soon appear. (See Plate III. fig. 4.) 
 
 (6.) If glistening, strongly refracting globules are inter- 
 mingled with the sediment, and they are found to be soluble 
 in ether, they consist of fat. 
 
 (2.) The sediment partly or entirely crystalline. 
 
 (a.} Minute glistening perfectly transparent octohedral 
 crystals, presenting much the appearance of the front of a 
 letter envelope, and insoluble in acetic acid, are oxalate of 
 lime. (They sometimes require a magnifying power of 300 
 or 400 diameters.) (See Plate I. fig. L) 
 
 * Welctcer suggests that the sarcina found in the urine is a distinct species 
 from that found in the stomach. 
 
 B D 4 
 
376 PHYSIOLOGICAL CHEMISTRY. 
 
 (b.) Four-sided tablets, which by the rounding off of their 
 oblique angles sometimes present fusiform or barrel-like shapes, 
 and which are always more or less coloured, are uric acid. 
 If there is any doubt, we dissolve the crystals in a little 
 potash or soda solution, and add a drop of hydrochloric acid, 
 when we are sure to get sufficiently characteristic forms. 
 (See Plate III. fig. 4.) 
 
 (c.) Eegular hexagonal plates, which are soluble in hydro- 
 chloric acid (from which they are again precipitated by car- 
 bonate of ammonia), and soluble in ammonia (from which 
 they are again precipitated by acetic acid), are cystine. (See 
 Plate II. fig. 7.) 
 
 (3.) The sediment containing organised bodies. 
 
 (a.) Twisted bands consisting of series of rows of the most 
 minute granules are coagula of mucus, often accompanied 
 with urate of soda. They must not be confounded with the 
 cylinders described in pp. 372-4. 
 
 (b.) Small granular corpuscles, which are generally grouped 
 together into shield-like masses, are mucus-corpuscles. 
 
 (c.) Circular, slightly biconcave discs, usually of a faintly 
 yellow colour, which at once swell and after a short time 
 dissolve in acetic acid, leaving no nucleus, are blood-cor- 
 puscles. If they have been for any length of time exposed 
 to the action of the surrounding fluid, they are often angular, 
 jagged, and irregular. 
 
 (d.) Pale, granular, spherical globules of various sizes, 
 which swell and become transparent in acetic acid, and then 
 reveal distinct and characteristic nuclei, are pus-corpuscles. 
 
 (e.) Tubular cylinders can only be the casts described in 
 pp. 372-4. 
 
 (/.) Epithelial cells, varying according to their origin. 
 (aa). If they are roundish, elongated, or polygonal cells, with 
 tolerably distinct nuclei, they come from the bladder, (bb.) 
 If they are club-shaped and fusiform caudate cells, they come 
 from the ureters or the kidney. 
 
 (</.) Minute fungi generally occur in urine in which acid 
 
THE URINE. 377 
 
 fermentation is commencing. They commonly appear as 
 minute nucleated cells, which increase by gemmation, and 
 thus form single or branching rows. Other forms are some- 
 times seen. 
 
 (A.) Short thin rods wriggling through the fluid are vibriones. 
 (They are far less common in acid than in alkaline urine.) 
 
 (i.) The Sarcina ventriculi (of very rare occurrence in the 
 urine) cannot be mistaken for anything else. 
 
 (&.) Spermatozoa are recognised by their tadpole-like shape. 
 For their detection we require a somewhat high power. 
 
 (1.) Cancerous and tubercular matters (see p. 371). 
 
 B. The urine alkaline. 
 
 The sediment containing crystals. 
 
 (a.) If there are various combinations of rhombic vertical 
 prisms, which are soluble in acetic acid, and which, on being 
 warmed with a solution of soda, develope ammonia, they are 
 phosphate of ammonia and magnesia. Their peculiar micro- 
 scopic form is generally quite sufficient for their recognition, 
 without even the addition of acetic acid. See Plate IV. 
 
 fiff- 6. 
 
 If oxalate of lime is simultaneously present, it is brought 
 clearly into view by the addition of a drop of acetic acid. 
 
 (6). Small dark spherical masses studded with minute 
 projecting acicular crystals, are urate of ammonia. (See Plate 
 III. fig. 6.) 
 
 The sediment containing amorphous matter. 
 
 In an alkaline or a neutral urine this is almost certainly 
 phosphate of lime, in which case a drop of hydrochloric acid 
 will dissolve it. 
 
 The sediment containing organised bodies. 
 
 The same bodies occur here as in acid urine, but this is the 
 more natural habitat for fungi and infusoria. 
 
 (295.) Urinary concretions may be formed either in the Urinary 
 kidney or in the bladder, and are almost always the result of 
 the deposition and retention of a urinary sediment in some 
 portion of the uropoietic tract. Around the nucleus thus 
 
378 PHYSIOLOaiCAL CHEMISTRY. 
 
 formed additional matter is gradually deposited, till at length 
 the concretion may attain an enormous size. * 
 
 In consequence of the serious and often perilous disturbance 
 established in the system by the presence of a urinary 
 calculus, it is of great importance that we should not only be 
 able to detect, at a very early stage, the existence of such a 
 concretion, but also that we should be able to ascertain its 
 chemical composition; for with a knowledge of the latter 
 point, we can at all events usually prevent its further enlarge- 
 ment, although we have hitherto been seldom successful in 
 effecting the solution of an existing calculus within the 
 bladder. 
 
 Their The chemical constituents of urinary calculi are essentially 
 
 ents? 11 the same as those of the urinary sediments which have been 
 already described, namely : 
 
 Uric acid and urates, 
 
 Xanthine, 
 
 Cystine, 
 
 Oxalate of lime, 
 
 Carbonate of lime, 
 
 Phosphate of lime, 
 
 Phosphate of magnesia and ammonia, 
 
 Protein-compounds (fibrin, mucus), 
 
 Urostealith, 
 
 with occasional traces of silica, alumina, &c. 
 
 Many concretions consist solely of one of the above con- 
 stituents (especially of uric acid and of oxalate of lime) whilst 
 several constituents enter into the composition of others ; in 
 the latter case the different constituents usually occur in strata 
 or layers. 
 
 To ascertain the true nature of a calculus we must saw it 
 through the centre ; the section at once shows us whether the 
 external parts are identical with, or differ from the central 
 portion or nucleus. If the calculus is built up of various 
 
THE URINE. 379 
 
 strata, a portion of the powder of each stratum must" be 
 analysed. 
 
 (1.) If the portion of the concretion which we examine is Com- 
 entirely combustible, when exposed in a platinum spoon, or calculi!" 
 on a piece of platinum foil, to the heat of a spirit-lamp, or if 
 it merely leaves a very slight residue, it must consist of one 
 or more of the following substances : 
 
 Uric acid or urate of ammonia, 
 
 Xan thine, 
 
 Cystine, 
 
 A protein-substance, or 
 
 Urostealith. 
 
 In order to determine of which of the above substances the 
 pulverised concretion consists, we proceed as follows : 
 
 We first test for uric acid. If with nitric acid and ammonia Uric acid, 
 we obtain a distinct murexide-reaction (see p. 65), the con- 
 cretion consists either of uric acid or urate of ammonia. The 
 latter may be distinguished from the former by its much 
 greater solubility in boiling water, from which it again pre- 
 cipitates on cooling, and by its developing ammonia on the 
 addition of a solution of potash or soda. Of the two, uric 
 acid calculi are by far the more common. Indeed, they are 
 the most common variety of calculi. They frequently attain 
 a considerable size; are generally of a yellow, reddish, or 
 reddish-brown colour (seldom white), usually present a smooth 
 surface, and are tolerably hard in their consistence. Calculi 
 formed of urate of ammonia, are rare and generally only 
 small ; they are also of a lighter colour and a more earthy 
 consistence than uric acid calculi. 
 
 If the concretion is combustible and does not yield the 
 murexide-reaction, it must consist of xanthine, cystine, a 
 protein-substance, or urostealith. 
 
 Xanthine (or xanthic oxide) dissolves in nitric acid without Xanthine. 
 any evolution qf gas, and, after evaporation, leaves a bright 
 
380 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Cystine. 
 
 Fibrinous 
 calculi. 
 
 Urostea- 
 lith. 
 
 lemon-coloured residue, which is not reddened by ammonia, 
 but dissolves with a deep reddish-yellow colour in potash- 
 solution. 
 
 Calculi of xanthine are extremely rare, only three authen- 
 ticated cases having been placed on record as occurring in 
 man. They are of a light brown cinnamon colour, tolerably 
 hard, assume a waxy appearance when rubbed, and usually 
 consist of concentric, easily detachable layers. 
 
 Cystine calculi are by no means common, although not 
 nearly so rare as the preceding variety. They are of a dull 
 yellow colour, have a smooth surface, and when broken pre- 
 sent a glistening conchoidal fracture. They are soft enough 
 to admit of being readily scraped, and their powder communi- 
 cates a soapy feeling to the fingers. 
 
 In addition to the chemico-microscopical tests for cystine, 
 mentioned in p. 51, we may notice the following test pro- 
 posed by Liebig, which is based on its large percentage of 
 sulphur. 
 
 If a calculus, containing cystine, be dissolved in potash- 
 solution, and if a little solution of acetate of lead be added, 
 and the mixture boiled, a black precipitate of sulphide of 
 lead is formed, which gives to the fluid the appearance of 
 ink. 
 
 Calculi, consisting of protein-substances (fibrin or coagu- 
 lated blood), are very rare. They present no signs of crystal- 
 lisation, evolve on combustion an odour of burned horn, are 
 insoluble in water, ether, and alcohol, but dissolve in potash- 
 solution from which they are precipitable by acids ; they are 
 also soluble in boiling nitric acid. 
 
 Calculi of urostealith * have only been observed in three 
 
 * For further particulars regarding this very rare form of urinary concretion 
 I may refer to my translation of Simon's Animal Chemistry, vol. ii. pp. 326 
 and 4.52, in which I have given a full abstract of the views of Heller, its dis- 
 coverer. Dr. W. Moore has subsequently published a notice of two cases in 
 the Dublin Quarterly Journal of Medical Science, for March 1854* vol. xvii. 
 p. 473 ; and another seems recently to have occurred in the practice of Pro- 
 
THE URINE. 381 
 
 i 
 
 or four cases. In their fresh state they are soft and elastic, 
 and feel to the hand like india-rabher. When dried they con- 
 tract, become darker in colour, and hard, but again soften on 
 warming. On heating a fragment on platinum foil, it fuses 
 and swells up, and gives off a pungent odour, resembling that 
 of shellac and benzoine ; it then takes fire, and burns with a 
 clear yellow flame, leaving a voluminous carbonaceous residue. 
 It dissolves with difficulty in hot alcohol, but readily in ether. 
 Its elementary composition is entirely unknown ; but it is ap- 
 parently a resin or a fat. 
 
 (2.) If the concretion is incombustible or leaves a con- Incom- 
 siderable residue after exposure to a strong heat, it may ^^ 
 consist of 
 
 Urates with a fixed base (soda, magnesia, lime). 
 
 Oxalate of lime. 
 
 Carbonate of lime. 
 
 Phosphate of lime, or 
 
 Phosphate of magnesia and ammonia. 
 
 The urates of soda, magnesia, and lime never, either alone The urates. 
 or in association with one another, are the sole or even 
 principal constituents of a urinary calculus, but they some- 
 times occur in various quantities in calculi consisting mainly 
 of uric acid or urate of ammonia. 
 
 To ascertain whether these bases are present in combina- 
 
 fessor Santesson of Stockholm, whose " Cases in Surgical Practice," have lately 
 (August 24th, 1859) been translated by Dr. Moore for " The Dublin Medical 
 Press." Neither Professor Santesson nor the chemist who examines the calculi 
 in question seems to have heard of urostealith. They describe the nucleus as 
 consisting of " a fat which was its chief constituent, in combination with some 
 lime," and believe that it has arisen from the metamorphosis of coagulated 
 blood. I agree with Dr. Moore in thinking that the nucleus was Heller's uro- 
 stealith, and it is not improbable that their suggestion regarding its origin is 
 correct. Many years ago my friend, Dr. Henry Bennet, brought me a small 
 oval mass of a yellow colour and tolerably soft consistence, which was passed 
 from the bladder of a female patient of his ; and which I strongly suspect was 
 the substance in question. 
 
382 PHYSIOLOGICAL CHEMISTRY. 
 
 tion with uric acid, we boil a portion of the powdered calculus 
 and filter while hot ; on evaporation we obtain these urates 
 if they are present, and by incinerating the residue thus left, 
 we obtain the fixed bases. If they render moistened turmeric 
 paper brown, potash or soda must be present, and the latter 
 may be identified by the yellow tinge which it gives to the flame 
 of the blow-pipe. Unless the heating has been much prolonged, 
 the magnesia and lime will occur in the ash as carbonates, 
 which are insoluble in water, but dissolve freely in dilute 
 acids, from which they may be precipitated as phosphate of 
 magnesia and ammonia, and as phosphate of lime, by an 
 addition of phosphate of soda, and of ammonia. 
 
 Oxalate of Oxalate of lime blackens on exposure to a strong heat, in 
 consequence of the charring of .its organic matter (mucus), 
 but by prolonged exposure to heat it becomes white, without 
 fusing. By strong and prolonged heat it is reduced to 
 caustic lime, which communicates a brown tint to moistened 
 turmeric paper ; when exposed to a less amount of heat it is 
 only reduced to carbonate of lime, which dissolves with 
 effervescence in dilute hydrochloric acid. On neutralising 
 this solution with ammonia we obtain no precipitate, but by 
 the farther addition of oxalic acid, or by at once adding 
 oxalate of ammonia, oxalate of lime is again precipitated, 
 which, if we wish to carry our tests farther, is found to be 
 insoluble in boiling water, in acetic acid, and in potash solu- 
 tion, but to dissolve in hydrochloric or nitric acid without 
 effervescence. 
 
 Calculi of oxalate of lime are not uncommon, especially 
 in children. They are sometimes small, of a pale colour, and 
 smooth, when they are known as hemp-seed concretions ; 
 while more commonly they are larger, of a darker colour, 
 rough, and even nodular, when they are known as mulberry 
 calculi. 
 
 Carbonate Calculi composed solely or mainly of carbonate of lime 
 of lime. are rare j n fo e numan subject, but common in herbivorous 
 
THE URINE. 383 
 
 animals. In the few cases in which they occur they have 
 been generally found to be small and numerous, and to pre- 
 sent a whitish chalk-like character. Carbonate of lime is 
 often found in comparatively small quantity in calculi con- 
 sisting chiefly of oxalate of lime or earthy phosphates. 
 
 Concretions of carbonate of lime blacken upon exposure to 
 a strong heat, in consequence of the mucus, &c., which is 
 usually contained in them, but subsequently become white. 
 The remarks made on the chemistry of oxalate of lime afford 
 the necessary information for the recognition of carbonate of 
 lime. 
 
 Phosphate of magnesia and ammonia, and basic phosphate Fusible 
 of lime usually occur together in urinary calculi, which have 
 originated from the urine becoming ammoniacal within the 
 bladder. They often attain a considerable size, usually have 
 a whitish colour, and are soft, porous, and chalky, when the 
 phosphate of magnesia and ammonia preponderates, and are 
 comparatively hard and dense when the phosphate of lime is 
 in excess. 
 
 When exposed to a strong heat they become fused into a 
 white enamel-like mass, and from this characteristic property 
 they have received the name of fusible calculi. Moreover, 
 no amount of heat will render their reaction alkaline, which 
 likewises serves to distinguish them from oxalate and carbo- 
 nate of lime. They are soluble in hydrochloric acid without 
 effervescence, both before and after exposure to heat, and, in 
 the latter case, the solution is precipitated by ammonia. 
 
 If we wish to separate the two phosphates from one 
 another we must dissolve the powdered fused mass in dilute 
 hydrochloric acid and filter. We must then add ammonia to 
 the filtrate till only a faintly acid reaction remains, or, if we 
 add too much ammonia, so as to render the solution neutral 
 or alkaline, and consequently turbid, we must dissolve the 
 precipitate by the addition of a few drops of acetic acid. If 
 we now add oxalate of ammonia, the lime (alone) is preci- 
 
384 PHYSIOLOGICAL CHEMISTRY. 
 
 pitated as an oxalate, while the phosphate of magnesia and 
 ammonia remains in solution. To obtain the latter salt we 
 must remove the lime by nitration, and then supersaturate 
 with ammonia. 
 
 The above-named ingredients of calculi often occur in 
 various combinations ; thus we sometimes find earthy phos- 
 phates associated with uric acid and urates, and sometimes 
 with oxalate of lime ; and calculi have been analysed which 
 contain no less than six different ingredients, viz. : uric acid, 
 urate of ammonia, oxalate of lime, phosphate of lime, car- 
 bonate of lime, and phosphate of magnesia and ammonia. 
 The various constituents are sometimes intimately inter- 
 mingled with one another, and sometimes deposited in 
 separate and distinct strata ; in. the latter case having been 
 obviously deposited at different times, in consequence of a 
 change having occurred (often from the administration of 
 alkalies or their carbonates) in the acidity or composition of 
 the urine. If, for instance, in a case of the so-called uric 
 acid diathesis, the urine is sometimes strongly acid, so as to 
 decompose the urates, and then for a time less acid, or even 
 neutral, so that undecomposed urates are deposited, we have 
 the necessary conditions for a calculus with alternate layers of 
 uric acid and urates ; and the earthy phosphates, which so 
 often form an outer coating to a mulberry calculus, owe their 
 origin to urine having become ammoniacal from the irritation 
 set up in the bladder by the stone. 
 
385 
 
 CHAPTER XV. 
 EXUDATIONS PUS. 
 
 (296.) EXUDATIONS in many respects resemble the transuda- Character- 
 tions described in CHAP. XI. Sect, iv., and the two classes of exudations 
 fluids have not been sufficiently separated by some writers on 
 Pathology. As we shall shortly see, they essentially differ 
 from one another in their origin, in the mode in which they 
 are separated from the blood, and in their physical and 
 chemical properties. 
 
 The formation of transudations is dependent on simple Difference 
 physiological laws (see p. 258). In transudations certain con- 
 stituents of the blood-plasma permeate the walls of the capil- tions 
 laries, partly in consequence of increased penetrability of 
 these walls, and partly in consequence of the plasma having 
 an increased diffusion-power, and we have no actual stasis 
 of the blood in the capillaries; while exudations arise as a 
 consequence of inflammation (of a perfect stasis of the blood 
 in the capillaries) and partial rupture of the vessels. 
 
 In exudations we always find very, considerable quantities and exu- 
 of fibrin, and far more albumen than in transudations, the c 
 phosphates and potassium-compounds are also in excess in 
 the former, and blood-corpuscles (more or less modified in 
 form) are also present, which is never the case in true transu- 
 dations. But the principal point of difference between the 
 two is that the former have a great capacity for undergoing 
 further changes, and for developing cells and tissues, while 
 the latter will remain almost entirely unchanged for a great 
 length of time in the cavities in which they were originally 
 effused. The substances, whose presence in exudations gives 
 
 c c 
 
386 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Cause of 
 their plas- 
 ticity. 
 
 rise to their plasticity, and whose absence from transudations 
 seems to deprive the latter fluids of this property, probably are 
 fibrin, phosphates, and the hsematocrystallin which passes 
 into the exudations with the blood-corpuscles. 
 
 The commonly received view that the plasticity of the 
 exudations is essentially dependent on their fibrin, is strongly 
 opposed by the fact that in certain transudations (as, for 
 instance, in acute dropsy) there is an abundance of fibrin, 
 and yet no morphotic elements are produced ; and we are 
 hence led to suspect that this plasticity must be in some way 
 connected with the escaped contents of the destroyed blood- 
 corpuscles. The phosphates again probably assist in con- 
 ferring this property on exudations, for we universally find 
 (even in the lower animals, whose organisms are relatively 
 poor in such salts) that, wherever cells and fibres are formed, 
 phosphates are accumulated in appreciable quantity ; and it 
 has likewise been ascertained that the blood returning from 
 organs remarkable for the activity of their metamorphoses 
 (as, for instance, the muscles) contains far less phosphates than 
 the corresponding blood returning from organs which exhibit 
 a less amount of vitaj activity* ; moreover careful analyses 
 have proved that even in the plastic secretions from wounds 
 there is a larger proportion of phosphates than in the cor- 
 responding liquor sanguinis (see p. 387). These facts seem 
 to warrant the view that the presence of phosphates is neces- 
 sary for the formation of cells and tissues, although they by 
 no means entitle us to hold that plasticity is due to them 
 alone. 
 
 Different (297.) In morbid anatomy we recognise (with Rokitansky) 
 
 exudations. tnree leading forms of exudation, viz. (1) fibrinous 
 
 exudation, which is again divisible into the simple (or plastic), 
 
 the croupous, and the tuberculous varieties ; (2) albuminous 
 
 exudation ; and (3) purulent exudation. 
 
 * Lehmaun's Physiological Chemistry, vol. iii. p. 137. 
 
EXUDATIONS. PUS. 387 
 
 Chemical investigation has as yet only been satisfactorily 
 made of fibrinous plastic exudations, and of purulent exuda- 
 tions or pus. 
 
 The fibrinous plastic exudation is the only one which can Fibrinous 
 be easily obtained in a perfectly fresh and tolerably pure exudation, 
 state. Fresh wounds afford the best means of procuring 
 it, after the haemorrhage has stopped ; but it can be obtained 
 in larger quantity from animals *, after portions of muscle 
 have been cut away under the skin, and consequently from 
 wounds with a loss of substance. A perfectly fresh exudation 
 of this kind exhibits all the physical and chemical characters 
 of the intercellular fluid of the blood. In the fluids of this 
 kind examined by Lehmann f , he always found more water, 
 less albumen, and more phosphates and potash-salts than in 
 the corresponding liquor sanguinis. He could not determine 
 the relative proportions of fibrin : in birds (his experiments 
 were made on rabbits and geese) there was always rather 
 more fat in the exudation than in the blood -plasma. 
 
 Eecent exudations in the. rare cases in which we obtain 
 them from serous sacs in the human subject, present very 
 different characters, being always separated into a coagulum 
 and a fluid. 
 
 The coagulum varies very much in form and colour ; its 
 microscopical characters are principally those of spontaneously 
 coagulated fibrin, but in addition to swollen and almost 
 spherical blood-discs, it usually contains granules, nuclei, and 
 .occasionally cytoid corpuscles ; it swells in water containing 
 hydrochloric or acetic acid, but does not form a mass of such 
 perfect translucence as the fibrin of the blood. 
 
 The fluid portion is generally clear and transparent, only 
 becoming opalescent and turbid after the exudation has re- 
 
 * Birds, not being prone to suppuration, are the best animals to use. Frogs 
 cannot be employed in consequence of the large quantity of lymph, which is 
 poured out of their subcutaneous lymphatics, and vitiates the purity of the exu- 
 dation. 
 
 f Physiological Chemistry, vol. iii. pp. 133 and 150, 
 
 c c 2 
 
388 PHYSIOLOGICAL CHEMISTRY. 
 
 mained for some time in the cavity. The reaction is com- 
 monly less alkaline than that of blood-serum. Albumen is 
 precipitated from it on boiling, either in curd-like clots, or in 
 a gelatinous mass, and the filtered fluid forms the so-called 
 casein-membrane on its surface an indication, however, in this 
 case not of the presence of casein, but of an alkaline albumi- 
 nate (see p. 106), for both the rennet-test and acetic acid 
 here give negative results. The salts and extractive matters 
 resemble those occurring in the blood. The quantitative com- 
 position of these exudations when compared with that of the 
 corresponding blood, is by no means fixed. The relative 
 quantities of fibrin cannot be determined. No definite ratio 
 seems to exist between the part of the exudation which remains 
 fluid, and the serum of the corresponding blood, but generally 
 the solid residue of the fluid portion of the exudation is 
 inconsiderable, and consequently there is a relative excess of 
 water. There is usually less of the coagulable protein- sub- 
 stances, but rather more of extractive matter in the exuda- 
 tion-fluid than in the corresponding blood-serum. The col- 
 lective salts are somewhat higher in the exudations than in 
 the blood-serum, and on comparing the individual salts, we 
 find without exception relatively and absolutely more phos- 
 phates and potash-salts in all the exudations that have been 
 examined than in the blood-serum. 
 
 Passing without remark over the croupous, tuberculous, 
 and albuminous forms of exudation, on which chemistry has 
 as yet thrown no satisfactory light, we proceed to the consider- 
 ation of the purulent exudation. 
 
 Pus (298.) The purulent exudation, or pus, occurs as a thick 
 
 yellowish fluid, which differs from every other exudation by 
 
 containing a large number of corpuscles, which are distributed 
 
 through it with tolerable uniformity. Hence pus, like blood, 
 
 consists of corpuscles and an intercellular fluid or serum. 
 
 Pus-cor- These corpuscles, which commonly range from 0-004 to 0-005 
 
 puscles. Q f a ijjjg ^ di ame ter, consist of a cell-membrane, which often 
 
EXUDATIONS. PUS. 389 
 
 appears granular, of viscid transparent contents, and of a 
 nucleus that adheres to the cell-wall, and therefore lies ec- 
 centrically. As no chemical or microscopical differences can 
 be observed between these pus-corpuscles and the colourless 
 blood-corpuscles, the lymph-corpuscles, and rnucus-corpuscles, 
 Henle has proposed to call them all by the common name of 
 cytoid (or cell-like) corpuscles. See' Plate V. fig. 8 (a). 
 
 Difficult as it is to separate the red corpuscles from the 
 blood, it is still more difficult to separate these corpuscles 
 from the surrounding intercellular fluid. No addition of any 
 saline solution will here render the fluid capable of nitra- 
 tion. Like the blood-corpuscles, they possess a sinking 
 tendency, but they sink so slowly, that the pus begins to 
 become decomposed before the process is nearly accomplished. 
 
 Pus when exposed to the air, very soon begins to exhibit Fermenta- 
 certain changes. It may undergo either acid or alkaline 
 fermentation, the latter being equivalent to ordinary putre- 
 faction. Acid pus is probably of very jare occurrence in the 
 animal body (as far as I know, only having been met with in 
 a few cases of empyema, and of phthisical sputa), and this is 
 the more remarkable because pus rapidly loses its normal 
 alkaline reaction when exposed, in a corked bottle containing 
 air, to a summer temperature, and in the course of time 
 becomes acid. It forms both volatile and fixed fatty acids : 
 butyric acid can be chemically detected in it, and margaric 
 acid is liberated from the pre-existing neutral fat which nor- 
 mally exists in pus, and may be readily detected by the 
 microscope (see Plate V. fig. 8 &).* The acids which are thus 
 generated act in the same manner as dilute acids do when 
 added to fresh pus ; that is to say, they render the cell-wall 
 
 * After pus has stood for some months, the different fats appear in the most 
 beautiful forms, such as no artificial means are able to produce. Under the 
 microscope we see confused masses of fine threads of margarin, and ensiform, 
 or lily-leaf-shaped, variously contorted bundles of crystals of margaric acid, 
 together with tablets of cholcsterin. 
 
 c c 3 
 
390 PHYSIOLOGICAL CHEMISTRY. 
 
 transparent, and bring the previously concealed nuclei into 
 view. 
 
 Pus, when mixed with mucus or blood, or when secreted 
 on an unhealthy-looking surface, rapidly undergoes alkaline 
 fermentation, without having previously become acid. It 
 begins to evolve ammonia and hydrosulphate of ammonia ; 
 the cytoid corpuscles become destroyed or run together into 
 a gelatinous mass ; nuclei are no longer to be seen either 
 isolated or in the corpuscles ; and at length the only morphotic 
 elements are molecular granules and vibriones. 
 
 The cytoid corpuscles are readily acted on by endosmotic 
 currents ; their diameter depending to a great extent on the 
 specific gravity of the fluid in which they float ; hence in 
 saliva they are larger, and in blood they are smaller, than in 
 purulent serum. 
 
 Since the intercellular fluid of pus doubtless bears a de- 
 finite relation to the intercellular fluid of the blood, it ob- 
 viously follows that in those diseases in which the specific 
 gravity of the liquor sanguinis is altered, there will like- 
 wise be an alteration in the size of the pus-corpuscles. F^r 
 if we dilute pus with distilled water, we observe that the 
 corpuscles become much swollen, that the cell-membrane 
 loses its granular character, and that the nucleus consequently 
 is brought distinctly into view : some corpuscles even burst 
 from he absorption of water. 
 
 Very dilute mineral acids and moderately dilute organic 
 acids, act similarly to water, and may be employed (acetic 
 acid for instance) in bringing the nuclei into view. When 
 the nucleus is originally visible, and of a simple lenticular 
 form, it retains this appearance after the addition of acids, 
 but in those cases in which it is originally invisible, or where 
 its appearance can only be detected by a dark spot in the 
 corpuscle, the nucleus is generally tripartite. 
 
 Solutions of neutral alkali-salts contract and shrivel the 
 corpuscles by extracting their water : they lose their clearly 
 
EXUDATIONS. I>US. 391 
 
 defined outline and are converted into minute granular jagged 
 bodies ; while the caustic alkalies rapidly destroy the cor- 
 puscles. 
 
 Pus-corpuscles are entirely destroyed by the addition of 
 bile, or of solution of glycocholate, taurocholate or cholate 
 of soda.* 
 
 As incidental morphotic constituents of pus, we often meet 
 with fat-globules, blood- corpuscles, epithelium, granular or 
 exudation cells, fragments of connective tissue, &c. 
 
 The serum of pus is perfectly clear, colourless, or very The serum 
 faintly yellow, of a weak alkaline reaction, and coagulates on 
 the application of heat into a dense white mass. Its principal 
 constituent is albumen, which occurs in it in varying propor- 
 tions, from 1-2 to 3-7-g-. 
 
 Certain modifications of the protein-bodies, known as mucin 
 and pyin, are occasionally found in the pus-serum : casein, 
 or a substance closely allied to it, chondrin, glutin, and 
 leucine, have also been found.f 
 
 The chemical characters of mucin have been already de- 
 scribed (see p. 287). Pyin, which was discovered by Giiterbock Pyin. 
 in pus, but which is by no means an invariable constituent 
 of that fluid, may be described as a derivative from the 
 protein-bodies, which is precipitated from its watery solution 
 by acetic acid, but is perfectly insoluble in an excess of that 
 acid, while hydrochloric and nitric acids only cause a slight 
 turbidity, which disappears on the addition of an excess of 
 the reagent. It is precipitated by alum, but not by ferrocyan- 
 ide of potassium, from its hydrochloric-acid solution ; neutral 
 acetate of lead and corrosive sublimate likewise throw it down. 
 It is not coagulated by heat. Mulder regards pyin as 
 identical with a substance which he had previously obtained 
 by the prolonged boiling of certain albuminates in water, 
 
 * Von Dusch, Beitrage zur Pathol. des Icterus, u. s. w. 1854, pp. 1115. 
 f Bodeker in Zeits. f. rat. Med., New ser. vol. vii. p. 146, &c. 
 
 c c 4 
 
392 PHYSIOLOGIC A.L CHEMISTRY. 
 
 and which he afterwards discovered in the blood and in fluid 
 exudations, and to which, from its composition, he had given 
 the name of tritoxide of protein. Lehmann expresses the 
 opinion that the substance referred to by Mulder as occurring 
 in the blood and exudations more closely resembles the 
 peptones (which are briefly alluded to in the remarks " On 
 the Grastric Juice " in p. 161, and are more fully noticed in 
 the chapter " On Digestion ") than pyin, since it is not thrown 
 down by acetic acid. 
 
 Fat. The fat probably belongs more to the corpuscles than to 
 
 the serum. The fatty matter extracted by ether consists not 
 only of olein and margarin, but of oleic and margaric acids, 
 and of cholesterin. The collective fats vary from 2 to 6^- of 
 the fluid pus, the cholesterin alone often reaching 1-g-. 
 
 Solid con- The solid constituents of normal pus ran ere from 14 to 16. 
 stituents. 
 
 The solid residue contains 5 or 6^- of mineral constituents, 
 
 the soluble salts being to the insoluble in about the ratio of 
 Salts. 8 to 1. Of the soluble salts, the chief is chloride of sodium, 
 
 which is three times as abundant as in the serum of the 
 blood : the soluble phosphates in the ash range from 3 to 10^. 
 The insoluble salts consist of the phosphates of lime and 
 magnesia, with a little sulphate of lime and peroxide of iron. 
 In the pus as in all other exudations, we meet with bile- 
 pigment, the resinous acids of the bile *, urea, and sugar, as 
 incidental constituents. 
 
 * Lehmann states that one of his pupils found glycocholate and taurocholate 
 of soda in pus from an abscess in the thigh of a patient with jaundice. The 
 action of the bile, described by Von Dusch, seems not to have been noticed in 
 this case. 
 
393 
 
 CHAPTER XVI. 
 
 THE SOLID TISSUES OF THE BODY. 
 
 SECTION I. THE OSSEOUS TISSUE. 
 
 (299.) THE bones are the most indestructible of all the The os- 
 parts of the animal organism ; human and animal bones at J 6 gU? m 
 least 3000 years old, discovered in Egyptian tombs, being 
 found to present the same composition as perfectly recent 
 bones ; and even fossil bones of extinct animals scarcely differ 
 in any important point from the normal type. 
 
 Bone consists chemically of animal and earthy or inorganic Composed 
 
 The external surface of bone is covered by periosteum (a s amc 
 membrane provided with nerves and vessels), which, as well 
 as the cartilaginous portion, can be converted by boiling into 
 gelatin. If a bone is suspended in dilute hydrochloric acid 
 at a low temperature, all the earthy matter becomes gradually 
 dissolved, and the mere cartilage remains, retaining the 
 precise form of the original bone. It is supple, transparent, 
 and soft ; but, on drying, it becomes of a darker colour, hard, 
 and somewhat shrivelled, and when boiled becomes rapidly 
 converted into gelatin, leaving the vessels, &c., unacted on. 
 When bone is submitted to thorough incineration, all the 
 organic portion is destroyed, and nothing remains but the 
 earthy matter mixed with certain salts, which have been 
 formed during the process of incineration (such as carbonates 
 of the alkalies), and with free lime, formed by the expulsion 
 of the carbonic acid from carbonate of lime. These two 
 simple experiments suffic'e to show that both organic or animal, 
 
394 PHYSIOLOGICAL CHEMISTRY. 
 
 and inorganic or earthy constituents enter largely into the 
 composition of bone. 
 
 In addition to cartilage, which forms the great mass of the 
 animal matter, the bones of all the vertebrata are found to 
 contain fat (which occurs in very varying quantities) and 
 albuminoid matter, which is not convertible into gelatin, 
 and which seems to be derived partly from the blood-vessels, 
 and partly from the membranous structure which has been 
 proved by histologists to line the minute cavities commonly 
 known as bone-corpuscles. The inorganic constituents of 
 bones, which usually form considerably more than half the 
 mass, are mixed in various proportions, and consist of phos- 
 phate of lime (3CaO.P0 5 ), which is always the prepon- 
 derating ingredient, of carbonate of lime, and of a little 
 fluoride of calcium and phosphate of magnesia. The dis- 
 covery by Von Bibra that the bone-ash of reptiles and fishes 
 (see p. 137) contain soluble sulphates, is deserving of special 
 notice, because, as a general rule, the bone-ashes of most 
 animals do not contain a larger amount of soluble salts 
 (chloride of sodium and carbonate of soda) than might be 
 referred to the juices permeating the bones. 
 
 The bone-cartilage or ossein (as certain recent writers 
 term it) is obtained in the manner we have already described 
 by means of dilute hydrochloric (or nitric) acid. If the 
 action of the acid has been continued for a sufficiently long 
 time, the ossein yields on incineration a mere trace of ash, 
 and its atomic composition has been found to be precisely 
 identical with that of the glutin which is derived from it by 
 boiling. Fremy * has shown that the ossein of mammals, 
 birds, amphibians, reptiles, and fishes is identical, and that the 
 age of the individual has no effect on its composition. It is 
 found, however, that in the embryo, even up to the latest 
 period of intra-uterine life, the bones yield no glutin, and, 
 
 * Ann. de Chim. ch. dc Phys., 3 ser. vol. xliii. pp. 47107. 
 
