GIFT OF 
 
HEALTHFUL LIVING 
 
p. 
 
 THE MACMILLAN COMPANY 
 
 NEW YORK BOSTON CHICAGO DALLAS 
 ATLANTA SAN FRANCISCO 
 
 MACMILLAN & CO., LIMITED 
 
 LONDON BOMBAY CALCUTTA 
 MELBOURNE 
 
 THE MACMILLAN CO. OF CANADA, LTD, 
 TORONTO 
 
HEALTHFUL LIVING 
 
 BASED ON THE ESSENTIALS OF PHYSIOLOGY 
 FOR HIGH SCHOOL PUPILS 
 
 BY 
 JESSE FEIRING WILLIAMS, A.B., M.D. 
 
 ASSOCIATE PROFESSOR OF PHYSICAL EDUCATION, TEACHERS COLLEGE 
 
 COLUMBIA UNIVERSITY 
 FORMERLY PROFESSOR OF HYGIENE AND PHYSICAL EDUCATION 
 
 UNIVERSITY OF CINCINNATI 
 LIEUTENANT IN MEDICAL CORPS, UNITED STATES ARMY 
 
 Illustrations by B. F. Williamson 
 
 Nefo gorfc v 
 
 THE MACMILLAN COMPANY 
 1921 
 
 All righto reserved 
 
QP.3& 
 
 COPTBIOHT, 1919, 
 
 './i b^THE MACMILLAN COMPANY. 
 S^ vi^nd eicctrotyped. Published July, 1919. 
 
INTRODUCTION 
 
 IN writing this book, I have been guided by two con- 
 siderations : first, to present the essentials of physiology 
 for the high school pupil in a form that would provide 
 motives and material that would enable him to interpret 
 intelligently conditions underlying the problem of effective 
 living, and second, to limit the technical discussion without 
 making the subject matter worthless as a scientific text, 
 incapable of providing the background necessary to secure 
 the first consideration. 
 
 As regards the limiting of material, it is evident that the 
 selection of what to give and what to omit is a matter of 
 judgment on the part of the author. If that judgment is 
 to be approved by the educational world interested, then 
 the anatomy should have a definite relation to the physiology, 
 and the physiology, although it may give incidentally a 
 scientific basis for more advanced study, should be deter- 
 mined by the larger question of usefulness in understanding 
 essential life processes. 
 
 The material and the method of presentation have been 
 tried out for several years with many students and there is 
 reason for feeling that a proper and satisfactory selection of 
 physiologic facts and principles has been made. 
 
 It is interesting to note that at one time physiology in the 
 schools was merely the teaching of anatomy. "How many 
 bones in the skeleton?" was a typical question. As the 
 texts improved and the method changed, function was 
 emphasized, and in most texts to-day, the presentation of 
 
 v 
 
 450954 
 
vi Introduction 
 
 function is the goal of endeavor. It should be remembered, 
 however, that knowledge of the structure and function of the 
 body is of value in proportion as it helps the boy or girl to 
 live a finer and more vigorous life, or as it lays the foundation 
 for further study in this field. As regards these values, it 
 may serve effectively to teach not only hygiene, but also 
 social science and ethics. 
 
 The study of physiology should arouse interest in health 
 in the student and provide guidance for intelligent care of 
 the body. One effect of civilization on the race is that 
 health is increasingly harder to maintain. The gradual 
 but pronounced change in the character of our food, the 
 increasing emphasis laid upon studies, the prevalence of bad 
 housing conditions, the increase in sedentary occupations, 
 and the enforced use of the transportation facilities are a 
 few of the forces arrayed against the maintenance of health. 
 The school does not stand alone and unrelated to these 
 problems, and physiology to be of most service must help 
 to educate the child in the nature of the human body and the 
 dangers that confront its growth, development, and efficiency. 
 
 With this object in mind, distinct emphasis is given the 
 application of the physiological fact to the life of the reader. 
 Therefore, relatively little space is devoted to, the study of 
 the mechanism of the eye and ear ; but the physiology of 
 exercise is stated prominently, both in text and in illustra- 
 tion. The wisdom of such a course will be clear to every 
 one whether he judges by the standards of "pure science" 
 or by those of "applied science." 
 
 Spirited questions, which should suggest many others of 
 similar character, are placed at the end of chapters. There 
 are numerous laboratory experiments ; most of these require 
 only the simplest apparatus or none at all. The text is not 
 impaired if the experiments are not performed, but its value 
 is increased by the demonstration of both structure and func- 
 tion. At the close of each chapter is a glossary of technical 
 
Introduction vii 
 
 terms used in that chapter. There is no thought of doing 
 away with the need for consultation or reference books ; 
 they are always necessary, and the brief glossary should 
 stimulate to greater use of dictionary and encyclopedia. 
 
 To acknowledge the service of those who have contributed 
 in the preparation of this book, gives me especial pleasure. 
 The organization is based partly on the plan of Coleman's 
 Elements of Physiology. All rights in that work have been 
 purchased by the publishers and this new book is offered to 
 the school public without apology for similarities or identities, 
 which are many. The task was to remodel a structure that 
 had been very valuable but was now in need of repairs. 
 The repairs have been made but it would ill become me to 
 deny the old in my enthusiasm for the new. 
 
 To Miss Marguerite Smith for the picture of girls' athletics, 
 to Miss Mary Gross for excellent illustrations of posture, 
 to Dr. Frank S. Matthews for the splendid pictures of adenoid 
 deformity, to Dr. Thomas D. Wood for numerous health 
 essentials which he has proposed, I desire to express my 
 thanks. 
 
 Students, instructors and friends who have gone over this 
 subject with me share with me whatever merit the book 
 may have, but I desire especially to acknowledge the in- 
 spiration and help of Professor Henry Carr Pearson, prin- 
 cipal of the Horace Mann School. 
 
 The criticism and suggestions of Professor Edward Law- 
 rence Hall-Quest, of the University of Cincinnati, have been 
 valuable indeed. Professor Hall-Quest has read the entire 
 manuscript, correcting mistakes and revising statements. 
 Numerous conferences with Professor William Paxton 
 Burris, Dean of Teachers College of the University of Cin- 
 cinnati have resulted in substantial aid in preparing the 
 manuscript. 
 
 Credit should be given to the Harvard Apparatus Co., 
 The Metropolitan Life Insurance Co., The American Posture 
 
viii Introduction 
 
 League, and The Scientific Temperance Federation for 
 the privilege of reproducing illustrations that have appeared 
 in other publications. 
 
 With such an indebtedness, I hesitate to call the book my 
 own. However, I am glad to owe something to all of these. 
 
 J. F. W. 
 
CONTENTS 
 
 PART I 
 HOW THE BODY IS CONSTRUCTED * 
 
 PTER PAGE 
 
 I. THE CELLS OF THE BODY 1-11 
 
 The cell, the unit of structure. The origin of cells. 
 The properties of cells. Tissues formed from cell groups. 
 Organs formed from tissues. Similarity between living 
 organisms and social groups. Similarity between the 
 human body and a city. 
 
 II. TISSUES 12-37 
 
 Kinds of tissues. Epithelial tissues. Indications of 
 good health. 
 
 III. TISSUES (continued) 38-59 
 
 Connective tissues. Muscular tissues. Nervous 
 tissues. Building good tissues. 
 
 IV. ORGANS FORMED FROM TISSUES .... 60-71 
 
 The different systems in the body. Organs of the 
 muscular system. Organs of the skeletal system. 
 Organs of the digestive system. Organs of the respira- 
 tory system. Organs of the circulatory system. Organs 
 of the nervous system. Organs of the excretory sys- 
 tem. Organs of the reproductive system. 
 
 PART II 
 HOW THE BODY IS MOVED 
 
 V. THE SKELETON FRAMEWORK OF THE BODY ". . 72-94 
 
 The use of the skeleton. Parts of the skeleton. The 
 structure of a long bone. The composition of bone. 
 Joints. 
 
 ix 
 
x Contents 
 
 CHAPTER PAGE 
 
 VI. HYGIENE OF THE SKELETON . . . 95-108 
 
 The nourishment of bones. Broken bones. Dis- 
 locations and sprains. Weak feet. Deformities of the 
 spinal column. Posture. Essential facts in the growth 
 and development of bones. 
 
 VII. THE MUSCLES 'AS THE MOTOR MACHINERY OF THE 
 
 BODY . . r V' 109-121 
 
 What the muscles do. Muscles and nerves. Kinds 
 of muscles. Voluntary and involuntary muscles com- 
 pared. The attachment of muscles. How muscles and 
 bones cooperate. Names and positions of muscles. 
 
 VIII. THE MUSCLES IN ACTION AND THE HYGIENE OF 
 
 EXERCISE 122-145 
 
 The neuro-muscular mechanism. Muscular energy. 
 Muscular tone. Muscular activity and fatigue. The 
 effects of stimulants and narcotics on muscular action. 
 The effect of exercise on growth. The relation of exer- 
 cise to health. Forms of exercise. Over-development 
 .of the muscles. 
 
 PART III 
 HOW THE BODY IS NOURISHED 
 
 IX. FOOD AND ITS ELEMENTS 146-157 
 
 Nutritive and non-nutritive elements in food. Com- 
 position of foods. Sources of food elements. Uses of 
 food in the body. Proportion of food elements in a 
 normal diet. Calculation of food values. The diet of 
 different peoples. The body's method of regulating the 
 food supply. The work of enzymes in digestion. 
 
 X. THE DIGESTION OF FOOD 158-188 
 
 The structure and functions of the alimentary canal. 
 The liver. Diagram of digestive mechanism. The 
 waste products from food elements. 
 
 XI. THE HYGIENE OF DIGESTION . . tt . . . . 189-210 
 
 Digestion and health. Digestion and environment. 
 Hobbies about nutrition. Man's original food re- 
 
Contents xi 
 
 sources and how they have been enlarged. Present day 
 sources of food. Patent medicines. Eating and drink- 
 ing at meals. General rules modified by individual 
 needs. Cooking. The fireless cooker. Times for eating. 
 
 XII. THE CIRCULATION OF THE BLOOD .... 211-234 
 
 How the circulation of blood serves the body. The 
 nature of circulation. The composition of the blood. 
 The heart as a pump. The blood vessels as tubes. 
 Blood pressure. The heart rate. 
 
 XIII. THE CIRCULATION OF THE BLOOD (continued) . 235-255 
 
 How the heart is aided in its work. The lymphatic 
 circulation. Hygiene of the circulation. 
 
 XIV. THE RESPIRATION 256-285 
 
 Why breathing organs are needed. The respiratory 
 organs. The breathing process. The air we breathe. 
 The hygiene of respiration. 
 
 PART IV 
 HOW THE BODY IS CONTROLLED 
 
 XV. THE NERVOUS SYSTEM 286-315 
 
 The functions of the nervous system. The nerve cell 
 the unit of the nervous system. Nerve action. Sensations. 
 Injury to nerves. General arrangement of the nervous 
 system. 
 
 XVI. HYGIENE OF THE NERVOUS SYSTEM . . . 316-331 
 
 Connection between body and mind. The effect of 
 activity of the nervous system. The effect of sleep. The 
 effect of fatigue. The effect of alcohol. Improper func- 
 tioning of the nervous system. Ten Golden Rules of 
 Health. 
 
 XVII. SENSATIONS AND THE SPECIAL SENSES . . . 332-356 
 
 Classification of the senses. The sense of taste. The 
 sense of smell. The sense of sight. The sense of hearing. 
 The sense of touch. The muscular sense. General 
 sensations of the body. 
 
xii Contents 
 
 CHAPTER PAGE 
 
 XVIII. SOME SPECIAL REGULATIVE PROCESSES . . . 357-367 
 
 The regulation of the temperature of the body. The 
 regulation of body activity and growth. The control of 
 the voice. 
 
 PART V 
 HOW THE BODY IS INJURED 
 
 XIX. BACTERIA AND DISEASE ...... 368-399 
 
 Injury to the body by forces in its environment. 
 Microscopic forms of life. The effects of bacterial 
 growth in the body. The germ theory of disease. 
 Anti-toxins and immunity. Injury of the body -by 
 poisons in food. Injury of the body by physical agents. 
 Injury of the body by chemical agents. Diseases caused 
 by mosquitoes. Tuberculosis. Prevention of commu- 
 nicable diseases. Table of ways and means of com- 
 munication of the important infections of man. How 
 bacteria are destroyed within the body. How bacteria 
 are destroyed outside the body. A curious theory of 
 disease. Health rules for school children. 
 
 XX. THE EFFECT OF ALCOHOL AND TOBACCO . . 400-416 
 
 The body as a storehouse of energy. The meaning of 
 fatigue. The effect of stimulants on energy and nerves. 
 Alcohol. Tobacco. 
 
 APPENDIX. FIRST AID IN EMERGENCIES 417-426 
 
HEALTHFUL LIVING 
 
HEALTHFUL LIVING 
 
 CHAPTER I 
 THE CELLS OF THE BODY 
 
 I. The Cell, the Unit of Structure. 
 Protoplasm 
 Nucleus 
 
 One-celled animals 
 II. The Origin of Cells. 
 
 III. The Properties of Cells. 
 
 IV. Tissues Formed from Cell Groups. 
 V. Organs Formed from Tissues. 
 
 VI. Similarity between Living Organisms and Social Groups. 
 One-celled animals and primitive society 
 The developed body and modern society 
 VII. Similarity between the Human Body and a City. 
 
 The cell, the unit of structure. A brick wall is con- 
 structed from bricks. Assembled in a certain order, they 
 are the parts which compose the wall. It makes no dif- 
 ference whether the brick is round, square, or irregular, 
 whether it is painted red, green, or blue ; it remains, in all 
 cases, the unit out of which the wall is built. Consequently 
 we speak of the brick as being the unit of structure of the 
 wall (Fig. 1, A). In similar fashion, all forms of life are 
 composed of cells. Plants and animals are both constructed 
 from cells. They may vary in shape, size, color, and ac- 
 tivity, but, nevertheless, they are to be considered as the 
 units of structure. These units are so small that they can 
 be seen only by means of the microscope, but when we look 
 
-Healthful Living 
 
 FIG. 1. A, brick wall ; B, segment of orange ; 
 C, cells from stomach. The cell is the unit of struc- 
 ture. Relative size is not shown. The cells in C 
 are much smaller than the cells in B. 
 
 at them through this instrument, we notice that they are 
 as definite in shape as the bricks in a brick wall (Fig. 1, C). 
 
 The cells of 
 
 3 0123^^ ^j^M^^ P lant and animal 
 
 are not hard and 
 solid as bricks 
 are. On the con- 
 trary, they are 
 soft and liquid. 
 It is quite com- 
 mon to think of 
 an orange as a 
 solid substance, 
 and yet the 
 orange is composed of cells which are filled with a liquid, 
 the juice. If we break open the segment of an orange, 
 we can see the cells with the unaided eye, and if we prick 
 one of them the juice will run out (Fig. 1, B). 
 
 Protoplasm* The liquid substance of which the body 
 cell is made is called protoplasm, and this name is applied 
 to the cell substance of both 
 animals and plants. Workers 
 with the microscope, many 
 years ago, found that plant 
 and animal tissues are com- 
 posed of cells, and that the 
 liquid in the cells is of more 
 importance than the walls F[G 2 _ Diagram of . coll 
 
 Which the protoplasm builds Showing that protoplasm has an 
 around itself. intricate structure; in this case it 
 
 appears somewhat like honeycomb. 
 
 We should not think be- 
 cause we use the same name, protoplasm, for the substance 
 forming the cellular material of both plants and animals, 
 
 * Words marked with a star * are defined in the glossary at the end of each 
 chapter. 
 
 Nuc/eofus 
 Protoplasm 
 
The Cells of the Body 
 
 that its chemical composition is always the same (Fig. 2). 
 
 It is best to think of it as a substance that makes possible 
 
 the life and activity of the cell rather than as 
 
 a substance that has definite and fixed chemical 
 
 properties. Furthermore, it is important to 
 
 remember that the composition of protoplasm 
 
 varies in the same cell according to many 
 
 factors. Exercise, food, fresh air, alcohol, 
 
 and disease cause changes in the protoplasm. 
 
 Some of these changes are favorable. Can 
 
 you name, from the above, the factors which 
 
 cause unfavorable changes? Physiology is 
 
 the study of the way this protoplasm acts in 
 
 the cells of the body. 
 
 Nucleus. A living cell has two essential 
 parts. One is a small mass or globule* of 
 protoplasm, and the other is a small body 
 within the mass of protoplasm, called the 
 nucleus * (Fig. 2) . There are two other parts 
 of less importance. Within the nucleus there 
 may be a small body, called the nudeolus* 
 and usually the protoplasm has a membrane 
 surrounding it, called the wall. The nucleus 
 is the vital part of the cell. If a cell is 
 divided, that portion containing the nucleus 
 alone survives. After they lose their nucleus, 
 the red cells of the blood live only a few days. 
 
 One-celled animals. The cells of the body, 
 owing to the fact that they have a wall, soft food (as seen 
 contents, and a nucleus, resemble minute one- U Q^ ^ f h ^e 
 celled animals sometimes found in stagnant microscope), 
 water. Figure 3 shows the appearance under 
 the microscope of the amoeba, one of these small animals. 
 The amoeba seems to be hardly more than a minute drop of 
 jelly, yet it lives and does in a simple way many of the things 
 
Healthful Living 
 
 that the human body can do. It moves by pushing out a 
 part of its body ; it takes in food by rolling a process of its 
 body around the food to be eaten ; and after digesting the 
 part it wants, it discards the indigestible portion of the food. 
 If the amoeba is struck or jarred, it reacts by moving its body. 
 It absorbs oxygen * from the air and it gives off carbon dioxide.* 
 When it attains a certain .size, it divides into two parts. It 
 does not divide, however, and produce new individuals 
 until it has reached its full growth.* 
 The origin of cells. For many 
 years it was believed that life origi- 
 nated spontaneously. This viev 
 is called the theory of spontane 
 ous generation. We know now, 
 however, that all cells are derived 
 from cells (Fig. 4) and that the vast 
 number of different cells which com- 
 pose a living body are all derived 
 from two single cells, the ovum* 
 (Fig. 5) and the spermatozoon* 
 The health and strength of these two 
 cells are dependent upon the health, 
 strength, and vigor of the whole 
 body. In this respect, the strength 
 and vigor of the race are dependent 
 upon the strength and vigor of each 
 member of the race. This is an im- 
 portant responsibility because each 
 person, by being strong and vigorous, 
 makes it possible for coming genera- 
 tions to have health and strength. 
 In this way, health is a duty that 
 no one may neglect. 
 The properties of cells. If we say that a stone is hard, 
 that it sinks when thrown into the water, that it will break 
 
 FIG. 4. A cell under- 
 going division. A, cell be- 
 fore division ; B, thread-like 
 formation of the vital parts 
 of the nucleus ; C, equal di- 
 vision of the nuclear thread ; 
 D, separation of the nuclear 
 structure for the new cells 
 and commencing constric- 
 tion of cell body ; E, nuclei 
 beginning return to resting 
 states ; F, complete division 
 of cell body into daughter 
 cells whose nuclei have re- 
 turned to the resting states. 
 
The Cells of the Body 5 
 
 when hit with sufficient force, we are speaking of the proper- 
 ties * that belong to the stone. Cells also have properties 
 
 FIG. 5. Different stages in the development of the frog's egg (-4) to 
 form the body of the frog. In D the egg (ovum) has divided many times, 
 and presently these cells will begin to change into bone, nerve, and muscle 
 cells, and other types of body cells. 
 
 the characteristics which distinguish them from other struc- 
 tures. 
 
 In the first stages of the formation of the body, the cells 
 which later on develop into muscle cells, or nerve cells, or 
 skin cells, look very much alike and have identical properties. 
 They can divide and reproduce themselves (the property of 
 reproduction*) ; they can take up food and build it into tissue * 
 and remove the waste (the property of metabolism *) ; they can 
 receive an impulse and conduct it to all parts of the cell (the 
 property of irritability * and conductivity *) ; they can respond 
 to a stimulus and contract the cell body (the property of 
 contractility *) . 
 
 They also change in their properties. Certain cells be- 
 come unable to contract, but are very proficient in sending 
 nerve impulses ; others cannot secrete digestive juices, but 
 they are able to reproduce the individual. We say, there- 
 fore, that the sex cells develop the property of reproduction, 
 the nerve cells the properties of irritability and conductivity ; 
 the digestive and excretory cells develop the property of me- 
 tabolism, and the muscle cells the property of contractility. 
 
 Tissues formed from cell groups. Cells of one kind 
 group .themselves together to perform a particular function 
 and are called a tissue. We speak of muscle tissue, and we 
 
6 Healthful Living 
 
 understand that there is this grouping of many muscle cells 
 for the purpose of contraction. Therefore, a group of cells 
 of a particular kind to perform a particular function is known 
 as a tissue (Figs. 6, 7, 8). 
 
 Organs formed from tissues. Tissues combine to per- 
 form more effectively a highly complex act. The resulting 
 structure is an organ. Tissues grouped in a definite way to 
 cooperate their tissue functions in some special task are 
 known as an organ. The stomach, for example, is an organ 
 composed of muscle, nerve, and connective tissues, and each 
 tissue cooperates in the digestion of food in the stomach. The 
 muscle contracts the stomach and moves the food at the 
 proper time into the intestine; the nerve tissue tells the 
 muscles when to contract, and the epithelial cells when to 
 secrete digestive juice ; and the connective tissue binds the 
 other tissues together to produce the whole organ. 
 
 Similarity between living organisms and social groups. 
 It has been learned that the body is composed of cells with 
 special properties grouped into tissues ; that the tissues are 
 arranged to form organs. An individual constructed to 
 carry on the activity of life by means of parts or organs 
 which are separate and yet dependent upon each other is 
 called an organism* Man is, therefore, frequently referred 
 to as an organism. The term is sometimes used with refer- 
 en^ce to society. The relation of the parts of the body to the 
 whole body and of the individual man to the organism of 
 society is very important. We have learned that there are 
 organisms composed of only one cell and that such organisms 
 may show all the properties of living matter. As soon as 
 an organism becomes multicellular,* an arrangement is nec- 
 essary for groups of cells to take up certain special tasks. 
 This arrangement and organization permits greater achieve- 
 ment in the group because certain cells are free to accomplish 
 results which would have been impossible in an unicellular * 
 type of organism. 
 
The Cells of the Body 7 
 
 This division of labor among cells may be likened to a 
 similar division of labor that occurs in human society. A 
 city with its million inhabitants is a superior social group 
 for the performing of greater tasks than are possible for the 
 people in a pioneer settlement. In this respect, the organism, 
 man, is superior to the amoeba. Both man and a city are 
 superior as types because they have greater opportunities 
 and can make better use of abilities in acts that enrich the 
 life of the world. The city is more complex, more alive, 
 more sensitive than the pioneer settlement, but in order to 
 maintain this highly specialized state it must be exceedingly 
 watchful against disease * and degeneration.* In this same 
 way, man, a highly specialized organism, superior to the 
 unicellular animals, needs to be careful of the laws of life 
 and health, the observance of which makes such high special- 
 ization * possible. In each case then, in animal life and in 
 human society, specialization produces a superior life, but 
 it also produces the need for intelligent care of the basis of 
 life. The castle needs a better foundation than the kennel. 
 
 One-celled animals and primitive society. The basis of 
 life for the complex organism is the same as that for the 
 simple organism. The amoeba in its self-dependence is like 
 the savage living alone. Modern man with his highly de- 
 veloped body is like the organization of a great city. In 
 each case, however, the simple organism and the complex 
 organism resemble each other by requiring food, air, and 
 water, by needing activity of the proper kind and the re- 
 moval of body waste. In a complex society, it is necessary 
 that all groups of men do their special tasks well. In a 
 similar fashion, man must look for his strength and security 
 to the proper functioning of all his cells, and in no instance 
 may he with impunity sacrifice the removal of waste to the 
 development of the nerve cell. All must be cared for. 
 
 The developed body and modern society. The more com- 
 plex an organism becomes the greater is the necessity for 
 
8 Healthful Living 
 
 cooperation. In human groups there is this important re- 
 lation between men and women and their fellow members in 
 society, which illustrates the cooperation required in the 
 developed body. Members of the human family are de- 
 pendent upon each other. The chemist has to rely upon 
 the integrity of the manufacturer of chemical apparatus ; 
 the farmer is dependent upon the chemist for a complete and 
 accurate analysis of his soil ; the child in school is dependent 
 upon the teacher for guidance and instruction ; and every 
 man must rely upon other men to do their work honestly 
 and efficiently. Therefore, just as man is dependent upon 
 his fellow men, just as eight players on a baseball team are 
 dependent upon how the ninth player plays the game, just 
 as the work of a class is dependent upon the cooperation of 
 the individual members, so in the body, cells in one place 
 are dependent upon the action of other cells forming some 
 other part of the body and doing a different sort of work. 
 The muscle cells cannot act unless the nerve cells do the 
 work of sending nerve impulses ; the nerve cells cannot send 
 and receive impulses unless the heart and lung cells do the 
 work that is expected of them. This interdependence of cells 
 upon other cells and of men upon other men is very important. 
 Similarity between the human body and a city. In com- 
 paring the city with an animal such as man, it will be noted 
 that the construction of the city and the way its work is 
 carried on resemble the body and the activities of its cells. 
 The city proper is composed of buildings that serve definite 
 purposes ; the body is made up of a great number of distinct 
 cells which perform special tasks. The stores on the out- 
 skirts of the city obtain their supplies from the wholesale 
 district by the established channels of trade and commerce ; 
 the body cells receive their nutritive supply through the 
 blood channels which run past the great digestive tract and 
 respiratory tract. The blood with its millions of red blood 
 cells transporting life-giving oxygen, and with its plasma, 
 
The Cells of the Body 9 
 
 carrying life-giving food, resembles a continuous chain of 
 auto trucks transporting the necessities of life to the out- 
 lying population. The waste products are carried by the 
 blood to the kidneys, skin, and lungs organs which serve 
 to remove this waste material. So in a city the " white 
 wings " gather the ashes, rubbish, and garbage and, carrying 
 it to the disposal plant or scows in the river, perform for the 
 city the function of excretion. 
 
