Ub aes a Th 0 < Fs S /Vyae lis M 16 Cornell University Library QH 345.M16 Til of vital phenomena, f i Date Due Library Bureau Cat. No, 1137 PHYSICAL CHEMISTRY OF VITAL PHENOMENA FOR STUDENTS AND INVESTIGATORS IN THE BIOLOGICAL AND MEDICAL SCIENCES BY J. F. MCCLENDON Assistant Professor of Physiology in the University of Minnesota PRINCETON UNIVERSITY PRESS PRINCETON LONDON: HUMPHREY MILFORD OXFORD UNIVERSITY PRESS 1917 b % He Pweg Copyright, 1917, by PRINCETON UNIVERSITY PRESS Published April, 1917 TO EDWIN G. CONKLIN AND HERBERT S. JENNINGS WHO ENCOURAGED MY EARLY EXPERIMENTATION PREFACE This book comprises a course of lectures and laboratory work given to graduate and advanced medical students in the Uni- versity of Minnesota. The need for special teaching in the ap- plication of the simpler aspects of physical chemistry to biology was first realized by the author while attempting to teach physics and physiology to the same group of college students in 1906. A collection of abstracts of papers on the subject was commenced but interrupted by various affairs, especially the change to med- ical teaching. It became evident, however, that even medical students with a crowded curriculum would do well to devote any available time to this subject if they expect to do any eee or read current medical literature. The purpose of the book is not to go far into physical chem- istry but to develop a tool for physiological research. Lengthy discussions of debated questions are avoided by tentatively ac- cepting the hypothesis which fits the most facts, until a better one appears. For further discussion of any subject the reader is referred to the literature list and index. For facts, however, he is referred to nature. It is not to be hoped that theories should coincide exactly with data available at present. Even in the most exact branches of chemistry the atomic weight deter- minations, for instance, do not exactly coincide with the values calculated from the atomic numbers, and there seems to be some doubt as to whether lead is one element or several. How much more uncertainty there should be about physiology, where de- terminations are vitiated by the great variability of the material and its physiological states. The literature list was compiled from abstracts made in various libraries during the last ten years in addition to published ab- stracts and summaries. In some cases only part of a paper or the summary was read. Following the date is the gist of some data to which it is desired to call attention, or some conclusion which the data apparently justify but which may not be ac- Vi PREFACE cepted by the author of the original paper. The index was made on the basis of these brief notes and hence cannot be relied on to indicate all the papers on a subject that appear in the literature list. The appendix is for the convenience of a limited class of readers. The author expresses his sincere thanks to Professors F. E. Bartell, E. G. Conklin, I. H. Derby, G. A. Hulett, A. F. Kovarik, E. P. Lyon and others for examining the copy or parts of it and offering suggestions, and to Margaret S. McClendon for assist- ance in its revision. J. F. McCLenpon. Minneapolis, October 1, 1916. CONTENTS CHAPTER I THtFOdUCH ON, surarcutet dt Me oven ee ee eae aeee Sones I Definitions of physical properties of aqueous solutions... 12 CHAPTER II Electrolytic Dissociation ........ 0... c ee eee eens ypbateas 17 Osmotic: Pressure sinuses ees oe AMAT S Slee aA eS 29 CHAPTER IV Hydrogen and Hydroxyl Ion Concentration and CO, Pres- SUTG: saie Sioa ene vee Sale Peed gee wee rates oes ae co 36 Determination of hydrogen ion concentration with hydro- gen electrodes: 2.cccatwwde sea ethan pew peewee ons 38 Determination of hydrogen ion concentration by means Of ANdICatOrs, wai acids awed et anus ara We aS wakes 49 Buffers and solutions of standard hydrogen ion concen- TPAHON. Kcgch Ge hed ees ocho eo auig Siew eee eset SI Dissociation constants of acids and bases.............. 54 Dissociation of amphoteric electrolytes (ampholytes).... 57 CHAPTER V Surface Tension and Adsorption............ 0.00.0 cee eee 58 Surface tension of aqueous solutions..:................ 62 AdSOrpllon! ices ea need Cah ER Rene ube aeetelee § 65 ; CHAPTER VI Electrolytes, Non-Electrolytes and Colloids............... 68 Non-electrolytes: iu: tses cw nsec a vane oe auaee one eee 69 Colloids::2 esse. ceri ndanat Gara Gavan Oaee ence wee ead 70 SUSPENSOIdS cowie a Seeded i gawnee, Saw eee eae eee eeR 70 Pemiuls@id$*.ctancai Go uuae ery men enn iuek So om cay narra 73 CHAPTER VII Enzyme Action’ sa:caiies Sareea Mee Ge cha eae Raa eRe 80 CHAPTER VIII Permeability of Cells vos ccwrenee aes ceased eee ean n 88 CHAPTER IX Changes in Permeability of Plant Cells................... 100 Vii Vili CONTENTS CIIAPTER X Negative Osmose and the Polarization of Membranes in Relation to the Bioelectric Phenomena, Stimulation, Absorption and Secretion............:c eee ee cere ees 104 Ne@Sa LIVE: OSINOSE 5 ns waa nk eden ede are Glew tds an Sees 105 Electric polarization of membranes and its relation to OSMOSE savevacsaebe vege sme Hee vdew tea e Os eas Mawes 106 Comparison of the polarization of various types of mem- DRATICS A nncocutn tteie seasons ehiiesttnulg ate aban as on te eee tee 112 Bideleckvie PHENOMENA ose eaieeserows eee esa tweens 118 Stimulation: +.+e-edewsee new ewes a ryaesmaels wor wees 128 The all-orsnone law ...00 doers teceenesre cn eeseaee beeaa ‘130 ADSOFPtOM ITE SECKSCION: geri wile ieiipers) wey abled A areedd son eeeies 130 CHAPTER XI Anésthesia. and NareOsis: susy cscs genet Ga pete eidaoa8 133 CHAPTER XII Cytolysis and Disinfection. s....is0 cdcae rae ey ves weer 142 CHAPTER XIII Ameboid Motion and Tropisms, Cell Division, Fertilization and Parthenogenesis ......... x fata "auc eet ate wal aia acca a atecs 148 Gell division oi.4 sa sean cieelee cenesin a ewe a ong eens ae 156 enti zation sited ho ti nack awe na ate oe canna le eye eae 157 Artiicial parthenogenesis: suc. voce didee ewan ow Je gadve 160 CHAPTER XIV Muscular Contraction, Oxidation and Heat and Light Pro- CUUGELOM Sista: Seton eas Sa in cretetaneneptneeedtea eye aaday a ahaay Sues eaes 164 Striated muscle 2.52. gat Gand awe ee dth ow talretee sea dees 1604 SMOG MUSCIE: bist eye one dere ew erad <6 Wesel ate 166 Omidation: wreueaensebeg oe re se ted She Mey Ox OR a es 166 Heat production: iis sacaeeusa east a teleanee oak ga aks 172 Light production cwisewein caine wad SOAS ede weneaw es 173 CHAPTER XV Blood and Other Cell, Mediaiiuciaewuese sr arsas ee eedaness 175 Sea Water dscsecuv eave ncs via be eecusila ae suse ela phic balers 184 Appendix (Chemical Summary) .......... 00... cee ee eee 188 Abbreviations Used in Literature List................... 194 Diterature: List: co rececabets eareseaaes ox ee aer aa ee ate eds 198 CHAPTER I INTRODUCTION The chemist who turns his attention to biological problems meets at the start a seemingly insurmountable barrier. All living matter being composed of cells, and the surface of the cell in such an unstable condition that it is changed by very mild physical or chemical treatment, the rough treatment necessary for chem- ical analysis is out of the question. This surface layer of the protoplasm has been called by physiologists the plasma mem- brane. If this plasma membrane is destroyed the entire proto- plasm undergoes rapid changes (cytolysis). The protoplasm, therefore, is excluded from the ordinary chemical methods of investigation, the methods that may be applied to the interior of living cells being at present very few, and concerned chiefly with the inorganic constituents. Modern biochemistry is therefore not yet concerned directly with the composition of normal living cells, but with their de- composition products and the exchange between the cell and its surroundings. While the entire cell is treated as a unit and sometimes called protoplasm or the living substance, we have many reasons to believe that it is composed of a large number of different chemical substances, some distributed throughout the cell and others confined to certain regions, some in solution and others in the form of jellies (gels) or solids. The living cell shows a visible structure under the microscope, and chemical differences between parts of the structure may be detected after death of the cell. From our knowledge of the decomposition products of cells and the exchange with the medium, we may speculate on the composition of the cell and the changes that go on in it during functional activity. But before doing this the most exact quanti- tative data on the exchange with the environment are desirable. It is the purpose of this introduction to show that these data 2 PHYSICAL CHEMISTRY cannot be obtained or interpreted without the aid of the methods of physical chemistry. Quantitative chemistry is based on the molecular and atomic theories, and since molecules and atoms obey physical laws, physical chemistry is necessary in order to understand the reactions that take place between them. Though the problems considered in this book are physiological, the methods of attack are chiefly those of the physical chemist. As an illustration of the usefulness of physical chemistry we may consider the grouping of the elements into the periodic sys- tem. Fig. 1 shows the elements grouped according to their physical characters. It may be seen that Li, Na, K, Rb and Cs have corresponding positions in the curves. They also have sim- ilar effects physiologically. Ca, Sr and Ba form another series, whereas Mg stands somewhat apart physiologically as well as physically, and the same is probably true of Be (near B). F, Cl, Br and I form another series (IF, Cl and Br are indicated by spaces homologous with I). It is sometimes supposed that very exact data are not necessary in biochemistry owing to the errors in taking samples and the individual variation of the organisms. We might be interested, for instance, in determining whether dextrose were burned in an animal, but consider the exact rate of oxidation to be of sec- ondary importance. In reality, all qualitative distinctions are based on quantitative differences. When we say that coal does not burn in air at room temperature we mean that the combustion is very slow. Furthermore, the rate of a chemical reaction may determine the possibility of finally detecting the end products. All chemical reactions are theoretically reversible. That is to say, not only does the observed reaction take place, but the op- posite reaction is taking place at the same time at a slower rate. The most rapid reactions occur between electrically charged atoms or complexes called ions. Positive ions, called cations, are attracted to and combine with negatively charged ions, anions. If we mix an acid (containing H ions) with a base (containing OH ions) the H’ and OH’ combine to form H,O. But the re- verse reaction also takes place. Water dissociates into H and OH ions, but their number is so small that in all ordinary chem- ical work they are never detected. The reason for this lies in the difference in speed of the two reactions. The combination “(S161 ‘spre “AA. oes - TY ML ‘SOV wosz) woisks sporsad ayy, ‘1 ‘ong siysiaa, Swoop O01 4 PELY SICAL: CHEMISTRY takes place with enormous rapidity and with the evolution of heat, whereas the dissociation takes place slowly. As soon as a molecule of water dissociates, its ions recombine to form water. This combination takes place whenever a hydrogen ion meets a hydroxyl ion. Hence, the speed of this reaction obeys physical laws. Since ions of opposite charge combine when they meet, the speed of the reaction depends on the rapidity of movement of the ions and their number in unit volume, or concentration. Since the ionic speed of the same ion at constant temperature and viscosity of the solution is constant, the rate of reaction depends on the concentration. This is called the law of mass action, The behavior of the ions may be compared to men and women in a cotillion. Each man has a chance of meeting each woman, Similarly, each cation has a chance of meeting each anion, and the number of chances of a cation meeting an anion is the number of cations multiplied by the number of anions, in unit volume. Since the concentration of the reacting substances changes during the reaction, the rate of reaction changes, and is usually negatively accelerated. The mathematical process by which the rate at any particular moment is determined is called differentia- tion (differential calculus). The rate is determined by the amount of substance transformed, divided by the time. If the rate were uniform we could find it by dividing the difference in the amount of substance at the beginning and end of an ob- servation period, by the difference in time at the beginning and end of the period. But in an accelerated reaction the rate is changing from moment to moment, and the rate at any particular dx time is expressed by the differential, a Since the rate cannot dt be measured in a moment, it is necessary to use the differential calculus in order to estimate it. For our purposes, however, it is not necessary to go through all of the mathematical reasoning, but merely to use the formula supplied by the mathematician, which varies according to the conditions of the reaction. In actual practice, ionic reactions are usually too rapid to be measured. Even the point of equilibrium may sometimes be so OF VITAL PHENOMENA 5 near one end as to be ascertained with difficulty. The above reactions were given as an example because their nature seems to be better understood. The reactions whose rate can be easily measured are usually splittings and combinations of molecules. Many of these have been found to obey the laws of mass ac- tion. A monomolecular reaction in unit volume is expressed: dx . = c(a—x), where a is the original amount of substance, 4 is t the amount transformed in the time ¢, and c is the constant of the reaction that it is desired to find. From the calculus we In this equation log, signifies the obtain: c = — log, t a—x natural logarithm (to the base e = 2.71828), but this may be reduced to the common logarithm (to the base 10), abbreviated, A or log. Since log,, = log, X .4343, the above formula be- I comes: c = — .4343 logy, When several kinds of mole- t cules are concerned the formulae become much more complicated, but in biochemistry we are less often concerned with the rate of reaction than with the point of equilibrium of a reversible reaction. This equilibrium point in a reversible reaction is illustrated in the case of H,O. The H,O dissociates into H’ and OH’ and these recombine to form H,O. This is in one direction a bimolecular (bi-ionic) reaction, and in the reverse direction a monomolecular reaction. But this latter, the dissociation of H,O, may be disregarded mathematically because the concentra- tion of the H,O (at constant temperature) does not measurably change. At the equilibrium point [H’]xX{OH’] = a constant, where [] denotes the concentration of what follows. At 22°, [H*]x[OH’] = t1o-* and therefore if we increase the concen- tration of H’ by adding acid the concentration of OH’ is de- creased, and vice versa. In pure water [H’] or [OH’] = 107 at 22° and any variation from this is acid or alkaline. We may measure acidity or alkalinity either by estimating the concentra- tion of the H’ or OH’, but the hydrogen ions are the ones usually estimated, as will be described in a succeeding chapter. In any neutral dilute aqueous solution the concentration of the 6 - PHYSICAL CHEMISTRY hydrogen and hydroxyl ions is nearly the same as in pure water. A nearly neutral reaction is very necessary to the life of proto- plasm. The fluids that bathe the majority of body cells, and the waters in which aquatic organisms live are very nearly neutral in reaction, and are maintained in this condition by the presence of carbonates and phosphates (buffers), as will be described later. The decomposition products of cells are proteins, carbohydrates, fats and fatlike bodies and neutral salts, as well as other sub- stances that occur in small amount or which may arise from the decomposition of the above. The proteins are composed of amino acids. Amino acids have the general formula NH,.... COOH, in which the COOH group has acid and the NH, group (after hydration) has alkaline properties, so that the amino acid may be nearly neutral. The proteins are formed by the union of the COOH group of one amino acid with the NH, group of another with the elimination of one molecule of water. The number of amino acid molecules in one molecule of protein is very large and hence the molecular weight of proteins is enor- mous and is not very definitely settled in many cases. Before the proteins of the food are taken into the cells they are broken down into amino acids. Each cell builds up its characteristic proteins, irrespective of the proteins given as food. The carbohydrates are aldehydes or ketones of polyhydric alcohols. Because of their aldehyde character, they are more easily burned in the body, and furnish most of the energy for muscular work. Some of them undergo a molecular rearrange- ment, giving rise to the lactone form without free aldehyde or ketone groups, but these lactone forms are changed back to the original type in digestion or metabolism. The carbohydrates are stored in insoluble form, and transported in soluble form (sugar). The fats are esters (salts) of glycerine or other polyhydric alcohols, and fatty acids. The fats in adipose tissue are saturated and are insoluble in water. The fats of other cells are to a large extent unsaturated, and many of them contain a choline and phosphoric acid radical, which makes them capable of forming a colloidal solution with water. These phosphorized fats are perhaps more correctly called phospholipines, but together with cholesterine (a polyhydric alcohol) they have been called lipoids by many physiologists. OF VITAL PHENOMENA 7 The burning of 1 g monosaccharide yields 3.74 large calories, disaccharide 3.95, animal or vegetable fat 9.5, animal protein 5.7. All of this heat is produced by their burning in the body, except in case of protein, which produces only 4.5 calories as it is not completely burned, being eliminated as urea and uric acid and ammonia, etc. The mineral constituents are apparently for the most part dis- solved in the water contained in the cell and will be considered later in regard to their effect on the solubilities (aggregation states) of the proteins and phospholipines. Among those constituents occurring only in traces the most important are the enzymes, thermolabile substances of unknown composition which accelerate certain chemical reactions. Some of the enzymes are poured out of the cells (as pepsin, for in- stance) so that they may be easily obtained, but many enzymes that are supposed to exist in all cells have been looked for in vain. Such are the enzymes that are supposed to accelerate the oxidation of the foodstuffs. It now appears that such oxidations are inseparably connected with the cell structure or to some sub- stance that is destroyed when the cell structure is destroyed. The enzymes are greatly influenced in their activity by the hydrogen ion concentration. They may be rendered inactive by adsorption, or by anesthetics and they are influenced to some extent by neu- tral salts. Most of the constituents of cells are called colloids on account of their physical properties. Colloids are divided into two classes, suspensoids and emulsoids. Suspensoids are merely solid particles electrically charged and suspended in water, only distinguished from suspensions by the small size of the particles, which cannot usually be seen with the ordinary microscope but only with the ultramicroscope with a powerful dark ground illumination. The suspensoids are precipitated by small quantities of neutral salts or other electrolytes (substances which dissociate into ions), because ions of opposite charge to the particles collide with them and neutralize their charge, the particles gravitating, no longer having the electric charges to hold them up. Emulsoids are very different in some ways. The colloidal par- ticles partly dissolve. The remainder absorbs water and swells, becoming viscid and the result is an ultramicroscopic emulsion 8 PHYSICAL CHEMISTRY of this viscous fluid. When two substances or fluids do not mix homogeneously they are called phases. In the suspensoid solu- tion one phase is the solid particles and the other the water. In the emulsoid solution both phases contain water and colloid, but one is very rich in water and the other is relatively poor in water. Emulsoids may be precipitated with large quantities of salts in the same way that alcohol may be salted out of water, but they are not affected by the small amount of salt necessary to precipitate suspensoids. The particles of typical emulsoids cannot always be seen with the ultramicroscope, but the particles of lecithin, a phospholipine, for instance, are usually distinct. Many protein solutions which are typical emulsoids are trans- formed into stspensoids by boiling. This change, which is called denaturation, is caused by many substances, which are therefore used in tests for proteins. Emulsoids increase the viscosity and decrease the surface tension of water, whereas suspensoids do not. Since all substances that reduce surface tension become more concentrated in the surface film, the same is true of the emulsoids. The emulsoid in the surface film gradually changes into an elastic membrane, a so-called haptogen membrane. ‘Colloids have the peculiar property of forming jellies, called gels to distinguish them from their solutions called sols. The gel formed by a suspensoid consists of a spongelike structure formed of rows of colloidal particles. No structure can be seen in the gels of some emulsoids, but there is evidence for such a structure in their elasticity. An emulsoid increases the viscosity of water. The greater the concentration of the emulsoid the greater the viscosity, until very concentrated solutions have the viscosity of jelly, and are therefore gels. The viscosity of emulsoid sols and gels is not entirely dependent on concentration but is influenced by temperature and the presence of dissolved substances. Whereas we may learn a great deal about the exchange be- tween the cells and the exterior by studying the intake and out- put of the lungs, the products of digestion that are absorbed by the alimentary canal and the output of the kidneys, many cells are so far removed from these organs that much is left to be learned about their exchange. These cells are bathed by tissue juice, which is probably somewhat similar to the blood plasma. OF VITAL PHENOMENA 9 In fact, the blood plasma itself comes in contact with some of the cells. The blood plasma contains amino acids, sugar and fats for the nourishment of the cells. The neutral salts in the plasma main- tain the proper viscosity of the emulsoids, especially those of the plasma membranes of the cells. The carbonates, phosphates and to a small extent the proteins maintain the nearly neutral reaction of the plasma. The chief function of the serum albumin and globulin is not known; these proteins increase the viscosity of the blood and throw more work on the heart in maintaining the circulation. They are probably not absorbed by the cells because they appear to be different from the cell proteins. They prob- ably exert a protective action on the plasma membranes of the cells and increase the solubility of certain substances, such as uric acid, by holding them in colloidal solution. Many inter- mediate products of metabolism and waste products are carried from certain cells to certain others by the blood. The presence of hormones in the blood, which stimulate certain organs to activ- ity, seems to be established, but the chemistry of these substances, with the exception of adrenalin, is unknown. The plasma also contains the substances that form the fibrin of blood clots, and many enzymes whose function is not very clear. The exchange between the cells and the fluid bathing them is caused by diffusion of dissolved substances, but if this were unlimited the dissolved substances of all of the cells would be the same, which is not the case. Diffusion is fairly rapid through water but decreases as the viscosity increases. The increase of viscosity due to emulsoids does not appear to explain entirely the limitation of the diffusion of some substances, and the prob- lem has never quite been solved, though many models showing how it might occur have been borrowed from pure chemistry. Traube’s membranes form one series of models. If a solution of potassium ferrocyanide is brought in contact with a solution of a copper salt, a film of copper ferrocyanide is formed at the plane of contact of the two liquids. This film is easily permeable to water but impermeable to potassium ferrocyanide, copper salts and many other substances, such as sugar. The permeability of this membrane may be increased by treating it with certain solutions without destroying its mechanical continuity. During 10 PHYSICAL CHEMISTRY this process the membrane seems to change from a colloid struc- ture to a mass of microscopic crystals. ‘We do not know the nature of the plasma membrane, but the normal cell is impermeable, or very poorly permeable, to certain salts and some other substances. Some fish eggs are impermeable to salts and to water. The permeability of cells is increased on stimulation, and goes back to normal during rest. All cells are permeable to a host of substances that reduce the surface tension of water to a marked degree, and to many substances that dis- solve in certain non-aqueous media, although some substances that do not reduce the surface tension of water or dissolve in these media penetrate cells. If any solution is separated from pure water or a less concen- trated solution by a membrane to which the dissolved substance (solute) is impermeable, the solute exerts pressure on the mem- brane, and the water passes through the membrane into the solu- tion. This pressure is called osmotic pressure, and depends not on the percentage of solute, but on the number of molecules and ions per unit volume. The standard concentration is the molecular weight of a substance in grams dissolved in a liter of water. This exerts an osmotic pressure of 22.4 atmospheres and is called a mol. If the molecules partly dissociate into ions the osmotic pressure is increased. The osmotic pressure is difficult to meas- ure directly because it is difficult to obtain membranes that can stand the pressure. Since it has been found that the osmotic pressure is proportional to the lowering of the freezing point of pure water due to adding the dissolved substance, the freezing point is usually determined and the osmotic pressure calculated. When the osmotic pressure is greater on the inside than on the outside of a cell, the cell expands unless the cell wall is strong enough to stand the full pressure without stretching. In green plants the osmotic pressure is greater on the inside than in the water bathing the roots, because the dissolved substances are mostly manufactured on the inside. Plants use osmotic pressure as the force for growth, and can force asunder great rocks when they grow in a crack between them. The osmotic pressure of the blood of mammals is almost as constant as the body tempera- ture, but we do not thoroughly understand its role in physiology. When an organ works, large molecules are broken down into OF VITAL PHENOMENA I small ones, the number of molecules and the osmotic pressure are increased and water is drawn out of the blood. But when the organ rests, or grows, and large molecules are formed of small ones, the reverse process does not occur. At least the water does not flow in the opposite direction. The water that was drawn out of the blood in the first instance finally passes into the lymph vessels and then back into the blood, causing an increased flow of lymph, but the lymph flow never changes in direction. The restricted permeability (called semipermeability) of the plasma membrane of muscle and nerve cells gives the clue for understanding the electric phenomena of these tissues. The rest- ing plasma membrane seems to be permeable to some cations but impermeable to all anions. The cations of some substances that are more concentrated within the cell than outside diffuse through the plasma membrane, but they cannot go far, being held back by the attraction of the opposite electric charge of the anions. These cations on the outer surface of the plasma membrane give the whole cell surface a positive charge. If the plasma membrane is stimulated at one point, this altered region becomes. permeable to anions and therefore negative in comparison with the unaltered portion. If the altered and unaltered portions are connected by means of a wire, a current flows through the wire from the un- altered to the altered region. This electric current is called the action current or the current of injury, according to whether it is caused by stimulation or injury of the plasma membrane. Such bioelectric currents are very strong in the electric organs of certain fish, are also noticeable in the sensitive plants and in glands, and perhaps occur generally. Since the body is made up of numerous cells and each cell is composed of several phases, the surface phenomena are very important. While the interiors of solutions are homogeneous, the surface film has peculiar properties, due to the strained rela- tions of the molecules. Dissolved substances (solutes) that re- duce the surface tension of the solvent tend to become more concentrated in the surface film, whereas solutes that increase the surface tension are less concentrated in the surface film. If a solute that decreases the surface tension of one phase, becom- ing more concentrated in its surface film, is soluble in the second phase, it diffuses into the second phase (is absorbed by it); but 12 PHYSICAL CHEMISTRY if it is insoluble in the second phase it remains concentrated in the phase boundary, and is said to be adsorbed by the second phase. Electric polarization, such as was described above in regard to nerve and muscle, decreases the surface tension. Hence stimulation is followed by local increase in surface tension. Surface tension changes cause ameboid movements and cell division. Some suppose that muscular contraction is due to surface tension ‘changes, but if this is the case the surfaces con- cerned must be those of colloidal particles or internal structures, as the surface of the muscle fiber is not large enough to account for the force of ‘contraction. We thus see that a knowledge of what is ordinarily called chemistry is not sufficient for the biochemist dealing with med- ical or biological problems. Beside the reactions between pro- teins, carbohydrates, fats, and many organic and inorganic compounds as usually considered by the biochemist, we are concerned with such physico-chemical processes as the rate of reaction and the position of equilibrium as expressed in the law of mass action, with the effect of ions, especially H’ and OH’, osmotic pressure, phase boundaries and the surface tension, dif- fusion, adsorption ‘and electrical polarization phenomena that occur at the phase boundaries, with colloids and their aggrega- tion states, whether gels or sols, with the effect of salts on these colloids, and especially on the plasma membrane which is ap- parently a colloidal structure, with the enzymes and their colloidal state and dissociation, and finally with certain reactions that are apparently accelerated by cell structure, presumably through the intermediation of adsorption phenomena. Definitions of Physical Properties of Aqueous Solutions There is a group of properties of water which are affected pro- portionately by the introduction of a solute. These are called by Washburn, 1915, the colligative properties of the solution. If the solution is sufficiently dilute, the effect of the solute on its colligative properties is independent of the chemical nature of the solute, and determined solely by the number of dissolved particles (molecules + ions). The colligative properties are: 1—Vapor Pressure. If water is introduced into a vacuum OF VITAL PHENOMENA 13 it will evaporate until the pressure of the vapor reaches a certain value, dependent on the temperature. The vapor pressure of pure water at 20° is 17.4 mm, at 25° 23.5 mm, at 30° 31.6 mm, and at 37° 46.7 mm. The lowering of the vapor pressure by 1 mol solute at body temperature is only about .5 mm and is less at room temperature since it is a relative lowering and the vapor pressure of pure water is less at lower temperature. 2—Boiling Point. The boiling point of water is raised .54° by 1 mol solute. (Vol. = 1 liter where not stated.) 3—Freezing Point. The freezing point is lowered 1.85° by I mol solute. 4—Osmotic Pressure. If a mol solution is enclosed in a vessel whose walls are impermeable to the solute and permeable to the water, and immersed in pure water, water will pass into the vessel, causing a pressure, osmotic pressure, of 22.4 atmos- pheres. With these colligative properties might be classed electrode potentials, since they depend on osmotic pressure. The concen- tration of a solute calculated from its effect on all colligative properties is the same, but may differ from its concentration cal- culated from other data, so the word activity is sometimes used to denote concentration calculated from colligative data. The density of the solution is affected by the concentration of the solute, but the degree of change differs with different solutes. Hence, this property of a mixed solution cannot be interpreted un- less the proportion of the different solutes remains approximately the same (as in sea water, for instance). Density is determined by weighing a certain volume of the solution measured in a pycnome- ter and dividing its weight by the weight of an equal volume of water. The rule has been to have the water at 4° and the solu- tion at 15°, but in many determinations the water is taken at the same temperature as the solution, and 25° is rapidly becoming the standard temperature for all sorts of measurements. The refractive index is also used to determine concentration. With the Abbe direct reading refractometer only a drop of the solution is necessary, and thence this instrument is used in protein analysis when the protein is pure or the accompanying solutes are known. The Zeiss interferometer gives a more accurate 14 PHYSICAL CHEMISTRY reading but requires a larger sample. One per cent of protein raises the refractive index .oo1 per cent. The viscosity of the solution is affected very little by neutral salts out very much by emulsion colloids. Not only does the concentration of the emulsoid change the viscosity, but (at the same concentration) the colloidal state affects it. Apparently, the greater the hydration of the colloid the greater the viscosity. The viscosity of a solution is measured by the time required for it to flow through a capillary tube divided by the time required by pure water to flow through the tube at the same temperature. The rotation of the plane of polarized light may be used to find the concentration of an asymmetric solute in a mixed solu- tion since only molecules having an asymmetric atom, usually carbon, have this property. Rotation is measured with a polari- meter. Colloidal solutions may polarize light dispersed by the particles (Tyndall effect) and gels polarize light when deformed, and are then called doubly refractive or anisotropic. The surface tension may be used as an index of the concentra- tion of certain solutes. Neutral inorganic salts have very iittle effect on the surface tension, but anesthetics have a marked effect. The surface tension is found by dividing the weight of a drop of the solution by the weight of a drop of water dropped from the same pipette. The electrical conductivity is much used to find the concentra- tion of ions, but it depends, not only on the number, but also on the speed of the ions, and hence on the viscosity of the solu- tion. The greater the hydration of an ion the less is its speed, hence the speed is supposed by some writers to decrease with decrease in concentration until maximal hydration occurs. When such a dilution is reached, further dilution evolves no heat, and the solution is called “dilute.” The color of a solution is determined qualitatively with the spectroscope and quantitatively with the colorimeter. A change in the quality of the color is supposed by Stieglitz to be due to change in the positions of electrons within the molecule, follow- ing an upsetting of the equilibrium by addition or removal of atomic groups. It seems probable that a change in the degree of hydration may lead to a change in color. The color of a sol may be due to the size and refractivity of the colloid particles, OF VITAL PHENOMENA 15 The degree of turbidity of a sol or suspension is determined with Richards’s nephelometer. In order to facilitate comparison of the results of different investigators, the standards used in measurement should always be recorded. The practice of measuring dimensions in the metric system and temperature in degrees centigrade (Celsius) is quite general, but some confusion may arise from any assumptions as to the concentration of solutions. The effect of the acceleration of gravity may be neglected in weighing, because it affects equally the weights used and the substance weighed. The buoyancy of the air is taken into consideration in the finest work and especially for very light substances. Certificates of the U. S. Bureau of Standards give weights in vacuo, hence the volume of the weights must be subtracted from the volume of the substance weighed in correcting for the buoyancy of the air. The lengths of the two arms of the balance beam are often sufficiently different to produce an appreciable error in weighing. By determining the ratio of the lengths of the two arms a cor- rection may be applied. Or the true weight may be found by taking the geometric mean of the weights on the two pans (after a second weighing on the opposite pan). The standard solution or m, is the gram-molecular-weight of the solute in a liter of the solution, but the liter flask from the Bureau of Standards should be used at the temperature for which it was standardized. After the solution is standardized, any change in temperature changes its volume and hence burettes and pipettes must be used at the same temperature as the flask. A flask standardized at 15° would hold 0.4 cc too much at 30°, but if it is merely a question of volumetric analysis, this can easily be corrected for as the pipettes and burettes likewise hold 0.04 per cent too much. If a liter flask is standardized at 15° it holds about 998 g H,O at 15°, 996.3 at 25° and 995 at 30° when weighed in air. This refers to the true liter (the volume of a kilogram of H,O at 4°) and not to the Mohr