THE OSSEOUS TISSUES. 
 
 395 
 
 therefore, must contain a substance differing essentially from 
 ossein. It appears from the investigations of Von Bibra* and 
 Ragsky f that the character of the ossein is not affected by 
 disease of the bone. 
 
 In the bones of certain water-birds and fishes Fremy found 
 a substance which, although isomeric with ossein, differed 
 from it in not yielding gelatin on boiling ; and which, when 
 treated with hydrochloric acid, yielded a white, transparent, 
 elastic substance. 
 
 The fat which occurs in the analysis of well-macerated 
 bones is for the most part due to the presence of marrow, 
 &c. ; very little fat (olein) exists in the true osseous tissue. 
 
 The organic matters occurring in bone range from 30 to 
 4Og, about 33-J being the average in the human subject. 
 
 The following analyses by Von Bibra of different bones from Analyses 
 the body of a man aged twenty-five or thirty years, will serve {Jonef o'f Q * 
 at the same time to give a general idea of the chemistry of the body, 
 bone, and to show how the composition of the different bones 
 varies in the same subject : 
 
 
 
 Femur. 
 
 Tibia.- 
 
 Humerus. 
 
 Ulna. 
 
 Os occipitis. 
 
 Costa. 
 
 Phosphate of lime with a 1 
 little fluoride of calcium J 
 
 59-63 
 
 58-95 
 
 59-87 
 
 59-30 
 
 58-43 
 
 55-66 
 
 Carbonate of lime . 
 
 . 
 
 7-33 
 
 7-08 
 
 7-76 
 
 7-35* 
 
 8-00 
 
 6-64 
 
 Phosphate of magnesia 
 
 . 
 
 1-32 
 
 1-30 
 
 1-09 
 
 1-35 
 
 1-40 
 
 1-07 
 
 Soluble salts . 
 
 . 
 
 0-69 
 
 0-70 
 
 0-72 
 
 6-73 
 
 0-90 
 
 0-62 
 
 Cartilage . 
 
 ; 
 
 29-70 
 
 30-42 
 
 29-28 
 
 29 : 98 
 
 29-92 
 
 33-97 
 
 Fat . 
 
 . 
 
 1-33 
 
 1-55 
 
 1-28 
 
 1-29 
 
 1-35 
 
 2'04 
 
 In his different analyses of human bone Von Bibra found 
 the phosphate of lime with fluoride of calcium to range from 
 63-17 to 42-32, the carbonate of lime from 10-9 to 4-46, .and 
 the phosphate of magnesia from 1-72 to 11*89. 
 
 Lehmann gives the following numbers as representing the 
 average composition of the mineral constituents in 100 parts 
 of bone : 57 parts of phosphate of lime, 8 of carbonate 
 
 * Chem. Untersuch. iiber die Knochen u. Zahne, 1844. 
 f Quoted in Rokitansky's Morbid Anatomy. 
 
396 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Bones at 
 different 
 ages. 
 
 Bones of 
 mammals 
 generally, 
 
 of birds, 
 
 of lime, 1 of fluoride of calcium, and from 1 to 2 of phosphate 
 of magnesia. 
 
 From the analyses of different bones of the same person, 
 it appears that the bones of the extremities are richer in 
 mineral constituents than those of the body (the vertebrae, 
 os innominatum, ribs, &c.), and that the femur and humerus 
 are more earthy than the other long bones ; that the cranial 
 bones closely resemble the latter in this respect, while the 
 metacarpal and metatarsal bones resemble those of the trunk. 
 The spongy bones contain rather more organic matter than 
 the others ; the short bones contain the most fat, and the flat 
 bones the most water. 
 
 Neither age nor sex seems to impress any special character 
 on the composition of bone. In the following table all the 
 analyses are by Von Bibra, and the selected bone is the femur. 
 We give only the most important constituents viz., phos- 
 phate of lime, including fluoride of calcium, carbonate of lime, 
 and cartilage. 
 
 
 Child 
 
 Child 
 
 Woman 
 
 Man 
 
 Woman 
 
 
 9 months. 
 
 5 years. 
 
 25 years. 
 
 58 years. 
 
 78 years. 
 
 Phosphate of lime 
 
 48-1 
 
 - 60-0 
 
 57-4 
 
 58-2 
 
 57-4 
 
 Carbonate of lime 
 
 6'1 
 
 5'9 
 
 8-9 
 
 8'4 
 
 7-5 
 
 Cartilage 
 
 417 
 
 31'3 
 
 29-5 
 
 31-4 
 
 32-1 
 
 The researches of Von Bibra and Fremy on the bones of 
 mammals show that a larger amount of carbonate of lime 
 occurs in the bones of herbivorous than in those of carnivorous 
 animals, and that the bones of pachyderms and cetaceans are 
 especially rich in this constituent. (In the spongy substance 
 of the femur of ahorse Von Bibra found 1 8 -9 of carbonate of 
 lime.) They likewise show that the bones of birds contain 
 relatively more earthy matters than those of mammals (some- 
 times, as in the Rasores, amounting to 76 or even 84) ; that 
 in birds the ratio in which the carbonate of lime stands to the 
 phosphate, is higher than in mammals; that the bones of 
 granivorous birds always contain a little silica, and that birds' 
 bones contain more fat than those of mammals. 
 
THE TEETH. 397 
 
 The bones of amphibians, reptiles, and fishes, are compa- of reptiles 
 ratively poor in mineral constituents, and their ash always 
 contains sulphate of soda. Fishes' bones are richer in fat and 
 in water than any other bones. 
 
 In almost all diseased bones we find a diminution of the Morbid 
 mineral constituents, and often an excess of fat. Analysis 
 has not done much to elucidate the nature of the various 
 morbid processes occurring in bone, and it will suffice if I 
 direct the reader's attention to the fact that he will find the 
 most trustworthy results on this subject collected in the second 
 volume of Simon's "Animal Chemistry," pp. 406 413. 
 
 SECTION II. THE TEETH. 
 
 (300.) The teeth are composed of dentine, enamel, and The teeth, 
 cement. 
 
 The chemical composition of dentine is very similar to that Dentine, 
 of bone ; the quantitative ratio between the organic and in- 
 organic constituents approximating very closely to that occur- 
 ing in the denser bones, and averaging 28 : 72. From 3 to 8 
 of carbonate of lime has been found with from 65 to 67- of 
 phosphate of lime, together with a little fluoride of calcium 
 and phosphate of magnesia. 
 
 The enamel yields no cartilage, and often contains not Enamel, 
 more than 2-g- of organic matter (apparently membranous 
 tissue). In the enamel of human teeth, Berzelius found 
 
 Phosphate of lime with fluoride of calcium . 88-5 
 
 Carbonate of lime . . . .8-0 
 
 Phosphate of magnesia . . 1 "5 
 
 Membrane, alkali, and water . . 2-0 
 
 x . "- 
 
 Nearly similar results have been obtained by Von Bibra 
 and Fremy. The former chemist found as much as 4-g- of 
 fluoride of calcium in the enameL 
 
398 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Cement. 
 
 Carious 
 teeth. 
 
 The cement has been very imperfectly examined, but it 
 seems to be chemically almost identical with bone. 
 
 The researches of Lassaigne and Von Bibra on the teeth of 
 different animals, have yielded no very important results. 
 No definite difference could be detected between the teeth of 
 herbivorous and carnivorous animals. 
 
 According to Marchard, carious teeth contain an excess of 
 carbonate of lime. 
 
 SECTION III. CARTILAGE. 
 
 True car- 
 tilage. 
 
 Fibre-car- 
 tilage. 
 
 (301.) We must distinguish between true cartilage and 
 fibre-cartilage. 
 
 True cartilage consists of a uniform-looking matrix which 
 presents numerous small cavities containing nucleated cells. 
 On closer (microscopic) examination, the matrix is however 
 seen to be either granular or fibrous. In either case, on boiling 
 the cartilage in water for a prolonged period (from 12 to 48 
 hours, according to its solubility), or on exposing it to the 
 action of a Papin's digester for one hour, everything dissolves 
 excepting the cells. Hence it is only the matrix or inter- 
 cellular substance which yields chondrin ; the chemical com- 
 position of the cartilage-cells being obviously different from 
 that of the structure in which they are embedded. 
 
 Fibro-cartilage presents a more decidedly fibrous matrix 
 than true cartilage, the cells having apparently the same 
 structure in both varieties. The gelatin yielded by this 
 fibrous intercellular substance is, however, not identical with 
 the chondrin obtained from true cartilage, for its solution 
 is only slightly precipitated by tannin, and the alum-pre- 
 cipitate, although abundant and compact, does not redissolve 
 in an excess of the test. 
 
 No very accurate quantitative analyses of cartilage have 
 been made. Dried cartilage yields from 2 to 5-g- of fat, which 
 
THE TEETH. 
 
 399 
 
 seems to be chiefly deposited in the cells. In fresh cartilage 
 the water ranges from 54 to 70-g-. The costal cartilages con- 
 tain from 3 to 6-g- of mineral constituents, consisting of the 
 phosphates of lime and magnesia, chloride of sodium, car- 
 bonate of soda, and sulphates yielded by the organic matters 
 in the process of incineration. 
 
 SECTION IV. THE HORNY TISSUES. 
 
 (302.) Under the term horny tissue, we include epidermis, Horny 
 nails, claws, hoofs, horns, whalebone, tortoiseshell, hair, 
 wool, &c. 
 
 These substances are much more interesting in their histo- 
 chemical, than in their general chemical relations ; and we 
 shall only notice a few isolated points on which chemistry 
 has thrown some light. 
 
 The following table shows the elementary composition of Their ulti- 
 several of the substances belonging to this group, after being p OS i t i on . " 
 boiled in water, alcohol, and ether. 
 
 Epidermis XT M 
 from sole of foot. /JJH* * 
 (Mulder.) (Mu der -> 
 
 Horses' 
 Hoof. 
 (Mulder.) 
 
 Cows' 
 Horn. 
 (Tilanus.) 
 
 Hair. 
 (Laer.) 
 
 Wool. 
 (Scherer.) 
 
 Carbon 
 
 50-28 
 
 51-00 
 
 51-41 
 
 51-03 
 
 50-65 
 
 50-65 
 
 Hydrogen . 
 
 676 
 
 6-94 
 
 6-96 
 
 6-80 
 
 6'36 
 
 V 7'03 
 
 Nitrogen 
 
 17-21 
 
 17-51 
 
 17-46 
 
 16-24 
 
 17-14 
 
 17-71 
 
 Oxygen 
 
 25-01 
 
 21-75 
 
 19-49 
 
 22-51 
 
 20-85 T 
 
 24-61 
 
 Sulphur 
 
 0-74 
 
 2-80 
 
 4-23 
 
 3-42 
 
 5-00 J 
 
 
 By prolonged boiling (for several days) in sulphuric acid, 
 most of these substances yield tyrosine and leucine (see pp. 
 32, 34). 
 
 Von Bibra has determined the percentage of sulphur in a 
 number of the substances of this class. In cows' horn he 
 found 3-04, in the hoof of the deer 3*02, in the claw of the 
 dog 2*7, in human nails 2'73, in whalebone 3*49, and. in 
 human hair, as the mean of 46 determinations, 4-83 (the 
 extremes being 3-92 and 8-23). 
 
 Laer, who has carefully studied the chemistry of the hair, The hair. 
 
400 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Glycogen 
 in the 
 horny 
 tissues in 
 foetal life. 
 
 Composi- 
 tion and 
 
 was unable to obtain any special pigment from it, but the 
 microscope revealed the presence of pigment-granules in the 
 cortical substance. He ascribes the whiteness of the hair of 
 aged persons to the presence of air in it. The view main- 
 tained by Vauquelin, that the colour of the hair is influenced 
 by the amount of iron which it contains, seems to be without 
 foundation. 
 
 The quantity of fat extracted by Von Bibra from the hair of 
 men and animals varied from 0*023 to 4-43. In this fat 
 Laer found only margarin, olein, and margaric acid, but Von 
 Bibra also discovered cerebric acid. In cows' horn he found 
 2'1, and in the cast-off skin of a snake 7 g- of fat. 
 
 The inorganic matters in this class of tissues scarcely aver- 
 age !--. Epidermis yields from 1 to 1*5, the nails 1, whale- 
 bone !!, tortoiseshell 0-5, hair from 0'3 to 2 in man (although 
 more than 4 in certain animals), wool from 0'8 to 2, and 
 feathers from 0-7 to 1'8-. 
 
 According to Von Bibra the ash yielded by hoofs contains 
 much sulphate of lime and sulphate of magnesia, smaller 
 quantities of silica and earthy phosphates, traces of chlorine 
 and iron, and no carbonic acid. The hair both of men and ani- 
 mals contains the same substances, with traces of carbonates 
 and fluorides. The silica in human hair amounts to about 
 0*2 ; in feathers it is much more abundant, sometimes form- 
 ing one half of the ash. 
 
 Bernard has recently discovered that (in many animals), 
 during the first half of intra-uterine life, glycogen occurs in 
 those cells which form, or precede the formation of, the horny 
 tissues, as, for instance, the epithelium and epidermis, the 
 hoofs, claws, and incipient horns. 
 
 As most of our knowledge of this substance, glycogen, has 
 been obtained since the portion of this volume, treating of 
 the sugars, was printed (1857), I shall here introduce a 
 brief notice of it. 
 
 Glycogen was discovered in the liver by Bernard, and has 
 
MUSCULAR TISSUE. 401 
 
 been analysed by Pelouze, who assigns to it the formula proper-tie? 
 CjgHjjOjpHO. Its properties seem to indicate that it should 
 be placed between starch and dextrine. In contact with 
 saliva, pancreatic juice, or diastase, it becomes rapidly con- 
 verted into sugar ; and the presence of blood or of the paren- 
 chyma of the liver induces the same change in it. It occurs 
 as an amorphous matter in the hepatic cells. During foetal 
 life, before the liver begins to discharge its proper functions, 
 it is, however, not found in that organ ; but it has then been 
 found by Bernard, in special cells in the placenta (in the 
 rodents) or in aggregations of cells distributed over the 
 amnion, also in the foetal muscles, lungs, &c. In severe 
 forms of disease, and especially in febrile affections, it seems 
 to be temporarily absent from the liver. 
 
 SECTION V. MUSCULAR TISSUE. 
 
 (303.) Muscular tissue, whether smooth or striated, being Muscular 
 made up of different morphotic elements which it is im- t! 
 possible to separate, is not well adapted for ordinary chemical 
 investigation, although micro-chemical or histo-chemical re- 
 searches have thrown much light on its nature and composi- 
 tion. 
 
 We begin with the consideration of smooth muscle, which Smooth 
 consists mainly of nucleated contractile fibre-cells, grouped 
 together in bundles and layers, and permeated by a muscular 
 juice ; no sarcolemma being detectible. 
 
 The substance of which the cells are composed is soluble in 
 very dilute hydrochloric acid (1 to 1000), and on neutralising 
 the acid solution we have at first a hardly perceptible jelly, 
 which after a time collects in flakes at the bottom of the 
 vessel. These flakes are soluble in lime-water, and on the 
 application of heat the solution coagulates as if it contained 
 albumen ; they likewise dissolve readily in alkalies and very 
 dilute acids, but not in solution of carbonate of potash or in 
 
 D D 
 
402 PHYSIOLOGICAL CHEMISTRY. 
 
 water. Hence (see p. 112) this substance is perfectly identical 
 with the syntonin or fibrin of striped muscle. 
 
 The juice or fluid permeating the smooth muscular tissue 
 approximates much more closely in its chemical characters to 
 the corresponding fluid which moistens the striped tissue, than 
 to the blood-plasma or any other fluid. It is, however, usually 
 neutral or even faintly alkaline * in its reaction, whereas the 
 ordinary juice of striped muscle is acid; in addition to 
 albumen it contains more or less casein f , creatine, hypoxan- 
 thine, very small quantities of lactic, butyric, acetic, and 
 formic acids, and a relative but not an actual excess of the 
 potash over the soda compounds.^ 
 
 The muscular tissue of the Mollusca is of the smooth or 
 unstriped variety. Valenciennes and Fremy have recently 
 examined the flesh of acephalous molluscs, and cephalopods, 
 and have found that in addition to creatine and creatinine, it 
 contains considerable quantities of taurine (see p. 53), and of 
 super-phosphate of lime, which latter substance imparts to 
 the tissue an acid reaction ; they likewise detected oleophos- 
 phoric acid in small quantity. 
 
 Striped On examining the primary bundles of striated muscular 
 
 fibre after the removal (as far as possible) of all extraneous tis- 
 sues, we find that it presents three morphotic elements, which, 
 as micro-chemical investigations show us, are altogether dis- 
 tinct from one another in composition, namely, the fibrils, the 
 nuclei, and the sarcolemma. 
 
 The substance forming the fibrils contained within the 
 
 * This statement is not universally true. Lehmann found that the juice from 
 the muscular coat of the stomach of the pig was distinctly acid, although less 
 so than that derived from striped muscle ; and the corresponding fluid from 
 the middle arterial coat of the ox was found by the same chemist to be acid, 
 although Schultze had described it as alkaline. 
 
 f Schultze found no less than 7 - 24g of casein in the well dried muscular coat 
 of the aorta. Ann. d. Chem. u. Pharm. vol. Ixxi. pp. 277 293. 
 
 J The ratio of the potash to the soda was as 38 : 62 in the juice from the 
 muscular coat of the pig's stomach, and as 42 : 58 in that of the middle coat of 
 the arteries. 
 
MUSCULAR TISSUE. 403 
 
 sheaths of sarcolemma is the most important constituent. It Substance 
 seems to be identical with the syntonin described in p. 112, 
 for on treating well-prepared muscular fibre, either on a 
 comparatively large scale, or under the microscope, with a 
 dilute solution of hydrochloric acid (1 part to 1000), we 
 observe that the sarcolemma-tubes gradually discharge their 
 contents, after which syntonin is found in the solution. We 
 must, however, recollect that, as we obtain this substance for 
 the purpose of analysis, it is in a coagulated state, while 
 during life, or as long as muscle retains its characteristic 
 irritability, it exists within the sarcolemma in a soluble form ; 
 and we have no means of ascertaining what changes albumi- 
 nous bodies of this kind undergo in the process of coagulation. 
 In the coagulation of globulin and of hsematocrystallin an 
 acid seems to be separated (see p. 217) when either of these 
 substances is coagulated by boiling ; and Kiihne, in watching 
 the soluble syntonin escaping from t the sarcolemma-tubes of 
 frogs' muscles, thought that he saw indications of the presence 
 of a free acid during its spontaneous coagulation. .Hence 
 the fibril-substance, on which histo-chemical observations are 
 made in the syntonin which we submit to analysis, is pro- 
 bably a mere derivative or product of decomposition of the 
 preponderating substance in living muscle. 
 
 Various histo-chemical reactions presented by the sarco- 
 lemma, and its incapacity of being converted by boiling into 
 gelatin, indicate that it is not allied to connective tissue; 
 its elasticity, which is unaffected by the action of either acids 
 or alkalies, seems to connect it with elastic tissue. The 
 granules which are brought to view in the sarcolemma when 
 it is emptied of its contents by the action of acids or alkalies 
 consist chiefly of fat. 
 
 The chemical nature of the nuclei, which are embedded in Substance 
 the sarcolemma, has not been clearly made out ; but they 
 seem in many respects to resemble, although they are not 
 identical with, the substance of the fibrils.- 
 
 D D 2 
 
404 PHYSIOLOGICAL CHEMISTRY. 
 
 The mus- The fluid which permeates and surrounds the various mor- 
 ' u ar Juice ' photic elements, the muscular juice, next claims our attention. 
 This juice, when we express it from the muscular tissues of 
 men or animals after their death, is almost always acid. The 
 Its reac- cause of this acidity was maintained long ago by Berzelius 
 to be lactic acid, while Liebig subsequently showed in his 
 admirable " Researches on the Chemistry of Food," that the 
 acidity is due to the simultaneous presence of lactic acid and 
 acid phosphate of lime. Subsequent observers (Von Bibra 
 and Enderlin) have found the intensity of the reaction varia- 
 ble, and have even observed that in perfectly fresh flesh the 
 reaction is sometimes neutral. Du Bois Eeymond has just 
 (1859) shown, by a series of most carefully conducted experi- 
 ments, that fresh or living muscles (muscles still sensitive to 
 galvanic stimulus) do not exhibit an acid reaction, but rather 
 tend to alkalinity. He has further shown that the acid re- 
 action only ensues with the commencement of the rigor 
 mortis or the coagulation of the syntonin. This view is in 
 strict accordance with the facts previously observed by Kiihne, 
 to which we have already adverted. Hence it would appear 
 that there is an intimate connection between the acid reaction 
 and the coagulation of the syntonin. There are, however, as 
 Du Bois Eeymond subsequently discovered, certain conditions 
 under which perfect coagulation of the syntonin may occur > 
 without the development of free acid in the muscles. For by 
 a comparatively high degree of heat, by concentrated solu- 
 tions of chloride of sodium, or sulphate, or nitrate of potash, 
 or by the action of alcohol, the syntonin may be coagulated in 
 the living (that is to say, the fresh and still irritable) muscle, 
 without the development of an acid reaction; the muscle 
 under these conditions presenting a neutral or faintly alkaline 
 reaction. The occurrence of the acid reaction is further 
 shown to be perfectly independent of the access of atmo- 
 spheric air. 
 
 Although the rigor mortis is the ordinary condition that 
 
MUSCULAR TISSUE. 405 
 
 leads to the development of free acid by the syntonin, there 
 are other ways and modes by which it may liberate a free 
 acid ; for Du Bois Reymond has convinced himself, by a 
 series of experiments on frogs, rabbits/ and dogs, of the fact 
 noticed many years ago by Berzelius, that the acidity is in- 
 creased in muscles that had been previously strongly exer- 
 cised; and that during life the muscles may temporarily 
 attain an acid reaction, as a consequence of often-repeated 
 contractions, which disappears after sufficient rest, when they 
 return to their normal neutral, or faintly alkaline reaction. 
 Muscles, which like the heart are in a state of perpetual 
 activity, are not always found to exhibit an acid reaction, 
 but the free acid is developed in them earlier than in other 
 muscles. 
 
 We must regard it then as an established fact that the 
 muscles, in the exercise of their normal functions, develop a 
 free acid, but we are not in a position to affirm with certainty 
 that this acid is identical with the lactic acid which is yielded 
 by dead muscular tissue. Valenciennes and Fremy refer the 
 acid reaction of muscular juice to acid phosphate of potash, 
 but this view is opposed by the fact (quoted by Du Bois 
 Reymond) that this salt has only a transitory action on litmus 
 paper, while the muscular juice permanently reddens it.* There 
 is no doubt that muscles which have become rigid after death, 
 contain a considerable quantity of free lactic acid ; but since 
 all this lactic acid is not formed (or, at all events, does not 
 appear) instantaneously, the phosphate of potash may be 
 converted, by its gradual agency, into an acid salt. 
 
 It was first proved by Gr. von Liebig that muscle is depen- Muscular 
 
 , T .i TT f -i ji i contraction 
 
 dent on oxygen to enable it to contract. He found that dependent 
 
 frogs' muscles retained their contractility much longer in an ^*g e ^ re " 
 atmosphere of oxygen than in one which did not contain that oxygen. 
 
 * In the case of perfectly fresh bullock's heart, it has however been observed 
 that, whatever may be the cause of the acid reaction, the reddening of the 
 litmus paper soon disappears. 
 
 T> D 3 
 
406 PHYSIOLOGICAL CHEMISTRY. 
 
 substance ; and he further showed that while a muscle is in a 
 state of contraction oxygen is absorbed, and a corresponding 
 quantity of carbonic acid is exhaled, facts which confirm the 
 view that a large portion of the carbonic acid formed in the 
 animal body is generated, not in the capillaries, but in the 
 parenchyma of the organs, and is especially produced by 
 muscular action. Subsequent experiments, made indepen- 
 dently by Matteucci and Valentin, show that the quantities of 
 absorbed oxygen and exhaled carbonic acid are proportional 
 to the contractions. 
 
 It has long been known that heat is liberated in muscles 
 by the act of contraction ; recent observations of Helmholz 
 and others show that this phenomenon may be observed even 
 in muscles from which the flow of blood has been cut off. 
 
 It has been further observed that the muscles of animals 
 that have been hunted to death, the muscles of men or 
 animals in whom death has been preceded by severe convul- 
 sions, as well as muscles whose energy has been exhausted by 
 repeated galvanic stimulation, become putrid much sooner 
 than muscles which were in a state of repose previously to 
 death. Muscles which during life have been thrown into 
 tetanic spasm, either by disease or by strychnine, become rigid 
 almost immediately after death, or in other words the syn- 
 tonin at once coagulates in them. 
 
 The muscular juice, as we obtain it for the purpose of exa- 
 mination, even if derived as rapidly as possible from the flesh 
 of recently killed animals, must obviously differ considerably 
 Physical from the fluid permeating the tissues during life. It occurs 
 mical cha- as a whitish or opalescent fluid of a more or less acid reaction, 
 thfmus^ and contains albumen, creatine, creatinine, hypoxanthine, 
 cular juice, inosite *, lactic acid, inosic acid, and several volatile acids, as 
 
 * I hardly know whether inosite should be regarded as an ordinary consti- 
 tuent of the muscular juice. Scherer (see p. 92) originally obtained it from 
 the heart of the ox, and it has been unsuccessfully sought for by Socoloff and 
 Panum (in Scherer's Laboratory) in the juice of other muscles. Lehmann, 
 however, states without giving his authority, that it is present in smaller quan- 
 
MUSCULAR TISSUE. 407 
 
 formic,, acetic, and frutyric acids ; it is probable, however, that 
 these volatile acids are the result of incipient decomposition. 
 Traces of uric acid have also been found in the muscular 
 tissue, but the most careful investigations have failed in 
 detecting the slightest indication of urea in the juice of 
 healthy muscular tissue, although it is found there in cases of 
 uraemia.* We do not know whether the muscles possess any 
 special pigment. Fat is always present, even after the most 
 careful removal of all visible traces of it. In addition to the 
 neutral fats, Valenciennes and Fremy maintain that this tissue 
 contains oleo-phosphoric acid. Bottcher found from 1-5 to 
 1'9{J- of fat in the muscular tissue of the human heart (or from 
 8 to 10 in the dried tissue), and Von Bibra found from 10 to 
 15-g- of fat in the dried muscle of the human thigh. 
 
 Muscles on being boiled yield from 2 to 6 g- of gelatin, which 
 arises from the connective tissue which holds together the 
 primitive bundles. 
 
 The soluble matters which can be extracted from muscular 
 tissue range from 6 to 8-g-. 
 
 With regard to the mineral constituents the potash-salts and 
 phosphates preponderate over the soda-salts and chlorides, 
 and the phosphate of magnesia amounts to about double the 
 phosphate of lime. 
 
 The amount of syntonin in the muscles is very variable ; it 
 appears to be more abundant in the muscles of old than of 
 .young animals. 
 
 titles in the other muscles. The unripe fruit of Phaseolus vulgaris, a kind of 
 bean, has been found by Voit to contain inosite a fact of interest, as an addi- 
 tional illustration of the frequent identity of animal and vegetable products. 
 Scyllite, a substance which in most of its properties closely resembles inosite, 
 has recently been discovered by Frerich's and Stadeler in the muscles and other 
 tissues of the Plageostomata, an order of cartilaginous fishes including the sharks, 
 rays, &c. Journ. f. pr. Chem. vol. Ixxiii. pp. 48 55. 
 
 * Small quantities of urea have been found in these cases by Buhl and Voit 
 (Zeits. f. rat. Med. New Ser. vol. vi. p. 94), and by Von Bibra (Ann. d. Chem. 
 u. Pharm. vol. xciv. pp. 206215). Strangely enough Frerichs and Stadeler 
 report that the muscles of the Plageostomata contain a considerable quantity of 
 urea, while the flesh of other fishes docs not yield a trace. 
 
 D D 4 
 
408 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Composi- 
 tion of 
 muscular 
 tissue. 
 
 Glycogen 
 in foetal 
 muscle. 
 
 The quantity of water in the muscles has been determined 
 by several chemists. Fresh muscular tissue from the ox 
 yielded 77'6 of water (Schlossberger), while human muscles 
 yielded from 72 '6 to 74'5-g- (Von Bibra), and the human heart 
 from 81 to 82-g- (Bottcher). The quantity of water in the 
 muscles of persons who have died from cholera is considerably 
 diminished and has been found as low as 69*1^. 
 
 The following table, drawn up by Lehmann, represents the 
 average composition of the muscular tissue of the ox: 
 
 Water 74-0 
 
 Solid constituents . . .26-0 
 
 Muscular fibre (syntonin) . 15*4 
 
 Gelatigenous substance . '* . . 0-6 
 
 Albumen . . . . 2-2 
 Creatine 
 Creatinine 
 
 80-0 
 
 20-0 
 
 17-7 
 
 1-9 
 
 3-0 
 
 Hypoxanthine 
 
 - Too small to be determined. 
 
 Inosite 
 Inosic acid 
 
 Fat 1-50 
 
 Lactic acid (C 6 H 5 5 .HO) . 0-60 
 
 Phosphoric acid . . . 0-66 
 
 Potash 0-50 
 
 Soda . . . . ~ . 0-07 
 
 Chloride of sodium . . , 0-04 
 
 Zinc ..... 0-02 
 
 Magnesia .... 0-04 
 
 2-30 
 0-68 
 0-70 
 0-54 
 0-09 
 0-09 
 0-03 
 0-05 
 
 Bernard has recently found glycogen in the muscles of the 
 various animals in the embryonic state. (Its result, sugar, he 
 had discovered in these organs some years previously. See 
 p. 90.) It is scattered over the sarcolemma-tubes in the form 
 of granules ; and may be found during the whole of intra- 
 uterine life, disappearing a few hours (6 to 24) after birth. 
 
THE BRAIN AND NERVOUS TISSUE. 409 
 
 SECTION VI. THE BRAIN AND NERVOUS TISSUE. 
 
 (304.) The various morphological elements entering into Nervous 
 the composition of nervous tissue, present many points of t] 
 difference in their chemical composition. 
 
 The investing membrane of the nerve-fibres shows by its Its mor- 
 micro-chemical reactions, that it does not .consist of areolar elements, 
 or connective tissue ; it seems to be allied to, though not 
 identical with, the protein-bodies. 
 
 The axis-cylinder consists of a protein-substance closely 
 allied to syntonin. 
 
 The medullary matter most probably consists of a soluble 
 protein-body and a dissolved fat. The addition of water 
 brings this substance into view, and is said to coagulate it, 
 but the appearance which is thus produced is more likely to 
 be caused by a separation of fat, than by the coagulation of a 
 protein-body. 
 
 Our knowledge of the constituents of the nerve-cells is very 
 imperfect. The cell-walls are slightly soluble in acetic acid, 
 and insoluble in carbonate of potash, and so far resemble 
 syntonin ; and the contents of the cells appear to consist partly 
 of a dissolved, and partly of an only swollen protein-substance, 
 together with a little fat. 
 
 The analysis of the collective nervous tissue (for it is im- 
 possible to separate the different morphotic constituents), 
 shows that it contains the following ingredients. 
 
 Besides albumen coagulable by heat, Von Bibra found in Composi- 
 the water-extract of the brain, various modifications of albu- 
 minous substances, which were not precipitated from their 
 solutions by boiling ; and at least two nitrogenous substances, 
 one of which was soluble in water alone, and the other in 
 water and alcohol. 
 
 Although several elaborate treatises have been published 
 on the brain-fats, our knowledge regarding them is still some- 
 
410 PHYSIOLOGICAL CHEMISTRY. 
 
 what vague. Boiling alcohol and ether extract a number of 
 distinct substances, but it is questionable how far they are all 
 entitled to be termed fats. Amongst the fatty matters de- 
 tected by Fremy in the brain, may be mentioned olein, oleic 
 and margaric acids, cerebric and oleo-phosphoric acids, and 
 cholesterin. Von Bibra maintains that the brain-fats consist 
 of cerebric acid and cholesterin, and of a series of fatty acids 
 possessing different properties and different fusing points ; 
 these fatty acids not even being the same in different brains 
 of one and the same species, and (as he conceives), undergoing 
 perpetual decomposition in the living organism, passing into 
 one another, and taking a share in the cerebral functions.* 
 
 * As the composition and very existence of several of the so-called fats of 
 the brain are doubtful, I think it better to notice them briefly in a note, in pre- 
 ference to introducing them into the text. 
 
 The cerebric acid of Frenay seems to be very nearly, if not quite, identical 
 with the cerebrin of Gobley, and the cerebrote of Couerbe. It is a white crys- 
 talline powder readily soluble in boiling, but almost insoluble in cold ether. 
 It is insoluble in cold, but is tolerably soluble in boiling alcohol. Its most 
 remarkable property is, that like starch it swells, but does not dissolve in boil- 
 ing water. 
 
 The following analyses prove not only the identity of cerebric acid and cere- 
 brin, but also the great similarity between this brain-fat and glycocholic acid, 
 a similarity which has led Schlossberger to the idea (see p. 176), that the latter 
 is the originator of the former. 
 
 Cerebric acid. Cerebrin. Glycocholic acid. 
 Fremy. Gobley. Strecker. 
 
 Carbon .... 668 66'8 67'1 
 
 Hydrogen 10'6 10'8 9-3 
 
 Nitrogen .... 2'4 2-9 2-9 
 
 Oxygen . . . . 19 '3 19 '6 20'6 
 
 Phosphorus. ... 0'9 0-4 
 
 Oleo-phosphoric acid (apparently the same substance as the eleencephole of 
 Couerbe), is described by Fremy as a yellow thick fluid like olein, insoluble in 
 water, but swelling a little in hot water (probably from a little retained cerebric 
 acid). It dissolves in ether and in hot alcohol -, and saponifies readily with the 
 alkalies and with other bases, forming insoluble salts. When boiled for a long 
 time with water or alcohol, it breaks up into olein and phosphoric acid a 
 separation that takes place much more quickly if a little mineral acid be added. 
 
 Gobley's investigations tend to show that very analogous, if not identical, 
 substances occur in the yelk of egg, and in the brain. In both of them he finds 
 a " matiere visqueuse " consisting of cholesterin, lecithin, and cerebrin, together 
 with other fats. 
 
THE BRAIN AND NERVOUS TISSUE. 411 
 
 In addition to the fats, W. Miiller, who has carefully 
 analysed the brain both of man and the ox, mentions the 
 following organic constituents of this tissue : creatine in small 
 quantity (in the human brain, but not in the brain of the ox), 
 a substance very similar to leucine (in the brain of the ox, 
 but not in that of man), lactic acid in considerable quantity, 
 inosite, a very little uric acid (in the brain of the ox), and 
 certain volatile acids, as acetic and formic acids. 
 
 Succinic acid, glycine, creatinine, urea, cystine and taurine 
 were sought for by Miiller in vain. 
 
 The mineral constituents of the human brain were found 
 by Breed to amount to O027 of the whole mass, and were 
 composed of 
 
 Phosphate of potash . . . 55-24 The 
 
 Phosphate of soda .... 22-93 " 
 
 Phosphate of iron . 1-23 
 
 Phosphate of lime . . . . 1*62 
 
 Phosphate of magnesia . . . 3-40 
 
 Chloride of sodium . . . 4-74 
 
 Sulphate of potash . . . 1-64 
 
 Free phosphoric acid . . . 9-15 
 
 Silica 0-42 
 
 According to Schlossberger, the ash of the grey matter has 
 a strongly alkaline, and that of the white a strongly acid 
 reaction. 
 
 The amount of water varies in different parts of the brain ; 
 the white portions being considerably poorer in water, and 
 richer in fat than the grey matter: indeed the water and 
 
 His lecithin is a neutral, uncrystallisable, viscid substance, which under the 
 influence of acids or alkalies, breaks up into olein, margaric, and glycero-phos- 
 phoric acids. 
 
 For further information on these questionable substances, I may refer to Von 
 Bibra's Vergleichende Untersuchungen iiber das Gehirn u. s. w., and to Schloss- 
 berger's Erster Versuch einer allgemeinen und vergleichenden Thier-chemie ; 
 II. Abtheilung : Das Nervengewebe. 
 