 The city is controlled and directed by officers elected by 
 the people. These officers must provide for the life and 
 development * of the people, not only with reference to what 
 they need in the way of food, protection, and recreation, but 
 also with reference to what other cities are doing in pro- 
 viding for man the best opportunities for life. In similar 
 fashion, the body is controlled and directed by the nervous 
 system, which constantly receives messages from all the 
 cells of the body. To .these messages it responds and pro- 
 vides the necessities of life. It also responds to messages 
 from other men. In this way, man and city, both, in co- 
 operation with other groups and led by high ideals, achieve 
 the best development. 
 
 GLOSSARY 
 
 Carbon Dioxide. A gas having the composition of two molecules 
 of oxygen in combination with one of carbon. It is heavy, 
 colorless, and incombustible. It is produced in the decay 
 of animal and vegetable matter and in the bodies of animals 
 during activity. 
 
 Conductivity. Ability to carry heat or electricity. In nerves, 
 it is the ability to transmit stimuli from one part of the body 
 to another. 
 
 Contractility. Power to change the shape, to shorten, in the case 
 of a muscle. In single cells, the shortening in one direction 
 produces an increase in diameter in the opposite direction. 
 
 Degeneration. The change in the chemical constitution of the cells 
 from a complex to a simpler chemical form. 
 
io Healthful Living 
 
 Development. A series of changes by which the body progresses 
 from a lower to a higher type of being. Growth may best 
 be thought of as an increase in substance; development 
 refers to the organization of that substance. 
 
 Disease. The general term for any deviation from health. It 
 may be caused by destruction of essential body cells, or by 
 poisoning so that the cells are unable to function properly. 
 
 Globule. A small spherical structure. 
 
 Growth. The process of increasing in size. It is to be dis- 
 tinguished from development, which refers to organization of 
 the mass. 
 
 Irritability. The responsiveness that living matter shows to 
 more or less rapid changes in external conditions, manifested 
 by motion, change of form, and in other ways. 
 
 Metabolism. The act or process by which on the one hand food 
 is built up into living material, and by which on the other 
 hand the living matter in protoplasm is broken down into 
 simple, waste elements for removal from the body. Some- 
 times the building up of food into protoplasm is called 
 anabolism; the breaking down into simple waste products, 
 katabolism. 
 
 Multicellular. Many-celled. 
 
 Nucleolus. A small, well-defined particle found within the nu- 
 cleus of the cell. It is easily stained with staining fluids, and 
 because it absorbs stain more readily than the nucleus, it is 
 distinguished without difficulty. 
 
 Nucleus. A round or oval body within the protoplasm ; it is 
 surrounded by a delicate membrane. The nucleus is respon- 
 sible for the vital functions of the cell. 
 
 Organism. A body composed of different organs or parts, per- 
 forming functions that are mutually dependent and essential 
 to life. A single cell may be considered an organism although 
 the different parts are not readily distinguished. 
 
 Ovum. A cell produced by the generative organs, the ovaries, 
 of the female. It is capable of producing a new individual. 
 
 Oxygen. In chemical terms, oxygen is represented by the letter 
 O. It is a colorless, tasteless, odorless gas, very abundant 
 in nature. It was first discovered by Priestley in England. 
 It combines with other chemical elements, and all mechanical 
 power obtained from combustion, whether through the medium 
 of steam, electricity, or muscular action, depends upon oxida- 
 tion. 
 
The Cells of the Body n 
 
 Properties. Distinguishing characteristics. Qualities that make 
 the object what it is. 
 
 Protoplasm. The semiliquid, more or less granular substance 
 that forms the principal portion of an animal or vegetable 
 cell. It is present in all organized bodies and so Huxley 
 called it " the physical basis of life." 
 
 Reproduction. The process by which an animal or plant gives 
 rise to another of its own kind and therefore the process by 
 which life is continued from one generation to another. 
 
 Specialization. The setting apart of an organ or part for per- 
 forming a particular function. 
 
 Spermatozoon. The germ-cell of the male which joins with the 
 ovum in reproducing a new individual. These cells are com- 
 posed of protoplasm and illustrate specialization. 
 
 Tissue. An arrangement of cells in a definite manner. The 
 cells are grouped in masses of one kind. 
 
 Unicellular. One-celled. Consisting of a single cell. 
 
CHAPTER II 
 
 TISSUES 
 
 I. Kinds of Tissues. 
 II. Epithelial Tissues. 
 
 Mucous and serous membranes 
 Glands 
 The teeth 
 The skin 
 The hair 
 The nails 
 III. Indications of Good Health. 
 
 Kinds of tissues. In all but the single-cell type of life 
 the body is composed of an arrangement of many cells. 
 These cells, as we have learned, are of different kinds. They 
 have come from a single cell but in developing they have 
 specialized in order to do a certain kind of work. From the 
 cells there has developed a substance which lies outside the 
 cell wall ; it is known as the intercellular substance. 
 
 Now, it is a very important fact that certain tissues arc 
 more highly specialized than others. Such tissues become 
 more highly developed because they have a more important 
 work to do. It is generally understood that nerve tissue 
 is more valuable than the tissue that forms our nails or our 
 hair. Nevertheless, some foolish people take better care of 
 their hands than they do of their nervous system. Physi- 
 ology should teach us what is relatively more important. 
 
 In the construction of the body different types of tissues 
 Are used. By analogy, the body may be likened to a house, 
 where sills, rafters, plates, and studding are used for the 
 
Tissues 
 
 frame. Other material different in shape and form is used 
 to fashion the separate rooms, to provide a covering, and to 
 make the place habitable. So the tissues in the body serve 
 particular purposes. We say, therefore, that the muscle 
 and the nerve tissues serve the body in acting and thinking ; 
 the epithelial and the connective tissues afford protection 
 and support to the muscle and the nerve tissues. Of these 
 four tissues, the epithelial and the connective may be re- 
 garded as elementary, being common to both 
 plants and animals. Muscles and nerve 
 tissues are seen only in animals. The four 
 kinds of tissues, therefore, are epithelial, con- 
 nective, muscular, and nervous. 
 
 Epithelial tissues. Covering the surface, 
 and lining every cavity and tube of the body 
 is a tissue consisting of one or more layers of 
 distinct cells, forming what is called epithelial 
 tissue. It is very simple, consisting merely 
 of cells packed closely together, and united 
 by a very small amount of cement substance 
 (something like the white of egg), which 
 holds the cells together. The cells may be 
 in a single layer or in many layers. .No 
 blood- vessels pass into the epithelial tissue ; 
 the cells derive their nourishment * from the 
 blood exuded into the adjacent tissues. 
 
 The epithelial tissues may be placed, according to their 
 function, in two divisions. One is chiefly protective in 
 character, such as the skin, the lining of the mouth, trachea, 
 and alimentary tract. The other kind of epithelial structure 
 consists of cells that contain highly active protoplasm. These 
 cells are engaged in forming secretions* from food brought to 
 them by the blood. Such are the cells of the salivary glands, 
 which secrete the saliva * ; of the gastric glands, which secrete 
 gastric juice* ; of the pancreas, sweat glands, kidneys,* liver, 
 
 FIG. 6. Two 
 
 gastric glands. 
 Simple tubular 
 glands such as 
 these may be 
 likened to a well ; 
 the cells are like 
 the bricks of the 
 well-curb. 
 
Healthful Living 
 
 FIG. 7. Cells forming a membrane. (Mucous 
 membrane of intestines.) A few cells (dark) that 
 secrete mucus are shown. 
 
 etc. This class of epithelial tissue is of the greatest value in 
 removing waste from the body and in preparing the food 
 for use by the body. 
 
 Mucous and serous membranes.* Epithelial cells, in se- 
 cretory glands, within the body produce powerful digestive 
 
 juices, as in the 
 liver, stomach 
 (Fig. 6), pan- 
 creas ; or they 
 serve to protect 
 passageways and 
 cavities (Fig. 7) 
 with a secretion 
 whose function is 
 chiefly to lubricate the part. All cavities * to which air has 
 access, as the mouth, stomach, and lungs, are lined with one 
 or more layers of closely packed epithelial cells, called 
 mucous membrane (Figs. 7, 8). All cavities from which 
 the air is cut off, as the heart, are called serous cavities, and 
 have a lining of epithelial cells 
 forming what is called a serous 
 membrane. 
 
 These membranes secrete a lu- 
 bricating fluid. The fluid formed 
 by the mucous membrane is called 
 mucus ; that formed by the serous 
 membranes is called serum. The 
 line where the skin and the mucous 
 membrane of the lips join can be 
 plainly seen, as the latter mem- 
 brane is so thin that the color of the blood shows through it. 
 Glands. Glands (Figs. 9-13) are always lined with epi- 
 thelial cells, which form a secretion. These glands vary 
 in shape ; some being tubular, others bag-shaped. The cells 
 of the gland, in their own distinctive way, make use of the 
 
 FIG. 8. Epithelial cells 
 lining the mouth. 
 
Tissues 
 
 
 various chemical substances in the blood, so that one gland 
 
 secretes oil, another perspiration,* another saliva, another 
 
 gastric juice, etc. The kidneys are 
 
 important glands which resemble 
 
 some of the glands of the skin in 
 
 that they secrete injurious substances 
 
 that must be removed from the 
 
 system. Secretion is the name given 
 
 the various fluids formed by glands. FIG 9 A t ical 
 
 If this fluid is waste to be removed, structure of a mucous 
 
 it is Called an excretion.* membrane with two layers 
 
 of epithelial cells, a, 6, 
 Secretion by glands IS not Sim- c , the connective tissue 
 
 plv a process of beneath ' with ^ blood - 
 
 ^ , vessels ; and /, connective 
 
 SOakmg Or Sifting tissue cells. B, the same 
 
 through. The cells with one layer of 
 
 resting on b, the so-called 
 of these glands are basement membrane. 
 
 wonderful little 
 
 chemical laboratories and they produce 
 FIG. 10. A simple the different secretions from the blood in 
 tubular gland with their own way. Moreover, by the aid of 
 
 blood-vessel. The , r 
 
 letters, a, b, c, and e the secretory nerves, they can tor a time 
 refer to the same struc- regulate the amount of secretion regard- 
 
 tures as shown in Fig. , . ,. , , , . -, , 
 
 9. less of the quantity of blood circulating 
 
 around them, although usually the amount 
 of secretion is greatly influenced by the supply of blood 
 in the skin (Chap. XII). Sometimes 
 the skin is hot from the abundance 
 of blood flowing through it, as dur- 
 ing a fever, but it is dry then, as 
 well as hot, because the sweat glands 
 are not active. At times, under the 
 influence of excitement or fear, a 
 person breaks out in a profuse perspi- 
 ration, which is cold, however, for 
 
 there is little blood in the skin. the gland. Namea.&.andc. 
 
i6 
 
 Healthful Living 
 
 FIG. 12. A sac- 
 like gland. 
 
 The teeth. The teeth are developed from the same kind 
 
 of tissue (epiblastic *) that produces mucous membrane, 
 glands, and skin. These struc- 
 tures, like the hair and nails, 
 arise from papillae* in the 
 dermis of the skin. A tooth 
 growing from epithelial-form- 
 ing cells extends down in a 
 
 depression in the jawbone, called a 
 
 socket,* and is held in place largely 
 
 by the tightness with which the 
 
 root, or lower part, fits into the 
 
 socket. The visible part of the 
 
 tooth is called the crown. 
 
 Permanent Teeth. A complete 
 
 set of teeth in adults consists of 
 
 sixteen in each jaw or thirty-two in 
 
 all. They are named according to 
 
 their form and the uses to which FlG , .13- -A racemose or 
 
 branching gland, part only 
 
 they are adapted. There are eight being shown. Name the 
 (Fig. 14) in each quarter of the ^ indicated b ^ & - c - 
 mouth; and if the names of the 
 
 eight in one quarter are learned, you know the names of 
 the thirty-two, since they are designated by the same 
 
 names, in the same 
 order, in each quar- 
 ter of the mouth. 
 Looking then at the 
 teeth in one half of 
 one jaw and naming 
 
 FIG. 14. Teeth from one side of the lower them in order from 
 
 are two incisors, one 
 canine, two bicuspids, and three molars. How many of each 
 kind are found in the whole mouth (Fig. 14) ? 
 
Tissues 17 
 
 The eight teeth in front are for the cutting of the food, and 
 hence are called incisors, or cutters. They have chisel- 
 like edges. Do the edges of the upper and lower teeth 
 usually meet in the mouth, or do they miss each other like 
 the blades of scissors? The incisors are very long in gnaw- 
 ing animals such as rats and squirrels. Next to the two 
 incisors in each quarter of the jaws, comes one canine, so 
 called because the corresponding tooth in the jaws of dogs 
 is well developed. In cats, tigers, dogs, and other flesh- 
 eating animals, it is suited for tearing. It has only one root, 
 but that is a long one. The two upper canines are fanci- 
 fully called the " eye teeth," and the two lower, the " stomach 
 teeth." Next in order behind the canines are the two bi- 
 cuspids, which are grinding teeth. Their crowns are broad. 
 Last of all come the three large grinders, called molars. Are 
 the grinding surfaces of the molars smooth or rough ? Are 
 they like or unlike the surfaces of the bicuspids ? The last 
 molar in each jaw is called the wisdom tooth, because it does 
 not come until the person is supposed to have reached years 
 of discretion. Activity is the law of life, and the wisdom 
 teeth are so far back in the mouth that they are not much 
 used ; therefore, they do not usually remain so long as the 
 others. 
 
 Milk Teeth. Milk teeth are the first teeth to appear. 
 The teeth just described are those of the permanent set. 
 The first or temporary set of teeth also called the milk 
 teeth consists of teeth the same in name and number as 
 those of the permanent set except that the three large molars 
 in each half of the jaw, twelve in all, are lacking; so there 
 are twenty teeth in the temporary set (Fig. 15). The milk 
 teeth come in the first two years of life, and begin in the 
 sixth or seventh year to be pushed out and replaced by the 
 permanent set. They are all gone by the twelfth year. On 
 the other hand, the presence of the milk teeth is important 
 in the development of the jaw. If a milk tooth remains so 
 c 
 
i8 
 
 Healthful Living 
 
 long as to cause the tooth of the second set to grow out of 
 place, the first tooth should be removed. If the milk tooth 
 decays, it should be filled, and if the filling comes out it should 
 be replaced by the dentist ; the milk teeth are an important 
 
 FIG. 15. Diagram of temporary and permanent teeth, showing only 
 the parts outside the gum line. 
 
 stimulant for the proper development of the permanent teeth, 
 the jaws, and the bones of the face. 
 
 Parts of a Tooth. The main part of the body of a tooth 
 is dentine * (Fig. 16) . The dentine of the teeth of elephants 
 and other large animals is the ivory of commerce. It is 
 commonly used to make piano keys, fans, and many novelties. 
 In the central part of the dentine is a space called the pulp * 
 cavity. The soft substance, called the pulp, contains the 
 nerves and blood vessels, which enter at the tip of the root. 
 In the socket, the dentine is covered by cement ; above the 
 socket it is covered by enamel, a substance harder, denser, 
 and more shining than the dentine. 
 
 The enamel wears off of the top of the crown between 
 the twentieth and thirtieth years. Although the dentine 
 
Tissues 
 
 is exposed through the wearing or breaking of the enamel, 
 it will last for years without decaying, but it is more likely 
 to decay than the enamel. We should never run the risk 
 of breaking the enamel by crushing hard candies or cracking 
 nuts. A tooth should never be 
 pulled if it can be saved by being 
 filled ; for pulling a tooth means 
 not only the loss of one tooth, but 
 the end of the usefulness of the tooth 
 opposite to it, and imperfect chew- 
 ing in that part of the mouth. 
 Losing a tooth is equivalent to los- 
 ing a part of life. 
 
 Hygiene of the Teeth. Decay 
 of the teeth is caused (1) by using 
 only soft food which requires no 
 pressure of the teeth while chewing 
 it; (2) by particles of food that 
 lodge between the teeth and become 
 quickly decomposed * in the warm, 
 moist mouth ; (3) by the collection 
 of tartar on the teeth. This is a 
 yellowish deposit that forms on the 
 teeth when they are not kept clean'. 
 (4) Constant nibbling of candy 
 
 causes injury to the teeth through the fermentation of the 
 sugar left in the mouth. 
 
 In cleaning- the teeth, the toothbrush should be rubbed 
 up and down as well as across the teeth. Most tooth powders 
 are made from chalk as a base ; and fine precipitated chalk* 
 is considered perfectly satisfactory for cleansing the teeth. 
 The teeth should be cleansed at least twice a day and always 
 before going to bed at night. The teeth should be examined 
 once a year by a dentist, and the cavities promptly filled. 
 Adenoids* should not be allowed to deform the jaw and so 
 
 FIG. 16. Vertical sec- 
 tion of a bicuspid tooth, 
 magnified. 
 
20 
 
 Healthful Living 
 
 produce crooked teeth (Fig. 17). It may be necessary to 
 have adenoids and tonsils removed. 
 
 FIG. 17. Casts of the upper jaw of two children twelve years old. 
 The left one shows typical narrowing of the arch, overlapping of the teeth, 
 and elevation of the palate due to adenoids. The right one is that of the 
 jaw of a healthy, well-built child. (Drawn from photograph by Dr. Frank 
 
 Mathews.) 
 
 The Department of Health of the City of New York, in an 
 effort to help the children in the schools to have better teeth, 
 has issued the following instructions to parents : 
 
 DEPARTMENT OF HEALTH 
 
 THE CITY OF NEW YORK 
 Instructions to Parents Regarding the Care of the Mouth and Teeth 
 
 The physical examination of school children shows that in 
 many instances the teeth are in a decayed and unhealthy condi- 
 tion. 
 
 Decayed teeth cause an unclean mouth. Toothache and disease 
 of the gums may result. 
 
 Neglect of the first teeth is a frequent cause of decay of the 
 second teeth. 
 
 If a child has decayed teeth, it cannot properly chew its food. 
 Improperly chewed food and unclean mouth cause bad digestion, 
 and consequently poor general health. 
 
 If a child is not in good health, it cannot keep up with its studies 
 
Tissues 21 
 
 in school. It is more likely to contract any contagious disease, 
 and it has not the proper chance to grow into a robust, healthy 
 adult. 
 
 // the child's teeth are decayed, it should be taken to a dentist at once 
 
 The teeth should be brushed after each meal, using a tooth 
 brush and tooth powder. 
 
 The following tooth powder is recommended : 
 
 2 oz. powdered precipitated chalk. 
 
 % oz. powdered castile soap.* 
 
 1 dram powdered orris root.* 
 
 Thoroughly mix. 
 
 This prescription can be filled by any druggist at a cost not to 
 exceed fifteen cents. 
 
 The child should take the tooth brush and powder to the school 
 and receive instructions from the nurse as to their proper use. 
 Issued by Order of the Board of Health 
 
 The skin. We have learned that epithelial cells form 
 mucous and serous membranes, teeth, and secreting glands. 
 They also form the skin covering the body, and from these 
 skin cells there develop the hair and the nails. The thick- 
 ness of the skin is due to the great number of cells composing 
 it. These cells are arranged in a definite manner, in two 
 layers, the dermis and epidermis. 
 
 The outer layer, or epidermis, rests on the inner layer, 
 the dermis (Fig. 18). The dermis is called the true skin. 
 The epidermis is composed of a mass of cells held together 
 by a cement substance. Those near the surface are hard 
 and flattened ; those deeper down, near the dermis, are 
 round and soft. The lowest layers contain a pigment* con- 
 sisting of minute grains of coloring matter. The varying 
 amount of this pigment present causes the difference in hue 
 of the blonde and brunette and the light and dark races. 
 Freckles are due to an increase of pigment in patches of 
 neighboring cells. Some persons lack the pigment entirely ; 
 their hair and skin are white, the eyes pink. They are called 
 albinos. 
 
22 
 
 Healthful Living 
 
 The Dermis. The main part of the skin is the dermis ; 
 it is chiefly a network of fibers. This is the part of the skin 
 of animals that is tanned for leather. Did you ever notice 
 
 the fibrous appear- 
 ance in the leather of 
 a shoe that has be- 
 come much worn ? 
 Which side of leather 
 is smooth, the side 
 covered by epidermis, 
 or the other side? 
 The dermis is con- 
 nected with the body 
 beneath by a loose 
 tissue consisting of 
 fibers interwoven with 
 cells of fat (Fig. 18). 
 This tissue, together 
 with the skin itself, 
 partly conceals the 
 outlines of the mus- 
 cles beneath. Yet 
 artists study the 
 muscles carefully, as 
 their shape shows 
 faintly through the 
 skin and gives a 
 key to the human 
 figure. 
 
 The outer surface of the dermis grows into numerous little 
 projections called papillae. If its covering of epidermis 
 were taken off, the dermis would appear somewhat like 
 coarse velvet because of its unevenness ; for the prominences 
 or papillae appear, in a cross section of the skin, under the 
 microscope, buried beneath the cells of the epidermis, like 
 
 Sweat 
 G/and3 
 
 Nutr/ent Artery 
 
 FiG. 18. Sectional view of the skin, mag- 
 nified. Find : oil (sebaceous) gland, sweat 
 gland, sweat duct, hair bulb. Compare thick- 
 ness of epidermis, dermis, and subcutaneous 
 tissue. 
 
Tissues 
 
 2 3 
 
 a tiny mountain range. As the epidermis fills up the valleys 
 between them, the papillae do not show plainly on the sur- 
 face of the skin. However, on the palm of the hand and 
 fingers, where the papillae are especially numerous, they are 
 
 N. B.-Do not write on this side of the sheet. 
 
 Classification JVb. 
 RIGHT HAND. 
 
 ILD ON THIS LINE I 
 
 "LEFT HAND. 
 
 FIG. 19. The finger prints of the right and left hand, 
 is distinctive for each individual. 
 
 The marking 
 
 crowded into rows, their positions being shown by the parallel 
 ridges seen on the epidermis of the palm. These markings are 
 very distinct on the palm. Moisten the index finger and notice 
 that an imprint of the finger shows when pressure is made on 
 white paper (Fig. 19) . Under what conditions are finger prints 
 of service ? Within the papillae are found the ends of nerves 
 and loops of small blood vessels called capillaries* (Fig. 18). 
 
24 Healthful Living 
 
 Epidermis. The cells of the epidermis which lie next 
 to the dermis are living cells. They are kept alive by 
 nourishment brought by the liquid portion of the blood in 
 the blood vessels of the neighboring papillae. These cells 
 grow and when they have matured they divide and produce 
 new cells. The multiplication of the cells would cause the 
 epidermis to increase greatly in thickness, were not the outer 
 cells constantly worn away by friction. This happens the 
 more easily because the outer cells are dead cells. The new 
 cells forming beneath push them so far away from the dermis, 
 that nourishment from the blood no longer reaches them, 
 and they die. 
 
 By this constant loss and renewal, the body always has a 
 comparatively new outer skin. Even on the scalp, which is 
 partly protected from friction, the flat dry cells are constantly 
 coming off. If there is much oil on the scalp, the cells stick 
 together and form flakes called dandruff. This physiological 
 shedding of the cells of the epidermis is to be aided by bathing 
 the skin and shampooing and brushing the hair. 
 
 Organs of the Skin and Their Functions. Lodged among 
 the fibers of the dermis and supported by them are (1) a fine 
 network of blood vessels ; (2) a fine network of nerves ; 
 (3) several million sweat glands ; (4) a great number of oil 
 glands. Suppose you were to stick a pin into the dermis. 
 The pin would first pass through the epidermis. After 
 entering the dermis there would be two signs that certain 
 structures had been encountered. What are these structures ? 
 What signs would appear? 
 
 The blood vessels in the skin are fine tubes which carry the 
 blood supply to and from the skin. These vessels have 
 muscles in their walls, and when stimulated through the 
 nerves of the skin, the vessels change their size. Warmth 
 causes an increase in size of the vessel and more blood is 
 brought to the skin ; cold causes a decrease in size and the 
 opposite effect is produced. 
 
Tissues 
 
 The nerves of the skin serve two main functions. One 
 function is to control the size of the vessels by responding 
 to changes in temperature ; the other is to make us aware 
 of the character of things we touch. The nerves of the skin 
 of the fingers in this latter function are more sensitive* 
 than those in any other part of the body. 
 
 The sweat glands, or perspiratory glands are little tubes, 
 lined with epithelial cells, which pass through the epi- 
 dermis and down into the dermis. The tube is coiled 
 
 
 FIG. 20. Coiled end of a sweat gland, epidermis not shown, a, the 
 coil ; 6, the duct ; c, network of capillaries. The gland and capillary net- 
 work are shown separated and combined to indicate how completely the 
 organ is supplied with blood. 
 
 into a ball in the true skin, where it is surrounded by a net- 
 work of capillaries (Fig. 20). Its course through the epi- 
 dermis is spiral like the turns of a corkscrew. Its opening 
 on the surface is called a pore. The coiled part is 
 supplied with nerves which stimulate the cells to secrete 
 perspiration. The cells obtain their supply of material 
 from the blood, and this supply is controlled by the 
 
26 Healthful Living 
 
 nerves which regulate the size of the arteries* leading to 
 the skin. 
 
 The sweat glands take up water and various other sub- 
 stances from the blood and pour them out on the surface of 
 the epidermis. The water evaporates, but the salt and 
 other solids in the perspiration are deposited on the skin. 
 Usually the amount of perspiration from each gland is so 
 small that it evaporates as soon as it reaches the surface, and 
 hence does not become visible. On this account it is called 
 insensible perspiration; it becomes sensible perspiration 
 when it is formed rapidly in warm weather or during vigor- 
 ous exercise. It does not evaporate so quickly in a moist 
 atmosphere; and those who live near the seacoast or in 
 rainy regions show more perspiration than those who live 
 in dry regions. The evaporation of this moisture on the 
 skin cools the body. Why is the heat so oppressive on a 
 " muggy " day ? The amount of perspiration averages about 
 one and one half pints a day. Is the skin more active in 
 throwing off impurities in winter, or in summer? 
 