liter. ‘A liter meas- ures 1000.027 cc but in this book cc is used to indicate 0.001 liter or milli-liter (ml). It is often desirable to use solutions under various conditions, and since their concentration according to the above definition may change, new definitions are substituted. Since the molecular 16 PHYSICAL CHEMISTRY weight of a substance may change upon solution, the weight in grams as given in the chemical formula (mol) is usually taken, and the solution of this in a liter is called formal but is designated here as mol in order to save space. When attention is especially directed to an element that occurs more than once in the formula, the molecular weight is divided by the number of times this sub- stance occurs in the molecule (= gram equivalent weight), and the solution of this in 1 liter is then called normal. The effects of temperature are eliminated by using weight normal solutions, in which the formal or normal (gram equivalent) weight of the substance is dissolved in 1000 grams of the solvent, but such solutions require a new standardization before use in burettes. The requirements of volumetric analysis are satisfied in the method used in titrating the chloride content of sea water. The results are expressed as grams of Cl per kilogram of sea water. The volumetric apparatus is standardized with a bottle of stand- ard sea water at the temperature at which the titrations are to be made. It is then necessary merely to have a relative calibra- tion of the divisions on the burette. CHAPTER II ELECTROLYTIC DISSOCIATION Electrolytic dissociation is not dependent on electrolysis as was formerly supposed. When certain substances are dissolved in water they dissociate into electrically charged ions, and these substances are therefore called electrolytes, to distinguish them from poorly dissociated, so-called non-electrolytes, such as sugar or urea. The individual ions in gases may be detected, but in solutions we are usually content with the circumstantial evidence of their existence. In biology we usually have to deal with aqueous solutions, and these are implied where others are not stated. Electrolytes that dissociate to a great extent in water dissociate much less if at all in many non-aqueous solutions. Strong acids and bases and their salts are almost completely dissociated in very dilute solutions, the dissociation increasing with dilution. Weak acids and bases and their salts are as a rule poorly dissociated, but salts formed of a weak acid and a strong base or a weak base and a strong acid are more strongly disso- ciated. As a rule, inorganic acids and bases are strong and organic weak, but there are exceptions. Solutions of all chlorides (NaCl, KCl, LiCl, CaCl, ...) con- tain chlorine ions, NaCl dissociating into positively charged Na ions (Na’) and negatively charged Cl ions (Cl’). These ions are never free as represented but always hydrated. Silver nitrate in solution dissociates into Ag’ and NO,’. If silver nitrate is added to the solution of any chloride a white cloud of AgCl is instantly formed because Ag” unites with Cl’, the two being drawn together by their electric charges. Hydrated cobalt ions give a pink color to their solution, but the undissociated salts (and possibly non-hydrated ions if they exist) are of different colors, as may be seen by dissolving them in solvents in which they do not ionize. Cobalt chlorid in alcohol is blue, but if water is added the solution turns pink. ‘Cobalt 18 PHYSICAL CHEMISTRY nitrate in alcohol is purple, but on adding water it turns pink, because in the water-alcohol mixture electrolytic dissociation takes place (Noyes and Blanchard, 1900). Electric conductivity of solutions: Solutions of electrolytes conduct the electric current and are called conductors of the second class to distinguish them from the metals which are con- ductors of the first class. If an electric current is passed through a solution from two metallic conductors (electrodes) the positive ions (cations) are attracted to the negative electrode (cathode) and the negative ions (anions) are attracted to the positive electrode (anode). The more ions there are in a solution the greater the electric conductivity, and hence the electric conductivity may be used to determine the ionization. In doing this the electrical resistance, in ohms, is measured, and the conductivity is the reciprocal of the resistance. The electrical resistance of solutions is measured by means of the Kohlrausch method. The solution to be examined is placed in a conductivity cell which consists of a glass vessel containing two platinum electrodes. The electrodes are made of platinum foil and should stand vertically so that bubbles will not collect on them. Every time the distance between the electrodes is changed to the slightest degree the cell has to be standardized again. To avoid this, the platinum is often made thick for stiff- ness, or the four corners of one electrode are connected to the corners of the other by means of glass rods fused to the platinum by heat. To the upper edge of the platinum foil a stout platinum wire is welded. This is done by heating foil and wire to a white heat and welding the wire to the foil by means of a quick tap with a hammer. The wire is fused into the end of a small glass tube and a drop of mercury dropped into the tube so as to touch the platinum wire. When connecting up the apparatus, a copper wire is inserted down the tube into the mercury. The electrodes may be fastened into the cell by passing the glass tubes through a stopper that fits into the cell. For solutions used in pure chemistry the pipette forms of con- ductivity cells that are on the market are very convenient. For biological fluids when only a small quantity may be obtained, the test tube form of cell shown in Fig. 2 is convenient. For tissues, the apparatus shown in Fig. 3 is useful. OF VITAL PHENOMENA 19 Fic. 2. Electric conductivity electrode of low inductive capacity. Before using the cell, it must be cleaned with a saturated solu- tion of potassium bichromate in concentrated sulphuric acid (called cleaning fluid). The platinum should be cleaned by heat before fusing in the glass, and cleaned with cleaning fluid in the cell. The cell is rinsed with distilled water and the platinum is coated with platinum black (platinized) in order to increase its Chm] jf Th] i Fic, 3. Electric conductivity electrode for tissues. 20 PHYSICAL CHEMISTRY surface and reduce electric polarization. In doing this the cell is filled with about 2 per cent platinic chloride solution containing a trace of basic lead acetate. An electric current of about four volts is passed through the cell until one electrode is blackened and the current is reversed until the other pole is blackened. The plati- nizing solution is returned to the bottle and the cell rinsed and filled with dilute sulphuric acid. A current is now passed in both directions as before. In this way hydrogen is produced, first on one electrode and then on the other, and reduces any chlorine that may have been absorbed by the platinum. The cell is now rinsed many times, finally with conductivity water, is filled with the latter and left until used. Conductivity water is made by adding sulphuric acid and potassium bichromate to distilled water and redistilling it, then adding barium hydrate to it and distilling it the third time with the exclusion of CO, of the air. Both distillations may be done at once (Jones, Hulett). In order to reduce polarization still further, a rapidly alter- nating current is used. This is best obtained from a special electric generator, or Vreeland oscillator, but owing to its cost most people are content with a small induction coil. The vibrator of the coil should be very stiff or very short, in order to produce a high pitch resembling the sound of a mosquito. A great change in the frequency may change the resistance measured 3 per cent (W. A. Taylor, 1915). The coil should be enclosed in a sound proof box. A Wheatstone bridge is built up of a resistance box, the con- Fic. 4. Wheatstone bridge arrangement for conductivity apparatus. OF VITAL PHENOMENA 21 ductivity vessel, a meter resistance wire with a sliding contact, and a telephone with which to detect the current (Fig. 4). These resistances are connected in a circle. The meter wire is divided by the sliding contact into two resistances which form two legs of the circuit, the box and the cell forming the other two legs. The two secondary poles of the induction coil are connected to the sliding contact and the juncture between coil and box re- spectively. The conductivity cell is marked A and the adjacent leg of the slide wire B, the box marked C and the adjacent leg of the slide wire D. The current entering the circuit at the juncture of A and C divides, part going through A and B and the other part through C and D. If the two ends of the meter wire have the same electrical potential, then the resistances of A C A B — = —, also — = —. In order to determine whether the two B D C D ends of the meter wire have the same potential the two wires of the telephone receiver are connected to the two ends and if no sound is heard the two ends have the same potential. If a sound is heard the resistance of the box is changed or the sliding con- tact on the wire is moved until no sound is heard. The resistance of the box may be read in ohms; the resistances of the two parts of the meter wire are proportional to their length, and hence their lengths are used in the equation. From the equation the resistance of the conductivity cell A may be calculated. The ratio B/D may be read from the accompanying table. Usually the telephone is never quite silent, and the point of tone minimum may be more or less sharp, but may be sharpened in the following ways. The electrodes are made larger (their surface area increased). A self inductance, which may be varied, is placed in series with A. An electrical condenser, that may be varied, is placed in parallel with C. By readjusting the in- ductance and condenser and the sliding contact alternately, a sharp tone minimum is finally obtained (Washburn and Bell, 1913). The condenser is to compensate for the capacity of the cell, which is larger the larger and closer together the electrodes are (but is least in the form of cell shown in Fig. 2). The self inductance is to compensate for the self inductance of the box and connecting wires. Resistance coils with very low self in- 22 PHYSICAL CHEMISTRY Oxsacn’s WHEATSTONE Bripce Taste or B/D Wuere B = Meter SLIDE FROM 0 TO SLipinc Contact AND D = REMAINDER OF SLIDE WIRE. 400] 410} 420] 430} 440] 450] 460] 470] 480] 490 .6667 | .6949 | .7241 | .7544 | .7857 | 8182 | 8519 | .8868 | -9231 | .9608 6694 | .6978 | .7271 | .7575 | .7889 | 8215 | .8553 | 8904 | -9268 | .9646 6722 | .7007 | .7301 | .7606 | .7921 | .8248 | .8587 | .8939 | -9305 | .9685 6750 | .7036 | .7331 | .7637 | .7952 | .8282 | .8622 | .8975 | -9342 | .9724 6779 | .7065 | .7361 | .7668 | .7996 | 8315 | 8657 | .gorr | -9380 | .9763 6807 | .7094 | .7391 | .7699 | 8018 | .8314 | 8692 | .9048 | .9417 | .9812 6835 | .7123 | .7422 | .7731 | 8051 | .8382 | 8727 | .9084 | .9455 | .9841 6863 | .7153 | .7452 | .7762 | .8083 | .8416 | 8762 | .9120 | .9493 | .9881 6892 | .7182 | .7483 | .7794 | .8116 | .8450 | .8797 | .9157 | -9531 | .9920 .6921 | .7212 | .7513, | .7825 | 8149 | 8484 | .8832 | .9194 | .9569 | .9966 the table following, 1 is understood before the decimal point. 500 | 510] 520] 530] S40} 550] 560] 570] 580] 590 .0000 | .0408 | .0833 | .1277 | .1739 | .2222 | .2727 | .3256 | .3810 | .4390 20040 | .0450 | .0877 | .1322 | .1786 | .2272 | .2779 | .3310 | .3866 | .4450 .0080 | .0499 | .0921 | .1368 | .1834 | .2321 | .2831 | .3364 | .3923 | .4510 0121 | .0534 | .0964 | .1413 | .1882 | .2371 | .2883 | .3319 | .3981 | .4570 0161 | .0576 | .1008 | .1459 | .1930 | .2422 | .2936 | .3474 | .4038 | .4631 0202 | .o619 | .1053 | .1505 | .1978 | .2472 | .2989 | .3529 | .4096 | .4691 .0243 | .0661 | .1097 | .1552 | .2026 | .2523 | .3041 | .3585 | .4155 | .4752 .0284 | .0704 | .1142 | .1598 | .2075 | .2573 | .3095 | .3641 | .4213 | .4814 .0325 | .0747 | .1186 | .1645 | .2124 | .2624 | .3148 | .3697 | .4272 | .4876 .0367 | .0790 | .1231 | .1692 | .2173 | .2676 | .3202 | .3753 | -4331 | .4938 Coronrunno | ty iy wor onsunno | ty 5 ductance may be made by bifilar winding or lateral compression of the coil into one plane. A sharp tone minimum may be ob- tained and the telephone not be sensitive enough to detect it. A telephone that is tuned to the pitch of the induction coil is better, but the tune of the coil may change even though the spring of the vibrator is very stiff. A high frequency generator or Vree- land oscillator should not change in pitch, and is necessary for the greatest accuracy. Since 1° rise in temperature causes an increase in electric con- ductivity of about 2.5 per cent, the conductivity cell must be placed in a water bath whose temperature is kept constant or observed very accurately at the moment of the determination. If the electrodes are 1 cm apart and have I sq. cm surface the conductivity of the solution in reciprocal ohms is the specific conductivity. The specific conductivity divided by the concentra- - tion (#7) is called the molecular conductivity (A). The usual OF VITAL PHENOMENA 23 practice is not to measure the electrodes but to calibrate the cell with a known solution of KCI. It is found that the molecular conductivity of an electrolyte increases with dilution, or, in other words, the dissociation in- creases. At infinite dilution the dissociation would be complete, and is practically complete at .coo1 mol. The question may be asked: Where does the electric charge of the ion come from? The study of radium has shown that the molecule contains a store of electricity but the positive charges exactly equal the negative charges and the molecule therefore is electrically neutral. These charges may exist free from molecules or ions and are then called electrons. It seems probable that negative electrons have no weight. A molecule of NaCl may be represented by an atom of Na and an atom of C1, each with a positive charge, connected by means of two negative electrons. When the molecule dissociates the negative electrons go with the Cl atom and give it an excess of one negative charge, whereas the Na atom has a positive charge. If an electric current is passed through a solution, anions are deposited on the anode and cations on the cathode. It is neces- sary to pass 96500 coulombs of electricity (= 1 Faraday) in order to deposit 1 gram equivalent of ions on an electrode. If the ions remain on the electrodes as in electroplating, a gram molecule of the electrolyte is removed from the solution by the passage of 96500 coulombs, for a gram equivalent of anions is deposited on the anode and a gram equivalent of cations on the cathode. In any cross section of the solution, if x gram equiva- lents of anions is moving in one direction, I—x gram equiva- lents of cations is moving in the opposite direction. Supposing that the cations move twice as fast as the anions, if we draw an imaginary cross section half, way between the electrodes, twice as many cations will pass going in one direction as anions going in the opposite direction, or 24 gram equivalent of cations move to the cathode and % gram equivalent of anions to the anode. Around the cathode 1 gram equivalent of cations is removed by the electrode and % is gained by migration, leaving a deficiency of 4%, whereas % of anions are lost by migration, or, in other words, %4 mol electrolyte is lost. At the anode % mol electrolyte is lost. The change in concentration of the electrolyte at the 24 PHYSICAL CHEMISTRY electrode gives the transport number of the ion. By following the above reasoning backward, the ionic speed may be calculated (Hittorf). These values of ionic speed are relative. The actual speed of ions is slow, as is shown by electrolyzing a solution containing colored anions around the cathode, and observing the time neces- sary for them to reach the anode. The relative speeds of ions may be more conveniently deter- mined by comparing the molecular conductivities of a series of salts that are completely dissociated. The molecular conductivity of a salt is proportional to the sum of the ionic speeds of anion and cation (v-+u). Thus, the ratio of the molecular conductiv- ities of NaCl and KCl is the ratio of the ionic speeds of Na and K. The relative ionic speeds at 18° according to Kohlrausch (1907) are as follows: H 318. OH 174. With organic ions, the longer Li 33.4 F 40.6 the carbon chain the less the Na 43.5 (Cl 65.5 speed (Bredig, 1894). K 64.6 Br 67. HCOO 54.5 at 25° Rb 67.5 I 66.5 ‘CH,COO 40.8 Cs 68. NO, 61.7 CsH,COO 36.5 NH, 64.4 CNS 56.6 C;H,COO 32.7 Ag 54.3 ‘C10, 55 C,HgCOO 30.7 a Ba 55 SO, 68 C35H.,COO 29.2 4 Sr sr YC.O, 63 Ca 51 Y%Mg 45 In general we may divide electrolytes into two classes, the strong and the weak. Strong electrolytes are greatly dissociated, whereas weak electrolytes are poorly dissociated. So-called non- electrolytes may be to a minute extent dissociated. Water is a non-electrolyte; its ions are the most rapid, but it is poorly dissociated. Whereas the concentration of water is about 55 formal (55 x 18 g per liter), only 10-7 mol is dissociated at 22°. {Owing to the partial association of H,O into (H,O,) its con- centration is less than 55 mol.] Strong electrolytes have not yet been brought entirely under the law of mass action. Weak electrolytes obey the law, and therefore their ions must obey it. Take, for example, the disso- ciation of acetic acid at different dilutions. The equation for OF VITAL PHENOMENA 25 this sort of phenomenon was found even before the law of mass action was so widely applied, and is known as Ostwald’s dilu- tion law. If a represents the degree of dissociation of such an electrolyte, of which one mol is dissolved in v liters, the concentration of a the cations and of the anions is —, and of the undissociated Vv a molecules ——. Two reactions are going on at the same time, v the dissociation of the molecules into ions and the recombina- tion of the ions to form molecules. The rapidity of dissociation I—a depends on the concentration of the molecules, ——, and the re- Vv combination on the product of the concentrations of the two . a a Trt a a I—a classes of ions, — X —, and at equilibrium, — xX — = c ——, Vv Vv v Vv v a a as 8 eae . Vv Vv where c is a constant, or —————- = c I—a v a? by division we obtain a =c. From this equation it is v(I—a seen that ionization increases with dilution. Expressed in words, it means that the greater the dilution the farther removed the ions are from one another and the less chance they have of colliding with one another and recombining to form molecules, or the chance of their meeting is equal to the product of the concentration of the anions and the concentration of the cations. This formula does not hold for the strong electrolytes, and Rudolphi (1895) and van’t Hoff have applied the empirical 3 formula, ——-_——- = c, to them. One reason that the strong v(I—a?) electrolytes do not seem to obey the law of mass action may be that they form different hydrates at different dilutions. Some of these hydrates have been crystallized and others detected in other ways. Not only some molecules, but also all ions are sup- 26 PHYSICAL CHEMISTRY posed to be in the form of hydrates. Sulphuric acid forms the following hydrates (see Fig. 5): 5H,SO,-H,O, 3H,SO,- H,O, H50,* H,0, H,S0,+25,0, H,S0;*3H,0, Hye0,*4H,0 and H,SO, - 12H,O, at percentages 96, 94, 85, 79, 65, 58, and 30 of sulphuric acid (C. E. Davis, 1915). It should be emphasized that strong electrolytes exist chiefly as ions in the dilute solutions with which we have to deal in bio- chemistry. Take, for example, the neutralization of HCl with KOH. Since HCl, KOH and KCI take no part in the reaction and are practically nevér present, the reaction becomes H’ + OH’ = H,O. Cl’ and K’ are present in the same quan- tities before and after the reaction takes place. That the re- action is simply the formation of water from its ions is illustrated by the fact that no matter what strong base or acid is substituted for the above (at 20°), 13700 calories of heat are produced for 1 mol of acid and alkali used. Ionization must be considered in studying the solubility of electrolytes. If we pass hydrochloric acid gas into a saturated solution of NaCl, the salt will partially crystallize out. In a saturated solution of NaCl, the product of the concentrations of Na’ and Cl’ is a constant, and when we add more Cl’ by the addition of HCl, salt crystallizes out until the product assumes its original value. (This principle is used in the recrystallization of NaCl by the introduction of HCl gas into the saturated solu- tion.) Some electrolytes dissociate into three or more ions. They disso- ciate by steps, thus K,SO, dissociates into K° and KSO,’ and the latter dissociates into K’ and SO,”. In certain cases the first step may be complete and the second be incomplete under ordinary conditions. The dissociation of H,CO, and H,;PO, will be considered in a later chapter. In case one of the ions of an electrolyte is weak and the other strong hydrolysis may occur. K,CO, dissociates into K* and KCO,’. K’° combines with OH’ of the water and forms KOH while the other ion unites with H* of water to form KHCO,. Since the KOH dissociates more OH ions than the bicarbonate produces H ions the reaction is alkaline. The further steps in this hydrolysis will be considered later. Hydrolysis is the union with the ions of water already present. When these are ex- OF VITAL PHENOMENA 27 5 Surface Tension Deviation “neorhuanrwnon o= 10 20 30 40 50 60 70 80 90 500 B. 10 20 30 40 50 60 70 80 70 100 Percent Sulphuric Percent Sulphuric o> a2 s" é = wo = 2 's ® of 3 A A = 2 —_. ee s = Oo vo ” = = 3s & < 5 S & 01 ° 10 20 30 40 50 60 70 80 90100 0 "lo 20 30 40 50 60 70, 80 70 100 Percent Sulphuric D Percent Sulphuric OQ Ss s s 5 3 3 & eS = = 7) = 9g a 2 OI 30 40 50 60 70 80 70 100 90 100 0 “lo 20 30 40 50 60 70 E Percelt Sulphuric F Percent Sulphuric THR — Fic. 5. Curves indicating the concentrations at which changes in the hydration of sulphuric acid occur (from Clarke Edwin Davis, 1915). 28 PHYSICAL CHEMISTRY hausted more are formed, and the whole process is instantaneous in the above case. In this it is distinguished from the hydrolysis of proteins, for instance, in which the protein is boiled for a long time with acid or alkali, or hydrolyzed by means of enzymes. In the salt hydrolysis water is all that is necessary, but in the case of proteins the hydrolysis occurs with unmeasurable slow- ness in pure water. Some substances may dissociate both H* and OH’, and are therefore called amphoteric electrolytes or ampholytes. The amino acids and proteins belong to this class. Their general formula is NH,RCOOH, in which R represents a carbon chain (or a series of them connected by the amino and carboxyl groups). Some of these may be about neutral, but usually the acid or basic character predominates. The double nature of these substances is shown by their compounds. If HCl is added to egg albumin the latter no longer dissociates H ions, owing to the large number already in solution, but it continues to dis- sociate OH ions and as fast as these are formed their place in the albumin is taken by Cl ions, so that more OH ions continue to form and to combine with the H ions in solution. In this way Alb. Cl is formed, which dissociates into Alb’ and Cl’. If an electric current is passed through the solution the albumin will go to the cathode. On the contrary, if KOH is added to an albumin solution Alb.K will be formed by the displacement of the H of the hydroxyl, and if an electric current is passed the albumin will go to the anode. At a certain reaction of the solution the albumin will not migrate in an electric field, or if it does half will go toward the cathode and half toward the anode. This reaction is called the isoelectric point for that albumin. This subject will be con- tinued in Chapter IV. CHAPTER III OSMOTIC PRESSURE There are some membranes that are freely permeable to water but impermeable to many dissolved substances, and are called semipermeable membranes. An example of such is found in one of Traube’s (1867) membranes. If a solution of potassium ferrocyanide is allowed to come in contact with a solution of CuSO,, a membrane of copper ferrocyanide is formed, which is impermeable to potassium ferrocyanide, CuSO, and their ions and to a certain degree to some other electrolytes such as MgSO, and its ions. If this membrane is made in the form of a bag with CuSO, on the inside and placed in pure water, so much pressure will be developed within it that it will burst. This _ pressure is called the osmotic pressure of the CuSO, solution and can be measured if the membrane is strong enough. Mem- branes may be deposited in the pores of strong clay cups and thickened by driving in the mother substances with an electric current (H. N. Morse, 1914). If such a cup is connected with a mercury or nitrogen manometer so that the osmotic pressure can be measured it is called an osmometer. It was found by de Vries (1884), Pfeffer (1877) and others that 1 gram molecule (mol) of a non-electrolyte, such as dex- trose, dissolved in water to make 1 liter has an osmotic pressure of 22.4 atmospheres at 0°. De Vries found that electrolytes de- parted from this rule, but Arrhenius (1887) showed that this discrepancy could be explained by his theory of electrolytic dis- sociation, since the ions exert osmotic pressure as well as the molecules, and hence ionization would increase osmotic pressure as the total osmotic pressure is the sum of the partial pressure of molecules + ions. Van’t Hoff (1887) pointed out that os- motic pressure of ideal dilute solutions is the same quantitatively as gas pressure. The formula for osmotic pressure of dilute ideal solutions is pv = RT, where p is the pressure in atmospheres, v is the vol- 30 PHYSICAL CHEMISTRY e “V % VY Fic. 6. Graph indicating the method of integrating the formula PV—=RT (from MRR). ume in liters in which 1 mol solute is contained, R = 0.0821, and T is the absolute temperature, in which zero is — 273.090 on the centigrade scale (Fig. 6). Since the volume is the reciprocal of : Pp the concentration, the formula becomes — = 0.0821 T, where c c is the molecular (molar) concentration. If the concentration is 1 and the temperature = 0° C = 273 abs., p = .0821 X 273 = 22.4. In other words, the osmotic pressure of a molar solution is 22.4 atmospheres at 0°. From this a method was developed of determining the extent of dissociation of an electrolyte from its osmotic pressure. If 1 mol KCl is dissolved in so large a volume of water that it is completely dissociated it will exert double the pressure of 1 mol dextrose dissolved in the same volume, because the number of ions is double the number of molecules, and the formula becomes py = 2RT. If the salt is partly dissociated a number somewhere between I and 2 must be used (say 1.5), then 50 per cent of the salt is dissociated. The most accurate determinations of osmotic pressure have been done on sugars by H. N. Morse (1914) and Berkeley and Hartley (1904). Morse made some determinations on elec- OF VITAL PHENOMENA at trolytes, but finds that they increase the permeability of the mem- brane. The results of Morse do not exactly correspond to the formula, and he supposes this due to the fact that the sugar molecules take up so much room that the concentration of the water is reduced. By dissolving the sugar in 1000 g of water instead of making a liter of solution, the formula was more closely followed. Such solutions are called weight normal solu- tions, but the water combined with the sugar molecules is not considered. According to Washburn (1915) each sugar molecule ‘is combined with six molecules of water, which means that in a liter of a mol solution, 108 g of water per liter are taken from the solvent. The significance of the room occupied by the mole- cules is strikingly shown in solutions containing solutes of very high molecular weight. The osmotic pressure of a 30 per cent gum arabic solution is 4 atmospheres, whereas that of a 60 per cent solution is 48 atmospheres. If blood serum whose osmotic pressure is 6 atmospheres is concentrated to %4 volume, its osmotic pressure is 35 atmospheres. Owing to the difficulty of determining the osmotic pressure directly, it is usually calculated from the freezing point. An osmotic pressure of 22.4 atmospheres corresponds to a freezing point lowering (A) of 1.85°. The following conversion table was calculated by Harris and Gortner (1914) from the formula of Lewis (1908). In determining the freezing point of aqueous solutions, the only advantage of the Beckmann thermometer is that it may be accessible. It has the disadvantage that it must be adjusted for aqueous solutions and that the zero point must be determined every year. The curvature and the temperature of the two mercury surfaces bordering on the vacuum are not always the same and hence the vapor pressure of the mercury at these two surfaces is not the same, and consequently mercury distils over from one surface to the other. The Heidenhain thermometer has no adjustment to cause this trouble. It is a simple ther- mometer graduated in hundredths of a degree from about +0.5° to —5°. The Burian-Drucker (1910) thermometer is designed for fluids of which only 1.5 cc may be available. Since it has a smaller bulb and consequently shorter stem, it is graduated in fiftieths of a degree. The thermometer should be kept in ice water several hours before the determination. 32 PHYSICAL CHEMISTRY TABLE OF Osmotic PressurEs IN ATMOSPHERES FOR DEPRESSION OF THE FREEZING Pornt. Hundredths of degrees, centigrade 0 1 2 3 4 5 6 7 8 9 0.0 | 0,000] 0.121] 0.241] 0.362] 0.482] 0.603) 0.724} 0.844] 0.965] 1.085 0.1 | 1.206] 1.327] 1.447| 1.868] 1.688) 1.809] 1.930] 2.050] 2.171] 2.291 0.2 | 2.412) 2.532] 2.652] 2.772] 2.893] 3.014; 3.134] 3.255] 3-375] 3.496 0.3 | 3.616| 3.737] 3.857] 3.978] 4.098) 4.219) 4.339] 4-459] 4-580] 4.700 0.4 | 4.821] 4.941] 5.062] 5.182] 5.302] 5.423) 5.543] 5.664] 5.784] 5.904 0.5 | 6.025] 6.145] 6.266] 6.386] 6.506} 6627! 6.747| 6.867] 6.988] 7.108 0.6 } 7.229] 7.349] 7.469| 7.590] 7.710 7.830) 7.9§1| 8.071] 8.191] 8.312 0.7 | 8.432] 8.552] 8.672} 8.793] 8.913} 9.033) 9.154] 9.274] 9.394] 9.514 0.8 | 9.635] 9.755] 9.875] 9.995|10.12 |10.24 |10.36 |10.48 |10.60 | 10.72 0.9 }10.84 |10.96 |11.08 |11.20 }11.32 }11.44 [11.56 |11.68 |11.80 |11.92 1.0 }12.04 |12.16 |12.28 |12.40 |12.52 |12.64 [12.76 |12.88 |13.00 |13.12 I.I /13.24 |13.36 |13.48 |13.60 | 13.72 |13.84 |13.96 |14.08 | 14.20 |14.32 1.2 |14.44 |14.56 14.68 |14.80 |14.92 [15.04 |15.16 |15.28 |15.40 | 15.52 1.3 |15.64 |15.76 |15.88 |16.00 |16.12 |16.24 |16.36 |16.48 |16.60 | 16.72 1.4 |16.84 |16.96 |17.08 |17.20 |17.32 |17.44 [17.56 |17.68 |17.80 |17.92 1.5 |18.04 |18.16 |18.28 [18.40 |18.52 [18.64 | 18.76 |18.88 |19.00 |19.12 1.6 }19.24 |19.36 |19.48 |19.60 | 19.72 |19.84 |19.96 |20.08 |20.20 |20.32 1.7 |20.44 |20.56 |20.68 |20.80 |20.92 [21.04 |21.16 |21.28 |21.40 |21.52 1.8 21.64 |21.76 |21.88 |22.00 |22.12 |22.24 |22.36 |22.48 |22.60 |22.72 1.9 |22.84 |22.96 |23.08 |23.20 | 23.32 |23.44 | 23.56 |23.68 |23.80 |23.92 2.0 [24.04 |24.16 |24.28 |24.40 | 24.52 |24.03 (24.75 |24.87 |24.99 25.11 2.1 /25.23 |25.35 |25.47 |25.59 |25.71 |25.83 [25-95 26.07 |26.19 |26.31 2.2 |26.43 |26.55 |26.67 |26.79 |26.91 |27.03 |27-15 [27-27 [27.39 [27.51 2.3 {27.03 |27.75 |27.87 |27.99°|28.11 |28.23 28.34 |28.46 | 28.58 |28.70 2.4 |28.82 |28.94 [29.06 |29.18~| 29.30 |29.42 ‘29.54 |29.66 |29.78 |29.90 2.5 130.02 |30.14%130.26 |30.38 |30.50 130.62 (30.74 |30.86 |30.98 [31.09 The solution to be frozen is poured into a test tube having a double bored cork. This tube is sometimes provided with a side neck through which a small crystal of ice may be dropped to start the freezing as soon as the temperature reaches the freezing point and thus prevent undercooling. The test tube is fitted into a larger test tube and the space between them left full of air or filled with alcohol to prevent the condensation of moisture which would obscure observation. The freezing mix- ture is usually crushed ice or snow and salt, but this interferes with observation, and ether through which air is sucked is prefer- able. ; The determination of the freezing point is as follows. About 22 cc of the solution is poured into a test tube, and the bulb of the thermometer and a platinum stirrer lowered into it through separate holes in the stopper. The test tube is cooled nearly to OF VITAL PHENOMENA 33 the right temperature by immersing it in ice and salt; it is then wiped dry and pushed through the bored cork of a larger test tube and returned to the freezing mixture. The thermometer should not touch the wall of the inner test tube, and this in turn should not touch the outer test tube, as the local cooling thus produced might cause a local freezing before the entire solution reached the freezing point. The solution is stirred until freezing commences. The temperature will fall below the freezing point and when the first ice separates suddenly rise to the freezing point. This undercooling may be lessened by having the freez- ing mixture only slightly below the freezing point of the solution or by dropping in a crystal of ice to start the freezing at the proper moment. Since the sudden separation of ice that occurs before the definitive freezing point is reached concentrates the remaining solution, the freezing point lowering is too great and should be decreased 1/80 for every degree of undercooling. Although the cryoscopic method is very simple in principle, it is only by the most painstaking performance that an accuracy of .oo1° is obtained. Since a A of 1.85° corresponds to an osmotic pressure of 22.4 atmospheres, .oo1° represents a pressure of .ogi2 atmospheres or 9.2 mm of mercury, and is very serious when small differences in osmotic pressure are to be measured. It should be remembered that the cryoscopic method determines the osmotic pressure at the freezing point of the solution, and this should be reduced to the desired temperature by correcting for the effect of the temperature change on the electrolytic disso- ciation and osmotic pressure. A method for determining the freezing point of small amounts of solution, devised by Barger (1904), has been called'a micro- tensimeter, but it is in reality an osmometer in which air forms the semipermeable membrane. It consists of a capillary tube that can be observed under a microscope having an ocular mi- crometer. The osmotic pressure of the solution is approximately known from previous data or a preliminary test. A graded series of solutions is prepared, the extremes of which will fall on the two sides of the osmotic pressure of the unknown. Drops of the unknown solution alternating with the known solutions are drawn up into the tube and their lengths measured. After an interval of time their lengths are again measured and the drop 34 PHYSICAL CHEMISTRY of unknown that has not changed in length found; its osmotic pressure is between those of the graded solutions on each side of it. One cc of the unknown is sufficient and hence the method is useful in biological work. This method has the advantage that it measures the osmotic pressure at any desired temperature. The chief error is in the mixing of the drops, caused by the adhesion of a surface film to the glass and the transfer of fluid from one drop to another in this film. The way in which osmotic pressure may do work in the or- ganism is best illustrated in plants. The plant cell is limited by the plasma membrane which is impermeable to some dissolved substances. Surrounding the plasma membrane is the cellulose cell wall. If the cell is placed in water the osmotic pressure of its interior causes it to swell, and the plasma membrane is pressed © against the cellulose cell wall and tightens it or makes the cell turgid. This turgidity (turgor) is what gives stiffness to herba- ceous plants, lacking which the plant is said to be wilted. The osmotic pressure of many plant cells is a number of atmospheres, and the cell wall has to be very strong in order to withstand the pressure. The extent of this pressure is realized when the roots of trees growing between rocks separate the rocks by the osmotic pressure exerted. The cell wall of a young plant cell is very thin and is stretched by the osmotic pressure as the cell grows. Some mechanism must be provided for getting the osmotic substance into the cell, before it can stretch the cell and cause growth. In the green plant cell the osmotic substances are manufactured with the aid of sunlight out of H,O and CO,, to which the cell is freely permeable. The colorless cells absorb certain organic substances secreted by the green cells, transforming them into other sub- stances to which the plasma membrane is impermeable, and which therefore accumulate in the cells and cause the osmotic pressure. Though these osmotic substances are not in all cases definitely known, tannic and oxalic acid and their salts have been postu- lated. The sugars are supposed by some investigators to be the nutritive substances passed from the green to the colorless cells, meaning that both kinds of cells are permeable to sugar. Over- ton, however, claims that plant cells are impermeable to sugar OF VITAL PHENOMENA 38 and hence any contained sugar could aid in maintaining the turgor. A solution whose osmotic pressure is lower than that of the cell is said to be hypotonic, and one whose pressure is greater, hypertonic. The osmotic pressure of many animal cells is very near that of the medium, or the fluid which bathes them. When the medium is hypotonic the cell swells, when hypertonic it shrinks until equilibrium is established. Since animal cells are not surrounded by very strong cell walls, they burst or swell when placed in pure water. But some animal cells are imper- meable to water, and consequently are not affected by changes in the medium. Fresh water protozoa are prevented from bursting by the activity of the contractile vacuole. Zuelzer (1907) acclimatized Ameba verrucosa to sea water and the contractile vacuole beat more and more slowly and finally disappeared in 14 sea water. The few marine protozoa that have contractile vacuole are parasitic and hence not in pure sea water and the pulsations of the vacuoles are much slower than is the case with fresh water forms. Most of the cells in the mammalian, reptilian and avian bodies are bathed by fluids whose osmotic pressure is practically con- stant. One of these fluids is the blood. Its osmotic pressure at body temperature is about 8 atmospheres (6.7 at 0°), its freezing point being about —.56°. This corresponds to about 10 per cent (.3 molecular) cane sugar or .95 per cent NaCl solu- tion (.16 mol). See Fig. 30, Chapter XV. More minute data on osmotic pressure will be considered in Chapter XV. CHAPTER IV HYDROGEN AND HYDROXYL ION CONCENTRATION AND CO, PRESSURE Water is an electrolyte and dissociates into H and OH ions, which are therefore equal in number. At 22° or 23° H’ = OH’ = 107, or H’ & OH’ = 10. If we increase H’ by adding acid, OH’ decreases, because H” & OH?’ remains equal to 107+. Conversely, if we add alkali, H’ decreases, and hence we may estimate the acidity or alkalinity of a solution by determining the H° concentration. The product of the H and OH ion concentrations is to* and the — logarithm is 14 (and is designated — log K,,). The following table gives the values of —logK, for various temperatures, calculated thermo- dynamically from the results of Lorenz and Boehi (1909) at 18°, and which agree with those of Sorensen, Michaelis and some others within about one degree. t° —logKwit° —logKw)t® —logKwjt® —logkKw)t° —logKwit° —logKw 18 14.142 |22 14.004 |26 13.861 !30 13.733 |34 13.611 |38 13.513 19 14.108 {23 13.960 |27 13.828 |31 13.702 /35 13.581 |39 13.475 20 14.073 |24 13.927 |28 13.796 |32 13.671 |30 13.561 |4o 13.446 21 14.038 }25 13.894 |29 13-765 |33 13-641 |37 13.532 In order to save space it is better to express H" concentration as the minus logarithm (PH). Thus if H* concentration = 107, PH = 7 (Sorensen 1909). In order to understand the method by which the H ion con- centration is determined we must first consider the theory of concentration cells and electrode potentials. The fact that an electric potential difference is produced at the surface of con- tact of the metal with a solution is explained as follows: We know that the ions of metals are soluble because they are pro- duced by the solution of metallic salts. There is also a store VITAL PHENOMENA 37 of electricity in the metal for charging the ions as illustrated by the behavior of radioactive metals. If a piece of metal is placed in pure water it gives off ions, but these ions taking positive charges from the metal leave the metal negative, and when the attraction of the negative metal for the positive ions equals the diffusion pressure (= osmotic pressure) of the ions no more ions will be given off. If instead of placing the metal in pure water we place it in a solution containing ions of the metal, the metal will give out a less number of ions and will become less negative. If the concentration of the metallic ions in the solu- tion is increased, a point will be reached at which the metal will give out no ions and hence remain electrically neutral, and if the ionic concentration of the solution is still further increased ions will be deposited on the metal and give it a positive charge. If a piece of metal is placed in a solution containing 1 gram equiva- lent of its ions per liter it may become negative or positive ac- cording to the metal used. The following table is prepared in this way, but the neutral point (taken arbitrarily) is not the potential of the earth but the potential of a hydrogen electrode in a gram equivalent solution of hydrogen ions (see Abegg Auer- bach & Luther, 1911). The potential that the electrode assumes is called the electrolytic solution tension. ELectrotytic SoLuTION TENSION. Potential of metal (or non-metal) when immersed in a normal solution of its ions at 25°, as measured against a normal hydrogen electrode. Some American writers use reverse signs (+, —). ‘Cs Sn** — Pl + .789 ILi® — 3.305 Fe’? — .43 Pe + 863 Rb* — 3.205 Tl — .32 Aw + 15 KK’ — 3.203 Co*? — .29 HSO,'+ 2.6 Na°® — 2.993 Ni°* — .22 SO,” + 19 Ba®* — 2.7 Pb.