412 
 
 PHYSIOLOGICAL CHEMISTHY. 
 
 Action of 
 chemical 
 reagents 
 on the 
 nerves. 
 
 the fat in the different parts of the brain seem to stand in an 
 inverse ratio to one another ; thus the cortical substance of 
 the hemispheres contains from 84 to 88 of water and from 
 4*8 to 6-5f of fat, while the white substance of the corpus 
 callosum contains only from 63 to 70g of water, and from 
 15 to 21 g of fat. 
 
 The brain in the embryo, and in the young child, contains 
 more water than the brain in adult life ; and in old age the 
 quantity of water seems to be slightly augmented. 
 
 One peculiarity of the brain-fat is the large quantity of 
 phosphorus which it contains. The brain-fat jeven of the 
 same brain contains varying quantities of phosphorus, accord- 
 ing to the part from which it is extracted. Von Bibra found, 
 in the case of a man aged fifty-nine, that the fat from the 
 medulla oblongata contained 1'65, that of the cerebellum 
 1-83, and that of the optic thalami 1-54^ of phosphorus, the 
 mean for all the parts being 1*6 8--. From numerous observa- 
 tions, Von Bibra concludes (1) that the amount of phosphorus 
 in the brain-fat is very nearly the same in man, in other 
 mammals, and in birds; (2) that the phosphorus in the 
 brain-fat of insane persons does not deviate from the mean 
 amount ; and (3) that extreme old age does not modify the 
 quantity. 
 
 Some curious and interesting experiments have recently 
 been made (by Ecker, Kuhne, Birkner, and others), on the 
 stimulation of the nervous action by chemical reagents. 
 Motor nerves excite contractions in the muscles to which they 
 are distributed when stimulated by dilute caustic alkalies 
 (just as is the case with muscular fibre itself) ; muscular con- 
 tractions are also excited by touching the motor nerves with 
 mineral and organic acids, alkaline chlorides, glycerine, and 
 tannates of the alkalies ; but the solutions of these substances 
 must be much more concentrated than would be necessary 
 to cause muscular contraction if applied directly to muscle. 
 On the other hand chromic acid, sulphate of copper, neutral 
 
THE GLANDS A"ND THEIR JUICES. 413 
 
 and basic acetate of lead, lime-water, and ammonia, which 
 act energetically on muscular fibre, exert no influence in 
 stimulating the nerves ; while alcohol and creosote which 
 excite no action on the muscles, act energetically on the 
 nerves. It is, moreover, a remarkable fact, that curare or 
 woorali poison, and coneine, completely deaden the nerves to 
 any electrical or chemical stimuli, while the irritability of 
 muscular fibre remains unaffected by these reagents. Birkner * 
 has recently shown that many morbid conditions are induced 
 by an excess or deficiency of water on the nerves. 
 
 SECTION VII. THE GLANDS AND THEIR JUICES. 
 
 (305.) During the last few years, the glands and their ex- chemical 
 pressed juices have been submitted to careful chemical analysis t"nts"of 
 by Grorup-Besanez, Cloetta, and others. We shall briefly the glands, 
 state a few of the chief results. 
 
 Grorup-Besanez found leucine in the pancreas, spleen, thymus 
 gland, thyroid body, and (in small quantity) in the liver of 
 the ox. In both the pancreas and the spleen, he also found 
 a substance homologous to leucine (see p. 33). He failed in 
 detecting tyrosine in the thymus, thyroid, liver, kidneys, 
 lungs, and spleen, but once found a little in the pancreas. 
 He found hypoxanthine (in very small quantity) in the spleen, 
 thymus, and thyroid ; and uric acid only in the spleen. 
 
 Formic (see p. 11), acetic (see p. 11), succinic (see p. 16), 
 and lactic acids (see p. 22), were obtained from these glands. 
 
 Both Gorup-Besanez and Cloetta have found inosite in the 
 spleen, liver, kidneys, thymus, pancreas, and lungs. 
 
 Cloetta has found cystine in some cases, and taurine in 
 others, in the kidneys, and uric acid in the liver of the ox. 
 
 Scherer has found guanine in the pancreas of the ox. 
 
 * Das Wasscr der Nervcn in Physiologischcr und Tathologischcr Beziehung. 
 1858. 
 
414 PHYSIOLOGICAL CHEMISTRY. 
 
 The inorganic constituents of the liver, spleen, and certain 
 other glands have been carefully studied by Oidtmann in 
 men and women of various ages, and in several of the lower 
 animals. The following are some of his most important 
 results. 
 
 1. The amount of ash usually increases with the age of the 
 individual, while the amount of water decreases with the age. 
 
 2. In the liver the potash-salts preponderate over the soda- 
 salts, whereas in the spleen the latter preponderate. 
 
 3. Chlorine is present in only small quantity in the liver 
 and spleen, forming 2*5- of the ash in the former, and only 
 0-3 in the latter. 
 
 4. The quantity of phosphoric acid is large in the liver 
 (43-37 J of the ash) as compared with the spleen (18 to 27-g- 
 of the ash). 
 
 5. The quantity of lime is not great in either the liver or 
 the spleen, forming about 3-g- of the ash in the former, and 7-^ 
 in the latter; while the magnesia does not average more 
 than 1%. 
 
 6. In the spleen the iron is abundant, ranging from 7 to 
 16g- of the ash ; in the liver it amounts to 2*7g- of the ash. 
 
 7. Manganese, copper, and lead are commonly, but not 
 always, found both in the liver and spleen. 
 
BOOK III. 
 
 THE ZOO-CHEMICAL PROCESSES. 
 
BOOK III. 
 
 CHAPTER XVII. 
 
 THE METAMORPHOSES OF THE TISSUES. 
 
 (306.) THE reader who has carefully studied the preceding 
 pages cannot have failed to see that four great groups of 
 substances are essential to the well-being of the human 
 organism. 
 
 These groups are : - The esscn. 
 
 1. The protein-bodies and their derivatives. h^thf 10 
 
 2. The fats. animal me ~ 
 
 tamor- 
 
 3. The carbo-hydrates, e.g. sugar, starch, &c. phoses. 
 
 4. The mineral constituents of the body. 
 
 (307.) The most superficial glance at the mode in which Albumen, 
 albumen presents itself in the animal body and at the extent 
 in which it occurs suffices to show that it must be one of the 
 most important substances to the organism. We meet with 
 it most abundantly in the blood and other animal juices that 
 are most subservient to nutrition ; under slightly modified 
 forms we find it as blood-fibrin, syntonin, casein, globulin, 
 hsematoglobulin, &c. ; and, either in its original state or in 
 the form of some of its modifications, in the muscles, nerves, 
 and other comparatively solid structures of the body. We 
 further find the animal germ deposited in a fluid rich in 
 albumen (and possibly casein), and likewise containing salts, 
 fat, and sugar in comparatively small quantities, and there 
 can be no doubt that it is from the albuminous matters that 
 the germ derives the materials requisite for its nourishment. 
 
 E E 
 
418 PHYSIOLOGICAL CHEMISTRY. 
 
 We further see that the young of the mammalia are provided 
 with a nutrient fluid the milk of which, besides fat and 
 sugar, the chief constituent is casein, a protein-body rich in 
 salts, and which, with the exception of a smaller amount of 
 sulphur, contains the same elements as albumen, and arranged 
 in the same proportions ; at the period therefore when the 
 growth of the gelatigenous, non-albuminous, tissues (such as 
 the bones and skin) require the largest supplies, the body is 
 supported by the same class of organic compounds which 
 occur in the nutrient fluid the blood. Hence it is obvious 
 that the gelatigenous and elastic tissues, and in short all the 
 nitrogenous tissues, must be primarily derived from albumen 
 or casein : and since most of the solid tissues contain far more 
 oxygen than the protein-bodies it is most probable that the 
 oxygen introduced into the blood by the lungs takes an 
 active share in converting the raw material, albumen, into the 
 different textures ; but of the individual steps of the process 
 we know little. We are not in a position to decide with 
 positive ' certainty whether blood- fibrin constitutes the ne- 
 cessary transition-stage from albumen to chondrin and gela- 
 tigenous tissue ; nor do we know whether chondrin must 
 always precede glutin in the formation of the connective 
 tissue, skin, &c. It is easy to construct formulae showing how 
 these and other metamorphoses may occur ; for example, by 
 the addition of a certain number of atoms of oxygen, and the 
 abstraction of certain atoms of water and carbonic acid, we 
 may often construct several formulae, all showing how the 
 substance or tissue may be converted into other substances, 
 and this very facility has led many good chemists to rash 
 conclusions; and indeed when we find that the concurrence 
 of several different substances is necessary for the accom- 
 plishment of many processes, as, for instance, that nutrient 
 matter requires the presence of fat to be properly digested, 
 and that not a single cell or fibre can be formed without the 
 simultaneous presence of a protein-body (probably fibrin), 
 
THE METAMORPHOSES OF THE TISSUES. 419 
 
 fat, and phosphates, we can hardly suppose that such formulae 
 as those to which we have referred can express the true and 
 complete process of metamorphosis. That the metamorphic 
 actions going on in the animal economy are of a complex 
 character and require the simultaneous presence of two or 
 more substances is a view which is further supported (1) by 
 the facts that wherever albuminous matters occur, non- 
 nitrogenous carbo-hydrates are always present, although often 
 only in small quantity, and that wherever fats are formed or 
 decomposed, we always meet with albuminous matters ; and 
 (2) by the analogous processes which we can induce in dead 
 organic matter, as, for instance, in the process of fermentation, 
 where we see that one organic substance cannot co-exist with 
 another undergoing the process of metamorphosis without 
 being implicated in an analogous molecular movement. All, 
 however, that we really positively know regarding the nitro- 
 genous metamorphic products of the tissues is that the 
 different phases under which they appear in the organism 
 must be essentially dependent upon the inspired oxygen which 
 gives rise to the numerous modifications which the molecules 
 of the albuminous matters undergo before their final change 
 into urea and similar substances.* 
 
 * In connection with the action of the inspired oxygen upon the albumen of 
 the blood, I may allude to the interesting observations recently made by Von 
 Gorup-Besanez (Ann. d. Ch. u. Pharm. vol. ex. pp. 86107), on the effect 
 produced by ozonised air on solutions of albumen and casein. Besides modify- 
 ing its colour (rendering it red by incident and green by transmitted light), it 
 produced, in an albuminous solution, fibrin-like coagula, which disappeared on 
 prolonged action of the ozone ; and there finally remained in the fluid a material 
 which was no longer coagulable by heat nor was precipitated by mineral or or- 
 ganic acids, by the ordinary metallic salts (except by basic acetate of lead), or 
 by yellow prussiate of potash, but was thrown down in flakes by alcohol, and 
 consequently very closely resembled the albumen-peptone formed during 
 digestion. 
 
 A solution of casein exposed for a certain time to the action of ozone became 
 converted into an apparently albuminous fluid, being coagulable by heat, and 
 no longer precipitable by acetic acid ; and by prolonged action the further 
 changes ensued which have been already noticed as occurring in albumen. 
 
 Ozone was found to produce no apparent action on fibrin or gelatin. 
 E E 2 
 
420 PHYSIOLOGICAL CHEMISTRY. 
 
 The fats. (308.) The second great group includes the fats, whose 
 various uses in the chemistry of the animal body have been 
 already noticed (see p. 79). We have there shown that in 
 addition to their mechanical uses, they take an active part 
 in the chemistry of digestion and in all the processes by 
 which the fluid nutrient substances are converted into tissues, 
 and have likewise there and in other passages drawn at- 
 tention to the fact that no animal eell or fibre is formed 
 independently of the presence of fat. In connection with 
 the importance of fat in the animal economy, we may adduce 
 the well-known fact that the introduction of fat into the 
 body (either as food or medicine) predisposes the organism 
 to the formation of cells ; a cell-formation of this kind how- 
 ever requires the concurrence o albuminous substances for 
 the construction of the cell-walls. When the organism does 
 not find in the food sufficient materials to form the investing 
 membrane of the fat-cells, it borrows from the muscular fibre 
 the necessary protein-substance ; and when this source can 
 no longer be drawn from, the fat begins to accumulate in the 
 blood and other fluids.* From these facts and from certain 
 microscopic observations a theory of cell-formation has been 
 propounded, according to which each cell is primarily formed 
 by the deposition of a thin layer of a protein-body around a 
 minute vesicle of fat. We are not prepared fully to support 
 this apparently simple explanation of the origin of a cell ; 
 but this at least is certain, that fat is always to" be found in all 
 highly cellular organs (as, for example, the brain and liver), 
 and in all tissues during the process of their development ; pus 
 and certain cancerous growths are rich in fat ; the hair-bulbs 
 present an active formation of new cells, and we find them 
 imbedded in the sebaceous glands ; the chyle, which always 
 abounds in cells in various stages of formation, always contains 
 
 * These results were deduced by Persoz and Boussingault from a series of 
 observations on animals that were being fattened. (Ann. de Chim. et de Phys. 
 3rd ser. vol. xiv. p. 413435.) 
 
THE METAMORPHOSES OF THE TISSUES. 421 
 
 much fat ; the germ in the egg is surrounded by the fatty 
 yelk-fluid; and numerous fat-globules are found in the 
 muscular and other foetal tissues. 
 
 We are ignorant of the exact chemical changes which the 
 fat in the blood undergoes ; but it seems almost certain that 
 there is a separation into base and fatty acid, and that the 
 latter undergoes a gradual oxidation, but whether the decom- 
 position is due to the alkali of the blood or to some other 
 cause is not known. The fatty acid may either be thoroughly 
 oxidised into carbonic acid and water, or may be converted 
 into formic, acetic, and butyric acids, and in these forms be 
 eliminated by the skin. By this oxidation the fats contribute 
 materially to the support of the animal temperature, and have 
 consequently been termed "heat-formers' 1 or "respiratory 
 food." 
 
 But the deposition of a considerable quantity of a peculiar 
 modification of fat in the nervous tissue, shows that in this 
 case, at all events, the fat must not be regarded as a mere 
 material for combustion ; the chemical peculiarities of the 
 nerve-fats, their different fusion-points, and their varied dis- 
 tribution in different parts of the brain, tend to show that they 
 play an important part in connection with the function of the 
 nervous system generally, a view that is further supported by 
 the fact that when, either from starvation or disease, the fat 
 has disappeared from almost all -the other organs, it remains 
 unaffected in the nervous tissue. 
 
 We have already shown (see p. 27), that there is reason to 
 believe that one fatty substance, oleic acid, contributes to the 
 formation of the resinous acids of the bile ; the individual steps 
 of this probable metamorphosis cannot, however, be traced. 
 
 We have previously noticed the much-disputed question 
 regarding the formation of fat within the organism, so far as 
 the carbo-hydrates are concerned (see p. 77), but we have 
 still to consider whether fat may not be formed from other 
 substances, namely, the protein-bodies. 
 
 X E 3 
 
422 PHYSIOLOGICAL CHEMISTRY. 
 
 Although our attempts to convert protein-bodies into true 
 fat by chemical means have hitherto proved unsuccessful, 
 Liebig has shown that it is not only possible, but very pro- 
 bable, that these substances may be converted into fat in the 
 animal body. In the putrefactive process, and in the gradual 
 oxidation of albuminous substances, butyric and other fatty 
 acids are developed; and the experiments of Quain and 
 Virchow on the conversion of muscular tissue into adipocire, 
 support the view that the muscular fibre is converted into 
 ammoniacal soaps, or compounds of fatty acids with ammonia. 
 Moreover, in fatty degeneration of muscles, the true substance 
 of the fibrillae disappears, and is replaced by fat. 
 
 A number of remarkable experiments have been made by R. 
 Wagner, Bonders, Middeldorpf, Michaelis, Sehrader, Husson, 
 F. W. Burdach, and others, on the introduction of various nitro- 
 genous animal matters in the abdominal cavity, and on the me- 
 tamorphoses which they undergo after being retained there for 
 several (four to eight) weeks. Crystalline lenses, portions of 
 coagulated albumen, and similar non-fatty protein-bodies, have 
 been introduced into the abdominal cavities of pigeons and 
 other birds, and after a lapse of time varying from twenty-five 
 to fifty-four days, were found to be wholly changed, and to 
 yield, in addition to mere traces of nitrogenous matters, a 
 much larger proportion of fat than the substance had originally 
 contained ; and similar experiments with nearly similar results 
 were made with tendons, cartilages, and bones. To prove, 
 however, that the fat was formed in these cases from the in- 
 troduced protein-body, and that it was not a result of infiltra- 
 tion from the surrounding fluid, corresponding experiments 
 were made in which the protein-body was so enclosed (in 
 collodion, gutta percha, glass tubes, &c.), as to cut off every 
 possible supply of fat from without, and it was then found 
 that when the animal juices were entirely cut off, the pro- 
 tein-bodies were not metamorphosed into fat, nor indeed did 
 they undergo any essential alteration ; hence, if these bodies 
 
THE METAMORPHOSES OF THE TISSUES. 423 
 
 are. actually converted into fat within the animal body, the 
 free access of animal juices is at all events indispensable to 
 the process. It was likewise found that porous vegetable 
 substances,, such as wood and elder-pith, when introduced 
 like the albuminous matters, into the abdominal cavity, 
 yielded very similar results, a yellow fatty exudation being 
 deposited around them, and the fat having been imbibed 
 through the intercellular spaces into the interior: and here 
 a metamorphosis into fat was obviously out of the question. 
 
 As this method of investigation did not seem likely to 
 decide the question of the formation of fat from the protein- 
 bodies, Burdach has attempted another method which ma}^ 
 if carried more fully out, lead to satisfactory results. Some 
 experiments which he has made on the eggs of a snail 
 (Linnaeus stagnalis\ during their development, appear to 
 indicate that during this process there is a considerable 
 augmentation of fat in the embryo, which must have arisen 
 from the decomposition of albuminous matters.* The sub- 
 ject, however, requires further investigation. 
 
 (309.) The substances forming the third great group, the The carbo- 
 carbo-hydrates, are in many points of view so closely allied to Jy 
 the fats, that in speaking of them we shall have occasion to 
 make some additional remarks regarding the uses of the latter 
 in the animal economy. If we except cellulose, which is 
 found in the mantles of certain tunicata/(see p. 93), there 
 are only four carbo-hydrates occurring in the animal body, 
 namely, glycogen (or the substance forming liver-sugar), 
 glycose or grape-sugar, lactine or milk-sugar, and inosite or 
 muscle-sugar ; and these are for the most part found in those 
 animal fluids which are especially concerned in the nutrition 
 and metamorphosis (tfte formation and disintegration) of the 
 tissues. The fact of our finding sugar in the blood, in the 
 
 * A full account of Burdach's experiments (and indeed of almost all the in- 
 vestigations bearing on the subject) may be found in Hippert and Lehmann's 
 Zoochemie, 1858, p. 544 546. 
 
 E 4 
 
424 PHYSIOLOGICAL CHEMISTRY. 
 
 lymph, in the chyle, in both the white and yelk of egg, 
 and in the milk, is, in itself, an evidence that this substance 
 takes an active part in many animal processes, while a 
 further indication of its importance is afforded by the fact of 
 its being formed and stored up in the liver even in animals 
 whose food contains no sugar. 
 
 Since the sugars do not, in the normal condition, pass into 
 the excretions, but are oxidised in the blood into carbonic acid 
 and water as ultimate products, they must, like the fats, con- 
 tribute materially to the support of the animal heat ; but this 
 is by no means their only use. If they served only to generate 
 heat, we should expect to find the saccharine matter (whether 
 glycose or milk-sugar) diminish, or even wholly disappear in 
 the egg during the oxidation which accompanies the process 
 of development ; but in reality an augmentation of sugar is 
 found to take place during incubation. We shall endeavour 
 now to indicate some of these uses. In the imperfect oxi- 
 dation of the carbo-hydrates various acids (lactic, acetic, 
 butyric, &c.) are evolved, of which one of the most important 
 is lactic acid, which, in addition to its occurring in other 
 parts of the organism, is found abundantly in the small in- 
 testine, as far as the middle of the ileum (see p. 186), notwith- 
 standing the neutralising action of the pancreatic fluid and 
 bile. It is probably of service here, in contributing to dis- 
 solve any nitrogenous matters that may have escaped the 
 action of the gastric juice ; but it is likewise an essential 
 means of promoting the absorption of the soluble constituents 
 of the chyle; for, from the experiments of Jolly* and of 
 Graham f (especially the latter), it has been proved that an 
 acidified albuminous fluid is much more diffusible than an 
 alkaline albuminous fluid. Wherever; therefore, an alkaline 
 and an acid albuminous fluid are separated by a membrane, 
 the main current of the interchanging fluids will be directed 
 
 * Zeits. f. rat. Med. vol. vii. pp. 83147. 
 f PhiL Trans, for 1850, p. 1. 
 
THE METAMORPHOSES OF THE TISSUES. 425 
 
 towards the alkaline side, and hence the acid of the small 
 intestine must essentially aid in promoting the absorption of 
 its contents. In this way the carbo-hydrates, through their 
 acid products of metamorphosis, play an important part in 
 the process of chylification ; and we thus probably get a clue 
 to the therapeutic use of acids in various disorders of the chylo- 
 poietic organs. 
 
 Liebig has specially drawn the attention of physiologists to Formation 
 the peculiar grouping of the alkali and the acid in the animal phosphates, 
 economy, and to the necessary results of this arrangement. 
 If the carbo-hydrates were directly consumed, without the 
 intervention of the lactic and other acids, an acid reaction 
 could never be generated in the bodies of herbivorous 
 animals, or, in other words, no acid phosphates could be 
 formed ; for the ashes of plants (if we except certain seeds) 
 always having an alkaline reaction, the food of the herbivora 
 would (if it were not for the acids formed from the carbo- 
 hydrates) only yield fluids with an alkaline reaction. The 
 carbo-hydrates thus serve, by the acid products of their 
 metamorphosis, to distribute the phosphoric acid amongst 
 the bases ; and thus to restore the acid salts and acidly 
 reacting fluids. By this distribution of the acids and alkalies, 
 effete matters are most rapidly removed from the tissues and 
 transferred to the blood, where they are employed in main- 
 taining the animal heat, or are entirely removed by the 
 kidneys or skin, while at the same time, and by the same 
 means, deleterious matters are hindered from passing into 
 the tissues from the blood. 
 
 Again, sugar exerts a considerable solvent action on the Sugar as a 
 carbonate and phosphate of lime ; and there is little doubt 
 that the well-known augmentation of the lime-salts in the 
 embryo of the bird during incubation is due to this action of 
 the sugar upon the egg-shell. 
 
 We have already (see p. 77) noticed the experiments which Formation 
 seem to demonstrate the convertibility of the carbo-hydrates g ug a r . r 
 
426 PHYSIOLOGICAL CHEMISTRY. 
 
 into fat within the animal body ; but we do not know in what 
 part of the system the change is effected, nor do we under- 
 stand the exact chemical nature of the change.* This much, 
 however, is certain, that the deposition of fat within the 
 animal body indicates a deficient supply of oxygen, and 
 shows that the amount inspired was insufficient to allow the 
 complete combustion of the sugar into its final products, 
 viz. carbonic acid and water. 
 
 Further uses of sugar and of the lactic acid derived from it 
 will be shortly noticed, in their connexion with the next great 
 group, the inorganic salts, which we now proceed to consider. 
 Mineral (310.) Any doubt that might have existed regarding the 
 
 tucnts" necessity of the presence of these substances for the support of 
 animal life, must have been completely removed by the expe- 
 riments which have been made by various French physiologists, 
 showing that animals died in a comparatively short time, when 
 fed upon substances containing no salts, although otherwise 
 nutritious. 
 
 Antago- Although the latest researches of Du Bois Reymond (see 
 
 adcTa^d P* ^04) r ^nder it probable that Liebig has attached a very 
 alkaline undue weight to the electric phenomena induced by the 
 separation of the acid and alkaline fluids, certain results of 
 unquestionable importance arise from this antagonism, which 
 seem to be widely diffused through the body. Thus the 
 blood, chyle, lymph, and transudations are always alkaline ; 
 so also are the saliva, and (less strongly) the bile and pan- 
 creatic fluid ; the gastric juice is strongly acid, as also are the 
 muscular juice after exercise (see p. 405), and the parenchy- 
 
 * Liebig has suggested two different ways in which the formation of fat from 
 sugar may be explained. It may in the one case be analogous with various 
 fermentations, each atom of sugar being decomposed into carbonic acid, and into 
 a substance poor in oxygen ; or in the other case the sugar may undergo a pro- 
 cess analogous with butyric fermentation, in which the hydrogen is in part 
 abstracted from the carbo-hydrate and carbonic acid escapes, while a substance 
 poor in oxygen remains in the form of a fatty acid. The formation of butyric 
 acid from sugar is explained by the formula C 12 H 12 O 12 = 4H + 4CO 2 + 
 C 8 H 7 3 .HO. 
 
THE METAMORPHOSES OF THE TISSUES. 427 
 
 matous fluid of the spleen, thymus gland, smooth muscles, 
 liver, and suprarenal capsules. A similar antagonism (in a 
 slight degree) seems to exist between the yelk and white of 
 the egg, and probably between the blood-cells and the plasma. 
 Now wherever a fluid exhibits an acid reaction, it is found 
 to contain acid phosphates, and when the acid reaction is not Phos- 
 distinctly marked, phosphoric acid is found either conju- pu1 
 gated or simply combined with casein, hsematoglobulin, or 
 glycerine. The earthy phosphates are, moreover, brought 
 into solution by free acids to a greater extent than could have 
 been effected by albumen or casein alone (see p. 127) ; and 
 in this way we can account for the large quantities of these 
 phosphates which are present in the ash of the animal fluids ; 
 for the discoveries of Graham show that by simple physical 
 laws, an acid fluid may be separated from the alkaline blood, 
 or an acid phosphate may be separated from a neutral phos- 
 phate and permeate the coats of the vessels. 
 
 It was first shown by Liebig, in his investigation of the 
 muscular juice, and has been subsequently confirmed by 
 C. Schmidt, Lehmann, and others, that those fluids which are 
 very rich in phosphates, and which exhibit an acid reaction, 
 contain only a small amount of soda-salts, but are very 
 rich in potash-compounds ; while the blood is rich in soda- 
 salts and very deficient in potash-compounds. Graham's ex- Potash- 
 periments show that there is a considerable difference in the 
 diffusibility of potash and soda salts, but we have not as yet 
 sufficient data clearly to elucidate the physical reason of this 
 grouping of the acid phosphates and potash-compounds ; nor 
 can we tell with anything like certainty what purposes, in 
 relation to metamorphosis generally, are accomplished by the 
 simultaneous presence of the free acid, the phosphates, and 
 the potash-compounds, in these animal fluids. 
 
 We likewise find phosphates in parts and tissues of the 
 body independently of the presence of a free acid or the 
 formation of acid salts. All histogenetic substances (see 
 
428 PHYSIOLOGICAL CHEMISTRY. 
 
 p. 127) are so closely combined with phosphates (chiefly 
 phosphate of lime), that they remain associated during the so- 
 lution and the subsequent re-precipitation of these substances ; 
 and the ground- work of developed tissues (such as muscle, con- 
 nective tissue, lung, and liver) always contains in its ash a con- 
 siderable quantity of phosphates in the form of 1 equivalent of 
 fluid to 1 of base, whence we may infer that acid phosphates 
 existed in the recent tissue, or that a portion of the phos- 
 phoric acid had been combined with organic matter. We 
 have already seen (p. 386) that all plastic exudations from 
 the blood must contain a certain amount of phosphates ; 
 and C. Schmidt has shown that, in the Mollusca, a definite 
 amount of these salts is required to supply the first basis 
 for new tissue, even in organs which subsequently ex- 
 hibit an excess of carbonate of lime.* A further and a 
 very convincing proof of the share taken by the phos- 
 phates in the formation and functions of the tissues is 
 afforded by the fact noticed by Liebig, that although 
 the herbivorous animals take up a very small quantity of 
 phosphates in their food, and although their blood is very 
 poor in these salts, their tissues and organs contain as large 
 a proportion of phosphates as the corresponding parts of the 
 Carnivora. 
 
 Alkalinity The alkalinity of the blood is not dependent on the 
 blood presence of a free alkali, but is due (see p. 107) to certain 
 
 compounds of the alkalies (soda almost entirely) with albu- 
 minous substances, and with carbonic and phosphoric acids. 
 The albumen of the blood-serum is combined with soda in two 
 different proportions, one of these albuminates being rich 
 and the other poor in soda ; these two albuminates of soda 
 (one of which is a neutral and the other a basic compound) 
 are mixed together in the blood in variable proportions, 
 and it is only in disease that free albumen is found in this 
 fluid. 
 
 * Zur vergleich. Physiol. der wirbell. Thicre, 1845, pp. 5660. 
 
THE METAMORPHOSES OF THE TISSUES. 429 
 
 As a consequence of the unstable character of these com- 
 binations, the acids which are formed in or enter the blood 
 are at once saturated, and, owing to the abundant supply of 
 acid fluids * with which the blood is surrounded, the alkalinity 
 of the liquor sanguinis would rapidly be destroyed if the 
 newly formed salts were not readily and quickly decomposed 
 into carbonates, in addition to being in part removed un- 
 changed from the blood. 
 
 We have now to consider the purposes which the alkalies Uses of 
 accomplish in the blood. The main purpose doubtless is, 
 the promotion of the oxidation of the constituents of the blood - 
 blood, oxygen being simultaneously present in that fluid. It 
 is universally known that the tendency of oxygen to combine 
 with certain elements is enormously increased by the pre- 
 sence of alkalies ; and numerous experiments show the 
 necessity that the organic constituents of the blood should 
 be subjected to a process of gradual oxidation by the 
 simultaneous presence of oxygen and the loosely combined 
 alkalies in the blood. In order to obtain a clear idea uf the 
 most probable action of this process, we will notice the con- 
 stituents of the blood individually, and consider their rela- 
 tions when exposed to the simultaneous influence of free or 
 loosely combined alkalies and of oxygen, at the temperature 
 of the human body. 
 
 We will begin with the organic acids which freely and in 
 considerable quantity transude into the blood. Solutions of the 
 salts formed by these acids with alkalies very readily undergo 
 decomposition even if there is little air admitted, provided 
 there be an excess of the alkali. Solutions previously colour- 
 less become brown ; low fungoid growths are developed, and 
 after a time products of the oxidation of the organic acids 
 (usually other acids) are generated. The alkali-salts of 
 gallic and pyrogallic acids oxidise so rapidly that they have 
 
 * According to Liebig, the lactic acid yielded by the muscular tissue alone 
 is more than sufficient to neutralise all the alkaline fluids of the body. 
 
430 PHYSIOLOGICAL CHEMISTRY. 
 
 been proposed by Liebig as eudiometric agents. Wohler's 
 discovery, that the alkali-salts of the organic acids are con- 
 verted in the system into carbonates (see p. 327), is therefore 
 nothing extraordinary, and certainly does not prove that the 
 animal body possesses any special oxidising power ; the means 
 by which organic acids in combination with an alkali are 
 consumed being precisely the same both within and without 
 the organism. 
 
 Action of The rapid consumption of sugar in the blood is easily 
 sugar. accounted for, when we consider that sugar in association with 
 an alkali can abstract oxygen from many metallic oxides, such 
 as oxide of copper (Trommer's test), oxide of silver, &c. The 
 combined experiments of Meyer and Bernard further eluci- 
 date the mode in which the sugar* is destroyed ; Meyer * having 
 discovered that carbonic oxide is not only easily absorbed by 
 the blood, but that it displaces an equal volume of oxygen, 
 and thus renders it poor in this constituent ; while Bernard 
 has discovered that after the absorption of carbonic oxide by 
 the blood, the sugar sometimes accumulates to such an 
 extent in that fluid as to appear unchanged in the urine. 
 The sugar is not directly oxidised into carbonic acid and 
 water, but is first probably converted into lactic acid and 
 some of the fatty acids ; possibly the succinic acid which 
 has been occasionally met with may also originate from sugar. 
 The experiments that have been made on the oxidising 
 agency of the alkalies on the fats and fatty acids are not so 
 striking in their results as those we have already mentioned. 
 There can be no doubt that the alkalies in the blood, even if 
 in the state of carbonates, are- actively engaged in the saponi- 
 fication of the fats, but whether they co-operate with the 
 oxygen of the blood, so as to oxidise the fatty acids that are 
 liberated, is not positively certain. 
 
 The researches of Chevreul and Scherer show that hsematin 
 
 * Moyer's experiments were of course made on blood that had been ab- 
 stracted from the body. 
 
THE METAMORPHOSES OF THE TISSUES. 431 
 
 when dissolved in alkalies undergoes an immediate change if 
 oxygen be present, becoming converted into a colourless body. 
 The exact nature of this metamorphosis is not known. 
 
 It cannot be doubted that the albuminous matters of the 
 blood undergo a gradual oxidation before they can be em- 
 ployed in the formation or restoration of the tissues, but we 
 are not able to determine the extent to which the alkalies 
 influence their oxidation and further metamorphosis. 
 
 Lehmann has directed attention to the fact that the purely Oxidising 
 chemical character of the above change is evidenced by the the blood, 
 definite limitation of the oxidising power of the blood. That 
 this power, although very intense, is very limited, is demon- 
 strated by experiments which clearly show that if more than a 
 certain quantity of sugar or of a vegetable acid in combination 
 with an alkali is introduced into the blood, the excess passes 
 unchanged into the excretions. Thus the experiments of 
 Lehmann and of Ranke show that salicin is sometimes only 
 oxidised in the organism into salicylous acid, and on other 
 occasions into salicylic acid, the different result apparently 
 depending partly on difference of constitution in the persons 
 on whom the experiments were made, and partly on the 
 quantities that were administered. On the other hand, the 
 action of the alkali in connection with the oxidation of the 
 blood-constituents must not be overrated, for we find from 
 the experiments of Parkes, Buchheim, and Clare, that the in- 
 troduction of an alkali into the stomach, or even its injection 
 into the blood, is not necessarily followed by any augmenta- 
 tion of sulphuric acid in the urine sufficient to demonstrate 
 that there had been an increased oxidation of the albuminates ; 
 nor in cases of artificially induced saccharine urine does the 
 administration or injection of alkalies or their carbonates 
 cause a disappearance or even a necessary diminution of the 
 sugar.* The fact noticed by Gr. v. Liebig, that a very active 
 
 * Although Lehmann's experiments (which are fully described in pp. 233 
 235 of the third volume of my translation of his Physiological Chemistry ") 
 fully bear out the statement contained in the text, nnd seem to overthrow 
 
432 PHYSIOLOGICAL CHEMISTRY. 
 
 process of oxidation goes on in the acidly reacting muscles, 
 seems to indicate that the presence of an alkali is not an 
 essentially necessary condition of oxidation. 
 
 Important as the oxidising process carried on in the blood 
 doubtless is, we must recollect that many isolated facts have 
 been noticed which are apparently opposed to the view of the 
 process being perfectly general. Various phenomena seem 
 to indicate -the co-existence of an oxidising and a de-oxidi- 
 sing process ; as, for instance, the formation of substances so 
 rich in unoxidised sulphur as taurine and cystine, and of 
 others so poor in oxygen as cholesterin, hypoxanthine, 
 &c. Kanke's * experiments show that the animal organism 
 exerts a positively reducing or de-oxidising power upon 
 indigo, ordinary indigo-blue being converted, when it re- 
 appears in the urine, into sub-oxide of isatin, or reduced 
 indigo. 
 
 Chloride There are strong reasons for believing that chloride of 
 
 sodium is an active factor in the metamorphoses of the 
 animal tissues. We find it in a tolerably fixed and definite 
 quantity in most of the animal juices which are specially 
 concerned in nutrition, the quantity in each case being wholly 
 independent of the nature of the food or of the amount taken 
 with the food ; while the quantity in the excretions, and 
 especially in the urine, corresponds very closely with the 
 quantity ingested with the food. Even if we attach little 
 weight to the instinct which leads certain domestic animals 
 
 o 
 
 eagerly to lick up the salt placed before them, and which 
 induces wild animals (buffaloes for instance) to travel long 
 distances in search of salt-licks (as they are termed), or to 
 the corresponding craving exhibited by certain African tribes 
 for salt ; the experiments of Boussingault distinctly show 
 that the use of salt with ordinary food (unless that food 
 
 Mialhe's view that diabetes is due to a deficiency of alkali in the blood, I feel 
 bound to state that I have on several occasions prescribed alkaline carbonates 
 with great temporary benefit in cases of diabetes. 
 * Journ. f. pr. Ch. voL Ivi. p. 17. 
 