 The oil glands, or sebaceous glands, are small, irregu- 
 larly-shaped cavities which open into the little pits from 
 which the hairs grow (Fig. 18). A few oil glands open 
 directly upon the surface. They are lined with epithelial 
 cells. The cells deposit a kind of oil, which flows out of the 
 mouth of the glands, renders the epidermis flexible and less 
 penetrable by water, and prevents it drying out by evapora- 
 tion and cracking open. It is also the natural " hair oil," 
 for softening the hair and keeping it from becoming brittle. 
 The oil glands of the center of the face are especially large 
 and numerous. When their mouths are stopped by dirt, 
 they become distended with oily material and cause black- 
 heads. Oil glands are absent from the soles and palms. 
 
 Protection of the Skin. Clothing does not give heat 
 to the body but helps to prevent the escape of bodily heat. 
 Linen and cotton absorb moisture readily and allow it to 
 
Tissues 
 
 27 
 
 evaporate rapidly. They thus serve, when worn next to the 
 skin, to keep the body dry; the evaporation, however, if 
 very rapid may chill the body. Woolen absorbs moisture 
 quickly, but parts with it slowly, and, in the case of those 
 who perspire freely, the 
 damp clothing next the 
 skin may conduct away 
 the heat. In this way 
 woolen may seem cool. 
 But dry woolen contains 
 much air in the meshes of 
 the cloth ; and as this is a 
 non-conductor of heat, 
 such clothing is the warm- 
 est of all, silk ranking 
 next. In cold climates 
 woolen should be worn 
 next to the skin, and 
 should not be laid aside 
 until the heat of summer 
 begins. In warm 
 climates, like that 
 of the Gulf States, 
 it should not be 
 worn next to the 
 skin at all, even 
 in winter, except 
 
 ;*T*>^:i~ SS 
 
 ^5sSwfe 
 
 y*y<3sir*r? 
 
 ' , /. i 
 
 nerve 
 
 enafnti 
 e,ssner>s 
 corpusc/e} 
 
 >< * 1 '";:f V t o/- 
 
 FIQ 2L _,_ 0i arrow indicates where the epidermis 
 separates in the formation of a blister. The serum 
 K-.T +V> - A^\\ f the blister exudes from the cells below, which 
 
 Dy tne very deli- are supplied by capillaries, 
 cate, and it is a 
 
 question as to whether woolen does not do more harm than 
 good, even to the delicate, as it relaxes and weakens the 
 skin. If it is worn in such climates, with the warmth of 
 spring it should be changed for less relaxing fabrics. White 
 clothing reflects the heat of the sun ; dark clothing absorbs 
 the sun's heat. Rubber clothing prevents moisture from 
 
28 Healthful Living 
 
 penetrating to the body and also prevents perspiration from 
 escaping. Bed clothing should not be too heavy. On 
 account of the warm air between them, two coverings are 
 warmer than one equal to the two in thickness. The bed 
 clothing should be aired thoroughly every morning. 
 
 When the epidermis is broken so that the true skin is ex- 
 posed, the epithelium* at the edge of the break usually pro- 
 duces new cells to cover and heal the opening. But if new 
 cells do not form, sufficient to bridge the opening, the dermis 
 sprouts through, forming proud flesh, which must be scraped 
 off or cauterized before the epidermis can complete the heal- 
 ing. In the case of a blister, the lowest cells of the epidermis 
 are not removed (Fig. 21), hence the epidermis is readily 
 renewed. Preparations advertised to make new skin over 
 a cut or injury should not be used. Nature will grow the 
 epidermis if the part is kept clean. 
 
 When the epidermis is weak the papillae over a small 
 area sometimes become overgrown, so that they project 
 above the skin, and form a wart. If it is burned away with 
 acid, the epidermis will grow over the place. Why is a wart 
 rough? How does it differ from a mole? Which is more 
 likely to increase in size? Which has more pigment? 
 Which contains hairs? 
 
 Hygiene of the Skin. The scales of the epidermis are 
 gradually passed off, and with the secretions from the oil 
 glands and surface dirt, they tend to form a pellicle* or coat 
 which interferes with the proper functioning of the oil and 
 perspiratory glands. Bathing removes this pellicle and is of 
 great importance in maintaining a healthy skin. The cold 
 bath is intended to stimulate the body; the warm bath is 
 cleansing. The best time to take the cold bath is before 
 breakfast. If this practice is started in the summer, it may be 
 continued through the winter and not be disagreeable even 
 with very cold water. It is best to have a warm room for 
 the bath. Every one may take a cold bath because a sponge 
 
Tissues 29 
 
 and a basin of water are the only necessary articles, although 
 a shower is to be preferred. A warm bath is more suitable 
 on retiring than on rising ; it is also more suitable for a 
 person who is fatigued. A warm bath has a soothing effect 
 on the nervous system. The proper time to bathe is just 
 before a meal or at least three hours after. Sea-bathing is 
 beneficial to the health of the skin and body in general, but 
 its effects are due to the enjoyable exercise and pure out- 
 door air of the seashore. Bathing in ocean or lake should 
 not be prolonged until the bather's lips are blue. 
 
 The complexion is the outward expression of inner health. 
 A good complexion cannot be bought in a box or bottle. 
 An artificial complexion produced with cosmetics and face 
 powder is as barbaric and unnatural as the war-paint of the 
 savage. Do you know a girl who paints and powders her 
 face? Is she a wholesome, healthy appearing girl? A little 
 powder is of value at times on oily skins, but its abuse gives 
 an improper appearance and interferes with the proper 
 action of the skin. 
 
 The face should be washed at least twice daily. Cold 
 water should be used because it improves the circulation, 
 it tones up the elastic fibers, and it prevents chapping and 
 roughening of the skin. Unless the face is very dirty it 
 should be washed without soap. A vigorous washing with 
 cold water or with warm water followed by cold water will 
 remove the dirt in most cases. If the skin is dry a cream 
 may be used to soften it, but it is to be remembered that the 
 best way to get a beautiful complexion is to take proper care 
 of the functions of the body and to indulge in regular exer- 
 cise, preferably out of doors. 
 
 The Skin as an Index of Health. People prefer a clear 
 skin of fine texture to a mottled, pimply, coarse skin. This 
 preference is based partly on the attractiveness of the one 
 and the repulsiveness of the other. It is also sustained by 
 the wholesome desire to appear well and strong, for it is 
 
Healthful Living 
 
 recognized that the skin very delicately and accurately 
 shows the bodily condition. 
 
 In an effort to state clearly from your own observation 
 the value of health, answer the following questions : 
 
 1. Name five blessings in youth or in later life that result from 
 good health. 
 
 2. Name five unfortunate results of bad health. 
 
 3. Name five things that people apparently value more highly 
 than health. 
 
 4. Think of ten grown persons. How many of the ten are in 
 sound health so far as you can tell ? What are the signs ? 
 
 The hair. It has been learned that the papillae in the 
 dermis are composed of epithelial cells arranged in minute 
 projections. A hair is composed of 
 a column of minute epithelial cells 
 which grow from a depression in a 
 papilla. This depression is the hair 
 follicle* or "root." Therefore, a 
 hair grows from a papilla below the 
 epidermis. The only point at which 
 the cells of the hair and, therefore, 
 the hair itself, are living and grow- 
 ing is at the top of the papilla, deep 
 down in the follicle (Fig. 18). From 
 this it is easy to see that the com- 
 mon notion that cutting off the ends 
 of the hair, either by shaving or 
 
 trimming with scissors, causes it to grow faster and stronger, 
 is erroneous. It may stop the splitting of hairs and thus 
 prevent the wearing away of the hair. Of course, when the 
 hair or beard is short its growth is more noticeable. Long- 
 hair seems by its weight to give exercise to minute muscles 
 in the skin and to strengthen the flow of blood, thus adding 
 to the vigor of the hair. The cut end of a hair is nearly 
 round in the straight-haired races, as Indians and Chinese ; 
 
 FIG. 22. A, section of 
 hair ; B, piece of human 
 hair, magnified. 
 
Tissues 31 
 
 it is oval in the wavy-haired white race, and flattened still 
 more in the kinky-haired negro race. 
 
 Hair is very durable (Fig. 22) ; that found on Egyptian 
 mummies has remained unchanged through several thousand 
 years. It is elastic and is said to stretch one third of its 
 length without breaking. Hair absorbs moisture readily 
 and for a time its length is considerably increased thereby. 
 Each hair follicle has fine muscles connected with it. Cold 
 or fear may cause the muscles to contract and the hairs, 
 which are usually in a slanting position, to stand erect. This 
 causes the hair to afford a better protection to the animal 
 from cold or blows. " Goose skin," which occurs if a cold 
 bath is unduly prolonged, is caused in the same way; but 
 the hair on the human skin is so fine that the. goose skin 
 avails little against cold. 
 
 Superfluous hairs sometimes grow on unusual parts of the 
 face. To remove this hair so that it will not grow again, 
 the papillae at the bottom of the follicles must be destroyed. 
 This is no easy matter. Numerous " infallible remedies " 
 are advertised, but the only effective way is by means of 
 electricity, used in an electric needle by a skilled operator. 
 
 Care of the Hair. The two main causes for falling hair 
 are a tight scalp with a poor circulation and the presence of 
 dandruff. The two important things to attend to, there- 
 fore, are massaging the scalp in order to promote the circu- 
 lation, and keeping the scalp clean by daily brushing of the 
 hair and shampooing every two or three weeks. Why does 
 the groom spend so much time in currying and brushing his 
 horse ? 
 
 The nails. Nails are a growth of the epidermis, and, 
 like the epidermis, only the lowest cells near their roots are 
 alive and receive nourishment. The root of the nail is in 
 a kind of groove or fold of the true skin at the bottom of 
 which papillae are very numerous. The nail may be re- 
 garded as a very wide flat hair. The nail grows not only at 
 
Healthful Living 
 
 -Naif 
 
 Epidet 
 
 Uermis 
 
 FIG. 23. Section of nail and parts 
 beneath. 
 
 its root but along its bed, which is of true skin (Fig. 23). 
 Hence, "its thickness increases as it approaches the tip. If 
 the epidermis is pressed back at the root, the nail may not 
 be perfectly nourished, and a white speck or flaw is formed, 
 which travels slowly along with the growth of the nail. It is 
 said that the nail is renewed in three or four months. If 
 you note the date of the appearance of a scar at the base 
 
 of the nail and note when 
 it has traveled to the tip, 
 you can find whether this 
 is true. Find whether or 
 not a nail is transparent, 
 by looking through the tip 
 
 of the nail, held up to the 
 light. The nails stiffen the 
 ends of the fingers and aid 
 in handling small objects. Can you pick up a pin without 
 using the nails ? Corresponding organs in the lower animals 
 are claws and hoofs. 
 
 In manicuring the nails a file should be used. Cutting 
 makes them brittle. Biting the nails is often a sign of nerv- 
 ousness and should be controlled, not only because of the 
 unpleasant habit but also because of the injury to the nails 
 themselves. Proper care of the body involves manicuring 
 the nails and this care should be given. A well-groomed 
 appearance increases one's self-respect and commands the 
 respect of others. 
 
 Indications of good health. One* may be not definitely 
 sick and yet lack the feeling of good health. This is ex- 
 pressed at times as not being up to " par." Health is not 
 only a condition of freedom from disease but also a quality 
 of life and it is to our advantage to keep ourselves at the 
 highest and best level of health attainable. In this 
 connection there are certain indications of health that are 
 valuable : 
 
Tissues 33 
 
 1. Consciousness of feeling well. Allied to this, of course, is 
 the absence of pain. 
 
 2. Enjoyment of activity of muscle and mind. One is not 
 at the highest point of efficiency if activity is not enjoyed. 
 
 3. Sound sleep with a feeling of being rested in the morning. 
 One should be sleepy when tired out, and one is in normal condi- 
 tion in this respect if he can go to bed and sleep. 
 
 4. Normal appetite and normal digestion. The power to 
 enjoy wholesome food, to eat and enjoy a good breakfast. 
 
 5. Power to remove the waste of the body without taking drugs. 
 
 6. Poise and control in the muscular movements of the body. 
 This means the involuntary movement of breathing also, and 
 requires that the individual breathe calmly, deeply, and regularly. 
 
 7. Ability to accomplish the work that lies ahead. This does 
 not mean that all work must be successful, but there should be 
 the feeling that there is achievement. 
 
 8. Throughout all these activities, the happy, cheerful disposi- 
 tion is a sign and indication of good health. This does not mean 
 that one .must go about with a smile or grin on the face, but a 
 habit of meeting difficult tasks without fear or discouragement 
 should be cultivated. 
 
 These eight indications are of value in that they point out 
 the way of health, which is something more than mere ab- 
 sence of disease; it means abundant health of such a kind 
 that one can do more work and also give and receive more 
 happiness and enjoyment in the world. 
 
 APPLIED PHYSIOLOGY 
 
 Exercise I 
 
 1. If a hair is pulled out, what determines whether it will grow 
 again ? 
 
 2. Why is linen used for towels ? 
 
 3. What causes the hair to " stand on end " when a person is 
 frightened or when an animal is cold ? 
 
 4. What color of clothing is best adapted to summer? To 
 winter ? 
 
 5. How may rubber shoes make the feet moist? 
 
 6. State a fact which shows that the skin is a regulator of 
 temperature 
 
34 Healthful Living 
 
 7. Are wrinkles a sign that the skin is too tight or too large 
 and loose for what it covers ? 
 
 8. In what ways may a city and the body of man be compared ? 
 
 9. Describe the division of labor in cells. 
 10. What are signs of health in the body? 
 
 Exercise II 
 
 11. Why does the heat seem more oppressive in moist weather? 
 
 12. Which should usually wear warmer clothing, a farmer or 
 a merchant ? 
 
 13. Which teeth are important for the development of the bones 
 of the jaw and face? 
 
 14. In what respect do patent leather shoes resemble rubber 
 shoes ? 
 
 15. Why is baldness more common among men than among 
 women ? 
 
 16. What are the important principles in the care of the hair ? 
 
 17. Why is a complexion considered beautiful when it is pink 
 and fair ? 
 
 18. What is the best means of improving the circulation in 
 the skin? 
 
 19. Who is more apt to have a sincere nature, a person with 
 a clean face and truthful complexion, or one who paints and 
 powders ? 
 
 20. What are the functions of the skin? 
 
 Exercise III 
 
 21. What are the causes of decay of the teeth? 
 
 22. Of what use is this information? 
 
 23. Did you ever know of a case of loss of health caused by 
 changing the warm clothing of daily wear for the thin or scanty 
 dress of a ball or party ? 
 
 24. Why should we remove an overcoat or cloak when we go 
 into a room ? 
 
 25. Why is cold water better than warm water for the daily 
 bath? 
 
 26. Explain how the wearing away of the outer cells of the 
 epidermis contributes to the cleanliness of the body. 
 
 27. What is the effect of cold water upon the skin ? 
 
Tissues 35 
 
 LABORATORY EXERCISES 
 
 Experiment 1. To study the structure and arrangement of the cell 
 in an orange. 
 
 Material. Navel orange. 
 
 Method and observation. Peel the orange and separate a seg- 
 ment. Gently break open a segment and observe the cells filled 
 with juice. In terms of animal tissues, locate the cell wall, the 
 intercellular spaces, and the protoplasm. 
 Experiment 2. To study cellular structure. 
 
 Material. Onion (sprouting), slide, microscope, toothpick, 
 methylin blue, medicine dropper. 
 
 Method and observation. 
 
 (a) Peel a thin piece of tissue from an onion root and place on 
 a slide. Observe with low and high power and identify cellular 
 structure. 
 
 (6) With a clean toothpick take a scraping of cells from the 
 tip of the tongue or inside of cheek. Place scraping on slide and 
 add one drop of methylin blue. Allow the stain to remain one 
 minute and then remove the excess of stain by gently flushing the 
 slide with water from a medicine dropper. Cover with cover glass 
 and place slide under microscope. Identify cell wall, nucleus and 
 protoplasm. 
 Experiment 3. To study cells and tissues. 
 
 Use prepared slides 1 showing different tissues and exhibit 
 these under the microscope. Let the pupils see the main varieties. 
 
 GLOSSARY 
 
 Adenoids. An enlargement of the connective tissue at the upper 
 
 part of the throat where the throat and nose meet. 
 Artery. One of the tubes that convey blood from the heart to 
 
 the cells and lungs of the body. 
 Capillary. A fine, slender blood tube with a hairlike bore. 
 
 Capillaries are the smallest tubes for conveying blood. The 
 
 arteries terminate in capillaries. 
 Castile soap. A white hard soap made with olive oil. In making 
 
 hard soap the alkali used is soda ; if potash is used the product 
 
 is soft soap. 
 
 1 Permanent preparations of cells and tissues may be obtained from 
 Bausch and Lomb Optical Company, Rochester, New York. 
 
36 Healthful Living 
 
 Cavity. A hollow space within the body. The term cavity is 
 used if this space is either actual or potential. 
 
 Decompose. A separation into the chemical elements that make 
 it up. Used to describe decay and disintegration. 
 
 Dentine. The hard dense substance which forms the major 
 part of the tooth. 
 
 Epiblastic. The outermost layer in the developing embryo. It 
 forms the skin, the hair, the teeth, and the nails. 
 
 Epithelium. The tissues in which the cells are arranged to cover 
 free surfaces and to form the active structural element of the 
 glands that secrete. The arrangement of the epithelium is 
 very orderly; epithelium of the mouth can readily be dis- 
 tinguished from the epithelium of the skin, stomach, liver, etc. 
 
 Excretion. The discarded waste from the body. This waste 
 matter is thrown off by the cells and in doing so illustrates the 
 katabolic aspect of metabolism. Excretion is not to be con- 
 fused with secretion, because, although both are produced by 
 the cells of the body, the product of the former contributes 
 to remove waste, and the product of the latter is useful in 
 activities of the body. 
 
 Follicle. A minute cavity, sac, or tube. 
 
 Gastric juice. A thin acid fluid secreted by the glands of the 
 stomach. These glands are composed of epithelium and 
 produce hydrochloric acid and also pepsin and rennin. These 
 substances form the chemical essentials in the juice and are 
 responsible for its action. 
 
 Kidneys. Two organs situated in the back part of the abdomen. 
 The cells are mainly of epithelium and secrete from the blood 
 as it passes through the kidneys the waste that forms the 
 excretion known as the urine. 
 
 Membrane. A thin sheetlike structure composed of epithelium 
 cells and serving to line a cavity, tube, or follicle. 
 
 Nourishment. That which sustains the life and promotes the 
 growth of the individual. 
 
 Orris root. The fragrant, violet-scented root obtained from 
 several species of Iris, a plant with sword-shaped leaves and 
 known in cultivation as fleur-de-lis. 
 
 Papilla. A small nipple-like process. 
 
 Pellicle. A thin film. 
 
 Perspiration. The product of the secretion activities of the sweat 
 glands in the skin. This exhalation is an excretion. 
 
 Pigment. Any substance that gives color to animal or vegetable 
 
Tissues 37 
 
 tissues as exhibited in the skin, the hair, the eye, and the 
 leaves and flowers of plants. 
 
 Precipitated chalk. A heavy, fine powder. It is obtained by pre- 
 cipitating calcium carbonate. It is much used in tooth 
 powders. 
 
 Pulp. The soft tissue composed of blood vessels and nerves and 
 found within the cavity of a tooth. 
 
 Saliva. A tasteless, odorless, slightly viscid, alkaline secretion 
 of the salivary glands of the mouth. 
 
 Secretion. A substance separated from the blood by the cells 
 developed for that purpose. This substance plays some useful 
 part in the body. It is to be distinguished from the term 
 excretion. 
 
 Sensitive. A quality of being easily affected by outside opera- 
 tions or influences. 
 
 Serous membrane. A delicate tissue composed of flattened cells 
 that line the large cavities of the body. These cells secrete 
 a fluid called the serous fluid. It is similar to the serum of 
 blood. 
 
 Socket. A cavity or opening especially adapted to receive some 
 correspondingly shaped piece. 
 
 Vein. A muscular and tubular vessel that conveys blood to the 
 heart. It is distinguished from an artery by having less 
 muscle and elastic tissue in its wall and by carrying blood to 
 the heart ; the artery carries blood from the heart. 
 
CHAPTER III 
 TISSUES (Continued) 
 
 I. Connective Tissues. 
 
 White fibrous tissue 
 Yellow elastic tissue 
 Adipose tissue 
 Cartilaginous tissue 
 Osseous tissue 
 II. Muscular Tissues. 
 
 Oxidation and muscular action 
 
 Oxidation and burning 
 
 Oxidation in the body and in a machine 
 
 Points of similarity between the human body and a steam 
 
 engine 
 Points of difference between the human body and a 
 
 steam engine 
 
 Muscular contraction and chemical change 
 Alcohol and muscular efficiency 
 
 III. Nervous Tissues. 
 
 Nerve structure 
 
 How nerves and muscles work together 
 
 IV. Building Good Tissues. 
 
 The effects of alcohol 
 The effects of drugs 
 Stimulation vs. construction 
 
 Connective tissues. Connective tissue serves the body 
 by affording support to its several parts. The fibrous tissue, 
 which binds the cells together and supports the various 
 organs, is also called connective tissue, but it is distinguished 
 from the connective tissues in general by the name " white 
 fibrous connective tissue." In some of this tissue there are 
 
 38 
 
Tissues 
 
 39 
 
 yellow elastic fibers, hence the name " yellow elastic con- 
 nective tissue " is used. The tissues that are to be grouped 
 under the connective tissue head- 
 ing are : 
 
 1. White fibrous tissue (Fig. 24). 
 
 2. Yellow elastic tissue (Fig. 24). 
 
 3. Adipose (fatty) tissue (Fig. 25). c 
 
 4. Cartilaginous tissue (Fig. 26). 
 
 5. Osseous (bony) tissue. 
 
 White fibrous tissue. White 
 fibrous connective tissue consists 
 of cells that have very small 
 nuclei and cell bodies that are 
 prolonged into fibrous strands 
 (Fig. 24). These fibers may be 
 considered as a development of 
 the cell (Fig. 24, c). They are 
 
 . & . ' . / FIG. 24. Connective tissue 
 
 not elastic. IhlS tissue lorms taken from beneath the skin, 
 the ligaments * Structures that yellow elastic fibers ; b, white 
 
 fibers; c, cell which forms the 
 
 hold the ends of bones together, kind of fiber shown in b. 
 making a joint. 
 
 Yellow elastic tissue. Yellow elastic connective tissue 
 is found scattered among the white fibers (Fig. 24). It is 
 relatively large in amount in the walls of the blood vessels, 
 and in the firm part of the ear. 
 
 Adipose tissue. This soft tissue furnishes cushions for 
 delicate organs like the eye, forms a layer under the skin, 
 thus rounding out the form and storing up food for the use 
 of nerve, muscle, and other cells. The fat is first deposited 
 in the form of minute globules in the white connective tissue 
 cells ; these globules gradually increase in size. Fatty 
 tissue is, therefore, nothing more than fat deposited in the 
 cell body of white connective tissue (Fig. 25). What is 
 lard ? Tallow ? Suet ? In what tissue do these substances 
 lie? 
 
4 o 
 
 Healthful Living 
 
 Cartilaginous tissue. Some parts of the body require 
 tissue having something of the rigidity of bones, yet capable 
 
 White Fibrous 
 'Connective Tissue 
 
 Protop/asm 
 
 FIG. 25. Fatty tissue. Five fat cells, held together by bundles of 
 connective tissue. 
 
 of bending under pressure. This purpose is fulfilled by the 
 elastic tissue called cartilage. A piece obtained fresh from an 
 animal is seen to be covered by a thin fibrous membrane, 
 which is reddish because it contains blood vessels. When 
 this membrane is stripped off, the cartilage shows no sign of 
 redness, that is, it contains no blood vessels. Under the 
 microscope, cartilage is seen to be composed of cells, often 
 arranged in pairs (Fig. 26), which suggests the fact that they 
 have been formed by the division of one cell. The substance 
 between the cells is the product of the cells, has been de- 
 
Tissues 41 
 
 posited by them, and is called the intercellular substance or 
 matrix.* 
 
 Cartilage may be readily felt in the nose at the tip, and in 
 the ears. The cartilage of the ear contains an abundance 
 of elastic fibers. The 
 cartilage between the . ^ ofTwo 
 divisions of the ver- 
 tebral column con- 
 tains both yellow 
 elastic and white 
 fibrous cells. It is, "*'"* 
 therefore, in nature, 
 
 7 ,. , , i FIG. 26. Cartilage. A thin section, 
 
 elastic and tough. highly magnified . 
 
 Osseous tissue. 
 
 Just as white fibrous tissue supports and holds in place 
 the delicate cells and fibers of the organs, so bone and 
 cartilage support the complete organs and hold them in 
 their places in relation to one another. Cartilage and 
 bone are closely related as to location, function, and de- 
 velopment. For example, the flat bones, in infancy, form- 
 ing the roof and sides of the skull, are soft and flexible, being 
 composed of cartilage, except for a small patch of bone in the 
 middle of each. As growth proceeds, the bones touch and 
 interlock, replacing the cartilage. If a bone is broken, the 
 new part, as it forms, is first cartilaginous and afterward it 
 is replaced by true bone. Growth in length of the bones 
 takes place in the cartilage at the ends of the bones. A 
 person ceases to grow in height at about the age of twenty- 
 five on account of the ossification of the cartilage. 
 