% 02 OH’ + .41 Sr°° — 2.767 H’ 0.00 CY + 1.35 Ca®* — 2.55 As + .292 Br’ + 1.08 Mg** — 1.55 Cu"? + .34 vo + 454 Al — 1.276 Bi + = .391 Fo +109 Mn — 1.075 Sb + .466 Ss" — 155 Zn°* — .760 Hg** + 86 Cd** — .40 Ag? + 8 It may be seen from the table that the baser metals have a greater tendency to dissolve and produce ions than the noble metals. Electrolytic solution tension is reduced by certain impurities 38 PHYSICAL CHEMISTRY in solution as follows, beginning with least effective: mannite fa— Cut x 1078 x 10°7 H~ S we TTT LTE, ~~ DP Fig.19. Table for converting millivolts into Py and Cu, using 0.1 N KC] calomel electrode. OF VITAL PHENOMENA 49 range of temperatures. All these corrections are combined in the following table from Clark and Lubs: ‘Correction in millivolts to be added to potentiometer reading, for change in concentration of hydrogen due to barometric pressure, tempera- ture and vapor tension of water. Barometer (mm) 20° 25° 30° 780 0.85 1.19 1.57 770 1.02 1.36 1.74 760 1.19 1.53 1.92 750 1.36 L71 2.10 740 1.53 189 062.28 Determination of Hydrogen Ion Concentration by Means of Indicators According to Ostwald, indicators are weak acids or bases whose ions are not colored like the undissociated molecules. Indicators may, however, be used in titration in non-aqueous solvents in which dissociation is very slight. The theory of Stieglitz that the change in color is due to intramolecular change, following change in ionization, may account for the fact that the change in color may not be instantaneous. It is possible that the amount of hydration of the ions has an effect on their color, since the presence of neutral salts affects the color of indicator solutions. The following indicators and PH at which they change are given by Friedenthal : Indicator PH Indicator PH Alizatin occ cecaaus es 6- 8, 11-15 Lacmoid ............. 4-8 Alizarin blue S........ 11-13, 7-8 | Magdalarot 3-4, 14-15... 3- 4, 14-15 Alizarin green B...... 12-13 Moativein -asanccesis tee O- 3, 13-15 Alizarin Na sulfonate. 4- 6 Methyl green ......... O- 2, 11-14 Alkali green ......... 3-7 Methyl orange ........ 2- 5, 14-15 Azolilmin (litmus) .... 5-9 Methyl violet ......... O- 3, 12-15 Benzopurpurin B ..... O- 5,13-14. a-Napthol benzoin..... Q-II Bitteralmondoilgreen.. o- 2,11-14 Neutral red .......... o- I, 7-9 Cochineal ............ 4- 6 p-Nitrophenol ........ 5-7 Congo red ............ 3-5 Phenacetolin ......... 3- 6, 10-13 GCrocein wa ssacscdenscws 12-14 Phenolphthalein ...... 8-10, 13-15 Curcumein (Tumeric). 13-15 Rosolic acid ......... 6- 8, 13-15 Cyanin, 3..egc0 esse 6-8 Safranitl.. asiwsone eee ee O- I, 14-15 Dimethylamidoazobenzol 2- 4 Saurefuchsin (Acid Echtrot: s4% sscugcensas O- I fuchsin) ............ 9-14 Eosinmethyleneblue ... 0- 3, 14-15 Tetrabromphenolphtha- Fluorescein .......... o- Vein; nsiamaaiseks 0204 8- 9, 12-15 Gall€ii> .cbcisnenivee ees 1- 6,10-14 Thymolphthalein ...... ro-11 Gala scxcasowinere kes 7-8 Tropaeolin ........... 7-9 Haematein ........... O-I5 Tropaeolin o ......... 11-13 Heliantin I ........... II-13 Tropaeolin 00 ........ o- 3 Heliantin IT .......... 12-14 Tropaeolin 000 ....... 11-13 Todeosin .........000-- 0-15 Trinitro benzol ....... 12-15 50 PHYSICAL CHEMISTRY The following indicators were found by Sérensen (1909) to be least affected by proteins, but some control is necessary if the protein content of the unknown solution is considerable. Indicator PH Methyl Violet c.cée deacueccacutar se aatdmamaanne nd PA pr euacei sya O.I— 3.2 MaUVeli wr. nace. out dah cnghes oeremuNee Ama Ae eames Param O.I— 2.9 (Methyl red) o—Benzolcarbonicacid azo dimethyl anilin....... 4.2— 6.3 p—Nitro phenol Neutral red ...............0., iE Rea Mo eetainte de Seda Shae h es ea keONS FRO SONG ACE siisyasiea ciedeig S858 0S era nd honeaparamuerontaa push Le rk See oar (Tropaeolin 000) p—Benzolsulfonicacidazo-a-napthol........... 7.6— 8.9 a—Napthol phthalein ........ 0... ccc cece ccc ence teenies 7.3— 8.7 Phenolphthalein 24:07 .elwosse seus 4 gm awsewuakn veleees teeaaelstny 8.3—I0 ‘Lhymolphthalein:. saneess os eee sock eA ee asaee Ae ated eee ead os 9.3—10.5 The following indicators were studied by Clark and Lubs (1915): Indicator PH Monomethy! 6d) soauiincinnpeaktaraiasandennaaeaienadeereaad 4.25—6 Monoéthyl red’ agconie aiveniay chcanda s coetecan tea eee 4.25—6 Diethyl, Ped ac aysuciehdins oy ndash a cee uns oe gists Ber dsia i heainedeee ais 4.5 —60.5 Monopropyl ted. aasxisciaccescoxe gs Paneeeed Mu beee ieeressesnad 4.25—6.25 Dipropyl red). accnswseec oe auns caedhyedaratbans berpeaeeaeaceage 4.5 —6.5 Dimethyl-a-napthylamine red ........... 0... e cece eee ene 5. —6.75 Phenolsulphonephthalein ......... 0... cece eee eee eee eee 6.5 —8.5 o—Cresolsulphonephthalein ............. 00 ccce eee cence eee 6.5 —8.5 Thymolsulphonephthalein .cces ages rsvimeesaeye rasa b eases nya sceeia 8 —9.75 a—Naptholsulphonephthalein ............. 0.0 cece cece eens 7.5 —9. Tetrabromphenolsulphonephthalein ............ 0... e eee ee 3.5 —4.5 Dibromthymolsulphonephthalein 1.0.0.0... 000... eee ee eee eee 6. —7.25 The color change and PH of solutions of some useful indi- cators were shown in a colored chart. In order to find the PH of an unknown solution, pour it into a test tube of 1 cm bore, add 0.1 cc of the indicator solution, and while looking down into it against a white background, compare it with the chart. If the test tube is 2 cm bore, .4 cc of indicator solution should be used. (McClendon, 1916, b; also in Tortugas Vol., Carnegie Ins. Wash., in press.) As shown by Sdrensen (1909) some indicators are more sensi- tive than others to neutral salts, proteins and protein decomposi- tion products. Congo red and litmus are therefore to be especially shunned in biological work. For solutions containing large amounts of proteins, or having a color of their own, the method of Rowntree, Marriott and Levy, 1915, is useful, pro- vided that obvious extra precautions are recognized. The fluid to be tested is placed in a dialyzing capsule of collodion or parch- ment paper impermeable to protein, and introduced into a test tube containing some neutral (boiled) distilled water or salt solu- tion. The test tube is stoppered to prevent the loss of CO, and OF VITAL PHENOMENA 51 dialysis allowed to proceed to approximate equilibrium. The capsule is removed and the right quantity of indicator added. The color is compared with that of a series of tubes of the same bore, containing the same amount of indicator and solution but of known PH. (Such tubes may be obtained, sealed, from Hynson, Westcott and Co., Baltimore.) Or the tube may be compared with the colored chart. One effect of dialysis is to dilute the solutes affecting the PH and causing an error which is less the greater the buffer value of the solution. Buffers and Solutions of Standard Hydrogen Ion Concentration The PH of water, or solutions of neutral salts, or very dilute solutions of strong acids or alkalis, is changed by minute traces of certain impurities. Absolutely pure water (conductivity water) is neutral but may not remain so. If exposed to the air it becomes acid due to absorption of CO,, and if kept in glass it becomes alkaline, due to solution of the glass. “Pyrex” or “nonsol” glass is better in this respect, but any glass is improved by allowing a jet of steam to condense on the surface and drain off, a process known as steaming out. Silica or metal vessels are more reliable. This difficulty in maintaining fixed hydrogen ion concentrations is obviated by the use of buffers. The chief buffer in organisms is NaHCO,. The reaction of a pure solu- tion of NaHCO, is but very slightly alkaline, that of Na,CO, somewhat more alkaline and that of CO, but slightly acid. If we add a strong acid to a solution of NaHCO, the acidity of the mixture will not exceed that of a solution of CO, until all of the NaHCO, has been decomposed. If we add a strong alkali to a solution of NaHCO, the alkalinity of the solution will not exceed that of a Na,CO, solution until all of the NaHCO, has been decomposed. One drop therefore of n HCl would acidify a liter of H,O or neutral salt solution more than a liter of the acid would acidify a liter of m NaHCO, solution—hence the advantage of a relatively high concentration of buffers in stand- ard solutions. The standard solutions used by Sorensen (1912) are shown in the chart in Fig. 20. On the ordinate is given the number of cc of the first solution of a pair to be taken, when the second solution is to be added to give a total volume of 1o cc. The stock solutions are as follows: 52 PHYSICAL CHEMISTRY “HCl” = A o.1 n solution of HCl titrated with silver nitrate. “NaOH” =A o.1 n solution of NaOH made by adding an excess of sodium or sodium amalgam to CO,-free H,O and titrating with HCl and diluting to .t n. Or decanting a clear saturated solution of NaOH and diluting to required volume with CO,-free H,O. “Citrate? = A o.1 m solution of secondary sodium citrate made by dissolving 21.008 g citric acid in 800 cc of .25 n NaOH and diluting to a liter. A layer of ether on top will preserve it. “H,PO,” = A 1/15 m solution of H,PO, accurately stand- ardized. “KH,PO,” = A 1/15 m solution of KH,PO, made by dis- solving 9.078 g of the recrystallized anhydrous (desiccated) salt to the liter. “Na,HPO,” = A m/15 solution of Na,HPO, made by dis- solving 11.876 g to the liter, of Na,HPO,2H,O that has been recrystallized and dried until it has the right water content by analysis. “Borate” = A solution of 12.404 g of recrystallized desiccated boric acid + 100 cc n NaOH solution made up to 1 liter. The distilled water used in making these solutions should be free from NH, and CO,. The CO, may be practically eliminated by boiling 15 minutes in a tin vessel and cooling under a soda’ lime tube. All solutions should be kept in “nonsol” or “pyrex” glass vessels or in paraffined bottles and those with PH above 5 should be provided with soda lime tubes. The reagents should be the purest. In dropping metallic sodium into water O, should be excluded. NaOH made from Na may be purchased but should be freed from carbonate by making it first an 80 per cent solution in a stoppered bottle and allowing the carbonate to pre- cipitate, then pipetting off the clear solution, diluting with CO,- free water and standardizing it. All of the salts should be dis- solved in boiling H,O, filtered and crystallized at least once. It is difficult to obtain pure phosphates. The Na,HPO, solution should turn phenolphthalein a deep red. In the chart, Fig. 20, impurities in the reagents affect the ends of the curves more than the middle. The buffer mixtures of Clark and Lubs (1916) are as follows: OF VITAL PHENOMENA 53 Fic. 20. Sorensen’s chart of buffer mixtures. On the ordinate is the number of cc of the first solution when the mixture is completed to 10 cc with the second solution indicated on the curve. On the abscissa is the PH at 18° (from EP), 54 PHYSICAL CHEMISTRY 1, Solutions made up to 200 cc and containing 50 cc 0.2 m KH-phtha- late + 02 n HCl | 46.70 39.60 32.95 26.42 20.32 14.70 9.90 5.97 2.63 PH at 20° 22 24 26 28 30 3.2 34 36 38 2. Solutions made up to 200 cc and containing 50 cc 0.2 m KH-phtha- late + 0.2 n NaOH | 0.40 3.70 7.50 12.15 17.70 23.85 20.95 35.45 39.85 43.00 45.45 47.0 PH tat 20° [40 42 44 46 48 50 5.2 54 5.6 58 60 62 3. Solutions made up to 200 cc and containing 50 cc 0.2 m KH,PO, + 50 cc 0.2 n KCI + PH at 20° |5.8 60 62 64 66 68 70 7.2 74 76 78 80 0.2 n NaOH | 3.72 5.70 Eto Ente TBO 2508 2938500 2.20420 45 204060 4. Solutions made up to 200 cc and containing 50 cc of 0.2 m H,BO, + o2n NaOH | 2.61 3.97 5.90 8.50 12.00 16.30 21.30 26.70 32.00 36.85 40.80 43.9 PH at 20° |78 80 82 84 86 88 90 92 94 96 9.8 10.0 These solutions should be made from the purest reagents, that have been recrystallized three times. The acid potassium phthalate, acid potassium phosphate, and potassium chloride may be dried at 110° but the boric acid must be dried at room temperature in a desiccator. The more acid of the mixtures will deposit crystals of phthalic acid if not kept considerably above 20°. It may be inferred that the buffer value of these solutions is less than those of Sorensen, but their salt action on indicators is also less. Dissociation Constants of Acids and Bases Acids and bases differ from neutral salts in that among their dissociation products are the ions of water, H* or OH’ as the case may be. Since the strength of acids and bases lies in the number of H and OH ions they dissociate, it is determined by the dissociation constant, c. 2 From the law of mass action we have: c = eh where v(1I—a) v is the number of liters in which 1 mol of the acid (for in- stance) is dissolved, r—a represents the proportion of the un- dissociated molecules and a represents the proportion of anions = cations. If we increase the dilution, v, then a? increases and therefore (a =H") increases. (H’ per liter decreases.) Strong acids appear to disobey this law when dissociation is determined by electric conductivity. If ¢ is determined from the dissociation of a more concentrated solution, a more dilute solution is fotind to be dissociated less than is calculated from the formula. In other words, the dissociation in concentrated OF VITAL PHENOMENA 55 solutions is more than is expected. The anomaly may be ex- plained by the hypothesis that the hydration of ions is less in the concentrated solution, they move faster and increase the con- ductivity, and, hence, the high dissociation is only apparent (G. N. Lewis). The dissociation of concentrated solutions of HCl as calculated from electrode potential (J. Ellis, 1916) is much greater than that calculated from conductivity data. The two curves for dilute solutions are shown in Fig. 21. n HCL i Fic. 21. Curves showing the difference between the dissociation of HCl as measured by electric conductivity (conductance ratio) and electrode potential (hydrogen ion concentration). In a molecular solution of an acid v = 1 and the formula a? H’xA’ becomes: c = = ———., where H’ and A’ represent a—I HA 56 PHYSICAL CHEMISTRY the concentration of the ions and HA of the undissociated mole- cules of the acid. The dissociation constants of some weak acids and substances which dissociate traces of H’, are as follows at 25° (mostly from Scudder, 1915): —log Ky Acid —log Ky Acid — .o2 Trichloracetic 10,22 Carbonic (CO,”) +1.00 Oxalic II.00 Chloral hydrate 1.29 Dichloracetic 11.74 Maltose 1.96 Phosphoric (H,PO,’) 12.06 Levulose 2.81 Monochloracetic 12.23 Dextrose 2.06 Salicylic 12.23 Lactose 3.01 Tartaric 12.43 Arabinose 3.08 ‘Citric 12.44 . Phosphoric (PO,”’) 3.40 Malic 12.72 Sucrose 3.05 Hippuric 13.47 Mannite 3.68 Formic 14.15 Glycerol 3.82 Acetoacetic 14.74 Propionitrile 3.85 Lactic 4.17 Succinic —log Kp Base 4.18 Benzoic 2.80 Piperidine 4.25 Acrylic 2.90 Diethylamine 4.44 Adipic 3.25 Ethylamine 4.49 ‘Gallic 3.87 Dimethylamine 47 Betaoxybutyric 3.39 Methylamine 4.73 ‘Acetic - 4.07 Ethylenediamine 4.80 Butynic 4.22 Trimethylamine 4.82 Valerianic 4.34 Allylamine 4.84 Propionic 4.74 Ammonia 4.84 Caproic 4.77 Brucine 4.84 ws 5.58 Quinine 5.80 6.07 Strychnine 5.80 Saicyl aldehyde 7.00 Atropine 6.00 Tannic 7.00 Pilocarpine 6.05 Phosphoric (HPO,”) 8.64 Pyridine 6.19 Cacodylic 9.30 Aniline 6.52 Carbonic (HCO,’) 9.50 o-Toluidine 7.24 Hydrogen sulphide 9.58 Methylaniline 0.24 Boric (H.RO,’) 9.62 Dimethylaniline 9.33 Hydrocyanic 9.80 Ethylaniline 9.92 Phenol 13.80 Urea The temperature coefficient for the dissociation of acids and bases is usually small. In case of CO, and NH,, the above figures show only the apparent dissociation constants. The real acid and base are H,CO, and NH,OH, but the concentration of these is unknown. According to the investigations of Thiel and Strohecker (1914) the dissociation constant of H,CO, is greater than that of formic acid, OF VITAL PHENOMENA 57 Dissociation of Amphoteric Electrolytes (Ampholytes) Ampholytes dissociate both H and OH ions, having therefore two dissociation constants, K, and Kp. A pure solution of an ampholyte has an acid reaction, if Ka is the greater, and an alkaline reaction if Kg is the greater. The following table gives the dissociation of some amino acids and dipeptides at 25°. Ac- cording to these figures, mostly from Scudder (1914), the dipep- tides are dissociated to a greater extent than the amino acids from which they are formed, and the dissociation of H” has in- creased more than the dissociation of OH’, making the dipeptides more strongly acid than the amino acids. PH of Iso- —log Ky Ampholyte —log Kp, electric Point 3.85 ‘Aspartic acid 1.92 3.03 4.39 Glutamic acid easel diate 4.79 m-Aminobenzoic acid 10.91 3.79 4.92 p-Aminobenzoic acid 11.63 4.20 7.74 Glycylglycine 10.70 5.52 7.74 Alanylglycine 10.70 5.52 7.82 Leucylglycine 10.52 5.66 8.16 Taurine Mites scacier 8.28 Asparigine 11.74 5.27 8.40 Tyrosine 11.58 5.41 8.66 Phenylalanine 11.89 5.35 8.66 Histidine 8.24 7.21 9.70 Alanine / 11.28 6.72 0.74 Glycine 12.55 ° 6.58 9.74 Leucine II.49 6.54 II.00 Lysine 7.00 9.00 13.06 Arginine 7.00 10.48 These dissociation constants show the relative dissociation of H and OH ions by an ampholyte when dissolved in a neutral solute. But the addition of an acid to the solution will reduce the dissociation of H ions and the addition of a base will reduce its dissociation of OH ions by the ampholyte, according to the law of mags action. At a certain reaction of the solution for each ampholyte, the dissociation of H and OH ions will be equal. The “remainder” of the molecule will be therefore neither electronegative nor positive, but neutral or isoelectric. The re- action at which this occurs is called the isoelectric point. Accord- ing to Michaelis the PH of the isoelectric point is one half of (—logKw)-+ (—logK,)—(—logKg) and the PH so calculated agrees with the PH found by experiment. Isoelectric points are given in above table, those of proteins in Chapter VI. CHAPTER V SURFACE TENSION AND ADSORPTION We are sometimes surprised at the strength of the surface film when we see insects supported on the surface of water, but according to Colton (1910) a small clam suspended itself by threads (byssus) attached at only three points from the surface film in the Naples aquarium. This is more surprising when we realize that the thickness of the film is .coocc006 mm. Although instances were already known, it was first formu- lated by J. Willard Gibbs (1874) into a general rule that sub- stances which lower the surface tension of a solvent become more concentrated in the surface film than in the interior. Take for example a system of two phases, oil and water. If a substance which lowers the surface tension of water be dissolved in the water it will concentrate in the surface film, next to the oil. If the substance be soluble in oil, it will diffuse into the oil until an equilibrium is reached between the concentration of the sub- stance in the oil and in the surface film of the water. If this substance therefore has the same solubility in water and in oil and does not lower the surface tension of oil it will become more concentrated in the oil than in the water. If the substance be insoluble in the oil it will remain concentrated in the film of water next to the oil and is said to be adsorbed by the oil. Hence, surface tension, adsorption and diffusion are related phenomena. In the phase boundary between two fluids it is easier to meas- ure the surface tension than the adsorption. On the contrary it is impossible to measure the surface tension in the phase boundary between a fluid and a solid, but the adsorption may be measured, actually or relatively. The most practicable method of measuring surface tension, in biochemistry, is the estimation of the average weight of a drop of the one of the fluids falling from a standardized pipette into the other fluid. In most measurements one of the fluids VITAL PHENOMENA 59 AMH* 001 000! -000001 0006001 VA 2 3 a 1 2 3 Charts showing the hydrogen ion concentration of the stomach (on the ordinate) and time after eating (on the abscissa). ‘Curves 1-4 from same man with different quantities of food. Curve 14 is the average curve for infants. is air, and the drop is hence allowed to drop out of the pipette into the air. The diameter of the dropping surface = 4.6 to 5.7 mm (J. L. Morgan, 1915). One form of pipette is Traube’s (1904) stalagmometer. In its use, the weight of the drop is found by multiplying the volume of the drop by its specific grav- ity, the volume of the drop found by dividing the volume of the pipette by the number of drops from one filling. The pipette is standardized with water, whose surface tension is taken as unity. Therefore the surface tension = specific gravity of solution X no. of drops of water number of drops of solution Traube’s (1912) viscostagmeter is a dropping burette with which the volume of say ten drops is measured, and is more rapid than the stalagmometer, which holds forty to 100 drops of water. (Stalagmometers are made to order by Kimball Durand Co., Chicago.) It is the presence of the substance in the surface film which lowers the surface tension, but it is not until diffusion into the surface film has reached an equilibrium that the lowest surface tension is present. For instance, soap very greatly lowers the -surface tension of water, but when measurements are taken on new surfaces by the instantaneous method of Rayleigh, the surface tension of the soap solution is found to be the same as # ha 60 PHYSICAL CHEMISTRY that of water. If the soap solution is allowed to drop slowly from a stalagmometer it shows a lower’ surface tension than if dropped fast. The rate of flow from a stalagmometer is reduced by a piece of capillary tubing forming part of the outflow tube, but the more viscous the fluid the slower it will flow. In order to reduce errors from this source, Traube uses three stalag- mometers for solutions of different viscosity and selects one de- livering less than one drop per second. The error in using the stalagmometer, due to lack of diffusion equilibrium, is less than the error in the methods used on old surfaces, due to the forma- tion of haptogen membranes. It should be remembered, how- ever, that the stalagmometric data are merely comparative, and only those results should be compared where the flow is slow and its rate approximately the same in each case (see Harkins and Humphrey, 1916). Fic. 22. Scheme showing that surface tension is located in a film whose thickness equals the diameter of the sphere of molecular attraction. In order to understand the relation between surface tension and osmotic pressure certain theoretical considerations are neces- sary. Surface tension is a molecular phenomenon. The thick- ness of the surface film equals the radius of the sphere of molecular attraction. In Fig. 22, suppose 7 to represent a mole- cule in the interior, M@ a molecule on the surface of a liquid, and the circles around them to define the spheres of molecular attrac- tion. The sphere of m is entirely within the liquid, hence m attracts and is attracted equally on all sides by all molecules in this sphere. On the contrary, only the hemisphere of M is within the liquid and, hence, M is attracted laterally and downward, but not upward. This attraction which the molecules in the surface film have for one another puts the film under a tension—surface tension. OF VITAL PHENOMENA 61 If the surface be convex the surface tension is greater, in- creasing with the convexity. In Fig. 23, 1 and M are two mole- cules equidistant beneath a plane surface (i) and a convex surface (M). These molecules attract and are attracted by the Fic. 23. Scheme showing that convexity increases surface tension and concavity decreases it. molecules within the lightly shaded areas, the spheres of molecu- lar attraction. The uncompensated downward attractions are represented by the more deeply shaded areas. The area is larger in the convex film and, hence, the surface tension greater. The interior of a drop of a liquid is under a hydrostatic pres- sure due to its surface tension, the pressure being greater the smaller the drop. Imagine a spherical drop bisected by a plane. If the surface tension is unity, the pull of the surface film on the plane = 2™r = the hydrostatic pressure on one side of the plane = ptr*, where p is the pressure. Since ptr? = arr, 2™r 2 P= a = ae hence when r is small p is large, or when the radius is small the pressure is large. Thus, the pressure is greater in small drops when the surface tension remains the same. But it was shown above that the surface tension is greater the smaller the drop (the greater the curvature). Hence, the pressure is increased in two ways. _ Now suppose the surface film of a drop of liquid that floats in another liquid of equal osmotic pressure to be semipermeable. The surface tension of the drop causes a hydrostatic pressure in its interior and pure water will be squeezed out through the surface film until the increase in osmotic pressure equals and replaces the hydrostatic pressure due to surface tension. Hence surface tension increases osmotic pressure. Without knowing the surface tension of protoplasm we cannot estimate the effect of surface tension on the osmotic pressure 62 PHYSICAL CHEMISTRY of cells. Quincke assumed that the surface tension of proto- plasm is the difference between the surface tension of water and that of a certain albumin solution. From this assumption the os- motic pressure of Micrococcus progrediens (diameter = .16 mm) would be 5.75 atmospheres greater than the medium, without taking into account the increase in surface tension due to con- vexity. This effect decreases rapidly with the diameter of the cell, for one of .o2 mm diameter being only .o46 atmospheres. Surface Tension of Aqueous Solutions As a rule, inorganic neutral salts, and many sugars, very slightly raise the surface tension, whereas acids, bases and most organic substances lower the surface tension. The lowering is not proportional to the concentration, but when a small amount of the substance lowers the tension a certain degree, each addi- tion of the same amount has less and less effect, Fig. 24. 10 Sal 05 0:5 mo Fic. 24. Surface tension-adsorption curve (adsorption isotherm) of butyric acid (from a class experiment). The surface tension relative to pure water is plotted on the ordinates and the mol concentration of the butyric acid on the abscissae. A curve similar to Fig. 24, which is the typical surface tension adsorption or adsorption isotherm curve was first figured by Dupré (1866). The necessary consequence of the shape of this curve is that the solute reducing the surface tension is adsorbed. This relation, demonstrated by Dupré and formulated a few years later by Gibbs, was first called to the attention of physiolo- gists through the comparatively recent writings of Wilhelm Ostwald, OF VITAL PHENOMENA 63 The following table gives the surface tension at 15° of .25 molecular solutions of some non-electrolytes, according to Traube. It may be seen that sugars and amino acids raise the surface tension, urea is inactive, trihydric alcohols and amides lower it slightly, and monohydric alcohols, ketones, nitrils, and organic acids and their esters lower it very much. In homologous series the effect is greater the longer the carbon chain. According to Traube it requires only one-third the molecular concentration of one member of the series to lower the tension as much as the preceding member. .25 mol s.t.at 15° .25 mol s.t.at 15° Cane sugar ccs ds shccan woos 1.007 Propionic acid .............. 83 Grape sugar l Oth Methyl acetate ............... 83 Mannite fcc 2004. Propyl alcohol ............... 8 Glycocolll saison veeaen ceeeneen 1.003 Methyl ethyl ketone.......... 707 Water ccisscacnes cae ide cannons I Diethylamine ................ 75 TITOAy ai vo lsncunsaueiee a8 2 ack Joiautonteecs T Piperidine ...........-...0-- 738 Glycerine .......... 00. cee ees = Ethyl ether esa: cwaacoteconsquiins 73 Glycol. senccaiiientnss dee epad eases Peyiri@ ine: \shaptin ioweteis'e nea clanai 73 Acetamid. ccscex ices kes epee 6 Paraldehyde ................. 7 Methyl alcohol .............. Chloral hydrate .............. 695 Acetic ACH occ ed ied ces eenee Ms Butyrie acid. ... sc cec che eesis ee Aceto nitrile ...............5. 95 Isobutyl alcohol . vk 2 Ethyl alcohol 92 Tert. Amyl alcohol........... Acetone. ss snssmas aie sveee cay 88 Ethyl acetate............. 58. Bs Ethyl urethane .............. .87 Isoamyl alcohol .............. “42 Propionitrile ................. 842 Although small amounts of some substances may reduce the surface tension of water to less than half, no substance raises it very much. The explanation is that the substance which lowers the surface tension becomes very concentrated in the surface film and has its maximal effect, whereas the substance which raises the surface tension is driven from the surface, consequently reducing its effect. The salts of mineral acids and alkalis slightly raise the surface tension whereas HCl and HNO, lower it. An electrolyte brings with it the added effects of the ions and molecules. Surface tension is reduced by the colloids from organisms, but since we do not know their molecular weight we cannot compare them quantitatively with other organic substances. The colloid concentrated in the surface film becomes very viscous, finally forming a membrane insoluble in water. These so-called haptogen membranes form on the surface between water and air, ether, carbon bisulphide, chloroform and many solids. By 64 PHYSICAL CHEMISTRY shaking the solution the colloid may be precipitated in the form of torn membranes, which assume a stringy appearance. In this way enzymes may be inactivated, being ‘either colloidal or pre- cipitated with colloid impurities. The presence of colloids makes an emulsion of oil and water permanent by forming haptogen membranes around the oil drops. It is the haptogen membranes on fat globules in milk that keeps it permanently emulsified, but these membranes seem to be different from caseinogen. Measurement of surface tension is a convenient method of quantitative chemical analysis provided that only one substance greatly affecting the surface tension be variable in concentration. It is only necessary to plot the graph of surface tension and con- centration in order to make a table for converting surface tension readings into concentrations. In mixtures, however, the problem may be more difficult. G. D. Allen (1916) measured the surface tension of urine containing different concentrations of bile salts. Bile salts greatly increase the surface tension, but NaCl, which in pure solution slightly raises the surface tension, increases the effect of bile salts in lowering the surface tension. H ions increase the effect and OH ions decrease the effect of bile salts. Sodium taurocho- late is slightly less effective than sodium glycocholate and, hence, a variation in the proportions of the two salts would slightly affect the result. The following table shows the limits of error when the urine is diluted to a specified specific gravity in order ap- proximately to regulate the concentration of NaCl and other interfering substances. Showing the Amounts of Sodium Glycocholate Required to Give Any Observed Surface Tension in a Sample of Urine Diluted to a Standard Sp. Gr. of 1.010. Minimum of sodium gly-/Maximum of sodium gly- S. T. of sample diluted cocholate which may cocholate which may tt 1.010 sp. gr. give observed S. T. give observed S. T. SSS ed (Sample is acid.) (Sample is alkaline.) Per cent of that of dis- Diluted sample. Diluted sample. tilled water. gm. per 100 ce. gm. per I00 ce. 95 oO 0.001 90 oO 0.004. 85 0.001 0.008 80 0.003 0.015 75 0,007 0.03 70 0.015 0.065 65 0.033 o.1+ 60 oI 0.1 OF VITAL PHENOMENA 65 Billard and Bruyant (1905) observed the use made of surface tension by the beetles, Stenus tarsalis and cicendeloides, that dart about on the surface of water. They are pulled forward by the surface tension of the water in front, while the surface tension of the water behind them is decreased by substances discharged from the anus. A model of this may be made by attaching a piece of camphor to one end of a stick floated on water. Traces of the camphor dissolve and lower the surface tension behind, and the stick moves forward. An irregular piece of camphor alone darts about owing to unequal solution on different sides. Adsorption As a rule, substances which lower the tension of the water- air surface also lower the surface tension between water and a solid, but the latter can be measured only in terms of adsorp- tion. Traube gives the following data showing the effect of .25 molecular solutions on the tension of the water-air surface as compared with the amount adsorbed by a unit quantity of animal charcoal. Solute. Surface tension. Adsorption. Acetic acid 84 i244 Ethyl alcohol ; 85 .136 Propionic acid 7575 366 Butyric acid 613 573 i-Amyl alcohol 374 780 It may be seen that surface tension and adsorption are inversely proportional except in the case of acetic acid, which is adsorbed by charcoal more than we would expect from the surface tension of its solution against air. A similar series was obtained of the adsorption of these substances by powdered glass, cotton and silk. The adsorption curve for different concentrations is similar to the surface tension curve, Fig. 24, a larger proportion of the solute being adsorbed from dilute solutions than from more con- centrated solutions. An empirical formula to express this curve x that has been suggested is — = ac!