THE METAMORPHOSES OF THE TISSUES. 433 
 
 contains a certain quantity) is indispensably requisite for 
 the healthy condition of domesticated animals ; Boussingault 
 made simultaneous experiments upon two sets of cows (each 
 consisting of three), one of which he fed for a month on 
 food with which salt had been mixed, and the other on 
 fodder containing no salt ; and he found that, although the 
 salt produced no effect upon the formation of flesh or fat, or 
 upon the quantity of milk, there was a very marked dif- 
 ference in the external appearance and activity of the two 
 sets of animals ; those which had received no salt presenting 
 a less smooth and shining coat, and being in thoroughly bad 
 condition. The importance of this mineral constituent of 
 the body is further shown by the fact, that in cases of star- 
 vation or of insufficient nourishment, and in certain acute 
 diseases (especially pneumonia), the separation of common 
 salt by the urine soon ceases, lest the blood should lose its 
 due proportion. 
 
 The following are some of the ways in which chloride of 
 sodium co-operates in the metamorphosis of the tissues. 
 
 Some protein-compounds, as for example albumen and 
 casein, when they have been freed as much as possible from 
 alkalies and salts, are soluble in a solution of chloride of 
 sodium ; whilst others, as for instance glutin and syntonin, 
 are precipitated from their acid solutions by the addition of a 
 solution of this salt, of less strength even than 4-g- . Hence 
 the presence of chloride of sodium in such fluids as blood, 
 exudations, &c., may serve under different circumstances to 
 promote both the separation and the solution of albuminous 
 substances. 
 
 Urea and grape-sugar are almost the only substances with 
 which chloride of sodium combines chemically ; and Liebig 
 was led by this fact to very ingenious views regarding the 
 function of salt in the metamorphosis of matter. Urea pro- 
 bably combines with chloride of sodium far more intimately 
 than we should be led to infer from their ready separation 
 
 F F 
 
434 PHYSIOLOGICAL CHEMISTRY. 
 
 by recrystallisation in water ; thus urea is only imperfectly 
 separated by nitric acid from concentrated urine if much 
 salt is present ; and again, it occurs in association with salt 
 even in fluids in which we should scarcely expect it, as, for 
 instance, in the fluids of the eye and in the sweat. Hence 
 Liebig conjectures that the absence of urea as well as of com- 
 mon salt in the muscular juice, and the passage of urea into 
 the circulation, and subsequently into the urine, are due to the 
 fact of the urea existing in the organism in a state of combi- 
 nation with chloride of sodium. Again, diabetic urine always 
 contains the sugar and salt compound to which we have already 
 alluded, in addition to free sugar ; indeed it not unfrequently 
 happens that the only saccharine crystals which we can succeed 
 in obtaining from diabetic uri&e consist of this compound. 
 Now since the saliva and pancreatic fluid, whose function it is 
 to convert starch into sugar, and the gastric and intestinal 
 juices, contain a considerable quantity of chloride of sodium, 
 it seems very probable that the sugar is absorbed from the 
 intestines in this state of combination ; and this probability 
 is much increased by the observation of Bernard, that sugar 
 when injected into the subcutaneous cellular tissue appears 
 more rapidly in the urine when it is mixed with chloride of 
 sodium, than when it is injected pure or mixed with sulphate 
 of soda. 
 
 The chloride of sodium must also undergo decomposition 
 in the animal organism. It as impossible to decide with cer- 
 tainty whether the free hydrochloric acid of the gastric juice 
 arises from the chloride of sodium, or from the more easily 
 decomposed chloride of calcium ; but at all events, in the 
 blood of herbivorous animals it must be decomposed by the 
 preponderating quantity of the salts of potash which is 
 derived from their food ; for in every 4 parts of alkaline car- 
 bonate in their blood-serum there are at least 3 parts of car- 
 bonate of soda, and only 1 part of carbonate of potash ; while 
 in the muscular juice both of carnivorous and herbivorous 
 animals chloride of potassium is almost solely found. This 
 
THE METAMORPHOSES OF THE TISSUES. 435 
 
 fact, for the knowledge of which we are indebted to Liebig, 
 shows, on the one hand, that the chloride of sodium in the 
 blood must necessarily undergo an interchange of constituents 
 with the carbonate and phosphate of potash, and on the other 
 hand, that nature has assigned very different functions in the 
 animal organism to the alkalies which are otherwise so similar 
 in a chemical point of view. 
 
 Liebig is of opinion that the constancy of the amount of 
 chloride of sodium present in the blood is an essential point 
 in connection with the process of absorption ; and when we 
 consider that the fluid contents of the intestinal canal are far 
 less dense than the blood, and that the kidneys possess the 
 property of immediately carrying off any excess of water that 
 may have entered the blood, we cannot doubt that important 
 endosmotic relations are established by the fixed concentra- 
 tion of the blood. 
 
 Lastly, chloride of sodium seems to exert a decided influ- 
 ence upon the development of cells both in secretions and 
 exudations. Mucus, which consists almost entirely of a 
 humid mass of cells, contains a far larger quantity of chloride 
 of sodium than any other animal fluid ; the cartilages, which 
 are highly cellular, contain more of this constituent than any 
 other solid tissue ; the synovial fluid and the sweat also con- 
 tain it abundantly. Exudations in which pus-corpuscles or 
 cancer-cells are developed are rich in chloride of sodium ; and 
 in pneumonia the chloride of sodium which is retained in the 
 body (and can scarcely be detected in the urine) accumulates 
 chiefly in the pulmonary exudation, which is generally trans- 
 formed into cytoid corpuscles (grey hepatisation), and partly 
 in the saliva (Beale). We are entirely ignorant of the mode 
 in which this salt acts in the development of cells. 
 
 With respect to the other mineral constituents which occur 
 in the animal body, we need only refer to what has been 
 already stated (see pp. 125139), since they play a less 
 active and important part in the general function of life. 
 
 F F 2 
 
436 PHYSIOLOGICAL CHEMISTRY. 
 
 CHAPTER XVIII. 
 DIGESTION. 
 
 (311.) As we have already (in the second part of this volume) 
 treated of the different juices which take part in the digestive 
 process, and have attempted to determine the function 
 which each of them performs, we shall now proceed, on the 
 assumption that the reader has an ordinary knowledge of 
 the structural anatomy of the intestinal tract, to notice the 
 changes which are impressed by the digestive process on the 
 different constituents of food ; namely, the mineral con- 
 stituents, the carbo-hydrates, the fats, and the albuminates. 
 
 Digestion Mineral substances* usually undergo comparatively little 
 of mineral J J 
 
 substances, change during the digestive process, and often enter the 
 lacteals without undergoing any changes whatever. Carbo- 
 nates and free bases are converted in the stomach into 
 chlorides or lactates, according as hydrochloric or lactic is the 
 preponderating acid in the gastric juice; sulphates are re- 
 duced in the intestinal canal to sulphides ; the earthy phos- 
 phates are soluble in the acids of the gastric juice, and 
 phosphate of lime is also partially soluble in carbonic acid, 
 sugar, chloride of sodium, &c. The magnesian salts appear 
 to undergo a certain degree of decomposition, so that a 
 greater proportion of acid than of base is absorbed ; some of 
 the soda or potash of the intestinal fluid probably abstracting 
 a portion of the acid from the magnesian salt. Chloride of 
 
 * In the consideration of the mineral substances I have included a few 
 which have no right to be regarded as constituents of food, but which are of 
 interest in relation to therapeutics. 
 
DIGESTION. 437 
 
 magnesium, magnesia, and its basic carbonate (3MgO.C0 2 .HO 
 -f MgO.HO), are all converted in the intestinal canal into 
 the bicarbonate, most of which reappears in the excrements.* 
 According both to Frerichs f and Bernard, metallic iron and 
 its peroxide are soluble in the gastric juice, iron filings being 
 converted (according to the latter observer) into protoxide 
 and peroxide of iron in the stomachs of living animals. 
 These salts must undergo further changes whose nature is 
 not understood, from coming in contact with phosphates and 
 other substances in the stomach. 
 
 The nitrates, borates, chlorates, and arseniates of the alka- 
 lies pass unchanged from the intestine into the blood. 
 
 As the salts of ammonia, after their ingestion, are found 
 to pass unchanged into the urine, they must enter the blood 
 unchanged. 
 
 Salts of the oxide of silver enter into combination with 
 organic matters whenever they have an opportunity of doing 
 so. They do this even in the mouth, and likewise in the 
 stomach, notwithstanding the presence of hydrochloric acid ; 
 and in the latter case it is not until the albuminates (or 
 peptones) are saturated that any chloride of silver is formed. 
 These albuminates of silver are soluble both in acid and 
 alkaline fluids, and it is in this form of combination that silver 
 enters the blood.J 
 
 The changes which the salts of mercury undergo in the 
 organism have been carefully studied by several competent 
 observers. Mialhe, who has paid much attention to the 
 chemical action of remedies, maintains that calomel is con- 
 verted by the alkaline chlorides of the stomach into corrosive 
 
 * See Guleke, De vi magnesia, etc. Dorpati, 1854; and Kerkorius, De mag- 
 nesias ejusque salium mutationibus. Dorpati, 1855. 
 
 f The references to Frerichs in this chapter always apply to his celebrated 
 article on digestion, in Wagner's Handworterbuch der Physiologic. 
 
 J Buchheim, Lehrbuch d. Arzneimittellehre, pp. 242244. I cannot too 
 highly recommend this work to those who wish to study the chemical action 
 of remedies, and the changes which they undergo in the organism. 
 
 F F 3 
 
438 PHYSIOLOGICAL CHEMISTRY. 
 
 sublimate, because if we heat calomel with strong solutions 
 of chloride of sodium or chloride of ammonium, some of the 
 calomel becomes converted into corrosive sublimate ; but 
 Von Oettingen and Buchheim have clearly shown that this 
 change does not take place in dilute solutions, and that 
 even when four times as much chloride of sodium was added 
 to the gastric juice as is actually present, not a trace of corro- 
 sive sublimate was formed. At the temperature of the body, 
 Von Oettingen found that calomel rapidly combined with 
 albumen. Corrosive sublimate also enters into combination 
 with albuminous substances, but the nature of the compound 
 is not definitely known; most chemists regard it as an 
 albuminate of oxide of mercury. n 
 
 The changes which sulphur undergoes in the organism 
 have been specially studied by Buchheim and Krause ; but 
 they have not come to any very decided conclusion. They 
 find that it is not dissolved by the fatty me.tters present in 
 the intestines, and are of opinion that it h probably con- 
 verted into an alkaline sulphide. 
 
 Digestion (312.) The carbo-hydrates next claim ou.r attention, viz. 
 
 hydrates, the different kinds of sugar, starch, gum, and cellulose. 
 
 Sugar. Of all the varieties of sugar, grape-sugar or glycose is the 
 
 most important, partly from its frequent occurrence in ordi- 
 nary articles of food (fruits, honey, &c.), and partly because 
 it is the form of sugar into which other carbo-hydrates 
 (starch, &c.) are transformed before they are fitted for ab- 
 sorption or for any further changes. 
 
 From the experiments of Lehmann, Uhle, and Von Becker 
 on rabbits and other animals, it appears that when sugar is 
 introduced in large quantity through the mouth into the 
 stomach, it is very rapidly diffused over a large extent of 
 the intestinal tract, and is especially abundant in the coecum ; 
 about an hour after its ingestion the small intestine is found to 
 contain a thin and often perfectly limpid saccharine solution, 
 which more or less rapidly disappears from the bowels 
 according to its degree of concentration. 
 
DIGESTION. 439 
 
 The absorption of sugar from the intestine is a very slow 
 and gradual process ; and it is only rarely that we can detect 
 absorbed sugar in the chyle or portal blood. When, how- 
 ever, very large quantities of sugar are introduced into the 
 stomach, it may be detected in the blood, where it some- 
 times amounts to 06^-, and any excess above this quantity is 
 at once carried off by the kidneys. 
 
 From the fact of our finding an unusual quantity of gly- 
 cose in the blood under these circumstances, there can be 
 no doubt that a portion (probably far the largest part) is ab- 
 sorbed in an unchanged condition ; some, however, of the 
 sugar is always converted into acids. When sugar was in- 
 jected into the stomachs of rabbits, which were killed an hour 
 afterwards, the contents of the duodenum and jejunum were 
 found to have a strong acid reaction, which was less marked, 
 but still very distinct in the ileum, while the contents of the 
 ccecum always presented a very strong acid reaction. This 
 acid reaction depends chiefly on the formation of lactic 
 acid from the sugar, but in the ccecum butyric acid prepon- 
 derates over the lactic. From the experiments of Heintz and 
 Van den Broek, it appears probable that the bile takes an 
 active part in the conversion of sugar into lactic acid ; others 
 have held that the pancreatic fluid is concerned in this 
 change. That it is not effected by either the intestinal juice 
 or the mucus of the intestine, seems to be proved by experi- 
 ments made by Funke, who introduced a solution of glycose 
 into a tied loop of gut, and found on examination, two, three, 
 or four hours afterwards, that most of the fluid was removed, 
 but that the remaining portion never exhibited an acid 
 reaction. 
 
 From the fact that sugar begins to accumulate in the 
 blood within a short time (from one and a half to two hours) 
 after its ingestion, we may infer that it is for the most part 
 absorbed by the capillaries; but as we always find small 
 quantities also in the chyle, when much sugar has been taken, 
 
 F F 4 
 
440 PHYSIOLOGICAL CHEMISTRY. 
 
 a portion of it would seem to have been taken up by the 
 lacteals. 
 
 From numerous observations instituted by Von Becker on 
 the absorption of sugar, the following facts seem well esta- 
 blished : 
 
 Laws of its (l.) The quantity of the absorbed sugar is altogether 
 independent of the length of the loop of gut in which it is 
 enclosed, or of the superficial extent of the absorbing surface. 
 
 (2.) While it is generally believed that the absorption of 
 the intestinal contents proceeds with a rapidity proportional 
 in some degree to the dilution of the solutions contained in 
 the intestine, Von Becker found that for saccharine solutions 
 precisely the opposite rule held good; for it appeared that 
 when equally large quantities of solutions of different 
 strengths were injected, the absorption stood in a direct ratio 
 to the concentration. 
 
 The comparative difficulty with which sugar is absorbed, as 
 compared, for example, with various salts, is explained on purely 
 physical grounds by the endosmotic experiments of Graham 
 and of Jolly. It has been found, for instance, by Graham, 
 that sugar has less than half the diffusibility of chloride of 
 of sodium, for while 58*7 parts of salt are diffused, only 26*6 
 parts of sugar are diffused under precisely the same con- 
 ditions. 
 
 These facts seem to explain how it is that the sugar, which 
 is usually in a very dilute form in the intestine, is so slowly 
 absorbed and so rapidly diffused over a large extent of 
 intestinal surface. 
 
 It will readily be seen from the preceding observations, that 
 in consequence of the amount of the absorbed sugar varying 
 with the concentration, it is by no means easy to determine 
 how much sugar an animal of given weight can absorb in a 
 given time. If a very weak solution be introduced into the 
 intestines it is absorbed with extreme slowness; if, on the 
 other hand, a concentrated solution is thrown into the intes- 
 
DIGESTION. 441 
 
 tine, a large quantity of water is (by endosmosis) abstracted 
 from the blood, and the gut becomes so over-distended with 
 watery fluid, as to interfere very materially with the re- 
 spiratory actions, and often even to cause death. 
 
 Cane-sugar, according to the observations of Lehmann and 
 Von Becker (which are however opposed to those of Frerichs), 
 is for the most part converted before it reaches the middle of 
 the jejunum into glycose ; it was only rarely indeed that Yon 
 Becker could trace cane-sugar to this spot, even when large 
 quantities of this substance had been introduced into the 
 stomachs of animals (cats and rabbits). Since neither saliva, 
 nor gastric juice, nor intestinal fluid is able to effect this 
 change, we must conclude that it is induced by the presence 
 of some of the other contents of the intestine, setting up a 
 catalytic or fermenting action. That the conversion takes 
 place in the intestinal canal, and not within the circulation, is 
 obvious from the experiments which have been made by 
 various observers (English, French, and German), which 
 show that cane-sugar injected into the blood is carried away 
 unchanged in the urine. 
 
 Sugar of milk behaves in the intestinal canal in precisely 
 the same manner as glycose. It is very rapidly distributed 
 over the whole of the small intestines, and can be traced, in 
 about an hour after it has been swallowed, as far as the 
 coecum ; it leaves an intensely acid reaction in the jejunum 
 and ileum, which remains for three or four hours after the 
 ingestion of the sugar. 
 
 (313.) As an object of food, starch is by far the most Starch, 
 important of the carbo-hydrates. We know that in con- 
 sequence of its insolubility it must undergo a preliminary 
 metamorphosis in order to be absorbed, and that it must be 
 converted into dextrine and glycose with perhaps a little lactic 
 acid, the saliva (see p. 151) and the pancreatic juice (see 
 p. 181) being the chief means by which the re-arrangement 
 of the atoms t)f starch is effected. Powerful as is the action 
 
442 PHYSIOLOGICAL CHEMISTRY. 
 
 of the saliva upon boiled starch, its effect upon raw starch, 
 especially when we consider for how short a time the starch 
 and the saliva are being intermingled, must be very slight. 
 The starch probably for the most part enters unchanged into 
 the stomach, where it is generally believed that the gastric 
 juice rather impedes than promotes any further action of the 
 saliva upon it. The latest observations on this subject, by 
 Drs. F. Gr. Smith and Brown-Sequard *, strongly tend, how- 
 ever, to show that the gastric juice in the stomach does not 
 impede the conversion of starch into sugar. It is probably in 
 the duodenum, after the pancreatic fluid has come in contact 
 with it, that its active metamorphosis occurs ; and, as we have 
 seen in p. 185, the intestinal juice afterwards completes the 
 metamorphosis of any starch that has escaped the effects of 
 the saliva and pancreatic fluid. 
 
 The conversion of starch into sugar is a gradual process. 
 The starch-granules become softened externally, and as they 
 dissolve become converted into dextrine and sugar. Individual 
 lamellae peel off and become detached, and then rapidly 
 undergo disintegration ; and the farther the starch passes 
 onwards along the small intestines so much the smaller are 
 the granules. 
 
 The enormous development of the coecum in herbivorous 
 animals, and the peculiar glands which abound in the Pro- 
 cessus vermiformis seem to indicate that the amylaceous 
 matters are here submitted to a new metamorphic secretion, 
 but we have no certain proofs that this is the case. As facts 
 to a certain degree supporting the view that starch is acted 
 upon in the ccecum, we may mention that Frerichs found 
 butyric acid especially abundant in this part of the intestine ; 
 and that Funke found that a solution of sugar injected into 
 the coecum becomes rapidly converted into an acid fluid. 
 
 Dextrine, the first product of the decomposition of starch, 
 
 * Journ. de Physiologie, 1858,'vol. i. p. 158. 
 
DIGESTION. 443 
 
 is so rapidly converted into sugar that we only rarely find it 
 in the intestine, and then only in small quantity. 
 
 (314.) Gum is a carbo-hydrate concerning whose uses in Gum. 
 the organism there has been much difference of opinion. 
 We may suppose either (1) that it is converted into sugar 
 and then absorbed, or (2) that it is absorbed directly and 
 without change, or (3) that it is not at all absorbed, and is 
 consequently entirely eliminated with the solid excrements. 
 Numerous experiments, macle independently by Frerichs, 
 Lehmann, and Blondlot, show that it is extremely improbable 
 that even a small portion of gum is converted into sugar 
 during digestion; if therefore gum be subservient to the 
 purposes of life we must assume that it is absorbed in an un- 
 changed state either by the blood-vessels or the lacteals ; for 
 there is no reason to suppose that it is likely to be converted 
 into any substance except sugar, into which it is actually 
 changed by prolonged digestion in dilute mineral acids. 
 Boussingault caused a duck to swallow 50 grammes (about an 
 ounce and a half) of gum arabic, and in the course of nine hours 
 46 grammes were recovered from the excrements. Lehmann 
 daily injected 10 grammes of dissolved gum arabic into the 
 stomach of a rabbit which was fed on cabbage leaves. Grum 
 was found abundantly in the excrements, but not a trace 
 could be detected in the urine ; and when at the end of three 
 days the animal was killed, four hours after its last dose of 
 gum (10 grammes), no trace of gum could be discovered 
 either in the chyle or in the blood. Hammond (see p. 341) 
 found from experiments on his own person, (1) that gum is alto- 
 gether incapable of assimilation, and therefore possesses no 
 calorifacient or nutritive power whatever, but is, on the 
 contrary, a source of irritation to the digestive organs ; and 
 (2) that in consequence of the above fact, ^the solids of the 
 urine during a purely gum and water diet, are entirely 
 derived from the waste of the tissues of the body, arid the 
 carbon exhaled by the lungs from the consumption of its fat. 
 
444 PHYSIOLOGICAL CHEMISTRY. 
 
 Busch, in a series of observations on a woman with an artificial 
 anus a little below the duodenum, found that most of it 
 passed unchanged through the fistulous opening. From a re- 
 view of these experiments we must either arrive at Hammond's 
 conclusion, that gum is altogether incapable of absorption,, or 
 else that so small a quantity passes into the animal fluids as 
 to be incapable of detection ; and in favour of this latter 
 view it must be admitted, (1) that physical experiments prove 
 that gum penetrates through animal membranes, although 
 much less readily than many other substances *, and (2) that 
 the ordinary tests for the detection of gum (silicate of 
 potash, borax, and sulphate of iron) are not sufficiently 
 sensitive, when applied to a mixture of organic bodies, to 
 indicate the presence of a very small quantity of that substance. 
 CeUulose. (315.) Cellulose, or the substance of the vegetable cell, is 
 one of those substances which resist the action of all the 
 known digestive fluids ; and hence all those substances which 
 essentially consist of cellulose re-appear unchanged in the 
 excrements both of herbivorous and omnivorous animals; 
 but certain chemical and anatomical facts render it not im- 
 probable that in some animals, as for instance in the beaver, 
 and possibly in caterpillars, the cellulose may be converted 
 into sugar.f 
 
 It is probable, from the researches of Donders and others, 
 that the thin films of cellulose which invest young vegetable 
 cells are dissolved in the intestines of the herbivora. 
 
 * The diffusibility of gum is only half that of glycose, and four or five times 
 less than that of chloride of sodium ; while on the other hand it is more than 
 four times greater than that of albumen. 
 
 f As the stomach, intestines, and especially the coecum of the beaver, are often 
 filled to distension with fragments of wood and bark, with no detectible inter- 
 mixture of soluble nutrient substances, we can hardly avoid the supposition 
 that the digestive fluids of this animal are capable of exerting a metamorphic 
 action upon cellulose ; and in support of this view it may be mentioned, that 
 in the beaver the salivary glands and the pancreas are enormously developed ; 
 and there is a large gastric gland peculiar to this animal, which may have 
 something to do with the digestion of cellulose. 
 
DIGESTION. 445 
 
 (316.) The route by which the fats are conducted from the Fats. 
 food into the blood is more easily traced by the microscope 
 than by chemical tests. Experiments on artificial digestion 
 show that neither the saliva nor the gastric juice exerts any 
 influence on the fats, but when fatty tissue is taken into the 
 stomach, the connective tissue and the cell-walls are digested, 
 and the liberated fat collects in drops of considerable size or in 
 semi-fluid masses. In the duodenum these drops or masses 
 disappear, and from this point downwards the fat in the 
 intestinal canal is found to be more and more finely com- 
 minuted in proportion as the alkalinity of the intestinal 
 contents becomes more decided.* 
 
 Although the fat is mainly absorbed by the lacteals, a 
 portion of it passes directly into the blood, as is shown by 
 the observations of Bruck, who detected fat-granules among 
 the blood-corpuscles of the capillaries of the villi after the 
 free use of fatty food ; and under similar circumstances the 
 blood of the portal vein also contains more fat than usual. 
 
 There has been much doubt and obscurity until com- 
 paratively lately as to the physical conditions under which 
 fats which are insoluble in water, are made to penetrate the 
 membranous walls of the intestine which are charged with 
 watery fluids. We have already seen (p. 174) that the bile is 
 the chief, if not the only agent in the absorption of the fats ; 
 and this view is confirmed by the fact that in animals with 
 biliary fistulse, by which the bile is discharged externally, 
 extremely little fat is absorbed ; and Busch similarly found, 
 in the case already referred to, that if fat (butter or cod- 
 liver oil) was injected through the fistulous opening into the 
 
 * Busch's observations on the woman with artificial anus seem to warrant the 
 view that there is a causal connection between the alkalinity and the minute- 
 ness of the disintegration of the fat. For, on giving her cod-liver oil on an 
 empty stomach, the digestive fluids which escaped through the fistula some- 
 times had an alkaline and sometimes (most frequently) an acid reaction ; and 
 it was noticed that the fatty particles were extremely minute whenever the 
 reaction was alkaline. 
 
446 PHYSIOLOGICAL CHEMISTRY. 
 
 jejunum, into which, it must be recollected, none of the 
 contents of the duodenum made their way, most of it re- 
 appeared unabsorbed in the faeces. 
 
 Alcohol; (317.) Although in 1838 Dr. Percy clearly proved that 
 
 if alcohol were freely administered, a portion of it (or at all 
 events of an inflammable substance closely resembling it), 
 passed into the urine and the fluid in the cerebral ventricles, 
 the first endeavour to trace the various changes which this 
 fluid undergoes in the system, seems to have been made in 
 1847, by Bouchardat and Sandras. They found that alcohol 
 underwent no change in the primce vice, and that it was taken 
 up unchanged by the veins of the stomach and intestines, but 
 not by the lacteals. In the respired air they detected small 
 quantities of alcohol, but were of opinion that it was elimi- 
 nated by the organs of excretion in an oxidised form, as 
 water, carbonic acid, and especially as acetic acid. Their 
 observations are confirmed by Frerichs. The discrepancy 
 between their experiments and those of Dr. Percy may be 
 probably due to the fact, that it is only when an excessive 
 quantity of alcohol is introduced into the system that any 
 traces of it can be detected in the excretions. 
 
 Duchek, in two cases out of three of dogs that were killed 
 when in a state of intoxication, detected aldehyde (C 4 H 3 O.HO, 
 see note to p. 19) in the blood, but could find no alcohol. 
 The oxidation necessary to convert the alcohol into aldehyde 
 could not have taken place in the stomach, because the 
 oxidising action within that viscus is not stronger than in 
 ordinary atmospheric air, and no aldehyde was found in it. 
 Since alcohol when injected into the veins causes coagulation 
 of the blood, but does not produce that effect when introduced 
 into the stomach ; and since, further, aldehyde when injected 
 into the blood does not cause the blood to coagulate, but oc- 
 casions intoxication ; he infers, that alcohol is converted into 
 aldehyde as it enters the absorbent vessels. After narcosis 
 from aldehyde, acetic and oxalic acids were found in the 
 
DIGESTION. 447 
 
 blood, while during the intoxication no acetic acid could be 
 detected. 
 
 Buchheim, a higher authority on a matter of this kind, 
 disputes the accuracy of Duchek's * view that the alcohol is 
 converted into aldehyde, which thus becomes the actual in- 
 toxicating agent. 
 
 He observes f, that it is extremely improbable that if 
 alcohol in its passage into the blood becomes so readily con- 
 verted into aldehyde, a substance so very prone to oxidation 
 as aldehyde should remain for a comparatively long time un- 
 changed in the blood, instead of almost immediately under- 
 going further decomposition. " In fact," he observes, " Duchek 
 has adduced no sufficient proof of the presence of aldehyde in 
 the blood, for the odour, which other experimenters failed to 
 detect, affords very uncertain evidence (especially when it is 
 masked by the peculiar smell of freshly-drawn blood) ; and the 
 reduction of an ammoniacal solution of silver, which Duchek 
 observed to be produced by the blood of dogs to which alcohol 
 had been given, is no test of the presence of aldehyde, for the 
 distillate of a healthy dog's blood produces the same effect, i 
 Further, the fact that aldehyde produces in the body the 
 same phenomena as alcohol, is no proof of the point in ques- 
 tion. Indeed, we possess at present no means of determin- 
 ing with certainty, whether it be alcohol or aldehyde that is 
 present in the blood in these cases ; and most probably the 
 blood contains comparatively large quantities of undecomposed 
 spirit with traces of aldehyde." Buchheim failed in detecting 
 the acetic and oxalic acids which had been noticed by the 
 
 * Prag. Vierteljahrsschrift, u. s. w., 1853, vol. iii. p. 104. 
 
 f Lehrbuch der Arzneimittellehre, p. 103. 
 
 \ Masing, De Mutationibus spiritus vini in corpus ingesti. Diss. Inaug. 
 Dorpat. 1854. 
 
 Strauch, De Demonstratione spiritns vini in corpus ingesti. Diss. Inaug. 
 Dorpat. 1852. (See also Buchheim, Ueber die Nachweisung des Alkohols 
 bei gerichtlichen Untersuchungen, in Deutsche Zeitschrift fur Staatsarzneikunde, 
 1854.) 
 
448 PHYSIOLOGICAL CHEMISTRY. 
 
 previous observers, but determined with certainty the presence 
 of alcohol in the condensed respiratory products, and in the 
 urine, both in the case of dogs and in that of two men ; 
 Massing and Strauch also detected it in the urine. Ether, 
 he believes, undergoes the same changes in the blood as 
 alcohol ; while chloroform (which has been detected unchanged 
 in the blood), is. finally decomposed into formic and hydro- 
 chloric acids. 
 
 (318.) We now proceed to the consideration of a group of 
 bodies of which the protein-compounds are the main represen- 
 tatives, but which likewise includes not only their derivatives, 
 chondrin and glutin, but a number of other matters, such as 
 emulsin, the poison of serpents, curarine (or woorali), and 
 various poisons of infectious or contagious diseases. All these 
 bodies must not only be dissolved, but must undergo an 
 essential change in the intestinal canal before they can be ab- 
 sorbed. We have already seen that the albuminous matters are 
 not merely dissolved by the gastric juice, but are converted into 
 matters termed peptones (see pp. 108, 163), which, although 
 similar in their ultimate composition to the substances from 
 which they were derived, differ from them in several essential 
 points, amongst which may be especially mentioned their 
 greater solubility in water, the readiness with which they pass 
 through a filter, their being no longer coagulable, and (which 
 is of the greatest importance in relation to digestion) their 
 ready diffusibility through animal membranes. These pep- 
 tones can be formed either by natural or artificial digestion 
 Peptones, from the gastric juice. They form a group of substances, 
 which have the following properties in common : They are 
 white, amorphous, easily pulverisable when dry, are insoluble 
 in alcohol, but dissolve readily in water, the aqueous solution 
 having an acid reaction, and not being coagulable by heat or 
 by acids, but being precipitable by tannic acid and by 
 corrosive sublimate, but not by the metallic salts generally. 
 Ferrocyanide of potassium (a most general test for this class 
 
DIGESTION. 449 
 
 of bodies) merely induces a slight turbidity when added 
 to a solution acidified by acetic acid ; and Millon's test (see 
 p. 104) and even chromic acid produce no apparent change. 
 The peptones form soluble compounds with the alkalies 
 and the alkaline earths. The different peptones, although 
 agreeing in the above common characters, are not perfectly 
 identical. 
 
 Meissner * has recently discovered a class of bodies which 
 are always formed simultaneously with the peptones, by the 
 action of the gastric juice on albuminates. These bodies, to 
 which he has assigned the name of parapeptones, are distin- Parapep- 
 guishedjrom the peptones in being precipitated from the acid t( 
 digestive mixture in the stomach by the addition of a little 
 alkali. (The alkali must not be added in sufficient quantity 
 to neutralise the acid fluid.) These parapeptones, though 
 differing slightly from one another, have the following pro- 
 perties in common. They are insoluble in water, but form 
 easily soluble compounds with acids, alkalies, and alkaline 
 earths. Alcohol has no effect upon the solutions of these 
 compounds, but a mixture of alcohol and ether throws down 
 white flakes. Millon's test gives the same reactions with the 
 parapeptones as with the albuminates ; while they contrast 
 with the peptones in this respect, they coincide in forming 
 pure blue solutions with sulphate of copper and potash, 
 while the unchanged protein-bodies form with these substances 
 bluish violet solutions. From these and other reactions which 
 Meissner has described we should infer that the parapeptones 
 are more nearly related than the peptones to the protein- 
 bodies from which each derives its origin ; and we might 
 hence be inclined to infer that the peptones are formed from 
 the parapeptones, and that the latter are merely imperfect 
 products of gastric digestion. Meissner however shows very 
 clearly that this is not the case, and that the albuminates are 
 
 * Zeitsch. f. rat. Med. 1859. 3rd Ser. vol. vii. pp. 116, 
 
 a a 
 
450 PHYSIOLOGICAL CHEMISTRY. 
 
 apparently simultaneously decomposed (or broken up) into 
 peptones and parapeptones, which latter are not further 
 changed by the gastric juice. From several experiments he 
 concludes that the protein-bodies are broken up into peptones 
 and parapeptones, which stand to one another in nearly the 
 ratio of 2:1. Although the gastric juice cannot affect 
 parapeptones, they are converted into peptones (or very 
 similar bodies) by the action of pancreatic juice. 
 
 We are indebted to Mulder for the knowledge (and he 
 has been confirmed by Meis'sner) that gelatin and the gelati- 
 genous tissues do not yield peptones. Meissner found that a 
 solution of pure gelatin .in gastric juice contained neither 
 peptone nor parapeptone, but gelatinised on cooling, and 
 behaved precisely as it would have done if dissolved in dilute 
 hydrochloric acid, being in fact altogether unchanged. Busch, 
 however, obtained very different results. On giving gelatin 
 (calves' foot jelly) to his patient, the fluid discharged from 
 the fistulous opening contained only one-third of the gelatin 
 that had been administered, and this portion had lost its pro- 
 perty of coagulation. 
 
 Emnlsin. (319.) Emulsin seems to be thoroughly metamorphosed in 
 
 the intestinal canal, for if this substance and amygdalin are 
 simultaneously introduced into the stomach or into the blood, 
 decomposition is set up in the amygdalin (which taken alone 
 is harmless) and prussic acid is formed, which destroys the 
 life of the animal on which the experiment is performed. 
 Lehmann allowed rabbits to eat sweet almonds (which contain 
 emulsin), and injected amygdalin into the jugular vein one, 
 two, four, and six hours after they had fed, and the animals 
 remained perfectly well. He then reversed the experiment 
 and injected emulsin into the vein while he introduced a 
 solution of amygdalin into the stomach of the animal, and 
 in this case symptoms of poisoning by prussic acid very soon 
 presented themselves. The only way of accounting for these 
 results is by supposing either that the emulsin is so completely 
 
DIGESTION. 451 
 
 changed in the primce vice that it can no longer set up 
 decomposition in the amygdalin, or that the emulsin is inca- 
 pable of being absorbed. If the latter were the case it would 
 pass off unchanged by the excrements, but Lehmann found 
 that on mixing amygdalin with the excrements of a rabbit 
 which had been fed for forty-eight hours on sweet almonds 
 there was no trace of any solution of prussic acid. Indeed 
 no decomposition of the amygdalin was induced even by the 
 contents of this animal's ccecum. Kolliker and H. Miiller have 
 repeated and confirmed Lehmann's experiments. 
 
 Curarine (or woorali) and the other poisons which we have Curarine. 
 mentioned seem to be changed in a similar manner in the 
 intestinal canal, for otherwise they would be as poisonous 
 when taken into the stomach as they are when introduced 
 directly into the blood. 
 