 There are machined for increasing one's height. They 
 work by stretching the spine. Many persons could become 
 taller by standing and walking in an erect posture. After 
 the ossification of the cartilage in bone, however, increased 
 height can only be secured by making the body more erect, 
 either by machines or by exercise. 
 
42 Healthful Living 
 
 All bones are covered by a thick fibrous tissue called 
 periosteum.* This contains the blood vessels which pass 
 into the bone to supply nourishment and also bone cells 
 which by development increase the circumference of the 
 bone. 
 
 Muscular tissues. The cells constituting the body were 
 likened to a human community or city. Such a comparison 
 helps us to realize how complex is an animal body, and how 
 wonderful are the processes of life. But the relation be- 
 tween the cells is much closer than that between the in- 
 dividuals of a community. There is a marked difference, 
 however. The human being can move as a whole, can 
 change place in space, and can act with the harmonious 
 assistance of the organs of the body. The energy * stored in 
 the body enables it to do these things, and the two tissues that 
 chiefly expend the energy and give us the ability to do thinge, 
 to act, are nervous tissues and muscular tissue. In me- 
 chanical terms, therefore, the body may be called a neuro- 
 muscular mechanism.* 
 
 Oxidation* and muscular action. This energy in muscular 
 action arises from a kind of combustion* or chemical reaction, 
 and resembles, in its source, the energy of the steam engine. 
 That something besides wood or coal is necessary to a fire 
 can be shown by shutting off entirely the draught of the 
 stove. Fire and all other forms of combustion depend upon 
 a process called oxidation. This consists in the uniting of 
 oxygen, the active element of the air, with carbon,* hydro- 
 gen,* and other elements in wood, coal, etc. Bread, meat, 
 and other foods contain these energy elements also. That 
 there is carbon in sugar can be easily proved by charring 
 sugar upon the stove, the charcoal thus produced being a 
 form of carbon. Complex organic * food compounds contain- 
 ing these elements are taken into the body through the diges- 
 tive organs and broken up into smaller units which may be 
 stored in the body cells ready for union with oxygen when 
 
Tissues 43 
 
 action is needed. The oxygen enters the body through the 
 lungs and is carried to the tissues by the red blood cells 
 of the blood. Oxygen is not stored in the body but is taken 
 in in response to the needs of the body for oxygen. 
 
 Oxidation and burning. The body resembles a locomotive 
 in having warmth and motion as a result of the union of 
 fuel and oxygen ; but it differs from the locomotive, since 
 the intelligent engineer is an integral part of it, and since the 
 oxidation in the body is in the presence of moisture, and so 
 gradual that it is not a true fire accompanied by light. More- 
 over the body can repair itself as it wears out, and the engine 
 cannot. The energy stored in the body is used more economi- 
 cally than any steam engine can use fuel. 
 
 Oxidation in the body and in a machine. There are points 
 of similarity and points of difference between the body and 
 the machine. Too often the differences are not noted. The 
 human body is very complex, and the effect of any particular 
 process is so profound that great care must be exercised to 
 avoid stating too positively what any effect will be. There 
 are people who are willing to state what the effect of a certain 
 exercise on the body will be, and they talk about educational 
 exercise and hygienic exercise. In most instances they are 
 unfamiliar with the real meaning of education and hygiene, 
 and they do not appreciate how very difficult it is to predi- 
 cate the effect of any particular exercise. That the body 
 resembles a machine there can be no doubt, but it is quite as 
 important to remember that there are very important 
 differences. 
 
 Points of similarity between the human body and a steam engine. 
 
 1. Both require fuel. 
 
 2. Both transform energy from rough masses. The energy 
 in the wood and coal is potential * and in the steam engine it is 
 changed into kinetic * energy in the form of heat. The energy in 
 meat and potatoes and other foods is potential, and by digestive 
 processes it is changed into kinetic energy. 
 
44 Healthful Living 
 
 3. Both produce waste products and both must have this waste 
 removed. It is just as important to keep the human body free 
 from its waste as it is to keep the ashes out of the furnace box. 
 Many people take better care of the furnace in the home than they 
 do of the furnace in their own body. This is largely because of 
 ignorance and not because of lack of interest. 
 
 4. Both are of complicated mechanism. 
 
 5. Both need repair. The engine cannot repair itself, but the 
 body in many particulars can repair injuries. It is important 
 to remember that the body cannot repair all injuries without 
 the assistance of man. An inflamed appendix,* a broken bone, 
 cancer, and many other instances of injury need the trained hand 
 and intelligence of the surgeon. There are people who attempt 
 to repair the body by taking " patent medicine," and yet they 
 will send for a mechanic to repair the' broken pump or the black- 
 smith to repair the broken wheel of the wagon. These people 
 foolishly attempt to tell what is wrong, and to treat a mechanism 
 that is very complicated ; on the other hand, they would not think 
 of such procedure in repairing a simple mechanism like a pump, 
 wagon, or automobile. 
 
 6. Both need rest. Great industrial plants often have two 
 sets of power engines so that they can rest one set on alternate 
 weeks. Men are saying to-day that they can do twelve months 
 work in ten months, but they cannot do it in twelve. Rest is 
 needed. 
 
 7. Both need exercise, activity. This similarity is very im- 
 portant. In each case the right kind of activity is essential for 
 the most efficient action. 
 
 8. Both, need intelligent care. We need to take as good and as 
 intelligent care of our bodies as the engineer takes of the steam or 
 gasoline or electric engine. 
 
 Points of difference between the human body and a steam engine. 
 
 1. A human body requires a greater variety of fuel. The steam 
 engine will burn coal and will do its best work on that particular 
 kind of supply. The human body will not do its best work on 
 meat or vegetables or nuts alone. 
 
 2. A human body is never entirely inactive. Even at night 
 when asleep, the human body is working, carrying on the processes 
 which keep the body alive. 
 
 3. A human body has the power of self-development. On the 
 physical side it starts with a single cell and grows to maturity. 
 Under intelligent direction, this growth may be directed to produce 
 
Tissues 45 
 
 a very fine type of being. This power of self-development make^ 
 the human body very much more interesting than the steam en- 
 gine. 
 
 Muscular contraction and chemical change. How does 
 the oxidation of food produce motion? We learn that the 
 amoeba and other one-celled animals can change their shapes. 
 Many of the cells of the body have lost this power, but the 
 muscle cells retain it. Figures 79, 80, 81 show various types 
 of muscle cells. They differ in the shape of the cells and to 
 some extent in the structure of the cell, but they are all alike 
 in that they get broader and shorter when they contract. 
 The food that is most easily burned in the muscle is sugar. 
 Sugar is stored in the muscle in the form of glycogen,* and 
 when a nerve impulse comes to the muscle it causes the 
 sugar to undergo a chemical change. This chemical change 
 in the muscle produces heat (see Laboratory Experiment, 
 page 30) and the heat causes such change in the muscle cells 
 that the cells become shorter and broader. This change 
 is called the muscular contraction. If sugar is deficient in 
 the muscle, it is possible for the cells to burn fat * and 
 protein.* The waste from this combustion causes the 
 fatigue* that is experienced after muscle work, and this 
 waste may be likened to the ashes or clinkers left in the 
 furnace after the coal has burned. 
 
 The duration of a muscular contraction varies in different 
 animals. The following table shows the duration of a simple 
 muscular contraction : 
 
 Insect 0.003 second 
 
 Rabbit 0.070 second 
 
 Frog 0.100 second 
 
 Terrapin . 1.000 second 
 
 The height of a muscular contraction depends upon the 
 strength of the nerve impulse and whether the muscle is 
 fresh or fatigued. In other words it depends upon- how hard 
 one tries and upon how much work has been done. The 
 
46 Healthful Living 
 
 strength of the contraction, however, is greater after some 
 work has been done. For this reason, athletes always warm 
 up before trying for a record or running a race or playing a 
 game. It is greater if one has had plenty of sleep and rest 
 at the proper interval, before the activity. Figure 27 shows 
 how fatigue occurs in the muscle of the finger. Using an 
 
 FIG. 27. Tracing of muscular contraction showing a decrease in 
 muscular power (fatigue). 
 
 ergograph,* each contraction of the finger is recorded on 
 smoked paper. The increase and decrease in muscular 
 efficiency is to be noted. 
 
 Alcohol and muscular efficiency. People have had the 
 erroneous idea that alcohol * helps the individual to do work. 
 This belief arose because of the drug effect of the alcohol 
 
 ! 
 
 { 
 I 
 
 Alcohol and Muscle Work 
 
 Mountain- Climbing 
 1 ^(Abstinent Days. ^%%%^j Atcohot Days* 
 
 Expenditure of Energy \vas /5# Greater on Alcohol Days. 
 
 
 
 K^^^^^^^ 
 
 Work Done(foot-pounds per second) Averaged 16. 4% 1ess.cn Alcohol Days. 
 
 I . J 
 
 fcZZZZ^^ 
 
 Time Required to Climb the Mountain 21. 7?? Longer on Alcohol Days. 
 
 i _ -i 
 
 K/^^^^x^^^ 
 
 y/A 
 
 Crubrr. "T/>e A/c oho/ Question " Va/ V2ff No ? /9I2 
 
 
 , 1912, by Scientific Temperance Federation, Boston 
 FIG. 28. Alcohol decreases the ability of man to do muscular work. 
 
Tissues 47 
 
 upon the brain.* It has been shown that from 8 to 10 per 
 cent less work is done when alcohol is taken, even in such 
 small amounts as that present in a pint of beer. Professor 
 Durig, a mountain climber, experimented on Mt. Bilkencrat 
 in the Alps with alcohol to determine the effect upon muscu- 
 lar efficiency. On the days when he took alcohol amounting 
 to 2 or 2-J glasses of beer, " his watch showed that it took 
 21.7 per cent longer to reach the top of the mountain than 
 on the days when he took no alcohol " (Fig. 28). 
 
 It has been shown that alcohol impairs the efficiency of 
 athletes in all contests. A test was made at a marathon 
 
 A 62-Mile Walking Match 
 
 
 Comparison of Abstainers and Non-Abstainers 
 
 
 Match held at Kiel, Germany, 1908 
 
 
 f- 1 Abstainers. V2Z222ZA Non-Abstainers. 
 
 29/5 Percentage of Each Class Entered 
 
 71 % 
 
 1 VZ%%2%2^^ 
 
 lZ%% 
 
 60% Percentage of the JO Prizes Won 
 
 40% 
 
 60% First 25 to Reach Goal 
 
 40% 
 
 27# Last 26 to Reach Goal 
 
 73 * 
 
 1 ^^^^^^^^^^^^^^^^^$^$$$$$$$$$$$^^x^^^$^^^$^ : 
 
 %%$ 
 
 6% Failed to Reach Goal 
 
 94% 
 
 Akttaingra ~on /,t, fnj, 3rd, 4th, 8tf> and fripbcey. Drinkers -ron Stfi, 6th, 7tft and '/&//> places. 
 
 , 1910, by Scientific Temperance Federation, Boston 
 
 FIG. 29. Abstainers are more effective in athletics. Achievement in 
 k all fields of endeavor is greater without the use of alcohol. 
 
 race in Germany with reference to the ability of those who 
 were drinkers and those who were not. The first four men 
 to cross the line after covering a distance of sixty-two miles 
 were abstainers. More than half of the drinkers fell by the 
 way and only two of the abstainers (Fig. 29). In baseball 
 the same test has resulted in managers insisting upon ab- 
 stinence. Connie Mack, manager of the famous " Athletics " 
 in the years when they twice won the championship in both 
 leagues, said, " Baseball men are not now of the drinking 
 
4 8 
 
 Healthful Living 
 
 FIG. 30. The general arrangement of the nervous system (viewed from 
 behind) . Showing the brain, the spinal cord, and the chief nerves that branch 
 from it. 
 
Tissues 
 
 49 
 
 class. The fact is that a big-league player has to be in trim 
 day in and day out or he is sent to the minors. It is the 
 survival of the fittest." He who would excel in the world 
 must leave alcoholic drink alone. 
 
 Nervous tissues. Knowing, as you do, how micro- 
 scopic the cells are in size, what would you think if you were 
 told that there are cells in the body that have parts which 
 extend several feet in length ! There are cells with branches 
 which reach, for instance, from the spinal cord to the toes 
 (Fig. 30). A mass of nerve tissue called the brain occupies 
 almost all of the skull, and the lower part of this nerve tissue 
 forms the spinal cord,* or spinal marrow. Nerve tissue forms 
 also the glistening white cords, called nerves, going from the 
 brain and spinal cord to all parts of the body (Fig. 30). 
 Have you seen a hog's brain or the brain of an ox ? However 
 complicated nerve 
 tissue may seem 
 to be, it is found 
 to consist of nerve 
 cells and their 
 branches, called 
 nerve fibers. 
 Some cells, are ar- 
 ranged in a dis- 
 tinct mass called 
 a ganglion (Fig. 
 37). 
 
 Nerve structure. 
 A nerve consists 
 of a great number 
 of cell-branches or 
 nerve-fibers, just 
 as a number of 
 telephone wires 
 are sometimes 
 E 
 
 4 
 
 FIG. 31. Nerve cells from different animals. 
 A, frog ; B, lizard ; C, rat ; D, man (after Ramon y 
 Cajal). 
 
Sheofh of 
 connective tissue 
 
 50 Healthful Living 
 
 bound together in a cable. Nerve cells grow, become 
 active and die, like other cells, and like other cells they 
 consist of protoplasm with a nucleus and nucleolus. A 
 number of processes branch off from them, some cells 
 giving off only one or two, others many (Fig. 31). One of 
 these processes, larger, longer than the others, forms the 
 nerve fiber or axone. The axis, or central part of the fiber, 
 is a continuation of the jelly like protoplasm of the cell; 
 this core is the essential part of the fiber. The axis is sur- 
 rounded in most fibers by a sheath of fatty material (Fig. 32) . 
 
 This is for nourish- 
 ment and protec- 
 
 tlOD Oi tll6 
 ^ ^ j g 
 
 FIG. 32. Scheme showing structure of nerve o-ivpa fn 
 
 ~, TT j -j. i i j.i i j.- e g,i V Co \j\J 
 
 fibers. How does it resemble the insulation of a . . . 
 
 copper wire used in electric wiring? its characteristic 
 
 ivory-white ap- 
 pearance. The whole is strengthened by being inclosed in 
 a thin, delicate sheath of connective tissue. Some of the 
 nerves go to the muscles, and passing between the bundles 
 of fibers, soon divide into branches, for we have seen that 
 the nerves are bundles of separate fibers. They subdivide in 
 the muscles till they ultimately send a single nerve fiber to 
 each individual muscle fiber. 
 
 How nerves and muscles work together. Suppose you put 
 your hand on a hot stovepipe or poker; it is immediately 
 jerked away. How does this wonderful thing happen ? The 
 heat of the iron causes a disturbance in a nerve fiber ending 
 just under the skin of the finger. This disturbance travels 
 rapidly along the axis, or core, of the nerve, and is called an 
 impulse.* It is not a visible change, but some influence that 
 travels from particle to particle. It resembles electricity 
 somewhat, but some physiologists think it is like a wave of 
 chemical change, running along the nerve faster than a rail- 
 way train can run. It reaches a nerve cell in the spinal cord. 
 
Tissues 
 
 The disturbance there causes the cell to send out impulses 
 along its other branches or fibers. 
 
 Some impulses (Fig. 33) are sent down the arm again to 
 its muscles, causing them to contract, and the arm is jerked 
 away, as we say, by reflex 
 action, or action without 
 will on our part. Other 
 impulses go at the same 
 time to the brain, and we 
 become conscious of what 
 has happened. The nerves 
 which carry impulses to 
 the nerve cells (afferent) 
 are called sensory nerves, 
 or nerves of feeling, arid 
 those which carry impulses 
 from the cells to the mus- 
 cles (efferent) are called 
 motor nerves, or nerves 
 of motion. Nerve fibers 
 transmit impulses, but do 
 not originate them. An 
 impulse in a nerve can be 
 excited by a pinch, a 
 
 J . . FIG. 33. Reflex arc (after Kolliker). 
 
 prick, electricity, a drop The sensory impulse comes from the skin 
 
 Of acid, a hot wire, a COld ? d is directed out to the muscles over 
 
 7 the motor neurons and to the brain by 
 
 Object, Or a thought. Re- the sensory brain paths. 
 
 flex action always occurs 
 
 on account of some influence from the outer world but 
 
 voluntary action comes from activity in the brain. 
 
 Suppose you step out of a warm house into a cold wind. 
 The face immediately blanches or turns white. Let us see 
 how this can be accounted for. There are muscle fibers in 
 the walls of the blood vessels. The cold air excites impulses 
 in the sensory nerves of the face, which travel to the enlarge- 
 
 Sensory 
 /Afferent J ncuran 
 
 from skfn 
 
52 Healthful Living 
 
 ment at the top of the spinal cord just at the base of the 
 brain, called the medulla oblongata (Plate VI). Here the 
 impulse reaches a nerve center which sends it along another 
 set of nerves that go to the muscle fibers in the walls of the 
 blood vessels, causing them to contract, and the face turns 
 white. Thus we see how closely related are these two tissues. 
 
 If we consider that the nerves reach almost everywhere in 
 the body, and that the muscles of the body weigh nearly as 
 much as all other tissues together, we realize how important 
 these tissues are. Let us count up some of the activities in 
 which the muscles are necessary : swallowing, digesting 
 food, breathing, blushing, writing, walking, talking, looking, 
 tasting, chewing, frowning, smiling, laughing, circulation 
 of the blood. There are only a few things, such as hearing, 
 smelling, and feeling, that can sometimes be accomplished 
 without muscles. In their functioning, muscle and nerve 
 cannot be separated. Body reacts on mind ; mind controls 
 the body. 
 
 Building good tissues. As you have learned, all of the 
 tissues are built, maintained, and repaired by living cells. 
 Life and health depend upon the proper and continuous 
 activity of these cells, and anything that aids in this activity 
 strengthens the body and prolongs life; anything that in- 
 jures them or interferes with their activity, impairs the 
 health and shortens life. Growth and repair of tissue are 
 prompted by sunshine, by fresh air, by drinking plenty of 
 pure water, by good food, by active and happy occupation. 
 Weakness and injury of cell and tissue result from depriving 
 the body of these conditions. When these essential condi- 
 tions are absent, the first step in the restoration of health 
 is to restore these conditions, and adapt the daily life to 
 them. 
 
 Injury to tissues shortens the life of the individual. With 
 the knowledge of the injurious effect of alcohol upon the 
 tissues of the body, life insurance companies are refusing 
 
Tissues 53 
 
 insurance to those who are drinkers. Intelligent persons 
 would not sell ten to fifteen years of their life for a portion 
 of alcohol ; statistics show that abstainers live longer. 
 
 The effects of alcohol. Arthur Hunter, of the New York 
 Life Insurance Company, in a report (May 1916) of the De- 
 partment of Health of New York City, shows that the death 
 rate among abstainers is from 10 to 30 per cent lower than 
 among non-abstainers. This report agrees with the British 
 statistics, which also show that alcohol has an unfavorable 
 effect on longevity and that total abstinence increases 
 longevity. The Actuary of the Mutual Life Insurance 
 Company, after an experience of fifteen years, came to the 
 following conclusion : 
 
 " The difference between those who drink beer and those who 
 drink water is unmistakable, while the loss on beer drinkers has 
 been almost the same as among wine and spirit drinkers." 
 
 The effect of drugs. The physician uses drugs in illness 
 to produce certain effects in the body. He can change the 
 rate of the heart, the force of the blood pressure. He can 
 stimulate or quiet the nervous system. He can increase the 
 activity of the sweat glands, cause changes in the intestines, 
 and relax the muscles. But all the effects are accomplished 
 because of some condition existing in a sick body. The 
 giving of medicine must be preceded by a diagnosis of the 
 illness. 
 
 There are some people who are so ignorant of the human 
 body that they are willing to treat themselves and even their 
 friends with virulent * drugs and patent medicines. These 
 persons frequently recommend a drug or endorse a headache 
 powder because it relieved a certain friend, but they fail to 
 realize that every case of illness varies in a marked way, and 
 that the same symptoms * may be present for different dis- 
 eases. 
 
 Some people use drugs because they have formed a habit. 
 
54 Healthful Living 
 
 Drug habits are very injurious because the dose must con- 
 stantly be increased to have the desired effect, and in time 
 the person becomes dependent on it. Morphin, cocain, 
 heroin, headache powders, bitters, and tonics are preparations 
 that are injurious when used carelessly. They are only to 
 be used on prescription by a physician. 
 
 Stimulation vs. construction. The body does not usually 
 need stimulation from alcohol or drugs. The stimulating 
 effects of exercise, wholesome food, fresh air, good com- 
 panions are far more valuable. Alcohol must not be thought 
 of as a stimulant, because it does not construct the body 
 but it destroys. This is one reason why a person who has 
 been used to alcoholic drinks recovers less rapidly from an 
 accident or surgical operation than one who uses none. 
 Sick benefit societies in England and Australia have shown 
 in records that members in the abstaining societies have 
 about half as much sickness as those in the non-abstaining 
 societies. 
 
 In general, it may be stated that care of the body with 
 reference to hygienic living is the best kind of advice to give 
 to people who are continually ailing. Sickness that re- 
 quires a physician is sometimes unavoidable, and in such a 
 case care should be taken to call a good physician, and his 
 directions should be implicitly followed. Self-drugging by 
 the public is considered by some the most fruitful cause of 
 disease in the United States. " Mind cures " and kindred 
 ideas often do more by rescuing victims from poisonous drugs 
 than through their calming effect upon the mind. 
 
 APPLIED PHYSIOLOGY 
 Exercise I 
 
 1. The arteries contain more of the yellow fibers of connective 
 tissue than the veins. Which have the more elastic walls ? 
 
 2. Does fat accumulate in the body within the cells or outside 
 them? 
 
Tissues 55 
 
 3. How can one " add a cubit to his stature " after the age of 
 twenty-five ? 
 
 4. What arguments can you present that may show that al- 
 cohol causes a loss in efficiency to the user? 
 
 5. Does the body take up oxygen? If it is desired to increase 
 the process of oxidation in the body, how can this be accomplished? 
 
 6. In what respect does the body differ from a machine ? 
 
 7. Which animal can contract its muscles the more quickly, 
 a bee or a frog ? 
 
 8. Why should there be " warming up " exercise in the gym- 
 nasium before the main part of the gymnastic lesson ? 
 
 9. What part of the nerve cell is the nerve fiber ? 
 
 10. What is meant by the statement that body reacts upon 
 mind and mind controls body? 
 
 LABORATORY EXERCISES 
 
 Experiment 1. To study a one-celled organism with reference to 
 its 
 
 (a) structure 
 
 (6) reaction to stimuli 
 
 (c) properties 
 
 Material. Hay infusion, 1 pipette, glass slides, cover glasses, 
 microscope, alcohol, and medicine dropper. 
 
 Method. With the pipette draw a few drops of the scum which 
 collects on the hay infusion. This scum usually contains a great 
 number of single cell animals, called paramcecia.* Place a drop 
 of this material on a slide, cover with a cover glass, and examine 
 the specimen under low power of the microscope. 
 
 Observation. 
 
 1. What is the structure of the organisms seen? Is there a 
 definite shape? 
 
 2. Do they move? Do they move with a definite end for- 
 ward? Do they move in any definite direction? 
 
 3. Add a drop or two of alcohol at the side of the cover glass. 
 What happens to the movement of the organism ? 
 
 1 Instructions for making hay infusion. Obtain, from the side of a river 
 or pond, some grasses that have grown on the water's edge. These dry 
 grasses will have on their stems organisms of the single cell type. Place 
 these grasses in a glass jar with water and set the jar in the window of the 
 class room. In two or three days organisms can easily be obtained. 
 
56 Healthful Living 
 
 4. Place a heated needle at one side of the cover glass. Does 
 this produce movement in any particular direction ? 
 
 5. Are there paramoecia around an air bubble? What do they 
 get from that? Is an air bubble necessary for the obtaining of 
 oxygen by this organism? 
 
 6. Are there any paramoecia undergoing division? Reproduc- 
 tion in this organism occurs when it is mature and follows definite 
 laws of division. Draw paramoecia showing structure, reaction to 
 stimuli, and properties. 
 
 Experiment 2. To demonstrate chemical and electrical action 
 with reference to muscular and nervous activity. 
 
 Material. Test tube, pieces of zinc, sulphuric acid, zinc 
 strip, copper strip, current key, electric bell or galvanometer. 
 
 Method and Observation. 
 
 (a) Into a test tube place several pieces of zinc, add some water 
 until the zinc is covered. Feel the test tube and notice any change. 
 Pour in sulphuric acid. Again feel the tube and note the change. 
 The action resulting is chemical in nature and heat is produced. 
 The energy formed here in this chemical action expresses itself as 
 heat. The chemical action in muscle expresses itself as heat and 
 the two actions are similar. 
 
 (6) Make a voltaic cell by placing zinc and copper strips in 
 a twenty per cent solution of sulphuric acid. Connect wires with 
 the end of each strip and fasten the two wires by means of a key to 
 an electric bell or galvanometer. When the key is closed the bell 
 will ring or the needle will move. The energy generated here 
 produces heat, as can be determined by feeling the voltaic cell, but 
 the characteristic effect is the production of an electric current. 
 The chemical action in the nerve cell produces a nerve impulse 
 which is similar to an electric current. 
 
 GLOSSARY 
 
 Alcohol. A volatile, inflammable, colorless liquid of a penetrating 
 odor and burning taste. The chemical formula is (CVHrOH). 
 It is derived principally from sugars and sugar-giving sub- 
 stances such as corn, potatoes, and grapes. Dr. Frederick 
 Peterson classifies it as a poison in the following words, " Al- 
 cohol is a poison. It is claimed by some that alcohol is a 
 food. If so it is a poisoned food. Alcohol is one of the most 
 common causes of insanity, epilepsy, paralysis, diseases of the 
 
Tissues 57 
 
 liver and stomach, dropsy, and tuberculosis." Collier's Weekly, 
 Nov. 30, 1907. 
 