/*, where x is the amount of m substance adsorbed, m is the amount of adsorbent powder, c is the concentration of the solution after equilibrium is established and a and are empirical constants (Freundlich, 1907). N is usually greater than 1 and this makes the equation characteristic 66 PHYSICAL CHEMISTRY for adsorption and surface tension. The equation is not quite correct, however, for concentrated solutions. As the concentra- tion of the solution is increased the surface becomes saturated and will not adsorb any more. Non-electrolytes that reduce the surface tension compete for a place at the surface. The one which is the more effective in reducing the surface tension will displace the other from the surface. The effect of two or more substances on surface tension is additive if the concentration curve is taken into consideration. The same rules hold for adsorption. Electrolytes that reduce surface tension are adsorbed. If the surface be electrically polarized, however, it affects the adsorp- tion of electrolytes but not of non-electrolytes. When this is the case, electrolytes and non-electrolytes that reduce the tension do not displace one another on the surface, but act independently. The adsorbability of anions increases in the order: SO, phos- phate’ > oxalate’> SO,”> I’> Br’> Cl’> NO,’. The ef- fectiveness of the cations in reversing the charge of the membrane and disturbance of neutrality is as follows: Co(NH,),""> La"“i> Ca**> Ba" > Mgi'> Na'> Cs'> Ki> Li’> NH,}. The experiments of Bethe on living cells (1916) are, however, open to another interpretation. It was shown (McClendon, 1914 d) that the anthocyan (or other pigment) in many plant cells is amphoteric. In acid it is red and goes to the cathode, whereas in alkali it is blue or green and goes to the anode, if an electric current is passed through the solution. These changes may be observed in the living cells, which are penetrated easily by acetic acid or ammonia but are easily injured by the reagent or current so that the pigment passes out of them. In successful experiments, all of the pigment is massed in the cathode ends of red cells and in the anode ends of blue cells. When the plant is fresh the pigment is usually reddish, but contains a small pro- portion of blue, and sometimes violet cells may be found. If an electric current is carefully passed through a violet or red- violet cell under the microscope, the red portion of the pigment will mass in the cathode end of the cell, and the blue portion in the anode end. This phenomenon may have led Bethe to suppose that the passage of the current through the membrane disturbed the reaction. His experiments on cells stained with neutral red are not, however, open to this objection. It should be noted that the anode end of the cell is the cathode side of the membrane against which the pigment is massed. It might be supposed that the colloidal membranes used by Bethe and Toropoff are so different from the porcelain used by Bartell that the results may not be compared. Bethe and Toro- poff found, however, that membranes of clay or carbon behaved in the same way as gelatine membranes, in the disturbance of neutrality on the passage of an electric current through them. We may, therefore, safely use the foregoing findings in ex- plaining the results obtained with various membranes, Flusin OF VITAL PHENOMENA Iil (1908) observed that a solution of tartaric acid passes through pig’s bladder into pure water (negative osmose). Evidently the acid reversed the charge on the membrane, making it positive, the greater speed of the positive ion causing the negative osmose. Although Flusin adopts another explanation for anomalous os- mose, Girard (1908-13) shows conclusively that electroendos- mose is at least in part the correct explanation. If the solutions on the two sides of the membrane are isotonic the driving force of osmose is the diffusion potential causing electroendosmose. In the following table the first column gives the solutes used in the isotonic solutions, the second the charge of the membrane, the third column the direction of the emf (positive current), the fourth the direction, and the fifth the relative magnitude of the osmose. Isotonic membrane diffusion direction of magnitude of solutions potential emf osmose osmose Tana, 1 1 33 Pino), + J | ‘9 cor > tbe mor tb With a membrane separating isotonic solutions of NaCl and KCI there was no emf and no osmose. The same was true of KCl and Na,SO,. Although these experiments of Girard ante- date those of Bartell and Hocker, the latter have been described first on account of the simple character of the membranes and the remarkable relation of the diameter of the pores to their properties. Although it may not have been shown that all anomalies in osmose are due to electroendosmose, it seems un- necessary at present to accept the hypothesis of Flusin that osmose takes place through the membrane from the side of least swelling (smaller pores) to the side of greatest swelling (largest pores). At any rate, the size of the pores in porcelain mem- branes is not affected by the character of the solute (Hofmeister series ). ie PHYSICAL CHEMISTRY Bernstein (“Elektrobiologie,” p. 162) supposes electroendosmose to be the explanation of his observations on negative osmose through copper ferrocyanide membranes, although he records no observations on the electric charge of the membranes or the emf. On filling the osmometer with K,FeCy, solution and im- mersing it in CuSO, solution of slightly higher osmotic pressure ‘ (calculated from the freezing point) he observed a rise in the manometer, in some cases overflowing at 34 cm. In order to eliminate any possibility of error from the unequal temperature coefficients for the osmotic pressures of the two solutions, he repeated the experiments at 0°, and yet the manometer over- flowed. The emf of these membranes as measured by Briinings are given below. Comparison of the Polarization of Various Types of Membranes The behavior, mentioned above, of the copper ferrocyanide membrane may seem surprising, because, of all dead membranes that have been investigated, it has proved to be the most truly semipermeable in osmotic experiments. Briinings (1907) using isotonic solutions of CuSO, and K,FeCy, observed that the CuSO, side is electropositive. He supposed the emf to be due to the permeability of the membrane to K ions, and its being im- permeable to the other ions. If this were the case, the emf should be proportional to the logarithm of the concentration of K ions (which is not true, as the emf remained very near 100 mv with large variations of K ion concentration). It has been shown by H. N. Morse (1914) that these membranes rapidly deteriorate when in contact with other ions than those from which they are formed, and for this reason it may be impossible to decide this question. When we remember, however, that Morse observed that the membrane may be greatly thickened by the passage of an electric current, it becomes clear that the membrane cannot be absolutely impermeable to copper and ferrocyanide ions until its electric conductivity becomes practically zero. Evidently, during the formation of the membrane (without the aid of the current) negative charges are removed from the ferrocyanide solution and positive charges are removed from the copper solu- tion, which would produce an emf opposite to that found by Briinings if the membrane is impermeable to all ions except copper and ferrocyanide ions. OF VITAL PHENOMENA 113 According to Beutner (1913, b) copper ferrocyanide mem- branes are permeable only to the cations of many salts. In order to prevent deterioration of the membrane he set up this series: Calomel electrode|K,FeCy,|CuSO,+-x mol. salt|calomel electrode. With n/4o NaCl in the CuSO, solution the emf was 29 milli- volts, and with n/goo NaCl in the CuSO, solution the emf was 80 mv, or a difference of 51 mv produced by diluting the salt ten times, whereas the difference calculated by Nernst’s formula is 58 mv. Taking Beutner’s results as evidence that these membranes are permeable only to the cations of the salts of alkali metals, we may explain the negative osmose observed by Bernstein on the assumption that the membrane is negative, hence the water posi- tive, the diffusion of the K ions leaving the ferrocyanide solution negative. One of the clearest demonstrations of the relation of perme- ability to membrane polarization was shown by Bayliss (1911). He separated two solutions of the sodium salt, congo red, by a membrane of parchment paper. The Na ions can easily pass through the membrane but the congo red anions cannot pass through a dense grade of the paper. Therefore the dilute side is electropositive. Bayliss found the emf, when measured im- mediately after the membrane was wet with the solutions, to approximate that calculated by Nernst’s formula, but to fall gradually. He explained the fall by assuming that the osmotic pressure of the concentrated solution draws water through the membrane, thus forming a dilute layer next to the membrane and lowering the difference in concentration between the solu- tions in immediate contact with the two faces of the membrane. The author found that even with KCl solutions, parchment paper gives an emf, but the potential difference falls very rapidly, so that it is impossible to measure the initial potential with the potentiometer method used. The fall in potential is not entirely due to dilution of the more concentrated solution, since after removing and partially drying the membrane and renewing the solutions, the original potential is not obtained. Since the emf becomes zero after a comparatively short time, the fall is prob- ably due, at least in part, to swelling of the membrane and conse- quent enlargement of the pores. In one experiment an emf of 114 PHYSICAL CHEMISTRY 40 mv was observed. With a wooden membrane and KCI the emf was 7 mv, and the dilute side positive. The emf produced by porcelain membranes in Hocker’s ex- periments was very small, due to the fact that he waited twenty- four hours for equilibrium to occur before making the read- ing. He found that time to be required owing to the thickness of the porcelain. Very irregular results were obtained if the reading were taken soon after filling the apparatus. The author observed that the bowl of a clay pipe showed negative osmose and was thin enough to come to an equilibrium more quickly, provided the previous solution had been thoroughly soaked out of it. Briinings (op. cit.) found Nernst’s formula to be approxi- mated with a burned clay membrane separating n/1oo and n/1000 NaCl solutions, the observed emf being 50 mv and the calculated 59 mv. Briinings obtained rapid equilibrium by soaking the membrane in the more concentrated solution, in one case boiling it in this solution sixteen days with a reflux condenser. Briinings tried membranes of burned clay, wood, bone, carbon and marble with NaC} and KCl, and in every case the dilute side was posi- tive. Since the Cl ion is faster than the Na or K ion these mem- branes must be more permeable to cations than to anions. Probably this is due to repulsion of the anions by the negative charge of the membrane. The effect of the electric charge of the membrane on its rela- tive permeability to anions and cations is illustrated by an experi- ment of Mines’ (1911 b). In the following concentration cell the emf is zero: Zn, ZnSO, | n/8 NaCl| n/80 NaCl |n/8 NaCl | ZnSO,, Zn. If, however, a gelatine membrane is placed between two of the NaCl solutions the dilute side becomes positive with an emf of about 60 my. The gelatine, therefore, is more permeable to cations than to anions, and it is well known that natural gelatine is electronegative. Gelatine is made positive by the ions of polyvalent metals, and hence Mines treated the gelatine with a salt of Gadolinium to test its effect on the emf. The same gelatine membrane used above, after treatment with GdCl, and being returned to the concentration cell, caused an emf of 8 mv, but the dilute side was negative, showing that the membrane had OF VITAL PHENOMENA 115 become more permeable to anions or less permeable to cations —perhaps both. Selective permeability of membranes to ions has often been noticed in electrical transference experiments. Hittorff separated the solution between the electrodes into segments by means of ox gut membranes, in order to prevent backward diffusion or convection currents. He supposed the membrane did not affect the results (transference numbers), but it is now known that the effect is small in some cases, very large in others. Bein (1899) found that earthenware membranes were the safest to use. Fish bladder membranes caused but small errors with neu- - tral salts of alkali metals, but large errors with CuSO, solutions. The SO, ions passed the membrane, but the Cu ions combined with the substance of the membrane, and hence were held back. The action of gelatine membranes in holding back H ions in a similar manner has been noticed ‘by Girard and by Cybulski (1903) and Cybulski and Dunin-Borokowski (1909). Where the membrane clearly forms a separate phase the elec- tric phenomena have been called by Nernst and Riesenfeld (1902) phase boundary forces. If the speed of the ions in two phases is different, the addition of the electrolyte to either phase will cause a difference of potential at the phase boundary, which is different from that which occurs in a similar concentration gradient in either phase alone. The limiting case is that in which the speed of either ion becomes zero (in the membrane). Such is the case with a metallic membrane, which may be considered impermeable to any ion except the cation of the same metal. Although the atom and its electron part company in passing through the membrane, and the ion as such does not pass through, the effect is the same, since an ion is given off from one side at the instant that an identical ion is deposited on the opposite side of the membrane. It seems proper, therefore, to speak of the permeability of a metallic membrane to an ion, when the mechanism of the passage of the ion or its components through the membrane is of no significance to the point of discussion. When an electrolyte dissociates into two ions to only one of which the membrane is permeable, the emf may be calculated by Nernst’s formula for electrode potentials. The emf is 59 mv 116 PHYSICAL CHEMISTRY at 25°, when this ion is monovalent and is ten times as concen- trated on one side of the membrane than on the other. It is characteristic of most of the separate phase membranes that have so far been studied that they are very poorly permeable to water. Their ionizing power is often very small, and except- ing the metallic membranes, they are poor electric conductors. Hence the measurement of the emf with a galvanometer, capil- lary electrometer, or even a potentiometer, is sometimes im- possible. A quadrant electrometer of Lord Kelvin’s or Dole- zalek’s type is usually used. For the general case of a membrane permeable to both ions of the solute, Nernst’s ideal formula in millivolts at 25° is, u—v ss u’—-v’ Cy utv w’-+v’ Cy where wu and wv are the speeds of cation and anion in water and uw’ and v’ in the membrane. Though the emf so calculated would be correct if the two aqueous solutions were connected so as to form a closed circuit, the emf could not be measured under such conditions. If calomel electrodes are used, the solutions con- necting this concentration chain to the electrodes would have an effect on the total emf as measured. Examples of membranes permeable to only one of the two ions of an electrolyte are given by Cremer (1906) and Haber and Klemensiewicz (1909). Membranes of ice, benzol, toluol, metaxylol, nitrophenol, and thin, water soaked glass, acted as. though they were permeable only to H ions. When the H ion concentration on one side of the membrane was ten times as great as on the other side, the average emf with soft glass was 52 mv and with hard glass 59 mv, whereas that calculated from Nernst’s formula is 58 mv at 20°. The emf with the other mem- branes was almost as great. Haber and Klemensiewicz used almost pure solutions of acids and bases (without buffers) and, in their tables, did not correct for dissociation. Furthermore, they made no accurate measurements near the neutral point. Since the reaction of all living cells or fluids bathing them is near the neutral point, it seemed worth while to make such de- terminations, in order to ascertain whether such membranes emf = 59 ( OF VITAL PHENOMENA 117 might account for the bioelectric phenomena. Prof. A. F. Kovarik kindly took the readings with an improved Dolezalek’s electrometer. Benzol was used as a membrane. Its conductivity is so low that the concentration cell had to be enclosed in a metal cage before constant results were obtained. The H ion solutions were PH = 6 and 7 made with the aid of Sérensen’s phosphate mixtures and tested with the hydrogen electrode. The emf was 31 mv, whereas the theoretical is 59 mv. This is not, however, a greater discrepancy than in some of Haber and Klemensiewicz’s experiments with benzol, the potential difference between n/Io and n/1oo HC! being only 18 mv. The emf of living muscle as measured, is not usually greater than 31 mv, and since the PH of the blood is about 7.5 the reaction of the muscle contents need only be PH = 6.5. Whereas, in the above membranes, their chemical nature seemed unimportant, ice, glass and carbocyclic compounds be- having in the same manner, the permeability of certain other membranes depends, according to Beutner (1913 d), on a chem- ical reaction. Beutner used one series of membranes permeable only to cations and another only to anions. An example of the first class is salicylic aldehyde, that on oxidation formed traces of salicylic acid. If such a membrane separates solutions of the same salt of different concentrations, the dilute side becomes negative. If both solutions are very dilute, Nernst’s formula may be used to calculate the emf approximately. According to Beutner the cations pass through the membrane by being trans- formed into salicylates, which are soluble in salicylic aldehyde. Beutner’s experiments were repeated with n/1oo and n/1000 KCl on the two sides of the membrane, and an emf = 36 mv obtained on Prof. Kovarik’s electrometer. The conductivity of the salicylic membrane is too low to use the potentiometer if the ordinary U-tube is used in making the concentration cell, but at least qualitative results were obtained in the following manner: A solution of CaCl, of greater specific gravity than the aldehyde was placed in the bottom of a beaker and a glass tube introduced into it. A layer of salicylic aldehyde (to which some salicylic acid had been added to increase its conductivity) was floated on top of the CaCl, solution, and a dilute solution of CaCl, added as a third story. In this way 118 PHYSICAL CHEMISTRY a membrane of larger surface and less thickness was made. On connecting one calomel electrode with the dilute solution and the other through the glass tube with the concentrated solution, an emf of 25 mv was measured with the potentiometer, the dilute side being positive. The other type of membrane is an organic base, which, accord- ing to Beutner, combines with the anion of the electrolyte to form a salt soluble in the membrane. His experiment was re- peated with o-toluidin, in the same manner as with salicylic aldehyde, and obtained 27 mv with the Dolezalek electrometer. In order to use the potentiometer, chloroform was added to the toluidin to make it heavier, and 80 mv obtained, the dilute side being negative. In order to obtain larger membranes, parchment paper tubes were soaked in salicylic aldehyde, toluidin or anilin.. In each case the emf was what would be expected with parchment paper alone, but was maintained for a longer time. For this reason it seems possible that the organic liquid was effective in retard- ing the wetting of the paper with consequent enlargement of its pores. If this is true it shows a method of finding the initial emf with parchment paper. Although with toluidin alone the dilute side is negative, when it is applied to parchment paper the dilute side is positive. The emf with n/1oo and n/1ooo KCl was 59 mv, and substituting toluidin, was 52 mv. According to Loeb and Beutner (1913) a solution of lecithin in m-cresol acts in the same way as salicyl aldehyde when used as a membrane in a concentration cell. But since higher fatty acids could be substituted for lecithin, it seems probable that fatty, or glycerophosphoric acid, formed by the decomposition of lecithin was the active agent. Bioelectric Phenomena The electromotive forces produced by living matter have al- ways been a subject of interest, if not amazement. The shock of some electric fish is several hundred volts, and may be felt while the fish is entirely submerged in sea water. On the other hand, the ordinary electric potential differences observed in living matter never reach 0.1 volt. The secret of the electric organ lies in the connection of the elements in series. Briinings ob- OF VITAL PHENOMENA 119 served that if one frog’s skin is laid on another, the emf is doubled. In the same way he found the emf of two concentra- tion cells with porcelain membranes to be doubled when they were connected in series. The principle is the same as that of the voltaic pile, and only the nature of the membrane is different. A dissection of an electric organ reveals the serial arrangement, and also (in all electric organs related to muscle tissue) that the side of each element on which the nerve enters is electro- negative (Pacini). It seems probable that the manner of pro- duction of electricity is the same in the electric organ as in muscle or nerve or any sensitive cell. We shall therefore proceed to discuss the general question of the exhibition of electromotive force by the cell. The electromotive force of a single cell was observed by Hyde (1904). She placed one non-polarizable electrode on the animal pole and one on the vegetative pole of the egg cell of a fish. When the cell began to divide the animal pole became negative. Owing to the small size of most cells, it is usually more con- venient to study these phenomena in tissues in which similar cells are arranged in multiple. The frog’s muscle is convenient. It is possible to measure the difference in potential between the inside and outside of the cells by cutting off one end of the muscle and leading off from the cut surface (interior) and the intact surface (exterior). The interior is found to be negative in comparison to the exterior, which causes an electric current to flow through any external conductor that may be present from the intact to the cut surface. This current is often called the current of injury, without any proof that the injury, as such, has anything to do with it, but the expression is convenient. Wilhelm Ostwald suggested that the muscle is a concentration cell with a membrane, and Bernstein developed the details of this idea. No one doubts that the muscle is a concentration cell, but the opponents of Bernstein’s hypothesis doubt that a membrane has anything to do with it, since concentration cells may be made without membranes. But the emf of the current of injury of a fresh muscle is from 40 to 80 mv and no concentration cell with- out a membrane has been known to give such a high emf unless it contained strong acids or alkalis, which are incompatible with life. There seems to be no valid evidence against, and much for, 120 PHYSICAL CHEMISTRY Bernstein’s theory. Furthermore, it is the only theory that will account for all of the facts. According to Bernstein, the striated muscle fiber or cell is surrounded by a membrane or surface (called the plasma mem- brane since it is the superficial layer of the protoplasm), which is more permeable to the cation than to the anion of some elec- trolyte more concentrated in the interior than on the exterior of the muscle cell. The cations passing through the plasma mem- brane leave the interior negative, and form a positive outer stratum of an electric double layer thus formed at the surface of the cell. Many attempts to determine the electrolyte have been indecisive, but it seems probable that the cation in question is the. hydrogen ion, in which case the cell surface must be rela- tively impermeable to all anions. This assumption has the ad- vantage that it avoids the necessity of difference in osmotic pressure on the two sides of the membrane. A diagram of this ttet ttt eet t +-8-@O--+-- SO+ 474 4 47% + + te tetert * Fic. 28. Scheme showing the plasma membrane of a cell torn open at one end and liberating the excess of anions. The + and — indicate the charge of ions and the arrows the direction of diffusion. Only + ions can come out through the intact plasma membrane and hence there is an excess of — ions on the interior. The tear causes a negative charge to appear at the surface and give rise to the current of injury. idea is shown in Fig. 28, representing a muscle cell with one end cut off to produce the current of injury. The (—) signs are anions that can escape only at the cut end. The current of injury is caused by the escape of the anions at the cut surface. What these anions may be is immaterial, but presumably they include proteids with negative charges and anions of carbonic and lactic acids produced in the muscle fiber. The acidity within the cell necessary to produce such an emf as in muscle need be only that of a molecular solution of CO,. OF VITAL PHENOMENA 121 The H ion concentration of the blood at 20° is about PH = 7.5 and with such a reaction outside the cell and PH = 6.5 inside the cell, the theoretical current of injury would be 58 millivolts, which is about the average value actually found. With the model mem- brane given in the first section, the emf did not reach this theo- retical value, but it is reached in the average of one series of determinations by Haber and Klemensiewicz. Not only is the cut surface of a muscle negative, but the region of a muscle that is stimulated becomes negative for a fraction of a second. The current produced by this negativity is called the action current, and since the current of injury is produced by the removal of the resistance to diffusion at the cut surface, the action current is probably due to a momentary increase in permeability at the stimulated surface. If this is true we should be able to increase the electric conductivity of muscle momentarily, by stimulating all of the fibers simultaneously. Since it is not easy to measure conductivity in a few thousandths of a second, even with a string galvanometer on stimulating the nerve, another method of stimu- lation was adopted (McClendon, 1912 c). The conductivity of a resting muscle was measured by passing an alternating cur- rent transversely through it. By putting in resistance this cur- rent was made too weak to stimulate the muscle. After the conductivity was determined, the resistance was short circuited and the conductivity determined while the muscle was thrown into tetanus by the alternating current, and found increased from 6 to 28 per cent. It has been objected that the action current of the muscle reinforced the alternating current, but the contrary is true. The muscle is stimulated on the side of the momentary cathode, and the stimulated region, becoming nega- tive, opposes a cathode to a cathode, hence opposes the current. It is also stated that the change in form of the muscle fibres in- creases the cross section of the interfibrillar spaces. This ob- jection seems to have no theoretical basis. If a vessel is filled with small spheres the cross section of the space between the spheres is the same as though it were filled with large spheres. In my experiments a relatively large muscle was pressed between two platinized platinum discs as electrodes. Between the discs were a large number of cylinders (fibers) and when the muscle 122 PHYSICAL CHEMISTRY contracted it was drawn in at the ends and pushed out at the sides, so that the same area lay between the electrodes, but was now composed of a smaller number of larger cylinders. It may be objected that the surface of the contracted fibers is thrown into waves but this does not affect the problem, because such fibers can be resolved into an infinite number of short cylinders of different sizes placed one on another. If a change in the diameter of all of the fibers does not affect the conductivity, a local variation in the diameter of one fiber does not affect it. It seems that the evidence points to an increase in the permeabil- ity of the muscle on stimulation. It was shown by Kunkel (1887) and Burdon-Sanderson (1888) that an action current follows stimulation of the sensitive plant, Dionea, and the same has been found true of a host of plants by A. D. Waller. It seems probable that an action cur- rent (blaze current) follows stimulation of any plant except perhaps most marine plants, as indicated by Waller. This increase in permeability may cause movements (in addi- tion to electric phenomena). Pfeffer (“Physiol. Untersuchungen” - 1 and 2, 1873) studied the movements of plants. The stiffness of a plant is due to the pressure or turgor within its cells, and Pfeffer observed that plant movements are caused by local varia- tions of turgor. Each cell is surrounded by a semipermeable plasma membrane. The osmotic pressure within the cell causes the absorption of water, from the capillary spaces between the cells. When the plant is stimulated certain cells lose their semi- permeability and the cell sap filters out into the intercellular spaces, causing a local shrinkage of the tissue. Waller (1904) observed that the conductivity of plants may increase 100 fold (or less) on stimulation, thus giving more evi- dence for permeability increase. He observed the blaze current to last fifteen minutes in some cases, which makes it easier to study conductivity during the stimulated state. Whereas the action of the sensitive plant may reach a maxi- mum one second after stimulation, movement does not begin until two and one-half seconds after stimulation. The time re- quired for diffusion together with the mechanical inertia of the parts probably accounts for the delay. We may sum up the data on the universality of the bioelectric OF VITAL PHENOMENA 123 phenomena by saying that the current of injury has been ob- served in all living tissue where it has been looked for, but that action currents have been observed in the leaves of land and fresh water plants, and in animal nerve (and retina), muscle .and glands and electric organs derived from them, as well as in the eggs of fish. These electric phenomena are due to changes in permeability to ions. The excited state (increased permeabil- ity) remains but a few thousandths of a second in muscle or nerve but may remain fifteen minutes in plants. The most wonderful thing about the electrical variation of muscle, nerve or sensitive plant is that it is self propagated. The results of study of electrical stimulation have made the self propagation of the electrical variation a necessary consequence of excitability. It is probably the negative variation of nerve that stimulates another nerve or the motor end plate of the muscle. The medullated nerve fiber is surrounded by an insu- lating sheath, broken only at the occasional nodes of Ranvier. When a minimal current is sent through a medullated nerve cross- wise no stimulation takes place, apparently because of the insula- tion of the fibers. But when it is sent lengthwise through the nerve it may enter at one node and leave the fiber at another. (The author found non-medullated nerves of Limulus to be as sensitive to a current sent crosswise as to a longitudinal current.) The nerve is stimulated nearest the cathode or apparently where the current leaves the fibers at the nodes nearest the cathode. In other words, the approach of a cathode to the plasma membrane stimulates the nerve fiber. But the stimulated region becomes electronegative and hence a little cathode. It stimulates regions adjacent to it, and the stimulated area spreads like a fire. The reason for this can only be learned when we discover the cause of the increase in permeability of the plasma membrane. H. N. Morse (1914) states that copper ferrocyanide membranes are colloidal and that a crystallization, resulting in increase of the size of the particles, increases the permeability of the membrane. But the size of colloidal particles may be considerably increased without crystallization (by electrical disturbances). Perhaps the plasma membrane is colloidal and the sudden electrical disturb- ance, due to the approach of a cathode, causes the particles to aggregate into groups. If the plasma membrane is composed of 124 PHYSICAL CHEMISTRY ; negative colloids like the rest of the cell, the approach of a cathode would tend to lessen the charge on the particles and induce aggregation. The negative charge of cell colloids is illus- trated by the author’s experiments in passing a constant current through plant (McClendon, 1910, b) and animal (McClendon, 1914, d) cells. Chromosomes, yolk granules, and protoplasm in general pass toward the anode, whereas water passes toward the cathode and forms a blister on some animal cells. If the plasma membrane is composed of the same colloids as the cell interior it is probably negative. It may be objected that these colloids become positive in an-acid medium and that this nega- tivity is incompatible with the assumed acidity of cell interiors. But the isoelectric point of most of these colloids is much farther on the acid side than the reaction we have assumed for the in- terior. Furthermore, the plasma membrane is nearer the blood which is alkaline, and is probably bathed by an alkaline tissue juice. The cell sap in the cells of red flowers has an acid re- action. The rate of propagation of the excitatory impulse may be I mm per second in some plants and 12000 in mammals. It is probably very slow over the bodies of nerve cells and motor end plates, as there is some delay in conduction through these regions. Mayer (1916) found that nerve conduction varies almost as the concentration of electrolytes around the nerve. Lillie (1916 b) supposed nerve conduction to vaty with electric conductivity but Mayer has not observed an exact parallel. Since glands are the seat of an emf, and the skin contains glands, the skin is the seat of an emf which varies with glandular activity. If a. constant electric current is passed through the body, the electrical resistance is found to be high. If a gal- vanometer is interposed in the circuit, the needle may soon come to a constant deflection, but if the subject becomes mentally ex- cited, as on hearing bad news, the galvanometer deflection is suddenly increased. This is called the psychogalvanic reflex, and is used by clinicians and psychologists in the examination of the reactivity of persons. Gildemeister (1915) in a very elaborate and carefully controlled series of experiments, showed that the psychogalvanic reflex is due to increased permeability of the sweat glands, which have been stimulated through sym- pathetic nerves. OF VITAL PHENOMENA 125 The emf of the frog’s skin has been the object of many in- vestigations, but the results so far are for the most part con- fusing. Schwartz (1915) found that the electrical conductivity of the frog’s skin is increased when the nerves to the skin glands . are stimulated. It is probable that the emf of the frog’s skin is analogous to the action current, or more nearly to the current of injury of muscle, and is due to the permeability of one side of the gland cell and semipermeability of the other, the latter being the seat of the emf. The experiments of Bayliss (1908) tend to support this view. On passing an alternating current through the frog’s skin, he observed that it acted to a certain extent as an electric rectifier, allowing a current to pass more easily in one direction than in the other. The same effect was produced by a parchment paper membrane separating a solution of congo red from water. This dye dissociates into Na ions and enormous anions. If the cathode is placed in the water, the current is carried through the membrane by the Na ions, but if the anode is placed in the water, the anions attempt to pass through the membrane to the anode, but are unable to do so. Perhaps much of the confusion arising from the study of the emf of living tissues is due to the fact that they are made of more than one kind of cell, and that the permeability of the cells may be changed by the experimental procedure. Consider, for example, the excised muscle. If it is bathed on all sides by lymph or blood, any emf observed is probably due to the muscle cells, but if one electrode is connected to it by a more concen- trated solution and the other by a dilute solution of electrolytes, the system may form a concentration cell in which the peri- mysium or muscle sheath is the chief membrane concerned. The fact that porcelain membranes may act in this capacity, shows that relatively permeable membranes must be taken into con- sideration, even membranes allowing an appreciable amount of filtration. Oker-Blom (1901) studied what he called the contact potential between muscle and certain solutions. This work was extended by Brinings (1907) who attempted to prevent the in- jurious effect of diluting the salt solutions by the addition of sugar to make them isotonic. He found the contact potential between frog’s muscle and sugar solution to be 50 millivolts, with the sugar side positive, and the same result was obtained with 126 PHYSICAL CHEMISTRY dead muscle. Perhaps the perimysium surrounding the muscle, being formed of electronegative colloids, is more permeable to the cations than to the anions of the electrolytes between the muscle fibers, hence the dilute side (in reference to the salt) is positive. When the end of a muscle is dipped in water, the dilute (water) side is positive until the water injures the muscle, when the dilute side becomes negative, the perimysium emf being superseded by the current of injury. Briinings found that when the entire body of a man, a frog or a plant is used as a mem- brane in a concentration cell, the dilute side is positive. Loeb and Beutner (1914), who extended Brtinings’s experi- ments, oppose all hypotheses on the origin of animal electricity which relate to membrane destruction or selective permeability to ions. They admit, however, that a current of injury is pro- duced by cutting off part of the skin of an apple, and that the same increase in permeability may be produced by merely press- ing the skin with the finger. The argument they bring against Bernstein’s hypothesis is the similarity between living tissue on the one hand and Beutner’s acid membranes or lecithin in guaicol on the other, when used as membranes in certain concentration cells. It seems perhaps more significant that in a previous paper (1912) they interpret their results as showing that the seat of the current of injury is the intact membrane and that it is caused by the increase in permeability or removal of the membrane at the injury. Having thus sketched the membrane hypothesis, it may be ad- visable to add additional proofs of its validity. If the membrane theory is correct, change of temperature of the cut end of a muscle should not affect the current of injury since the cut end is not the seat of the emf, but the current of injury should be proportional to the temperature of the intact end. From Nernst’s c formula emf (in millivolts) = .198 T log as where T is the Co absolute temperature, hence any change in T would cause a corresponding change in the emf. Bernstein (“Elektrobiologie,” p. 97) found this to be the case, at least between the tempera- tures 18°-0°. In case two points on an intact muscle are at different temperatures Nernst’s formula becomes emf = .198 T, OF VITAL PHENOMENA 127 —.198 T,, which means that a thermocurrent will be produced proportional to the difference in absolute temperature. Bern- stein found this to be true also, the warmer end being positive. Further proof of functional change in permeability of the plasma membrane to electrolytes was found on measuring the conductivity of sea urchin eggs by the Kohlrausch method. The conductivity increases when the eggs are stimulated to begin development (McClendon, 1910 c, e). This was confirmed by Gray (1913, a, b) who observed an increased conductivity in the first fifteen minutes of development. Just what electrolytes were _ affected by this increase in permeability was not ascertained, but in case of the frog’s egg, the author was able to show an in- creased permeability during the first hours of development to Na, K, Mg, Ca, and Cl (1914 a, 1915 a). The eggs were caused to develop in distilled water by means of electric stimulation, and the salts which diffused out analyzed and compared with those diffusing out of unstimulated controls. A change in permeability may also accompany pathological changes. It was shown (McClendon, 1913 a, 1914 c) that the eggs of certain fish which are impermeable both to water and to salts, may be made permeable to salts by various toxic sub- stances. Salts diffuse out of these poisoned fish into the distilled water in which they are placed, and (possibly as a result of in- creased permeability) they develop into monstrosities. An in- crease in permeability to water was shown by Loeb (1912 b). If stimulation means increase in permeability, we should ex- pect anesthetics to prevent it, since they prevent response to stimuli. It was observed that the increase in permeability of the eggs of certain fish to electrolytes could be partially inhibited by ether (McClendon, 1914 b, 1915 b). Since Kite claims that the interior of the cell has the same permeability as the surface, it is probably worth while to empha- size that the effect of temperature change on the emf of the current of injury furnishes evidence that the seat of restricted permeability is the uninjured cell surface. Furthermore, Hober (1910 a, 1912 b, 1913 b) has shown that the electric conductivity of the interior of the cell is greater than that of the whole cell, including the plasma membrane. 128 PHYSICAL CHEMISTRY Stimulation Modern theories of electrical stimulation depend on membrane polarization. Nernst accidentally passed through his body a high frequency Tesla current of enormous voltage, such as is used in wireless telegraphy, and observed no stimulation. This led him to formulate his theory of electric stimulation, according to which the current must carry a certain number of coulombs of electricity per unit cross section, before it is reversed, in order to stimulate. In other words, stimulation is due to polarization of membranes, and the polarization must reach a certain minimal value. From this it is evident that the higher the frequency of an alternating current (the shorter the time the current flows continuously in one direction) the greater the amperage required in order to stimulate. Using sine wave alternating currents, this was found to be true within certain limits of frequency, but it appeared im- possible to stimulate if frequency reached 100,000 per second. Nernst and Barrat (1904) found that the current required to stimulate = .079 X the square root of the frequency. In order to extend the limits of frequency complicated formulae have been developed to include accessory factors, such as backward diffusion of ions (A. V. Hill, 1910). According to Bethe (1916) the facts fit better the hypothesis that only H ions are concerned in the stimulation. He had found that the passage of a current through a membrane causes the accumulation of H ions on one side and OH ions on the other and supposes that the accumula- tion of H ions on the outer surface of the plasma membrane causes stimulation. He says that the bare nerve fibers exposed at the cut end of a nerve, or which have grown out of the end on regeneration, can be stimulated by acid that is not hyper- tonic, and hence does not stimulate osmotically. The relation of ions to irritability has been much studied, but the problem has not been entirely cleared up. An ion may have one effect at a certain concentration and a different effect at an- other. K ions are said to depress irritability, but according to Beccari (1915) they increase irritability, when applied within physiological limits to skeletal muscle. It is well known that Na increases and Ca decreases irritability. But irritability is lost in the pure solution of any salt. If muscle is placed in isotonic OF VITAL PHENOMENA 129 solutions of the chloride of an alkali metal the irritability dis- appears least rapidly in NaCl and most rapidly in KCl according to the series: Na