 (320.) The gastric juice is the chief but not the only agent The vari- 
 that exerts a metamorphic effect on the protein-bodies. The i solvent" 
 quantity of gastric juice which is secreted is usually not fluids - 
 sufficient to dissolve and metamorphose the amount of 
 albuminous matters which is necessary for the due nutrition 
 of the body ; hence a considerable portion of this class of 
 bodies passes unchanged from the stomach into the small 
 intestines, where it is acted upon by the intestinal fluid and 
 probably also by the pancreatic juice.* Any protein-bodies 
 
 * The true action of the pancreatic juice on the albuminates is not definitely 
 determined. While Freriehs, and Bidder and Schmidt deny that the pancreatic 
 juice has any action on these bodies, Corvisart in 1857 published a memoir 
 " On the Digestion of Nitrogenous Alimentary Bodies by the Pancreas," which 
 has led to much discussion. In this memoir he relates a number of experiments 
 upon animals, the results of which led him to the conclusion that the pancreatic 
 juice, whether alkaline, neutral, or acid, possessed a true digestive action, and 
 converted the protein-bodies into peptones. Keferstein and Hallwachs (Gb't- 
 tingen Nachrichten, 1858, No. 14 ), directly deny the correctness of his conclu- 
 sions. Meissner (op. cit.) finds that the pancreatic juice is able to digest albu- 
 minous substances, and that it transforms them into bodies closely allied 
 to the peptones, provided the fluid that is used (namely, the infusion of the 
 pancreas) be prepared from animals which were killed while in the act of 
 digestion, and provided also that the fluid has an acid reaction. The former of 
 
 G G 2 
 
452 PHYSIOLOaiCAL CHEMISTEY. 
 
 that may make their- way into the large intestine most 
 probably escape without further change in the excrement. 
 
 The casein of milk is precipitated in the stomach in the 
 form of flakes and is then gradually dissolved, but if a con- 
 siderable quantity of milk was given to Busch's patient a 
 portion of the casein passed, without being coagulated, out of 
 the fistulous opening. Soluble albumen on the other hand 
 appears, from experiments on artificial digestion, not to be 
 coagulated, but to be converted directly into peptones and 
 parapeptones. Busch found that on giving his patient un- 
 cooked white of egg a portion was absorbed in the stomach 
 and the part of small intestine above the fistula while a portion 
 (about one-third) escaped unchanged. 
 
 Busch made numerous observations on the action of the 
 intestinal juice on coagulated albumen, flesh, starch, &c., 
 but as they for the most part coincide with those of Frerichs, 
 and Bidder and Schmidt it is unnecessary to notice them. 
 
 (321.) The protein-bodies after their conversion into 
 peptones are for the most part absorbed by the lacteals ; a 
 
 these conditions accords with Corvisart's own observation, the latter is opposed 
 to it. In his latest publication (L'Union Med. 1859, No. 87), while noticing 
 the criticisms to which his views have been exposed, he gives the following as 
 his conclusions. (1.) That the mixed liquid poured into the duodenum (namely 
 the bile and the pancreatic and intestinal juices) digests albumen when the 
 gastric juice is altogether excluded. (2.) That coagulated albumen can be 
 digested in large quantity by the infusion of pancreas alone ; and (3.) That 
 the quantity of albumen which is dissolved is almost the same (notwithstanding 
 Meissner's assertion) whether the fluid is acid, neutral, or alkaline, and that 
 in point of fact the mixture of fluids in the duodenum is sometimes acid, some- 
 times neutral, and sometimes alkaline, and that, notwithstanding their difference 
 of reaction, the effect on albumen is much the same. Corvisart further holds 
 that the pancreas is not in full action till about five or six hours after a meal ; 
 in short, not till the stomach has almost completed its work. Experiments by 
 Dr. Brinton and Professor Harley in part confirm Corvisart's views. The 
 latest investigations are those of Skrebitzki (conducted under the superintend- 
 ence of Bidder and Schmidt), who comes to the conclusion, from a series of 
 careful experiments, that the solvent action of the pancreatic juice is precisely 
 equal to the solvent power of an equal quantity of water containing as much 
 alkali as is usually found in this secretion. 
 
DIGESTION. 453 
 
 portion of them is however taken up directly by the capillaries 
 of the villi ; and some authorities of great weight, amongst 
 whom we may mention Frerichs and Bonders, believe that 
 most probably the absorption of the peptones commences in 
 the stomach. 
 
 (322.) In several points of view a knowledge of the daily Daily 
 amount of the secreted digestive fluids is important. The 
 results of the investigations of Bidder and Schmidt on the fluids, 
 lower animals show that the amount of the juice which flows 
 into the intestinal canal in the twenty-four hours -is far 
 greater than is commonly supposed, and amounts to almost 
 the sixth part of the whole weight of the body, and subse- 
 quent observations on the case of Catherine Kutt (see p. 162) 
 show that probably their estimate of the amount of the 
 gastric juice is too low. 
 
 If we apply to the case of an adult man the quantitative 
 relations of the individual secretions obtained by Bidder and 
 Schmidt for animals, it follows from their calculations that an 
 adult man weighing 64 kilogrammes (or about 10 stone), will 
 secrete in the twenty-four hours, 
 
 Kil. Lbs. Grammes. Drachms. 
 
 Saliva amounting to 1-6 (= 3'5 ) containing 15 (= 3'8 ) of solid matter. 
 Bile 1-6 ( = 3-5 ) 80 ( = 20'5 ) 
 
 Gastric juice 6'4 (=14-1) 192 ( = 49-3 ) 
 
 Pancreatic juice 0'2 (=0-44) 20 (=5-1) 
 
 Intestinal juice 0-2 (=0'44) 3 (0=0'76) 
 
 According to these numbers, the quantity of fluid which is 
 effused daily into the intestinal canal amounts to 10 kilo- 
 grammes, or more than 22 Ibs., and is larger than the whole 
 amount of the blood contained in the body ; as farther, it only 
 contains 310 grammes (or 3 !--) of solid constituents, it seems 
 especially designed to rinse and purify the dissolved food. 
 
 (323.) Busch found, in the series of experiments to which Busch's 
 we have so frequently referred, that the nature of the food 
 had a very marked effect upon the amount of the secreted worn an 
 
 digestive fluids. Animal food caused a much more copious in the 
 
 jejunum, 
 c o 3 J J 
 
454 PHYSIOLOGICAL CHEMISTRY. 
 
 flow of digestive fluids through the fistulous opening than 
 vegetable food ; and the most abundant effusion was noticed 
 to, follow the ingestion of fat. Busch found that, at the lowest 
 estimate yielded by his observations, the amount of digestive 
 fluids effused into the upper part of the intestinal canal in 
 twenty-four hours is one-seventeenth of the weight of the 
 body. 
 
 The experiments that have been made with a view to de- 
 termine the amount of nutriment that can be absorbed by 
 the intestinal canal in a given time, are not of a very satis- 
 factory character. Lehmann is of opinion that a man can 
 absorb in one hour about 430 grammes (or about 22 ounces) 
 of sugar, 45 grammes (or about an ounce and a half ) of fat, 
 and 100 grammes (or rather more than 3 ounces) of protein- 
 substances. 
 
 A chapter on ' ' The Digestion," would obviously be imper- 
 fect if it included no notice of the digestibility of the different 
 ordinary articles of food. Unfortunately, our knowledge on 
 this subject is very imperfect, the experiments which have 
 been made being in part unsatisfactory in the mode in which 
 they were devised, and in part, giving absolutely contradictory 
 results. The experiments of Grosse, who possessed the power 
 of vomiting at will, and who thus brought up food which had 
 remained for different lengths of time in the stomach, and 
 even the much more valuable observations of Beaumont on 
 Alexis St. Martin, are unsatisfactory in the following respects. 
 (1.) These observers regarded the digestive process as ended 
 when the food in the stomach had been reduced to a uniform 
 pulp, and altogether neglected the changes impressed upon 
 the food beyond the stomach. (2.) They used mixed, 
 variously prepared, often half vegetable and half animal food, 
 a method which is totally unfit for determining the digesti- 
 bility of individual articles of diet. (3.) No mention is made, 
 at least in Beaumont's experiments, of the quantity of food 
 that was taken, or of how minutely it was divided. Without 
 
DIGESTION. 455 
 
 entering into details of the discrepant observations made on 
 this subject by Schultz (who at a certain time, after feeding 
 dogs and cats with different kinds of food, killed them and 
 examined the contents of their stomachs), and by several other 
 physiologists, it is sufficient to quote the opinion of Blondlot, 
 who first introduced into physiology the operation of artificial 
 gastric fistula, and who obtained such very indefinite and in- 
 conclusive results, that he was led to express the view that 
 the digestibility of different articles of diet depended solely 
 on the state of the stomach at the time of the experiment, 
 and that it is pure waste of time to labour at the determina- 
 tion of the digestibility of individual articles of food.* Busch 
 found in his case of intestinal fistula that flesh, eggs, and 
 vegetables, began to appear at the fistulous opening in from 
 fifteen to thirty minutes after they were swallowed, but that 
 if a copious meal had been taken, traces of these substances 
 continued to appear for three or four hours. He gives the 
 following results : 
 
 Boiled eggs appeared in 3 expmts. after 26, 20, and 35 min. 
 Cabbage in 2 expmts. after 19 and 15 min. 
 
 Flesh in 2 expmts. after 30 and 22 min. 
 
 Parsneps after 12 minutes. 
 
 Potatoes after 15 minutes. 
 
 The following table, extracted from Busch's memoir, is 
 deserving of attentive study, as showing how much of each of 
 the articles of food mentioned in the first column was ab- 
 sorbed before reaching the fistula in the jejunum. 
 
 * The reader who may wish for further information on this subject is referred 
 pp. 312321 of the third volume of Lehmann's "Physiological Chemistry," 
 where he will find an account of the principal experiments made by himself and 
 other observers on the digestibility of soluble and coagulated albumen, of 
 coagulated blood-fibrin, of muscle and of pure syntonin, of casein, of the 
 fats, and of starch. 
 
 G G 4 
 
456 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Ratio of weight of 
 food to weight of 
 matters subse- 
 quently discharged 
 through the fistula. 
 
 Ratio of solid consti- 
 tuents of food to 
 solid constituents of 
 the matters dis- 
 charged through 
 the fistula. 
 
 Ratio of solid constituents 
 ofundissolved portion 
 of discharged matters 
 to the solid constituents 
 of the dissolved matters. 
 
 Grelatin 1 
 
 3-675 
 
 . 1 : 0-94 
 
 
 Boiled eggs 1 
 
 2-73 
 
 . 1 : 0-76 . 
 
 1 
 
 2-3 
 
 Flesh . 1 
 
 1-73 
 
 . 1 : 0-35 . 
 
 1 
 
 2-27 
 
 Milk . 1 
 
 1-25 
 
 . 1 : 0.62 . 
 
 -| 
 
 4-3 
 
 Parsneps . 1 
 
 1-2 
 
 . 1 : 0-49 . 
 
 1 
 
 0-94 
 
 Cabbage 1 
 
 0-91 
 
 . 1 : 0-58 . 
 
 1 
 
 0-66 
 
 Potato soup 1 
 
 0-7 
 
 . 1 : 0-53 . 
 
 1 
 
 1-5 
 
 From the experiments on which these numerical results 
 are based, Busch concludes that flesh is more digestible than 
 eggs, that parsneps are more digestible than potatoes or 
 cabbage, and potatoes more digestible than cabbage. 
 
457 
 
 CHAPTER XIX. 
 RESPIRATION. 
 
 (324.) THE process of respiration consists essentially in an Nature of 
 interchange of certain gases between the blood or nutrient thc P roccss - 
 fluid, and the external air, an evolution of carbonic acid and 
 an absorption of oxygen, which takes place, except in the 
 lowest animals, in definite organs, known as lungs, gills or 
 branchiae, and tracheae. Very low in the animal scale, as in 
 intestinal worms, numerous zoophytes, infusoria, &c., we have 
 no definite respiratory organs, the necessary interchange of 
 gases taking place through the external surface of the body 
 generally. 
 
 Passing over the description of the different modes of 
 carrying on experiments on respiration (for an account of 
 which we may refer to Lehmann's Physiological Chemistry, 
 vol. iii. pp. 330 332, or to any of our larger works on 
 Physiology), we proceed at once to the consideration of the 
 general results which have been yielded by the most im- 
 portant investigations regarding the interchange of gases in 
 the lungs. 
 
 The blood in the lungs gives off carbonic acid and aqueous 
 vapour to the inspired air, and takes up oxygen from the 
 latter; a very small quantity of nitrogen also commonly 
 passes from the blood into the respired air, although under 
 certain conditions the opposite sometimes occurs. 
 
 (325.) The first point in the chemistry of the respiration Ratio of 
 is to determine the ratio between the inspired oxygen and the oxygen to 
 exhaled carbonic acid. It is well known, that the volume of 
 carbonic acid is equal to the volume of the oxygen which is 
 
458 PHYSIOLOGICAL CHEMISTRY. 
 
 contained in it. If, therefore, a volume of carbonic acid were 
 found in the expired air which was equal to that of the oxy- 
 gen which had disappeared from the inspired air, we might 
 be led to infer that the oxygen which is absorbed in the pul- 
 monary vesicles, is exactly sufficient to form the carbonic 
 acid which they exhaled. This however is not usually the 
 case, for under ordinary relations, the volume of oxygen 
 which is absorbed is much larger than the volume of carbonic 
 acid which is exhaled, the oxygen serving not merely for the 
 oxidation of the carbon, but also for that of the hydrogen of 
 the animal constituents. If, for instance, animals be confined 
 in a closed vessel, we find on analysing the air which has 
 been modified by their respiration that more free oxygen has 
 disappeared than could have been employed in the formation 
 of the carbonic acid that has been simultaneously evolved. 
 On an average, for every volume of absorbed oxygen, there is 
 only about 0*8516 of a volume of carbonic acid in the expired 
 air ; so that about one-seventh of the inspired oxygen has to 
 be otherwise accounted for. 
 
 Volume of (326.) The volume of the expired is always greater than 
 that of the inspired air, partly because its temperature is 
 higher (from 97-2 to 99'5, according to Valentin), and partly 
 because it is usually much more saturated with aqueous vapour 
 than the inspired air. If however we examine both kinds of 
 air when freed from water and reduced to the same tempera- 
 ture, we find a diminution of the volume of expired air 
 corresponding to the volume of oxygen which has been ab- 
 sorbed, and has not been converted into carbonic acid. The 
 small quantities of nitrogen which are absorbed or exhaled 
 are (as we shall immediately show), too trifling to modify the 
 result, and may be neglected. 
 
 Amount of The quantity of water, in the form of aqueous vapour, that 
 
 aqueous i g exhaled by an adult man in 24 hours, has been variously 
 
 vapour. estimated by different observers. Valentin calculates it at 
 
 506 grammes, or about 14 ounces, and Vierordt at 360 
 
 grammes, or about 11 ounces. 
 
RESPIRATION. 459 
 
 The quantity of nitrogen in the air does not remain pre- Variations 
 cisely the same during respiration, but the difference is so 
 slight that it was for a long time a disputed point, whether 
 an excess of nitrogen was absorbed or exhaled during respira- 
 tion. Recent investigations sh'ow that there is an excretion 
 of nitrogen, although only in extremely small quantity ; the 
 relative weights of the excess of exhaled nitrogen over the 
 quantity in the inhaled air, and of the expired carbonic acid 
 being nearly as 1 : 100. A portion of this nitrogen occurs in 
 the expired air under the form of ammonia. When the same 
 air has been so repeatedly breathed by animals enclosed in a 
 bell-jar or other vessel, that asphyxia is imminent, the ratio 
 of the nitrogen to the carbonic acid is found to be much 
 increased.* 
 
 In addition to slight traces of ammonia, the expired Volatile 
 air frequently contains volatile substances that have been i n expired 
 taken with the food, such as alcohol, phosphorus, camphor, air - 
 ethereal oils, &c. ; and even when no such substances can be 
 detected in the food, the fact that the sulphuric acid, which 
 is used for drying the expired air, always becomes reddened, 
 indicates that traces of some organic carbo-hydrogen must be 
 present. The experiments of Regnault and Reiset seem to 
 establish the fact that appreciable quantities, both of hy- 
 drogen and protocarburetted hydrogen, are exhaled from the 
 lungs when in a perfectly normal condition. 
 
 * Although the researches of Regnault and Reiset establish the result given 
 in the text for mammals and birds, it is not universally true. The same ob- 
 servers found that there was little or no excess of nitrogen in the air expired 
 by batrachians (frogs and tritons), while in fishes there is an actual absorption 
 of nitrogen to a very considerable extent. Various conditions have been found 
 to modify the amount of the exhaled nitrogen. Regnault and Reiset ascertained 
 that a fowl which in summer exhaled 12 parts of nitrogen to 1000 of oxygen 
 which it consumed, in winter exhaled only 2 parts of nitrogen to the same 
 quantity of absorbed oxygen ; and that during hybernation nitrogen was ab- 
 sorbed. The same observers found that during an entire deprivation of food, 
 nitrogen was often absorbed by the lungs, and that the same was the case with 
 animals whose health had been affected by improper food. 
 
460 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Percent- 
 age of car- 
 bonic acid 
 in exaled 1 ' 
 air. 
 
 Influence 
 of rapidity 
 of respira- 
 tion on 
 amount of 
 carbonic 
 acid. 
 
 (327.) The air expired by a healthy man in a state of re- 
 pose, contains on an average 4*334 per cent, by volume of 
 carbonic acid. According to Scharling a muscular adult man 
 exhales in twenty-four hours 867 grammes, or 2 7 '8 ounces of 
 carbonic acid (or about 27*058 cubic inches, reckoning the 
 barometer at 29*9 inches, and the temperature at 32) ; while 
 according to Boussingault about 8 grammes (or rather more 
 than half an ounce) of nitrogen, and according to Valentin 
 about 500 grammes (or about 16 ounces) of watery vapour are 
 also exhaled in the same period. As about 746 grammes, 
 or about 23*3 ounces of oxygen are inhaled during that 
 period, it has been shown by calculation that about 116 
 grammes, or rather more than three ounces, of that gas are 
 retained in the organism.* 
 
 (328.) It has been proved by Vierordt that the amount of 
 carbonic acid in the expired air is very dependent on the 
 frequency of the respiratory movements. Having ascertained, 
 by numerous careful observations on himself, that the carbonic 
 acid in 100 volumes of his expired air, when breathing normally 
 nearly twelve times in a minute, amounted to 4*334 volumes, 
 he tried the experiment of doubling the rapidity without 
 diminishing the normal depth of the inspiration; and he 
 found that the relative quantity of carbonic acid was about 
 907^ less than in normal undisturbed respiration ; when the 
 number of inspirations was increased to three times their 
 former amount, this diminution amounted to 1*125^; when 
 the number was increased four-fold, the diminution amounted 
 to 1*292^-; and finally, when they were increased eight-fold, 
 the diminution amounted to 1*600^. When the number of 
 inspirations was diminished by one half (when six instead of 
 twelve inspirations were taken in the minute), there was an 
 excess of carbonic acid to the amount of 1*316. 
 
 * These numbers are given by Lehmann in his Lehrbuch, Handbuch, and 
 Zoochemie, but I do not clearly understand how he has arrived at this result. 
 
INSPIRATION. 461 
 
 These results stand out more clearly in the following 
 tabular arrangement : 
 
 Acts of respiration Carbonic acid in 100 
 
 in one minute. volumes of expired air. 
 
 6 . . 5-528 
 
 12 4-262 
 
 24 3-355 
 
 48 . .. 2-984 
 
 96 ..... . 2-662 
 
 From these and other observations of a similar character, 
 Vierordt has been able to show (after introducing certaiij 
 corrections) that the number of respirations is a function of 
 the number expressing the corresponding percentage -of 
 carbonic acid. Thus, for every expiration without reference 
 to its duration, there is a constant amount of carbonic acid 
 (of 2-5-g), to which we must add a second and variable amount 
 which is proportional to the duration of the expiration. The 
 following table will elucidate our meaning : - 
 
 Respirations. Total per- Constant Varying 
 
 centage of CO 2 . percentage. percentage. 
 
 6 . . 5-7 . . 2-5 . . 3-2 
 12 . . 4-1 . . 2-5 . . 1-6 
 24 . . 3-3 . . 2-5 . 0-8 
 
 48 . . 2-9 . . 2-5 . .' 0-4 
 96 . . 2-7 ' 2-5 0-2 
 Now, if the respirations are 6 in the minute, each respi- 
 ratory act has a duration of 10" ; if they are 12 in the minute, 
 each has a duration of of 10", and so on ; hence, taking 10", 
 2-5, and 3-2 as constants, we have this relation connecting 
 the duration of the respiration with the amount of carbonic 
 acid : 
 
 A respiration lasting 
 
 10" yields air containing 2-54-3-2 of carbonic acid. 
 oflO" 2-5 + 1 of 3-2 
 
 ioflO" 2-5 +i of 3-2 
 
 loflO" 2-5 -H of 3-2 
 
462 PHYSIOLOGICAL CHEMISTRY. 
 
 and so on, till we come to the limit beyond which we cannot 
 count the respiratory acts. 
 
 According to Vierordt's experiments about 30*5 cubic 
 inches of air are expelled by one expiration while the 
 breathing is undisturbed. If we assume that during hurried 
 respiration an equally large quantity of air is expelled by 
 expiration (which however is hardly likely to be the case), we 
 may easily calculate the absolute amount of carbonic acid 
 exhaled in a minute. The results are as follows : 
 
 Number of Carbonic acid Cubic inches of Cubic inches Cubic inches 
 
 respirations in in 100 volumes air expired in of carbonic acid of carbonic acid 
 
 one minute, of expired air. one minute. expired in one exhaled in one 
 
 minute. expiration. 
 
 6 5-7 185 10-5 1-7 
 
 12 4-1 375 13-4 1-3 
 
 24 3-3 750 -. 24-4 1-0 
 
 48 2-9 1500 42-5 0-88 
 
 96 2-7 3000 80-0 0-82 
 
 Although several other causes exert a decided influence on 
 the quantity of carbonic acid in the exhaled air, there can be 
 no doubt that this law holds good for otherwise similar 
 conditions, and we must agree with him in holding it proved 
 that " the rhythm of the respiration acts as the most powerful 
 regulator of the excretion of carbonic acid." 
 
 The depth or intensity of the individual respirations exerts 
 a similar influence on the excretion of carbonic acid. The 
 following decisive results have been obtained by Vierordt. 
 
 Per cent, of car- 
 bonic acid. 
 
 If the air in a normal respiration contains 4-60 
 
 The air in a respiration twice as deep contains* 4*00 
 
 , : three times 3*70 
 
 four times 3-38 
 
 eight times 2*78 
 
 half " 5-38 
 
 * The slight apparent discrepancy between the results in this and the pre- 
 ceding table, is due to certain corrections haying been introduced by Vierordt 
 in the present one. 
 
RESPIRATION. 463 
 
 (329.) The quantity of carbonic acid in the air in the Excess of 
 upper and lower portions of the lungs differs very considerably. ac id in last 
 According to Allen and Pepys, whose observations were made 
 more than half a century ago, the first portion of the air 
 yielded by a deep expiration contained from 3-5 to 5-g- of 
 carbonic acid while the last portion yielded as much as 9-5%. 
 To investigate this point, Vierordt made seven experiments, 
 in which he divided each expiration as nearly as pos- 
 sible -into two equal parts, and found that the carbonic acid 
 contained in the air breathed during the first half of the 
 expiration amounted to 3*72--, while that contained in the 
 second half amounted to 5-44-g-. This result shows that Allen 
 and Pepys had greatly overestimated the difference in the 
 percentage of carbonic acid, and accords closely with the 
 result of Jurine, who, in dividing expirations into four equal 
 portions, found the values of carbonic acid in the first and 
 last to be in the ratio of 1*01 '. 1*51. He likewise obtained a 
 similar result by comparing the amount of carbonic acid in a 
 normal expiration with that in the air obtained by an 
 intensely forced expiration. As a mean of eight experiments 
 he found that while the carbonic acid of a normal expiration 
 of 34 "cubic inches amounted to 4-63-g-, a most complete and full 
 expiration of 111 cubic inches contained 5-18-g-. The carbonic 
 acid in the two cases amounted to 1*64 and 5-82 cubic inches ; 
 hence in the deeper portion, amounting to 77 cubic inches, 
 there are 4-12 cubic inches, or 5-43^ of carbonic acid, and there- 
 fore 0'80-g- more than are contained in the air given off in a 
 normal expiration. Vierordt calculates that the air in the 
 pulmonary vesicles contains as much as 5-83-g- of carbonic 
 acid and therefore 1-2-g- more than is contained in a normal 
 expiration. 
 
 (330.) It has been shown by the independent observations Influence 
 of Vierordt and* Horn that if the respiration be suspended suspension 
 for a given time (varying in these experiments from 10 to 100 ^Jj espira " 
 seconds) the expired air contains a considerably less total 
 
464 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 quantity of carbonip acid than it ought to do, but a consider- 
 able relative augmentation of that gas. This relative aug- 
 mentation is clearly shown in the following results obtained 
 by Becher.* 
 
 Seconds. 
 Respiration stopped for 10 
 
 20 
 40 
 60 
 80 
 100 
 
 3'636f of carbonic acid. 
 
 5'552 
 
 6-2654. 
 
 7-282-g- 
 
 Influence 
 of artificial 
 atmo- 
 spheres. 
 
 (331.) We proceed to the consideration of the changes in- 
 duced by the inhalation of artificial atmospheres, or different 
 kinds of gas. The experiments of Regnault and Eeiset on dogs 
 and rabbits, show that the respiration of air which is richer 
 in oxygen than the atmosphere, does not produce any marked 
 Q f xc results ; the animals did not exhibit any distress from the 
 of oxygen, inhalation of air containing two or three times more oxygen 
 than our atmosphere, and the products of respiration were 
 in no way afFected.-f- W. Miiller has attempted to determine 
 the extent to which the oxygen may be diminished in an 
 atmosphere without affecting the action of respiration. He 
 finds that an atmosphere containing 14-8-J of oxygen (or 
 about two-thirds of the quantity contained in common air), 
 exerts no apparent deleterious action on the respiratory pro- 
 
 * Zeitsch. f. rat. Med. New Ser. vol. vi. pp. 249287. 
 
 f Lavoisier and Seguin, and Allen and Pepys (from observations on man), 
 and Marehand (from observations on the frog), came to the conclusion that 
 although the excretion of carbonic acid was not (to any appreciable extent) 
 increased by the respiration of pure oxygen, far more (Marehand says twice 
 as much) oxygen is retained in the blood than in ordinary respiration. Bernard 
 has observed that animals in an atmosphere of pure oxygen exhibit great ex- 
 citement and activity. Their lips are of a bright red tint, and their blood 
 presents an arterial character, the circulation is rapid, the secretions increased, 
 and the muscles contract with energy. The urine of rabbits during the process 
 of digestion is alkaline, but if they are placed in an atmosphere of oxygen, the 
 urinary secretion becomes acid in a quarter of an hour, and is found to contain 
 an excess of urea. 
 
RESPIRATION. 465 
 
 cess ; but that if the oxygen is reduced to 7 (or one-third of 
 the ordinary quantity), the animals are observed to take 
 deeper and more forcible inspirations ; while if it is reduced 
 to 3-g- they rapidly die with symptoms of suffocation. 
 
 Pure carbonic acid cannot be inhaled, because the glottis Of excess 
 spasmodically obstructs its passage. Marchand found in ex-* 
 
 periments on frogs, that when they were made to inhale an 
 atmosphere rich in carbonic acid (but not so rich as to be irre- 
 spirable) less oxygen was absorbed; and less carbonic acid, 
 but more nitrogen was exhaled than in ordinary respiration. 
 Bernard found that animals can live in air till (by their repeated 
 respirations) its carbonic acid has increased to 12 or even 
 18-g-; if however, they are at once transferred from the pure 
 air to an atmosphere containing such a per-centage of carbonic 
 acid, they are immediately killed, even though an abundance 
 of oxygen be simultaneously present. W. Miiller found that 
 animals placed in closed vessels of sufficient size, are not 
 affected by the gradual augmentation of the carbonic acid, 
 until they have absorbed about a third part of their bodily 
 volume of carbonic acid. Symptoms of narcosis, such as cold- 
 ness of the extremities, slowness of the respiratory acts, and 
 rapidity (combined with weakness) of the heart's action, then 
 set in ; and after the animal has absorbed 56 or 58-g- of its 
 own volume of carbonic acid, death ensues without any con- 
 vulsive actions, although plenty of oxygen for the support of 
 life still remains. 
 
 It appears from Legallois' experiments on guinea pigs, that Of excess 
 in an air which is richer in nitrogen than the atmosphere, 
 nitrogen is absorbed, and less than the normal quantity of car- 
 bonic acid exhaled ; there appears also to be an increased 
 absorption of oxygen. 
 
 The inhalation of pure nitrogen is speedily followed by 
 symptoms of suffocation, but during the short time the ex- 
 periment can be continued, rather an excess of carbonic acid 
 is exhaled. 
 
 H it 
 
466 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 Respira- 
 tion of 
 nitrous 
 oxide. 
 
 Of hydro- 
 gen. 
 
 Of car- 
 bonic 
 oxide. 
 
 The respiration of nitrous oxide induces pleasurable sensa- 
 tions, considerable excitement, and a state resembling intoxi- 
 cation, which after the lapse of five or ten minutes passes into 
 asphyxia. According to Sir Humphry Davy, carbonic acid 
 is given off in no larger quantity than usual, but Zimmermann 
 found that a rabbit, which in atmospheric air exhaled 0*8 of 
 a gramme of carbonic acid in one hour, exhaled 1 *3 grammes 
 in nitrous oxide gas. 
 
 Eespiration may go on for a considerable time in an 
 atmosphere containing hydrogen gas, if a sufficient quantity of 
 oxygen be present. Eegnault and Keiset placed rabbits and 
 dogs in atmospheres in which almost all the nitrogen had 
 been replaced by hydrogen (from 55 to 7 7-- of hydrogen, from 
 M to 14-4-g- of nitrogen, and frem 21-8 to 28-8-g- of oxygen), 
 and the rabbits inhaled this mixture for 20, and the dogs 
 for 10 hours, without any apparent injury, except that the 
 respiration was increased in force. At the close of the ex- 
 periment, nearly the original quantity of hydrogen was found, 
 but rather more than the usual quantity of oxygen had been 
 absorbed. It is clear from these experiments, that the only 
 reason why respiration cannot be carried on for any length of 
 time in pure hydrogen gas is, that the organism is thus de- 
 prived of the oxygen necessary for life. Marchand found 
 that frogs died in from half an hour to an hour after being 
 placed in pure hydrogen gas, but that during this time they 
 developed more than three times as much carbonic acid 
 as they would have done in the same period in atmospheric 
 air. 
 
 Carbonic oxide, when mixed even in very minute quantity 
 (0*54 according to Leblanc*, or 0*6 according to Bernard) 
 gives rise to faintness, feelings of suffocation, stupefaction, and 
 death. Leblanc has shown that it is to this constituent that 
 choke-damp owes its fatal effects. The mode in which it 
 
 * Compt. Rend. vol. xxx. p. 483. 
 
RESPIRATION. 467 
 
 proves fatal is illustrated by the observations of Meyer, who 
 finds that it combines very readily with the blood and displaces 
 the oxygen. 
 
 (332.) We now proceed to notice the effects produced by Atmo 
 various atmospheric conditions upon the respiration and its 
 products. 
 
 The temperature of the atmosphere first claims our atten- 
 tion. As Spallanzani, and several subsequent observers had 
 noticed that hybernating animals (marmots, bats, and hedge- 
 hogs) exhaled least carbonic acid at a low temperature, when 
 their vital activity was more or less depressed, it was assumed 
 as a general proposition that a depression of the surrounding 
 temperature would constantly produce this effect in all classes 
 of animals. Letellier, however, shows in his experiments 
 upon several different kinds of birds and mammals that the 
 largest relative amount of carbonic acid is exhaled at a tem- 
 perature between 23 and 37, and the smallest between 82 
 and 109. The difference was more marked in birds than in 
 mammals. None of the animals could bear a higher temperature 
 than 109 or 110. Marchand has obtained many similar 
 results with frogs, except that they fell into a torpid state at 
 between 35 and 37, when they excreted a remarkably small 
 amount of carbonic acid. The action of the increased tem- 
 perature is probably of an indirect nature, the result being 
 apparently due to a diminution both of the number and of the 
 depth of the respiratory acts. Vierordt has ascertained that 
 at high temperatures less than the usual quantity of aqueous 
 vapour is given off. 
 
 Vierordt has calculated a table of the respiratory functions 
 from 37 to 75. We have divided the total result into two 
 parts, one representing the means of the values obtained at 
 the lower degrees of temperature from 37 P to 56, and the 
 other those between 57 and 75. 
 
468 PHYSIOLOGICAL CHEMISTRY. 
 
 Average Temperature. Difference. 
 
 47-2 67 
 
 Pulsations in one minute 72-93 7T29 T64 
 
 Respirations 12-16 11'57 0'59 
 
 Volume of one expiration 33*5 cubic in. 31-8 cubic in. 1*7 cubic in. 
 
 Air expired in one minute 407'0 367'2 39'8 
 
 Carbonic acid 18'3 157 2-6 
 
 Carbonic acid in 100 parts 
 
 of expired air . . 4-48 4-28 0'2 
 
 Dr. E. Smith *, in his memoir " On the Chemical and other 
 Phenomena of Respiration," has fully investigated the effects 
 of the different seasons on the respiratory process, and to 
 some extent overthrown the above conclusions. " There 
 are," he observes, "great variations from season to season, 
 so that as the hot season advances, all the respiratory pheno- 
 mena are lessened. The diminution in myself at the middle 
 of August was 30 per cent, of air, 32 per cent, in rate of re- 
 spiration, and 17 per cent, of carbonic acid. In Mr. Moul 
 (one of the gentlemen experimented on) to the middle of 
 June, the diminution was 27 per cent, of air and also of 
 carbonic acid, and 28 per cent, to the rate of respiration. 
 
 66 Spring is the season of the greatest, and the autumn of 
 the least activity of the respiratory and other functions. 5 ' 
 
 "Temperature and atmospheric pressure only partially 
 explain the effect of season, for with the same temperature, at 
 different seasons, there is a great diversity in the carbonic 
 acid expired, and particularly with a medium temperature, 
 as for example 59, with which the quantity of carbonic acid 
 was 9'13 grains (in the minute) in the spring, and 6 '76 grains 
 in the summer and autumn. The relation of temperature and 
 pressure to the carbonic acid is an inverse one, the former 
 acting in an increasing ratio in cases of sudden increase." 
 
 * I regret very much that I have not been able to make more use of Dr. 
 Smith's valuable memoirs, which I only received as these pages were going 
 through the press. They are contained in the Philosophical Transactions for 
 1859, and are deserving of the highest praise for the great amount of personal 
 experiment and research which they record. 
 
RESPIRATION. 469 
 
 cs The period of permanent decline in the carbonic acid is 
 May and June, and at the period of minimum quantity 
 there is the greatest uniformity." 
 
 The moisture of the atmosphere exerts an influence on the Moisture, 
 respiratory functions, and especially on the excretion of 
 carbonic acid. Lehmann found from experiments * on wood- 
 pigeons, green-finches and rabbits, that the weight of carbonic 
 acid excreted in moist air greatly exceeds that eliminated in 
 a dry atmosphere. For example, 1000 grammes weight of 
 wood-pigeons excreted 4'69 grammes of carbonic acid in one 
 hour in dry air at a temperature of 98-6, and 7 '76 grammes 
 in moist air at the same temperature. (At a lower tempera- 
 ture, e. g. 74, the difference is less marked, the number of 
 grammes being 6-06 and 6'77) ; similarly 1000 grammes 
 weight of green-finches yielded in dry air 3*22, and in moist 
 air 6 P 8 6 grammes of carbonic acid at the temperature of 
 99-5; and 1000 grammes weight of rabbits yielded 0-451 of 
 a gramme of carbonic acid in dry air, and 0'677 of a gramme 
 in moist air at a temperature of 99-5. 
 