 Appendix. Vermiform appendix is a wormlike organ situated 
 at the junction of the small and large intestine, on the right 
 side of the abdomen. It is the seat of the disease called by 
 the name appendicitis. 
 
 Axone. Sometimes spelled axon, and known as the axis cylinder 
 of the nerve cell. It is the long process that runs from the 
 cell body and joins the processes of the nerve cell with which 
 it connects. 
 
 Brain. The organ of the mind. It is an enlarged portion of the 
 nervous system, located in the skull. It is the organ of con- 
 sciousness, of thought, and of voluntary action. It receives 
 and sends impulses and regulates and controls the functions 
 necessary to life. 
 
 Carbon. An element found in all organic substances. It is 
 present in all foods and usually found in chemical combina- 
 tion with hydrogen and oxygen. 
 
 Combustion. The action or process of burning. The fire in the 
 stove illustrates combustion. In the human body combus- 
 tion is much slower and the continuous combination of chemi- 
 cal substances that produces energy for work is similar to the 
 combustion in the steam engine that produces energy in the 
 form of steam. 
 
 Energy. The quality by reason of which anything is able to act. 
 It represents force. In physics it is the capacity for per- 
 forming mechanical work. There are different forms of energy 
 and one form may be changed into another. No energy is 
 ever lost. 
 
 Ergograph. An instrument for recording work done by the 
 muscles. Mosso, an Italian physiologist, invented the first 
 ergograph. The word comes from ergon, meaning work, and 
 graphos, writing. 
 
 Fat. One of the food elements. 
 
 Fatigue. A condition of diminished ability to do work. The 
 amount of fatigue varies under different conditions. Fatigue 
 of muscle can be measured by the ergograph. 
 
 Glycogen. A complex compound of sugar. 
 
 Hydrogen. A colorless, odorless, tasteless gas represented in 
 chemistry by the letter (H). It is very abundant in nature, 
 occurring in combination with oxygen to form water (H 2 O) 
 and with carbon (C) to form many organic compounds. 
 
58 Healthful Living 
 
 Impulse. Represents the change set up in nerve fibers by 
 means of stimuli coming either from the endings of the nerve 
 in the cells of the body or from the brain or spinal cord. The 
 impulse is a force that travels along the nerve. What its 
 nature is has not been definitely determined, but it is thought 
 to be something like an electric current. 
 
 Kinetic energy. The energy of action. It belongs to every 
 body in motion and is to be distinguished from potential 
 energy. 
 
 Ligament. A band of firm, compact, fibrous tissue that closely 
 binds related parts together. It is most often found binding 
 the ends of two bones together to form a joint. 
 
 Matrix. The formative cells from which a structure grows. 
 
 Mechanism. The structure by means of which action is secured. 
 The neuro-muscular mechanism refers to the arrangement 
 between the nerves and muscles by means of which certain 
 types of action are secured. 
 
 Organic. Relates to organism and pertains to animal and vege- 
 table life. Also used to designate compounds. An organic 
 compound contains carbon and is distinguished from inorganic 
 compounds which contain metals in their composition. Some 
 organic compounds may contain metal, as for example, haemo- 
 globin, which contains iron. 
 
 Oxidation. The process of uniting of some chemical substance 
 with oxygen. All combustion in the body is an example of 
 oxidation and the ability of oxygen to unite with chemical 
 compounds and cause combustion with the production of 
 energy is oxidation. 
 
 Paramoecium. A small animalcule with an elongated, ciliated 
 body. The mouth is in a pit on the under surface of the body. 
 
 Periosteum. The fibro-vascular membrane that covers and 
 nourishes bone. In this membrane runs the blood vessels 
 which carry nourishment to the bone. 
 
 Potential energy. The energy that is in the substance or mechan- 
 ism but not as yet in action. It represents the energy that is 
 available for action. The energy in food is potential but 
 when the food undergoes oxidation and combustion results, 
 the energy becomes kinetic. 
 
 Protein. One of the food elements. 
 
 Spinal cord. That part of the nervous system which lies within 
 the canal formed by the openings in the bodies of the verte- 
 brae. Into this structure come the nerves from all parts of 
 
Tissues 59 
 
 the body ; at the base of the skull it joins with the brain. The 
 brain and spinal cord are called the cerebro-spinal nervous 
 system. 
 
 Symptom. A sign or indication that serves to point out the exist- 
 ence of something else. Pains in the body are symptoms of 
 a condition of abnormality in the body. 
 
 Virulent. Having the characteristic of strength or poison. A 
 virulent infection is one that is severe and dangerous because 
 the poison from the disease is so strong. 
 
CHAPTER IV 
 ORGANS FORMED FROM TISSUES 
 
 I. The Different Systems in the Body. 
 
 II. Organs of the Muscular System. 
 
 III. Organs of the Skeletal System. 
 
 IV. Organs of the Digestive System. 
 V. Organs of the Respiratory System. 
 
 VI. Organs of the Circulatory System. 
 
 VII. Organs of the Nervous System. 
 
 VIII. Organs of the Excretory System. 
 
 IX. Organs of the Reproductive system. 
 
 The different systems in the body. We have learned 
 how the different types of body cells were grouped in tis- 
 sues to form organs. This grouping serves the purpose 
 of bringing together the cells of one kind for a specific 
 task and is similar to the collective work of men and 
 women in an industry. In the body we find muscle 
 cells arranged in large masses for the purpose of contrac- 
 tion ; in a similar way in human society we see the crew 
 of a railroad train working together to accomplish some 
 result. 
 
 But the organization of the body is more wonderful, even, 
 than indicated above. Organs composed of cells of the 
 same or different variety are coordinated into systems that 
 carry out important life processes. A railroad system is an 
 organization of men and women for the purpose of carrying- 
 on transportation. It includes in addition to its executive 
 and administrative officers, trackmen, clerks, telegraphers, 
 
 60 
 
Organs Formed from Tissues 61 
 
 trainmen, repair men. In similar fashion the digestive 
 system, which is concerned with the preparation of food in 
 the body for the use of the body includes in its working 
 organization teeth, salivary glands, stomach, liver, gall 
 bladder, pancreas, intestine, and colon. Not all of the 
 bodily systems have so many different organs cooperating. 
 The muscular system is composed entirely of muscles ; the 
 nervous system comprises brain, spinal cord, and nerves. 
 But whether the bodily systems are composed of the same 
 kind of organs or of many different organs, they are all alike 
 in that the organs cooperate in the system to accomplish a 
 specific result. We recognize in the body eight systems. 
 They are the muscular, the skeletal, the digestive, the 
 respiratory, the circulatory, the nervous, the excretory, the 
 reproductive. 
 
 Organs of the muscular system. The organs of the 
 muscular system are the muscles attached to the skeleton 
 (Figs. 90, 91). These muscles are concerned chiefly in per- 
 forming movements necessary in work and play. We have 
 in this system of muscles an arrangement, so coordinated 
 that movement of the entire body or of parts of the body 
 may be produced readily and efficiently. We shall learn 
 later of some of the separate muscles in this system, but it 
 is sufficient at this time to classify them in the following 
 groups : Muscles of the head and neck, back, chest, ab- 
 domen,* arms, and legs. 
 
 There are other muscles in the body, especially in the 
 walls of blood vessels and in the walls of hollow organs as 
 the stomach and intestine, but the muscles so situated are 
 concerned in the work of other systems and are not to be 
 classified in the muscular system. 
 
 Organs of the skeletal system. The skeletal system 
 (Fig. 43) comprises the bones of the skull, vertebral column, 
 thorax, shoulder girdle, pelvis, arms, and legs. These bones 
 are assembled in a definite order and are held together by 
 
62 
 
 Healthful Living 
 
 ligaments. The bones vary in shape, size, and function, 
 but they. are all concerned in forming a framework for the 
 structure of the body. 
 
 Organs of the digestive system (Plate III). The organs 
 of the digestive system are arranged so that the food taken 
 
 Salivary G/ands 
 Trachea 
 
 GaJl_ 
 B/adder 
 
 Liver 
 
 Duodenum' 
 
 Sa/jyary 
 ~~G/and 
 
 -Esophagus 
 
 Stomach 
 
 -Pancreas 
 
 Vermiform_ 
 Appendfx 
 
 FIG. 34. The digestive system. 
 
Organs Formed from Tissues 
 
 into the mouth must pass along a certain tract and receive 
 the action of the secretions of the organs along the way. 
 Study the diagram in Figure 34 and name the organs. From 
 this study it will be seen that the digestive system is made 
 up of many different organs and in this respect it is unlike 
 the muscular or skeletal systems. But it is similar in that 
 it is an organization of organs for the accomplishment of a 
 specific function. The 
 
 function in this system f | 
 
 is digestion. The organs 
 are teeth, tongue, sali- 
 vary glands, esophagus,* 
 stomach,* liver,* gall 
 bladder,* pancreas,* 
 small intestine, large 
 intestine. After the 
 usable parts have been 
 taken from the food, the 
 remainder or waste is 
 removed from the body. 
 This waste should be 
 removed daily and reg- 
 ularly or the health will 
 be impaired. 
 
 Organs of the respira- 
 tory system. In the 
 case of the amreba and 
 paramcecium, which have 
 only one cell, it is pos- 
 sible for oxygon and 
 
 carbon dioxide to pass directly through the cell membrane. 
 In higher forms, where so many cells are situated below the 
 surface, a means must be provided for getting oxygen to 
 the cells and removing the carbon dioxide. This is accom- 
 plished by the respiratory system. The organs of this 
 
 FIG. 35. Diagram of respiratory 
 mechanism in lung showing how the 
 blood comes in contact with an air sac 
 and thus receives oxygen and gives up 
 carbon dioxide (modified after Adami and 
 Nichols) . 
 
64 Healthful Living 
 
 system are nose, larynx,* trachea,* lungs, and the muscles 
 of respiration, the diaphragm* and intercostals.* This 
 system provides for getting air into and out of the lungs 
 but it is dependent upon the circulatory system for convey- 
 ing the oxygen of the air from the lungs to the cells of the 
 body (Fig. 35). Study the structures in Plate III and tell 
 what they do. 
 
 Organs of the circulatory system. The simplest circula- 
 tory system would be one in which there is a tube that con- 
 tracts and, by the aid of a valve, forces on the fluid within 
 the tube. The water supply sj^stem of a city is a means of 
 water circulation in which the pumps at the station, the 
 water mains traversing all sections of the city, and the 
 running water are the essential parts. The essential organs 
 of the circulatory system of the body are the heart, blood 
 vessels, and blood. In the city water system there are 
 engineers who run the machinery that pumps the water; 
 in the body there are nerves and chemical substances that 
 increase or decrease the rate and force of the heart's beat. 
 These controlling agencies are very important but they do 
 not constitute a part of this system. They illustrate the 
 harmonious action between different systems and one of 
 the ways in which the nervous system coordinates and 
 controls all. Name the parts in Plates III and VIII and 
 trace the blood from the left side of the heart until it reaches 
 the right leg. Trace it from the stomach through the liver 
 and back to the heart. 
 
 Organs of the nervous system (Plates VI and VII). 
 The simplest nervous system is one in which a stimu- 
 lus is carried along a nerve to a nerve cell and the response 
 follows (Fig. 36). If the central cell or mass be joined 
 to other masses, it is possible for a stimulus to come in 
 from one part and go out at another at a different level 
 of the spinal cord (Fig. 37). Suppose that the first neu- 
 ral mass enlarges and takes control over all the other 
 
Organs Formed from Tissues 
 
 masses and directs their activities. In this arrangement 
 we have an illustration from comparative anatomy * of k the 
 
 Nerve Center 
 
 Muscle Skin 
 
 FIG. 36. Diagram of simple type of nervous system. Stimulus coming 
 from the skin is sent by the center * to the muscle. 
 
 evolution* of the nervous system from a simple type to a 
 complex type as seen in man. The nervous system has 
 
 _,.' ' " " " N X I/eod yetny/fon 
 / \^ en/dryes to form 
 
 ! /' \ \ fhp 
 
 FIG. 37. Diagram of a simple type of nervous system. A stimulus 
 coming in at A from the skin of the leg may travel to B in order to get 
 action by the muscles of the arm to relieve the cause of the stimulus. 
 
 evolved to such an extent that in man it is composed of 
 the brain, spinal cord, cranial nerves,* spinal nerves,* 
 
66 
 
 Healthful Living 
 
 Pyramid 
 Cortex 
 
 Medulla 
 
 FIG. 38. Section* of the kidney. 
 
 ganglia,* and pe- 
 ripheral nerves. 
 The brain is the 
 highly specialized 
 center which con- 
 trols and directs 
 (Fig. 37). The 
 rest of the struc- 
 tures exist for the 
 purpose of carry- 
 ing out the will of 
 the brain. Cer- 
 tain acts go on, 
 however, without 
 the brain control- 
 ling them. Such 
 are automatic and reflex. They represent functions that 
 were carried on before the brain developed. They did not 
 need the brain then; 
 they do not need it 
 now. Such acts are 
 breathing and digest- 
 ing food. 
 
 Organs of the excre- 
 tory system (Plate V). 
 As a result of chem- 
 ical changes in the 
 body, there are waste* 
 substances which must 
 be removed. These, 
 
 together with the ex- FIG. 39. Waste from the cells going into 
 
 cess of water in the blood stream. 
 
 blood, are eliminated 
 
 by the chief organs of the excretory system, the kidneys 
 
 (Fig. 38). This system is very important in the mainte- 
 
 Body 
 Co// 
 
 Body 
 
 JJody 
 Ce//. 
 
 'y ff/ood Stream 
 
Organs Formed from Tissues 
 
 67 
 
 nance of body health, and 
 the efficiency with which 
 it works determines very 
 largely the health of the 
 whole body. 
 
 Plate V shows these 
 organs in their position 
 in the body. The large 
 arteries, branching off 
 from the main blood 
 channel, carry the blood 
 to the kidneys, and the 
 veins carry it away after 
 the waste has been re- 
 moved. If the kidneys, 
 through disease or other 
 injury, become unable to 
 remove this waste, the 
 health of the body is 
 impaired. Figs. 39-42 
 show the removal of 
 waste from the cellular 
 spaces and the subse- 
 quent elimination by 
 skin, lungs, and kidneys. 
 
 The problem of keep- 
 ing these organs 
 strong and well is a 
 complex one. All 
 the factors that cause 
 injury to the kidney 
 cells are not known ; 
 but through study, 
 experiment and 
 close observation of 
 
 <> Sweat G/ancf 
 
 Duct 
 
 eat G/and 
 
 FIG- 40. Sweat gland of skin removing 
 waste from the blood. 
 
 FIG. 41. Waste from the blood 
 eliminated by the lung. 
 
 FIG. 42. The elimination of waste by the 
 kidney. 
 
68 Healthful Living 
 
 people's habits of living, some important directions for pre- 
 serving the efficiency of the kidneys have been formulated. 
 
 It is generally agreed by physicians and hygienists that 
 the habit of drinking plenty of pure water is valuable. 
 For an adult, six to seven glasses a day are recommended '. 
 In a day's schedule, the drinking of water could be arranged 
 in this way : one glass on rising, one at breakfast, one in the 
 course of the morning, one at lunch, one in the middle of the 
 afternoon, one at dinner, and one before retiring. 
 
 In addition, attention is to be given to the prevention of 
 excessive work for the kidneys by reducing the amount of 
 waste that these organs will have to eliminate. It will 
 be learned later that the waste from animal food is largely 
 removed by the kidneys. The restriction in meat eating 
 would seem, therefore, to be another valuable method of 
 protecting these organs. 
 
 The skin is, in part, an organ of excretion and so assists 
 the kidneys. Keeping the skin healthy by frequent bathing 
 and by wearing proper clothing is an important part of 
 keeping the kidneys efficient. Chilling of the body, getting 
 the feet wet, and sudden losses in body heat from various 
 other causes, may be injurious to the kidneys. 
 
 Finally, it should be noted that the health of the excretory 
 system cannot be maintained by patent medicines of the 
 Kidney Remedy type. There are innumerable " cures " 
 and " remedies " advertised in newspapers and magazines 
 for the treatment of kidney disease. They are worthless, 
 fraudulent, and exceedingly expensive. The restoration 
 to health of these injured organs is usually a problem of 
 adjustment of life, and the plan and program for that 
 should be in the care of a skilled physician. 
 
 The reproductive system. Simple one-celled animals, 
 such as the amceba, reproduce by dividing into two parts. 
 The entire body divides and two new individuals result from 
 the one. In the higher mammals nature has formed a 
 
CHARTS OF THE HUMAN BODY 
 
 SHOWING 
 
 DIFFERENT SECTIONS OF THE TRUNK AND HEAD 
 
 AND A SCHEMATIC REPRESENTATION OF 
 
 THE CIRCULATION 
 
EXPLANATION OF PLATE I 
 
 Plate I shows the skeletal muscles on the ventral (front) part of 
 the trunk. These muscles lie beneath the skin and are attached 
 to the bones of the skeleton. The blood vessels and nerves which 
 supply the muscles come from within the body and send their 
 branches into the fibers of the muscles, giving nourishment and 
 stimulation, and controlling elimination. The muscles of the trunk 
 are more important than the muscles of the arm from the standpoint 
 of health, because if the trunk muscles are not well developed, the 
 heart, lungs, digestive organs, and nervous system will not be 
 vigorous. 
 
PLATE I 
 
 mm. 
 
.OBL/OUUS; 
 
 ABDOMNAUS 
 INTERNUS-" 
 
EXPLANATION OF PLATE II 
 
 This Plate presents the rear view of the front wall of the body. It 
 shows the ribs which lie beneath the muscles of the chest illustrated in 
 Plate I and the inner layer of tissue that makes up the structure 
 of the abdominal wall. The organs shown in Plate III lie against 
 the ribs and abdominal wall pictured here. 
 
EXPLANATION OF PLATE III 
 
 This Plate shows the organs of the trunk as they appear after 
 removing that part of the body indicated in Plates I and II. The 
 diaphragm runs transversely across the body and separates the 
 organs of the chest (heart and lungs) from the organs of the ab- 
 domen (stomach, liver, intestines, etc.)- The diaphragm is a muscle 
 and when it contracts it moves downward and helps to bring air 
 into the lungs. Notice the situation of the liver, and stomach. 
 Increased action of the diaphragm following exercise massages these 
 organs and improves their action. Breathing exercises alone are 
 not as valuable as those that cause the respirations to increase in 
 response to the needs of the body. 
 
PLATE III 
 
EXPLANATION OF PLATE IV 
 
 This view shows the rear of those structures indicated in Plate III. 
 Part of the lungs have been removed to show the way in which the 
 blood vessels from the heart enter the lungs, and to show the tubes 
 (bronchi) which carry air in and out of the lungs. In the abdominal 
 part there are two organs that were not shown in Plate III. One is 
 the pancreas, that lies behind the stomach, and the other is the gall 
 bladder, that lies on the under surface of the liver. Notice the large 
 blood vessels going to the intestines. If the muscular wall shown 
 in Plate I is not held in place and well contracted these blood vessels 
 will be stretched and will be less able to carry blood to the organs 
 of the abdomen. It is important, therefore, always to stand erect 
 so that the organs of the abdomen will receive the full supply of 
 blood which they need. 
 
PLATE IV 
 
 
EXPLANATION OF PLATE V 
 
 This Plate presents the front view of the back wall of the trunk 
 with all the organs of the chest and abdomen removed except the 
 kidneys and bladder. This view shows the esophagus, which empties 
 into the stomach ; the large blood vessels going to and from the 
 heart. The kidneys are seen receiving blood from the renal artery 
 and sending blood away in the renal vein. The kidneys take the 
 impurities from the blood and remove the excess of water. The 
 excretion is carried in tubes, marked ureter, to the bladder. All 
 the organs are of importance in maintaining the health and strength 
 of the body, and the excretory system is as important as if not more 
 important than the others. 
 
PLATE V 
 
EXPLANATION OF PLATE VI 
 
 This Plate shows structures inside the skull and face. It is a 
 composite picture, being made up of several different sections. It 
 shows the spinal cord with its connections with the cerebrum (brain) ; 
 the eye and optic nerve ; and nerves going from the brain to the 
 teeth, the nose, and the muscles of the neck. It is to be noticed that 
 the brain and nerves are well protected, the brain being covered by 
 the bony skull and the nerves gaining protection from the bones of 
 the face and soft parts. The bones protecting the spinal cord have 
 been cut away in order to show this structure. 
 
PLATE VI 
 
PLATE VII 
 
 ^-ai-CKL^ 
 
EXPLANATION OF PLATE VII 
 
 This view of the head is that which would be presented by 
 looking at the surface of the sagittal section through the head. 
 The opening from the mouth into the esophagus and the path- 
 way from the nose to the lungs are shown. The spinal cord 
 entering the base of the brain is clearly indicated and some of the 
 internal structures of the brain are represented. The corpus callo- 
 sum is composed of fibers connecting the two sides of the brain. 
 The cerebellum is shown cut across ; the pons lies in front of it. 
 In the medulla are situated the vital centers of life the respiratory, 
 cardiac, and vaso-motor centers. 
 
 EXPLANATION OF PLATE VIII 
 
 [OVER] 
 
 This Plate represents the circulation of the blood. The blood 
 flowing from the left side of the heart is represented in the arteries 
 by a circular marking ; that coming to the right side of the heart 
 and from there to the lungs, in the veins by a straight line. This 
 representation of veins and arteries indicates a difference in structure ; 
 it also suggests one very important fact in the circulation the 
 blood which the heart sends out to the cells of the body is not the 
 same in composition as that which returns to the heart. The chief 
 difference is a waste product of oxidation, carbon dioxide. Trace 
 the blood from the left side of the heart to the head, hands, and 
 feet by the arteries; trace the blood from the right side of the 
 heart to the lungs ; and trace the blood from the head, hands, and 
 feet by the veins to the heart. 
 
PLATE VIII 
 
Organs Formed from Tissues 69 
 
 complex system of special organs to care for this important 
 work Of reproducing the species. Nature's laws here as 
 elsewhere are helpful when understood. Ignorance of these 
 laws results, frequently, in disease, in loss of health and 
 happiness. Parents or the family physician are the logical 
 persons to instruct children in these laws. It should be 
 remembered that the proper care and functioning of this 
 system determines not only the health and happiness of the 
 individual, but also the health and prosperity of the race. 
 
 APPLIED ANATOMY 
 LABORATORY EXERCISES 
 
 1. To demonstrate the digestive organs. 
 
 Obtain from the body of a cat or rabbit the stomach and in- 
 testines. Tie off the two ends. Show the relations between 
 stomach and intestines. Indicate the mesentery and show how 
 the blood vessels coming to the intestines run in the mesentery 
 supporting the tube. 
 
 2. To demonstrate the organs of respiration and circulation. 
 From the same source as in (1) obtain the lungs and heart. 
 
 Place the specimen in water. Do the lungs float ? Show the rela- 
 tion between lungs and heart. 
 
 3. To demonstrate organs of the nervous system. 
 
 Obtain from the butcher a fresh calf brain and also a section of 
 the spinal cord of the hog or calf. Show how the spinal nerves come 
 off from the cord and indicate the root of origin of the cranial nerves. 
 
 4. To demonstrate organs of the muscular system. 
 
 Obtain from the butcher the fore leg of a can 3 . Dissect out the 
 tendinous attachment of the muscles and at the joint indicate the 
 difference between the tendon and the ligament. 
 
 5. To demonstrate the organs of the excretory system. 
 Obtain from the butcher the kidneys from a calf and indicate 
 
 for the class the arterial and venous blood supply. By a diagram 
 show how the kidney removes waste from the body and emphasize 
 the importance of water in the diet. 
 
 GLOSSARY 
 
 Abdomen. The cavity lying between the diaphragm and pelvis 
 and holding the viscera. The viscera is the plural term for 
 
yo Healthful Living 
 
 viscus. Viscus refers to the organs in the abdomen, such as 
 the intestines and stomach. 
 
 Center. Used here in connection with the nervous system, i.e., 
 nerve center. A group of nerve cells arranged in a circum- 
 scribed mass for the purpose of carrying on a particular func- 
 tion or coordination. 
 
 Cerebrum. The upper and foremost part of the brain. It con- 
 sists of two symmetrical halves, called hemispheres. In man 
 and the higher animals the cerebrum is the chief bulk of the 
 brain. It is supposed to be the seat of thought and will. 
 
 Cerebellum. A part of the brain lying below and behind the 
 cerebrum. It is much smaller than the cerebrum and is con- 
 cerned with equilibrium and allied functions. 
 
 Comparative anatomy. The study of the structure of different 
 animals and man with reference to similarities and differences 
 in structure and development of organs in different species. 
 
 Corpus callosum. A great band of nerve fibers that runs trans- 
 versely across the brain, connecting the two hemispheres. As 
 compared with other parts of the brain, this band is very hard 
 and it receives its name from being a " hard body." 
 
 Cranial nerves. The nerves that come off from the brain. There 
 are twelve pairs and comprise such nerves as the optic (to the 
 eyes), the auditory (to the ears), the facial (to the face), and 
 the vagus (to the heart). 
 
 Diaphragm. A muscle situated between the cavity of the chest 
 and the abdomen. It is the chief muscle pf, respiration. 
 When it contracts it descends and causes air to rush into the 
 lungs ; when it relaxes it rises and forces the air out. 
 
 Esophagus. A tube composed of muscle and membrane, about 
 ten inches long. It serves to carry food and drink from the 
 mouth to the stomach. It is sometimes called the gullet. 
 
 Evolution. A term to denote the development of the complex 
 individual from the single cell and to explain the way in which 
 all development has occurred and the conditions modifying 
 such development. 
 
 Gall bladder. A muscular bag that lies on the under surface of 
 the liver and holds the bile secreted by that organ. 
 
 Ganglion. A group of nerve cells lying outside the spinal cord. 
 
 Intercostal. One of a group of muscles attached between the ribs 
 and concerned in respiration. 
 