  • Ss ——s__ 25 The above solutions may be made nutritive by the addition of -I-.25 per cent glucose. ‘Many green plants will live in distilled water and need no especially protective solution except that any ion if in very high concentration must be made harmless by the presence of some antagonistic ion. Knop’s solution is protective and nutritive for green plants. It is made by dissolving the following numbers of grams in 3-7 liters of water: 4 Ca(NO,),, 1 KNO,, 1 KH,PO,, 0.5 KCl, 1 (MgSO,-7H,O). It is probable that traces of impurities in this solution are essential since many plants contain additional elements. The analyses of Jost on the ash of a number of land plants show them to contain the fol- lowing minerals, beginning with the most abundant: CaHPO,, K, Mg, Mn, Na,SO,, Si, Cl, Fe. The P and S entered at least partly into the composition of proteins, but since anions are necessary to combine with the cations, the salts were probably phosphates, sulphates, chlorides and carbonates. According to Stoklasa (1908) the ash of Azobacter is almost pure K,HPO,. Ad. Mayer (1902) used the following solution for the growth of yeast, expressed as grams dissolved in two liters: 1 KH,PO,, 0.1 Ca, (PO,)., 1 MgSO,. Salts of As, ‘Cr, Zn, Cd, Ni, Co, Cu, Hg, Au and Pt are said to stimulate the growth and fermentative activity of certain fungi, when in certain minute concentrations. These salts are probably to be considered protective (affecting permeability), since the heavy metal ions are powerful antagonists to some more common cations, and only this antagonistic action explains the necessity of exactly limiting the concentration of the heavy metal. Bacteriological media are too numerous to be considered here. The PH is very important (see papers of W. M. Clark). APPENDIX CHEMICAL SUMMARY The elements contained in every living cell are as follows: Element Symbol Atomic weight Valence Hydrogen H 1.008 I ‘Carbon Cc 12 4 Nitrogen N 14.01 3, or 5, or 4 Oxygen O 16 2 4 (6 or 12?) Phosphorus P 31.04 3 5 Sulphur S 32.07 2, 4,6 ‘Chlorine Cl 35.46 I (2, 3, 4, 5?) Sodium Na 23 I Potassium K 39.1 I Magnesium Mg 24.32 2 ‘Calcium Ca 40.07 2 Tron Fe 55.84 3 2 Other elements sometimes present are as follows: Element Symbol Atomic weight Valence Fluorine F’ 19 I Bromine Br 79.92 I+ (2, 3,4,5?) Todine I 126.92 I Aluminium Al 27.1 3 Silicon Si 28.3 4 Manganese Mn 54.93 3, 27 Copper Cu 63.57 2ori1 None of these elements exist as simple atoms in the cell. The chief compound is water, HOH. It seems probable, from the high surface ten- sion, specific heat and dielectric constant of water, that some molecules have combined (polymerized) to form (HOH):s. It is even believed that some of these aggregates are colloidal particles, and cause the blue color of the sea, but it seems more probable that this blue light is dispersed by water molecules, as the blue sky is produced by dust particles on drops of water in the air. Gases dissolve in water in the form of O,, N, or H, Many of the elements exist in solution as salts, formed by the combination of an acid and a base. Na, K, Mg, ‘Ca, Al, Mn and Fe combine with O, forming oxides, which combine with water forming hydroxides, which are bases. F, Cl, Br and I combine with H to form acids and Si, P, S, C, N and O may enter into the composition of acids. The compounds of carbon are so complex and numerous as to form a special group, organic compounds,. This is subdivided into the open chain or aliphatic series and the ring compounds or aromatic series. The paraffins are compounds of carbon and hydrogen in open chain. Starting with methane, CH,, a combination of two molecules gives ethane, C,H,, because two hydrogen atoms are eliminated and the valences thus CHEMICAL SUMMARY 189 freed are used to connect the two carbon atoms. In a similar way pro- pane, ‘C,H,, and butane, C,H,, and an indefinite number of higher com- pounds are formed. In the paraffins all of the valences of the carbon atoms are filled and no more hydrogen atoms can be attached to the molecule without splitting it between two carbon atoms, and therefore these compounds are said to be saturated. In the unsaturated hydrocarbons, however, more hydro- gen atoms may be attached without splitting the molecule, which is thereby converted into a saturated compound. There are no free valences in the unsaturated compounds but two carbon atoms are united by more than one bond, and by opening up one bond two free valences are formed for the attachment of two hydrogen atoms. Thus in ethylene, ‘C.H,, there is a double bond between the carbon atoms and acetylene, C.H,, there is a triple bond between the two carbon atoms. The first products of the oxidation of the paraffines are the alcohols, methyl alcohol, CH,OH, ethyl alcohol, C,H,OH, propyl alcohol, C;H:OH, and so on. Alcohols may combine with bases, but where water is formed by the combination the compound may decompose again. If the presence of water be eliminated the compound is relatively stable. Thus when metallic sodium is dropped into ethyl alcohol, sodium ethylate is formed with the evolution of hydrogen. C.H,OH + Na = C.H,ONa + H and 2H = H.. The combination of an alcohol with an acid forms an ester, thus: C.H,OH + H,SO, = C.H;HSO, + H.O. If an ester is warmed with a strong base, the base combines with the acid and the alcohol is set free, a process known as saponification, thus: C,H;,HSO, + Ca(OH), = C,H,OH + CaSO, + HO. The alcohols with one OH group, like the ones given above, are called monatomic. The highest monatomic alcohol found in cells is cholesterol, ‘C,,H,,OH, a waxy substance, insoluble in water and crystallizing in plates. Alcohols with three OH groups are called triatomic. The one found in cells is glycerol, C;H;(OH);, which is soluble in water, and its esters with fatty acids are called fats. By oxidation of alcohols we obtain aldehydes. Methyl alcohol gives form-aldehyde, thus: 2CH,OH + O, = 2HCHO + H,O. In the alde- hyde group, CHO, the oxygen is united with the carbon by a double bond, which makes the aldehyde capable of further oxidation, in fact it has such an affinity for oxygen as to be a mild reducing agent. The product of such an oxidation of an aldehyde is a fatty acid and the aldehyde is named for the acid that it forms and not for the alcohol from which it is formed, where there is a different name for the alcohol and acid. Thus we have methyl alcohol, formaldehyde and formic acid and we have ethyl alcohol, acetaldehyde and acetic acid, but propyl alcohol, propyl- aldehyde and propionic acid. The CHO group of the aldehyde contains the terminal carbon atom of the chain. If an intermediate carbon atom of the chain bears the double bond we have a CO: group, and the substance is called a ketone. Thus, CH,CH;CHO is propyl aldehyde, but CH,COCH, is dimethyl ke- tone (acetone). The carbohydrates are aldehydes or ketones of polyatomic alcohols, in which the hydrogen and oxygen are usually in the proportion to form water. Aldehydes have a tendency to polymerize or combine to form larger molecules. Formaldehyde in alkaline solution polymerizes to form a series of sugars with six carbon atoms. This seems also to be the mode of formation of sugar in the green plant. The carbonic acid, H,CO,, is reduced by the action of sunlight and the fluorescent chlorophyll to HCHO, the oxygen removed from the carbonic acid combines with 190 APPENDIX water to form hydrogen peroxide, which is immediately decomposed by the catalase of the cell with the liberation of O, The formaldehyde would destroy the cell if it were not immediately polymerized by the action of the green bodies, chloroplasts. The most important sugars are the hexoses or those with six carbon atoms, which are asymmetrical. The carbon atom has four valences and if a different kind of atom or group is attached to each of these valences, the molecule is asymmetrical, that is to say, no point, line or plane of symmetry exists. It is then possible to arrange the groups around the carbon atom in two different ways so that one form of molecule will be the mirrored image of the other. Such asymmetry can be detected be- cause a molecule containing one asymmetric carbon atom rotates the plane of polarized light to the right or the left. If a molecule contains. two asymmetric carbon atoms, both atoms may rotate in the same direction or in opposite directions, and if the rotation is equal in opposite directions the molecule appears inactive to polarized light. There are often obtained mixtures of equal numbers of dextro-rotatory and laevo-rotatory mole- cules, the mixture does not affect polarized light and is called racemic. The hexoses that are readily assimilable by mammalian cells are: lee en st ‘CH,OH ete ae a ig H aka H a oe ae ee ee age ines gy sae see ise ‘CH,OH CH,OH CH.OH CH,OH d-glucose d-mannose d-galactose d-fructose (dextrose (aevulose) This is the nomenclature of Fischer, based on structural formulae. All of these sugars are aldehydes (aldoses) and rotate polarized light to the right, except d-fructose (a ketose) which is usually called laevulose be- cause it rotates polarized light to the left. ' ‘On the oxidation of 1 g. glucose about 3.74 calories of heat are pro- uced. ‘Glucose, fructose and galactose, when reduced, are converted into the alcohols, sorbite, mannite and dulcite. Glucose on mild oxidation, yields gluconic acid, with the COOH group formed from the CHO group. On further oxidation another COOH group is formed on the other end of the chain, and thus the dibasic acid, saccharic acid is formed. Glucose, as well as other hexoses, is easily transformed into lactic acid without oxidation. One molecule of glucose yields two molecules of lactic acid, CH;CHOHCOOH, when acted on by lime in sunlight or by bacteria, or other living cells. As aldehydes or ketones, the hexoses are reducing substances, but this property may be lessened spontaneously, in solution, by what is called lactone formation. In this, the double bond between one carbon and oxygen atom, to which the reducing character is due, opens out and one bond becomes applied to a distant carbon atom in exchange for an OH group. ‘Glucose may combine with other substances, forming glucosides. This combination is usually preceded by lactone formation. Tiwo hexose mole- cules may combine by the opening out of a double bond and the elimina- tion of one molecule of water, forming a disaccharide molecule. Thus CHEMICAL SUMMARY I9I glucose and glucose form maltose, glucose and galactose form lactose, and glucose and fructose form saccharose or cane sugar. One gram of a disaccharide on oxidation produces 3.95 calories of heat. Pentoses, with five carbon atoms, are found in many plant cells. Polysaccharides are formed by the combination of simple sugar mole- cules. Gums, pectens and mucilages are formed of monosaccharides, and starch, dextrin, glycogen and cellulose are formed of glucose. The mo- lecular weight of starch is estimated at between 1260 and 32400. Its osmotic pressure is so small that it appears to be zero. By the oxidation of the CHO group of the aldehydes the COOH group of the organic acids is obtained. The open chain acids are called fatty acids and bear the same name as the aldehydes from which they are formed. In the series, formic, acetic, propionic, butyric, valerianic and caproic, each member has one more carbon atom than the one preceding. The fatty acids most common in animal cells have even numbers of C atoms. These acids are butyric, caproic, caprylic, capric, lauric, myris- tic, palmitic and stearic. The solubilities of these acids in water decrease as the number of carbon atoms increases, the higher members of the series being insoluble. In the same way that unsaturated hydrocarbons differ from paraffines in the presence of double or treble bonds between adjacent carbon atoms, so the unsaturated fatty acids differ from those given above. The un- saturated fatty acids, oleic, linoleic have respectively 1 and 2 double bonds. Linolenic has 3 double bonds. These unsaturated acids may take up oxygen and become saturated, and in this way they act as reducing substances. The oxy-acids contain more oxygen than the normal acids. Propionic acid is CH,CH,COOH whereas oxypropionic, usually called lactic acid, is CH,CHOH'COOH. Keto acids contain the ketone group, and also the COOH group. Fatty acids combine with bases to form salts, which in case of the higher members of the series are called soaps. The soaps formed by action of alkaline earths on the higher fatty acids aie insoluble in water whereas the lower fatty acids form soluble soaps with these bases. Alkali soaps hydrolize in water, forming a fine emulsion of fatty acid that makes the solution opalescent. Fatty acids combine with ammonia, but the compound may be of either of two forms. With ammonium hydrate, which is a true base, they form ammoniacal soaps, but with dry ammonia and a dehydrating agent they form acid amides containing one less molecule of water. In ammoniacal soaps N is pentivalent in the group COONH,, whereas in amides nitrogen is trivalent in the group CONH,. The esters of fatty acids with alcohols are called fats. The triatomic alcohol glycerol is the most common but the monatomic alcohol cholesterol and other alcohols are also found. Since glycerol is a triatomic alcohol, it can combine with one, two or three fatty acid molecules, forming mono-, di-, and triglycerides, of which the last is the most common. Fat globules found in cells are usually mixtures of triglycerides and fatty acids. In the analysis of fats, the acid number denotes the content of free fatty acids, the saponification number, or combining power with hot KOH, is an index of the average of molecular weight of each fatty acid divided by its valence, and the iodine number is an index of the content in unsaturated fatty acids. The percentage of volatile fatty acids is usually determined, but the separation of all of the fatty acids involves much labor. The oxidation of 1 1g. fat may yield as much as 9.5 calories of heat. Mono or diglycerides may combine with other substances by means of the remaining alcohol groups. Such compounds are included under the loose term, lipoids, but have been called by Leathes phospholipines, 192 APPENDIX galactolipines and lipines. Phospholipines are diglycerides in which the third alcohol group is combined with phosphoric acid. Since phosphoric acid is trivalent it can combine with two other substances, In lecithin it combines with only one other substance, the organic base, choline. The phospholipines are unstable and are partly decomposed and oxidized by extraction with hot solvents in the presence of air, and hence their com- Position has not been entirely settled in all cases. In galactolipines, galactose takes the place of glycerol. Lipines contain nitrogen but no carbohydrate or phosphoric acid. From fatty acids and ammonia may be prepared not only acid amides, but also amino acids (lactic acid with NH, and a dehydrating agent forms alanine). In the mono-amino acids obtained from mammalian cells the NH, group is at- tached to the carbon atom next to the COOH group. These acids are called alpha amino acids. In the diamino acids, an additional NH, group is attached to some other carbon atom of the chain. The amino acids have both acid and basic properties and are therefore called amphoteric. In the diamino acids the basic property predominates. Amino acids may be derived from dibasic acids, containing two COOH groups and in this case the acid property markedly predominates. The proteins are compounds of amino acids in which the NH, group of one molecule has reacted with the COOH group of another. The complete structure of none of the proteins is known, but many amino acids have been separated from the decomposition products, among which are: The monoamino acids, amino acetic or glycine, aminopropionic or alanine, amino isovalerianic or valine, and aminoisocaproic or leucine. The dibasic amino acids are aspartic and glutamic acids. The diamino acids are lysine, arginine, and diaminotrioxydodecoic acid. Cystine con- tains two atoms of sulphur. Other amino acids contain cyclic compounds, which will now be considered. Whereas in the compounds thus far considered the carbon atoms are arranged in an open chain, in the cyclic compounds they are in the form of a closed ring. The most important of these rings is the benzol ring containing 6 carbon atoms. Although this ring has only 6 H atoms there seem to be no double bonds between the carbon atoms, or if there are double bonds they do not behave as the double bonds of the unsaturated open chain compounds. In benzol, ‘C,H, each C atom is united to one hydrogen atom. The substitution of one or more hydrogen atoms by other atoms or groups gives rise to a host of compounds, When only one hydrogen is substituted it is immaterial which carbon atom it is attached to, but by its presence the other carbon atoms lying at different distances from the first one are designated as ortho, meta and para, and groups that may subsequently be attached to them are in the ortho, meta, or para position. Of the mono-substitution products of benzol we have aniline, C,H,NH,, benzol-sulphonic acid, C,H;SO;H, phenol, -C,H,OH, toluol, C,H,CH,, benzyl alcohol, C,H;CH.OH, benzaldehyde, C,HyCHO, and benzoic acid, C,H,COOH. Of the di-substitution products we have catechol (ortho-hydroxyphenol), resorcinol (meta-hydroxyphenol), hydroquinone (para-hydroxyphenol), salicylic acid (ortho-hydroxy benzoic acid), and tyrosin (para-hydroxy- phenylalanine). Tyrosin is an amino acid found in proteins. Some tri-substitution products are pyrogallol, homogentisic acid, picric acid and adrenaline. Adrenaline is secreted by cells of the adrenal medulla and is a specific stimulant (or in some cases inhibitor) of smooth muscle cells, although its action is supposed not to be on the whole cell surface but on a theoretical. receptor substance. The pyrrol ring contains 1 nitrogen and 4 carbon atoms and is con- tained in proline and oxyproline, amino acids found in proteins. Trypto- phane, another amino acid found in proteins, contains a combination of CHEMICAL SUMMARY 193 benzol and pyrrol rings and may be transformed into indol and skatol by the action of bacteria. . The imidazol ring contains three carbon and two nitrogen atoms H 4H C-——N ll % == Imidazol ring. H Cc H-C— N// and is contained in histidine, an amino acid found in proteins. hen protein is split into amino acids by any method, not all of the protein is thus accounted for. Now that the building stones of the proteins have been discussed, it is well to consider a few characteristics of these interesting substances. Proteins consist of the same amino acids but in different proportion. Glycine is absent from some proteins. Tyrosine and tryptophane are absent from gelatine. Proteins consisting almost entirely of amino acids are called simple proteins to distinguish them from those combined with other substances. In oxyhemoglobin, a simple protein is combined with hematin, an iron containing organic compound loosely combined with one molecule of O,. The nucleins that have been isolated from the nuclei of some cells are composed of a simple protein and nucleic acid. The nuclein may combine with more protein to form nucleo-protein. Nucleic acid contains phos- phoric acid and one or more purine bases, adenine or guanine, allied to uric acid. A ae OC C—NH = uric acid. | || >co HN—C—NH The glycoproteins, such as the mucins, contain a high percent of carbo- hydrate groups, which are also found in nucleic acid. The phosphoproteins, vitellin, casein, contain phosphoric acid that is not in the form of nucleic acid or lecithin. The lecitho-proteins are hypothetical, although both lecithin and protein exist in the crystalline yolk bodies of the frog’s egg. Hoppe Seyler con- sidered such substances to ibe true chemical compounds but others have regarded them as mixtures. One argument against their being mixtures is that the yolk bodies are clear and not turbid as colloidal gels or sols containing lecithin are. The molecular weight of simple proteins has been estimated as vary- ing from 14,000 to 30,000, whereas that of oxyhemoglobin iis about 16,000. Proteins have both acid and basic characters since they contain both COOH and NH, groups. Their acid character predominates when in alkaline solution and basic character predominates when in acid solution. Proteins are precipitated by heavy metals and the color bases of many dyes and by the same acids that precipitate alkaloids, namely tannic, metaphosphoric, picric, phosphomolybdic, phosphotungstic, tri-iodo-hydri- odic, chromic, bichromic, and the color acids of many dyes. ‘Certain bacteria have the power of splitting off ammonia from the amino acids of proteins, a process known as deamination. If the de- amination is accompanied by hydrolysis oxyacids are formed, whereas _ if reduction takes place fatty acids are formed. In the eggs of certain fish fats are formed from proteins. The glycerine necessary in the pro- cess arises from proteins and may possibly arise in part in the following manner. In the conversion of glucose into lactic acid glyceric aldehyde is formed, which by reduction becomes glycerol. ABBREVIATIONS USED IN LITERATURE LIST Anatomischer Anzeiger. Arch, f. Anat. Physiol. (Physiol Abt.) (Bu Bois Reymond, Engelmann). Archiv de Biologie (Van Beneden). Archiv fir Botanik. Annals of Botany. Ann, (Chem. u. Pharm. (Liebig) (= An. Pm.) iAmeritcan Chemical Journal. Ann. d. Chim. et ‘Phys. (= A. 'Phys.). Arch. Entwicklungsmech. (Roux). ‘Arch. f. Exp. Path. u. Pharmakologie. Archivio di Fisiologia. Arch. gesammt. Physiol. (Pfliger). \Archiy fir Hygiene. Archives Ital. d. Biol. ‘Archives of Internal Medicine. Arch, Internat. de Physiol. Arch. Internat. d. Pharmacodynam. Ann. d, l’Ins. d. Pasteur. American Journal of Anatomy. American Journal of Botany. Am, Jl. of Diseases of Children. Am. Jl. of the Medical Sciences. Am. Jl. of Physiology. American Journal of Science. (Archiv fiir Kinderheilkunde. Arb, a. d. kais. Gesundheitsamt. Annals Missouri Bot. Garden. American ‘Naturalist. Arch. Neerland. Ann. N. Y. Acad. of Science. iAnm. d. Physik (Poggendorf, Wied., Drud.) (= Jl. Pk. N, J. Pk. A. Pk. C.) Archiv fiir Pharm. Anatomical Record. Arch. d. Sci. Biol. Ann. d. (Sci. Natur. et Zool. Arch. Soc. Phys. ‘Nat. Geneva. ‘Ann, d. I'Univer. de Grenoble. Archiv fiir Zellforschung. Arch. d. Zoolog. Experim. et Gener. Bull. d. ’Acad. Roy. Belgique. Bull. Acad. Sc. Cracow. Math. Nat. Biological Bulletin. Bull. U. S- Bureau of Fisheries. Bull. U. S. Bureau of Standards. Biologisch. 'Centralblatt. Biochemical Bulletin. Beitrage Chem. Physiol. u. Pathol. (Hofmeister). BDBG BIDCG BGS BIOM ABBREVIATIONS 195 Berichte d. deutsch. bot. Gesell. Ber. d. deutsch. chem. Gesellschaft. Botanical Gazette. Bull. U. iS. Geological Survey. Bull. Hyg. Lab. U.S. Pub. Health & M. H. S. Bull. Inst. Oceanograph. Monaco. Biochemical Journal. Berliner klin, Wochenschrift. British Medical Journal. Bull. Museum Comp. Zool. Harvard. Bull. Soc. ‘Chim. Bull. Torrey Botanical Club. Berichte der Wiener Akad. Ber. Verh. Gesell. Wissens. Leipzig. Biochemische Zeitschrift. Botanisches Zeitung. ‘Carnegie Inst. Wash. Publication. ‘Compt. Rend. Acad. Sc. Paris. Compt. Rend. Soc. Biol. Paris. ‘Chemische Zeit. Deutsch. Archiv klin. Medicin. Deutsch. med. Wochenschrift. Ergebnisse allg. Path, u. path. Anat. Ergeb. d. Physiologie (Asher & Spiro). Flora. Gazetta ‘Chim. Ital. Internat. Rev. ges. (Hydrobiologie. Int. Zeitsch. physikochem. Biologie. Journal of Animal Behavior. Jl. of the Amer. Chemical Society. Jl. Amer. Medical Association. Jl. of Anatomy and Physiology. Journal of Biological an Jl. Coll. Engineering I. U. Jap. Tokyo. Jl. Comparative Neurol. & Psychol. Ji. Chim. et Phys. Ji. of the ‘Chemical ‘Society. Ji. Coll. Sc. Imp. Univ. Jap. Tokyo. Journal of Experimental Medicine. Journal of Experimental Zoology. Johns Hopkins Hosp. Bulletin. Journal of Infectious Diseases. Jl. of Laboratory & Clin. Medicine. Journal of the Linnean Society. Jl. Marine Biol. Assn. Unit. King. (n. s.) Journal of Medical Research. Journal of Physiology. Jl. de Pharmacie. Jl. de Physique, Theor. et Appl. Jl. Pathol. Bakteriol. Journal of ‘Physical ‘Chemistry. Ji. fiir prakt. Chemie. Jl. Pharmacol. Exp. Therapeutics. Jl. de Physiol. et de Pathol. General. Jl. Washington iAtcad. Sc. Jahrbucher wissenschaftl. Bot. Kolloidchemische Beihefte. Kolloid Zeitschrift. ABBREVIATIONS Landiwirtschaftliche Jahrbiicher. Memoirs Acad. Roy. Belgique. (Mionatshefte Chem. Minchener klinische Wochenschrift. Miinchener medizinische Wochenschrift. Medical Review of Reviews. Natur. Rundschau. Nordske. Vedenskabs. Schrift. Proc. Acad. ‘Nat'l, Science, Phila. Proc. Boston Soc. Natural History. Proc. Cambridge Philosophical Soc. Philosophical Magazine. Presse Medical. Proc. National Acad. Science. Pub. Nutrition Lab. Carnegie Ins. W. Physical ‘Review. Proc. Royal Society of London. Proc. Soc. Exper. Biol. & (Medicine. Popular iScience ‘Monthly. Philos. Transactions Roy. Soc. London. Plant World. Physikalische Zeitschrift. Quart. Jl. Experimental Physiology. Quarterly Journal of Medicine. Rec, Traveaux Chim. Pays Bas. Rendiconti R. Acad. dei Lincei. Science (n. s.). Skandinavisches Archiv Physiologie. Sitzungsb. kais. Pruss. Akad. Wiss. Sci. Proc. Roy. Dublin (Society (n. s.). Sitzungsber. Wiener Akad. Trans. Amer. Acad. Physicians. Trans. Amer. Electrochem. Soc. Trans. ‘Connecticut Academy. Trans. Chemical Society. Traveaux d. Il’Lab. d. Archachon. Transactions of the Faraday Soc. Univ. Penna. Medical Bulletin. Univ. Cal. Publications (Physiol.). Univ. Minn. Studies (Phys. Sc. & Math.). Verh. Ges. deutsich. Nat’f. u. Arzte. Vier’j’s. ‘Nat. Gesellsch. Zurich. Verhandl. Nat. Verein, Brinn. Verh. phys.-med. Gesellsch. Wurzburg. Ver. Kon. Acad. Wetens., Amsterdam. Wiener klinische ‘Wochenschrift. Zeitschrift anorganische Chemie. Zeit. allgemeine Physiologie. Zeitschrift fir Biologie. Zentralblatt fiir Bakteriologie. Botanik. Zeitschrift fiir Elektrochemie. Zeit. f. exper. Pathol. u. Therapie. Zeit. f. exper. Ther. Zeitschrift fiir Hygiene. Zeitschrift fiir _Immunitat. Zent. f. innere Med. (= Cent. klin. M. = C. I. M.) Zoolog. Jahrbucher (Zool. Physiol. Abt.). ZK ZKM ZP ZPa ZPk ZPC ZPkC ZRM ZWM ZWZ ABBREVIATIONS 197 Zeitschrift fir Kinderheilkunde. Zeitschrift fiir klinisch. Medizin. Zeit. fiir Nervenheilkunde (Deutsche). Zentralblatt fir ‘Physiologie. Zeitschrift fiir Pathologie. Zentralblat fiir Physik. Zeitschr. fiir physiolog. ‘Chemie. Zeits. fiir Physikalische Chemie. Zeitschrift fiir Rationell. Medizin. Zeit. fiir wissenschaft. Mikroskopie. Zeit. fiir wissenschaftlich. Zool. LITERATURE LIST Abegg, Auerbach & Luther 1911 ‘“Messungen Elektromot. Krafte gal. Kette.” Halle. Abderhalden 1898 Analysis of mammal blood. ZPC xxv 65. '1909 Milk-droplet membranes. ZPC lix 13 1910 “Handbuch d. Biochem ‘Afucilanetiedea” Berlin. 1911 “Biochem. Handlexikon.” Berlin. — & Gigon 1907 Yeast (splitting dipeptids) inhibited by l-amino acids. ZPC lit 251. —— & Guggenheim 1908 Shaking enzymes. Asymmetry. ZPC liv 331. —— & Hall 1908 “Text Book of Physiol. Chem.” N. — & Pringsheim 1909 Asymmetry and enzyme action. ZPC lix 249. Abel, Rowntree & Turner 1914 Diffusible constituents of blood. JPET Vv 275. Abl 1907 Anesthetic and electrode potential. Dissertation, Bonn. Acree & Johnson 1907 Enzymes displace equilib. pt. ACJ xxxviii 258. Adrian 1914 All-or-none law. JP xlvii 460. Agazotti 1906 PH of blood at low atm. pressure. RRAL (5) xv 481. Albutt 1910 Blood viscosity. QJM iv 342. Alcock & Lynch 191 K in nerve. JP xliii 107. Alexander & Cserna 1913 Narcosis and brain respiration. BZ liii 100. Allee 1914 Rheotaxis and KCN. JEZ xvi 397. —— & Tashiro 1914 (Rheotaxis and (CO, production. JAB iv 202. Allemand 1912 PH and rennin action. BZ xlv 346. Allen, F. 1916 Diabetes. JAMA Ixvi 1525. Allen, G. rorsa Bile and surface tension of urine. JBC xxii 503. 1915b ‘Reversibility of rheotaxis. BB xxix JI1I. Allen, E. & Nelson 1910 Diatom culture. JMBA viii 421. Allen, H. 1913 “Photoelectricity: the Lib. of Electrons by Light.” London. Armstrong, E. 1903 Enzymatic splitting and synthesis of sugars. JCS Ixxxiii 1305. 1904 enon of invertase inhibited by fructose. PRS (B) 1xxiii 500, 516, 520. Armstrong, H. 1908 Properties of water. PRS (A) 1xxxi 80. Arrhenius 1887 Ionization. ZPkC i 631. 1889 Osmotic pressure and vapor pressure. ZPkC iii 115. 1892 Usually ions decrease and non-electrolytes increase viscosity of water. ZPkC x 51. rgo1 “Lehrbuch der Elektrochemie.” Asher & Karaulow 1910 Permeability of salivary cells to sugar. BZ xxv 36. —— & Spiro 1902-1915 Ergebnisse der Physiologie. Wiesbaden. —— & Waldstein 1906 Increased blood pressure not diuretic. BZ ii 1. Atkins 1910a A Marine vertebrates. BJ v 213. 1910b Beans not semipermeable. SPRDS xii 35. tg910c A Plant juices. SPRDS xii 463. Aubert 1912 Thermo-osmose. AICP xxvi 145, 351. Auer & Meltzer 1916 MgSO, anesthesia. JPET Xxiii 641. Auerbach 1912 Ex of N/io Cal. Elec, = 337, 0 PogRe ZEC xviii 13. 1912 PH of N/1o NaHCO, = 8&3 at 25°. AKG xxxviii 242. 1913 PH for Trypsin on Peptone = 8.3 = NaHCO,. BZ xlviii 4s. LITERATURE LIST 199 Austrian 1911 Case of visc. blood = 13.6. JHHB xxii 9, Bach & Chodat 1904 Oxygenase and peroxidase. BDCG xxxvi 606. Bachman 1912 A of amphibian eggs. AGP cxlviii 141. —— & Runnstrom 1909 A of frog’s eggs = .045. BZ ccii 290. 1912 Unfertilized frog’s egg swells more than fertilized. AGP cxliv 287. —— & Sundberg 1912 A of tadpoles. AGP cxlvi 212, 287. Bachmann ‘1912 Ultramicroscopy of soaps. KZ xi 145. Bachmetjew 1900 Undercooling of insects. ZWZ Ixvii 520. Bayer 1902 O,-Need of nerve. ZAP ii 160. ; Bainbridge 1902 Bile salts increase secretion and lymph production of liver. JP xxviii 204. —, Collins & Menzies 1913 Frogs’ glomeruli secrete isotonic urine. PRS (B) Ixxxvi 353. Baltzer 1911 Mitosis. AE xxxii 500. Bancels, des 1909 Effect of ions on Polarization. CRA cxlix 316. Bancroft 1906 Reversal of galvanotropism. UCPP iii 21, JP xxiv 444. Banta 1912 Development and respiration. PSEB ix 104. Barcroft 1914 “The Respiratory Function of the Blood.” Cambridge University Press. — & Brodie 1905 Osmotic work and kidney metabolism. JP xxxiii 52. — & Camis 1909 Dissociation of oxyhemoglobin. JP xxxix 118. — & Hill 1910 Effect of temperature on dissociation of oxyhemoglobin, JP xxxix 81, —— & Straub 1910 Kidney metabolism and osmotic work. JP xli 145. Barker, Hirschfelder & Bond 1910 Electrocardiogram. JAMA Iv 1350. Banta & Gortner 1915 Displacement of organ forming substance. JEZ XVili 433. Barger 1904 Microtensimeter. TCS Ixxxv 286. & Starling 1915 Adsorption of iodine. TCS cvii 411. Barlow 1896 Eausion of sugar causes greater hydremia than urea. JP xix 418. Bartell 1911 Permeability. JPC xv 659. 1912 Diameter of pores and osmose. JPC xvi 318, 1914 Negative osmose. JACS xxxvi 646. —— & Hocker 1916 Negative osmose and diffusion emf. JACS xxxviii 1029, 1036. Bartelzko 1909 Freezing and plasmolysis. JWB xlvii 57. Barns 1889 Suspensoids precipitated by ions not by electrolytes. AJS Xxxvii 122, ; Bataillon 1910 Parthenogenesis with foreign sperm. AZEG (5) vi ror. 1g11 Parthenogenesis by pricking and electricity. CRB Ixx 562. 1912 Parthenogenesis. ASNZ (9) xvi 249. Batelli & Stern 1907 Cell respiration, JP ix 1, 34, 228, 410, 737. 1909 Oxidation. BZ xxi 487, xxxiv 263. 1910 Oxidation. BZ xxiii 145. 1913 Anesthetics precipitate protein. BZ lii 226, 253. Bates 1912 Faraday = 96500 coulombs. Thesis, U. of III. Bauer 1913 Model of electric organ. ZEC xix 590. Bayliss 1906 Adsorption and electric charge. BJ i 173. 1908 Frog’s skin, or bag of Congo red solution acts as electric recti- fyer. BZ xi 226. : 1909 Osmotic pressure of Congo red. PRS (B) Ixxxi 269. 1910 Membrane hydrolysis. KZ vi 23. 1911 Permeability and polarization. PRS (B) Ixxxiv 245. 1913 Asymmetry and enzyne action. JP xlvi 236. ig15a “Principles of General Physiology.” Longmans. 1915b Enzymes may act in non-solvent media. JP 1 85, S xlii S00. 1916 Viscosity and blood pressure. JP 1 (p. xxiii). 200 LITERATURE LIST Beard & Cramer 1915 Surface tension and ferments. PRS (B) Ixxvili 575. Beccari 1915 K within physiol. limit stimulating to muscle. AIB Ixiii 293. Bechhold 1904a “Irregular Series” of ionic and colloidal precipitation, Bacteria are anodic. ZPkC xlviii 385. 1904b Electrolytic solution tension and precipitating power. ZPkC xlviii 406. 1907 Permeability of membranes. ZPkC 1x 257. 1908 Ultrafilter. ZPkC Ixiv 328. 1912 “Die Kolloide in Biologie und Medizin.” Dresden. — & Ziegler 1906 Diffusion in gels. ZPkC lvi 105. 1910 Solubility of uric acid in serum. BZ xxiv 146. Beddard 1902 Dyes not excreted by glomeruli of frog’s kidney, but by tubules. JP xxviii 20. Begun, Hermann & Miinzer 1915 Alv. CO, (Plesch) 6%. Drank 20 g HCl and Alv. CO, fell 1%. BZ Ixxi 255. Bein 1899 Effect of membrane on transport numbers. ZPkC xxviii 439. Benecke 1898 Ca-free water causes cells to fall apart. JWB xxxii 474. Benedict & Cathcart 1913 Muscular work. PNL (No. 187). Benedikt 1906 PH of diabetic blood. AGP cxv 106. ‘Beniasch 1912 Acid agglutination. ZI xii 268. Bennett & Cole 1912 Regeneration of storage cells. TAES. Benson 1902 Adsorption on foam. JPC vii 532. Benson & Wells 1910 Antolysis. JBC viii 61. Benrath & Sachs 1905 Formation of HCl by stomach. AGP cix 460. Bequerel 1901 Seeds survive complete dessication, CRA cxxxix 1721. Berczeller 1913 Change of surface tension of colloids. BZ liii 232. 1914 Surface tension of alkaline solutions of lecithin increased by ether or chloroform. BZ Ixvi 226. —— & Csaki 1913 Surface tension of alkaloids. BZ liii 238, Berg 1912 Muscle contraction. BCB ii rot. Bergeim 1914 Origin of gastric HCl. PSEB xii 21. Berkeley & Hartley 1904 Osmotic pressure of sugar. PRS Ixxiii 436. 1906 Osmotic pressure of conc. sol. PT (A) ccvi 481. Bernoulli 1913 Sulphates and nitrates temporarily reduce effect of bro- mide intoxication. AEP Ixxiii 353. Bernstein, E. & Simons 1911 Meiostagmine reaction. AJMS cxlii 852. Bernstein, J. 1866 Polarizability of nerve lessened by stimulants. AP 506. 1900 Imitation of ameba. AGP Ixxx 628. 1g01 Surface tension theory of muscle contraction. AGP Ixxxv 271. 1902 Theory of bioelectric currents. AGP xcii 521. 1908 Temperature coefficient of muscle contraction and surface ten- sion is negative and of swelling positive. AGP cxxii 129, cxxiv 462. 1910 Thermo. currents of muscle. AGP cxxxi 580. 1912 “Elektrobiologie.” Braunschweig. Vieweg. 1914 Muscle contraction. AGP clvi 299. 1915 Swelling causes no contraction unless previously stretched or twisted. AGP clxii 1. —— & Von Tschermak 1906 Electric organ. AGP cxii 439. Bert, Paul 1878 La pression barometique. Paris, Masson. Berthelot & Gaudechon 1910 Photosynthesis of carbohydrates. CRA cl 1690. — & Jungfleisch 1872 Partition coefficient independent of concentra- tion. ACP (4) 306, 408. Bethe 1908 Van’t Hoff solution. Toxicity of sugar. AGP cxxiv 541. 1909 Movements of medusa and perm. to H’ and OH’. AGP exxvii 219. 1911 Electroendosmose. MMW Iviii 168. 1914 Blood corpuscles of ascidians more permeable to acid than to basic dyes. BIOM (No. 284). 1916 Stimulation due to H’. AGP clxiii 147. LITERATURE LIST 201 — & Toropoff 1914 Change of reaction by electroendosmose. ZPkC Ixxxviii 686. Beutner 1912a Colloidal and osmotic swelling. BZ ix 280. 1912b Concentration cells. BZ xlvii 73. 