 The influence of the pressure of the air has been investi- Atmo- 
 gated by Vierordt on man, and by Legallois and by Lehmann pressure. 
 on mammals and birds. A rise of the barometer (e. g. an 
 increased atmospheric pressure) renders the pulse and re- 
 spiration more rapid, and increases the amount of expired air ; 
 as however the per-centage of the carbonic acid in the 
 exhaled air is diminished, the absolute amount is not much 
 affected. Sudden changes of pressure in either direction give 
 rise to increased frequency of the respirations, and thus 
 augment the quantity of carbonic acid ; but if the change be 
 gradually effected the pressure may be increased or diminished 
 to a great extent without materially altering the amount of 
 
 * These experiments seem to have a direct bearing on the treatment of 
 disease. When we wish to check the too rapid waste of tissue (of which the 
 excreted carbonic acid is a measure), we should clearly recommend a dry in 
 preference to a moist atmosphere. 
 
 H H 3 
 
470 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 carbonic acid that is exhaled in a given time. In Lehmann's 
 experiments the animals were quite as lively and as much 
 disposed to eat, with the barometer either at 34 or at 22 
 inches as at the mean pressure. 
 
 Prout was led to believe from his experiments that the 
 different periods of the day exerted a direct influence upon 
 the exhalation of carbonic acid. Although his experiments 
 were doubtless made with his well-known accuracy, it is 
 probable (as Scharling, Vierordt and Lehmann suggest) that 
 the differences observable in the amount of carbonic acid are 
 far more dependent upon internal conditions of the organism, 
 such as digestion, waking and sleeping, &c. than on the 
 special periods of the day. Marcfcand, who formerly held the 
 opposite opinion, now believes that the influence of day and 
 night are very inconsiderable, and that the slight diminution 
 which the carbonic acid presents during the night can only 
 be referred to the more quiet condition of the animal at that 
 period. Moleschott found that light (independently of the 
 period of the day) exerted, in the case of frogs, a decided 
 influence in promoting the excretion of carbonic acid ; and 
 this fact may have a bearing on Prout's experiments. 
 
 From experiments made by Barral and Vierordt it appears 
 that in the winter there is a greater exhalation of carbonic 
 acid (by about one-fifth) than in the summer. Dr. Smith 
 does not think that these observations were made with such 
 regularity and with such identity of external conditions as to 
 educe the true effect of season. His own observations how- 
 ever (see p. 468) on the whole confirm the views of Barral and 
 Vierordt. The following are the monthly averages of the 
 carbonic acid per minute obtained by Dr. Smith from obser- 
 vations upon himself: we add the mean temperature, inspired 
 air, pulse, and respirations per minute. 
 
INSPIRATION. 
 
 471 
 
 
 Temperature. 
 
 Carbonic Acid. 
 
 Air. 
 
 Pulse. 
 
 Respirations. 
 
 
 
 Grains. 
 
 Cubic In. 
 
 
 
 April . 
 
 54'5 
 
 8-58 
 
 498 
 
 72'8 
 
 14-3 
 
 May . 
 
 58-1 
 
 8-89 
 
 457 
 
 68-3 
 
 12-4 
 
 June . 
 
 71-7 
 
 8-19 
 
 426 
 
 7M 
 
 11-64 
 
 July . 
 
 65-1 
 
 7-62 
 
 393 
 
 69-8 
 
 11-0 
 
 August 
 
 66'6 
 
 7-15 
 
 392 
 
 73'3 
 
 10-9 
 
 September 
 
 61-2 
 
 7-13 
 
 402 
 
 66-6 
 
 10-94 
 
 October 
 
 52-8 
 
 7'67 
 
 395 
 
 69-8 
 
 10-93 
 
 November 
 
 43-8 
 
 7-86 
 
 414 
 
 69-1 
 
 10-87 
 
 December 
 
 45-2 
 
 8-27 
 
 429 
 
 67-0 
 
 11-15 
 
 January 
 
 43-1 
 
 8-35 
 
 447 
 
 68-8 
 
 11-73 
 
 February 
 
 46-3 
 
 8-20 
 
 
 69-2 
 
 11-35 
 
 March 
 
 48-9 
 
 8-25 , 
 
 
 
 70-9 
 
 11-38 
 
 nence. 
 
 (333.) All internal conditions of the system, and especially Internal 
 those which affect nutrition and consequently the state of O f the or- 
 the blood, exert a marked influence on the respiration, as S anism - 
 starvation, digestion, &c. 
 
 Numerous observers, amongst whom we may especially Absti- 
 mention Letellier, Boussingault, Marchand, Regnault and 
 Keiset, and Bidder and Schmidt, have carefully studied 
 the effect of perfect abstinence (inanition) on the respiratory 
 process. A tolerably full summary of these experiments may 
 .be found in Lehmann's " Physiological Chemistry," vol. iii. pp. 
 351-54; the main results being as follows. In cases of 
 perfect abstinence from food the absorption of oxygen 
 diminishes with tolerable constancy till death ensues, the 
 diminution being rather more rapid at the beginning and at 
 the close of the experiment than at the middle. In the 
 early part of the experiment about 80% of the absorbed 
 oxygen is expended in the formation of carbonic acid, while 
 at the close of the experiment only 73-g- is thus used. The 
 quantity of excreted carbonic acid diminishes with tolerable 
 uniformity and rapidity during the first third of the ex- 
 periment, more slowly during the second third, and again 
 more rapidly during the last third. The quantity of aqueous 
 vapour which is daily exhaled decreases during inanition 
 slowly and with tolerable regularity, but the decrease is 
 
 H H 4 
 
472 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 somewhat more rapid at the beginning and end of the 
 experiment. When water was allowed the daily amount of 
 carbonic acid was far less considerable than when both solids 
 and fluids were withheld. In birds and sometimes in 
 mammals an absorption of nitrogen was observed. 
 
 Vierordt found that the omission of even a single meal con- 
 siderably modifies the respiratory products, the absorption 
 of oxygen and the excretion of carbonic acid being perceptibly 
 diminished. His statement that there is a marked augmenta- 
 tion both of the absorbed oxygen and of the exhaled carbonic 
 acid during the two hours that succeed the ingestion of a 
 meal, has been confirmed by the observations of Seharling, 
 Becher, and Smith; the latter found that the maximum 
 quantity of carbonic acid was observed in from one to two 
 hours after a meal, the increase beginning immediately after 
 its ingestion. 
 
 Dr. Smith found that in a prolonged fast of twenty- seven 
 hours the diminution per cent, from the quantities in a day 
 with food, was 25 of carbonic acid, 30 of air, 37 of vapour,- 
 7 of rate of respiration, and 6 of rate of pulsation. 
 
 The composition of the expired air is very uniform during 
 fasting. Dr. Smith found that at the end of the twenty- 
 seven hours the quantity of exhaled carbonic acid was the 
 same as at four and a half hours after the beginning of the 
 experiment. 
 
 (334.) It has been proved by various experimentalists 
 (Dulong, Despretz, Lassaigne and Yvart, and Regnault and 
 Reiset) that the products of respiration are essentially modi- 
 fied by the chemical character of the food. The most recent 
 of these observers, Regnault and Reiset, found that a much 
 larger quantity of oxygen was employed in the formation of 
 carbonic acid when dogs had been fed on amylaceous sub- 
 stances, than when the food had been of a purely animal 
 nature ; in the latter case only 74*5 of every 100 parts of the 
 absorbed oxygen were found again in the carbonic acid ; while 
 
RESPIRATION. 473 
 
 in the former 91-3 parts of oxygen went to form carbonic acid. 
 Nitrogen was eliminated during a vegetable diet, but in far 
 less quantity than during an animal diet. In a dog which 
 had been fed on mutton suet, only 69-4 of the absorbed 
 oxygen was employed in the formation of carbonic acid, and 
 nitrogen was neither exhaled nor absorbed. 
 
 We can account chemically for these differences in relation 
 to the absorbed oxygen and the exhaled carbonic acid, if we 
 assume (which at present we must do) that all the carbon 
 and hydrogen of the fats and carbo-hydrates, derived from 
 the food, are entirely oxidised in the body into carbonic acid 
 and water. Now these substances require very different 
 quantities of oxygen for their perfect oxidation. The mean 
 composition of the fats is about 78-13 C, 11-64 H, and 
 10-13 0. The oxidation of the carbon and of the hydrogen 
 in 100 parts of fat (into carbonic acid and water) would re- 
 quire 208-35 + 93-92, or 302-27 grammes of oxygen; but as 
 the fat already contains 10*13^ of oxygen, the quantity 
 actually required is 292*14 grammes. When we compare the 
 composition of sugar or of starch with that of fat, we see that 
 the carbo-hydrates require far less oxygen for their complete 
 oxidation, because, in the first place, they contain enough 
 oxygen to oxidise their hydrogen ; and secondly, because for 
 equal weights there is far less carbon to be oxidised in the 
 carbo-hydrates than in fat. Certain organic acids, such as 
 tartaric and citric acids, which occur in many kinds of *vege- 
 table food, contain so large an amount of oxygen, that it not 
 only oxidises the hydrogen but a part of the carbon. When 
 animals are fed on nitrogenous food, we know that a portion 
 of the carbon, hydrogen, and oxygen is carried off with the 
 nitrogen in the form of urea, and other less abundant nitro- 
 genous constituents which we may neglect in the present 
 consideration. Hence we can only consider that a portion of 
 the albuminates, and similar substances, is capable of support- 
 ing respiration, and we determine that portion by abstracting 
 
474 PHYSIOLOGICAL CHEMISTRY. 
 
 from the composition of the albuminates, and other nitro- 
 genous nutrient substances, an amount of urea equivalent to 
 the quantity of nitrogen which they contain.* 
 
 It we take oxygen as our unit, and calculate how much of 
 each of these various articles of food is required to form car- 
 bonic acid and water by combining with the unit of oxygen, 
 we obtain what have been termed by Liebig respiratory equi- 
 Rcspiratory valents, which stand in an inverse ratio to the value which 
 Qts ' each individual nutrient substance possesses for undergoing 
 oxidation in the animal body, or (which is the same thing) for 
 the development of animal heat. If, for instance, we assume 
 that an organism in the full performance of its vital powers 
 must consume about 100 grammes (or any other measure) of 
 oxygen in a definite time, the following quantities of different 
 articles of food would be required for the formation of car- 
 bonic acid and water, namely, 34 '23 grammes of fat, 84-37 
 grammes of starch, 93'75 grammes of sugar, 120'80 grammes 
 of malic acid, and 65*23 grammes of dry albuminates. The 
 youngest student of physiology knows that no individual sub- 
 stance taken from this series can of itself support life ; and in 
 the next chapter we shall endeavour to determine the pro- 
 portion in which they ought to be mixed, so as to form the 
 most profitable and nourishing food. The numbers must 
 merely be regarded as proportional estimates of the relative 
 values of the different substances in reference to respiration. 
 The following table gives a succinct view of these relations, 
 
 * If we abstract the sulphur, phosphorus, and salts, from the albumiuates, 
 we may regard them as composed of 
 
 Carbon ...... 54-36 
 
 Hydrogen . . . . . . 7-27 
 
 Nitrogen . . . . . . 16'05 
 
 , Oxygen . . . . . 22-32 
 
 In urea for every 16'05 parts of nitrogen there arc 6'88 of carbon, 2 29 of 
 hydrogen, and 9' 18 of oxygen. If we deduct these quantities from the corre- 
 sponding quantities in the albuminates, there are left of the latter 47*18 parts of 
 carbon, 4-98 of hydrogen, and 13-14 of oxygen, which, we must presume, arc 
 oxidised and appear in the respiratory products. 
 
RESPIRATION. 
 
 475 
 
 the unit now being, however, 100 parts of the nutrient sub- 
 stance, not 100 parts of oxygen. 
 
 Substance. 
 
 Carbon. 
 
 Hydrogen. 
 
 gen required for 
 the formation of 
 Oxygen. CO 2 and HO, in 
 addition to the 
 
 amount already 
 
 1 00 parts of fat . 
 
 78'13 
 
 11-74 
 
 present. 
 10-13 292-14 
 
 starch 
 
 44-45 
 
 6-17 
 
 49-38 
 
 118-52 
 
 sugar (C 12 H 12 O 12 ) . 
 
 40-40 
 
 6-66 
 
 53-34 
 
 106-67 
 
 ,, malic acid (C 4 H 2 O 4 ) 
 
 41-38 
 
 3-45 
 
 55-17 
 
 82-78 
 
 albuminates 
 
 47-48 
 
 4-98 
 
 13 14 
 
 153-31 
 
 The recent researches of Dr. Smith have led to the follow- Dr. Smith's 
 ing results. 
 
 1. It follows from numerous experiments that food may be 
 divided into two classes, viz. : those which excite certain 
 respiratory changes (excito-respiratory) and those which do 
 not. 
 
 The excito-respiratory are nitrogenous foods, milk and its 
 components, sugars, ram, beer, stout, the cereals and potato. 
 
 The non- exciters are starch, fat, certain alcoholic com- 
 pounds, the volatile elements of wines and spirits, and coffee 
 leaves. 
 
 2. Of the hydro-carbons, fine starch exerts but an in- 
 significant influence over the increase of carbonic acid, and 
 the addition of fat to starchy food lessens, rather than 
 increases the influence of the latter ; fats (olive and cod liver 
 oil) taken alone diminish the respiratory changes; while 
 sugar in every form is a powerful respiratory excitant. 
 
 Dr. Smith is fully aware that some of the results quoted 
 here and in the preceding pages are not in accordance with 
 commonly received physiological opinions, but after carefully 
 reconsidering his labours, he finds no reason to distrust the 
 truthfulness of his observation. 
 
 (335.) The quantity as well as the quality of the food Influence 
 exerts a very considerable influence on the amount of the of food"' 1 
 interchange of gases in the lungs. The following experiment 
 made by C. Schmidt on a cat will sufficiently illustrate this 
 
476 PHYSIOLOGICAL CHEMISTRY. 
 
 fact. When the animal was taking 142-41 grammes of flesh 
 daily (a quantity which was quite sufficient to maintain its 
 full strength and ordinary weight), it absorbed 60-14 grammes 
 of oxygen, and exhaled 65-60 grammes of carbonic acid, 
 together with 30-88 grammes of water; whilst during the 
 the consumption of 247*32 grammes of flesh it absorbed 
 103-84 grammes of oxygen, and exhaled 113-52 grammes of 
 carbonic acid, and 47*86 grammes of water. 
 
 (336.) Vierordt and Bocker agree with Prout in find- 
 ing that the excretion of carbonic acid is both absolutely and 
 relatively diminished even after a moderate use of alcoholic 
 drinks. In reference to this statement Dr. Smith observes, 
 
 (1) that alcohol alone was not used in the whole of Front's 
 and Vierordt's experiments, but various substances containing 
 alcohol were used by the former and white wine by the latter ; 
 
 (2) that there is the utmost variation in the composition 
 and quality of fluids of this kind ; and (3) that there was 
 probably great variation in the habits of some of the ex- 
 perimenters. 
 
 His own observations on the effects of alcohol have led to 
 several singular and unaccountable results. The following 
 are his chief conclusions 
 
 1. The direct action of pure alcohol was much more to 
 increase than to lessen the respiratory changes, and some- 
 times the former effect was very distinct. 
 
 2. Brandy, whisky, and gin (particularly the latter) almost 
 always lessened the respiratory changes, whilst rum. as 
 commonly increased them. Rum and milk had a very 
 pronounced and persistent action. Ale and porter always 
 increased them, while sherry lessened the quantity of air 
 inspired, but slightly increased the carbonic acid evolved. 
 
 3. The volatile elements of alcohol, gin, rum, sherry, and 
 port, when inhaled, lessened the quantity of carbonic acid 
 exhaled, and usually lessened the quantity of air inhaled. 
 The effect of fine old port was very decided. The excito- 
 
RESPIRATION. 477 
 
 respiratory action of mm is probably not due to its volatile 
 elements. 
 
 4. In these experiments there was no parallelism between 
 the exhalation of vapour and of carbonic acid. 
 
 Prout, Vierordt, and Bocker, found that strong tea and 
 coffee, like spirituous liquor, occasioned both an absolute and 
 a relative diminution of the carbonic acid. Dr. Smith's 
 results do not support this view. He finds from his experi- 
 ments on this class of substances : 
 
 1. That tea, coffee, chicory, and cocoa, are respiratory 
 excitants, whilst coffee leaves depress the respiratory function. 
 
 2. Tea is the most powerful, then coffee and cocoa, and 
 lastly, chicory. 
 
 3. The addition of an acid or alkali lessens the effect of tea. 
 
 4. The addition of sugar and milk in the ordinary way 
 increases the effect. 
 
 5. Cold tea and tea infused and kept twenty-four hours, 
 has as much effect as when hot and recently made. 
 
 6. The influence of both tea and coffee is exerted almost 
 immediately, and the maximum is attained in from twenty- 
 five to sixty minutes. The duration varies from one to two 
 hours. 
 
 Strong tea and coffee, ethereal oils, &c., produce a similar 
 effect. 
 
 (337.) It has been shown by the experiments of Scharling Of sleep, 
 on men and by those of Lehmann on birds, that sleep causes 
 a very considerable diminution in the amount of the excreted 
 carbonic acid. A man, who after dinner exhaled 33-69 
 grammes of carbonic acid in an hour, exhaled only 22-77 
 grammes during an hour while sleeping ; in another case the 
 ratio was 40-74:31-39. 
 
 The respiratory products of animals in the hybernating Ofhyber- 
 state (especially marmots) have been carefully studied by 
 Regnault and Reiset. In their active state marmots, for every 
 1000 grammes of their bodily weight, absorb from 077 to 
 
478 PHYSIOLOGICAL CHEMISTRY. 
 
 1'2 grammes of oxygen in an hour, while in their hybernating 
 condition they consume only from 0*04 to 0*05 of a gramme. 
 In the hybernating animals only 56-7-g- of the absorbed oxygen 
 passes into carbonic acid, whilst in the active state the 
 quantity amounts to about 73-g-. These observers found that 
 the marmots when they awake from their hybernation exhale 
 an extremely large quantity of carbonic acid and consume an 
 excessive quantity of oxygen an observation which corre- 
 sponds with the fact, noticed both by Prout and Vierordt, 
 that man for half an hour or nearly an hour after waking 
 exhales an excess of carbonic acid. 
 
 Of exer- There is abundant evidence that bodily exercise increases 
 
 cise. 
 
 both the absolute and the relative amount of carbonic acid. 
 
 Of age. The influence of age on the respiratory products has 
 
 been studied by Andral and Gravarret, who found that the 
 quantity of carbonic acid which is daily excreted increases on 
 an average to the fortieth or forty-fifth year, and apparently in 
 a direct ratio with the development of the muscular system. 
 For equal bodily weights, however, children of nine or ten 
 years of age exhale nearly double as much carbonic acid as 
 adults (Scharling). 
 
 Of sex. With regard to sex, the experiments of Scharling as well 
 
 as those of Andral and Gravarret show that males from child- 
 hood upwards exhale more carbonic acid than females. This 
 influence of sex has been found to be equally well marked in 
 man and the lower animals. 
 
 Regnault and Reiset found that lean animals consume 
 more oxygen and exhale more carbonic acid, than very fat 
 ones, a result which is in accordance with the observations 
 made by Bidder and Schmidt, that fat .animals excrete far 
 less bile than lean ones. 
 
 Tabular (338.) We may conclude this part of the subject with the 
 
 normal re- 6 fU wm g table, which is based on Scharling's observations, 
 
 lations of an( j w hich may be regarded as showing the normal numerical 
 carbonic J 
 
 acid. relations of the excreted carbonic acid. 
 
RESPIRATION. 479 
 
 
 
 
 
 Amount of carbonic 
 
 Subject. 
 
 Age. 
 
 Woirri,*- Carbonic acid ex- 
 /vei nt. haled lu Qne hour 
 
 acid exhaled in one 
 hour for each 1000 
 
 
 Years. 
 
 Kilogrammes. 
 
 Grammes. 
 
 grammes weight. 
 G-ammes. 
 
 Man . 
 
 35 
 
 65-50 
 
 33-530 
 
 0-5119 
 
 Youth . 
 
 16 
 
 57-75 
 
 34-280 
 
 0-5887 
 
 Soldier 
 
 28 
 
 82-00 
 
 36-623 
 
 0-4466 
 
 Girl . 
 
 17 
 
 55-75 
 
 25-342 
 
 0-4546 
 
 Boy . 
 
 9f 
 
 22-00 
 
 20-338 
 
 0-9245 
 
 Girl . 
 
 10 
 
 23-00 
 
 19-162 
 
 0-8831 
 
 The numbers obtained by Andral and Gravarret differ 
 slightly from Scharling's. They find, that an adult man ex- 
 hales on an' average from 38-5 to 40*3 grammes of carbonic 
 acid in an hour ; an adult female, when not pregnant, from 
 22-0 to 23*8 grammes ; during pregnancy, 29 f 3 grammes ; 
 and after the cessation of menstruation, from 27*5 to 31-2 
 grammes. Although Scharling's numbers include the pro- 
 ducts of perspiration with those of respiration, they are pro- 
 bably (from the mode in which he conducted his experiments), 
 the more accurate of the two. 
 
 Since the above paragraphs were written, I have received 
 Dr. E. Smith's memoirs, which have been already referred to. 
 After noticing the discrepant results of previous inquirers, he 
 gives his own results obtained from experiments made upon 
 himself and upon three friends, all men in the prime of life, 
 the ages being 38, 48, 26, and 33 years. The following are 
 the total average results in 24 hours, 
 
 Carbonic Acid. Carbon. 
 
 In quietude . . 26-193 oz. = 7-144 oz. 
 
 With gentle exercise . 31-824 = 8-680 
 
 With exercise (on the treadmill) 43-000 = 11-700 
 
 or as a general average, 33*67 oz. of carbonic acid, and 9-18 
 oz. of carbon. Of the 26-193 oz. expired in a state of rest, 
 1950 grains were expired in the six hours of the night. The 
 proportion per minute in the night and the day is 1 to 1*84. 
 
 (339.) The peculiarities presented by the respiratory rela- inspiration 
 tions in different classes of animals, may be here briefly noticed. r 
 
 With reference to the mammalia, we find from the re- 
 
480 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 searches of Eegnault and Eeiset (which in many respects 
 have been confirmed by the subsequent investigations of 
 Bidder and Schmidt), that the differences which have been 
 observed in the respiratory relations of the herbivora and 
 carnivora, do not depend upon any difference in their or- 
 ganisation, 'but are solely due to the influence of their food. 
 For in the same manner as we observe that the urine of the 
 carnivora, when fed upon vegetables, becomes similar to that 
 of the herbivora, and that conversely the urine of the herbi- 
 vora may be made, by feeding them on animal food, to 
 resemble that of the carnivora (see p. 346), so also we find 
 that carnivora, which are made to live principally on amy- 
 laceous matters, exhibit the same respiratory relations as the 
 herbivora, and conversely. Carnivorous animals absorb more 
 oxygen and exhale more carbonic acid and nitrogen than 
 herbivorous animals. 
 
 The respiratory activity is very different in different kinds 
 of birds ; small singing birds, which are constantly flying about 
 and always in a state of activity except when asleep, con- 
 suming ten times as much oxygen, and exhaling nearly ten 
 times as much carbonic acid (weight for weight), as the 
 common hen, which seldom flies, and consumes little more 
 oxygen than rabbits, and less than dogs. These differences 
 are clearly brought out in the following table, which is based 
 upon Eegnault and Eeiset's observations. (The small birds 
 were green-finches, cross-bills, and sparrows, and the numbers 
 are mean results.) 
 
 Animals. 
 
 * Food. 
 
 Of 100 parts of 
 absorbed oxygen 
 there pass into the 
 carbonic acid 
 
 For 1000 grammes weight in one hour 
 
 Consumed 
 oxygen 
 
 grammes. 
 1-053 
 11-473 
 
 Exhaled 
 carbonic 
 acid 
 
 grammes. 
 1-320 
 11-879 
 
 Exhaled 
 nitrogen 
 
 grammes. 
 0'0079 
 0-1296 
 
 Hens . . 
 
 Small birds . 
 
 Oats. 
 
 Moderately 
 Sparingly 
 
 87-7 
 75-3 
 
 During incubation, the eggs of birds exhale carbonic acid, 
 
RESHBATION. 481 
 
 and absorb more oxygen than is contained in the exhaled In eggs, 
 carbonic acid ; and in proportion as the embryo becomes more 
 fully developed, a larger amount of oxygen is absorbed from 
 the air, and more carbonic acid given back to it. Even in 
 fresh, unincubated eggs, a similar change takes place, although 
 in a less marked degree. 
 
 It is unnecessary to state more regarding the respiration of i n rep tiics 
 reptiles and amphibians, than that (as might have been as- and am ' 
 
 / m phibians. 
 
 sumed a priori), the interchange of gases in the lungs is most 
 abundant in those of most active habits. The lizard, for 
 example, absorbs more than twice as much oxygen as the 
 frog, weight for weight. The respiratory process is on the 
 whole far less energetic in these animals than in mammals or 
 birds. 
 
 The respiration of gill-breathing animals (fishes, crustaceans, 
 &c.) has not been investigated in its general bearings by 
 any recent chemist ; indeed, almost all that we know regard- 
 ing the respiratory products of fishes (excepting in relation 
 to one or two special points) is due to Humboldt and Provencal, in fishes. 
 They ascertained that the oxygen which is absorbed exceeds 
 that which is exhaled in the form of carbonic acid (the latter 
 amounting to scarcely four-fifths, and often to only half the 
 former) ; that nitrogen is constantly absorbed in large quantity, 
 and that fishes, like other animals, transpire copiously through 
 the skin. They likewise ascertained that fishes are capable 
 of breathing in atmospheric air as long as their gills are kept 
 moist, the products of respiration being the same as when 
 they are breathing in water, which is a proof that respiration 
 in these water-breathing animals follows the same laws as 
 those which control atmospheric respiration : Baumert has 
 shown that in active fishes (like the gold-fish) the inter- 
 change of gases is far more energetic than in sluggish fishes 
 (like the loach). He has likewise investigated the respiratory 
 products of the pond-loach, a fish, which, in addition to its 
 branchical respiration, possesses an intestinal respiration, as 
 
 I I 
 
482 PHYSIOLOGICAL CHEMISTRY. 
 
 was shown many years ago by Ermann. He found that the 
 air which was eliminated through the intestinal canal contained 
 much less oxygen than the air which the fishes had swallowed ; 
 the oxygen had however been replaced by much less carbonic 
 acid than we usually meet with in branchial or pulmonary 
 respiration. Hence, while the oxygen which is absorbed by 
 the intestine passes into the blood, the carbonic acid to which 
 it gives rise is not eliminated by the intestine but by the gills, 
 and consequently these fishes exhale an excess of carbonic 
 acid as compared with the oxygen which they absorb from the 
 water. 
 
 The respiratory products of insects in their different phases 
 of metamorphosis have been especially studied by Kegnault 
 and Eeiset, and by Lehmann. *The variations in the degree 
 of animation in the motions of insects produce remarkable 
 differences in the quantity of carbonic acid which they ex- 
 crete ; and on that account, probably, the pupa exhales only 
 1-1 90th or 1-1 60th part of the carbonic acid which is exhaled 
 by the more active caterpillar, weight for weight. 
 
 Of animals possessing no special organs of respiration the 
 earth-worm is the only one which has been made the subject 
 of special investigation. Regnault and Reiset prove that the 
 respiration of this animal is very similar to that of the frog, 
 which (in addition to its pulmonary respiration) breathes 
 vigorously through its skin. They ascertained that one kilo- 
 gramme weight of these animals absorbed, in one hour, 
 0*1013 of a gramme of oxygen, and exhaled 0*0982 of a 
 gramme of carbonic acid ; the absorbed oxygen being to the 
 oxygen contained in the expired carbonic acid in the ratio of 
 100 to 77*5. 
 
 The following tabular view of the respiratory relations of 
 different classes of animals has been drawn up by Lehmann. 
 
RESPIRATION. 
 
 483 
 
 
 
 Proportion of 
 
 For 1000 pants (by weight) of the 
 animal in one hour. 
 
 Animal. 
 
 Food. 
 
 absorbed oxygen 
 in 100 parts of 
 carbonic acid. 
 
 
 Absorbed 
 oxygen. 
 
 Exhaled 
 carbonic 
 acid. 
 
 Exhaled 
 nitrogen. 
 
 Dogs . 
 Rabbits . 
 
 Flesh 
 Turnips. 
 
 74-5 
 91-9 
 
 1-183 
 
 0-883 
 
 1-211 
 1-116 
 
 0-0078 
 Q'0036 
 
 Hens . 
 
 Oats. 
 
 807 
 
 1-053 
 
 1-320 
 
 0-0079 
 
 Small birds 
 
 Oats. 
 
 75-3 
 
 11-473 
 
 11-879 
 
 0-1296 
 
 Frogs . 
 
 
 76-0 
 
 0-084 
 
 0-088 
 
 0-0005 
 
 Newts 
 
 
 82-4 
 
 0-085 
 
 0-096 
 
 
 Lizards 
 
 
 75-2 
 
 0-192 
 
 0-198 
 
 0-0025 
 
 Cockchafers 
 
 
 80-8 
 
 0-0195 
 
 1-1372 
 
 
 Silk-worm moths 
 
 
 78-2 
 
 0-899 
 
 0-960 
 
 
 Tenches 
 
 
 72-3 
 
 0-0143 
 
 0-0138 
 
 
 Gold-fish . 
 
 
 72-3 
 
 0-0409 
 
 0-0419 
 
 
 Earth-worms 
 
 
 77-5 
 
 0-1013 
 
 0-0982 
 
 
 In all these experiments the exhalations from the skin are 
 included with those of the lungs ; the carbonic acid exhaled 
 from the skin has however been shown by special observations 
 of Regnault and Reiset to be very trifling as compared with 
 that from the lungs, both in mammals and birds, and seldom 
 to amount to l-50th of the whole carbonic acid: but in the 
 amphibia this is by no means the case ; frogs in which the 
 lungs have been extirpated not only living for a long time, 
 but yielding almost as much carbonic acid and aqueous vapour 
 as if they had been uninjured. 
 
 (340.) Notwithstanding the investigations of Scharling, Respiration 
 Hannover, and other inquirers, our knowledge of the effects of m dlsease - 
 different diseases upon the respiratory products is still so 
 very deficient and indefinite, that it seems advisable to pass 
 the subject entirely over with the remark, that those who 
 wish to investigate it will find a full account of all the ex- 
 periments that have been made regarding it in the third 
 volume of Lehmann's Physiological Chemistry, pp. 376 382. 
 
 (341.) We shall conclude this chapter with a few remarks Origin of 
 upon the origin of the carbonic acid, and on the theory of bonic acid, 
 animal heat. We have already shown in different parts of this 
 volume, that various gases (carbonic acid, oxygen, and 
 nitrogen) are present, not only in the blood but in the 
 
 112 
 
484 PHYSIOLOGICAL CHEMISTRY. 
 
 lymph, chyle, and indeed in all the fluids of the body ; and 
 Lehmann has demonstrated by positive experiments that there 
 is not a single vital organ in the whole organism from which 
 we may not with the air-pump extract free carbonic acid, 
 nitrogen, and some traces of oxygen. The carbonic acid is, 
 at all events for the most part, fonned by the individual 
 organs and tissues in the exercise of their respective functions, 
 and is not primarily evolved in the blood. In insects this is 
 obviously the case, for in this class of animals there is no true 
 blood, nor (excepting the dorsal vessel) are there any true 
 blood-vessels ; the air comes directly in contact, through the 
 stigmata and tracheal ramifications, with every portion of the 
 tissues of the different organs; and as the experiments of 
 Newport and others show us that the amount of excreted 
 carbonic acid rises and falls in direct proportion to the 
 activity of the insects, it is clear that this gas must be formed 
 in the parenchyma of the organs themselves, and through 
 their vital energy. This fact alone would render it extremely 
 probable that in the higher animals also the greater portion 
 of the carbonic acid is likewise formed in the various 
 organs, and not in the blood. But independently of probabi- 
 lity, we have direct proof that this is the case in the investiga- 
 tions of Gr. Liebig, to which we have already referred (see 
 p. 405). He has distinctly proved that carefully prepared 
 frogs' muscles absorb oxygen and exhale carbonic acid so long 
 as their irritability lasts, that the latter is lost in irrespirable 
 gases, and finally that a muscle completely deprived of blood 
 continues to maintain this interchange of gases so long as it 
 retains its contractility. Here then we have a true respiration 
 taking place in a higher animal, without blood and without 
 special air-passages. As, moreover, these experiments show 
 that the muscles require the free access of oxygen in order to 
 preserve their contractility, it is clear that a large portion of 
 this gas, after being absorbed by the lungs, must be conveyed 
 in a free state through the blood and the walls of the capil- 
 laries into the muscles ; and consequently the blood serves the 
 
RESPIRATION. 485 
 
 double purpose, of conveying to the muscles the amount of 
 oxygen necessary for the performance of their functions, and 
 of carrying back the carbonic acid formed by this function ; 
 and we have an interchange of gases - in short, a respiratory 
 act taking place- in the tissues of the organs between the 
 parenchymatous juice and the blood in the capillaries. 
 
 We must not, however, conclude from the preceding obser- 
 vations, that the whole of the carbonic acid is formed in the 
 tissues of the organs. Previously to Barley's and to Meyer's 
 investigations (see note, p. 220), which have placed the matter 
 beyond all doubt, there were strong reasons for believing that 
 a part of the oxygen which is absorbed in the lungs enters 
 into chemical combinations while in the arterial blood. We 
 know, for example, that oxygen is absorbed by the blood in 
 far greater quantity than we should have expected from the 
 ordinary laws of absorption (see p. 220) ; that the absorption 
 of oxygen by the blood is not dependent on external pressure, 
 as would be the case if it were merely mechanical ; that the 
 modifications which the blood undergoes in its passage through 
 the pulmonary capillaries, after it has given off its carbonic 
 acid and absorbed oxygen, must be referred to chemical changes 
 in some of its constituents (see p. 219); and lastly, that 
 hsematin and hsemato'crystallin possess the property of com- 
 bining readily with oxygen (see pp. 95 and 215). The fact that 
 acetate- or tartrate of potash or soda (or any vegetable salt of 
 this class) when injected into the veins, becomes rapidly 
 oxidised and reappears in the urine as "a carbonate, indicates 
 that a certain portion of carbonic acid is formed in the arterial 
 blood ; and it is probable ttat many other substances are 
 similarly acted upon in the circulating fluid.* 
 
 (342.) The subject of Animal Heat is usually associated with Animal 
 that of respiration. Animal heat must not, however, be re- 
 
 * For further information on the subject of this paragraph, I may refer the 
 cader to a paper by Dr. E. Smith, On the Immediate Source of the Carbon 
 exhaled by the Lungs," published in the Philosophical Magazine for De- 
 cember 1859. 
 
 I I 3 
 
486 PHYSIOLOGICAL CHEMISTRY. 
 
 garded as a direct consequence of respiration, as was supposed 
 by Lavoisier and hrs followers, inasmuch as it is not specially 
 engendered in the lungs, but is for the most part the result of 
 the general oxidation which is going on through the tissues 
 in all parts of the body. 
 
 We are indebted to Gr. v. Liebig for the discovery of the 
 remarkable fact (which has since been independently confirmed 
 by Bernard and Walfarden), that so far from the lungs being 
 the chief seat of the production of heat, the blood is actually 
 cooled in passing through those organs, and is about 0-2 
 lower in temperature in the left, than in the right side of the 
 heart. As a certain amount of latent heat must be liberated 
 by the absorption of oxygen in t]ie lungs, the result must be 
 explained by this augmentation of temperature being more 
 than balanced by the exhalation of carbonic acid and aqueous 
 vapour. 
 
 Direct experiments, made with the object of comparing the 
 amount of animal heat with the heating power of different 
 kinds of food, show that at least one-twentieth of the heat 
 developed by an animal cannot be referred to the oxidation 
 or combustion of the food ; or, in other words, the oxidation of 
 the food cannot, so far as we at present know, produce more 
 than nineteen-twentieths of the actual heat.* Future in- 
 vestigations will probably clear up this discrepancy. The 
 small deficiency, which is still unaccounted for, may be 
 made up by the heat, which (as we learn from the thermo- 
 electric investigations of Becquerel and Breschet, and of 
 Helmholtz) is developed by the muscles during their contrac- 
 tion. There is also reason to believe that all nervous action 
 is accompanied by a slight development of heat. 
 