 Larynx. The upper part of the air tube. It contains the vocal 
 cords. 
 
Organs Formed from Tissues 71 
 
 Liver. A large gland composed mainly of epithelium, situated 
 in the upper part of the abdomen on the right side. It se- 
 cretes a liquid called bile ; it stores sugar in the form of gly- 
 cogen ; and it removes certain waste substances that come to 
 it in the blood. 
 
 Medulla oblongata. The extreme upper part of the spinal cord, 
 forming the connecting structure between the cord and the 
 brain. It is conelike, and about one inch long. It contains 
 important nerve centers such as the respiratory center, the 
 cardiac center, the vaso-motor center, etc. 
 
 Pancreas. An organ of digestion concerned in the metabolism of 
 fat, sugar, and protein. 
 
 Pons. Usually called the Pons Varolii after the anatomist of 
 Bologna, Constanza Varoli. It is a part which contains the 
 fibers from the two hemispheres of the cerebellum. The 
 corpus callosum was the connection between the two parts 
 of the cerebrum ; the pons is the connection between the 
 two parts of the cerebellum. 
 
 Section. A picture or view of a part or body that would be seen if 
 it were cut by an intersecting plane. If the cut is made across, 
 the section is transverse; if lengthwise, it is called a longi- 
 tudinal section. 
 
 Spinal nerves. Nerves that have an attachment with the spinal 
 cord. They comprise nerves going to the cord and nerves 
 coming away from the cord. 
 
 Stomach. An enlargement of the alimentary tract that serves to 
 hold food while it is being acted upon by digestive juices se- 
 creted by the stomach. 
 
 Trachea. The tube connecting the lungs with the mouth and nose 
 cavities. 
 
 Vaso-motor. Refers to movement produced in the blood vessels. 
 This movement may be constriction in which the lumen grows 
 smaller ; or it may be dilatation in which the lumen grows 
 larger. Vaso comes from vas, meaning vessel. Constriction of 
 the vessel is called vaso-constriction ; dilatation of the vessel 
 is called vaso-dilatation. 
 
 Waste. The waste substances in the body result from the chem- 
 ical changes that go on in the production of energy. Ashes 
 represent the waste of combustion when wood and coal are 
 burned. The waste of the cells of the body is represented by 
 such substances as carbon dioxide, urea, uric acid, creatin, 
 xanthin, etc. 
 
CHAPTER V 
 THE SKELETON FRAMEWORK OF THE BODY 
 
 I. The Use of the Skeleton. 
 
 For attachment of muscles 
 For support and protection 
 For movement 
 II. Parts of the Skeleton. 
 The skull 
 
 The vertebral column 
 The thorax 
 The shoulder girdle 
 The arm 
 The leg 
 
 III. The Structure of a Long Bone. 
 
 IV. The Composition of Bone. 
 V. Joints. 
 
 Motion in movable joints 
 
 The use of the skeleton. There are some animals, such 
 as the slug and the jelly fish, that do not possess any hard 
 part corresponding to a skeleton. Such an animal if it lives 
 on land, lies flat on the ground, and moves slowly and with 
 difficulty. Animal life in its lowest forms is characterized 
 by a resemblance to plants ; in fact, in the case of bacteria* 
 it is not known whether they are plants or animals. Plants 
 in both high and low forms are characterized by their im- 
 mobility. Animals in their evolution from lower to higher 
 forms have increased their power to move about. So far 
 as movement on land is concerned, the feature that brought 
 an increased range of movement was the bony skeleton. 
 
 72 
 
The Skeleton Framework of the Body 73 
 
 Evolution is a slow and gradual process and the skeleton of 
 man is the result of centuries of development. 
 
 For attachment of muscles. The bones that form the 
 skeleton of man (Fig. 43) make possible not only movement 
 of the body itself but also of its parts. Muscles attached 
 to two bones, on contracting and shortening, pull the two 
 bones toward each other. If the bone at one attachment is 
 held in a rigid way, the contraction will result in a move- 
 ment of the other bone toward the fixed part. We say, 
 therefore, that bones serve for the attachment of muscles 
 and give support from which the muscles can pull. 
 
 For support and protection. Bones also give support to 
 the body. Man could not be an erect animal if there were 
 not a rigid skeleton to support his organs" and parts. In 
 addition, the bones serve for protection, for even in man, 
 so capable of self-protection, it is necessary to have the skele- 
 ton to protect some of the delicate organs. Some animals 
 have developed for protection other means also. The scales 
 of the fish, the quills of the porcupine, the heavy fur of arctic 
 animals, serve to protect these animals from various forces in 
 their separate environment.* 
 
 In man the bones that protect the vital organs are flat, 
 as the breastbone and shoulder blade, the ribs, which pro- 
 tect the heart and lungs, and the skull bones, which protect 
 the soft and delicate brain. 
 
 For movement. Bones serve for the attachment of 
 muscles, they give support and protection, and they in- 
 crease the possibilities of movement of the parts of the body. 
 The muscles by their shortening accomplish very simple 
 and imperfect motions ; by using the bones for support and 
 as levers, this motion is changed in rate, direction, and place 
 of application. 
 
 The long bones of the arms and legs, with the fingers and 
 toes, have motion as their chief function. The ribs are flat but 
 they are the longest bones in the body in proportion to their 
 
74 
 
 Healthful Living 
 
 Cranium. 
 
 (Clavic/eJ Co/Jar Son e. 
 
 (Scapula]. 
 Shoutc/er Blade 
 
 tfumerus. 
 
 Pe/vic one 
 Cav/'fy of Pelvis 
 
 Pate/la ftfnee C0pJ 
 
 Tarsa/s 
 
 'asa/Bones. 
 
 Ma/arfCheekjBone. 
 Superior Maxil/ary Bones. 
 Inferior Maxillary Hone. 
 Spinal Column Cervical Region. 
 
 fSternurnJSreastSone. 
 
 Ribs. 
 
 Spinal Column 
 
 Radius. 
 Ulna. 
 
 tatersals 
 -Phalanges 
 
 FIG. 43. The skeleton. 
 
The Skeleton Framework of the Body 75 
 
 size, and enable us to perform the important motions of 
 breathing. Yet they are classed as flat bones, for they lack 
 the round shaft and enlarged ends or heads which typical 
 long bones have. Even the bones of the instep, palm, 
 fingers, and toes, which are the smallest of the long bones, 
 have the shaft and heads. 
 
 Many of the small, short bones are stronger than the long, 
 slender bones, or the flat, thin ones. These bones are called 
 irregular bones. They are not easily broken and their chief 
 function is support. They are found in the spine, the 
 ankle, the wrist, the knee, and the face. We should re- 
 member that the irregular bones also assist in the two other 
 functions of protection and motion ; also that the long bones 
 and the flat bones are not confined to one function but par- 
 ticipate in all three functions (Fig. 43). 
 
 Parts of the skeleton. The central part of the skeleton 
 called the vertebral or spinal column, forms a firm but 
 flexible axis. The head rests upon the top of this column. 
 The ribs are attached at its side to make the walls of the 
 chest. The shoulder girdle rests upon the chest, and the 
 hip girdle is attached to the base of the spinal column. These 
 girdles connect the upper and lower limbs with the trunk. 
 The bones of the head and trunk form the axial skeleton. 
 The bones of the girdles and limbs are called the appended 
 skeleton, since they are appended to the axial framework. 
 
 The skull (Fig. 44). The skull is the cranium, or casket 
 which contains the brain, and the facial bones. The arched 
 form of the skull is the best shape for resisting blows and 
 pressure. Its bones are so firm and hard that bullets some- 
 times glance from it, but the structures within the skull are 
 so important and delicate that in war the head is protected 
 by a metal helmet to resist shrapnel. The occipital bone 
 curves under at the back of the neck to aid in forming the 
 floor of the skull. It has two projections called condyles* 
 (knuckles) situated just behind its junction with the sphenoid 
 
7 6 
 
 Healthful Living 
 
 HyoidJBone 
 
 (wedgelike) bone. The condyles fit into depressions (Fig. 45) 
 in the uppermost vertebra; thus the head rests and rocks 
 
 upon the spinal 
 column. Grasp 
 the neck with 
 both hands so as 
 to hold it motion- 
 less and stiff, and 
 find whether the 
 head rocks for- 
 ward and back- 
 ward, or side wise. 
 Between the con- 
 dyles is a large 
 opening through 
 which the spinal 
 cord goes from the 
 
 FIG. 44. Side view of skull. The larger bones brain, 
 are named in the figure. The lower jaw is dropped jr^ g ver teoraZ col- 
 down. Its socket in the skull is shown in front of 
 
 the opening of the ear, a; b, process of temporal Utnn. The Spinal 
 
 passing to malar, or cheek bone. Locate one of co lumn consists 
 
 in the adult of 
 twenty-six bones 
 (Fig. 45). Twenty- 
 four of these bones 
 have a similar 
 shape, and each is 
 called a vertebra 
 (Latin, that which 
 turns) . The other 
 
 two have the names of sacrum and coccyx. The first seven 
 vertebrae are in the neck and are called cervical (of the neck) . 
 The next twelve are those to which the ribs are attached 
 and are called thoracic or dorsal (of the back). The next 
 five vertebrae are in the loins or lumbar region and are 
 
 the condyles or projections which rest in sockets 
 on the highest vertebra; the hyoid bone, not joined 
 to any other bone, except by muscles ; opening of 
 ear and styloid process. A small part of the 
 sphenoid bone is shown ; the main part is at base 
 of skull. The eight cranial bones are : 
 
 One Frontal (forehead) 
 One Occipital (back and floor) 
 Two Parietal (sides and roof) 
 One Sphenoid (central floor) 
 Two Temporal (sides) 
 One Ethmoid (front floor) 
 
The Skeleton Framework of the Body 
 
 77 
 
 called lumbar (of the loins). They 
 are the largest of the vertebrae. 
 The lowest lumbar vertebra rests 
 upon the sacrum (sacred, because 
 this bone of lower animals was 
 once used in sacrifice). In infancy 
 the sacrum consists of five ver- 
 tebrae ; these begin uniting at two 
 years of age and complete the 
 union at twenty years. The 
 coccyx (cuckoo, from its resem- 
 blance to the bill of a cuckoo), or 
 last bone of the column, is that 
 part of the skeleton which in the 
 lower animals forms the tail. In 
 infancy it consists of four small 
 bones which later unite into one. 
 The coccyx is of little use, -but the 
 sacrum is a highly important bone, 
 since to its sides are attached the 
 bones of the pelvic arch, by which 
 the weight of the body is trans- 
 mitted to the legs. 
 
 Vertebrae. The different ver- 
 tebrae all conform to a general plan 
 of structure. On examination they 
 show a large massive central part 
 (the body), and leading from this 
 part and running posteriorly (back- 
 ward) are two processes of bone, 
 the pedicles (Fig. 46, A). The 
 pedicles are continuous with two 
 other parts, the laminae, and with 
 them form the neural arch. Where 
 pedicles and laminae join there runs 
 
 ..J 
 
 FIG. 45. Spinal column 
 (seen from behind) . s, spinous 
 process ; t, transverse process. 
 Find the 7 cervical, 12 tho- 
 racic, 5 lumbar vertebrae. Do 
 the sacrum and coccyx show 
 evidence of having been di- 
 vided in early growth ? 
 
Healthful Living 
 
 off horizontally to each side a process, the transverse pro- 
 cess. The laminae at their junction behind meet the spinal 
 process, which points directly backward. 
 
 Neuro/ CanaJ 
 
 -So/nous Process 
 
 Lom/na 
 Transverse f roc ess 
 
 Opening for J?x>l 
 of Sprna/ Ner ve 
 
 Spinovs 
 Process 
 
 FIG. 46. A, plan of a typical vertebra showing rib attachment; B, 
 side view of several vertebrae showing inter-vertebral fibre-cartilage and 
 openings for spinal nerves. 
 
 The arches formed by the pedicles and laminae serve 
 admirably for protection to the highly specialized spinal 
 cord (part of the nervous system). The processes are well 
 adapted by their roughened surfaces for the attachment of 
 muscles and ligaments. Strictly speaking, however, the 
 rough places on the bones are caused by the pull exerted by 
 
The Skeleton Framework of the Body 
 
 79 
 
 the muscles at the point of attachment. Between the 
 bodies of the vertebrae are elastic cushions (Fig. 46, R) 
 called fibro-car- 
 tilages. 
 pads are 
 
 These 
 of im- 
 portance in pre- 
 venting jar to the 
 spine, arid they 
 assist greatly in 
 all movements of 
 the spine. It will 
 be seen, therefore, 
 that the spine 
 is constructed to 
 support the head, 
 to keep the trunk 
 erect, to protect 
 the spinal cord of 
 the nervous sys- 
 tem (Fig. 47) , and 
 to allow motion of 
 the spine. This 
 last function is 
 provided for by 
 the separate ver- 
 tebrae, which 
 means, of course, 
 that each verte- 
 bra need move 
 only a little to 
 get a resulting 
 large movement. 
 The whole is 
 equal to the sum 
 of its parts. 
 
 /Verves to Neck. 
 
 Nerves to Lower 
 A bdorxen and 
 
 Sciatic Nerve (o Leg. 
 
 FIG. 47. Spinal cord in the vertebral column, 
 showing segments of cord and emergence of nerves 
 going to arms, trunk, and legs. (After Dejerine 
 and Thomas in Starr.) 
 
8o 
 
 Healthful Living 
 
 CfRV/OAL CURVE 
 Arc of 18 degrees 
 Radius of Arc 6% in 
 
 THORAC/C- 
 
 Arc of 42 degrees 
 Radius of Arc 12 %/ 
 
 Curves of the Spine. When the vertebral column is 
 viewed from the side (Fig. 47), it shows four curves. The 
 
 cervical curve starts 
 with the first verte- 
 bra and extends to 
 the second thoracic 
 vertebra. It is con- 
 vex forward. The 
 thoracic curve be- 
 gins with the second 
 thoracic and ends 
 with the twelfth tho- 
 racic. This curve is 
 concave forward. 
 The lumbar curve 
 begins with the 
 twelfth thoracic and 
 ends at the junction 
 of sacrum and fifth 
 dorsal. It is convex 
 forward. The sacral 
 curve completes the 
 picture with a deep 
 concavity forward. 
 Figure 48 represents 
 the curvature in these 
 sections. The degree 
 represents the num- 
 ber of degrees in a 
 segment of a circle 
 of which this curve 
 
 * S tne arc< 
 
 -LUMBAR CUffVf 
 
 Arc of 8O degrees 
 Radius of Arc 5%in. 
 
 SACRAL 
 
 Arc ofJ25 degrees 
 Radius of Arc 2% in. 
 
 FIG. 48. Normal curves of the spine. m 
 
 Notice that the spine is faced in the opposite figures given in inches 
 direction from the one shown in Fig. 47. A i j 
 
 These curves are normal. They should not ^Present the radlUS 
 
 be changed because the body is injured. of each segment. 
 
The Skeleton Framework of the Body 
 
 81 
 
 The thoracic and sacral curves are called primary curves 
 because they are present when the child is born. The 
 cervical and lumbar curves are compensatory or secondary, 
 because they develop after birth by the effort the child 
 makes to hold up its head and to walk erect. Now, the im- 
 portant thing for us to remember is that nature provides us 
 with a backbone that has curves. These curves are normal 
 and they should be maintained. Some boys and girls stoop 
 over so much that they increase the thoracic curve. This 
 destroys their good appearance and also interferes with 
 the development 
 of their lungs. 
 Girls by improper 
 modes of dressing 
 often increase the 
 lumbar curve too 
 much. This re- 
 sults in a weak 
 and painful back. 
 
 The thorax. - 
 The thorax, or 
 chest, is formed 
 in the rear by the 
 twelve thoracic 
 vertebrae; in front, 
 somewhat parallel 
 to the spinal col- 
 umn, but approaching it above, is the sternum, or breast- 
 bone (Fig. 49). 
 
 Twelve ribs curve around each side. Each rib joins one 
 of the thoracic vertebrae behind. The first seven pairs 
 directly join the sternum in front by means of short carti- 
 lages, and are called true ribs. The next three pairs, called 
 false ribs, do not reach the sternum, but each rib unites to 
 the rib above by a long cartilage. The last two pairs are 
 
 FIG. 49. Front view of thorax and shoulder 
 girdle showing projection of heart on chest wall. 
 
82 
 
 Healthful Living 
 
 called floating ribs, since the front ends are not attached 
 to a bone either directly, like the true ribs, or indirectly, like 
 the false ribs, but rest in the mus- 
 cular walls of the waist (Fig. 50). 
 
 The shoulder girdle. The arms 
 are attached to the trunk by the 
 shoulder girdle. This consists of 
 four bones, two on each side, scapulae 
 or shoulder blades, and the clavicles, 
 or collar bones. Each shoulder is 
 composed of a clavicle (key, from its 
 resemblance to the ancient key) and 
 a scapula (Fig. 51). The scapula 
 (trowel) occupies the rear part of the 
 shoulder. It is a large flat bone of 
 triangular shape and bears in the 
 end at the angle of the shoulder a 
 shallow socket into which is fitted 
 the end of the upper bone of the arm. 
 The clavicle is a slender bone, round 
 and slightly curved, which occupies 
 the front of the shoulder, and is 
 joined at one end to the scapula arid 
 at the other to the sternum. The 
 clavicles can be felt at the right and 
 left of the base of the neck. 
 
 The arm. The arm consists of the upper arm, forearm, 
 wrist, and hand (Fig. 51). The upper arm extends to the 
 elbow and has only one bone, the humerus. From the 
 elbow to the wrist is the forearm, formed of two bones, 
 arranged parallel to each other ; the ulna is on the inner side, 
 the side corresponding to the little finger ; the radius oc- 
 cupies the outer side, the same side as the thumb. At the 
 lower end of each, a bump may be felt, the bump on the 
 ulna being larger. The wrist is called the carpus,* and is 
 
 FIG. 50. Side view of 
 thorax, spine, and pelvis. 
 
The Skeleton Framework of the Body 83 
 
 composed of eight small bones arranged parallel in two rows, 
 four in each row, running across the wrist. Next follows 
 
 -- Scapula 
 
 Femur 
 
 Humerus 
 
 Patella 
 
 Utna 11 \ Radius 
 
 Fibula 
 
 TUbfa 
 
 Carp&fs--- 
 Afetacarpals 
 
 -Phalanges 
 
 FIG. 51. The arm and 
 the shoulder. Seen from 
 the rear. Why do the 
 fingers seem so long? 
 
 Tarsals 
 
 Metatarsafs--; 
 
 -Phalongt 
 
 FIG. 52. Bones of the 
 hip and leg. Front view. 
 
 the metacarpus* (beyond the carpus) (Fig. 51), or the bones 
 in the palm of the hand. The palm is composed of five 
 long bones, each serving to support a finger or thumb. Each 
 
84 Healthful Living 
 
 finger is composed of three small bones called phalanges 
 (rows of soldiers) ; the thumb has only two. The thumb is 
 more movable than the fingers, and can be opposed to each 
 of them. 
 
 The leg. The skeleton of a lower limb has a striking 
 resemblance to that of an upper limb (Fig. 52). The hip 
 
 Fifth Lumbar Vertebra- 
 
 -Sacrum 
 
 A cetabulum 
 
 \H\M\\\ :N>V.X '^W UKon-amcr / MWfVf/amammtmri 
 
 Coccyx 
 
 FIG. 53. The pelvis. 
 
 girdle, corresponding to the shoulder girdle, forms the hip. 
 The hip bones, or innominate (nameless, because they do not 
 resemble anything) bones, are large, flat, and somewhat 
 semicircular in shape. They meet in front (Fig. 53), but 
 behind they join the portion of the spinal column called the 
 sacrum, which separates them and forms, as it were, the 
 keystone of the arch. Thus is formed a large band of bone 
 inclosing a basin-shaped space, called the pelvis (basin), 
 which contains the bladder, rectum,* and generative organs. 
 There is a deep socket at the side in each innominate bone. 
 This socket is occupied by the round head found on the 
 upper end of the thigh bone, or femur. The femur is the 
 largest and longest bone in the body (Figs. 54. 55). 
 
The Skeleton Framework of the Body 
 
 The leg below the knee, like the fore- 
 arm, is composed of two parallel bones. 
 
 They are unequal in size, like the radius 
 
 and ulna. One, called the tibia, is much 
 
 larger than the other, the fibula (Fig. 52). 
 
 The latter bone is merely a brace to the 
 
 large tibia, which forms the joints with the 
 
 femur above and the foot below. There 
 
 is a bony disk embedded in the great ten- 
 don over the knee, form- 
 ing a protection to the 
 knee joint ; this is called 
 the patella, or knee-pan. 
 In which direction can 
 you move the patella to 
 and fro with the hand, 
 when the leg is straight 
 and the heel resting upon 
 the floor? 
 
 Like the hand, the foot 
 consists of three parts. 
 The tarsus,* or ankle, is FIQ 5 J_ Front 
 formed of seven bones, view of femur, 
 although the carpus has bonTfo^artlcuiat- 
 
 eight. The metatarsus,* ing with hip bone ; 
 
 like the metacarpus, is 6 ' sh , aft; c and f* 
 
 rough processes to 
 Composed of five bones, which muscles are 
 
 arranged parallel to one 
 another, which serve for ulates with tibia, 
 the base of the toes. The 
 toes have the same number of bones as 
 the fingers, and have the same name, the 
 phalanges. 
 
 The Structure and Hygiene of the Foot. It is important 
 to understand what the human foot is like, because abuse of 
 
86 
 
 Healthful Living 
 
 the foot is so common and the value of strong, sound feet 
 is so great. The foot must support the weight of the body 
 
 and in addition must serve 
 to transfer the weight of 
 the body from the heel to 
 the toe in walking. 
 
 1. The bones are ar- 
 
 FIG. 56. Skeleton of foot, If the 
 
 child never goes barefooted, the arch is ranged to Jorm an arch. 
 likely to become flattened instead of J n ^ Q g rg ^ pl ac(3j the bones 
 
 of the foot are arranged to 
 
 form an arch extending from the toes to the heel (Fig. 56). 
 This arch is low on the outer side of the foot and here the 
 tissues covering the bones are in contact 
 with the ground (Fig. 57). On the inner 
 side, however, that arch is high and is held 
 in place by ligaments on its under surface, 
 and by small muscles (Fig. 58) attached to 
 the bones of the foot, and by the tendons 
 from the calf muscles which pass under this 
 part of the foot on the way to the toes. In 
 addition, the heel bone (os calcis) is placed 
 more to the outer side of the foot. As 
 regards the use of the foot, these anatomic 
 facts mean that the weight of the body can 
 be carried on the outer side of the foot to 
 the best advantage. We should use the 
 body in conformity with the laws of its 
 construction. In this way we shall be 
 more efficient. In walking, therefore, the track made by a 
 
 . T . i i i ^ n ,1 i p ,1 natural foot. Make 
 
 weight should tall on the outer side ot the a test by wetting 
 
 foot (Fig. 57). your foot and notic- 
 
 ~ rm 777 JT 7 ing the track made 
 
 2. The muscles help to support the arch upon the floor. 
 and the muscles must be used correctly. In 
 the second place, the muscles on the under surface of the 
 foot (Fig. 58) must be kept strong and the muscles of the 
 
 FIG. 57. The 
 
The Skeleton Framework of the Body 
 
 87 
 
 calf, going to the toes, must be exercised. It is important, 
 therefore, to walk with the feet parallel. This will more 
 readily bring the weight on the outer side and in addition 
 will allow better action of the foot muscles. If the feet 
 are turned outward in walking (Fig. 59), the weight of the 
 body will be transferred to the inner side of the foot just 
 over the arch instead of passing forward 
 over the toes (Fig. 60). The feet should 
 not be turned inward, "pigeon-toe." The 
 parallel position only is correct. 
 
 3. Shoes must not distort the bony ar- 
 rangement of the foot. Shoes must not 
 cramp the toes or press the toes outward. 
 This occurs in pointed shoes and prevents 
 the proper action of the foot muscles 
 (Fig. 61). 
 
 4. Shoes must not throw strain upon the 
 foot. If the foot is to remain useful and 
 efficient, the arch must not be subjected to 
 a change in position of the bones of the 
 foot. High heels throw the bones of the 
 arch out of position and prevent proper 
 
 foot action (Fig. 62). Women who wear FIG. 58. Sole 
 high heeled shoes are as barbarous in this %% themus- 
 respect as the Chinese women who bound cies and tendons 
 th P f A pt that bend the toes 
 
 and support the 
 
 The structure of a long bone. If a long arch. 
 bone is sawed through lengthwise (Fig. 63), 
 it will be observed that there is a central cavity containing 
 yellow marrow.* (What cut of steak has a marrow bone?) 
 We should observe also that the portions inclosing this 
 cavity are of a dense solid structure, but that the bone is 
 spongy near the ends, enlarged for forming the joints. The 
 cavities in this spongy portion contain red marrow. A long 
 bone is hollow. A given weight of material has more 
 
88 
 
 Healthful Living 
 
 strength in the form of a hollow cylinder than in the form 
 of a solid rod. (Does this imply that a hollow cylinder is as 
 strong as a solid one of the same size?) 
 The composition of bone. Bone is 
 covered with periosteum. This is the 
 name given to the close clinging fibrous 
 covering of the bone, composed of con- 
 nective tissue and blood vessels. If we 
 remove the periosteum from the surface, 
 the red marrow from the pores, and the 
 yellow marrow from the larger cavity, 
 we have remaining the true bony sub- 
 stance. Yet even this is not one sub- 
 stance, but consists of mineral matter 
 and animal matter in the proportion of 
 two parts of the 
 
 latter. The animal 
 
 matter is gelatin,* like the substance 
 composing the white fibrous part of con- 
 nective tissue. The mineral matter is 
 chiefly phosphate of lime and carbonate 
 of lime. 
 