1913a Concentration cells. ZEC xix 319. 1913b Concentration cells. JPC xvii 344. 1913c Colloidal and osmotic swelling. BZ xlviii 217. 1913d Concentration cells. JACS xxxv 344. 1913e Concentration cells. AJP xxxi 343. . 1913f Concentration cells. TAES xxiii 4o1. Bialaszwicz 1908 Swelling of egg. BASC 783. _ 1912 A of chicks and tadpoles. AE xxxiv 489. Bigelow 1808 Negative catalysers. ZPC li 585. 1907 Filtration same through porcelain and colloidal membranes. JACS xxic 1675. —— & Bartell 1909 Pores in membranes. JACS xxxi 1194. Billard & Bruyant 1905 Surface tension and locomotion. CRB lix 102. — & Dieulafe 1902 Surface tension of bile = .66. CRB liv 325. Billiter 1913 Polyvalent ions and cataphoresis. APk (4) xi 902. 1904 Clearing of sols with sols of same sign. BWA cxili I159. 1905 Surface tension and electrode potential. ZPkC li 1209. Biltz, H. 1899 Phototropism of dyes. ZPkC xxx 527. Biltz, W. 1904 Adsorption compounds of immune bodies. ZPkC xlviii 615. 1904 Colloidal hydroxides positive. BDCG xxxvii 1095. I913 Osmotic pressure of dextrin. ZPkC Ixxxiii 683. — & Steiner 1910 Adsorption hydrolysis. KZ vii 113. Bingham & Durham 1911 Viscosity of suspensoid sols greater than water. ACJ xlvi 278. Bjerrum 1908 KCI lowers diffusion potential. ZPkC liii 428. Bock & Hoffmann 1871 NaCl infusion causes glycosuria. AP 550. Bodenstein 1913 Photochemistry. ZPkC Ixxxv 329. —— & Dietz 1906 Enzyme changes equilibrium point. ZEC xii 605. Bodlander & Fitting 1902 Solubility of ammoniacal silver salts. ZPkC XXXIX 507. Béhm 1909 Increase in blood pressure does not decrease volume. BZ Xvi 313. Bohn, G. 1904 Rhythm in littorina. CRA cxxxix 646. 1907 Rhythm in diatoms. CRB Ixii 121. Bohr 1894 Secretion of gas into air bladder. JP xv 404. 1904 Dissociation of oxyhemoglobin. ZP xvii 683. —— & Hasselbach 1903 Calorimetry of embryos. SAP xxii 221. Boldyreff 1015 Regurgitation from duodenum to lower gastric acidity. vill I. Bonnevie 1910 Mitosis. AZ v 1. Boothby 1913 Anaesthesia. JPET v 370. —— & Peabody 1914 Alveolar air. AIM 497. Bordet 1899 Agglutinins do not agglutinate bacteria if ions are absent. AIP xiii 225. Boruttau 1916 Ions and action current. ZP xxxi 1. Bose 1913a Velocity of excitation impulse in plants. PT (B) cciv 63. 1913b “Researches on the Irritability of Plants.” Longmans, Botazzi 1897 A of marine animals. AIB xxviii 61. 1905 A of marine animals. AF iii 416, 1909 Change of surface tensions of colloids. AF vii 593. 1911 Surface tension of lymph = 89. Neuberg’s “Die Harn.” 1913 Hemoglobin negative. AF xi 397. —— & Craifaleanu 1916 PH of nerve juice = 6.04, of grey matter juice = 612. RRAL xxv 73. 202 LITERATURE LIST —— & Ducceschi 1896 A and buffer value of blood. AIB xxvi 161. — & Enriquez 1901 Octopus gland in sea water absorbs water on stimu- i lation. AIB xxxv 169. Bournat 1909 Effect of ions on electroendosmose. CRA cxlix 1366. Bousfield 1912 Ionic size. PRS (a) 1xxxviii 147. — & Lowry ig10 Association of H.O. TFS vi 15. Boveri 1908 Viscosity of blood. PrM Ixiii 546. Bovie 1913 Coagulation by ultra violet light. S xxxvii 24. 1915 Direct reading potentiometer. JMR xxxiii 295. Bradley 1910 Lipase. JBC viii 251. 1913 Enzyme synthesis. JBC xiii 407-431. — & Taylor 1916 Gelatine abolishes latent period in autolysis. JBC xxv 363. Bredig 1894 Speed of organic ions. ZPkC xiii 191. 1898 Metal sols. ZEC iv 514, 547. 1899 Acids and alkalis increase dissociation of ampholytes. ZEC vi 33. 1go1 “Anorganische Fermente.” Leipsic. 1907 Specific catalytic action of potassium bichromate. Rhythmic catalysis. BZ vi 283. —.& Fajans 1908 Asymmetric catalysis. BDCG xli 752. — & Fiske 1912 Asymmetry and catalysis. BZ xlvi 7. & Weinmayr 1903 Rhythmic catalysis. ZPkC xlii 602. Brodie & eet 1910 Increased respiration of gut during resorption. JP xl 135. Brown, A. 1909 Permeability of barley grain same as plasma membrane, PRS (B) Ixxxi 82. Brown, H. 1914 Storage of oxygen by yeast. AnB xxviii 197. Brown, O. 1903 Fundulus egg protoplasm anodic. AJP ix 111. 1905 Fundulus egg good insulator. AJP xiv 354. Brown, W. 1915 Dilute alcohol increases permeability of collodion sacs. BJ ix 591. Briinings 1903 Bioelectric currents. AGP c 367. 1907 Bioelectric currents. AGP cxvii 400. Birker 1910 Anodic oxidation of anaesthetic proportional to anaesthetic power. MMW lvii 1443. Buchner & Rapp 1899 Fermentation and oxidation. ZB xxxvii 82. Bugarsky 1897 Calculation of SO,” from electrode potential. ZAC xiv 145. —— & Liebermann 1898 Buffer value of proteins. AGP Ixxii 51. —— & Tangl 1898 Conductivity of serum = .125 n NaCl. AGP Ixxii 545. Buglia 1907 A of blood increased by passage through active muscle. BZ vi 158. 1908 Maximum surface tension of emulsoids at isoelectric point. BZ xi 311. Bunsen & Roscoe 1862 Photochemical law. APk cxvii 538. Bunzel 1914 Oxidase apparatus. JBC. 1916 Oxidases. JBC xxiv o1, 103. Burch 1892 Calibration of rapid excursion of capillary electrometer. PT (A) clxxxiii 81. Burdon-Sanderson 1882 Action current of plants. PT 1. 1888 Action current of plants. PT clxxix (B) 417. Burge 1914 Oxidation of pepsin. AJP xxxiv 140. Burian 1910a Bony fish secrete hypotonic urine. AGP cxxxvi 741. 1gtob Ultrafiltration. ZP xxiii 767. — & Drucker 1910 Small thermometer for A. ZP xxiii 772. Burri & Nussbaum 1909 Surface tension of milk = .685. BZ xxii 90. Burton 1906 Speed of colloids in potential gradient same as ions. PM (6) xi 425. LITERATURE LIST 203 1906 Electrolytes decrease speed of colloid particles. Effect of poly- valent ions. PM (6) xii 472. Burton-Opitz 1911 Viscosity of blood. JAMA lvii 353. 1914 On laking blood becomes more then less viscous. AJP xxxv 51. Busquet & Pachon 1908 Ca on heart. CRB Ixv 590. Buxton & Rahe 1909 Opposite sols precipitate only in equivalent propor- tions. JMR xx 113. —— & Shaffer 1906 Electrolytic solution tension and precipitating power. ZPkC lvii 47. ——, Shaffer & Teague 1906 Reversal of charge of sols with sols of op- posite sign. ZPkC lvii 47, 64. Byers & Walter 1914 Electrolytic endosmose. JACS xxxvi 2284. Callaud (& Pelletier) 1821 Chemiluminescence. JPm vii 579. . Calugareanu 1910 Anaesthetics increase size of colloid particles by dis- solving in them. BZ xxix 96. — & Henri 1902 Salts diffuse from erythrocytes into isotonic sugar solution. CRB liv 210, 356. Campbell, Douglas, Haldane & Hobson 1913 CO., H, and respiratory center. JP xlvi 301. Cannon 1897 Movements of stomach, AJP i 359. — & Cattell 1916 Action current of glands. AJP xl 143. Carlson 1906 Anesthetics increase rhythm. AJP xvii 182. 1911 Stretching nerve and conduction rate. AJP xxviii 323. ——, Greer & Luckhardt 1908 A of lymph and blood same yet lymph con- tains more colloids. AJP xxii 91. , Orr & Brinkman 1914 Powlow-gastric juice. AJP xxxiii 86. Carrell & Guthrie 1905 Transplanted kidney secretes hypotonic urine. S xxii 563. Cary 1916 Regeneration. JEZ xxi 1. Cathcart 1904 Serum antitryptic. JP xxxi 407. Cernovodeanu & Henri-1906 Bacteria are anodic. CRB 1xi 200, Cesana 1913 Ultramicroscopy of catalysis. AF xi 130. Chambers 1915 Microdissection. S xli 290. Chapin 1902 CO, stimulates plant growth similar to ether. F xci 348. Chiari 1909 Ether increases antolysis. AEP Ix 256. tg11 Action of acids and alkalis on swelling of glutin. BZ xxxiii 167. —é& es I91I Vagus action on heart abolished with oxalates. AEP xvi IIO. —— & Januschke 1911 Formation of exudates inhibited by Ca. AEP Ix 120, WKW xxiii 427. Chick & Martin 1912 Ppt. of heated proteins. JP xlv 261. Child 1911 Amitosis. BB xxi 280. 1913 Cell respiration. JEZ xiv 153. Choquard 1913 Narcosis of fat and lean tissues. ZB Ix 1. Christianson, Douglas & Haldane 1913 CO. from blood. JP xlvii (p ii). Clark ed ie prolonged action of Hg salts ionization unimportant. JPC ii 263. Clark, A. 1913 Action of ions and lipoids on frog’s heart. JP xlvii 66. Clark, W. 1915a PH of cultures. JBC xxii 87. 1915b H, electrode. JBC xxili 475. ro1sc PH of modified milk. JMR xxxi 431. ig1gd PH of cultures. JID xvii 109. — & Lubs 1915 PH of cultures. JID xvii 160. 1916 Buffer mixtures. JBC xxv 470. Clarke 1911 Analysis of sea water. BGS (no. 491) 113. 1916 Ash of marine invertebrates. S xliii 723. Clausen 1890 Respiration of plants doubled by 10° rise in temperature. LJ xix 893. 204, LITERATURE LIST Clowes 1903 A and sp. gr. of urine. AJP ix 319. 1916 Soap gelation and permeability. PSEB xiii 114, JPC xx 407. Coblentz 1912 Temperature and spectrum of firefly. CIWP (No. 164). Coehn 1898 Suspensions of lower dielectric constant than water are ano- dic. WAP Ixiv 217. 1909 Tyndall phenomenon of sugar solutions, ZEC xv 652. —— & Barrat 1905 Galvanotropism. ZAP v I. Cohnheim 1898 Very hypertonic solution in, gut draws water and salts out of blood. ZB xxxvi 129. 1901 Negative osmose through holothurian gut. ZPC xxxiii 9. 1902 Negative osmose through gut of octopus. ZPC xxxv 416. 1913 Chopped kidney binds NaCl and sugar when it exceeds a cer- tain concentration. ZPC Ixxxiv 451. — & Von Uexknell 1912 Catch-action of smooth muscle. ZPC Ixxvi 314. Colton 1910 Surface tension. PANS 42. Compton 1915 Optimum PH for maltase 7.2 at 47°, 3 at 35°. PRS (B) Ixxxviii 408. : Conklin 1908 Movements in dividing eggs. Biol. Lect. Woods Hole. 69. 1912 Cytoplasm nucleus ratio. JEZ xii 1. Constantino 1914 Erythrocytes permeable to amino acids. AIB 1x 442. Cooke 1898 Increased osmotic pressure of tetanized muscle. JP xx 137. Corral 1915 Dilution to %4 does not change PH of blood. BZ Ixxii 1. Correns 1891 Turgor. JWB xxii 161. Craw 1905 Toxin-antitoxin reaction. PRS (B) Ixxvi 170. Cramer 1915 Surface tension and metabolism. PRS (B) Ixxxviii 584. Cremer 1906 Concentration cells with membranes permeable only to H ions. ZB xlvii 562. : Cumming & Gilchrist 1913 Diffusion potential in wide tube. TFS ix 174. Curtis, H. A. —— Non-inductive resistances. BBS (no. 3, 8). ~ Cushny 1901 Diuresis and permeability. .JP xxvii 429. 1902 Blood pressure and diuresis. JP xxviii 443. Cybulski 1903 Membranes and concentration cells. BASC 622. — & Dunin-Borokowski 1909 Effect of gelatine membrane on concen- tration cell. BASC 660. Czapek 1902 Homogentisinic acid and geotropism. BDBG xx 464. 1910 Plants killed by solutions of surface tension — .68. BDBG XXVili 159, 490. Dahlgren 1914 Origin of electric organ. CIWP (No. 183) 159. Dakin, H. 1905 Asymmetry and enzyme action. JP xxxii 199. 1912 “Oxidations and Reductions in the Animal Body.” Longmans. Dakin, W. 1908 Change of A of fishes, BJ iii 258. Dale 1911 Galvanotropism of infusoria. JP xxvi 291. Danysz tgo2 If antitoxin is added slowly more free toxin is left than if added suddenly. AIP xvi 331. D’Arsonval 1889 Surface tension and bioelectric phenomena. AP 460. 1901 Resistance of bacteria to cold. CRA cxxxiii 84. Darwin, Francis 1903 Artificial rhythm in plants. Davenport 1897 Swelling of frog’s embryos. PBS xxviii 73. Davidsohn 1912 Proteolysis in infants’ stomachs. ZK iv 208. 1913a Methods for gastric analysis. Buffer value of stomach. ZK ix 470, 1913b PH and lipase. BZ xlviii 240. Davies 1907 Adsorption and solid solution. JCS ix 1666. Davis 1915 Surface tension of H.SO, solutions. Thesis, Columbia U. Dawes 1905 Adsorption of colloids irreversible. BCPP vi 426. Deetjen 1909 Alkalinity causes dissolution of blood platelets. ZPC Ixiii 1. Dekhuisen 1904 A of fresh water animals. ANd x 121. Delage 1902 CO, causes parthenogenesis of starfish, AZEG (3) x 213 1907 Parthenogenesis, AZEG xxxvi (N & R no. 2). LITERATURE LIST 205 DeMeyer 1911 Swelling of sperm in egg extracts. AB xxvi 65. Demoor 1894 Asphyxia of cells. AB xiii 163. 1907 Swelling and A of organs. AIP iv 340. D’Errico 1907 A of fowl = .616°. AF ix 453. Denham 1908 Salt hydrolysis. TCS xciii 41. Denis 1913 Fish blood and urine. JBC xvi 380. DeVries 1884 A of plant juices. Isotonic solutions. JWB xiv 427. 1885 Permeability of vacuole membrane. JWB xvi 465. Dietz 1907 Catalysis in diphasic system. ZPC lii 279. Dole 1914 Analysis of sea water. CIWP (no. 182) 71. Donaldson 1916 “The White Rat.” Donders 1872 Dissociation of oxyhemoglobin. AGP v 20. Donnan 1911 Osmotic pressure of Congo red. ZEC xvii 572. —& pearan 905 Surface tension of urine, normal = .9, icterus = .75. 1636. —— & Harris 1911 Osmotic pressure of Congo red. TCS xcix 1554. —— & Potts 1910 Dispersion of soaps. Haptogen membranes and emul- sions. KZ vii 208. Denclaes Hekisns & Haldane 1912 Dissociation of oxyhemoglobin. JP xliv 275. —, Haldane, Henderson & Schneider 1913 Adaptation to high altitudes. PT (B) cciii 185. Dreser 1893 Toxicity and ionization. AEP xxxii 456. Drew 1914 Denitrifying bacteria in sea water. CIWP (no. 182) 9. Dreyer & Roy 1911 Blood volume. PT (B) ccii 191. & Walker 1912 Resistance of dry bacteria to heat. JPB xvii 142, Drury 1914 Microchemistry of oxidation. PRZ (B) Ixxxviii 166. Drucker 1913 Calculation of Ba*’ from electrode potential. ZEC xix 804. Dubois 1913 “Mechanisme intime de la production de la lumiere chey les organismes vivants” (Soc. Linneenn de Lyon) (A. Rey). DuBois-Reymond Resistance of muscle less in tetanus (II, i, 82). “Unter- suchungen ueber tierische Elektricitaet.” 1916 Muscle contraction. BKW liii 393. Duclaux 1870 Surface tension curve. ACP (4) xxi 383, 427. 1905 Osmotic pressure of suspensoids, CRA cxl 1544. 1909 Osmotic pressure of colloids. JCP vii 405. Dupré 1866 Surface tension-adsorption curve. ACP (4) vii 409, ix 379. Durig 1901 Absorption of water by frogs. AGP Ixxxv 401. Dutrochet 1835 Negative osmose. ACP (2) 1x 337. Ebbecke 1894 Sudden increase of pressure to 300 atmospheres causes con- traction of narcotized muscle. AGP clvii 79. Edridge-Green 1915 Color vision. JP xlix 265. Ehrenberg 1913 Lyotrope series in gelatine swelling depends upon con- centration of salts. BZ liii 356. Ehrlich 1885 “Das Sauerstoff-Beditirfniss des Organismus.” Berlin, Hirsch- wald. Einstein 1908 Brownian movement. ZEC xiv 235. Einthoven 1901 String galvanometer, ANd (2) vi 625. Eisenberg & Okoloska 1913 NaCl increases toxicity of phenol. ZB Ixix 312. —— & Volka 1902 Adsorption of agglutinin by bacteria. ZH xl 154. Eisler 1909 Pure salt solution cause involution forms of bacteria. ZB (1) li 546. —& Vea Portheim 1909 Al’ retards entrance of methyl violet into cells. BZ xxi 50. Ellis, J. 1916 Concentration (activity) of H’ in HCl. JACS xxxviii 737. Ellis, R. 1912 Effect of ions on oil sols. ZPkC Ixxx 597 and Ixxviii 32I. Embden & Kraus 1912 Lactic acid produced by liver. BZ xlv 1. —— & Kondo 1012 Lactic acid production in muscle-press-juice inhibited by H’ (addition of alkali increases yield). BZ xlv 63. 206 LITERATURE LIST Emmerling 1901 Specificity of enzymes. BDCG xxxiv 600, 2206, 3810. Emslander 1914 PH of liver. KZ xiv 44, xxiv 3810. Endler 1912 Permeability of protoplasm. BZ xlii 440, xlv 402. Engelmann 1882 Phototropism. AGP xxix 387. 1893 Violin E-string swells and shortens in dilute acids or alkalis or on heating. “Ueber den Ursprung der Muslelkraft.” Leipsic. Engler & Wild 1897 Peroxides and oxidation. BDCG xxx 1669. Erlenmeyer 1913 Asymmetry and synthesis. BZ lxiv 382. Euler 1907 Displacement of equilibrium point by enzymes. ZPC lii 146. —— & Pope 1912 “General Chemistry of Enzymes.” N.Y. Wiley. Erb 1906 Adrenalin causes reduction of blood volume. DAKM Ixxxviii 36. Erlanger & Garrey 1914 Faradic stimuli. AJP xxv 337. Ernst 1901 Temperature optimum for catalysis. ZPkC xxxvii 448. Evans 1906 Adsorption of NaCl, KCl, etc. JPC x 200. Evans & Schuleman 1914 Permeability to colloidal dyes. S xxxix 443. Ewald 1912 Reversal of phototropism by electrolytes. JEZ xiii 591. Ewart 1903 “Protoplasmic Streaming in Plants.” Oxford, Clarendon Press. Fahr 1909 Permeability of muscle. ZB lii (NF) xxxiv 72. Fajans 1910 Asymmetry and catalysis. ZPC Ixxiii 25, Ixxv 232. Falk & Nelson 1912 Hydrolytic action of amino acids. JACS xxxiv 828. Fallois 1901 Increased oxygen pressure. AB xvii 713. Fano & Botazzi 1896 A of portal blood. AIB xxvi 45. —— & Mayer 1907 Surface tension of serum = .82, AF iv 165. Faraday 1834 Catalysis by metals. PT. 1857 Protection colloids. PT 154. Farkas 1903 PH of serum. AGP xcviii 551. —— & Scipiades 1903 Blood during pregnancy. AGP 577, 581. Fenton 1894 Oxidation of tartaric acid by iron. TCS Ixv 809. Fernbach 1890 Alcohol increased permeability of fungi to enzymes. AIPr iv 672. 1906 PH and diastase. CRA cxlii 285. Field & Teague 1907 Immune bodies cathodic. JEM ix 86. Fienga 1910 Effect of salts on smooth muscle. ZB liv 230. Findlay 1908 Adsorption of CO, by sols. KZ iii 169. 1913 “Osmotic Pressure.” Longmans. Fischel 1906 Granules and cell division. AE xxii. Fischer, A. 1895 Permeability of bacteria to salts. 1899 “Fixierung Farbung and Bau des Protoplasmas.” Jena. Fischer, E. 1898 Asymmetry and enzyme action. ZPC xxvi 60. —— & Abderhalden 1907 Asymmetry and enzyme action. ZPC li 264. Fischer, H. & Jensen 1909 Freezing out of colloids. BZ xx 143. Fischer, M. 1908 Salts reduce the swelling action of acids and bases on proteins. AGP cxxv 99. 1914 “Oedema and Nephritis.” 2nd Ed. N, Y. —— & Moore 1907 Action of acids and alkalis on swelling of fibrin. AJP XX 330. — & Sykes | 1914 Alcohol and acetone retard swelling of gels. KZ xiv. Fitting 1906 “Reizleitungsvorgange bei der Pflanzen.” EP v 155. I9It A of desert plants. ZB iii 200. Fitzgerald 1910 Location of HCI in gastric tubules. PRS (B) Ixxxiii 56. Fleisher & Loeb, L. 1910 Absorption from serous cavities. JEM xii 288, 487. Fleischhamer 1913 Salts produce current of injury of heart. ZB Ixi 326. Fletcher 1913 Lactic acid in muscle. JP xlvii 36r. —— & Brown 1914 CO, production and beat rigor of muscle. JP xlviii 177. — & Hopkins 1907 Lactic acid is not burned by O, if muscle is chopped up. JP xxxv 247. Flexner & Noguchi 1906 Diffusion of colloids. JEM viii 547. LITERATURE LIST 207 Fluri 1909 Polyvalent ions increase permeability of Spirogyra. F xcix 81. Flusin oo Negative osmose and swelling of membrane. ACP (8) xiii 480. ; 1908b Osmose and hydration of membrane. JPq (4) vii 291. Forschhammer 1865 Analysis of sea water. PT clv 203. Forster 1873 Dogs die from lack of salt. ZB ix 297, 369. a Fowler, Bergeim & Hawk 1915 Indicators for stomach. PSEB xiii 58. Fraenckel 1904 Curve of conductivity of blood, and erythrocyte volume. ZKM lii (hs). 1905 PH of gastric juice. ZEP i 1, 431. 1907 Catalyser used up in catalysis. ZPC 1x 202. Frankforter & Kritchensky 1914 Catalysis. UMS (No. 2). Franz, F. 1903 Hirudin. AEP xliv 342. Franz, V. 1909 A of marine animals. IRGH ii 557. Fredericq 1904 A of shark changes with sea water. AB xx 7009. Frenkel & Cluzet 1901 Surface tension of urine. JPP iii 99. Freund 1913 Na favors and Ca inhibits fever, AEP Ixxiv 311. Freundlich 1903 Rate of addition of electrolyte to sol. ZPkC xliv 143. 1907 Zdeompbions formula, reduction of heavy metals by. ZPkC Ivii 385. 1909 “Kapillarchemie.” Leipsic, Akad Verlag. 1g10 Adsorption, solid solution, potential and precipitating power. ZPKC Ixxiii 385, 307. 1916 Negative osmose. Electrostenolysis. KZ xviii 11. — & Bjercke 1916 Oxidation rate of oxalic acid by charcoal determined by diffusion. ZPkC xci 31. — & Loser 1907 Adsorption hydrolysis. ZPkC lix 284. —& er 1909 E M F produced by gravity or suspensions. ZEC xv 161. —& oe 1g09 Ionic exchange. Reversibility of adsorption. ZPkC XV11 536. — & Schucht 1912 Precipitation of As.S;-sol by ions. ZPkC Ixxx 564. 1913 Adsorption and suspensoid precipitation. ZPkC Ixxxv 641. —— & Von Elissafoff 1912 Adsorption potential of colloids. ZPkC Ixxix 407. Frey 1910 Reduction of Cl in blood by feeding NaBr. ZEP viii. 1912 Narcosis with ethyl chloride. BZ xl 29. Friedemann & Friedenthal 1906 Albumins precipitated by nucleic acid. ZEP iii 73. Friedenthal 1900 Proteins and carbohydrates not absorbed from gut by lacteals. AP 252. 1903a Buffer value of serum. AP (physiol. Gesell. 1903). 1903b Indicators. ZEC x 113. 1903c Tensimeter. ZP xvii 437. 1904 PH of serum and indicators. ZAP iv 44. 1911 Significance of salts in milk. MMW 238s. Frolich & Meyer 1912 Action-current of contracted muscle. ZP xxvi 269. Frozee 1909 Electrical stimulation to growth. JEZ vii. Fithner 1912 Narcosis and evolution. ZB Ilvii 465. —- & Neubaur 1907 Hemolysis, H’ and OH’, and partition coefficient. AEP lvi 333. Gager 1908 Radium and growth. AN xlii 761. Galeotti 1901 Na’ antitoxic to Cu sol. BC xxi 321. 1904 Electrodes for conductivity of tissue. ZB (nf) xxv 280. 1905 Water content of emulsoid particles. ZPC xliv 461. 1906 Bioelectric currents. ZAP vi 99. Gallardo 1906 Model of mitosis. CRA cxlii 228. Ganter 1912 Temperature coefficients. AGP cxlvi 185. 208 LITERATURE LIST Gardiner, W. 1884 Pores in plant cell walls. PT clxxiv 817. 1897 Surface movements of dividing eggs. Jour. of Morph. xi 55. Garmus a oo permeability of gland cells during activity. ZB : viii 185. Garten 1906 Time of appearance of current of injury. ZP 673. 1909 Rhythmic response with single stimulus, ZB lii 534. tgit Electric organ. VGDN 1. ‘ Garrey 1913 Resistance of fish to change in medium. AJP xxxix 313. 1915 A of animals and solutions. BB xxviii 77. Gaskell 1886 Positive variation of heart during vagus inhibition. JP vii 451. Gassner 1906 Pos. and Neg. galvanopropism of roots. BZ lxiv 149. Gasser & Loevenhart 1914 Respiratory center and asphyxia. JPET v 2309. Gatin-Gruzewska 1904 A of glycogen = 0. AGP ciii 282. —— & Biltz 1904 Ultramicroscopy of albumin. AGP cv 115. Gerassimow 1902 Cell nucleus ratio. ZAP i 220. Ghiron 1913 Dyes filter through glomeruli. AGP cl 405. Gibbs 1874-8 Surface tension and adsorption. TCA iti 380. Gibson & Titherly 1908 Photoelectricity and photosynthesis, AB xxii 117. eee 1913 Polarizability of skin and psychogalvanic reflex. MMW 2389. 1915, Psychogalvanic reflex. AGP clxii 480. Girard 1908-13 Negative osmose and electroendosmose. CRA cxlvi 927; cxlviii 1047, 1186; cl 1446; cliii 4o1; clvi 1401. 1910 Negative osmose and turgor. JPP xii 471. 1913 Hemolysis and electroendosmose. CRB Ixxiv 520. Glaser 1912 Calorimetry of embryos. S xxxv 189. 1913 Parthenogenesis. S xxxviii 446. 1914a Parthenogenesis. BB xxvi 387. 1914b Shrinkage of egg on fertilization. BB xxvi 84. 1915 Fertilization. BB xxviii 149. Gothlin 1902 Saline for frog’s heart. SAP xii 1. Goldschmidt 1899 Catalytic reaction in diphasic system. ZPkC xxxi 235. —— & Pribram 10909 Lipoids precipitated by anaesthetics. ZET vi 1. Goodridge & Gies 1911 Edema. SEBM viii (106). Gortner & Harris 1913 A of plant juices. BTBC xl 27. 1914 Cryoscopic method. PW xvii 40. Gotch & Laws 1885 Limulus blood ash. 54 Meeting Brit. Assn. 774. Gouy 1906 Lyotrope series and surface tension. ACP (8) ix 75. Graham 1854 Negative osmose of acids reduced by salts. PT cxliv 177. . 1861 Colloids and rate of diffusion. PT cli 183. Gray 1913a Increased conductivity of egg. PCPS xvii 1. 1913b Increased conductivity of egg. JMBA x 50. 1915 Agglutination of sperm with ions. QJMS Ixi 119. Greely 1904 Galvanotropism. JP vii 3. Greene 1904 A of salmon. BBF xxiv 4209. 1909 A of salmon. BBF xxix 129. 1910 A of salmon. JEZ ix. Griffiths 1892 “Physiology of Invertebrata.” London. Grijns 1896 Hematocrit and osmotic pressure. AGP Ixiii 86. Grode & Lesser 1913 Crushing liver greatly increases splitting of glyco- gen. ZB 1x 371. Gros 1910 Adsorption of NH, and hemolysis. BZ xxix 350. 1910 Neuraxons require 6 times as much anaesthetic as for general anaesthesia. AEP lxii 379. 1912 Local anaesthetics are effective on all cells. AEP Ixvii 132. 3 Griinwald 1909 Chloride starvation has same effect on nervous system as bromide poisoning. AEP 1x 360. : LITERATURE LIST 209 Griitzner 1893 Myelin sheath inhibits diffusion. AGP liii 115. 1894 Lyotrope series and excitability of nerve. AGP lviii 60. Grumbach 1911 Anesthetics and contact potentials. ACP xxiv 463. Guldberg & Waage 1879 Law of mass action. ZPC cxxvii 69. Pe Dissociation and isomerism of uric acid. ZPC 1x 25, 38; X1ii 253. 1909b Diffusible uric acid in serum. ZPC Ixiii 466. 1913 Colloidal solutions of uric acid. ZPC Ixxxix 253. Guthrie 1914 Hypertonic laking.§ PSEB xi 149. —— & Ryan 1910 Action of Mg. AJP xxvi 320. Guye 1910 Association of H.O. TFS vi 8. Haber 1908 Solution tension and polarization. APk (4) xxvi 927. —— & Klemensiewicz 1909 Concentration cells with membranes permeable only to H ions. ZPkC Ixvii 385. Haberlandt 1890 Geotropism of plants. BDBG xviii 261. Hijesiand 1915 Hay acids inhibit yeast more than calculated from PH. xix 181, Hagan & Ormond 1912 Vagus action on heart abolished with pure NaCl solution. AJP xxx 105. Haldane 1892 Blood-gas apparatus. JP xviii 419. —— & Priestly 1905 .2% rise in alveolar CO, doubles lung ventilation. JP xxxii 225. Halliburton 1916 Physiological Abstracts. London. i—. Hallwachs 1888 Photoelectricity. APk xxxiii 301. Hamburger 1890 Plasmolysis. ZPC vi 311. 1892 CO, causes Cl to pass from plasma into corpuscle. ZB xxviii 405. 1893 Hematocrit and osmotic pressure. ZP. 1896 Absorption from peritoneum increased by pressure. AAP 302. 1898a Hemolysis with acids. AAP xxxi. 1898b Diffusible and non-diffusible alkali in serum. AB 1. 1899 Protoplasm not a solution. AAP. ae eons Druck und Ionenlehre in der Med. Wiss.” Wies- aden. 1908 Negative osmose through double membrane. BZ xi 443. 1912 “Untersuchungen ueber Phagocyten.” Wiesbaden. Bergmann. 1915 Micro-analysis of K. BZ 1xxi 415. 1915 Phagocytosis. IZPB ii 245, 249, 255. 1916a Ca, anesthetics, CO, and lack of oxygen increase phagocytosis. 1916b Erythrocytes permeable to Na and K. WMM Ikxvi 521, 575. —— & de Haan 1g10 Effect of salts on phagocytosis. BZ xxiv 304. 1913 Solubility, surface tension, toxicity and narcotic power. AAP 77, —— & Hekman 1908 Phagocytosis. BZ ix 275. — & Van Lier 1902 CO, causes NO’; and SO”, to pass into erythrocyte. AAP 402. Hamill 1906 Antitrypsin. JP xxxiii 476. Hammersten, Hedin & Mandel 1914 “Text Book of Physiological Chem- istry.” 7th Ed. N. Y. Handowsky 1910 Hydrolysis of alkali albuminate. BZ xxv 510. 1912 Partial hemolysis. AEP Ixix 412. Harden & McLean 1011 Cell oxidation. JP xliii 417. Hardy 1899 Structure of emulsoid coagulum and protoplasm. Precipita- tion of sols with H’. JP xxiv 158, 301. 1900a Solution. JPC iv 235, 254. 1900b Isoelectric point = least stability, and precipitation by opposite charge. ZPkC xxxiii 385. 1905 Isoelectric point of proteins. JP xxxiii 251. —— & Whitham 1899 Coagulation of protein by electricity. JP xxiv 288. 210 LITERATURE LIST Harkins & Humphrey 1916 Stalagmometer corrections. JACS. Harlow & Stiles 1909 Shaking enzymes. JBC vi. Harris 1914 Acid soils due to negative colloids. JPC xviii 355. Harris, J. & Gortner 1914a Conversion table for A. AJB i 75. 1914b Conversion table for A. BCB iii 259. Ig1sa A and conductivity of plant juices. BCB iii 196. 1915b A and conductivity of plant juices. BCB iv 52. Harrison 1910 Neuraxon growth and ameboid motion. JEZ ix 787. Hartridge 1912 Color vision. JP xlv (p. xxix). Harvey 1910a Fert. Mem. imperm. to sugar and proteins. JEZ viii 355. 1910b Parthenogenesis (Review). BB xviii 260. 1911 Cell permeability. JEZ x 508. 1912 Permeability of artificial cells. BCB ii 50. 1913 Indicator method and permeability. AJP xxxi 335. 1914a Fertilization membrane. BB xxvi 237. 1914b Permeability to acids. IZPB i 463. 1914c Permeability to alkali. CIWP (no, 183) 131. 1915a Photogenesis. JACS xxxvii 306. 1915b Photogenesis. AJP xxxvi 230. 1916 Photogenesis. S xliv 208; 652. Hasselbalch 1911 H,-electrode. BZ xxx 317. : 1912 PH and respiratory center. BZ xlvi 413. 1913 Improved H.-electrode. PH .17 lower at 18.9° than at 37°. BZ xlix 447, 451. — & Gammeltoft 1915 PH of blood. BZ Ixviii 206. — & Lundsgaard 1912 PH of blood. BZ xxxviii 77. Hatschek 1910 Ultrafiltration. KZ vii 81. 1911 Viscosity of emulsoids due to swelling. KZ viii 34. 1913 Volume of disperse phase in emulsions. KZ xii 238. Hauberisser & Schoenfeld 1913 Effect of salts on swelling of tendons. AEP Ixxi 102. Haycraft 1883 Hirudin. AEP xviii 209. Heald 1896 Electrolytic solution tension and toxicity. BZ xxii 125. Hedin 1891 Hematocrit. SAP ii 134. 1895 Hematocrit and osmotic pressure. AGP Ix 360. 1895 Hematocrit and osmotic pressure. AGP Ix 360. 1898 Permeability of erythrocytes. AGP Ixx 525. 1899 Rate of diffusion through dead gut. AGP Ixxviii 205. 1906 Enzyme action inhibited by adsorption of enzyme. BJ i 484. 1909 Adsorption of colloids irreversible. ZPC 1x 364. - Heidenhain 1872 Blood pressure and formation of lymph. AGP v 309. 1894 Negative osmose through gut wall. AGP lvi 579. ; Heilbrunn 1913 Membrane elevation due to decreased surface tension. B xxiv 343. 1915a Development and gelatin of egg. BB xxix 149. 1915b Oxidation in egg. S xlii 615. Heimrod 1913 Supposed ¢atalytic action of oscillating magnetic field. ZAC xix 812. ; Hekma 1915 Blood coagulation. IZPB ii 279, 290, 352. Heller 1911 A of blood rapidly increases after nephrectomy even in starv- ing rabbit. ZP xxv 375. Hemptinne 1898 H in atomic form in Pd. ZPkC xxvii 420. Henderson 1907 Formula for diffusion potential. ZPkC lix 118. Henderson, L. 1908 Buffers. AJP xxi 173. 1909 Dissociation of CO... EP viii 254, 274, 316. i910 PH of urine. BZ xxiv 4o. 1911 Kidneys regulate PH of blood. JBC ix 403. 1913 “The Fitness of Environment.” Macmillan. LITERATURE LIST 211 — & Bloch 1908 Buffer value of CO, AJP xxi 420. — & Spiro 1908 Buffer value of urine. BZ xv 105. Henderson, V. 1910 Antitoxic action of sugar. ZP xxiv 5109. Henderson, Y., Palmer & Newburgh H’ and colloid swelling. JPET v 449. Henri 1904 Erythrocytes anodic. CRB lvi 866. ‘Ig11 Photochemistry of sight. JPP xiii 841. ? — & Lalou 1903 A of shark changes with sea water. CRA cxxxvii 721. —— & Mayer 1904 Adsorption potential. CRA cxxix 974. Henze 1910 Increased O, increases respiration of coelenterates, BZ xxvi 255. 1913 Blood corpuscles of acidians are acid. ZPC lxxxvi 340. Herbst 1893 Artificial production of fertilization membrane. BZ xiii 14. 1898 OH’ necessary for egg development. AE vii 486. 1904a Na, K, Ca, Mg, Cl, SO,, HCO;, and OH necessary development of sea urchin egg. AE xvii 306. 1904b Ca-free water causes cells to fall apart. AE xvii 440. Herlitzka 1912 Addition of urea, glycerine, arctameide, chloral hydrate or urethane improves Ringer’s fluid. AF x 261. Hering 1915 KCI stimulates vagus center. AGP clxi 537. Herzog 1902 Zymase action is autocatalytic. ZPC xxxvii 149. & Betzel 1911 CHCl, and AgNO, adsorbed by yeast but formaldehyde chemically combined. ZPC Ixxiv 221. —— & Kasarnowski 1908 Crystalloids diffuse more than I9 times as fast as colloids. BZ xi 172. —— & Meier 1909 Asymmetry and enzyme action. ZPC lix 57. 1911 Oxydases. ZPC Ixxiii 258. Hess 1913 Infant gastric juice. AJDC vi 264. Heubner 1905 Viscosity of blood. AEP liii 280. Heymans 1912 Permeability of filter ultrafilter and membranes to mi- crobes. AIPd xxii 49. Higgins 1913 CO, (Plesch, 20 sec.) 20% higher than Haldane. CIWP (No. 203) 171. —— & Means 1915 Alv. CO, in acidosis. JPET vii 1. Hill, A. 1898 Synthesis of isomaltose. JCS xxiii 634. 1903 Enzymatic splitting and synthesis of sugars. JCS Ixxxiii 578. Hill, A. V. 1910 Formula for Nernst’s theory of stimulation. JP xl 190. 1912 Nerve impulse produces no heat. JP xliii 433. 1913a Half of heat of muscle produced during contraction; half dur- ing restitution. JP xlvi 28, 435; xlvii 305. 1913b Dissociation of oxyhemoglobin. BJ vii 471. 1914 Oxidation of lactic acid. JP xlviii (p. x). 1915 Formula for blood-gas apparatus. JP 1 (vii). — & Weizsicker 1914 Myothermic apparatus. JP xlviii (p. xxxv). Hill, L. & Nabarro 1895 Not always more CO, in venous blood from active organ (vascular dilatation). JP xviii 220. Hirokawa 1908 Swelling of pores of kidney due to urine. AF xi 458. 1909 Effect of salts on spermatozoa, BZ xix 201. Hirschfeld 1907 HgCl, may lake erythrocytes. AH Ixiii 275. 1909 Ameboid motion. ZAP ix 529. Hirschfelder 1911 Electrocardiogram. Inters. Med. JI. xviii (6). His & Paul 1900 Dissociation of uric acid. ZPC xxxi 1, 64. Hober 1899 Rate of diffusion and adsorption by gut. AGP Ixxiv 225, 246. 1900 PH of blood. AGP Ixxxi 522. 1903a Selective adsorption of iron by gut (other heavy metals ab- sorbed less). AGP xciv 337. 1903b PH of blood. AGP xcix 572. 1904a Erythrocytes and yeast are anodic; changed by polyvalent ions, impermeable to Na’, K’, NH,', Ca” and Mg’i. AGP ci 607, cii 196. 212 LITERATURE LIST 1904b A of fresh water animals. AGP cii 199. 1905 Alkali salts increase permeability of muscle. AGP cvi 599. 1907 Current of injury reduced by anaesthetics but caused by toxic dose of anaesthetics. AGP cxx 492. 1907 Inverse lyotrope series for positive and negative proteins and irregular series for neutral proteins. Series for lecithin, BCPP xi 35. 1908a Hemolysis and lyotrope series. BZ xiv 2009. 1908b Physikalische Chemie d. Blutes und. Lymphi. Oppenheimer’s Handb. d. Biochem. II 2, 1. 1909a Theory of skin current. ZEC xv 510. 1909b Effect of salts on cilia. BZ xvii 518. 1909c Dispersion of dyes. BZ xx 56. 1909d Permeability of erythrocytes. ZPC Ixx 134. 1910a Conductivity of cell interior, AGP cxxxiii 237. 1910b Effect of organic anions on cells. AGP cxxxiii 311. 1g910c Alkali salts increase permeability of muscle. AGP cxxxiv 316. 1giod Stimulation. ZAP x (Ref.) 173. 1912a Lung is permeable to NH;. AGP cxlix 87. 1912b Conductivity of cell interior. AGP cxlviii 180. 1913a Muscle contraction. ZEC xix 738. 1913b Increase of conductivity of blood with increased alternations of current. Cond. of interior of muscle fibre. AGP cl 15. 1913c Bleaching of wool-violet by protoplasm. ZB xlviii 201. 1914 “Physikalische chemie der Zelle und der Gewebe.” 4th ed. Leipsic. . — & Jankowsky 1903 PH of urine. BCPP iii 525. — & Kempner 1908 Kidney cells absorb all dyes but suspensoids. BZ xi 105. —— & Konigsberg 1905 Dyes excreted by frog’s kidney carried in pre- formed granules. AGP cviii 323. — & Nast 1914 Saponin hemolysis and lyotrope series. BZ Ix 131. —— & Spaeth 1914 Rare earths on muscle. AGP clix 433. —— & Waldenberg 1909 Effect of organic ions on cells. Position of Cs in lyotrope series. AGP cxxvi 331. Hoffmann 1889 Buffer value of proteins. ZIM x 793, x 521. 1914 Haptogen membranes and emulsions, Collection of particles at surface. ZB Ixiii 386. Hofmeister 1888 Hofmeister series. AEP xxiv 247. 1891 Hofmeister series. AEP xxviii 210. Hoitsema 1895 Hydrogen in atomic form in Pd. ZPkC xvii 1. Hooker 1911 Ions and CO, on vascular tone. AJP xxviii 361. 1912 Effect of CO, and O, on vascular tone in the gut. AJP xxxi 47. Howe & Hawk 1912 PH of feces. JBC xi 120. Howell 1914 Blood coag. AJP xxxv 143, AIM xiii 76. —— & Duke 1908 Vagus inhibition and KCl. AJP xxi 51. Howland & Marriott 1916a Acidosis and diarrhea. AJDC xi 300. 1916b Alv. CO, and acidosis. JHHB xxvii 63. Hoyler 1907 Autocatalytic action of H:. ZPC 1 404. Hudson 1908 Invertase action. JACS xxx 1160, 1564. 1910 PH and invertase. JACS xxxii 1220. Hitfner 1903 Dissociation of oxyhemoglobin. AAP 217. — & Gansser 1907 Osmotic pressure of hemoglobin. Mol. wt. = 16321. P 200. Huenekens 1914 Effect of diet on PH of infant’s stomach. KZ xi 207. Hughes, A. L. 1914 “Photo-Electricity.” Cambridge U. Press. Hulett 1901 Surface tension and solubility. ZPkC xxxvii 385. 1903 Osmotic pressure and capillarity, tensile strength of water. ZPkC xlii 353. LITERATURE LIST 213 Hutchinson 1915 Resistance of Paramecium. JEZ xix arr. Hyde 1904 Action current of cell division. AJP xi 52. —— & Spreier 1915 Light and development. AJP. Hyman 1916 HCN and oxidation. AJP xl 238. Iscovesco 1910a Catalase cathodic. Pepsin anodic. BZ xxiv 53. 1910b Surface tension of emulsions. CRB 1xix 537. 1910c Cholesterin inhibits action of soap and lecithin by combining : with them. CRB lxix 566. Ishizaka & Loewi 1905 Ca antitoxic to muscarin. ZPk xix 593. ° Itami & Pratt 1909 Oxidation and cell structure. BZ xviii 303. Jackson 1915 Growth of organs of rat. JEZ xix 99, AJA xviii 75. Jacobs 1909 Dessication of rotifers. JEZ vi 207. Jacoby 1910 Enzymes of egg and sperm. BZ xxvi 336, 536. —& Coa 1908 Precipitate of caffein in muscle. AEP lix (sup) Jahnson-Blohm 1913 Enzymes displaced from surface by anaesthetics and saponin; and activity restored by the latter. ZPC Ixxxii 178. eugene ama of exudates inhibited by anaesthetics. WKW 0. 20). Jennings 1904 Tropisms. CIWP (No. 16). 1906 “The Behavior of the Lower Organisms.” Columbia U. Press, 1914 Paramecium swims backward consinuously in stimulating solu- tion. JCNP xiv 442. Jensen & Fischer 1913 Hydration in muscle. ZAP xiv 320. Joel 1915 vee retard increase in conductivity of erythrocytes. xlxi 5. Johannsen 1906 Etherization causes lilacs to sprout earlier. “Das Aether- verfahren beim Fruehtreiben.” Jena. : Johnston 1916 CO, in water. JACS xxxviii 947. ; Jones, H. 1897 “Freezing Pt. Boiling Pt. and Conductivity Methods.” Easton, Pa. 1907 Hydrates in solution. CIWP (No. 60). Jones, W. 1913 Surface tension of solids. ZPkC Ixxxii 448. Jordan 1913 “Vergleichengle Physiologie Wirbelloser Tiere.” Jena. Jordis 1908 Colloids are electrolytes. KZ ii 361, iii 13. Jorissen & Woudstra 1911 Beta rays coagulate positive sols. KZ viii 8. Joseph & Meltzer 1911 Abolition of irritability with Ca and restoration with Na. AJP xxix 1. —— & Austin 1900 Toxicity and ionization. JPC iv 76. — & True 1891 Toxicity of Cu ions. BG xxii 81. 1896 n/6400 H’ toxic. JAMA xxvii 138. Kanda 1914 Reversibility of geotropism. AJP xxxv 162. 1916 Geotropism. BB xxx 57. Kanitz 1903 H’ and invertase. AGP c 547. 1906 Dissociation of amino acids. ZPC xlvii. 1907 Dissociation of tyrosine and phenylalamine. AGP cxviii 539. 1915 Temp. Coef. of respiration. IZPB ii 272. Kastle 1910. Oxidases. BHL (No. 59). — & Loevenhart 1900 Synthesis of fat by pancreas lipase. ACJ xxiv 4o1. 1903 HCN may hasten catalysis. ACJ xxix 397. 1907 Synthesis of fat by pancreas lipase. JBC ii 427. Katy 1896 Salts in frog’s muscle. AGP Ixiii 1. Katzenellenbogen 1906 Permeability of the gut. AGP cxiv 522, Kaufler 1903 Surface tension and osmotic pressure. ZPkC xliii 686. Keith, A. & Flack 1907 Conduction in heart. JAP xli 172. Keith, N., Rowntree & Garaghty 1915 Blood volume. AIM xvi 547. Kidd 1916 CO, inhibits cell respiration. PRS (B) Ixxxix 136. 214 LITERATURE LIST Kirsch 1912 Surface tension of solutions increasing permeability of yeast to invertase = .5. BZ xl 152. 1912 Surface tension of cells. BZ xl 152. Kite 1913 Permeability of protoplasm. BB xxv 1. Knoblach 1901 Charge of colloids. ZPkC xxxix 225. Knipffer & Bredig 1898 Temperature and direction of reaction. ZPkC Xxvi 255. Knowlton 1911 Addition of gelatine to blood decrease secretion of urine. Starch solution not effective. JP xliii 219. Koch & McLean 1910 Anaesthetics and size of lipoid particles. JPET ii 249. Kodis 1898 Undercooling of muscle. ZP xii 593. 1901 Conductivity of dying muscle. AJP v 267. Kohler 1904 Ultra violet microscopy. ZWM xxi 129, 273. Koelichen 1900 Polymerization in concentrated solution only. ZPkC XXXili 129. 1895 Hematocrit and osmotic pressure. AAP 154. Koeppe 1897 Erythrocytes increase ionization of CO, and HCO,’ ex- changed for Cl’ of serum. AGP Ixvii 180. 1900 Physikalische Chemie in der Medizin. Wien. 1905 Erythrocytes in hematocrit appear laked. AGP cvii 183, 187. Kohlrausch 1907 Speed of ions. ZEC xiii 333. — & Heydweiller 1894 Conductivity of H.O = .0000385 at 18°. ZPkC xiv 317; APk liii 2009. Koltzoff 1908 Swelling of spermatozoa. AZ ii 1. 