 * I quote these numbers on the authority of Lehmann (Handbuch d. Phys. 
 Chem. 2nd Ed. 1859, p. 385), but do not know how or by whom they were 
 obtained. Despretz found that in carnivorous animals (cats and dogs), from 
 76 to 80gof the animal heat might be referred to the oxidation (or combustion) 
 of the carbon and hydrogen of the food, while in herbivorous animals (rabbits 
 and guinea-pigs), the corresponding numbers were 86 88, in carnivorous 
 birds 75, and in granivorous birds 79g. 
 
487 
 
 CHAPTEE XX. 
 NUTRITION. 
 
 (343.) The study of the process of nutrition must be re- Investiga- 
 garded as constituting the true ultimate aim of all physiologico- iiminaiy to 
 
 chemical inquiries. In the preceding pages we began by con- 
 sidering the various organic and inorganic bodies of which the 
 living organism is composed, or which are formed within it 
 the organic substrata, as Lehmann terms them ; we then 
 noticed the various fluids of the body, and the parts which 
 both the solids and fluids perform in the accomplishment of 
 the most essential functions of animal life ; and we have en- 
 deavoured to determine the uses or functions of the four great 
 groups the protein-bodies, the fats, the carbo-hydrates, 
 and the mineral matters, within the animal organism. If we 
 have been successful in this endeavour, the reader will at 
 once perceive that these four essential adjuncts in the meta- 
 morphosis of the animal body must also be contained in 
 those articles of food which are required for the renovation 
 and restoration of those particles which have been lost or 
 worn out, and for the due accomplishment of the vital 
 phenomena. 
 
 (344.) It is only comparatively recently that we have Necessity 
 learned from French and Dutch gelatin commissions, and J^ure of 
 
 from numerous independent observations on animals, that in the differ- 
 
 . ent kinds 
 
 order to supply the wants of the system food must consist 01 O f food in 
 
 a combination of these' four groups, and that animals which p^pdr- 
 
 are fed exclusively on food belonging to one of the groups, as tions. 
 for instance albumen or fibrin, perish under 'symptoms of 
 inanition exactly as if they had been deprived of all nourish- 
 
 I I 4 
 
488 PHYSIOLOGICAL CHEMISTRY. 
 
 ment.* As in the milk destined for the infant we find 
 representatives of each group in the casein, butter, sugar, and 
 various salts, so, for other periods of life, these nutrient 
 matters, whether derived from the animal or the vegetable 
 kingdom, must contain a due admixture of the four types ; 
 and in considering the nutritive value of any article of food 
 in any special case, we must further bear in mind that it not 
 only depends upon the proportion in which the four funda- 
 mental groups are combined, but also in part upon the indi- 
 
 * The researches of Dr. Hammond (see pp. 341-42), " On the nutritive value 
 and physiological effects of albumen, starch, and gum, when singly and exclu- 
 sively used as food," are so important, that although they prove more than the 
 mere statement that an admixture of the different groups of food is necessary 
 for the well-being of the animal economy, I give them here with little abridge- 
 ment. 
 
 " 1. Albumen may be assimilated into the system in such quantity as to furnish 
 a sufficiency of both nitrogen and carbon to the organism. 
 
 2. Under the use of an exclusively albuminous diet the nitrogenous consti- 
 tuents of the urine are increased over the ordinary average amount, though 
 not in proportion to the quantity of albumen absorbed into the circulation. 
 
 3. Either some other means than the urine exist for the elimination of nitrogen 
 from the system, or the excess (over two-thirds) is retained in the organism 
 even when the body is rapidly decreasing in weight. 
 
 4. The continual use of albumen as an article of food increases the proportion 
 of this substance (and of fibrin) in the blood, and in a short time causes it to 
 appear in the urine. 
 
 5. Whilst pure albumen cannot be regarded as of itself adequate to supply 
 the several wants of the system, there is no reason why, when associated with 
 suitable inorganic matters, it should not support both life and health. [I think 
 this statement is open to grave doubt.] 
 
 6. Starch may. be assimilated by the absorbents in more than sufficient quan- 
 tity to sustain the respiratory function. 
 
 7. Under its use the nitrogenous constituents of the urine are very much 
 reduced in amount, even below what would probably occur during inanition ; 
 and although starch is not capable of nourishing the tissues, it is yet serviceable, 
 independently of its heat-producing power, in retarding their destructive meta- 
 morphosis. 
 
 8. The continued use of highly amylaceous food causes the appearance of 
 sugar in the urine. 
 
 9. Under the use of such aliments, the nitrogenous constituents of the blood 
 are diminished, and the carbonaceous increased. 
 
 10. Gum is altogether incapable of assimilation, and therefore possesses no 
 calorifacient or nutritive power whatever, but is, on the contrary, a source of 
 irritation to the digestive organs." 
 
NUTRITION. 489 
 
 vidual requirements of the organism that is to be nourished, 
 and that it may thus vary with age, amount of bodily exercise, 
 &c., or in the case of domestic animals, with the object that 
 we have in view in feeding, whether, for instance, we are 
 training an animal for feats of speed or strength, whether we 
 are fattening it for the market, or whether we are endeavouring 
 to increase its quantity of milk. 
 
 (345.) In judging of the nutritive value of any kind of DigestL 
 food we must not overlook its digestibility. It is well known element* of" 
 
 that hard-boiled eggs, meat that has been boiled for a long the nutri- 
 
 3 tive value. 
 time, and hard cheese which is poor in fat and in salts, are 
 
 less easily digested than soft-boiled or fresh eggs, meat 
 steeped in vinegar, or moist fat cheese ; and that starch is 
 much more readily converted into sugar when boiled than in 
 the raw form. Hence articles of food of the same chemical 
 composition may have very different nutritive values. 
 
 (346.) As the nitrogenous constituents of the food (the Nitrogen 
 articles of food containing albumen, fibrin, casein, &c.) are 
 
 principally employed in the formation of the blood and the nutrient 
 reproduction of the tissues, it was at one time thought that 
 the quantity of nitrogen which any kind of food contained 
 might be taken as a measure of its nutritive value; and 
 almost all the ordinary kinds of food have consequently been 
 analysed with special reference to this constituent. Boussin- 
 gault has determined the per-centage of nitrogen in almost 
 all the vegetables commonly used as human food ; K. Dundas 
 Thomson has similarly analysed different varieties of bread 
 and flour ; Schlossberger and Dopping have done the same for 
 the fungi ; while Schlossberger and Kemp have made similar 
 observations on an enormous number of animal substances 
 (including the flesh both raw and cooked of mammals, birds, 
 fishes, crustaceans, and mollusks, eggs, varieties of milk and 
 cheese, &c.) The results of these investigators are given in 
 detail in Lehmann's Physiological Chemistry vol. iii. pp. 
 401 403. One of the most important of the conclusions to 
 
490 PHYSIOLOGICAL CHEMISTRY. 
 
 be drawn from these investigations is that the amount of 
 nitrogen in muscular fibre does not essentially differ through- 
 out the whole animal kingdom, the average per-centage of 
 nitrogen being about 13. 
 
 We cannot however judge directly from the amount of its 
 nitrogen regarding the nutrient value of any kind of food in 
 reference to the formation of blood and tissues, for the 
 nitrogen which is found depends in part upon the gelatigenous 
 matters, which probably contribute little or nothing to the re- 
 production of the tissues. 
 
 In addition to the nitrogen-analyses to which we have 
 already referred, we must mention that at Liebig's suggestion 
 Horsford analysed a large number of varieties of vegetable 
 food, in reference not only to their per-centage of nitrogen, 
 but also to that of their sulphur, ash, albuminous substances, 
 non- nitrogenous ingredients, and water; and as his non- 
 nitrogenous ingredients contain not only starch, but cellulose, 
 wax, &c., Krocker made a similar set of observations in 
 reference to the actual per-centage of starch, and from these 
 and some other determinations Liebig has constructed a table 
 which affords a general view of the proportion between the 
 albuminates and the non-nitrogenous nutrient substances 
 (fat, starch, and sugar) occurring in the most common articles 
 of human food (10 parts of the albuminates being taken as 
 the unit of comparison). As the non-nitrogenous matters 
 exert a different influence on the generation of heat, according 
 as they are fats or carbo-hydrates, we take their respective 
 amounts of oxygen as the measure of comparison between 
 them. In this way 10 parts of fat correspond, in reference 
 to the generation of heat, to about 24 parts of starch, and 
 sugar of milk and glycose are obviously reduced to the cor- 
 responding value of .starch by the deduction of a certain 
 quantity of water. On this supposition (that is to say, 
 reckoning all the non-nitrogenous constituents as if they were 
 solely starch) the ratio of the plastic to the non-nitrogenous 
 
NUTRITION. 
 
 491 
 
 constituents ol food is as follows in the different articles in 
 
 the subjacent table : 
 
 i 
 
 In Cows' milk . 
 
 Woman's milk 
 
 Lentils . 
 
 Horse beans . 
 
 Peas 
 
 Fat mutton . 
 
 Fat pork 
 
 Beef . . 
 
 Hare 
 
 Veal 
 
 Wheat-flour . 
 
 Oat-meal 
 
 Rye-meal 
 
 Barley . 
 
 White potatoes 
 
 Blue 
 
 Rice 
 
 Buckwheat-meal 10 
 
 (347.) Both every-day experience and chemico-physiological 
 observations show us that the best kind of food must contain 
 fat as well as carbo-hydrates. We have seen that under 
 favourable conditions the animal body is able to form fat 
 from the carbo-hydrates, but this production of fat seems to be 
 limited ; and further, we have shown that fat and sugar fulfil 
 distinct objects in the animal economy. Instinct teaches us to 
 combine highly amylaceous foods with fats (as for example 
 bread and butter, beans and fat bacon) ; and the increased 
 digestibility of such mixtures proves, no less than the 
 simultaneous occurrence of fat and sugar in the milk (the 
 normal type of food), that both substances are necessary as 
 independent ingredients of food : and even if one of these sub- 
 
 lastic. Non-nitrogenous "Roflr. nf 
 (Calculated as starch). 1 J atl , f . 
 
 {o.o f f the plastic 
 to the non- 
 10-4 milk-sugar n i tro . 
 
 10 40 genous 
 consti- 
 21 tuents of 
 
 10 22 
 
 10 
 
 23 
 
 10 
 
 27 
 
 10 
 
 30 
 
 10 
 
 17 
 
 10 
 
 2 
 
 10 
 
 1 
 
 10 
 
 46 
 
 10 
 
 50 
 
 10 
 
 57 
 
 10 
 
 57 
 
 10 
 
 86 
 
 10 
 
 115 
 
 10 
 
 123 
 
 10 
 
 130 
 
 The best 
 relative ad- 
 mixture of 
 the differ- 
 ent groups 
 of food. 
 
492 PHYSIOLOGICAL CHEMISTRY. 
 
 stances may serve (as for instance in the development of heat) 
 as a substitute for the other, this does not in any way militate 
 against the special utility of either. A series of accurate 
 experiments on the proportion in which the four great 
 nutrient groups should be combined, so as to form the food 
 best suited to the general want of the organism, is still a 
 desideratum. During the period of early life, when growth 
 is most rapid, we may fairly infer that woman's milk presents 
 the most suitable mixture,, and in this fluid we find 10 
 parts of plastic matter (casein) combined with 10 parts of 
 fat (butter), 20 parts of a carbo-hydrate (sugar), and 0*6 of a 
 part of salts. 
 
 Various experiments show that in order that an animal 
 should be properly nourished, its food must contain an 
 admixture of the four great groups ; in short that unless these 
 groups are combined life cannot be supported. Thus, for 
 instance, Letellier found that when turtle-doves were fed 
 solely on protein-substances and sugar they gradually suc- 
 cumbed under the same symptoms as would have occurred if 
 they had been deprived of all solid food. If all the different 
 groups are present in the food, and one of them should 
 preponderate greatly over the others, nutrition will not go on 
 properly, as Boussingault ascertained on attempting to feed a 
 cow on potatoes and beet-root alone. 
 
 It must further be borne in mind, that there is no single 
 fixed proportion of the four groups suitable for all conditions 
 of life, even in the same individual. The proportions vary 
 in the infant, the young child, and in the adult ; and (to a far 
 greater extent) in different kinds of animals. The experiments 
 of Crusius * show that in the cow the nutritive value of the 
 milk is very different during different periods of lactation ; 
 and Becquerel and Vernois (see p. 281) recognise similar 
 differences in human milk. 
 
 We have seen that cows' milk contains relatively less sugar 
 
 * Journ. f. prakt. Ch. vol. Ixviii, pp. 1_23. 
 
NUTRITION. 493 
 
 and more fat and casein than woman's milk ; that asses' milk 
 contains very little casein but much sugar and far more fat ; 
 and that bitches' milk contains an excess of casein with mere 
 traces of sugar. There can then be no doubt that the require- 
 ments of the animal organism must present differences in the 
 admixture of the nutrient matters, but at present we are quite 
 unable to calculate with exactness the composition of the 
 food which is best adapted for each special organism. 
 
 (348.) We are better prepared to answer the following The neccs- 
 question, What are the absolute quantities of food which are tkyoffood 
 requisite for the maintenance of life, and for the energetic 
 accomplishment of all its functions ? There are two methods 
 by which we may determine the necessary amount of food. 
 The first consists in experimenting on oneself or upon 
 animals with the smallest possible quantities of differently 
 mixed food, until we have been able to find the suitable 
 amount and the most correct proportions for each individual 
 case, a troublesome and unsatisfactory mode of proceeding. 
 The second is based on the investigation and quantitative 
 determination of the excretions. If these afford a standard 
 measure of the metamorphosis of animal matter, and if we 
 are able, from their quantity and composition, to judge of 
 the daily loss which the animal body experiences, they ought 
 to give us the quantity and (to a certain degree) the chemical 
 composition of those substances which the organism requires 
 for the restoration of its effete matters. In order to 
 deduce trustworthy results from this method, we must be 
 careful to see that the organism on which we are experiment- 
 ing remains at a constant weight, and in all respects maintains 
 its normal state. By cutting off all supplies from without, 
 and then determining the quantities of matter lost by the 
 several excretions, we can calculate the minimum of food 
 necessary for the support of life, which is, however, very dif- 
 ferent from the quantity which is necessary to maintain the 
 animal in perfect health and in the full vise of its powers. 
 
494 PHYSIOLOGICAL CHEMISTRY. 
 
 The determination of the latter quantity is beset with diffi- 
 culties. If the absorption of digested matters were more 
 limited than it really is, and if no more nutrient matters 
 entered the blood than were necessary for the wants of the 
 system, we might perhaps make a calculation of the required 
 quantity from a comparison of the excretions and of the food 
 which had passed unchanged with the .faeces. Now we know 
 that the organism is not able to convert an unlimited quantity 
 of nutrient matter into blood. The experiments of Bous- 
 singault, Bidder and Schmidt, and von Becker show that 
 only definite quantities of fat, albuminates, or sugar can be 
 absorbed from the intestine in a given time. But though 
 there is a limit, it is a comparatively wide one, and numerous 
 experiments show that a much larger amount of nutrient 
 matter or chyle may be absorbed than is required for the 
 reparation of lost matter or for the accomplishment of the 
 different purposes of life. The excess that is thus absorbed 
 enters as superfluous matter into the blood, where it is not 
 employed either for the restoration of lost materials or for 
 the increase of mass of the body, or indeed for the accom- 
 plishment of any apparent object, but is again given off to 
 the external world after having undergone certain changes 
 which facilitate its excretion. To this excessive quantity of 
 food, much of which is superfluously absorbed, Schmidt has 
 applied the phrase, Luxus- consumption. The great difficulty 
 consists in our being unable accurately to determine the 
 mean which will give the organism neither too little nor too 
 much nourishment for the due performance of its various 
 functions ; and even this mean must obviously be liable to 
 great variations in the same individual, corresponding with 
 the degree of muscular and nervous energy. 
 
 The first of the two methods for determining the necessary 
 quantity of food gives safe practical results, provided we make 
 a. sufficient number of observations and apply the method of 
 statistics. We are indebted to Dr. Lyon Playfair for much 
 
NUTRITION. 
 
 495 
 
 useful information on the point. The following examples of 
 dietaries are extracted from a table attached to his memoir, 
 " On the food of man under different conditions of age and 
 employment." * 
 
 
 Weight of 
 food in 
 
 per week. 
 
 Weight of 
 nitroge- 
 nous in- 
 gredients. 
 
 Weight of 
 non-nitro- 
 genous 
 sub- 
 stances. 
 
 Weight of 
 mineral 
 matters. 
 
 Weight of 
 carbon. 
 
 Proportio 
 
 Carbon in 
 flesh- 
 formers. 
 
 i between 
 
 Carbon in 
 heat- 
 givers. 
 
 DIETARIES OF SOLDIERS AND 
 
 
 
 
 
 
 
 SAILORS. 
 
 
 
 
 
 
 
 
 English soldier . 
 
 378 
 
 36M5 
 
 127-18 
 
 4-92 
 
 71-68 
 
 
 3-66 
 
 in India . . . 
 
 261 
 
 34-15 
 
 103-19 
 
 2-39 
 
 66-32 
 
 
 3-55 
 
 English sailor (fresh meat) 
 
 302 
 
 34-82 
 
 102-89 
 
 3-17 
 
 70-55 
 
 
 3 70 
 
 (salt meat) . 
 
 290 
 
 40-83 
 
 132-20 
 
 603 
 
 87-40 
 
 
 3-94 
 
 French soldier . . . 
 
 347 
 
 33-24 
 
 12776 
 
 4-62 
 
 8525 
 
 
 4-72 
 
 DIETARIES OF THE YOUNG 
 
 
 
 
 
 
 
 
 Christ's Hospital, Hertford 
 
 216 
 
 17-16 
 
 61-27 
 
 2-47 
 
 39-18 
 
 
 4-21 
 
 London 
 Chelsea Hosp., Boys' school 
 DIETARIES OF THE AGED. 
 
 242 
 245 
 
 17-27 
 12-89 
 
 76-82 
 93-28 
 
 2-84 
 5-93 
 
 46-95 
 57-07 
 
 
 5-02 
 8-29 
 
 Greenwich pensioners . 
 
 269 
 
 24-46 
 
 122-21 
 
 3-54 
 
 72-43 
 
 
 .V46 
 
 Chelsea pensioners . 
 
 332 
 
 2995 
 
 112-04 
 
 4-65 
 
 78-03 
 
 
 4-80 
 
 OLD PAUPER DIETARIES. 
 
 
 
 
 
 
 
 
 St. Cutlibert's, Edinburgh. 
 City Workhouse 
 
 175 
 107 
 
 14-80 
 13-30 
 
 89-37 
 49-99 
 
 3-31 
 1-74 
 
 46-98 
 31-48 
 
 
 5-85 
 4-36 
 
 ENGLISH PRISON DIETARIES. 
 
 
 
 
 
 
 
 
 Class 2t, males . 
 
 206| 
 
 15 28 
 
 111-85 
 
 3-46 
 
 f>9-23 
 
 
 7'13 
 
 5J, 
 
 326 
 
 20'29 
 
 130-57 
 
 4'23 
 
 73-31 
 
 
 6'65 
 
 BENGAL PRISON DIETARIES. 
 
 
 
 
 
 
 
 
 Non-labouring convicts . 
 
 224 
 
 18-43 
 
 163-16 
 
 2-08 
 
 7635 
 
 
 7-62 
 
 Working convicts 
 
 296 
 
 28-16 
 
 191-12 
 
 2-97 
 
 91-07 
 
 
 5-96 
 
 Contractor's insuffic. diet . 
 
 167| 
 
 If -70 
 
 135-95 
 
 1-30 
 
 61-33 
 
 
 8-88 
 
 BOMBAY PRISON DIETARIES. 
 
 
 
 
 
 
 
 
 Prisoners not on hard labour 
 
 182 
 
 28-00 
 
 101-nO 
 
 2-03 
 
 68-81 
 
 
 4-52 
 
 on hard labour . 
 
 224 
 
 35-63 
 
 128-80 
 
 2-45 
 
 87-22 
 
 
 4-50 
 
 From the table from which we have extracted these 
 examples, Dr. Playfair draws the following conclusions : 
 " Taking the soldier and sailor as illustrating healthy adult 
 men, they consumed weekly about 35 ounces of flesh-formers, 
 and 70 74 ounces of carbon ; the relation of the carbon in 
 the flesh-formers to that in the heat-givers being 1 to 3*6. If 
 the dietaries of the aged are contrasted with this, it is found that 
 they consume less flesh-formers (25 30 ounces), but rather 
 more heat-givers (72 78 ounces) ; the relation of the carbon 
 
 * Edin. New Philos. Journal, 1854, vol. Ivi. p. 262. I may also refer the 
 reader to papers upon Prison and other Dietaries by Dr. E. Smith, in " The 
 "Transactions of the Society for the Promotion of Social Science, 1858," and 
 elsewhere. 
 
 f Convicted prisoners, exceeding 7 days, but not exceeding 21 days. 
 
 { Convicted prisoners, hard labour, for terms exceeding 4 months. 
 
496 PHYSIOLOGICAL CHEMISTRY. 
 
 in the former to that in the latter being about 1 to 5. The 
 young boy, about ten or twelve years of age, consumed about 
 17 ounces weekly, or about half the flesh-formers of the adult 
 man, the carbon being about 58 ounces weekly, and the re- 
 lations of the two carbons being nearly 1 to 5-5. The cir- 
 cumstances under which persons are placed influence these 
 proportions considerably. In workhouses and prisons the 
 warmth renders less necessary a large amount of food-fuel to 
 the body; while the relative amount of labour determines the 
 greater or less amount of flesh-formers. Accordingly it is 
 observed that the latter are increased to prisoners exposed to 
 hard labour. From the quantity of flesh-formers in food, we 
 may estimate approximatively the rate of change in the body. 
 A man weighing 140lb. has about *41b. of flesh [or rather of 
 matter equivalent to flesh] in the blood, 27 Jib. in his muscular 
 substances, &c. and about 51b. of nitrogenous matter in the 
 bones. These 371b. would be received in food in about eighteen 
 weeks ; or, in other words, that period might represent the 
 time required for the change of the tissues, if all changed with 
 equal rapidity, which is, however, not at all probable. Ail 
 the carbon taken as food is not burned in the body, part of it 
 being excreted with the waste matter. Supposing the re- 
 spirations to be 18 per minute, a man expires about 8*59 oz. 
 of carbon daily, the remainder of the carbon appearing in the 
 excreted matter." 
 
 According to Vierordt*, an adult male, to keep in good con- 
 dition, should take 120 grammes (or about 4 ounces) of albu- 
 minous matters, 90 grammes (or nearly 3 ounces) of fat, and 
 330 grammes (or about 10^ ounces) of amylaceous food 
 daily : the non-nitrogenous being to the nitrogenous food in 
 the ratio of 3*5 to 1. In addition to the above, there are 
 daily ingested about 32 grammes (or about 1 ounce) of salts, 
 about 2700 grammes (or about 84 ounces) of water, and 744 
 grammes (or about 23 ounces) of oxygen (in respiration). 
 
 * See his Grundriss der Physiologic des Menschen. 1860, p. 122. 
 
NUTRITION. 497 
 
 (349.) Boussingault has made a series of experiments on 
 ducks, which have a certain bearing upon an important factor 
 in the food question. He endeavoured to ascertain in the 
 case of these animals how much of various kinds of food they 
 were capable of absorbing in one hour. A tolerably full 
 account of the experiments may be found in the third volume 
 of Lehmann's Physiological Chemistry, pp. 412 414. From 
 them it follows that the different kinds of nutrient matter 
 are absorbed in very different ratios. Taking the protein- 
 matters as the unit, they stand thus, 
 
 Protein-matters . . . . .100 
 
 Grelatin 336 
 
 Fat .65 
 
 Starch ...... 401 
 
 Sugar 429 
 
 Lehmann states that, from other experiments, made upon 
 several kinds of animals, we may infer that for 1000 parts' 
 weight of the animal, there may be absorbed in one hour, 
 
 Protein-matters. . . . . .0*710 
 
 Fat . . . . . . . 0-465 
 
 Sugar ... . . . . 4-500 
 
 (350.) The influence of different kinds of food upon the Influence 
 blood (in the case of dogs), has been carefully studied by n \^ G 0( 
 H. Nasse. who has arrived at the following results : cpmposi- 
 
 tion or tno 
 
 1. After a purely animal diet, the blood-corpuscles exhibit blood. 
 a greater capacity for sinking; the blood itself presents a 
 darker colour, which becomes whitish after the abundant use 
 
 of fat ; the coagulation occurs somewhat more rapidly than on 
 a vegetable diet, and a continuous animal diet increases the 
 amount of fibrin, (as Lehmann also observed in his own case 
 after living exclusively on animal food,) and augments the 
 amount of the phosphates and of the salts generally. 
 
 2. Fatty food increases the quantity of fat in the blood, 
 
 K K ' 
 
498 PHYSIOLOGICAL CHEMISTRY. 
 
 even in the course of an hour after it has been taken, but the 
 excess rapidly disappears ; and the prolonged use of fatty 
 food does not seem persistently to increase the fat in the 
 blood. 
 
 3. The blood is of a somewhat lighter shade of colour when 
 the animals are kept upon vegetable food, and the sinking 
 capacity of the corpuscles is somewhat smaller ; the amount 
 of fibrin is not altered ; the fats and the phosphates are some- 
 what diminished. 
 
 4. After each meal the quantity of the solid constituents 
 of the blood increases to the ninth hour, when it again begins 
 to sink. 
 
 5. Continuous deprivation of food renders the blood some- 
 what pale in colour, retards its 'coagulation, and raises the 
 specific gravity both of the blood generally and of the serum ; 
 the fibrin is slightly and the salts are much increased. 
 
 Distribu- (351.) The next point we must attempt to decide is, 
 final f ro^ e re g ar ding ^ ne manner in which the final products of the 
 ducts of the nutrient matter that has served its purpose in the animal 
 excretions, economy, are distributed in the excretions. Although this 
 subject has been studied by several excellent observers, 
 amongst whom we may especially mention Barral, Valentin, 
 Boussingault, and Bidder and Schmidt, the fact that their 
 experiments have been made on very different kinds of 
 animals, living on various kinds of food, taken in various 
 quantities, prevents us from arriving at any definite con- 
 clusions, at all events regarding man. The very different 
 nature of the food of carnivorous and herbivorous animals is 
 in itself a sufficient reason for a want of uniformity in the 
 final products : in the carnivora, for example, a much larger 
 proportion of the fuel-products of the food passes off by the 
 urine and -the transpiration than in the herbivora, in con- 
 sequence of the latter always passing a large quantity of the 
 food from the intestine in an imperfectly digested state. 
 Our limited space will not allow of our noticing in detail 
 
NUTRITION. 
 
 499 
 
 the experiments to which we have alluded, and we must 
 content ourselves with three illustrations ; the first showing 
 the elements of 100 parts of the food consumed by a horse 
 and distributed in the excretions; the second showing the 
 same relations in the cow ; and the third showing the corre- 
 sponding relations in the case of a purely carnivorous animal, 
 the cat. For the first two of these investigations we are 
 indebted to Valentin and Boussingault, and for the third to 
 Bidder and Schmidt. The horse and cow had their ordinary 
 quantity of food, and the cat had for a week as much flesh as 
 it would eat.* 
 
 * Since writing the above lines, I have met with the following instructive tables 
 drawn up by Vierordt (Physiol. p. 192), in reference -to the ultimate composition 
 of the ingesta and egesta of man, his data being drawn from various trustworthy 
 sources, especially from recent observations by Volz (which I have not had an 
 opportunity of consulting.) The gramme is the unit in the following tables : 
 and the oxygen and hydrogen of the amylaceous food are calculated as water. 
 
 Daily Ingesta. 
 
 
 Totai. 
 
 Water. 
 
 C. 
 
 H. 
 
 N. 
 
 0. 
 
 Atmospheric oxygen 
 Albuminous food . 
 Fatty food . 
 Amylaceous food . 
 Water . 
 Salts 
 
 744-11 
 120 
 90 
 330 
 2635 
 32 
 
 183-18 
 
 64-18 
 70-20 
 146-82 
 
 8-60 
 10-26 
 
 18-88 
 
 744-11 
 28-34 
 9-54 
 
 
 3951 
 
 183-18 
 
 281-20 
 
 18-86 
 
 18-88 
 
 781-99 
 
 Daily Egesta. 
 
 
 otal. 
 
 Water. 
 
 C. 
 
 H. 
 
 N. 
 
 O. 
 
 Salts. 
 
 Respiratory products - 
 Cutaneous products - 
 Urine 
 Faeces 
 
 229-9 
 669-8 
 1766-0 
 172-0 
 
 330 
 
 660 
 178 
 128 
 
 248-8 
 2-6 
 9-8 
 20-0 
 
 3-3 
 3-0 
 
 ? 
 
 15'8 
 3-0 
 
 651-15 
 7-2 
 11-1 
 12-0 
 
 26 
 6 
 
 3837'7 
 
 2818 
 
 281-2 
 
 6-3 
 
 18-8 
 
 681-45 
 
 32 
 
 Comparing the H and O in the two tables, it appears that the difference of 
 the H in the two cases, viz. 12-56, must be oxidised and converted into water, 
 for which 100-6 of O is requisite (most of which is yielded by the atmosphere, 
 and the remainder from the oxygen of the food). In this way, 113-1 of water is 
 formed, which, added to the total 3837-7 'makes 3950-8, which closely accords 
 with the total ingesta. 
 
 K K 2 
 
500 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 In the horse : 
 
 Constituents of food. 
 
 Faeces. 
 
 Urine. Respiration and Perspin 
 
 Water 
 
 61 - 8 per cent. 
 
 5'9 per cent. 
 
 32-3 per cent. 
 
 Carbon 
 
 346 
 
 2'7 
 
 627 
 
 Hydrogen . 
 
 40-3 
 
 2'5 
 
 57-2 
 
 Nitrogen . 
 
 557 
 
 27-1 
 
 17-2 
 
 Oxygen . 
 
 41-4 
 
 1-0 
 
 57-6 
 
 Ash . 
 
 85-5 
 
 16-2 
 
 
 
 The food generally 55 -3 
 
 5-2 
 
 39-5 
 
 In the cow : 
 
 
 
 
 
 Constituents of food. 
 
 Milk. 
 
 Faeces. 
 
 Urine. 
 
 Respiration and 
 
 
 
 
 
 Perspiration. 
 
 
 per cent. 
 
 per cent. 
 
 per cent. 
 
 per cent 
 
 Water 
 
 10-2 
 
 34-4 
 
 10-0 
 
 45-8 
 
 Carbon 
 
 13-0 
 
 25'8 
 
 5'4 
 
 54-2 
 
 Hydrogen . 
 
 16-6 
 
 34-9 
 
 4-2 
 
 357 
 
 Nitrogen . 
 
 22-8 
 
 45-6 
 
 18-1 
 
 13-5 
 
 Oxygen 
 
 7'9 
 
 37 * 
 
 6'3 
 
 48-5 
 
 Ash . 
 
 6-1 
 
 53-9 
 
 43-1 
 
 3-1 
 
 The food general!} 1 
 
 10-3 
 
 34-4 
 
 99 
 
 45-4 
 
 In the cat : 
 
 Faeces. 
 
 Urine. Respiration and Perspiration. 
 
 Water 
 
 r aeces. 
 
 1-2 per cent. 
 
 urine. nesp 
 
 82-9 per cent. 
 
 irauun 
 
 15-9 
 
 I11U JTCI SJMI < 
 
 per cent. 
 
 Carbon 
 
 1-2 
 
 9-5 
 
 89-4 
 
 
 
 Hydrogen . 
 
 1*1 
 
 23-2 
 
 75-6 
 
 it 
 
 Nitrogen . 
 
 0-2 
 
 99-1 
 
 0-7 
 
 
 
 Oxygen 
 
 02 
 
 4'1 
 
 95-7 
 
 
 
 Sulphur . 
 
 50-0 
 
 50-0 
 
 
 
 
 Salts . 
 
 92'9 
 
 7-1 
 
 
 
 
 From these and other data of a similar kind, it appears 
 that far less water is absorbed from the intestinal canal of 
 herbivorous than from that of carnivorous animals. While 
 in the horse and in the cow only about half of the water is 
 absorbed, in cats and dogs as much as seventeen-twentieths are 
 absorbed: again, in the former animals, only from 15 to 
 20 of the water that has been absorbed or that has been 
 formed within the system, is removed by the kidneys, while 
 in the latter about 80^- passes off to the urine. 
 
 The fact that the absorbed carbon is excreted in far larger 
 quantities through the lungs in the herbivora than in the 
 carnivora (the carbon in the urine being to the carbon in the 
 
NUTRITION. . 501 
 
 respiratory products as 1 to 19 in the former, and as 1 to 9-5 
 in the latter), probably depends solely on the nature of the 
 food, and not upon any special relations of the organism ; for 
 while the carbo-hydrates which enter largely into the food of 
 the herbivora are completely resolved into carbonic acid and 
 water, and have yielded little or nothing to the urine, the 
 nitrogenous food of the carnivora is, for the most part, 
 ultimately reduced into urea, which contains a considerable 
 quantity (20-g-) of unoxidised carbon. 
 
 For the same reason we find that much less hydrogen is 
 eliminated through the kidneys in the herbivora than in the 
 carnivora; the ratio of the hydrogen excreted through the 
 urine to that eliminated through the lungs being as 1 to 23 
 in the herbivora, and as 1 to 3*3 in the carnivora. 
 
 The excretion of nitrogen is very different in herbivorous 
 and carnivorous animals ; the former often excrete by the 
 lungs and skin 40-g- of the nitrogen which they had absorbed 
 with the protein-bodies, while the latter rarely excrete more 
 than 1-g- by these channels. Indeed, Bischoff and Yoit's 
 experiments show that all their nitrogen is excreted as urea. 
 The cause of this difference is not altogether clear; but it 
 would almost seem as if the process of oxidation were so 
 energetic in the herbivora that a great part of their urea, 
 instead of being excreted in the form of urea, as in the case 
 of the carnivora, is still further oxidised a view which is in 
 some measure supported by the ordinary absence in their 
 urine of the earlier and less oxidised product of the de- 
 composition of the albuminates, namely, uric acid. It has 
 been suggested that the greater desquamation of the cuticle 
 and the more rapid growth and failing off of the hair in 
 the herbivora than in the carnivora, may partly account for 
 this difference, as these textures are rich in nitrogen ; as far 
 as I know, this view has not, however, been confirmed by any 
 trustworthy experiments or observations. 
 
 Our limits will not permit of our entering at any length 
 
 K K 3 
 
502 PHYSIOLOGICAL CHEMISTRY. 
 
 into the researches of Bidder and Schmidt, and the more 
 recent investigations of Bischoff and Voit, on the nutrition of 
 the carnivora. 
 
 The following table from Bidder and Schmidt is, however, 
 so important as showing the ultimate destiny (if we may use 
 such an expression) of the food, that it must not be omitted. 
 The experiments I., II., III., were made on an adult cat 
 weighing 3200 grammes, while IV. was made on a kitten 
 weighing 1170 grammes. We take the flesh that was con- 
 sumed (that is to say, its dried residue) as the unit, and 
 calculate the amount of solid matters which pass away in 
 the urine and faeces, the exhaled carbonic acid, and the 
 aqueous vapour; but exclude from our consideration the 
 water that has been taken, and that is separated by the solid 
 and fluid excretions. 
 
 I. has reference to the metamorphosis of tissue when the 
 minimum necessary quantity of food was taken, there being 
 free access to water. 
 
 II. has reference to the. greatest possible quantity of food, 
 with free access to water. 
 
 III. has reference to a normal flesh diet (that is to say, 
 one in which the weight of the body remains constant) without 
 water. 
 
 IV. has reference to another animal, with flesh and water 
 ad libitum. 
 
 i. n. in. iv. 
 
 Dried flesh . . 100-0 100-0 lOO'O 100*0 
 
 Absorbed oxygen . 167'0 166*0 167'3 166-2 
 
 Solid residue of the urine 31-3 30*4 30-6 31-4 
 
 Solid residue of the faeces 1*7 2-5 1-7 2-0 
 
 Exhaled carbonic acid 182-0 181-4 182-6 181'4 
 
 Exhaled aqueous vapour 137'6 76-4 152-6 1287 
 
 From this table we see that the flesh taken as food under- 
 goes in the body a species of analysis, which gives as 
 accurately defined values, as if it underwent in the laboratory 
 a process of fermentation or combustion, and we find that 
 
NUTRITION. 
 