 The mineral matter may be removed 
 by soaking the bone for several days in 
 strong vinegar or in dilute muriatic acid. 
 The bone is then flexible but tough. If 
 a slender bone, such as a hog's rib, has 
 been used, it can be tied in a knot ; after 
 the acid has been washed off, it may he 
 preserved in dilute alcohol as a curiosity, other. 
 
 FIG. 60. In walk- 
 
 The weight 
 
 The animal matter mav be removed by should be placed on the 
 
 outer borders of feet. 
 
 holding the bone on a shovel in the fire 
 
 for a sufficient length of time. The mineral part remaining 
 
 is very light and brittle, and weighs much less than the 
 
PLATE IX. X-ray of ankle, showing tarsus and lower end of tibia 
 and fibula. Notice the bony arch. 
 
The Skeleton Framework of the Body 
 
 original bone, the form of which it still 
 
 preserves. 
 
 Joints. The meeting of the ends 
 
 of two bones makes a joint and this 
 
 joint is held together by bands of con- 
 nective tissue, called ligaments. Liga- 
 ments are composed of white fibrous 
 
 tissue. Are they tough? Are they 
 
 elastic or non-elastic? The way the 
 
 bones are placed in the body to allow 
 
 movement is shown in the X-ray 
 
 picture (Plate IX). The shadow 
 
 shows the outline of the ankle with the 
 
 bones of the tarsus and the lower end 
 
 of the tibia and fibula. The ligaments 
 
 holding the bones to form the ankle 
 
 joint do not show in an X-ray. This 
 
 picture indicates how the bones are 
 
 kept together and yet are free to move 
 
 one upon the other. 
 
 Now all joints are not alike in the 
 
 movement they allow. Some have very little motion ; others 
 
 move freely and over quite a range. The bones forming the 
 
 skull have practically 
 no motion in adult life 
 and they are called 
 fixed joints. They are 
 remarkable in that the 
 bones fit into each 
 other by toothed edges, 
 forming irregular lines, 
 known as sutures. 
 Other joints which we 
 shall study have a free 
 type of movement. 
 
 FIG. 61. The track 
 made by a foot in which 
 the natural arch has been 
 partly broken down by 
 tight shoes. If the arch 
 breaks down" entirely the 
 foot is called flat foot. 
 
 _Jmportent 
 Ligament Supporting 
 the Arch. 
 
 FIG. 62. After wearing high heels the 
 small bones of the foot are adjusted to a cer- 
 tain position. If a sudden change is made 
 in height of heel, pain and disability follow. 
 Pain in the knees and hips follows wearing 
 high heels. 
 
Healthful Living 
 
 Let us take the knee joint, for example. The two bones 
 which join are the femur and the tibia. They present to 
 each other an enlargement, or head, which serves to increase 
 the strength of the joint and increase the 
 surfaces applied to each other. The 
 two heads instead of being formed al- 
 together of rigid bone are covered by 
 cartilage, which by its elasticity and 
 smoothness provides for the gliding of 
 one bone upon the other. Strong 
 fibrous bands called ligaments bind to- 
 gether the ends of the two bones. Sur- 
 rounding the ends of the bones, like a 
 collar, is found a ligament (the capsular 
 ligament) inclosing the space of the joint 
 in a closed sac. This closed sac is called 
 the capsule. A thin membranous sac, 
 called the synovial membrane, lines the 
 capsule. It secretes a slimy fluid which 
 resembles the white of an egg and is 
 called the synovial fluid. This lubri- 
 cates the joint, and is deposited con- 
 
 tinuaU y> but on 'y so fast as used p in 
 
 length, exercise. As the sac has no opening, 
 cxc i uc i e d, and atmospheric pres- 
 
 , . ' 
 
 porting c, the upper sure aids in holding the bones in place. 
 
 and lower articular The ^ . ^ ^ ^ and ^ . { 
 surfaces; d, compact 
 
 bone forming the shaft ; have the same parts as the knee joint. 
 
 e, marrow cavity; /, J t fe mrely that twQ boneg t to _ 
 periosteum. 
 
 gether so perfectly are forced from 
 their natural places. When this happens it is called a 
 dislocation. 
 
 Motion in movable joints. Not all movable joints can 
 be moved in a similar way. We can move the knee joint 
 in two directions, forward and backward. The shoulder 
 
 along its 
 
 o. struts and stays of air 
 
 b, spongy bone sup- 
 
The Skeleton Framework of the Body 
 
 joint is capable of more and wider movements. There are 
 four varieties of movement in the joints of the body. 
 
 1. Gliding Motion. This is the simplest kind of move- 
 ment. It is the rubbing of one surface on another and it is 
 small in extent. Ex- 
 amples of this move- 
 ment are found in the 
 
 carpal and tarsal bones 
 of the hand and foot. 
 
 2. Angular Motion. 
 This type of motion 
 occurs in only one 
 plane. It is seen in 
 what is called a hinge 
 joint. Does a door 
 swing in one plane? 
 The human body has 
 four varieties of angu- 
 lar movement, two in 
 the forward and back- 
 ward direction (the 
 antero-posterior* plane 
 of the body) and two 
 
 in a sideward direction FIG. 64. The right hip joint. The hip 
 
 (movement from an 
 
 antero-posterior plane 
 
 of the body) (Fig. 
 
 65). 
 
 (a) Flexion in a joint is always in an antero-posterior 
 plane of the body. The angle formed by the parts grows 
 smaller during the movement. When the body bends for- 
 ward, flexion occurs. Show flexion of the head, the fingers, 
 the knee joint, the ankle joint. 
 
 (6) Extension in a joint is always in an antero-posterior 
 plane and the angle becomes greater. The fingers are ex- 
 
 bone sawed through so as to show the cup 
 of the joint, a, head of femur in acetabu- 
 lum ; 6, ilium bone of pelvis; c, capsular liga- 
 ment; /, femur; i, ischium bone of pelvis; 
 r, round ligament of hip joint; s, sacrum. 
 
92 Healthful Living 
 
 tended when they are stretched out straight. Show flexion 
 and extension of the hip joint. 
 
 (c) Abduction is movement outward from an antero- 
 posterior plane of the body and the angle increases in size. 
 
 FIG. 65. Diagram of a cross section of trunk showing planes and 
 directions. 
 
 Raise the arm directly to the side. This is abduction of the 
 arm. What is abduction of the head ? Of the leg ? 
 
 (d) Adduction is movement toward an antero-posterior 
 plane of the body, and the angle between the parts decreases 
 in size. Show adduction of the leg. 
 
 3. Circumduction. This movement is a combination of 
 flexion, extension, abduction, and adduction. The end of the 
 
The Skeleton Framework of the Body 93 
 
 moving part describes a circle and the part itself describes the 
 sides of a cone (Fig. 66). Show circumduction of the arm. 
 
 FIG. 66. Circumduction the extremity (hand) describes a circle 
 and the part describes the sides of a cone. 
 
 4. Rotation. In this movement, the moving part turns 
 around its own axis. Show rotation of the head. Show 
 circumduction of the head. 
 
 GLOSSARY 
 
 Antero-posterior. A compound word made up of anterior and 
 posterior to denote a direction or plane passing from the an- 
 terior (front) part of the body to the posterior (back). If 
 the anterior plane is a plane parallel to the front of the body 
 and the posterior to the back of the body then it follows that 
 there are innumerable antero-posterior planes and they will 
 all be perpendicular to the anterior and posterior planes. 
 
 Bacterium. The plural form is bacteria. They are small cells, 
 spherical, rod-shaped, or spiral in form. Some are capable of 
 causing disease in the body, but most of them are harmless. 
 They are widespread in nature. 
 
 Carpus. The eight small bones which form the wrist. 
 
 Condyle. An enlarged and prominent part of a bone. 
 
 Environment. All the external surroundings of an organism. 
 The air, climate, food, work, play, housing, clothes, etc., make 
 up the environment. 
 
 Gelatin. A hard, transparent, tasteless substance obtained 
 from animal tissue such as skin, hoof, and horns. It dissolves 
 readily in hot water. 
 
 Marrow. A soft, vascular tissue found in the cavities of bones. 
 It contains fat and many cells of the blood. 
 
94 Healthful Living 
 
 Metacarpus. That part of the hand between the wrist and 
 
 fingers. It comprises five bones. 
 Metatarsus. That part of the foot between the ankle and the 
 
 toes. It comprises five bones. 
 Rectum. The lower part of the colon. It is made of muscle 
 
 and mucous membrane and is richly supplied with nerves. 
 Tarsus. The seven small bones which form the ankle. 
 
CHAPTER VI 
 HYGIENE OF THE SKELETON 
 
 I. The Nourishment of Bones. 
 
 II. Broken Bones. 
 
 III. Dislocations and Sprains. 
 
 IV. Weak Feet. 
 
 Foot exercises 
 
 Characteristics of a good shoe 
 V. .Deformities of the Spinal Column. 
 Lateral curvature of the spine 
 Posterior curvature of the spine 
 VI. Posture. 
 
 Sitting 
 Lying down 
 Standing 
 Walking 
 VII. Essential Facts in the Growth and Development of Bones. 
 
 The nourishment of the bones. If a limb be disused 
 because of paralysis * or long sickness, the bones, as well as 
 the soft parts, lose in strength and weight. This shows that 
 the more vigorous circulation which comes with exercise 
 helps to rep'air the osseous tissue. The blood vessels that 
 supply the bones enter from the inner side of the periosteum. 
 We thus see why the bone shrinks away if the periosteum is 
 removed, and why the surgeon * is careful to leave as much 
 of the periosteum as possible in the case of bones splintered 
 by accidents. 
 
 The animal matter of bones is most abundant in childhood, 
 and a child's bones will bend before they break. If broken, 
 they heal rapidly. The animal matter is less abundant in 
 
 95 
 
g6 Healthful Living 
 
 the aged, therefore, the bones are brittle and more easily 
 broken, and they take longer to heal. 
 
 Broken bones. The two ends of a broken bone should 
 be brought together in their correct position as soon as 
 possible, before inflammation and swelling render this dif- 
 ficult. Of course, a surgeon should be called to set a broken 
 bone. If the patient has to be carried some distance, care 
 should be taken to prevent injury to the fleshy parts by the 
 ends of the broken bone; the limb should be bound with 
 handkerchiefs to a strip of board, or even to umbrellas or 
 walking sticks, as temporary splints. Learn the first aid 
 treatment for broken bones on page 419. 
 
 Dislocations and sprains. A dislocation * sometimes 
 breaks the ligaments surrounding it, producing inflamma- 
 tion.* This makes examination of it difficult, hence there 
 should be no delay in procuring the necessary skill and 
 restoring it to place. 
 
 A sprain * is an injury due to a sudden wrenching or tear- 
 ing of the ligaments, as a result of which a ligament is lacer- 
 ated or torn from its fastenings to the bone. A bad sprain 
 may be more serious than a fracture,* and result in stiffness 
 or in permanent weakness. Immediate rest is necessary. 
 A cold footbath immediately after spraining the ankle is 
 sometimes beneficial. If there is delay in treatment and 
 the joint swells, then use hot water. Careful rubbing, very 
 light at first and gradually increasing in vigor from day to 
 day, may shorten the period of recovery. Learn the first 
 aid treatment for a sprain on page 422. 
 
 Weak feet. In discussing the foot it was pointed out 
 that the feet are very important parts of the body. If we are 
 to be able to do the many things in games and work that we 
 will want to do we must have strong feet. Feet are not all 
 beautiful and many people are ashamed of their feet. That 
 is because they have deformed them by improper shoes and 
 improper methods of walking. Notice the well-shaped use- 
 
Hygiene of the Skeleton 
 
 97 
 
 ful feet in Figure 60. What would happen to the feet in 
 Figure 60 if placed in shoes of the type shown in Figure 62? 
 Foot exercises. To strengthen the muscles of the feet 
 the following exercises will be found useful : 
 
 1. Stand with the feet parallel about three inches apart. 
 Roll outward on the outer borders of the feet. 
 
 2. Stand with the feet parallel about three inches apart. 
 Raise on toes and then lower heels slowly with weight on 
 outer borders of the feet. 
 
 3. Walk on outer borders of the feet with the feet parallel. 
 
 4. Sitting, feet flat and parallel on the floor, raise the 
 arch by attempting to draw the toes toward the heel. 
 
 5. Same as number four standing. 
 
 Exercises to be done ten to twenty-five times daily. 
 
 Characteristics of a good shoe. The choice of a shoe that 
 will provide the necessary protection to the foot and that will 
 not injure the foot is 
 very important. Such 
 a shoe will have a heel 
 low and as broad as 
 that of the wearer. 
 The sole of the shoe 
 should be, in outline, 
 essentially the s'ame as 
 the outline of the foot 
 and especially it should 
 have a straight inner 
 line. The shoe should 
 fit tightly over the heel 
 and should grip the foot through the instep, leaving plenty of 
 room in the region of the toes. Compare the illustrations 
 in Figures 67, 68, and 69 and keep these points in mind when 
 buying your next pair of shoes. 
 
 Deformities* of the spinal column. This comes chiefly 
 on account of the yielding nature of the cartilage. The 
 
 FIG. 67. Shoes 
 should be made to 
 fit the foot. 
 
 FIG. 68. Feet 
 should not be 
 crowded to fit the 
 shoe. 
 
98 Healthful Living 
 
 extent of the compressibility of cartilage may be realized 
 if one's height is measured upon rising in the morning and 
 again at night, when the loss in height sometimes amounts 
 to nearly half an inch. The cartilages between the vertebras 
 
 FIG. 69. The two figures above represent young people who are victims 
 of a custom that is foolish : the Chinese are giving up foot-binding. The 
 lower figure represents young America, shod with healthful shoes, and 
 ready for work or play. 
 
 are very thick, so as to give flexibility to the spinal column. 
 This blessing also brings with it a danger of deformity. If 
 the head is bent forward continuously in study or work in- 
 stead of being held up, the upper cartilages are compressed 
 in front, the ligaments stretch, and a deformity of the neck 
 may result, causing the head to project forward. Working 
 
Hygiene of the Skeleton 
 
 99 
 
 with the desk low in front, or working upon the ground, 
 may cause round shoulders. 
 
 Lateral curvature of the spine. Tight clothing deforms 
 the ribs, which are early altered because of the long carti- 
 lages. The binding down of the 
 front ends of the ribs causes 
 posterior curvature of the spine, 
 with flat chest and round 
 shoulders. Lateral, or sidewise, 
 curvature (Fig. 70) of the spine 
 is caused by constantly carrying 
 the books, satchel, or other 
 weight in the same hand ; by 
 writing at a desk that is too 
 high; by hanging the head to 
 one side; and by improper and 
 insufficient food, so that the 
 muscles are weakened. Figures 
 71 and 72 show the improper 
 and proper ways to carry 
 books. It is important that 
 girls, especially, learn to carry 
 books in the proper way at all 
 times. 
 
 Posterior curvature of the spine. Posterior curvature is 
 caused by habitually bending over the work, and by slipping 
 down in the seat or desk (Fig. 73), " trying to sit upon the 
 small of the back." It is caused also by weakness of muscles, 
 by wearing shoes with high heels, and by writing at a desk 
 that is too low. In curvature of the spine, the cartilages 
 become V-shaped and the ligaments stretched. Shoulder- 
 braces should not be worn to correct round shoulders. If 
 they hold the shoulders back they are doing the work of the 
 muscles and so the muscles become weaker and less able to 
 maintain a good posture. Corrective exercises * are necessary 
 
 FIG. 70. Such a condition 
 prevents the boy or girl from 
 playing freely in games. In 
 most cases it can be prevented ; 
 in many, it can be corrected. 
 
100 
 
 Healthful Living 
 
 in many cases, and they should be given by the teacher of 
 physical education or the school physician: If an incorrect 
 posture is habitually assumed in walking, in carrying books 
 or otherwise, one should not expect to recover natural grace 
 of form by wearing a brace. Exercise of the neglected 
 
 FIG. 71. An improper 
 way to carry books. 
 
 FIG. 72. By distribut- 
 ing the books properly the 
 posture may be held easily 
 in correct position. 
 
 muscles, that is, opposite muscles, instead of those that were 
 used excessively while acquiring the deformity, is a great 
 aid. Posterior curvature has been improved by sleeping 
 on the back on the floor or on a hard mattress. 
 
 Posture. The bones are more or less flexible in child- 
 hood, so that the posture we assume while we are growing 
 children will determine and control, very largely, the shape 
 of our bodies when we become grown. If a young tree is 
 
Hygiene of the Skeleton - ;*\ \ , , \ \ ' *>> ici 
 
 bent, it grows into a crooked tree. What is that saying, 
 
 " As the twig is bent "? There are four positions 
 
 which must be cor- 
 rect so that grace, 
 strength, and con- 
 trol of the body 
 will result when wo 
 are adults. These 
 are the sitting, the 
 lying, the standing, 
 
 FIG. 73. Flat chest, 
 round shoulders, and 
 displacement of vital 
 organs are produced by 
 slipping forward on the 
 seat. 
 
 and the walking 
 positions. 
 
 Sitting. One 
 should sit in a chair 
 or at a desk so that 
 the trunk is kept 
 straight and any 
 inclination should 
 occur at the hip 
 joint. This not 
 only looks better 
 but it allows the organs in the chest and abdomen to act in 
 a free and unobstructed way. Select the good posture in 
 Figures 74 and 75, 
 
 FIG. 74. This position is not only hygienic but 
 also comfortable because the weight is balanced. 
 
. t e : Healthful Living 
 
 Lying down. When the body is reclining, all the muscles 
 should be relaxed. There should be no effort to hold the 
 body in any particular posture. Does that mean that there 
 is no instruction as regards lying? No! The proper lying 
 position is on the right side or partially on the face. 
 
 Standing. It must be remembered that the upright 
 position of man is an acquired position. A long time ago 
 the ancestors of man climbed and walked on "all fours." 
 
 It is also true that the 
 posture of man differs in 
 different races. The stand- 
 ing posture of the Chinese 
 is different from that of 
 the Englishman. The pos- 
 ture of people of the same 
 race varies because they 
 are expressing different 
 things in the way they 
 stand. This is a very im- 
 portant fact. The body 
 speaks all the time and 
 tells many things by the 
 position it takes in stand- 
 ing. We should be sure 
 that we are having it tell 
 the things that we are 
 willing to stand for. Ob- 
 serve the walk of people on the street and see if you can tell 
 what the3 r are thinking about or how they are feeling. What 
 do you express in your body as you walk to school. The 
 standing position in order to be most efficient must be in 
 balance. The weight must be carried on the balls of the 
 feet. This does not mean that the heels are not to touch 
 the ground. The head should be carried on top of the 
 chest and not projected forward as if it grew from the 
 
 FIG. 75. The sitting posture de- 
 pends upon proper seats. 
 
Hygiene of the Skeleton 
 
 103 
 
 FIG. 76. Good posture makes for health, happiness, and improves 
 personal appearance. Write a legend for A, B, and C that tells what the 
 girl is saying with her body. 
 
 FIG'. 77. The boy with good posture is not only a stronger and more 
 active boy, but his posture will be an asset in business or professional life. 
 A, body erect, weight over the balls of the feet. B, body relaxed, no control 
 and no balance, hence in a poor position for action. C, body stiff and bent 
 backward awkward. 
 
104 
 
 Healthful Living 
 
 front of the chest. Compare the postures in Figures 76 
 and 77. 
 
 Walking. In walking, the weight should be carried on 
 the outer side of the feet (Fig. 57), the feet should be placed 
 on the ground parallel to each other (Fig. 60), the chest 
 should be carried well forward (Figs. 76 A, 77 A), and the 
 arms should swing easily at the side. In Figures 71-77 tell 
 the good and bad points in the postures shown. 
 
 If the habits of the body in motion and at rest are in- 
 correct, if the parts are not clothed properly, the flexible 
 bones in childhood will be malformed. There are many who 
 suffer in adult life because they have worn improper shoes 
 and clothes, and have walked and sat in incorrect postures. 
 Bow legs are often caused by encouraging children to walk 
 
 while too young. They 
 may also result from im- 
 proper methods of feeding, 
 while infants. 
 
 Essential facts in the 
 growth and development 
 of bones. For proper 
 growth and development, 
 the bones must be used 
 correctly. Any constant 
 incorrect use will show in 
 distorted and crooked 
 bones, producing a form 
 that is less able to move 
 quickly and easily, and 
 hence a form that is less 
 efficient. Good food and 
 
 pure air brought by a vigorous circulation are essential. 
 Poor or indigestible food, stimulants,* and poisons affect 
 the health and strength of the bones. Surgeons report cases 
 of fracture occurring in persons having the alcohol habit, 
 
 FIG. 78. Appearance of the face of a 
 boy who did not have his adenoids re- 
 moved. (By courtesy of Dr. Frank S. 
 Mathews.) 
 
Hygiene of the Skeleton 105 
 
 where the bones would not unite by bony material, but 
 remained flexible and useless. Indulgence in alcoholic 
 liquors, especially wine, is a very common cause of gout, a 
 disease of the joints. Smoking in boyhood often prevents 
 the proper development of the long bones and a stunted 
 stature results. It must also be remembered that growing 
 parts are deformed by conditions that interfere with proper 
 functioning. In this way, adenoids may cause marked 
 deformity of the bones of the face (Fig. 78). 
 
 APPLIED PHYSIOLOGY 
 
 Exercise I 
 
 1. What are the common faults found in shoes and how do such 
 shoes injure the feet? Most people assume the following rule 
 in selecting a shoe : If you can just draw on a shoe without 
 much effort and sit with it on the foot for ten minutes, it will be 
 comfortable to walk in and wear all day. Yet such a shoe is one 
 size too small for walking. Many makers no longer number their 
 shoes plainly because of the vanity of some purchasers. A new 
 shoe should be as comfortable as an old one. Persons who, be- 
 cause of silly jokes about big feet or for other reasons, have the 
 idea that the shoe should leave no extra room, but should fit as 
 if it were covering a wooden foot, will always get uncomfortable 
 shoes. 
 
 2. If a shoe is too loose, it slips up and down at the heel and 
 chafes the sldn there. If too tight, there is pressure on the toes, 
 which causes a corn or ingrowing nail. Have your shoes been 
 correct or have they been too loose or too tight ? 
 
 3. How many sprained ankles have you known of? Were 
 the sufferers mostly boys or girls? Why? 
 
 4. What is the general arrangement of the bones of the foot? 
 Does the weight of the body come upon the middle of the arch? 
 How can this arch be injured and what is such a deformity called? 
 
 5. Why is it that people who grow up in warm climates are 
 more likely to have high arched insteps and elastic feet than those 
 who pass their childhood in cold climates ? 
 
io6 Healthful Living 
 
 Exercise II 
 
 6. What in the composition of a bone gives it stiffness ? hard- 
 ness? toughness? flexibility? 
 
 7. Should chairs and benches have straight backs ? 
 
 8. Why is a chair back that is very slanting often injurious? 
 Why is a very deep chair injurious if deep enough for the front 
 edge to strike the occupant behind the knee ? 
 
 9. Why does a young child usually crawl before it walks? 
 
 10. Which girdle is attached directly to the spinal column? 
 Which girdle is attached indirectly ? 
 
 11. Why is the arm so often dislocated at the shoulder? 
 
 12. High pillows may cause what deformity? 
 
 13. Should a young child be urged to stand or walk? 
 
 14. What part of a long bone is composed of compact tissue? 
 Of very porous tissue ? 
 
 Exercise III 
 
 15. Could the neck be broken and death result without break- 
 ing a bone ? 
 
 16. What would be the result if the ligaments were composed of 
 the yellow fibers of connective tissue instead of the white fibers? 
 
 17. If a child's feet be allowed to dangle from a high seat, what 
 will be the effect ? 
 
 18. When the palm is turned upward is the radius parallel or 
 crossed with the ulna? When the back of the hand is up? 
 
 19. Why should one always sit and walk erect ? 
 
 20. In a long bone what is chiefly a storage tissue, saving food 
 for future use? 
 
 21. Ligaments are of very slow growth. This accounts for the 
 tedious nature of the recovery from what kind of accidents? 
 
 22. Observe how many of your classmates sit " slid forward " 
 in the seat, and report in recitation the result of your count. 
 
 23. When the school is marching out, count those who walk 
 with the head protruded. 
 
 24. A " bone felon " is often caused by an infection beneath 
 the periosteum. Why should it be lanced ? 
 
 25. What is the first aid treatment for a fracture? A sprain? 
 
 Exercise IV 
 
 26. Is it correct to walk with the weight on the outer side of 
 the foot? Why? 
 
Hygiene of the Skeleton 107 
 
 27. Determine, by placing the wet feet on a piece of paper, 
 where the weight comes. Let the weight sag inward and observe 
 how this position increases the size of the imprint. 
 
 28. Make a tracing on paper of the feet in an abducted posi- 
 tion and in a parallel position. 
 
 29. Measure your height in the morning and evening of the 
 same day. Is there a difference? 
 
 30. Notice the difference in breathing while in the correct and 
 incorrect sitting position. 
 
 LABORATORY EXERCISES 
 
 Experiment 1. To study the organic and inorganic * parts of bone. 
 
 Material. Hog's rib, glass beaker, dilute muriatic acid, and 
 alcohol. 
 
 Method and observation. Place the rib 1 free from all muscle 
 and connective tissue in the beaker and cover with the acid. Leave 
 in the acid until the bone becomes elastic. When the mineral 
 (inorganic) matter has been dissolved, the bone can be easily bent. 
 Remove the excess of acid and preserve the rib in alcohol. 
 Experiment 2. To study the foot in relation to the shoe. 
 
 Material. White paper, ruler, and pencil. 
 
 Method and observation. Place the bare foot on the paper 
 and draw an outline of the foot. Measure with the ruler the width 
 of the foot in the instep region and the length of the foot from toe 
 to heel. Measure the width of the shoe in the same region as that 
 taken for the foot ; measure the length of the shoe. Compare 
 the two sets of measurements. 
 Experiment 3. To determine the proper height of the school seat. 
 