1912 Effect of salts on contractile stalk of Zoothamnium. AGP cxlix 327. 1914 Optimum PH for phagocytosis. JZPB i 82. Koopman 1915 Enzymes. JZPB ii 266. Konikopf 1913 PH of blood. BZ li 200. Koranyi, Von 1897 A of blood varies with CO.. ZKM xxxiii 1. Kovacs 1902 A of blood varies with CO.. BKW xxxix 362. Kozawa 1914a Hemolysis greatest at isoelectric point. Reversal of cata- phoresis. PH of H.PO, + NAH.PO,. BZ Ix 146. 1914b Permeability of erythrocytes to sugar. BZ 1x 231. Krafft 1896 Soaps are colloids. BDCG xxix 1328. Kreibich 1910-1 Hg does not markedly affect PH of blood. WKW xxiii 355 XXIV. Krogh 1904 CO, tension of sea water. Meddelelser om Grénland, xxvi 333. Copenhagen. 1908 Micro-tonometer. SAP xx 250, 270. = 1910 Absorption of O, and CO, by water. SAP xxiii 224. 1910 Blood gas exchange in lungs. SAP xxiii 248. 1914 Temperature coefficient of development. ZAP xvi 163, 178. —— & Krogh 1910 CO, and O., tension of arterial blood. SAP xxiii 179. Kuehne 1864 Violet cells of Tradescantion become red at anode and green at cathode (due to metal electrode). “Untersuchungen ueber das protoplasma und die Contractilitaet.” Leipsic. Kiister, E. 1910 Formation of plasma membrane. ZBt ii 689; AE xxx 351. 1911 Plant cells absorb many sulfonic acid dyes. JWB 1 261. 1913 Liesegang’s rings. KZ xiii 1092. Kiister, F. 1894-5 Adsorption formula. ZPkC xiii 445; AC cclxxxiii 360. Kyes 1902 Cobra hemolysin activated by lecithin. BKW 886. Lachs & Michaelis 1911 Adsorption of NaCl not antagonized by non- electrolytes. KZ ix 275; ZEC xvii 1. Landolt-Boernstein-Roth 1912 Physikochemische Tabellen. 4th Ed. Berlin. Landsteiner 1913 Blood shadows precipitate at isoelectric point. BZ 1 176. LITERATURE LIST 215 —— & Jagec 1904 Precipitation of emulsoids with suspensoids; adsorption compounds of immune bodies. MMW (No. 27). Ss & Uhlirz 1905 Adsorption of colloids irreversible. ZB xl 265. ; Lapique 1909 Nernst’s theory of stimulation. CRA cxlix 871; JPP xi 1009, 1035. —& te 1913 Diameter of neuraxon and conduction. CRA clvii 1163. , Laquer & Sackur 1903 Viscosity of casein increased by acids and alkalis. BCPP iii 193. Leathes 1895 A of lymph greater than blood. Infusion of hypertonic NaCl increases blood volume. JP xix 1, 418. LeBlanc 1913 No Tyndall phenomenon of sugar solutions. ZEC xix 794. Lee 1903 Alcohol increases rhythm of medusa. AJP viii (p. xix). —— & Salant 1902 Alcohol and muscle, AJP viii 61. Lehmann 1884 Mice and frogs die in compressed oxygen. Oxidation of pyrogallol independent of O, pressure. AGP xxxiii. Lepeschkin 1908 Light increases permeability of plant cells. BDBG xxvi (a) 198, 231, 724. 1910 Plasma membrane and Traube’s membrane are sols. BDBG XXViii 383. I91t Composition of plasma membrane. BDBG xxix 247. Lesser 1907 Effect of temperature on skin current. AGP cxvi 124. Levy, Rowntree & Marriott 1915 Indication method for blood. AIM xvi 3. Levy & Rowntree 1916 Buffer value of blood. AIM xvii 525. Lewis, G. 1906 Color change of Co or Cu solutions due to hydration of ions. ZPkC lvi 223. 1908 P = 12.06 A — .o2t A? JACS xxx 668. —— & Keyes 1912 Sol, Ten. of K and Li. JACS xxxiv 122. — & Lacey 1914 Ex Cu = —.3347. JACS xxxvi 804. — & Randall 1914 Free energy of H. JACS xxxvi 10609. —— & Rupert 1911 Solution tension of Cl. JACS xxxiii 299. Lewis, M. 1916 Sea water as culture medium. AR x 287. Lewis, W. 1908 Haptogen membranes. PM (6) xv 499. 1909 Surface tension between oil and water. PM (6) xvii 466. Electric charge of oil drops in water. KZ iv ait. 1910 Surface tension between liquids, adsorption of NaCl. ZPkC Ixxiii 129. Lewites 1907 Swelling of gels. KZ ii 166. Liebreich 1890 Surface films and chemical reaction. ZPkC v 529. Liesegang, R. 1911 Liesegang’s rings. AE xxxiii 328. L’Hermite 1855 Permeability by solution in membrane, ACP (3) xliii 420. Lillie, F. 1913 Acids cause aggregation and alkalis agglutination of sperm. JEZ xiv 515. Lillie, R. S. 1902 Oxidation at nucleus. AJP vii 412. 1903 Spermatozoa are electronegative. AJP viii 273. 1905 Model of mitosis, AJP xv 46. 1907 Osmotic pressure of proteins reduced by salts and increased by H’ and OH’. AJP xx 127. 1908 Heat-Parthenogenesis. JEZ v 375. 1909a H’ produces polarization of plasma membrane. Lyotrope series and cytolysis, MgCl, decreases permeability. AJP xxiv 14, 36. 1909b Artificial parthenogenesis and permeability. BB xvii 188. rgo9c Effect of salts on cilia. AJP xxiv 450. 1910 Lyotrope series, cytolysis and parthenogenesis. AJP xxvi 106, 126. 1g911a Permeability, stimulation and contraction. AJP xxviii 197. 1g1tb Fertilization. BB xxii 328. 216 LITERATURE LIST 1912a Anaesthetics may increase size of lipoid particles in plasma membrane by dissolving in them. AJP xxx 372. 1912b Anaesthetics decrease toxicity of pure NaCl, AJP xxx 1. I913a Anaesthetics inhibit increase in permeability. AJP xxxi 255. 1913b Oxidation in blood cells increased by induction shocks. JBC XV_ 237. . 1913c Cell division. JEP xv 23. 1914a Rate of conduction. AJP xxxiv 414. 1914b Anaesthetics vs, salts. JEZ xix 591. ro14ce Cell narcosis. JBC xvii 12r. 1o14d Stimulation and permeability. PSM 570. 1916a Fertilization increases permeability of egg to water. AJP xl 249. 1916b Rate of nerve impulse varies as electric conductivity of medium. AJP xli 126. _ Ig16c Anaesthesia. BB xxx 311. Linder & Picton 1895 Antagonism of cations in precipitation of sols. Elec- tric charge, dispersion and freezing out of colloids. JCS Ixvii 63, 73. 1897 Al.(OH), and Fe.(OH), sols are electro-positive. Conductivity of suspensoids same as water. Mutual precipitation of sols of opposite sign. JCS Ixxi 568, 572. 1905 Ultramicroscopy of coagulation. JCS |xxxvii 1911. Lipscomb & Hulett 1916 Electrolytic calomel. JACS xxxviii 20. Locke 1900-1 Locke’s solution. ZP xiv 670, xv 490. Lodholz 1913 All or none law. ZAP xv 269. Loeb, J. 1889 Heliotropismus der Tiere. Wirzburg. 1897 Stimulating current must run longitudinally in nerve. AGP Ixvii 483, Ixix 99. 1898a Swelling of muscle. AGP Ixix 1. 1898b OH’ necessary for egg development. AE vii 631. 1900 Artificial parthenogenesis. AJP iii 135. 1902 Toxicity of Na’ and antitoxin action of bivalent ions. AJP vi 4II. 1903 Toxicity of sugar. AGP xcvii 304. 1906 Ca"’, Sr’ and Ba” cause rhythmic contraction of center medusa. JBC i 427. 1907 Antitoxic action of Cai’ on Na’ in cytolysis of sea urchin eggs. Z v 351. ; 1o11a Fundus eggs live in distilled water. AE xxxi 654. 191tb Antitoxic action of Ca” and Sr’ on K’ and Ne’ and of Na’ on K’, BZ xxxi 450; xxxii 155, 308. 1912a Toxicity of sugar. JBC xi 415. 1912b Increased permeability to water. BZ xlvii 127. 1913 Artificial Parthenogenesis and Fertilization. Chicago. 1914a “Fertilizin” not necessary for fertilization. JEZ xvii 123. 1914b Bunsen-Roscoe law and phototropism. ZP xxvii 80, 1915a Salts antitoxic to acids. JBC xxiii 139. 1915b Ca and permeability. JBC xxiii 423. 1916 Phototropism. JEZ xx 217. ——& Budgett 1897 Galvanotropism. AGP Ixv 518. —— & Beutner 1912 Current of injury in plants. BZ xli 1, xliv 303. 1913 Current of injury. BZ li 288. 1914 Bioelectric currents. BZ lix 2or. —— & Cattell 1915 Antagonism of salts. JBC xxiii qr. —— & Ewald 1916 Chemical stimulation of nerve. JBC xxv 377. —— & Gies 1902 Toxic and antitoxic action of ions. AGP xcili 246. —— & Wasteneys 1910 Oxidation in egg. Medusae anaesthetized by Mg use more O,. BZ xxviii 340, 350. LITERATURE LIST 217 To11a Bases and alkaline salts increase oxidation. BZ xxxviii 410. 1g11b Bromide intoxication of fish. BZ xxxix 185. 1912a Adaption to heat. JEZ xii 543. 1g12b Heart rhythm reduced by reduction of O, BZ xl 277. 1913 Anesthetics reduce cell division more than oxidation. JBC xiv 517. Ig15a Effect of poisons on A of Fundulus. JBC xxi 223. 1915b Osmotic pressure of cell. JBC xxiii 157. 1915c Phototropism. JEZ xix 23. Loeb, L. 1901 Phagocytosis. AGP cxxxi 465. Loeb, W. & Higuchi 1910 PH of serum of placenta. BZ xxiv 92. Loew 1889 Synthesis of sugar from formaldehyde. BDCG xxii 470. . 1892 Antagonism of Ca and Mg. F 368. Loewe, F. 1912 Water interferometer. KZ xi 226. Loewe, S. 1912 Methylene blue adsorbed by lecithin (in chloroform). BZ xlii 150-218, 1913 Anesthetics reduce conductivity of artificial lipoid membranes. BZ lvii 161. Loewy 1894 Alkali albuminate more concentrated in corpuscle than in serum. AGP lviii 462. —— & Zuntz 1894 CO, increases diffusible alkali in serum. AGP lviii 511. Loomis 1894 A of NaCl. APk li 515. 1897 A of NaCl. APk ix 527. — & Acree 1911 Calomel electrode. ACJ xlvi 585. Lorant 1914 Surf.-Ten. between Liquids. AGP clvii 211. Lorenz & Boehi 1909 Dissociation of water. ZPkC Ixvi 740. Lottermoser 1907 Adsorption by filters. ZPkC 1x 458. 1908 Freezing out of colloids. BDCG xli 3976. 1910 Peptization and reversal of charge of sols. KZ vi 78. —— & Rothe 1908 Impurities of sols necessary for stability. ZPkC Ixii 359. Lowenherz 1896 Influence of alcohol on dissociation of water. ZPkC xx 283. Lubs & Clark 1915 New indicators. JWAS v 609. Lucas 1909a Temperature coefficient of nerve conduction. JP xxxvii 112. 1909b Rise of neg. var. prop. to rate of transmission. JP xxxix 207. Igogc All or none law. JP xxxviii 113. . Ludwig 1849 Swelling of colloids. ZRM viii. Ludloff i895 Galvanotropism due to reversal of cilia at cathode. AGP lix 523. Lunden 1908 Ampholytes. JBC iv 267. Lundsgaard 1912 PH of blood. BZ xli 247. Lusk 1912 “The Elements of the Science of Nutrition.” 3rd Ed. Phila. 1915 Influence of food on metabolism. JBC xx 555 (and p. viii). Luther 1896 Adsorption potential of colloids. ZPC xix 529. —— & Forbes 1909 Photochemistry. JACS xxxi 770. Lyon 1898 Otocyst. JCNP viii 238. 1901 Rhythmic production of CO, and sensibility to heat and cold (eggs). AJP xi 52. 1902 Cell division and rhythmical susceptibility to KCN. AJP vii 56. 1903 Artificial parthenogenesis, AJP ix 308. 1904 Rheotropism. AJP xii 147. 1905a Geotropism. AJP xiv 42r. 1905b Density of eggs. AJP xxiv 244. 1906 Geotropism. BB xii 21. 19092 Rheotropism. AJP xxiv 244. 1909b Catalase and fertilization. AJP xxv 199. 218 LITERATURE LIST —— & Shackell to10a Autolysis and fertilization. JBC vii 371. 1910b Fertilization and permeability. S xxxii 240. Macallum 1904 Blood salts same as Cambrian sea, Trans. Can. Ins. , 1905 Microanalysis of K. JP xxxii 95. 1908 Microanalysis. EP vii 552. tg11 Surface tension. EP xi 505. 1912 Surface Tension and Vital Phenomena. Toronto Univ. Press (Physiol.) No. 8 1913 Muscular energy. JBC xiv (p. ix). ——— & Benson 1909 A of urine may be as low as .07. JBC vi 87. McCallum 1905 Regeneration in plants. BG. McCaskey 1908 Viscosity of blood. JAMA li 1653. McClendon 1907 Removal of chromatin from eggs with “mechanical hand.” BB xii 141. 1908 Chromatin unnecessary for cell division. AE xxvi 662. 1909a Conduction of excitation in ameba. “Mechanical hand.” JEZ vi 85 (Plate I). 1909b Nucleus is such as may act as statocyst in geotropism of para- mecium. JEZ vi 87 (Plate II). 1909c Resistance of cell structure to centrifugal force and separation of phases of different density. AE xxvii 254 (Plate VI). 1909d Physical differences between cells. AJP xxiii 460. 1909e The association of lecithin with protein in the frog’s egg. AJP “ XXV IQS. 19o9f Artificial parthenogenesis produced in a variety of ways. S XXX 454. 1g10a Frog’s egg composed of 4 or more phases. AZ v 385. 1910b Protoplasm is anodic and mitotic figure comparatively rigid. AE xxxi 80. 1gloc Fertilization increases the conductivity of the egg. S xxxii 122. tg1od Fertilization decreases the sensitiveness of the egg to electroly- sis and increases its sensitiveness to hypertonic sugar solution. S xxxii 317. 1g1o0e Fertilization or artificial stimuli increases the permeability of the egg. AJP xxvi 240. tgita Fertilization membrane. S xxxiii 387. 1g1tb Electric shock causes frog’s egg to segment. S xxxiii 620. to11c Ameboid motion and permeability. AGP cxl 271. 1g12a Pure NaCl solution increases permeability of Fundulus eggs. Egg membrane or shell is freely permeable. AJP xxix 280. tg12b Artificial parthenogenesis of frogs and toads. AJP xxix 208. 1g12c Increased conductivity of tetanized muscles. AJP xxix 302. 912d Osmosis and surface tension in physiology. BB xxii 113. 1912e Alkaloids increase permeability of eggs: AJP xxxi 131. to12f Echinochrome is not a respiratory pigment. JBC xi 435. 1913a Increase in permeability of Fundulus eggs to salts. S xxxviii 280. 1913b Surface tension and cell division. AE xxxvii 233. to14a Increase in permeability of frog’s egg. S xl 70. 1914b Antagonism of salts and anesthetics. S xl 214. 1g14c Permeability-increase of Fundulus eggs to Cl’, Na’, K’, Ca and Mg". IZPB i 28. 1914d Electric charge of protoplasm. IZPB i 1509. totde Fertilization membrane. IZPB i 163. to14f Osmotic swelling of frogs. IZPB i 160. 1914g Permeability of cells. CIWP (no. 183) 123. io1sa Fertilization or electric stimulus increases permeability of frog’s egg to Na, K, Mg, Ca, Cl and SO, AJP xxxviii 163. LITERATURE LIST 219 1915b Pure NaCl solution increases permeability of fish eggs to salts, and anesthetics inhibit this change. AJP xxxvili 173. 191sc Hydrogen electrodes. AJP xxxviii 180. 40 1915d Potentiometer for hydrogen electrode. AJP xxxviii 186. 191se PH of stomach and duodenum of adult and infant. AJP XXXViii IQI. 191sf Peptic digestion occurs in infant’s duodenum. JAMA Ixv 12. 1915g¢ Pure oxyhemoglobin oxidizes a-napthol, aloin or p-phenylene diamine. JBC xxi 275. 1916a Hydrogen electrode and tonometer and conversion table. JBC xxiv 519. 1916b Colored indicator chart. MRR xxii 333. — & Magoon 1916 Combined tonometer and hydrogen electrode. JBC xxv 669. —— & Mitchell 1912 Parth. and incr. oxidation of egg caused by OH’. __JBC x 450. ; - McClintic 1912 Phenol coefficient of disinfectants. BHL (No. 82). McCoy 1903 Dissociation of CO. ACJ xxix 437. MacDonald 1905 Microanalysis of chlorides. PRS (B) Ixxvi 272, 322. McDougall 1898 Theory of muscle contractions. JAP xxxi, xxxii 193. 1908 Muscle contraction. JAP xxxii 193. McGuigan 1904 Solution tension and enzyme action. AJP x 444. MacInnes 1914 Transference no. and diffusion potential JACS xxxvi 878, 2301. McIntosh 1897 Lyotrope series. JPC i 473. Mackenzie 1910 Gravitation. Bull. Minnesota Acad. Sc. iv 385. McPhedran 1913 Hemolysis. JEM xviii 527. Magnus 1900 Capillaries permeable to proteins. AEP xliv 68. 1901 Blood volume restored after increase by transfusion. AEP xlv 210. —, Bopediaes & Leeuwen 1914 Lungs impermeable to NH;,. AGP clv 275. Manape & Matula 1913 Protein binds little Cl’ of NaCl. BZ lii 360. Mansfield 1908 Obesity and rate of resorption and circulation in-narcosis. AIPd xvii 347. 1909 Narcosis and O, solubility. AGP cxxix 69. Marc 1911-3 Adsorption-saturation. ZPkC Ixxvi 58; Ixxxi 641. 1913 Adsorption and solid solution. ZPkC Ixxxi 641. Marriott 1916 CO, tension with indicator. JAMA Ixvi 1594. Masel 1913 Acidosis in diabetic coma. ZKM Ixxix 1. Masing 1912 Permeability of erythrocytes to sugar. AGP cxlix 227. 1914 Temperature coefficient of diffusion of sugar into erythrocytes. P clvi 401. Massart 1889 Turgor regulation. AB ix 515. Mast 1911 “Light and the Behavior of Organisms.” N. Y. Wiley. 1914 Tropisms. BC xxxiv 641. —— & Root 1916 Surface tension and phagocytosis. PNAS ii 188; JEZ Xx1 ‘I. Mathews, A. 1902a Nerves lose excitability in non-electrolytes and regain it in salt solutions. S xv 492. 1902b Current of injury. AJP viii 204. 1904a Solution tension and toxicity. Fundulus egg impermeable to NaCl. AJP x 290. 1904b Oxidising anions act best in acid and cations in alkali. AJP Xi 237. 1904c Osmotic stimulation and solution tension. Ba stimulates nerve. AJP xi 455. 1908a Electrolytic solution tension and toxicity, AJP xii 419. 220 LITERATURE LIST 1905b Solution tension and precipitation of sols. AJP xiv 203. 1907a Toxicity of NH, salts due to hydrolysis. AJP xviii 58. 1907b Cell division, AJP xviii 89. 1909 Oxidation of sugar. JBC vi 3. 1914 Narcosis and residual valence. IZPB i 433. 1915 Physiological Chemistry. N. Y. Wood., —— & Longfellow 1910 Chemical theory of permeability. JPET ii 201. Mathews, S. & Brooks 1910 Action of MgSO, JPET ii 88. Matthews, D. 1916 P in sea water. JMBA xi 122. Mathison 1911 H’ stimulates vasomotor center. JP xlii 283; xli 416. to11 Effect of PH on reduction of arterial blood. JP xliii 5. Maxwell 19005 Effect of salts on cilia. AJP xiii 154. Mayenburg 1901 Turgor regulation. JWB xxxvi 381. Mayer, A. G. 1906 Pulsations of medusa (Cassiopea). CIWP (no, 47). 1914a Electrolytes and rate of nerve conduction. CIWP (No. 183) 25. 1914b Effect of temperature on animals. CIWP (No. 183) 1. 1915 Nerve conduction. PNA i 270. 1916 Nerve conduction. AJP xxxix 375. Mayer, A. d. 1902 “Garungschemie.” Mayerhofer & Pribram 1909 Diffusion of colloids. ZEP vii. —— & Stein 1910 Sugar increases permeability of gut. BZ xxvii 376. Means, Newburgh & Porter 1915 Increased Alv. CO, in infections. clxxiii 742. Meek & Eyster 1912 Positive variation of auricle after vagus stimulation. AJP xxx 271. Meigs 1908a Theory of muscle contraction. AJP xxii 477. 1908b Structure of muscle. ZAP viii 81. 1909a Heat rigor of muscle. AJP xxiv 1, 178. 1g909b Water rigor. JP xxxix 384. 1910 Swelling, and contraction of muscle. AJP xxvi Io1. 1912a Smooth muscle. QJEP v 55. t912b Structure of smooth muscle. AJP xxix 317. 1g1zc Smooth muscle not semipermeable. JEZ xiii 497. to12d Muscle permeable to KCl. JEZ xiii 520. 1g14a Clam adductor. JBC xvii 81 1914b Swelling of muscle. AGP clviii I. 1915a Phosphate membranes. AJP xxxviii 456. t915b Ash of clam muscle. JBC xxii 493. —— & Atwood 1916 KCI selectively absorbed by muscle, AJP xl 30. — & Ryan 1912 Ash of smooth muscle. JBC xi 4or. Mellor 1909 “Higher Mathematics for Students of Chemistry, etc.” 3rd . Longmans, Melzer & Auer 1905 Anesthesia with Mg. AJP xiv 361. 1908 Ca vs. Mg. ZP xxi 788. Mendel, - Gregor 1865 Mendel’s Law. VNVB iv. Mendel, L .& oe 1903 Secretion increases lymph of pancreas. AJP ix (p. xv Mendelssohn 1916 Leucocytes are pos. galvanotropic. CRA Ixii 52. Menten 1915 PH of stomach. JBC xxii 391. — & Crile 1915 PH of blood. AJP xxxviii 225. Menz 1908 Submicrons in gelatine. ZPC Ixvi 129. Merrill 1915 Exosnose from roots. AMBG ii 507. Metcalf 1905 Haptogen membranes. ZPC lii 1. Meyer, H. 1899 Theory of narcosis. AEP xlii 109. 1901 Narcosis and partition coefficient. AEP xlvi 338. 1909 Anesthetics increase permeability and cause mixing inside cells. MMW Ivi 1577. : Meyer, K. 1911 Bacterial protease. BZ xxxii 274. LITERATURE LIST 221 Meyer, L. & Cohn 1911 Water retention favored by Na and inhibited by Ca. ZK ii 360. Meyerhof 1911a Oxidation of fertilized egg greater in pure NaCl, BZ Xxxiii 291, 191Ib Thermodynamics of eggs. BZ xxxv 159-184. 1912a Thermodynamics of cells. AGP cxlvi 159. 1912b Reduction of dyes by dead cells. AGP cxlix 250. 1914a Urethane retards oxidation of fertilized more than unfertilized eggs. Anesthetics do not lower osmotic pressure of proteins. AGP clvii 251. t914b H,O, catalysis by Pt. inhibited by anesthetics, AGP clvii 307. 1915 Anesthetics and enzymes. JZPB ii 304. Michaelis 1908 Adsorption of colloids irreversible. BZ xii 26. 1908 Solution tension and polarization. ZEC xiv 353. 1909 Calculation of isoelectric point. BZ xix 181. 1912 Isoelectric point of proteins. Nernst-Festschrift. 308. 1914 “Die Wasserstoff ionenkonzentration.” Berlin. —— & Davidsohn 1910 Indicators for stomach. ZEP viii 398. 1910 Isoelectric point. BZ xxx 143. I9g1I Optimum PH for invertase. BZ xxxv 386. 1913 Gelatine stains with acid dyes in acid solution. BZ liv 323. —— & Ehrenreich 1908 Acid dyes and invertase adsorbed by clay but not by kaolin. BZ x 283. —— & Menten 1913 Action of invertase inhibited by fructose. BZ xlix 333. —— & Mostynski 1910 Viscosity and ionization of proteins. BZ xxv 401. —— & Perkins 1914 “Dynamics of Surfaces.” London. —— & Pincussohn 1906 Ultramicroscopy of colloid reactions. BZ ii 251. —— & Rona 1907 Protein precipitated by dialysed iron, BZ ii, iii, iv, v. 1g08a Osmotic compensation. BZ xiv 476. 1908b Adsorption of colloids irreversible. Competitive adsorption. Z xv 196. 1909a Competitive adsorption. BZ xvi 489. t909b Effect of salts on Congo red. BZ xxiii 61. 1910 Isoelectric point of denatured albumin. BZ xxvii 38. 1912 Isoelectric points of emulsions. BZ xxxix 481. — & Takehashi 1910 Hemolysis and isoelectric point. BZ xxix 439. Miculicich 1910 Effect of ions on hemolysis by anesthetics. ZP xxiv 523. Millikan 1910 Charge of an ion. PM xix 209. 1916 Equation for contact electricity. PR vii 18. Milroy 1914 PH and respiratory center. QJEP viii 141. Mines 1911a Ca, Mg, Sr and Ba inhibit the stimulating action of K on muscle. JP xlii 251. : Ig11b Ppt. of As.S, by cations. Action of rare earth salts on emul- soids and reversal of emf of concentration cell with gelatine diaphragm. JP xlii 309. 1911c PH of pecten blood = 6.7. Heart stops in diastole in acid, systole in alkali, JMBA ix 171. 1912 PH for heart of pecten. JP xliii 467. 1913a Action of ions. JP xlvi 188. 1913b Dynamic equilibrium of the heart. JP xlvi 349. Milner 1907 Adsorption and surface tension. PM (6) xili 96. Mitscherlich 1893 Ignition point of H,4O, raised by pressure. BDCG XXvi 399. Moltovan & Weinfurter 1904 Anesthetics reduce cell respiration. AGP clvii 571. Momose 1915 Alv. CO, and PH of blood. BJ ix 485. 222 LITERATURE LIST Montgomery 1878 St. Thos. Hos. Repts. London, n. s. ix. 1881 Muscle contraction and ameboid motion, AGP xxv 497. Mond, Ramsay & Shields 1898 Absorption of H, by metals. PRS Ixii 290. Moore, A. 1910a Temp. coef. of cytolysis and hemolysis = 200 for 10°. QJEP iii 257. 1910b Temp. coef. of regeneration. AE xxix 145. Moore, B. 1914 Iron and photosynthesis, PRS (B) Ixxxvii 556. —— & Roaf 1906 Lipoids and proteins precipitated by anesthetics in low concentration. PRS (B) Ixxvii 86. 1907 Osmotic pressure of colloids. BJ ii 34. 1908 More salts dialyze from serum than from erythrocytes. BJ iii 55. —— & Webster 1913 Photosynthesis of formaldehyde from CO, and H.O. PRS (B) Ixxxvii 163. — & Whitley 1909 Oxidases. BJ iv 136. Morawitz, H. 1910 Adsorption of HgCl, by erythrocytes. KZ vi 250. 1910 Adsorption of antiseptics by bacteria. Reduction of heavy metals by adsorption. KCB i 301. Morawitz, P. 1909 Oxidation in blood. AEP Ix 208. Morgulis & Fuller CO, in sea cannot be titrated with phenolphthalein. JBC xxiv 31. Morgan, J. 1915 Measurement of surface tension. ZPkC. Morgan, T. & Stockard 1907 Effects of salts and sugar on frog’s egg. BB xiii 272. Morse, H. 1914 Osmotic pressure of sugar solutions. CIWP (No. 108). —— & Horn 1001 Osmotic membranes. ACJ xxvi 80. Morse, M. 1912a Eggs in sperm extracts. JEZ xiii 471. 1912b Parthenogenesis. JEZ xiv 471. 1915 Halogens and enzymes. JBC xxii 125. 1916 Autolysis is autocatalyzed by H’. JBC xxiv 163. Moruzzi 1910 Urea liberates NH; BZ xxviii 97. Mourson & Schlagdenhauffen 1882 Sea urchin blood. CRA xcv 791. Mouton 1897 Turgor regulation. CRA cxxv 407. Miiller, C. 1912 Absorption of gases by non-electrolyte solutions. ZPkC Ixxxi 483. Miller-Thurgau 1880 Capillarity and undercooling. LJ ix 176. 1886 Undercooling of plants. LJ xv 4o0. Murlin, Edelmann & Kramer 1913 CO, and O, of blood in stasis. JBC XVI 79. —— & Kramer 10913 Respiration in glycosuria. JBC xv 365. Myers & Acree 1913 H, electrode. ACJ 1 306. Nageli 1855 “Pflanzenphysiologische Untersuchungen.” 1885 “Pflanzenphysiologische Studien.” Zurich. Nagel 1909 “Handbuch der Physiologie des Menschen.” Braunschweig. F. Vieweg. Nasse 1869 Swelling of muscle. AGP ii 97. Nathansohn 1904 Lecithin changes permeability when wet. JWB xxxix 607. Nemec 1900 Geotropism of plants. BDBG xviii 241. Neilson 1906 ae black poisoned by HCN in splitting of amygdalin. P xv 148. Nernst 1888 Formula for electrode and diffusion potential. ZPkC ii 613, 630. 1889 Formula for diffusion potential. ZPkC iv 129. 1890 Permeability and solution in plasma membrane. ZPkC vi 37. 1892 Solution tension and polarization. ZPkC ix 137. 1897 Tesla currents do not stimulate. APk Ix 600. 1911 “Theoretical Chemistry.” Trans. of 6th Ed. Macmillan. — & Barratt 1904 Verification of Nernst’s theory of stimulation. ZEC 663. LITERATURE LIST 223 —— & Riesenfeld 1902 Diphasic concentration cells. APk (4) viii 600. Neuberg 1911 “Die Harn sowie die uebrigen K6rperflussigkeiten.” Berlin. Neufeld & Haendel-1908 Hemolysins are cytolytic. Bile salts dissolve blood shadows. AKG xxviii 572. ie Nicloux 1913-14 Absorption of CO, by blood. CRA clvii 1425, clviii 363. Nishi uO Paeee is secreted by glomeruli and resorbed by tubules. AEP xii 329. Noguchi 1902 Combination of lecithin and saponine. UPMB (Nov.). 1905 Snake venom protects erythrocytes. JEM vii 101. Nolf 1904 A of venous and arterial blood. AB xx 1. Norton & Hsu 1916 Disinfection. JID xviii 180. Nothmann-Zucherkandl 1912 Protoplasmic streaming quickly stopped with anesthetics but continues weeks without O,. BZ xlv 412. 1915 Toxicity of anesthetics increased by salts. JZPB ii 10. Novak, Leimdoerfer & Porges 1902 Alveolar CO, during pregnancy. ZKM Ixxv 301. Noyes 1907 Electric conductivity. CIWP (No. 63). —— & Blanchard 1900 Color of Co ions and molecules. JACS xxii 726. —, Melcher, Cooper & Eastman 1910 Conductivity at high temperatures. ZPkC Ixx 335. Okada 1915 Liver bile PH = 7.75, gall more acid. JP 1 114. Oker-Blom 1900 Conductivity of sand + 40% solution = 25% of con- ductivity of solution. AGP Ixxix 510. 1901 Bioelectric currents. AGP Ixxxiv IoI. Onaka 1911 Oxidation of blood platelets. ZPC Ixxi 193. Oppenheimer 1909 Handbuch der Biochemie des Menschen und der Tiere. 1913 “Die Fermente.” Leipzig. Osborne 1906 Intracellular colloid salts. JP xxxiv 127. Osterhout 1910 Permeability of cells to Ca. ZPkC Ixx 408. Ig1t Permeability of cells. S xxxiv 187. 1912a Permeability. S xxxv 112. Ig12b Plants requiring Na. BG liv 532. 1g12c Change in permeability. S xxxvi 350. 1913a Pseudo plasmolysis. BG lv 446. 1913b Anesthetics and permeability. S xxxvii I1t. 1g14a Alkali and permeability. JBC xix 335. 1g14b Acid and permeability. JBC xix 493. tg15a Acids vs. salts. JBC xix 517. 1915b Polyvalent ions and permeability. BG lix 464. 1g15sc Permeability. AJB it 93. 1g1sd Decrease in perm. BG lix 317. tg15e Abnormal permeability without death. BG lix 242. Ostwald, Wm. 1889 Dilution law. ZPkC iii 170. 1890 Elec. properties of semipermeable membranes. Becquerel phe- nomenon. ZPkC vi 71, 74. 1892 Color of ions. ZPkC ix 579. 1897 Metastable state. ZPkC xxii 302. 1899 “Grundriss d. allg. Chemie.” 3rd Ed. Leipsic. 1900 Small crystals more soluble than large. ZPkC xxxiv 495. —— & Luther 1910 “Handbuch Physiko-Chemischer Messungen.” 3rd Ed. Leipsic. Ostwald, We 3995 Gammarus pulex will live in fresh or sea water. AGP cvi 568. 1907a Disperse systems. KZ i 201. 1907b Adsorption and toxicity. AGP cxx 19. 1907c Oxidases sensitive to light. ZB x 130. 1908 Dissociation of oxyhemaglobin. KZ ii 264. 1g09 Grundriss der Kolloidchemie. Dresden, Steinkopff. 224 LITERATURE LIST 1912 Color of indicators. Dispersion of dyes. KZ x 07. 1913 Viscosity of sols. TFS ix 34. Otto 1913 Narcosis and evolution. ZB lix 165. Overton 1895 Plasmolysis and permeability. VNGZ xl 1. 1897 Cells permeable to free alkaloids but not their salts. Permea- bility to NH;. ZPV xxii 189. 1899 Permeability of cells. VNGZ xliv 88. 1900 Permeability and partition coefficient. JWB xxxiv 6609. 1901 “Studien ueber die Narkose.” Jena. 1902a Permeability of muscle 0.65% NaCl for frog. AGP xcii 115. 1902b Na (or Li) necessary for muscle contraction. AGP xcii 346. 1904a Frog’s kidneys regulate osmotic pressure. VPMG (NF) xxxvi 277, 1904b Ions restoring excitability of sugar muscle. AGP cv 176. 1907 Frog’s egg membrane permeable to crystalloids. II p. 878 Nagel’s Handb. d. Physiol. d. Menschen. Packard 1905 Injection of alkali decreases symptoms of O, want. AJP XV 30. Paine 1912a Permeability of yeast. PRS (B) Ixxxiv 289. 1912b Decrease in dispersion of sols and rate of precipitation by electrolysis. KCB iv 24. Palitzsch 1911a PH by methyl red. BZ xxxvii 131. 191th PH of sea water. BZ xxxvii 116. 1915 Boric-borax mixtures for PH. BZ 1xx 333. Pantanelli 1904 Osmotic pressure of mould on concentrated KNO,. Col- loid swelling and turgor. JWB xl 303. 1906 Acetates increase permeability of fungi to enzymes. AB v 355. Pascheles 1898 Coagulation in emulsoid gels. AGP 1xxi 333. Pascucci 1905 Erythrocyte stroma 4% lipoid and % proteins. Artificial lipoid membranes. BCPP vi 543. 1907 Perm. of lipoid mem, to pro-enzymes, BZ vi 358. Pasteur 1858 Asymmetric fermentation of tartaric acid. CRA xlvi 615. Paul 1901 Ionization hastens toxic action of heavy metals. ZPkC xxxvii 754. —, Birstein & Reuss 1910 Adsorption of antiseptics by bacteria. BZ XxXix 202, — & Kronig 1896 Disinfection with Hg ions. ZPkC xxi 414. Pauli 1903 Lyotrope series for alkali albumin reversed for acid albumins. Ba, Sr and Ca precipitate proteins irreversibility. BCPP v 27. 1905 Precipitation of emulsoids with heavy metals. BCPP vi 233. 1906 Electric charge of protein. BCPP vii 531. 19007 Heat coagulation of acid albumin. BCPP x 53. 1910 Colloidal state and physiology. AGP cxxxvi 483. 1912 “Kolloidchemie der Muskelkontraktion.” Dresden. Steinkopff. —— & Falek 1912 Caffeine and hydration of proteins. BZ xlvii 260. —— & Flecher 1912 Precipitation of emulsoids with suspensoids. BZ xli 461. — & Handovsky 1908 Ion-protein compounds. BCPP xl 4r5s. 1909 Acid albumin. BZ xviii 340. 1910 Alkali-albumin. BZ xxiv 239. —— & Matula 1916 Thermo-current of muscle. AGP clxiii 355. —— & Rona 1902 Swelling of gels. Glycerine and sugar favor and urea inhibits gelation. BCPP ii 1. —— & Samec 1909 Proteins increase solubility of Cas(PO,), and CaCO, but not of alkali salts appreciably. BZ xvii 235. 1913 Viscosity and optical rotation of emulsoids. KZ xii 222, ——, Samec & Grauss 1914 Optical rotation of protein salts. BZ lix 470. — & Wagner to10 Acids and alkalis increase viscosity of proteins. BZ xxvii 296. LITERATURE LIST 225 Pavloff po Work of the Digestive Glands.” Trans. of 2nd Ed. ondon. P Peabody 1914 No relation of PH to dyspnoea in cardio-renal. AIM xiv 236. 1916 Alv. CO, = 6 mm in diabetic coma. AJMS cli 184. Pearl & Gowan 1914 Refractive index of serum. PSEB xii 48. . Pekelharing 1914 Nucleo-protein, Ca and blood coagulation. ZPC Ixxxix 22 —— & Ringer 1911 Cataphoresis of pepsin. ZPC Ixxv 282. Pelet-Jolivet & Anderson 1908 Adsorption and electric charge. KZ ii 225. Perrin 1904-5 Dielectric constant and contact electricity. Formula for cataphoresis. JCP ii 601, iii 50. 1908 Stokes law and Brownian movement. CRA cxlvi 960, cxlvii 475. 1909 Ultramicroscopy of coagulation. ACP (8) xviii 89. 1911 Avogadro’s No. = 6X10” molecules in mol. wt. CRA clii 1165, 1382. 4 Pfaundler 1905 PH of blood of premature babies = 6.55. Normal = 7.5. K xli 161, 174. ; Pffeffer 1873 “Physiologische Untersuchungen.” Leipsic. 1877 “Osmotische Untersuchungen.” Leipsic, Engelmann. — & Hansteen 1893 Splitting of starch in germinating corn inhibited by sugar. BVGW xlv qe2t. Pfeiffer & Von Modelski 1912-3 Amino acids bind NaCl. ZPC 1Ixxxi 320, Ixxv I. Philip 1914 “Physical Chemistry and Its Bearing on Biology.” 2nd Ed. London. Philips 1907 Effect of solutes on solubility of gases. TFS iii 140. Phillipson, Hannevart & Thieren 1910 A of fresh water animals. AJP ix 460. Philoche 1908 Maltase action is autocatalytic. JCP vi 213, 355. Pickering 1910 Haptogen membranes and emulsions. KZ vii 11. Pictet 1893 Diatoms live at —200°. ASPN xxx 311. Picton & Linder 1892 Colloids show Tyndall phenomenon. JCS 1xi 148. Pierce 1910 Coagulation of substrate and enzyme action. JACS xxxii 1517. Piper 1912 “Elektrophysiologie Menschlicher Muskeln.” Berlin. Planck 1890 Formula for diffusion potential. APC xl 56r. Plesch 1909 Hemodynamics. ZEP vi. Pohl 1891 Chloroform is concentrated by erythrocytes, lecithin, cholesterin and oil, AEP xxviii 210. Polanyi 1911 Blood is acid in starvation. BZ xxxiv 1092. Porges 1905 Agglutinin or heat transforms bacteria into suspnesoids. ZB xl 133. tg11 Acidosis. WKW. 1913 CO, tension and respiration. BZ liv 182. —— & Neubauer 1907 Lecithin precipitated by Ba, Sr, Ca’ and Mg like suspensoid. BZ vii 152. ; Port 1910 Effect of ions on hemolysis by saponin. Resistance greater the less P (lecithin?) erythrocytes contain. DAKM xcix 259. Porter 1911 Is rennin pepsin? JP xlii 380. 1914 Adsorption of trypsin by serum alb. BJ viii 50. Portier 1910 A of marine vertebrates. JPP xii 202. Posnjak 1912 Swelling pressure of gelatine. KCB iti 417. Poulton 01s re ed below 2.5% anticipates coma. PRS (M) vii 171; jP p. i). Pototsky 1902 Diuresis and NaCl starvation. AGP xci 584. Prenant 1910 Mitosis. JAP xlvi 511. Pribram 1011 Lipoids precipitated by anesthetics. AGP cxxxvii 350. Price 1914 Ultramicroscopy of plant cells. AB xxviii 601. Prideaux 1911 PH of phosphate mixtures. BJ vi 122. 226 LITERATURE LIST Pringsheim 1912 “Die Reizbewegungen der Pflanzer.” Prowazek 1903 Phagocytosis of echinoderm egg. ZAP ii 385. 1907 Formation of plasma membrane. BC xxvii 734. Pugliese 1906 Effect of salts on smooth muscle. AIB xlvi 371. Putter 1904 Toxicity of great O, pressure. ZAP iii 363. 1911 Vergleichende Physiologie. Jena, Fischer. Pulst 1902 Cu non toxic to penicillium. JWB xxxvii 205. Quagliariello 1910 Saline cathartics. BZ xxvii 517. 1912a Change of PH during heat coagulation of proteins. BZ xliv 157. 1912b PH normal in fever. BZ xliv 162. Quincke 1888a Plasma membrane fat. APk xxxv 580; SKPA xxxiv 791. 1888b Adsorption of colloids. APk xxxv 582. 1902 Surface tension of sols. APk ix 969. Quinton 1900 A of marine animals. CRA cxxxi 952. 1904 Change of A of fish. CRB lvii 470. Raben ues and Si in sea water. Wissensch, Meeresunts. Kiel, viii 1-286. Radziszewski 1883 Compounds that emit light on oxidation at low tem- perature. BDCG x 597. Raehlmann 1906 Ultramicroscopy of protein. AGP cxii 128. Ramsay 1894 Diffusion pressure of gases. PM xxxviii 206; ZPkC xv 518. Ramsden 1904 Haptogen membranes. PRS Ixxii 156; ZPkC xlvii 343. Ransom 1901 Cholesterin protects erythrocytes from saponin, DMW 194. Raoult 1901 Formula for osmotic pressure. AUG xiii 173. Raulin 1870 Salt solution for plants. CRA Ixx 634. Rayleigh 1879 Surface tension measurements. PRS xxix 71. 1899 Tyndall phenomenon and color of sky. PM xlvii 375. Rayleigh, G. B. 1915 Oxidasis and respiration. JBC xxii 99. Reid 1900 Ligature of lymphatics does not decrease absorption by gut. PT (B) cxcii 231. 1901 Negative osmose of diaphragm of live gut wall. JP xxvi 436. 1904 Osmotic pressure of purified protein = 0. JP xxxi 438. Rehfuss 1915 Achylia gastrica. AJMS cl 72. — , Bergein & Hawk 10914 Residuum in empty stomach. JAMA Ixiii 11. —— & Hawk 1914 Constant acidity of gastric juice. JAMA Ixiii 2088. Reicher 1908 Anesthesia leads to pathological acid production. ZKM v 235. Reinders 1913 Abnormal partition coefficient and hydrolysis. KZ xiii 96. Rhumbler 1898 Contractile vacuole. AE vii 103. 1905 Ameboid motion. ZWZ 1xxxiii 1. 1910 Phagocytosis. AE xxx 1094. ; Ribbert 1913 Path of excretion of hemoglobin by kidney. ZP xxiv 244. Richards, A. 1914a X-rays and cell division. BB xxvii. 1914b X-radiation of enzymes. AJP xxxv 224. 1g1sa X-radiation. AJP xxxvi 400. 1915b Physiology of radioactivity. S xlii 287. Richards, T. 1897 n/1o calomel electrode. ZPkC xxiv 30. 1906 Nephelometer. ACJ xxxv 510. 1915 Atomic compressibility. JACS xxxvii 1643. —— & Wells 1904 Nephelometer. ACJ. Richardson, Nicol & Parnell 1904 Diffusion of H, (as H) through Pt. PM (6) viii 1. ; Riddle & Spohn 1912 Change in composition and permeability. S xxxv 462. Rigg 1916 Salts in kelp. S xliii 602. Ringer, S. 1880-3 Effect of salts on heart. JP iii 380, iv 20, 222. 1886 Effect of salts on muscle. JP vii 201. — & Phear 1805 Effect of salts on tadpoles. JP xvii 423. —— & Gainsbury 1890 Salts and coagulation of blood. JP xi 360. Ringer, W. 1910 Uric acid and phosphates. ZPC Ixvii 332. LITERATURE LIST 227 1916 Pepsin anodic even in acid. H’ acts on substrate. VKAW xviii 738. —— & Van Trigt 1912 PH and ptyalin. ZPC Ixxxii 484. Roaf 1910 Osmotic pressure of proteins reduced by salts. QJEP iii 75, 171. 1912a Hemolysis. QJEP v 131. 1912b Marine organisms. JP xliii 449. 1913 O, tension of tissues. PRS (B) Ixxxvi 215. 1914 Muscle contraction. PRS (b) Ixxxviii 139. Robertson 1906 Strychnine antitoxic to Na,SO,. JBC i 507. 1907 Dissociation of proteins. JPC xi 437, 542. 1910 Dissociation of acid and alkali albumins. JPC xiv 377, 528. 1911 Cell division, AE xxxii 308. 1912 Oocytin from serum and sperm. JBC xii. Rodier 1899 A of marine vertebrates. TLA 103. Rohde 1906 Haptogen membranes. AP (4) xix 135. Rohonyi 1912 Protein binds H’ and Cl’, BZ xliv 16s. Rolly 1912 PH in disease. MMW. 1913 PH in disease. ZN xlvii 617. Rona 1go1 Cl’ in blood. BZ xxix sor. —— & Doeblin 1910 Permeability of erythrocytes to sugar. BZ xxxi 215. —- & Gyoergy 1913 Diffusible Na and CO, in blood. BZ xlviii 278. 1913 When PH is less than 4.8 serum protein binds Cl’. CO, in- creases diffusible alkali in serum. Na‘, K’, Cl’ and free CO, in blood. BZ lvi 416. — & Michaelis 1909a Charcoal adsorbs sugar. BZ xvi 480. 1909b Permeability of erythrocytes. BZ xvi 60, xviii 375. 1g09c Ca" in milk. BZ xxi 114. —— & Wilenko 1914 PH and use of sugar by heart. BZ lix 173. — & Takahashi 1910 Permeability of erythrocytes to sugar. BZ xxx 99. Ig1I Ca” in blood. BZ xxxi 336. 1913 All Na’ and K’ in serum are diffusible. %4 Ca is bound. BZ xlix 370. — & Tosh 1914 Urethane displaces adsorbed dextrose from animal charcoal. BZ Ixiv 288. Rontgen & Schneider 1886 Adsorption of ions. Negative adsorption. P xxix 165. Rosa 1913 Weston cell = 1.01827 at 20°. BBS ix 493. Rosenthaler 1910 Synthesis of amygdalin with emulsin. BZ xxviii 408. Ross 1911 “Induced Cell Division and Cancer.” Blakistons. Rossi 1909 “La Reatione delle urine nelle forme febrille.” Naples. Rost 1911 Nucleus permeable to dyes. AGP cxxxvii 350. Rowntree, Marriott & Levy 1915 PH of dialysate with indicator. JHHB xxvi 114. Rubner 1913 Fermentation by yeast same in 2.5% and in 20% sugar. Synthesis of glycogen. AAP (Sup.) 240. Rudolphi 1895 Dilution law for strong electrolytes. ZPkC xvii 385. Ruhland 1908 Diffusion through artificial lipoid membranes and permea- bility to acids. JWB xlvi 1. 1912 Ultrafiltration and vital staining. BDBG xxx 139. 1913 Colloids and cells. KZ xii 113. Ryffel 1909 Lactic acid and acidosis. JP xxxix (p. xxix). Rywosch 1907 Erythrocytes of ox and sheep containing most cholesterin are most resistant to saponine and least to hypotonicity. AGP cxvi 220. Salamonson 1916 Psychogalvanic reflex. VKAW x 997. Salge 1911 A of newborn, KZ i 126, ii 347. 1912 PH of newborn. KZ iv 171. Salm 1906-8 Indicators. ZPkC Ivii 471, Ixvii 83. 228 LITERATURE LIST Salzmann 1913 Individual factors in narcosis, AEP 1xx 233. a Samec be Swelling of starch: Li, Mg, Ca, Na, K, ae Ba. KCB iii 1, Savcheuker & Aristovsky 1912 PH and phagocytosis. ASB xvii 128, Scatchard & Bagert 1916 Dinitrobenzoylene-urea PH 6-8. S xliii 722. Schade ane al and bladder stones due to lack of protection colloids. 1 375. 1910 Lyotrope series and association of H,O color of sols. KZ vii 26. 