 503 
 
 under all conditions one part of dry flesli is decomposed in 
 the living body, with the co-operation of 1-67 parts of oxygen, 
 into 0-31 of urinary matters, 0-02 of faecal matters, and 1-82 
 of carbonic acid. 
 
 Since the lean flesh that was used in these experiments 
 contained 19-56^ of albuminous and gelatigenous matters, 
 4-74 of fat, 1-g- of inorganic matters, and 74-7-g- of water, 
 while the solid residue of the urine, during such a diet, con- 
 tains on an average 85-5 g- of urea and 14-5-g- of salts (in which 
 are 2*3$ of sulphuric acid), and that of the faeces about 63 
 of biliary residue, the following balance may be struck 
 between the income and the expenditure of a carnivorous 
 animal, if we assume (which is very nearly the case) that for 
 every thousand grammes of its bodily weight, the animal 
 consumes daily fifty grammes of flesh. 
 
 An animal, for every 1000 grammes, 
 
 Water. 
 
 Albumen and gela- 
 tigenous matters. 
 
 Fat. 
 
 Salts. 
 
 50 000 gr. of flesh .... 
 21-125 oxygen 
 
 37-350 
 
 9-78 
 
 2-370 
 
 0-510 
 
 Total 71-125 gr. 
 
 
 
 
 
 An animal, for every 1000 grammes, 
 excretes in 24 hours, 
 
 Water. 
 
 Carbonic 
 Acid. 
 
 Urea. 
 
 Salts. 
 
 Intestinal 
 excretion. 
 
 Bile. 
 
 
 
 
 
 
 
 39-4G8 gr. of perspiration . 
 30761 urine 
 0-806 fasces 
 
 16-445 
 26-839 
 0-681 
 
 23-023 
 
 3-53 
 
 0'569 
 0-041 
 
 0-039 
 
 0-135 
 
 Total 71 -125 gr. 
 
 43-965 
 
 
 
 0-610 
 
 
 
 The excess of water ( = 6-615 grammes) in the excreta over 
 the ingesta obviously corresponds to the aqueous vapour 
 formed in respiration, while the increase of salts (0-100 of a 
 gramme) must be referred to the oxidation of the sulphur in 
 the albuminates. 
 
 The metamorphosis of flesh in the animal body is very 
 essentially modified by the simultaneous use of non-nitro- 
 genous food, such as fat or sugar. 
 
 Lehmann, basing his opinions chiefly on the observations 
 
 K K 4 
 
504 PHYSIOLOGICAL CHEMISTRY. 
 
 of Bidder and Schmidt, maintains that under all circum- 
 stances the use of fat diminishes the metamorphosis of the 
 nitrogenous constituents of the body ; thus, for instance (he 
 observes), during an entire deprivation of food, more urea is 
 excreted than when a purely non-nitrogenous diet is given. 
 We generally find that a carnivorous animal, when fed upon a 
 mixture of flesh and fat, excretes much less urea than we 
 should have calculated the ingested protein-compounds to 
 yield ; but occasionally rather more urea is excreted than on 
 a purely animal diet. The amount of urea must not, how- 
 ever, be taken as a perfectly correct measure of the amount of 
 metamorphosis of the nitrogenous constituents, since even in 
 adult and old animals, and of course in growing ones, a certain 
 amount of nitrogenous matter is deposited as additional tissue 
 and retained in the body ; and further we must not forget that 
 if an excess of fatty food is given, a certain amount of nitro- 
 genous material is required for the formation of the fat-cells ; 
 and that on the other hand, under certain conditions, the fat 
 contributes to the formation of the nitrogenous tissues.* 
 
 * Bischoff and Voit have carefully studied the effects of different kinds of 
 food on the metamorphosis of the tissues of the dog. As far as I can under- 
 stand their conclusions (which occasionally seem somewhat contradictory), 
 regarding the use of fat as food, they are as follows : 
 
 1. The metamorphosis of the nitrogenous parts of the body, and the con- 
 sumption of flesh for their restoration, are not impeded by the use of fat. 
 
 2. Fat directly increases the metamorphosis of the nitrogenous tissues in 
 proportion to its quantity. 
 
 3. Nevertheless fat invariably checks the metamorphosis of the nitrogenous 
 tissue by a definite amount which exceeds the increased metamorphosis just 
 noticed. Although this influence of the fat in diminishing the metamor- 
 phosis is not in itself great, we find that the quantity of flesh which we give 
 simultaneously with fat, need not be more than i or j of what we should give 
 without fat, to keep the body at its normal weight. 
 
 4. The consumption of the fat in the body may be diminished or entirely 
 avoided by the addition of fat to the food. 
 
 5. The apparent paradox that the fat both diminishes the consumption of 
 the nitrogenous tissues and food, and at the same time increases the metamor- 
 phosis of the muscular tissue, may be explained in this way, that in all possi- 
 bility the fat is not at once and directly burned in the blood, but first undergoes 
 
NUTRITION. 505 
 
 (352.) The metamorphosis of the tissues in fasting animals Metamor- 
 has been carefully studied by Boussingault, Chossat, Bidder {^'issues 
 and Schmidt, Bischoff and Voit, and others. Different kinds during 
 of animals lose different relative amounts of weight before 
 they necessarily die of inanition, the loss ranging from 31 to 
 52 of the normal weight.* Carnivorous animals (cats) 
 succumb in about eighteen days, after losing 51'7-g- of their 
 weight: the average daily loss being 2*87^. Other animals 
 lose during inanition 4-2-g-, or about -^th of their bodily 
 weight; a number which coincides pretty nearly with the 
 daily amount of nitrogenous food which they require. In 
 Schmidt's experiments on cats, the loss of weight was tolerably 
 steady from the beginning to the end. From the first to the 
 eighth day it corresponded to the quantity of carbon that 
 was expired (0-56 to 0'58-g- of the weight of the body); 
 subsequently the amount of carbon which was excreted sank 
 less than the bodily weight ; but it was only during the last 
 two days that it fell very far below the loss of bodily weight. 
 
 The secretion of urine at first diminished in a far more 
 rapid proportion than the bodily weight, but afterwards, till 
 
 a metamorphosis in some other part (probably the liver), and occasions a removal 
 of the nitrogenous substances. 
 
 6. Sugar and starch act in precisely the same way as fat, but these carbo- 
 hydrates, notwithstanding that they contain less carbon and hydrogen than fat, 
 have a more powerful effect in checking metamorphosis than that substance ; 
 the reason probably being that they (especially sugar) are burned directly in 
 the blood. 
 
 7. Liebig's division of foods into plastic and respiratory, is fully confirmed 
 by their investigations. Nitrogenous substances are the only producers of 
 force (Krafterzeuger), that is to say, they alone, by their decomposition in the 
 animal body, give rise to the phenomena of motion ; while fat and the carbo- 
 hydrates, by their decomposition, produce no motor effects, but merely develope 
 heat. If we except a few organisms containing cellulose, all animal structures 
 which possess an independent form are constructed of nitrogenous materials. 
 
 * Chossat found that rabbits (5 experiments) died when they had lost 
 37'4g of their weight ; guinea-pigs (5) when they had lost 33'Og ; turtle-doves 
 (15) when they had lost 37 '9~ ; domestic pigeons (20) when they had lost 4T6 ; 
 hens (2) when they had lost 52 -7, and a crow when it had lost 31-lg ; the 
 average of the 48 experiments being 39'7g ; or 2-5ths of the original weight. 
 
506 PHYSIOLOGICAL CHEMISTRY. 
 
 the sixteenth day, the loss proceeded in each in almost the 
 same proportions ; the urine, like the carbonic acid, diminishing 
 considerably during the last two days. The urine was richer 
 than usual in phosphoric and sulphuric acids, but the 
 chlorides disappeared after the first few days. The ratio of 
 the sulphuric to the phosphoric acid remained constant 
 throughout the experiment. 
 
 Schmidt has calculated the loss of weight of the muscle and 
 fat, for each individual day, from the amount of the excre- 
 tions. It follows from these calculations (for which we have 
 not space) that the average loss of muscular substance whicli 
 the animals experienced in twenty- four hours was O611 of 
 their weight at the time, while the corresponding loss of fat was 
 0*422, and they yielded 2-16 of -carbonic acid, 1-6% of per- 
 spired and exhaled aqueous vapour, 0'2 Og- of urea, O008 of 
 sulphuric acid, 0*01 1-g- of phosphoric acid, G-029-g- of inorganic 
 urinary constituents, 0*08^- of dry faeces (containing 0*02^ of 
 biliary residue), and 2-24- of water separated by the kidneys 
 and rectum. 
 
 Both Chossat, and Bidder and Schmidt have attempted to 
 determine the amount of loss of each individual organ during 
 inanition. In one of the cats experimented on by the latter 
 observers it appeared that during the eighteen days' inanition, 
 the blood experienced the greatest loss, namely, 93 4 7^- of its 
 original weight ; next in order was the pancreas, which lost 
 85-4-g-; the loss of fat was 80*7^, that of the muscles and 
 tendons 66'%, that of the brain and spinal cord 37'6-J, and 
 that of the bones 14*3^-; the loss experienced by the kidneys 
 was the least, being only 6'2-g. Hence the chief loss of 
 weight in the body is mainly due to the destruction of the 
 muscular tissue, the blood, and the fat. 
 Effect of (353.) The effect of the entire abstraction of water from 
 
 tion of the food has been studied by Bidder and Schmidt* on the dog, 
 water. 
 
 * Arch. f. phys. Heilk. vol. xii. pp. 61 73, and yol. xiii. pp 508 21. See 
 
NUTRITION. 507 
 
 by Falck and Scheffer* on the dog and on the pigeon, and by 
 Kunde on the frog. The following are the principal results at 
 which they have arrived: The animals took much less food 
 than when they were allowed to drink, and consequently their 
 excretions were considerably diminished. During a twelve 
 days' thirst a dog discharged 60 grammes of urine on the 
 first day, 24 grammes on the seventh day, and only 7 
 grammes on the twelfth day ; the skin peeled off, and the 
 hair (and in birds, the feathers) fell off; the excrements were 
 either viscid or hard. The excreta far exceeded the ingesta, 
 and hence there was a rapid diminution of the bodily weight. 
 In the absence of water pigeons lost daily 3-7-g- of their weight, 
 and from the twelfth to the thirteenth day (when they died) 
 4'6-g-. On an examination of the organs after death, the 
 greatest loss of weight was found to have been incurred by 
 the muscles, the skin, and the fat, while the brain, eyes, and 
 spleen were hardly affected. 
 
 (354.) We have hitherto considered the process of meta- 
 morphosis in adult animals. If we investigate the question in 
 growing animals the difficulties of the problem are so much 
 increased that we shall omit this portion of the subject alto- 
 gether. 
 
 We m ay here introduce a notice of one or two of the most The intes- 
 important results at which Bidder and Schmidt have arrived, J^ a a J mea- 
 
 in reference to the metamorphosis of the tissues. We have sure of the 
 
 1 metamor- 
 
 seen in the second part of this volume that the following phosis. 
 numerical data have been established with a fair amount of 
 certainty, partly from direct observation, but chiefly from 
 experiments on dogs. 
 
 An adult nian weighing 64 kilogrammes (or 10 stone) 
 secretes in twenty-four hours about 1600 grammes of saliva 
 containing 15 grammes of solid matters, 1600 grammes of 
 
 also Scheffer, De animalium, aqua iis adcmpta, nutritione. Diss. inaug. Mar- 
 burgh, 1852. 
 
 * Zeitsch. f. wiss. Zool. vol. viii. pp. 46686. 
 
508 PHYSIOLOGICAL CHEMISTRY. 
 
 bile with 80 of solid constituents, 16,900 grammes of gastric 
 juice with 91 grammes of solid constituents, 4600 grammes 
 of pancreatic juice containing 113 grammes of solid matters, 
 and 200 grammes of intestinal juice containing 3 grammes 
 of solids. Hence in the course of twenty-four hours digestive 
 fluids to the extent of 24,900 grammes (consisting of about 
 24,600 grammes of water and 300 grammes of solids) are 
 separated from the blood, poured into the intestine, and for the 
 most part are again absorbed. Now, since the body of a man 
 weighing 64 kilogrammes contains about 44 kilogrammes 
 (or 44,000 grammes) of water and 20 kilogrammes (or 20,000 
 grammes) of solid constituents, it follows that at least half of 
 the water, but only about -^ of the solids, are daily poured 
 into the intestine. 
 
 The daily amount of hydrochloric acid contained in the 
 gastric juice is ' calculated by Schmidt at 3*392 grammes, 
 which requires the decomposition of 5-436 grammes of salt. 
 If the b,ody contains 10 kilogrammes (or about 22 Ibs.) of 
 blood with 0'421-g- of chloride of sodium, about an eighth 
 part of the whole of this constituent must be decomposed 
 in order to yield its due supply of acid, while 2-881 grammes 
 of free soda are liberated. 
 
 The following investigations are of importance, as illustrat- 
 ing the connection between the secretion of bile and the 
 respiratory and urinary products. A dog living on mixed 
 food for every kilogramme's weight oxidizes in twenty-four 
 hours 8-6 grammes of carbon, and during the same period 
 secretes 1 gramme of solid biliary matter, and 0-5 of a 
 gramme of the carbon, contained in the latter, returns from 
 the intestine to the blood ; hence it follows that from 5 to 6 
 of the expired carbon has to go through the stage of bile- 
 formation, or in other words, that proportion of expired 
 carbonic acid takes its origin from the bile. This proportion 
 remains tolerably fixed during a flesh diet, but if a great 
 excess of animal food is given the biliary secretion increases 
 
NUTRITION.. 509 
 
 in a greater proportion than the respiratory products. During 
 the use of highly amylaceous food the oxidation of the biliary 
 constituents into carbonic acid is impeded, and the amount of 
 expired carbon considerably exceeds the quantity passing 
 through the bile. When the mineral constituents of the food 
 are much increased the biliary secretion is relatively more 
 augmented than the respiratory products : but during starva- 
 tion the former is more diminished than the latter. Scarcely 
 3^- of the nitrogen which is contained in the urinary con- 
 stituents passes through the bile (as taurine and glycine), 
 while from 54 to 86^ of the sulphur takes that course ; under 
 no conditions, however, does the whole of the sulphur pass 
 through the stage of bile. In herbivorous animals scarcely 
 two-thirds of the glycine contained in the hippuric acid are 
 derived from the glycocholic acid of the bile. 
 
 Bidder and Schmidt further determined the amount of 
 the different elements, of the water, and of the salts con- 
 tained in a carnivorous animal (a young cat, weighing 1505 
 grammes). 
 
 In 100 parts there were contained 32-039 of solid consti- 
 tuents ; and in a kilogramme's weight (1000 grammes) there 
 were contained about 679*61 grammes of water, 148*72 
 grammes of carbon, 20*19 grammes of hydrogen, 35*45 
 grammes of nitrogen, 54*78 grammes of oxygen, 2*43 
 grammes of sulphur, 1*88 grammes of sodium, 1*51 grammes 
 of chlorine, 51*02 grammes of earthy phosphates, including 
 about 0*4 of a gramme of iron, and 4*41 grammes of other 
 salts, including 2*12 grammes of phosphoric acid. 
 
 From the above (and other) data, Bidder and Schmidt 
 calculate that a dog fed with flesh gives off 2*25 grammes of 
 water by perspiration and respiration, and 5*97 grammes by 
 the urine and faeces (and therefore on the whole 8*22 parts) 
 for every 100 grammes of water which it contains ; while 23*25 
 grammes are effused into the intestine with the digestive or 
 chylopoietic fluids. Hence the intermediate circulation of 
 
510 PHYSIOLOGICAL CHEMISTRY. 
 
 water into the intestine involves nearly a fourth part of the 
 whole of the water in the body, and is nearly three times as 
 abundant as the final excretion from the system in the form 
 of perspiration and respiration. If, on the other hand, we 
 consider the blood, we find that in twenty-four hours about 
 27*9 of its water is entirely removed from the body, while 
 79'Og- is effused into the intestinal canal. Of every 100 
 parts of salts in a dog fed with flesh there are in twenty-four 
 hours 5-3 given off to the external world, while 8*5 parts are 
 effused with the digestive fluids over the surface of the 
 intestinal canal ; while of 100 parts of blood-salts 21 -2 parts 
 are completely excreted in twenty-four hours, and 34' 1 parts 
 are conveyed into the intestine.- Of every 100 parts of carbon 
 in the body 4'26 parts are daily separated by the respiration 
 and urine, while only 1*31 parts pass into the intestine (of 
 which 0-376 proceeds from the bile); and a similar ratio 
 holds good for the hydrogen. Of every 100 parts of nitrogen 
 in the body 3-89 parts are excreted, and only 1'28 parts pass 
 into the intestine (of which not more than 0-101 proceeds 
 from the bile). Of every 100 parts of sulphur in the body 
 3*3 parts are daily excreted by the kidneys, while 2*6 parts 
 enter the intestinal juices (1-7 of which is derived from the 
 bile). Of 100 parts of the phosphoric acid of the soluble 
 phosphates of the body, there are daily eliminated 7*27 parts, 
 while 2 '9 are effused into the intestine. 
 
 The above are merely a few of the striking results to which 
 Bidder and Schmidt's ingenious and original mode of inves- 
 tigation has led them. To those who wish to pursue the 
 subject further, we would especially recommend the careful 
 study of their work, " Die Verdauungssafte und der Stoff- 
 wechsel," and of the chapter headed " Statistische Ueber- 
 sicht des Stoffwechsels," in the first volume of Funke's 
 Lehrbuch der Physiologic. 
 
 On the (355.) We shall conclude this fragmentary chapter with a 
 
 which cer- brief notice of the power which certain substances, as for 
 
NUTRITION. 511 
 
 instance alcohol and tobacco, seem to exert in modifying the stances 
 
 exert in 
 ordinary metamorphosis of the tissues. checking 
 
 The physiological effects of alcohol upon the human system 
 
 have been very carefully examined by Dr. Bocker and more . f the 
 
 tissues. 
 
 recently by Dr. Hammond. We shall give the conclusions at 
 which Dr. Hammond has arrived from a series of careful ex- 
 periments upon himself. 
 
 He had the three following objects in view in his investi- The phy- 
 gations regarding alcohol. J^fon ?f 
 
 1. To observe its effects upon a system in which the weight alcohol 
 of the body was maintained at a nearly uniform standard 
 
 by a sufficiency of food. 
 
 2. To ascertain its influence upon an organism where the 
 body lost weight from a deficiency of food. 
 
 3. To determine its action upon a system when the body 
 gained weight from an excess of food. 
 
 (1.) Having ascertained the state of his system in reference 
 to the various excretions, &c., when no alcohol was ingested, 
 and when the food was sufficient to keep the weight constant, 
 Dr. Hammond took four drachms of alcohol diluted with an 
 equal quantity of water at each meal, or twelve drachms 
 daily ; and he continued this course for five days. I give the 
 results of the experiment in nearly his own words. After the 
 use of sixty drachms of alcohol in five days, his weight 
 increased from an average of 226*40 Ibs., to an average 
 of 226 -85 Ibs., being '45 of a Ib. of difference. The car- 
 bonic acid and vapour of water in the expired air had re- 
 spectively decreased 1324*5 and 196*5 grains, the faeces 1*2 
 ounces, and the urine 3*4 ounces daily (its urea being 
 diminished 87*2 grains, its chlorine 37*6 grains, its phosphoric 
 acid 24*5 grains, and its sulphuric acid 13*4 grains). The 
 free acid and the uric acid were apparently not affected. 
 
 The general health was somewhat disturbed, there being 
 headache and increased heat of skin ; and the mental faculties 
 not being so clear as when no alcohol was taken. There was 
 
512 PHYSIOLOGICAL CHEMISTRY. 
 
 indisposition to any kind of exertion ; appetite variable ; 
 digestion not affected. 
 
 The metamorphosis of tissue and fat was evidently con- 
 siderably retarded, as is shown by the decreased amount of 
 urea, carbonic acid, &c. Dr. Hammond ascribes the dimi- 
 nution in the weight of the faeces mainly to the increased 
 assimilation of food induced by the alcohol. 
 
 As alcohol cannot be converted into tissue, the increase in 
 the weight of the body was probably owing to the three follow- 
 ing causes : 
 
 1. The retardation of the decay of the tissues. 
 
 2. The diminution in the consumption of the fat. 
 
 3. The increase in the assimilative powers of the system, by 
 which the food was more completely appropriated and applied 
 to the formation of tissue. 
 
 From the results of the foregoing experiments Dr. Hammond 
 concludes, that when the food is sufficient for the require- 
 ments of the system alcohol: is injurious, by exciting the 
 circulation and tending to induce a plethoric habit of body ; 
 its influence in this respect being the same as that of an 
 excessive amount of food. When, therefore, alcohol is taken 
 in addition to a sufficient quantity of food, its effects should 
 be counteracted by the employment of means for the acce- 
 lerated destruction of the tissues, as for instance, by increased 
 muscular exercise, or by the free use of water (see p. 298) ; 
 the action of chloride of sodium is also to some extent 
 antagonistic to that of alcohol. 
 
 (2.) Dr. Hammond reduced his daily food for five days to 
 such an extent as to induce a daily loss of weight, and a 
 certain amount of exhaustion, and then additionally took the 
 same quantities of alcohol as in his first experiment. Before 
 beginning the alcohol his weight decreased an average of -28 
 of a pound daily, falling in five days from 226-73 to 225-34 
 Ibs. Under the use of alcohol for five days this decrease 
 was not only overcome, but there was an actual average daily 
 
NUTRITION. 513 
 
 increase of -03 of a pound, the weight rising from 225*34 to 
 a mean of 225-50 Ibs. 
 
 The expired carbonic acid exhibited an average decrease of 
 729 grains, the aqueous vapour of 312 grains, the faeces of 
 19 of an ounce, and the urine of 1*37 ounces (the urea 
 being diminished 54 '5 grains, the chlorine 10*1 grains, the 
 phosphoric acid 8'7 grains, and the sulphuric acid 1*1 grain). 
 The acidity of the urine and the uric acid were slightly 
 increased. 
 
 The general condition of his system was never better. 
 
 " The good effects," he observes, " of alcohol in limiting 
 the waste of the body when the supply of food is not sufficient 
 to maintain the vigour of the system are here very evident, 
 and stand in marked contrast to its influence when an abund- 
 ance of food was ingested. The strength was not only 
 sustained, but the body gained weight. In short, the alcohol 
 had taken the place of the bread and meat omitted, and at 
 no apparent disadvantage to the general economy." 
 
 (3.) When the body was gaining weight from excess of food 
 he found that the weight was further increased by the use of 
 alcohol, which, as in the previous cases, diminished all the 
 products of excretion. During the five days on which this 
 experiment was continued, the general health was much 
 disordered, there being constant headache, disturbed sleep, 
 hot skin, quick (98), full, and bounding pulse, &c. 
 
 From a general review of his three sets of experiments he 
 arrives at the conclusion, " that alcohol increases the weight 
 of the body by retarding the metamorphosis of the old and 
 promoting the formation of new tissues, and limiting the 
 consumption of fat." 
 
 The respiratory and urinary excretions, and the faeces were 
 invariably diminished. These effects occurring when the 
 amount of food was below the quantity required to maintain 
 the weight of the body under the mental and physical exer- 
 
 L L 
 
514 PHYSIOLOGICAL CHEMISTRY. 
 
 cise taken, were productive of no deleterious results to the 
 system ; but when the food was sufficient to balance the 
 waste from the excretions, and still more so when an excess 
 of aliment over the demands of the system was ingested, the 
 health was disturbed, and actual disease almost induced. 
 
 " The use of alcohol, even in moderation, cannot therefore 
 be either exclusively approved or condemned. The labour- 
 ing man, who can hardly procure bread and meat enough to 
 preserve the balance between the formation and decay of his 
 tissues, finds here an agent which, within the limits of health, 
 enables him to dispense with a certain quantity of food, and 
 yet keeps up the strength and weight of his body. On the 
 other hand, he who uses alcohol when his food is more than 
 sufficient to supply the waste of tissue, and at the same time 
 does not increase the amount of his physical exercise, or 
 drink an additional quantity of water (by which the decay 
 of tissue would be accelerated), retards the metamorphosis 
 while an increased amount of nutriment is being assimilated, 
 and thus adds to the plethoric condition of the system, which 
 excessive food so generally induces." * 
 
 With regard to tobacco Dr. Hammond made two sets of 
 experiments; (1) when a sufficiency of food was taken to 
 keep up the weight and vigour of the body, and (2) when an 
 inefficiency of food was taken. It should be mentioned that 
 he is not in the habit of using tobacco in any form, and that 
 during these experiments he smoked 450 grains daily. He 
 finds : 
 
 1. That tobacco does not materially affect the excretion of 
 carbonic acid through the lungs, but that it lessens the 
 amount of aqueous vapour. 
 
 * Moleschott, a well-known German authority pn dietetics, some years ago 
 arrived at almost precisely similar conclusions regarding the moderate use of 
 alcohol by ill-fed, hard-working men. The subject is discussed in a very phi- 
 losophic spirit by Dr. Chambers, in his excellent work on " Digestion and its 
 Derangements." 
 
NUTRITION. 515 
 
 2. That it diminishes the amount of faeces. 
 
 3. That it lessens the quantity of the urine and the amount 
 of its urea and chlorine, but that it increases the amount 
 of free acid, and of the uric, phosphoric, and sulphuric 
 acids. 
 
 These results differ in several essential points from those 
 yielded by alcohol. 'The fact that the amount of carbonic 
 acid was not diminished would indicate that the consumption 
 of the fat of the body is not lessened by the use of tobacco. 
 The general metamorphosis of the tissues would seem to be 
 retarded, seeing that both the urea and the chlorine of the 
 urine are diminished (in the first set of experiments the mean 
 
 0- 
 
 daily diminution of urea and of chlorine was represented by 
 42*4 and 23*0 grains ; while in the second set the correspond- 
 ing numbers were 6 2 '5 and 15-0 grains) : but as the phos- 
 phoric and sulphuric acids are increased (in the first set the 
 mean increase being 24*2 and 4*4 grains, and in the second 
 set 30*2 and 8*3 grains), we can only explain the apparent 
 inconsistency in these results by assuming that there is an 
 increased oxidation of the phosphorus and sulphur of the 
 brain and nervous tissue generally, although the metamor- 
 phosis of the other nitrogenous tissues is lessened. 
 
 Tobacco resembles alcohol in these respects, that when the 
 food is sufficient to preserve the weight of the body it 
 increases that weight, and when the food is not sufficient 
 and the body in consequence loses weight, it restrains that 
 loss : but it differs from alcohol in being unattended with any 
 unpleasant effects upon the circulatory system, though its 
 action on the brain is apparent in increased nervous excite- 
 ment, followed by a pleasant feeling of ease and content- 
 ment. 
 
 Tea and coffee are usually believed to have a somewhat Physio- 
 similar effect to that which, as we have shown, is produced by Action of 
 alcohol and tobacco. tca - 
 
516 PHYSIOLOGICAL CHEMISTRY. 
 
 Bocker * made a careful series of observations upon him- 
 self, for the purpose of testing the effects of tea on the 
 organism. 
 
 Three series of experiments were made under varying con- 
 ditions, but they all coincided in the following particulars : 
 
 1. Tea in ordinary doses has not any effect on the amount 
 of carbonic acid expired, the frequency of the respirations, or 
 of the pulse. 
 
 2. When the diet is insufficient, tea very considerably 
 limits the loss of weight thereby entailed. 
 
 3. When the diet is sufficient the body is more likely to 
 gain weight when tea is taken than when not. 
 
 4. Tea very much diminishes the loss of substance in the 
 shape of urea. 
 
 5. Tea very much lessens the quantity of faeces. 
 
 6. The loss by perspiration is also limited by tea. 
 
 Dr. Edward Smith has recently arrived at certain con- 
 clusions which are the very reverse of those of Bocker. He 
 maintains that tea increases the amount of carbonic acid (and 
 here he is likewise opposed to other observers ; see p. 477), 
 and that it actually accelerates the waste of the tissues. It 
 is to be trusted that this discrepancy of opinion between two 
 good observers may lead to this important question being 
 further examined and definitely settled. 
 
 Of coffee. The action of coffee on the organism has been carefully 
 studied by Dr. Julius Lehmann.f He has investigated the 
 separate actions of the different constituents of the coffee- 
 bean, viz. : caffeine (identical with theeine) and empyreumatic 
 oil, as well as of their mixture. The point that mainly 
 concerns us in reference to the present subject, is (1) that 
 coffee protracts the decomposition of the tissues, and (2) that 
 the protraction is chiefly caused by the empyreumatic oil, 
 
 * Archiv des Vereins f. gemeinschaftlichen Arbeiten 1853 ; or Chambers 
 op. cit. p. 246. 
 
 f Ann. d. Ch. ti. Pharm. vol. Ixxyii. p. 205. 
 
NUTRITION. 517 
 
 and that the caffeine only causes it when it is taken in larger 
 quantities than usual. 
 
 For further information on this subject the reader may 
 consult Dr. Chambers's remarks on " Arresters of Metamor- 
 phosis," in the work already referred to. 
 
518 
 
 EXPLANATION OF THE PLATES. 
 
 PLATE I. 
 
 Fig. 1. Oxalate of lime in the form in which it most commonly 
 
 appears in ordinary deposits. 
 Fig. 2. (a.) Oxalate of lime, (.) Carbonate of lime, deposited from 
 
 the urine of the horse. This form occasionally presents 
 
 itself in alkaline human urine, (c.) Urate of soda, from 
 
 a urinary sediment. We thus see that dumb-bell crystals 
 
 do not of necessity imply the presence of oxalate of lime. 
 
 See also Plate III. Jig. 4, where uric acid is represented 
 
 in the same form. 
 
 Fig. 3. Margaric acid, deposited from an alcoholic solution. 
 Fig. 4. Stearic acid, deposited from an alcoholic solution. 
 Fig. 5. (Misprinted^. 3 in p. 16.) Sebacicacid. deposited from a 
 
 hot solution. 
 Fig. 6. Lactate of lime, obtained from pure lactic acid and carbonate 
 
 of lime, and crystallised from a hot aqueous solution. 
 Fig. 7. Cholic acid, obtained by treating glycbcholate or taurocholate 
 
 of soda with caustic potash or baryta. . 
 
 Fig. 8. Glycine, obtained by the digestion of gelatin with caustic 
 
 potash, and crystallised from water. 
 
Plate 1 . 
 
 ,-j 
 
 F"^ 
 
 w A *^ 
 
 r I 1 
 
 H.Sinlhere PiMisJw loridaru Bailhav BrnUicrs, Wetr Yor~k.^ -. 
 
EXPLANATION OF THE PLATES. 
 
 PLATE II. 
 
 Fig. 1. Leucine, obtained by the digestion of albumen in concen- 
 trated sulphuric acid. 
 
 Fig. 2. Creatine, obtained from beefby Liebig's method, and crys- 
 tallised from hot water. 
 
 Fig. 3. Creatinine, obtained from creatine by digestion with hydro- 
 chloric acid, from which it is separated by- hydrated 
 peroxide of lead, and crystallised from a hot aqueous 
 solution. 
 
 Fig. 4. Urea from human urine ; crystallised slowly from an aqueous 
 solution. 
 
 Fig. 5. Nitrate of urea. 
 
 Fig. 6. Allantoine from calves' urine, recrystallised from hot alcohol. 
 
 Fig. 7. Cystine, obtained from a calculus, and crystallised from an 
 ammoniacal solution. 
 
 Fig. 8. Taurine from ox-bile, crystallised from a boiling aqueous 
 solution. 
 
lllicaULifi'6 L'uJbUsher London, ;.lliulliiar& Brothers, Hew Yorfa.^* 
 
522 EXPLANATION OF THE PLATES. . 
 
 PLATE III. 
 
 Fig. 1. Hippuric acid, crystallised from water. 
 
 Fig. 2. Glycocholic acid obtained by treating glycocliolate of soda 
 
 with sulphuric acid, and crystallised from a spirituous 
 
 solution by the addition of ether. 
 Fig. 3. Glycocholate of soda, from ox-bile, crystallised from an 
 
 alcoholic solution by the addition of ether. 
 Fig. 4. Uric acid in various forms. 
 Fig. 5. Urate of soda, obtained artificially by the digestion of pure 
 
 uric acid with phosphate of soda. See also Plate I. jig. 2. 
 Fig. 6. Urate of ammonia obtained by treating the preceding salt 
 
 with hydrochlorate of ammonia. 
 
TLJlailUerz 1'ubtLdur LonAorv: liaiJliarej .tirtfhcrs, Ni-w York. 
 
524 EXPLANATION OF THE PLATES. 
 
 PLATE IV. 
 
 Fig. 1. Stearin from mutton suet, crystallised from an ethereal 
 solution. 
 
 Fig. 2. Margarin, deposited from an alcoholic solution. 
 
 Fig. 3. Cholesterin, from the contents of a partly obliterated echino- 
 coccus-sac in the liver. In addition to the tablets of 
 cholesterin, the plate exhibits tufts of crystals of margaric 
 acid, roundish dark-coloured pigment-granules, and small 
 crystals of haematoidin. The whole extent is strewed 
 over with fat-globules and minute yellow amorphous 
 aggregations of bile and biliary products. 
 
 Fig. 4. Haematocrystallin. (a.) Blood-crystals from normal human 
 venous blood. (#.) Blood-crystals from the blood in the 
 heart of a kitten, (c.) Blood-crystals from the jugular 
 vein of a guinea-pig, (d.) Blood-crystals from the 
 jugular vein of a squirrel. I have selected these different 
 figures with the view of showing the various forms in 
 which this substance crystallises. 
 
 Fig. 5. A urinary sediment consisting of triple phosphates (phos- 
 phate of ammonia and magnesia), and of urate of ammonia, 
 thrown down by a specimen of urine that had undergone 
 alkaline fermentation, and which had been passed by a 
 man with paralysis of the lower extremities consequent on 
 disease of the spinal cord. 
 
4 h 
 
 PultUs^er L<nul<n< , R<rilliert> Rrotliers. New York.. 
 
526 EXPLANATION OF THE PLATES. 
 
 PLATE V. 
 
 Fig. 1. A urinary sediment consisting of the Tonila or Mykoderma 
 Cerevisice and Confervas, formed in diabetic mine after 
 exposure for a week to the air. 
 
 Fig. 2. The epithelium occurring in the " rice-water " discharges in 
 cholera. Crystals of triple phosphates are scattered 
 amongst the epithelial scales. Certain cell-like struc- 
 tures are also apparent. 
 
 Fig. 3 and fig. 4. I had originally intended to have given two 
 figures of the red corpuscles of the blood, one showing 
 them in the separate, and the other in the nummular form. 
 The figure I have selected shows, however, all that is re- 
 quired. A few colourless corpuscles are interspersed. 
 
 Fig. 5. The white or colourless corpuscles from a specimen of 
 leucaemic blood taken from a man with an enormously 
 enlarged spleen. They are here as numerous as the red 
 corpuscles. 
 
 Fig. 6. I had intended to have given a separate figure of the chyle- 
 corpuscles, but they so closely resemble the colourless 
 corpuscles exhibited in the preceding figure, that, on 
 further consideration, I deemed it unnecessary to do so. 
 
 Fig. 7. (a.) Milk from a healthy woman a week after delivery. 
 
 Fig. 7. (b.) Colostrum from a healthy woman twelve hours after 
 delivery. 
 
 Fig. 8. (a.) Healthy human pus. In the lower half of the figure 
 the pus-corpuscles are shown in their normal state ; in 
 the upper half they have been acted on by acetic acid. 
 
 Fig. 8. (#.) Pus that has undergone acid fermentation ; the result of 
 two months' exposure to the air. 
 
1 a> 
 
 5-6 
 
 ive, I'ubli. lift; 
 
 .', BcnRu're. 'Rrothrrs , New Tori* 
 

 
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