1913 Tendons swell in acid and shrink in alkali, ZEP xiv 1. — & Boden 1013 Colloidal solutions of uric acid. ZPC Ixxxiii 347; Ixxxvi 238. Schafer 1902 Swelling of frog’s embryos. AE xiv 306. Schaffnit 1911 Freezing out of colloids ZAP xii 223. Schaffer 1888 Rate of diffusion. ZC ii 300. Scheurlen 1896 NaCl increases toxicity of phenol. AEP xxxvii 84. —— & Spiro 1897 NaCl increases toxicity of phenol. MMW 81. Schimkewitsch 1902 Amitosis. BC xxii 605. Schlaepper 1906 Oxidation in cells. AGP cxiv 301. Schloss 1912 Water retention favored by Na and inhibited by Ca. ZK iit 441. Schmidt, C. 1909 Conversion table: millivolts and H’. UCPP iii ror. Schmidt, G. 1910 Adsorption saturation. ZPkC Ixxiv 689, Ixxvii 641. Schmidt-Neilsen 1909 Change of A of fish. NVS 20. ; 1909-10 Adsorption of colloids irreversible. ZPC Ixviii 317; 1x 426. Schneider 1913 Alveolar CO, tension after descent. AJP xxxii 295. Schénbien 1863 Catalysis. JPC Ixxxix 323. Schorr 1912 Protein most easily precipitated by albumin at isoelectric point. BZ xxxviii 424. Schryver 1910 Photosynthesis of formaldehyde. PRS (B) 1xxxii 226. Schucking 1903 Fertilization membrane preformed. AGP xcvii 85. Schiitt 1904 Haptogen membranes. APm (4) xiii 712. Schiitz 1885 Peptic digestion proportional to square root of pepsin con- centration. ZPC ix 577. Schulemann 1912 Dispersion and vital staining of Goldmann pyrrol cells. APm cel 252, Schulz 1912 A of newborn. ZK iii 251, 405. Schulze 1884 Schulze’s rule (valence). JPkC xxvii 320. Schwarz 1907 Ions restoring excitability of sugar muscle. AGP cxvii 161. 1911 Tetanus increases osmotic pressure of muscle.- BZ xxxvii 34. —— & Lemberger 1911 Effect of H’ on blood vessels. AGP cxli 149. Schwartz 1913 Skin current of frog. ZP xxvi 734. 1915 Frog’s skin current. AGP clxii 162, 547. Schiicking 1902 Marine invertebrates semipermeable. AAP 533. Schwyzer 1914 PH and blood corpuscles. BZ 1x 2097, 306. Scott, F. 1908 Regulation of respiration. JP xxxvii 301. 1915 Permeability of erythrocytes to protein. JP 1 128. 1916 Permeability of blood vessels. JP 1 157. Scott, G. 1913a Osmotic equilibrium of fish. BB xxv 121, 1913 Osmotic equilibrium of fish, ANYA xxiii 1. Scott, R. 1916 PH and dissociation of oxyhemoglobin. JLCM i 608. Scudder 1914 “Conductivity and Ionization Constant of Organic Com- pounds.” N. Y. Sellards 1914 Acidosis in Tepes, JHHB xxv 141. Senter 1903-10 Enzymes. ZPkC xliv 257, li 673, 681, 701, lii 5rr. Shaklee & Meltzer 1909 Shaking enzymes. AJP xxv 81. Shattuck & Dudgeon 1912 Effect of drying bacteria. PRS (B) Ixxxv 127. Sheppard 1914 “Photochemistry.” Longmans. Shields 1893 Hydrolysis of KCN. ZPkC xii 167. LITERATURE LIST 229 Shorter 1909 Haptogen membranes. PM (6) xvii 560. cai —— & Ellingworth 1916 Soap and not OH’ emulsifies. PRS (A) xcii 231. Shull 1913 Permeability of hulls of Xanthium seeds like plasma mem- : brane. BG lvi 169. Siebeck 1912 Permeability of kidney cells. AGP cxlviii 443. _ 1913 Permeability of muscle to KCl. AGP cl 316. Siedentopf & Zsigmondy 1903 Ultramicroscope. APk x 1. Simon 1910 Protein-salt compounds. ZPC Ixvi 70. Slator 1903 Catalyser may alter type of reaction. ZPkC xlv 513. Snyder 1908 Temp. coef. of vital processes. AJP xxii 309. Sollman 1903 Selective action of kidney. AJP ix 425, 454. 1904 Fundulus egg permeable to water (?). AJP xii 112. —— & Pitcher 1911 Asphyxia stimulates vasomotor center. AJP xxix 100. Sorensen, S. P. L. 1909 H’ and enzymes. BZ xxi 130, xxii 352. 1912 PH methods. EP xii 393. — & Palitsch 1910 Alphanaptholphthalein. BZ xxiv 381. 1913 PH of sea water. BZ li 307. Souza 1911 Reduction of thermolability of trypsin. JP xliii 374. Spaeth 1913 Effect of salts on chromotaphores. JEZ xv 527. Spiro 1904 Acids and alkalis increase swelling of gelatine. BCPP v 276. —— & Bruns 1808 NaCl increases toxicity of phenol. AEPP xli 355. —— & Henderson, L. 1908 Model of blood alkalescence. Na.Alb = H.Alb+NaHCO;. BZ xv 114. Spring 1896 Deltas formed by precipitation of mud by salts of sea water. Stadler & Kleemann 1911 Adsorption of NH by erythrocytes. BZ xxxvi 301, 321. Starling 1899 Diffusion from tissues into blood. Osmotic pressure of proteins. JP xxiv 317. 1915 “Principles of Human Physiology.” Phila. Stempell 1914 Contractile vacuole. ZJ xxxiv 437. Stern 1912 Osmotic pressure of concentrated solution. ZPC Ixxxi 441. Stewart 1897 Electric conductivity of erythrocytes. ZP xi 332. 1899 Increase in conductivity of erythrocytes. Method of deter- mining their volume. JP xxiv 211, 356. 1901 In hemolysis salts come out before hemoglobin. JP xxvi 470. 1909 Hemolysis. JPET i 49. Stieglitz 1908 Catalysis. ACJ xxxix 62. Stoklasa 1908 Ash of azobacter = K,HPO, ZBk xxi. 1916 Significance of K in plants. BZ Ixxiii 107. Strachan & Chu 1914 Transference no. of I. JACS xxxvi 810. Straub 1904 Adsorption of veratrin by heart of aplysia. AF i 65. Straub 1912 Salts produce current of injury of heart. ZB Iviii. 1913 Effect of alkaloids on muscle and heart. ZP xxvi 990. Stiibel 1911 Fluorescence of tissues in ultraviolet light. AGP cxlii 1. 1914 Ultramicroscopy of blood coagulation. AGP clvi 361. Sumner 1905 Osmose and fish. BBF xxv 53. 1907 Osmose and fish. AJP xix 61. Ig11 Objective study of sight in fishes. JEZ x 400. Svedberg 1909 Colloidal sulphur. ZPkC Ixvii 240. 1909 No boundary between solutions and sols. ZPkC Ixvii 105-251. 1910 Brownian movement. KZ i. Swellengrebel 1905 Plasmolysis of bacteria. ZB xiv 374. Szili 1906 PH of fetal blood. Dogs killed by infusion of HCl at PH = 6.05. AGP cxv 72, 82, & Friedenthal 1903 Buffers for Ringer’s fluid. AAP 550. Sziics 1910 Permeability. SWA cxix 737. 1911 Effect of electric current on permeability. JWB lii 326. 230 LITERATURE LIST 1912 Al’”’ increases permeability of spirogyra. JWB lii 8s. 1913 Al’ increases viscosity of spirogyra H,O, kills. JWB lii 260. Szyszkowski 1908 Adsorption on foam. ZPkC Ixiv 387. Tamman 1888 Isosmotic solutions. APk xxxiv. 1892 Permeability of Traube’s membranes. ZPkC x 255. Tanaka 1911 Acids on castor bean lipase. JCET v 25. 1912 PH and lipase. JCET v 125. Tangl 1906 PH of stomach. AGP cxv 64. —— & Farkas 1904 Respiration of fish eggs. AGP civ 624. Tashiro 1913 CO, production by nerve. AJP xxxii 107, 137. —— & Adams 1914 Anesthesia and CO, by nerve. JZP-CB i 450. Taylor 1906 Synthesis of fat by lipase. JBC ii 87. 1907 Synthesis of protein by trypsin. JBC iii 87. 1915 “The Chemistry of Colloids.” Longmans. Teague & Buxton 1906 Charge of yeast reversed by ions. ZPkC Ivii 76. 1907 Immune bodies cathodic. JEM ix 254. 1907 Dispersion of colloids. ZPkC 1x 470. Temple 1915 Salting out of alcohol. Thesis. U. of Minn. Tennent 1910 PH and Mendelian dominance. CIWP (No. 132) 117. Thiel & Strohecker 1914 Hydration of CO, and dissociation of H.CO,. BDCG xlvii 945. Thiselton-Dyer 1899 Seeds live at —250°. PRS Ixv 361. Thomas 1915 Anesthetics increase viscosity of lecithin suspensions. JBC xxiii 359. Thornton 1910 Naturally cathodic plant cells. PRS (B) Ixxxii 638. Thunberg 1911 Autoxydation of lipoids. SAP xxiv go. Tigerstedt 1910 Handbuch der Physiologischen Methodik. Leipsic. Titoff 1910 Adsorption and solid solution. ZPkC Ixxiv 641. Toda & Taguchi 1913 A of frog’s urine. ZPC Ixxxvii 371. Torrey 1912 O, and polarity. U. Cal. Pub. (Z) ix 2409. Tower 1896 KCI lessens diffusion potential. ZPkC. Traube, I. Effect of ions on density of solution. ZAC iii 11. 1904 Stalagmometer. Surface tension of stomach less than blood. AGP cv 541, 550. 1908a Anesthetics inhibit hemolysis. Hemoglobin is hemolytic. BZ X 371. 1908b Surf. Ten. norm. urine greater than blood. Less in nephritis. AGP cxxiii 419. 1g08c Surface tension and hemolysis. BZ xvi 371. 1909 Parthenogenesis. BZ xvi 182. 1910 Haftdruck theory. BZ xxiv 323. 1g11 Haftdruck theory. AGP cxl 109. 1912 Viscostagometer. BZ xlii 500. 1913a Adsorption and solution. AGP cliii 273. 1913b Catalysis. AGP cliii 309. I913c Many lipoid-insoluble dyes penetrate cells. BZ liv 305. 1915 Narcosis. AGP clx 5o1. —— & Kohler 1915 Solutions and swelling opposed to gelation and shrink- ing. JZPS ii 427. —— & Marusowa 1915 Swelling of seeds. JZPB ii 370. Traube, M. 1867 Precipitation membranes. AAP 87, 609. Trauty 1905 Chemiluminescencz. ZPkC liii 1. Trendelenburg 1912 Effect of salts on smooth muscle. AEP Ixix 79. Trillat 1904 Oxidase action of Mn + colloid. CRA cxxxviii 274, Trondle 1910 Light increases the permeability of plant cells. JWB xlviii 171. . . True 1914 Toxicity of Aq. dist. AJB i 255. 1915 Conversion table for sea water. S xlii 732. LITERATURE LIST 231 Tschagowetz 1907 Bioelectric currents. ZB | 247. Turner 1915 “Molecular Association.” Longmans. Z Tyndall 1869 Tyndall phenomenon. PM (4) xxxvii_384. Tyrode 1910 Saline purgatives. Perfusion fluid. AIPd xx 20S. Underhill 1916 Acidosis causes sugar retention. PSEB xiii 111. Urano 1908a Accommodation of nerves to anisotonic solutions. ZB XXXii 450. 1908b A of frog’s muscle press juice = 62°. ZB (NF) xxxii 212. 1908c Permeability of muscle. ZB (NF) xxxiii 483. Usher & Priestly 1906-11 Photosynthesis. PRS (B) Ixxvii 369; Ixxx 318; Ixxxiv I0I. Usui 1912 Part. coef. erythrocytes same after extracting lipoids. ZPC Ixxxi 173. Van Bemmeln 1899 Spontaneous alteration of vapor pressure of gels. ZAC xx. 1900 K’ of K,SO, adsorbed leaving H,SO, in solution. ZAP xxiii III, 321. Van Calcar & Loby de Bruyn 1904 Precipitation of dissolved crystalloids by centrifugal force. RTCP xxiii 218. Van der Laan 1915 A of blood same as milk. BZ Ixxi 280. Van Slyke & Cullen 1914 Formula for urease action. JBC xix 141. —,, Cullen é Stillman 1915 CO, in blood increased after meals. PZEB xii 184. —— & Zacharias 1914 PH = 87 for urease-urea combination. PH = 7 for urease decomposition. JBC xix 181. Van Rysselberghe 1899 Turgor regulation. Plant cells permeable to KNO,;. MARB Iviii 1. 1901 Temperature coefficient of rate of plasmolysis. BARB 173. Van’t Hoff 1887 Formula for osmotic pressure. ZPkC i 488. Vernon 1904 Antitrypsin. JP xxxi 346. 1911 Indophenol oxidase. JP xlii 402. 1912a Anesthetics below a certain high concentration do not affect indophenol oxidase. JP xlv 197. 1912b Toxicity of anesthetics to oxidase. BZ xlvii 375. 1913 Autocatalysis of trypsinogen. JP xlvii 325. 1914 Oxidation and lipoids. BZ 1x 202. Verworn 1909 Theory of narcosis. DMW (No. 37). 1913 Irritability. New Haven. Yale Univ. Press. Verzar I912a Perfused muscle continues high rate of respiration minutes after tetanus. JP xliv 243. t912b Thermo-current of nerve. AGP cxliii 252. 1g12c Lack of oxygen and tissue respiration. JP xlv 39. Voigt 1914 Kupfer cells of liver take up colloidal silver. DMW (No. 10). Von Briicke 1908 Non contracting muscle may produce action current. AGP cxxiv 215. Von Dungern & Coca 1907 Hemolysis. MM'W (No. 47). 1908a Hemolysis. BKW 7. 1908b Hemolysis. MMW xlv 105. 1908c Hemolysis. BZ xii 407. Von Elissafoff 1912 Effect of ions on electroendosmose. ZPkC Ixxix 385. —— & Freundlich 1912 Electric polarization of glass, ZPkC Ixix 385. Von Erlanger 1897 Surface movements of nematode eggs. BC xvii 152, 339. Von Firth & Lenk 1911 Muscle rigor. BZ xxxiii 341. Von Halban 1909 Temperature coefficient of chemical reactions. ZPkC ; Ixvii 1609. : Von Jaksch 1890 Effect of diet on gast. acidity in children. ZKM xxiv 565. 232 LITERATURE LIST Von Schroeder 1903 Viscosity of gelatine increased by acids and alkalis. ZPkKC xlv 88 ; Von Veimarn 1910 Colloid state of crystalloids. Submicrons in gelatine. KZ vi 277, vii. ~ Von Wyss 1908 Reduction of Cl in blood by feeding NaBr and its effect on nervous system. AEP lix 186. Von Zeynek & Von Bernd 1910 Stimulation impossible with 100,000 altera- tions per sec. AGP cxxxvii I. Wachendorff 1911 Respiration of infusion. ZAP xili Io. Wachter 1905 Permeability to sugar. JWB xli 165. Waentig & Steche PH for catalase. ZPC Ixxii 226, Ixxvi 177. 1912 Action of catalase on H.O, is adsorption ao ZPC Ixxix 446. Wagner 1890 Lyotrope series and viscosity. ZPkC v 31. Wagner, H. 1914 Action of light on chlorophyll. PRE (B) Ixxxvii 386. Walbum 10913 Protein bleaches many indicators. BZ xlviii 291; 1 346. Walden 1892 Permeability of Traube’s membranes. ZPkC x 600. Walker, J, ato “Introduction to Physical Chemistry.” 6th Ed. Mac- millan. — & Cormack 1900 Dissociation constants of weak acids. JCS Ixxvii 13. — & Marshall 1913 Hemoglobin positive. JACS xxxv 820. Waller 1900 Electric effect of light on leaves. JP xxv (p. xvii). 1904 Increased conductivity of plant on stimulation. JLS (Bot.) xxv 22. Wallace & Cushing 1898 Rate of diffusion and of absorption by gut. AJP i 4tt. Walpole 1914 H, electrode. BJ viii 131. 1914 Aggregation of sols. BJ vili 170. Walters 1912 Reaction products on trypsin. JBC xii 43. Warburg, E. 1899 Formula for alternating current. APk Ixvii 497. Warburg, O. 1908 Oxidation of egg increases on fertilization. ZPC lvii 1. 1909a Oxidation of erythrocytes. ZPC lix 112. 1909b Cleavage of egg may be prevented by OH’ which increases oxidation. ZPC Ix 443. 1909c CO, analysis. ZPC Ixi 261. 1gt0a Oxidation in egg not dependent on cleavage. ZPC Ixvi 305. t910b Oxidation and anesthetics. ZPC Ixix 452. tgita Cell respiration and structure. MMW Iviii 289. tgttb Oxidation of cells. ZPC |xx 413. Igtic Oxidation and anesthetics. ZPC 1Ixxi 479. to12a No respiration in ground erythrocytes. AGP cxlv 277. 1912b Fermentation and oxidation. MMW (No. 47). 1g12zc HCN and oxidation. ZPC Ixxvi 331. 1913 Respiration of liver granules. AGP cliv 599. 1914 Blood charcoal oxidizes oxalic acid. AGP clv 547. 1915 Egg respiration. AGP clx 324. —— & Meyerhof 19012 Cell respiration and structure. AGP cxlviii 295. 1914 Oxidation of lecithin by iron. ZPC Ixxxv 412. — & Wiesel 1912 Action of anesthetics on anaerobic processes and enzymes. AGP cxliv 465. Warner 1914 Formaldehyde from chlorophyll. PRS (B) 1xxvii 378. Washburn 1909 Lyotrope series and A. JACS xxxi 322. io15 “Principles of Physical Chemistry.” N. Y. McGraw-Hill. —— & Bell 1913 Apparatus for elec. conductivity. JACS xxxv 177. Wasteneys oie, Oxidation in egg reduced by stopping development. JBC xxiv 281. Webster 1902 Absorption of liquids by tissues. Decennial Pub. Univ. of Chicago x 105. Weinland 1894 Effect of salts on cilia. AGP Iviii tos. LITERATURE LIST 233 Weizsacker 1912 Heart beat in KCN. AGP cxlvii 135. : Wessely 1903 Absorption of subcutaneous injections. AEP xlix 412. Whatmough 1902 Surface tension measurement. ZPkC xxxix 120. White 1911 Viscosimeter. BZ xxxvii 481. - Whitney 1908 Dessication of rotifers. AN xlii 665. —— & Blake 1904 Polyvalent ions and cataphoresis. Removal of Cl from albumin. Peptisation. JACS xxvi 13309. : —— & Ober 1902 Ion equivalents for precipitating sols. ZPkC xxxix 630. Widmark 1910 A of fresh water animals. ZAP x 431. to11r Thunberg-Winterstein micro-respirometer. SAP xxiv 321. Wiedemann 1852 Cataphoresis and electroendosmose. APk 1xxxvii 321. —— & Luedeking 1885 Heat of swelling of colloids. APk xxv 145. Wijs 1893 Dissociation of water. ZPkC xii 514. Wilke & Meyerhof 1910 Polarization and colloid precipitation with alter- nating current. AGP cxxxvii. Williams, Riche & Lusk 1912 Dynamic action of protein. JBC xii 349. Wilsmore 1901 Lyotrope series and electrolytic solution tension. ZPkC XXXVi OI. Windaus 1908 Reaction between saponin and cholesterin. BDCG xlii 238. Windle 1895 Electric effects produced by blood circulating in magnetic field. JAP xxix 346. Winkleblech 1901 Ampholytes. ZPkC xxxvi 546. Winterstein 1897 Death rigor of muscle does not occur in O.. AGP cxx 225. 1910 Handbuch der vergleichende Physiologie. 1912 Microrespirometer. BZ xlvi 440. 1913 Anesthetics do not lessen solubility of O, in oil. BZ li 143. 1914 Narcosis with alcohol increases oxidation of spinal cord. BZ xi 81. Woelfel 1908 Distribution of salts in hemolysis. BJ iii 146. Wolff, F. 1908 Temp. coef. of Weston cell. BBS v 300. Wolff, J. 1908 Oxidase action of colloidal ferric-ferrocyanide. CRA exlvii 745. Wood 1903-6 Affinities of feeble bases. TCS Ixxxiii 568, Ixxxix 1839. 1908 Amphoteric metallic hydroxides. TCS xciii 411. Woodland to11 Gas secretion by fish. AA xl 225. Worm-Miiller 1870 Membranes and transference numbers, PAP cxl 116. Yasuda 1900 Acclimatization. JCS xiii ror. 1900 Turgor regulation. JCS xiii ror. Yatsu 1905 Cytasters in enucleated eggs. JEZ ii 287. Ylupoe 1913 Isoelectric point of casein. ZK viii 224. Zamidzki 1903 Adsorption on foam. ZPkC xlii 612. Zangger 19008 Membranes can act like valves. Alcohol increases permea- bility of yeast to enzymes (144). EP vii 90. Zsigmondy 1906 Colloidal gold. ZPkC Ivi 6s. 1906 Sols without Tyndall phenomenon. ZEC xii 631. 1912 Submicrons in gelatine. KZ xi 145. 1912 “Kolloidchemie” (p. 249). 4% gelatine submicrons on cooling. 1913 Ultramicroscope. PZ xiv 975. —— & Bachmann 1914 Immersion ultramicroscope. KZ xiv 281. Zuelzer 1907 Addition of sea water stops contractile vacuole. Sitzh. Ges. Natf. Freunde. 90. INDEX TO LITERATURE LIST GENERAL: Abderhalden, Asher and Spiro, Bayliss, Griffiths, Hamburger, Hammersten, L. Henderson, Héber, H. C. Jones, Jordan, Koeppe, Lan- dolt-Bornstein, Lusk, McClendon, McKenzie, Matthews, Mellor, Nageli, Nagel, Neuberg, Nernst, Oppenheimer, Wm. Ostwald, Ostwald-Luther, Philip, Putter, Starling, Tigerstedt, Turner, Washburn, Walker, Winter- stein. ABSOLUTE WEIGHT oF MotecuLes: Perrin. : ApssorPTion: Durig, Fleisher and Loeb, Friedenthal, Hamburger, Hober, Muller, Reid, Webster, Wesley. Aciposis: Allen, Higgins and Means, Howland and Marriott, Masel, Novac, Leimdérfer and Porges, Packard, Peabody, Polanyi, Porges, P,, Leimdorfer and Markovici, Poulton, Reicher, Rolly, Ryffel, Sellards, Szili, Underhill. ADAPTATION: Loeb and Wasteneys, Schneider, Urano, Yasuda. ADSORPTION: Barger and Starling, Evans, Herzog and Betzel, Lewis, Liebreich, Michaelis and Ehrenreich, Milner, Morawitz, Wo. Ostwald, Paul, Birsetin and Reuss, Roentgen and Schneider, Rona and Michaelis, Stadler and Kleeman, Straub. Ap.-Compounps AND Cottom REACTIONS: Iscovesco, McClendon, Noguchi, Windaus, Ransom. Ap. oF CoLLomps: Dawe, Hedin, Landsteiner and Uhlirz, Michaelis, M. and Rona, Porter, Quincke, Schmidt-Nielson. Ap. ann Exrectric CHarce: Bayliss, Pelet- Jolivet and Anderson. Ap. on Foam: Benson, Szyszkowski, Zawidzki. Ap. AND SuRFACE TENSION ForMULA: Duclaux, Freundlich, Kuster. Ap. SATURATION: Marc, Schmidt. Ap. anp Sotmp Sotution: Davis, Marc, Titoff, Traube. Competitive Ap.: Biltz and Steiner, Freundlich and Losev, F. and Neumann, Harris, Jahnson-Blohm, Lachs and Michaelis, Michaelis and Rona, Rona and Tosh, Van Bemmeln. AmeEBorin Motion: Bernstein, Hirshfeld, McClendon, Montgomery, Rhumbler, Ross. ALIMENTARY TrAcT: Embden and Kraus, Pavloff. AnestHetics: Boothby, Carlson, Frey, Fihner, Hamburger and de Haan, Johannsen, Lee, L. and Salant, Meltzer and Auer, Meyer, Overton, Otto, Salzmann, Traube. AN. anp Cetis: Gros, Lillie. Aw. anp CoL- Loins: Calugareanu, Goldschmidt and Pribram, Koch and McLean, Lillie, Moore and Roaf, Pribram. An. anp Oxmpation: Alexander and Cserna, Burker, Mansfeld, Meyerhof, Nothmann-Zuckerkandl, Tashiro and Adams, Vernon, Verworn, Warburg. AN. AND PERMEABILITY : Hober, Joel, Lillie, McClendon, Meyer, Osterhout. Srorace or An.: Choquard, Mansfeld. Antitoxic ACTION: Henderson, Ishikawa and Lowi, Lillie, Robertson. ARTIFICIAL MEMBRANES: Zangeger, Bartell, Bayliss, Bein, Bigelow and Bartell, W. Brown, Harvey, Lepeschkin, Meigs, Morse and Horn, Nathan- aoe Wm. Ostwald, Pascucci, Ruhland, Tamman, M. Traube, Worm- Muller. ARTIFICIAL PARTHENOGENESIS: Bataillon, Delage, Glaser, Harvey, Lillie, Loeb, McClendon, Morse, Robertson, Traube. AUTOCATALYSIS ! Herzog, Hoyler, Philoche, Tanaka, Vernon. Autotysis: Benson and Wells, Bradley and Taylor, Chiari, Grode and Lesser, Lyon and Shackell, Morse. BiogrLectric PHeNnomENA: Bernstein, Beutner, Boruttau, Briinings, INDEX TO LITERATURE LIST 236 D’Arsonval, Galeotti, Garten, Hyde, Mathews, Oker-Blom, Tschagowetz. . P. or Granps: Cannon and Cattell. B. P. or Heart: Fleischhauer, Hirschfelder, Straub. B. P. or Muscite: Frolich and Meyer, Pauli and Matula, Piper, Van Brucke. B. P. or PLrants: Burdon-Sanderson, Loeb and Beutner, Waller. B. P. or Skin: Hober, Lesser, Schwartz. Bioop: Barcroft, Abderhalden, Bohm, Denis, Dreyer and Ray, Erb, Heller, Keith, Rowntree and Geraghty, McClendon, Magnus, Pascucci, Plesch, Scott. Coacuiation or B.: Deetjen, Franz, Haycraft, Hekma, Howell, Pekelharing, Ringer and Gainsbury. B. Gases: Barcroft, Chris- tiansen, Douglas and Haldane, Haldane, Hill, H. and Nabarro, Krogh and Krogh, McClendon, Murlin, Edelmann and Kramer, Nicloux, Van Slyke, Cullen and Stillman. Ionrc ExcHance with B. Corpusctes: Ham- burger, H. and Van Lier, Koeppe, Spiro and Henderson. Brownian Movement: Einstein, Perrin, Svedberg. Burrers: Bugarszky and Liebermann, Clark and Lubs, Corral, David- sohn, Friedenthal, L. Henderson, H. and Spiro, Hoffmann, Levy and Rowntree, Palitzsch, Prideaux, Szili and Friedenthal. CatomeL Exscrrope: Auerbach, Lipscomb and Hulett, Loomis and Acree, McClendon, Richards. CALoRIMETRY: Bohr and Hasselbach, Glaser, Hill and Wezsacker. Carson DioxipE: Auerbach and Pick, Boothby and Peabody, Findlay, L. Henderson, H. and Black, Hooker, Johnston, Krogh, Lowy and Zuntz, McClendon, McCoy, Momose, Thiel and Strohecker, Warburg. ALVEOLAR CO,: Begun, Hermann and Munzer, Higgins. CaTaLyzers: Bredig, B. and Fajans, Dietz, Ernst, Faraday, Frankforter and Kritchensky, Heimrod, Kastle, Meyerhof, Nielsen, Schoebein, Stieg- litz, Traube. ; Ceti, Division: Baltzer, Bonnevie, Child, Conklin, Fischel, Gallardo, Gardiner, Lillie, Loeb, L. and Wasteneys, Lyon, McClendon, Mathews, eheasnh Richards, Robertson, Schimkewitsch, Von Erlanger, Warburg, atsu. Cett Structure: Chambers, Conklin, Fischer, Gardener, Gerassimow, Goldschmidt and Poppoff, Hamburger, Hardy, Kohler, Warburg. Centriruces Banta and Gortner, Grijns, Hamburger, Hedin, Koppe, McClendon, Van Calcar and Loby de Bruyn. CHANGES IN PERMEABILITY: Garmus, Léwe, McClendon, Mayerhoffer and Stein, Stewart, Sziics. C. I. P. or Eaes: Gray, Lillie, Loeb, Lyon and Shackell, McClendon. C. I. P. or Muscte: Hober. C. I. P. or Nerve: Bernstein. C. I. P. or PLants: Fernbach, Fliri, Kisch, Lepeschkin, Oster- hout, Pantanelli, Sziics, Trondle Citra: Hober, Lillie, Maxwell, Weinland. Cottoips: Bechhold, Freundlich, Jordis, Krafft, Lottermoser and Rothe, Osborne, Wo. Ostwald, Pauli, Ruhland, Svedberg, Taylor, Zsigmondy. CoacuLaTIon oF C.: Bovie, Buxton and Rahe, Buxton and Shaffer, Chick and Martin, Hardy and Whetham, Harlow and Stiles, Jorissen and Woudstra, Pascheles, Pauli, Quagliariello, Shaklee and Meltzer. Gerza- TIon oF C.: Heilbrunn, Walpole. Precrprration oF C.: Batelli and Stern, Billiter, Freundlich, Freundlich and Schucht, Friedemann and Friedenthal, Hofmann, Landstein and Jagic, Mathews, Michaelis and Rona, Paine, Pauli, P. and Fletcher, Porges and Neubauer, Schulze, Whitney and Ober, Wilke and Meyerhof. Sorazion or C.: (Hardy, Lottermoser. FREezinc- Out or C.: Fischer and Jensen, Lottermoser. Prorection-C.: Faraday, Schaffnit. f CoNcCENTRATION CrLts: Abegg, Auerbach and Luther, Bates, Bennett and Cole, Beutner, Bjerrum, Bugarsky, Cremer, Cummings and Gilchrist, Cybulsky, C. and Dunin-Borokowski, Drucker, Haber and Klemensiewicz, Henderson, McInnes, Mines, Nernst, N. and Riesenfeld, Planck, Tower. Conpuction oF Excitation: Bose, Carlson, Fitting, A. V. Hill, Keith 236 INDEX TO LITERATURE LIST a Flack, Lapique and Legendre, Lillie, Lodholz, Lucas, McClendon, ayer. CoNTRACTILE VAcuoLte: Rhumbler, Stempell, Zuelzer. Cytotysts: Lillie. Density: Lyon, Traube. Desiccation: Becquerel, Dreyer and Walker, Jacobs, Shattock and Dudgeon, Whitney. Dirrusion: Abel, Rowntree and Turner, Bechhold and Ziegler, Ham- burger, Hedin, Héber, Michaelis and Rona, Rona and Gyorgy, Scheffer, Wallace and Cushny. D. or Cottoms: Flexner and Noguchi, Graham, Herzog and Kasarnowski, Mayerhofer and Pribram. oo or AmpHotytes: Bredig, Kanitz, Lunden, Robertson, ood. DisinFEcTION: Clark, Czapek, Dreser, Eisenberg and Okoloska, Kahlen- berg, K. and Austin, K. and True, McClintic, Mathews, Morawitz, Norton and Hsu, Nothmann-Zuckerkandl, Paul, P. and Kronig, Pulst, Scheurlin, S. and Spiro, Spiro and Bruns, Stevens, True. Dynamic Action or Protein: Lusk, Williams, Riche and Lusk. Exectric CHARGE: oF CELLs: Cernovodeanu and Henri, Henri, Hoéber, Teague and Buxton, Thornton. E. C. or Cotroms: Billiter, Biltz, Bot- tazzi, Burton, Buxton, Shaffer and Teague, Coehn, Freundlich and von Elissafoff, Henri and Mayer, Iscovesco, Knoblauch, Lewis, Linder and Picton, Luther, Peckelharing and Ringer, Perrin, McClendon, Pauli, Von Elissafoff and Freundlich, Walker and Marshall, Whitney and Blake. E. C. or Protoprasm: Brown, McClendon. Exectric Conpuctivity: Bugarsky and Tangl, Harris and Gortner, Noyes, N. and Melcher, Cooper and Eastman, Oker-Blom, Washburn and Bell. E. C. or Cetts: Brown, Franckel, Gray, Hober, McClendon, Stew- art. i E. C. or Tissues: Du Bois-Reymond, Galeotti, Kodis, McClendon, Waller. Exectric Orcan: Bauer, Bernstein and Von Tschermak, Dahlgren, Garten. Exectric PoLarizATION oF MEMBRANES: Bancels, Bayliss, Bethe and Toropoff, Beutner. ELectRoENDosMosE: Bethe, Bournat, Byers and Walter, Von Elissapoff, Wiedemann, Windle. Exectrove PotrentiaL: Abl, Billiter, Nernst. Eectrotytes: Rona, R. and Michaelis, R. and Takahashi, Winkleblech. Exectrotytic Dissociation: Arrhenius, Bousfield, Denham, Ellis, His and Paul, Millikan, Noyes and Blanchard, Wm. Ostwald, Rudolphi, Scud- der, Van’t Hoff, Walker and Cormack, Wood. Extecrrotytic Sotution TENsIon: Bechhold, Haber, Heald, Lewis and Keyes, L. and Rupert, McGuigan, Mathews, Michaelis, Nernst. ELECTROMETERS AND GALVANOMETERS: Burch, Einthoven. Emutsions: Iscovesco, McClendon. Emutsoiws: Galeotti, Hatschek, Traube and Kohler, Van Bemmeln. Enzymes: Euler, Bradley, Emmerling, Falk and Nelson, Frankel, Hud- son, Koopman, Lyon, McClendon, Mayer, Meyer, Morse, Oppenheimer, Pierce, Porter, Schutz, Sedgwick and Schlutz, Slator, Van Slyke and Cullen, Warburg. E. anp Asymmetry: Abderhalden and Guggenheim, A. and Pringsheim, Bayliss, Dakin, Erlenmeyer, Bredig and Fiske, Fajans, Fischer, F. and Abderhalden, Herzog and Meier, Pasteur. E. Inuzsrrors: Abderhalden and Gigon, Armstrong, Bigelow, Burge, Cathcart, Hammill, Hedin, Michaelis and Menten, Pfeffer and Hansteen, Richards, Souza, Vernon, Walters. E. anp Surrace PHENomMENA: Beard and Cremer, Goldschmidt, Meyerhof, Waentig and Steche, Warburg and Wiezel. FE. Synruesis: Armstrong, Bradley, A. C. Hill, Kastle and Loevenhart, Rosenthaler, Rubner, Taylor. INDEX TO LITERATURE LIST 237 Eguitisrium Point: Knupfer and Bredig, Wm. Ostwald. E. P. or Enzymes: Acree and Johnson, Bodenstein and Dietz, Euler. Excitazitity: Joseph and Meltzer, Overton, Koltzoff, Schwarz. Excretion: Asher and Waldstein, Bainbridge Collins and Menzies, Barcroft and Brodie, B. and Straub, Barlow, Beddard, Bock and Hoff- mann, Burian, Carrel and Guthrie, Cushny, Ghiron, Hober and Konigs- berg, Knowlton, Nishi, Pototsky, Ribbert, Ringer, Sollman. Exupates: Chiari and Januschke, Januschke. FertTitization: Bachmann and Runnstrom, Glaser, Jacoby, Lillie, Loeb, McClendon, M. Morse. FERTILIZATION Memprane: Harvey, Heilbrunn, Herbst, McClendon, Schucking. Firtration: Bigelow, Heymans, Lottermoser. Freezinc Point: Burian and Drucker, D’Arsonval, Garrey, Gortner and Harris, Harris and Gortner, Loomis, MacCallum and Benson, Sab- batani, Toda and Taguchi, Urano, Widmark. F. P. or Brioop: Botazzi, B. and Ducceschi, Buglia, Carlson, Greer and Luckhart, D’Errico, Dek- huisen, Fano and Botazzi, Franz, Hober, Von Koranyi, Kovacs, Nolf, Phillipson Hennevart and Thieren, Portier, Quinton, Rodier. F. P. or Fish: Greene, Loeb and Wasteneys, G. Scott, Sumner. F. P. or Boop oF Mammats: Atkins, Salge, Schulz, Van der Laan. F. P. or Ecos: Backman, B. and Runnstrom, B. and Sundberg, Bialaszewicz. F. P. oF Prants: Atkins, De Vries, Fitting, Gortner and Harris, Harris and Gortner. GrowtH: Congdon, Davenport, Donaldson, Frozee, Gager, Harrison, Hyde and Sprier, Jackson. Haprocen Mrmpranes: Hofmann, Lewis, Metcalf, Pickering, Rams- den, Rohde, Schutt, Shorter. Heart: Busquet and Pachon, A. J. Clark, Mines, Ringer. Hemotysis: Stewart, Fihner and Neubaur, Girard, Gros, Guthrie, Hamburger, Handowsky, Hirschfeld, Hober, H. and Nast, Kyes, Mc- Phedran, Michaelis and Takahashi, Miculicich, Neufeld and Handel, Noguchi, Port, Roaf, Rywosch, Traube, Von Dungern and Coca, Woelfel. Herepity: Gregor Mendel, Tennent. Hypration: H.C. Jones, Lewis, Pauli and Falek. Hyprocen Etrectrope: Clark, Hemptinne, Hoitsema, Lewis and Lacey, McClendon, Mond, Ramsay and Shields, Myers and Acree, Richardson Nicol and Parnell. Hyoprocen Jon Concentration: Emsilander, Hasselbalch, Henze, Herbst, Howe and Hawk, Marriott, Michaelis, Okada, Schmidt, Sorensen, Wal- pole. PH or Bacteria, CuLtturE Mepia: W. M. Clark,.C. and Lubs. PH or Broop: Agazzotti, Benedikt, Bottazzi and Craifaleanu, Farkas, F. and Scipiades, Friedenthal, Hasselbalch and Lundsgaard, Henderson, Hober, Konikoff, Kreibich, W. Loeb and Higuchi, Lundsgaard, Mathison, McClendon, Menten and Crile, Milroy, Mines, Pfaundler, Quagliariello, Rowntree, Marriott and Levy, Salge. PH anp Enzymes: Allemand, Auerbach and Pick, Compton, Davidsohn, Fernbach, Hudson, Huenekens, Kanitz, Palitzsch and Walbum, Ringer, R. and Van Trigt, Sorensen, Tanaka, Van Slyke and Zacharias, Wantig and Steche. PH or Urine: Henderson, Héber and Jankowsky, Rossi. Hyoprotytic Dissociation: Shields. Hysteresis: Danysz, Freundlich. Immune Bonres: Biltz, Bordet, Beniasch, Bernstein and Simonds, Craw, Eisenberg and Volk, Field and Teague, Porges, Teague and Buxton. Ions, Action or: Beneche, Eisler, R. Ellis, Forster, Frey, Gray, Griin- wald, Guthrie and Ryan, Herbst, Loeb, Mathews and Brooks, Mines, Morgan and Stockard, Osterhout, Ringer and Phear, Spaeth, Von Wyss. Antaconistic Action oF I.: Bernoulli, Fischer, Freund, Galeotti, Linder 238 INDEX TO LITERATURE LIST and Picton, Loeb, L. and Cattell, L. and Gies, Loew, Meltzer and Auer, Osterhout, Spaeth. Ionic Sprep: Bredig, Kohlrausch. lon-ProteIn Compounps: Cohnheim, Handowsky, Manabe and Matula, Pauli and Handowsky, Pfeiffer and Von Modelsky, Rohonyi, Rona and Gyorgy, R. and Takahashi, Simon. : Inpicators: Fowler, Bergeim and Hawk, Friedenthal, Harvey, Levy, Rowntree and Marriott, Lubs and Clark, McClendon, Michaelis and Davidsohn, Wo. Ostwald, Palitzsch, Salm, Scatchard and Bagert, Séren- sen and Palitzsch, Walbum. Inuipition: Chiari and Frolich, Gaskell, Hagglund, Hagan and Or- mond, Hering, Howell and Duke, Meek and Eyster. oo Cohnheim, Hooker, Quagliariello, Rona and Neukirk, 'yrode, . IsozLtectric Pornr: Buglia, Hardy, Kozawa, Landsteiner, Michaelis, M. and Davidsohn, M. and Rona, Schorr, Ylupoe. Licut Perception: Eldridge-Green, Hartridge, Henri. Lympu: Heidenhain, Leathes. . Lyotropic Series: Bechhold, Gouy, Griitzner, Hober, H. and Walden- berg, Hofmeister, K6lichen, Loeb and Wasteneys, McIntosh, Pauli, Schade, Washburn, Wilsmore. Mass Action Law: Guldberg and Waage. ‘Micro Anatysis: Hamburger, A. B. Macallum, McDonald. Mirx: Abderhalden, Burri and Nussbaumer, Davidsohn, Friedenthal. Muscie, SmootH: Fienga, Trendelenberg, Meigs, M. and Ryan, Pug- liese. Strratep M.: Ho6ber and Spaeth, Mines, Beccari, Jensen and Fischer, Katz, Meigs, Von Fiirth and Lenk, Winterstein. M. Conrrac- TION: Benedict and Cathcart, Berg, Bernstein, Cohnheim and von Uexkull, Cooke, Du Bois-Reymond, Ebbecke, Embden and Kondo, Engelmann, Fletcher, F. and Brown, A. V. Hill, Héber, Macallum, McClendon, Mc- Dougall, Meigs, Overton, Pauli, Ringer, Roth, Schwarz, Straub. Necative Osmose: Bartell, B. and Hocker, Cohnheim, Dutrochet, Flusin, Freundlich, Girard, Graham, Hamburger, Heidenhain, Reid. NEPHELOMETER: Richards, R. and Wells. Nerves: Alcock and Lynch, Baeyer, Griitzner, Lodholz, Lucas, Mathews. Non-E.ectrotytes: Gudzent, Loeb, Moruzzi, Temple. Optica Rotation: Pauli, Samec and Strauss. Osmosis: Aubert, Bartell. Osmotic Pressure: Findlay, Arrenhius, Barger, Berkley and Hartley, Clowes, Friedenthal, Hedin, G. N. Lewis, Loeb and Wasteneys, H. N. Morse, Pfeffer, Ramsay, Raoult, G, G. Scott, Stern, Sumner, Tamman, Van’t Hoff. O. or Cottors: Bayliss, Biltz, Donnan, D, and Harris, Ducceschi, Duclaux, Gatin-Gruzewska, Lillie, Moore and Roaf, Reid, Roaf, Starling. O. Recutation: W. J. Dakin, Fredericq, Garrey, Henri and Lalou, Mayenburg, Mouton, Overton, Pantanelli, Quinton, Schmidt-Niel- sen, G. G. Scott, Sumner, Van Rysselberghe, Yasuda. OxyYHEMOGLOBIN: Barcroft and Camis, B. and Hill, Bohr, Donders, Douglas, Freundlich and Bjercke, Haldane and H., A. V. Hill, Hiifner, H. and Gansser, Wo. Ostwald, Scott. Oxipation: Ehrlich, Banta, Brodie and Vogt, Drury, Fenton, Hyman, Krogh, McClendon, Mathews, Murlin and Kramer, Onaka, F. H. Scott, Thunberg, Warburg, Widmark, Winterstein, Wolff. O. anp ANESTHETICS: Batelli and Stern, Vernon, Warburg, Winterstein. O. rn Cretts: Batelli and Stern, Child, Harden and McLean, Heilbrunn, Héber, Itami and Pratt, Lillie, Loeb and Wasteneys, McClendon and Mitchell, Meyerhof, Moldovan and Weinfiirter, Morawitz, Schlapper, Tangl and Farkas, Tashiro, Wachendorff, Warburg, W. and Meyerhof, Wasteneys. O. En- zymes: Bunzell, H. D. Dakin, Kastle, Bach and Chodat, Engler and Wild, INDEX TO LITERATURE LIST 239 Herzog and Meier, Moore and Whitley, Reed, Trillat, Vernon, Warburg, W. and Meyerhof. O. ann Oxycen Pressure: Bert, Demoor, Fallois, Henze, Lehmann, Loeb and Wasteneys, Mitscherlich, Piitter, Roaf, Tor- rey, Verzar. O. anp PH: Mathews, McClendon and Mitchell, Warburg. O. 1n Tissues: Batelli and Stern, A. V. Hill, Verzar. O. 1n CrusHep Cetts: Batelli and Stern, Biichner and Rapp, Bunzel, Fletcher and Hop- kins, Meyerhof, Warburg. Partition CorFFIcieNtT: Berthelot and Jungfleisch, Lowy, H. Meyer, Overton, Pohl, Reinders, Usui. PerMEABILITY: Bartell, Bayliss, Bechhold, Bethe, De Vries, Endler, Harvey, Hoéber, Katzenellenbogen, Kite, Kuhne, L’Hermite, Loeb, Mag- nus, Sorgdrager and von Leeuwen, Mathews and Longfellow, Nernst, Overton, Riddle and Spohr, Rost, Schiiking, Sziics, Walden. P. oF BLoop VESSELS: Magnus, F. H. Scott. P. to Dyes: Eisler and von Portheim, Bethe, Evans and Schulemann, Hober. and Kempner, Kuster, Lowe, Michaelis and Davidsohn, Schulemann, Traube. P. or Eccs: Brown, Harvey, Loeb, McClendon, Overton, Sollman. P. or ErytTHrocyTEs: Calugareanu and Henri, Constantino, Hamburger, Hedin, Héber, Kozawa, Masing, Moore and Roaf, Rona and Doblin, Rona and Takahashi, F. H. Scott, Stewart. P. or Granps: Asher and Karaulow, Siebeck. P. oF Muscie: Fahr, Jacoby and Golowinski, Meigs, Overton, Siebeck, Urano. P. or Prants: Fischer, Harvey, McClendon, Merril, Osterhout, Over- ton, Paine, Wachter. P. or Sreps: Atkins, A. Brown, Shull Pertopiciry: Bohn, Bredig, B. and Weinmayr, F. Darwin, Kister, - Liesergang, Lyon. Puacocytosis: Hamburger, H. and de Haan, H. and Hekma, Koltzoff, L. Loeb, Prowazek, Rhumbler, Savchenko and Aristovsky, Voigt. PoTtENTIOMETER: Bovie, McClendon. PHoTocGENEsIs: ‘Callaud and Pelletier, Coblentz, Dubois, Harvey, Radziszewski, Stubel, Trautz. / PuotosyntHesis: Allen, Biltz, Berthelot and Gaudechon, Bodenstein, Bunsen and Roscoe, Gibson and Titherly, Hallwachs, Hughes, Luther and Forbes, B. Moore, M. and Webster, Schryver, Sheppard, Usher and Priest- ley, Wagner, Warner. PHYSIOLOGICAL OR PerFusIon Friuips AND Cet, Mepia: Gothlin, Her- litzka, Lewis, Locke, Raulin. PH or P.: Mines, Rona and Wrlenko, Schwartz and Lemberger, Schwyzer. Piant MoveMeENTs: Bose, Pringsheim, Ewart. PrasMA MempraNeE: Kuster, Lepeschkin, Prowazek, Quincke. Ee oie Bartetzko, Hamburger, Osterhout, Overton, Schwellen- grebel. PsycHOGALVANIC ReFLEx: Gildemeister, Salamonson. ReFRacTioN: Pearl and Gowan, Botazzi. REGENERATION: Cary, McCallum, Moore. ResprrAToRY CENTER: Campbell, Douglass, Haldane and Hobson, D., H., Henderson and Schneider, Gasser and Loevenhart, Haldane and Priestley, Hasselbalch, Milroy, Porges, Winterstein. Resistance: Hutchison, Wo. Ostwald, Pictet, Thistleton-Dyer. Sea Water: Allen and Nelson, Bethe, Clarke, Dittmar, Dole, Drew, Forschhammer, Krogh, Macallum, Matthews, Palitzsch, Raben, True. Secretion: Bainbridge, Benrath and Sacs, Bergeim, Bohr, Botazzi and Enriquez, Fitzgerald, Mendel and Thatcher, Woodland. Sotusitity: Bechhold and Ziegler, Bodlander and Fitting, Gudzent, Hulett, Wm. Ostwald, Pauli and Samec, Philip, Schade, S. and Boden, Vernon, Winterstein. Strmutation: Adrian, Bethe, Chapin, Erlanger and Garrey, A. V. Hill, Hober, Lapique, Lillie, Loeb and Ewald, McClendon, Mathews, Nernst, N, and Barratt, Von Zeynek and von Bernd Verworm, Warburg. 240 INDEX TO LITERATURE LIST StomacH: Cannon, Carlson Orr and Brinkman, Davidsohn, Hess, Rehfuss, R., Bergeim and Hawk. PH or S. Contents: Boldyreff, Frankel, McClendon, Menten, Michaelis and Davidsohn, Rehfuss and Hawk, Tangl, Von Jaksch. Surrace Tension: Allen, Berczeller and Csaki, Billird and Bruyant, B. and Dieulafe, Botazzi, Colton, Cramer, Davis, Donnan and D., Duclaux, Dupré, Fanno and Mayer, Frenkel and Cluzet, Gibbs, W. J. Jones, Harkins and Humphrey, Kaufler, Kisch, W. “Lewis, Macallum, McClendon, Michaelis, Morgan, Quincke, Rayleigh Traube Whatmough. S. T. oF Cottows: Berczeller, Botazzi. Suspensions: Einstein, Freundlich and Makelt, Perrin, Spring. SuspPensoips: Barus, Bredig, Duclaux, Svedberg, Zsigsmondy. SPERMATOZOA: De Meyer, Hirokawa, Koltzoff, F. Lillie. Swe.urne: Fischer, Demoor, Goodridge and Gies, Loeb, Meigs, Meyer and Cohn, Nasse, Schaper, Schloss, Traube and Marusawa. S. or Cot- Loips: Beutner, Chiari, Ehrenberg, Fischer and Moore, F. and Sykes, Hauberisser and Schonfeld, Henderson, Palmer and Newburgh, Lewites, Ludwig, Pauli and Rona, Posnjak, Samec, Schade, Spiro, Wiedermann and Ludeking. Osmotic S.: Beutner, Bialaszewicz, Hirokawa, McClen- don. Turcor: Correns, Massart. SyntHesis: Kolichen, Loew. (See Enzymes.) TEMPERATURE COEFFICIENT: Bernstein, Clausen, Ganter, Kanitz, Krogh, a Masing, A. G. Mayer, A. Moore, Snyder, Van Rysselberghe, Von alban. THERMODYNAMICS: Bernstein, Dupré, Gibbs, Lewis and Randall, Meyer- hof, Verzar. Tropisms: Jennings, Loeb. Gatvano T.: Bancroft, Cohn and Barrat, Dale, Gassner, Greely, Loeb and Budgett, Ludloff, Mendelssohn. Geo T.: Czapek, Haberlandt, Kanda, Lyon, McClendon, Nemec. Puoro T.: Ewald, Engelmann, Loeb, L. and Wasteneys, Mast. Rueo. T.: Allee, A. and Tashiro, Allen, Lyon. aa PHENOMENON: Picton and Linder, Rayleigh, Tyndall, Zsig- mondy. ULtrAFILTRATION: Bechhold, Burian, Hatschek, Ruhland. / ULTRAMIcRoscopy: Bachmann, Cesana, ‘Cohn, Donnan and Potts, Gatin-Gruzewska and Biltz, Hober, Le Blanc, Linder and Picton, Menz, Michaelis and Pincussohn, M. and Rona, Perrin, Price, Rahlmann, Sieden- topf and Zsigmondy, Stitbel, Teague and Buxton, Von Veimarn, Zsig- mondy, Z. and Bachmann. UnpercooLinc: Bachmetjew, Kodis, Muller-Thurgau. Vasomotor CENTER: Mathison, Sollman and Pitcher. Viscosity: Arrenhius, Wo. Ostwald, Sziics, Traube, Wagner, White. V. or Bioop: Albutt, Austrian, Bayliss, Boveri, Burton-Opitz, Heubner, McCaskey. V. or Cottorps: Bingham and Durham, Hatschek, Laquer and Sackur, Michaelis and Mostynski, Pauli and Samec, P. and Wagner, Thomas, Traube, Von Schroder. Water: Armstrong, Bousfield and Lowry, Guye, Hulett, Kohlrausch and Heydweiller, Krogh, Lowe, Lowenherz, Lorenz and Boehi, Roaf, Sérensen and Palitzsch, Wijs. Weston Cett: Rosa, Wolff. Seen