 Material. Ruler or yardstick. 
 
 Method and observation. With the foot flat on the floor measure 
 the length of the leg from the floor to the under surface of the 
 knee. How many inches is it? Measure the height of the seat 
 from the top of the forward edge to the floor. How many inches 
 is it? The leg measurement should be one inch more than the 
 seat measurement. Are your school seats adjustable. Are they 
 properly adjusted? 
 
 GLOSSARY 
 
 Corrective exercises. Exercises usually of a passive type at 
 first and later of an active type for the purpose of correcting 
 deformities of the skeleton. 
 
io8 Healthful Living 
 
 Deformity. A change from the normal. 
 
 Dislocated Displaced. The term here refers to the displace- 
 ment of a bone from its normal position in a joint. When 
 there is a dislocation, there results a deformity. 
 
 Fracture. A break. Used with reference to bones. A broken 
 bone is called a fracture. In a fracture, the deformity may 
 not be seen except by an X-ray. 
 
 Inflammation. A process in the body characterized in most 
 cases by heat, redness, swelling, and pain in the part affected. 
 
 Inorganic. Not being or having been a living organism. Refers 
 to substances in chemistry that relate to the world of metals 
 and their compounds. 
 
 Paralysis. Loss of the power of contractility in the voluntary or 
 involuntary muscles of the body. 
 
 Sprain. The injury to ligaments of a joint. This may be a 
 stretching, or, if severe, a real tearing. The word strain is 
 applied to the same sort of injury occurring in muscle. 
 
 Stimulant. A substance that excites action in the body whether 
 acting on the nerves through the skin or after getting into the 
 circulation. Typical stimulants acting on different parts 
 and in various ways are spices, mustard, camphor, ammonia, 
 strychnin, light, heat, electricity, joy, hope. 
 
 Surgeon. One who by training, skill, and experience is able to 
 treat injuries and conditions of abnormality by means of 
 manual methods or by the use of instruments. 
 
CHAPTER VII 
 
 THE MUSCLES AS THE MOTOR MACHINERY OF 
 THE BODY 
 
 I. What the Muscles Do. 
 II. Muscles and Nerves. 
 
 III. Kinds of Muscles. 
 
 Voluntary 
 
 Involuntary 
 
 Cardiac muscular tissues 
 
 IV. Voluntary and Involuntary Muscles Compared. 
 V. The Attachment of Muscles. 
 
 VI. How Muscles and Bones Cooperate. 
 VII. Names and Positions of Muscles. 
 
 What the muscles do. We have learned that motion 
 is one of the properties of protoplasm. What are the other 
 properties? A very interesting fact of physiology is that 
 the cells of the body, such as muscle, nerve, skin, and bone 
 cells and the cells of the different organs, have become 
 specialized through the development of a certain property 
 at the expense of other properties. For example, the muscle 
 cell has developed to a high point of efficiency the property 
 of contraction ; the nerve cell has specialized in conductivity 
 and irritability. This specialization of function was re- 
 ferred to under the head of division of labor. How does 
 this same principle work in the society of men? Movement 
 of the body, which is made possible by this specialization 
 of muscle, is one of the essentials of life. The individual who 
 cannot move is handicapped greatly, and the ability to move 
 
 109 
 
no Healthful Living 
 
 easily, gracefully, and with the body in control is greatly to 
 be desired. 
 
 Muscles and nerves. Now, the one essential condition 
 for contraction of the muscles is stimulation by the nerves. 
 If an impulse is not sent to the muscle, the muscle cannot 
 contract. Therefore, it must be remembered that the 
 muscle and its nerve are to be thought of as a unit. For 
 this reason the strength of a muscle is not dependent en- 
 tirely upon its size. People who think that large muscles 
 are a sign of health, and that large muscles give strength and 
 vigor, are very much mistaken, if they depend only upon 
 muscular strength. The development of the will is very im- 
 portant. The body has been compared to a steam engine. 
 To what parts of the engine may the muscles be compared ? 
 
 We are hearing a great deal to-day about eugenics.* This 
 word means " favorable birth." The eugenic movement 
 aims to improve the physical, mental, and moral qualities 
 of the race. It seeks to improve the quality of life in the 
 nation. Now muscle and nerve tissues will have a good 
 heredity,* they will be strong and efficient in proportion to 
 the vigor and strength of the protoplasm from which they 
 come. The science of eugenics aims at ends which should 
 encourage all thoughtful young persons so to live that they 
 will keep strong and healthy. 
 
 Kinds of muscles. Muscular tissue occurs in nearly every 
 organ. It helps to form the walls of the blood vessels, and 
 assists in the circulation of the blood ; the eyeballs are moved 
 by six sets of muscles ; the act of swallowing is performed 
 by muscular contraction in the esophagus ; the contrac- 
 tion of the muscles in the walls of the stomach produces the 
 motion by which the food is mixed ; in the intestines the 
 muscles keep the partly digested food in motion ; the muscles 
 in the limbs enable us to move and work ; the heart is chiefly 
 muscle ; the muscles in the chest and trunk enable us to 
 breathe ; those in the larynx are used in talking. 
 
The Muscles as the Motor Machinery of the Body in 
 
 Muscles Have been divided into two classes, voluntary 
 and involuntary. The first class is under the control of the 
 will, either at all times or part of the time; the second is 
 never under the control of the will ; their work goes on quite 
 independently of the will and even during sleep. Can you 
 assign to their proper classes the 
 muscles named in the preceding 
 paragraph ? 
 
 Voluntary (striated) muscles. 
 It is to be remembered that a 
 muscle is made up of cells which 
 are specialized to perform the 
 function of contracting. For the 
 carrying out of this purpose, they 
 have developed fibers within their 
 protoplasm. The contraction of a 
 muscle is caused by the contrac- 
 tion of the individual fibers which 
 compose it. Each fiber shortens in 
 length and becomes proportionally 
 thicker ; the sum total of the con- 
 tractions of these fibers taking 
 place at the same time makes up 
 the contraction of the whole muscle. 
 The number of fibers lying side by 
 
 ., , , xu xi i / xi FlG - 79. A portion of 
 
 Side determines the thickness of the three striated muscle fibers, 
 
 muscle, and the amount Of Strength moderately magnified. Show- 
 
 vu u- u -4. u-i ing the capillary vessels 
 
 with which it can contract; while (dark). 
 
 the number of fibers lying end to 
 
 end determines the amount of shortening or contraction of 
 
 which the muscle is capable. When the muscle is habitually 
 
 used, it becomes larger, finer, darker, and stronger. 
 
 Voluntary and involuntary muscles are not constructed 
 exactly alike. Examined under the microscope, each fiber 
 of a voluntary muscle shows bright bands alternating with 
 
ii2 Healthful Living 
 
 dark bands, running across it (Fig. 79). These bands give 
 the whole muscle a striated or striped appearance under 
 the microscope, and this kind is, therefore, called striated 
 muscle. The fibers are bound together by connective 
 tissue into bundles called fascicles and these again into 
 larger bundles. The connective tissue surrounding the 
 bundles can be plainly seen in chipped beef, also in raw or 
 boiled beef. The voluntary muscles are darker red than 
 the involuntary. Lean meat is made up of these muscles. 
 They are near the surface, but their outlines under the skin 
 are obscured to a greater or less degree in different persons, 
 according to the thickness of the layer of fat between the 
 muscles and the skin. These muscles are usually attached 
 to bones. They contract quickly, while the involuntary 
 muscles contract slowly. 
 
 Involuntary muscles (non-striated, smooth). Involuntary 
 muscles are found in the walls of the alimentary canal, the 
 
 bladder, the esophagus, 
 and several other organs; 
 all such muscles are com- 
 posed of fibers which are 
 not striated, and are, 
 therefore, called plain 
 muscle fibers. A striated 
 
 FIG. 80. Fibers of non-striated 
 
 muscles, or involuntary muscles. fiber is about One inch in 
 
 length and -g-J^ of an inch 
 
 in thickness and is shaped somewhat like a cylinder; it 
 possesses several nuclei. A non-striated muscle fiber is not 
 more than ^^ of an inch in length, has the form of a very 
 slender spindle, and contains one nucleus (Fig. 80). The 
 fibers interlace and are held together by fine connective 
 tissue. 
 
 Cardiac muscular tissue. Cardiac* muscular tissue, 'of 
 which the heart consists, differs from both striated and plain 
 muscular tissue (Fig. 81). Its fibers possess one nucleus, 
 
The Muscles as the Motor Machinery of the Body 113 
 
 FIG. 81. Two 
 
 like plain fibers ; they are not spindle-shaped and narrow, 
 however, but broader and cylindrical. They are, more- 
 over, faintly cross-striated by light and dark 
 bands. We may say, therefore, that al- 
 though the heart is in every respect an in- 
 voluntary muscle, it has more resemblance 
 to striated than to plain muscles. The 
 many muscles used in breathing are at 
 times voluntary, and at other times in- 
 voluntary ; but they are all striated muscles 
 with the usual structure. 
 
 Voluntary and involuntary muscles com- 
 pared. Compare the voluntary and in- 
 voluntary muscles by 
 
 Writing in two Col- cardiac muscle fi- 
 
 umns headed, Volun- ^ ne "j junction 
 
 tary Muscles and between the two 
 
 InvoluntaryMuscles, ^ s ing \ ^Sar 
 
 the facts concerning process of another 
 
 their Control, Struc- el1 ( ma g nified 40 
 
 diameters). 
 
 ture, Color, Position 
 in Body, Attachment, Rate of Con- 
 traction, Number of Nuclei, Length 
 of Fibers, Breadth of Fibers, Shape 
 of Fibers. (Place these titles in a 
 third column.) 
 
 The attachment of muscles. The 
 involuntary muscles are usually found 
 in the wall of organs that have cavi- 
 ties. Thev are sometimes called the 
 
 in tendon (6) . Many other visceral muscles because the internal 
 
 Sn^ ***** * *** Or g anS are CalM the V*' The 
 
 quicker, stronger-acting voluntary 
 
 muscles are called the skeletal muscles because nearly all of 
 them are attached to bones. There are about five hundred 
 
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 voluntary muscles. By studying the figures you will notice 
 that the middle portion of these muscles is usually large and 
 full, and that the muscles taper to small cords at the ends 
 (Fig. 82). The muscles of the calf move the foot, and the 
 muscles of the forearm move the hand. If the full round 
 muscles extended down over the wrists and ankles, it would 
 make these as large around as the forearm or calf, and the 
 wrists and ankles would be very clumsy and awkward. It 
 is found that the connective tissue which binds the fibers of a 
 muscle into bundles and forms sheaths for the bundles, extends 
 beyond the muscular tissue and unites to form a dense, in- 
 elastic, glistening white cord called a tendon. The fibers 
 are very closely packed together and make a very strong 
 cord. One no thicker than a lead pencil is strong enough 
 to support twice the weight of the body. A tendon contains 
 no nerves and very few blood vessels. Some muscles have a 
 tendon at only one end ; some have no tendon but are at- 
 tached directly to bones. 
 Find muscles without 
 tendons by studying the 
 figures. The cordlike 
 nature of tendons can 
 be ascertained by feel- 
 ing the tendons under 
 the knees, called ham- 
 strings, or the tendons 
 in the angle of the 
 elbow. 
 
 How muscles and 
 bones cooperate. 
 When you grasp a heavy 
 weight in the hand and 
 lift it by bending the 
 
 elbow, where is the muscle that does the work? You will 
 easily find it in the upper arm. This muscle is called the 
 
 FIG. 83. Diagram to show the action 
 of the biceps muscle of the arm. The two 
 tendons by which the muscle is attached to 
 the scapula are seen at s ; r, the point of 
 attachment of the muscle to the radius; 
 e, the elbow joint ; h, the weight of the 
 hand. 
 
The Muscles as the Motor Machinery of the Body 115 
 
 biceps because it is attached to the shoulder blade above by 
 two tendons. The lower arm acts as a lever * with the ful- 
 crum,* or fixed point of the lever, at the elbow (Fig. 83). It 
 is easy to see that a slight contrac- 
 tion of the biceps muscle will move 
 the weight a greater distance than is 
 accounted for by the shortening 
 caused by the actual contraction of 
 the muscle. This is what the bones 
 usually accomplish for the muscles ; 
 they change a slow, short, inade- 
 quate movement into a long, swift 
 movement. While the muscle con- 
 tracts an inch, the bone may move 
 a foot. The bones thus add greatly to the range and rate 
 of motion. 
 
 Figures 84, 85 and 86 show the three orders of levers. In the 
 lever of the first order, the fulcrum (F) is between the power 
 (P) and the weight (W). In the lever of the second order 
 the weight is between the other two, and in the lever of the 
 
 Power 
 
 FIG. 84. Tapping floor 
 with toe. Lever of first 
 order. 
 
 Fulcrum 
 
 Weight 
 
 FIG. 85. Raising weight 
 of body upon ankle. Lever 
 of second order. 
 
 Fulcrum 
 
 FIG. 86. Raising a 
 weight upon toes. Lever 
 of third order. 
 
 third order the power is between the others. In Figure 83 
 the biceps muscle acts on the radius and ulna fastened to- 
 gether as one, turning at the elbow as a fulcrum ; the weight 
 to be lifted is in the hand. This is evidently a lever of the 
 
n6 
 
 Healthful Living 
 
 third order with the power between the other points. In 
 this case it takes a force in the muscle equal to about six 
 pounds to raise one pound in the hand. 
 
 Figure 87 shows how the muscles may act upon the bones 
 as levers to prevent the bones from turning upon the joints 
 
 FIG. 87. Diagram 
 of the muscles that 
 keep the body erect. 
 
 stoid 
 
 FIG. 88. Muscles of head and 
 neck. Find the following muscles : 
 Chewing muscles ; scalp muscles ; 
 bowing muscle of one side ; muscle 
 that holds head erect (upper part of 
 trapezius at back of neck) ; muscle 
 that squints the eye ; muscle that 
 pouts the lips ; muscle that broadens 
 the mouth in smiling ; muscle that 
 raises corners of mouth ; muscle that 
 draws down corner of mouth. 
 
 as fulcrums; thus the body is held erect. Where are the 
 muscles located that keep the body from falling or bending 
 forward? From falling backward? Which of the two sets 
 is in front? What kind of lever is illustrated by the head 
 tilted upon the first vertebra? 
 
The Muscles as the Motor Machinery of the Body 117 
 
 Names and positions of muscles. A few of the important 
 muscles are here mentioned : The scalp muscle (Fig. 88) 
 passes over the top of the head ; it raises the skin over the 
 eyes, and (in some persons) moves the scalp. The two pairs 
 of chewing muscles are the temporal * and masseter * (Fig. 88) . 
 You can feel the temporal muscle swell and harden if you 
 
 Trapes/us 
 
 Jtoid 
 
 Latissimus 
 
 FIG. 89. Principal muscles of the back. Trapezius draws shoulder 
 and head back ; deltoid raises whole arm ; latissimus, climbing muscle ; 
 obliquus internus and obliquus externus draw abdominal wall in and force 
 abdominal contents against the diaphragm, thus expelling air from lungs. 
 
 place your finger on the temple and close your mouth forcibly. 
 In the same manner you may feel the contraction of the 
 masseter by placing the fingers just below the cheek bone. 
 The muscle used in bowing passes obliquely down on the 
 side of the neck to the collar bone (Fig. 88). It can be 
 felt as a thick band ; when the head is turned to one side, it 
 stands out as a ridge. When one of the two acts alone, it 
 turns the face so as to look to the other side. When both 
 act, they bow the head. The deltoid * (Fig. 89), or shoulder 
 
n8 Healthful Living 
 
 cap muscle, raises the whole arm outward and upward from 
 the side. Can you locate it by the feeling of fatigue after 
 raising the arm twenty times? The biceps can be seen and 
 felt contracting on the front of the arm when bent at the 
 elbow. The triceps* is on the opposite side of the arm and 
 
 Extensors of the Hand 
 flexors oftheffand 
 
 Trrceps 
 
 -PectoraNs- Maic 
 De/toid- ~ "" 
 
 Serratus Afatjnus- 
 
 -Rectus Abdominal/ s 
 
 Pectus Femorfs - 
 
 \HPBVifiS3Bii 
 
 -Vastus Externus 
 
 Hr 
 
 Tibiatis Anticus' 
 
 //m\ 
 
 -Extensors of the Toes 
 FIG. 90. Full-figure muscles (front) . 
 
 straightens the elbow (Fig. 92). Which is used in striking 
 a blow, the biceps or the triceps ? 
 
 The sartorius* (tailor) muscle (Fig. 90) is nearly two feet 
 long and is the longest muscle in the body ; it passes from the 
 outer side of the hip bone to the inner side of the leg below 
 
The Muscles as the Motor Machinery of the Body 119 
 
 the knee, and is used in crossing the leg; because of the 
 position assumed by a tailor at work it is named the tailor's 
 muscle. The gastrocnemius* is a thick muscle in the calf 
 of the leg, which raises the heel (Fig. 91). When is it used? 
 It is attached to the heel by the largest tendon in the body, 
 
 Extensors of 
 (he Hand 
 
 <Trapezhj$ 
 
 ^MiHBK^^ff^l BO / 
 
 Triceps 
 
 Dettoid 
 
 Latissimus Dorsr 
 
 Vastus Externus 
 
 TendoAchilfis 
 
 FIG. 91. Full-figure muscles (rear). 
 
 called the " tendon of Achilles." Ask the teacher why it is 
 so called, or read the story of Achilles. 
 
 The trapezius* (four-sided) (Figs. 89 and 91) is a large 
 muscle covering the back between the shoulders. It draws 
 the shoulders back and holds up the head. Can you find 
 
I2O 
 
 Healthful Living 
 
 the climbing muscle (Fig. 89), or the muscle that draws 
 the arm backward and downward (latissimus or broadest) ? 
 When a person hangs by the hands, it helps to raise the body. 
 It is a large spread-out muscle extending from the humerus 
 to the vertebral column. 
 
 There is a great fan-shaped muscle called the pectoralis 
 (Fig. 92), which attaches the arm to the front wall of the 
 
 Tr/cepi 
 
 Sterno-M&stofd 
 Trspezfus 
 
 JDe/tofd 
 
 External 
 Ob/ique 
 
 FIG. 92. Superficial view of muscles of upper part of trunk, 
 from the front (Allen Thomson). 
 
 thorax. Muscles are arranged in opposing sets. Flexors 
 oppose extensors, abductors act against adductors. Two 
 muscles with opposite action or function are said to be an- 
 tagonists.* When antagonistic muscles work together in 
 harmony, then the movement is graceful. Awkwardness 
 results from too strong contraction of one of the antagonistic 
 groups. In learning a new movement, more muscles than 
 are necessary are used at first. The beginner in skating, for 
 
The Muscles as the Motor Machinery of the Body 121 
 
 < 
 
 example, should not try too hard, should not be too tense, 
 and the coordination will come quicker. 
 
 Muscles are named from their shape, as deltoid (like the 
 Greek letter delta, A) ; their location, as tibialis (near ,the 
 tibia) ; their action, as flexors ; their manner of attachment, 
 as triceps (three-headed). 
 
 GLOSSARY 
 
 Antagonist. In muscles, a muscle that acts counter to another 
 
 muscle. 
 Cardiac muscle. The muscle of the heart. The word comes 
 
 from the Greek word kardia meaning heart. 
 Deltoid. The muscle that covers the point of the shoulder. So 
 
 called because of its shape. It is triangular like the Greek 
 
 letter delta. 
 Eugenics. The science of improving the human race. Term 
 
 first used by Sir Francis Galton. 
 Fulcrum. The support on which a lever rests and by means of 
 
 which it obtains its power. 
 Gastrocnemius. A large muscle of the leg so called because of 
 
 its large belly (from Greek gaster} and its situation on the 
 
 lower leg (from Greek knemis, meaning greave, or kneme, 
 
 meaning lower leg). 
 Heredity. The tendency shown by an organism to develop in 
 
 the likeness of its forbear. 
 Lever. Usually a straight bar turning on a fixed point as the 
 
 fulcrum and serving to produce a pressure from the power 
 
 moving the lever to the weight or resistance to be moved. 
 Masseter. A muscle of the jaw used in chewing. So called 
 
 because of its function, from the Greek word, maseter, a. chew. 
 Sartorius. A long muscle of the thigh ; so called from its use in 
 
 crossing the legs, as of tailors. Sartor meaning a patcher, 
 
 hence a tailor. 
 Temporal. A muscle that is located at the side of the head near 
 
 the temple. 
 Triceps. A muscle at the back of the upper arm. It has three 
 
 heads. 
 Trapezius. A large flat muscle of the back shaped like a trapezoid 
 
 when the two muscles are viewed together. 
 
CHAPTER VIII 
 
 THE MUSCLES IN ACTION AND THE HYGIENE OF 
 EXERCISE 
 
 I. The Neuro-muscular Mechanism. 
 
 Response of the muscle to the nerve stimulus 
 Coordination of muscles 
 II. Muscular Energy. 
 Production 
 Expenditure 
 
 III. Muscular Tone. 
 
 IV. Muscular Activity and Fatigue. 
 
 V. The Effect of Stimulants and Narcotics on Muscular Action. 
 
 VI. The Effect of Exercise on Growth. 
 
 VII. The Relation of Exercise to Health. 
 
 VIII. Forms of Exercise. 
 
 IX. Over-development of the Muscles. 
 
 The neuro-muscular mechanism. If the nerve to the 
 muscle is severed, the muscle cannot be contracted no 
 matter how hard we try. Is a muscle and its nerve a unit ? 
 This unity is sometimes called the neuro-muscular mech- 
 anism. If this mechanism is called psycho-motor, * to what 
 does it refer? Does neuro-muscular refer to structure? 
 
 Response of the muscle to the nerve stimulus. When a 
 muscle cell receives a stimulus from its nerve, it changes its 
 shape by growing shorter; it does not increase in size. 
 When a boy shows his muscle by flexing his elbow, the biceps 
 muscle shortens and becomes thicker in one part, but the 
 entire muscle does not take up more room than it did when 
 in a relaxed condition. 
 
 122 
 
The Muscles in Action and the Hygiene of Exercise 123 
 
 Coordination* of muscles. Would you like to see two 
 persons try to thread a needle, one holding the thread and 
 the other the needle? Would they succeed well? Or in 
 so simple a matter as the use of the knife and fork in eating, 
 could it be easily done if one holds the piece of meat with the 
 fork while the other tries to cut it ? Why is it that the right 
 hands of two persons cannot work so well together as the 
 right and left hands of one person? It is because of the 
 nervous connection between the hands of the same person, 
 so that one hand knows just what the other is doing. 
 
 Let us think of what takes place in our bodies when we 
 throw a stone at a mark. At the same time we see the 
 mark, hold the stone in the hand, and throw it. In throw- 
 ing a stone, at least a dozen muscles are used. Each one of 
 these must contract at the right time and in the right way, 
 or the stone will miss the mark. Each muscle shortens 
 under the influence of a nerve impulse brought from the 
 brain by a motor nerve. If one muscle shortens an instant 
 too soon, or a little too much, the stone goes to one side. 
 This working together of the muscles by the aid of the nerves 
 is called coordination. Coordination is necessary, even in 
 standing erect. 
 
 Muscular energy. It is well known that the activities 
 upon which life depends involve a continuous expenditure 
 of energy. The beating of the heart, the secretion by glands, 
 the contraction of muscles, the discharge of nerve impulses 
 all expend energy. It is also well known that such activi- 
 ties involve a constant breaking down of chemical compounds. 
 These compounds come from the food eaten and they may 
 be used at once or after being stored in the body. These two 
 facts then are closely associated : 
 
 1. The constan breaking down of chemical compounds. 
 
 2. The continuous expenditure of energy. 
 Production. But just how is energy formed in the body? 
 
 It is formed by the chemical action of the compounds which 
 
124 Healthful Living 
 
 come from the food we eat. All the energy that is available 
 in the muscle for contraction has its origin in the chemical 
 changes that follow after the nerve impulse has come to the 
 muscle. We shall understand better what energy is when 
 we remember that heat and energy are the same. The 
 physicist says that heat is the lowest form of energy. The 
 chemist can show that chemical combinations liberate heat, 
 which tends to express itself as energy. Consider the 
 laboratory experiment on page 56. So in the body, the 
 chemical union of food elements produces energy which 
 appears in the different cells in the form which is of use to 
 that cell. The voltaic cell is similar to the nerve cell and 
 the electric current produced is similar to the nerve impulse 
 of the nerve cell. The heat produced in the test tube by 
 the action of the zinc and sulphuric acid represents the heat 
 produced in the muscle after the chemical action of the food 
 compounds. What starts the chemical action of the food 
 elements in the muscle ? 
 
 The conversion of food into heat and energy is going 
 on in the body all the time so long as life exists. It is less 
 in sleep and more during activity. It is maintained by the 
 food eaten daily. Is this an argument for nutritious foods, 
 properly cooked and carefully eaten? If no food is eaten, 
 it goes on just the same and uses up the cells of the body. 
 How can weight be reduced? More energy is required for 
 stout than for thin persons ; more in cold weather than in 
 hot, more in fever than in health. A growing child requires 
 more energy in relation to its weight than an adult. If a 
 child weighs 60 pounds and a man weighs 150 pounds, which 
 will require more energy? If the child needs 1920 units 
 of heat and if the man needs 2850 units of heat, which re- 
 quires more in relation to its weight? The heat energy 
 necessary for muscular contraction may be obtained from any 
 of the three foodstuffs carbohydrates,* fats,* or proteins.* 
 It is believed that the carbohydrates afford the most favor- 
 
The Muscles in Action and the Hygiene of Exercise 125 
 
 able source of supply and they will be used first, if present 
 in sufficient amount. The blood in the arteries going to the 
 muscles contains more sugar than the blood in the veins 
 coming from the muscles. Would sweet chocolate be a good 
 food to carry on a long tramp ? 
 
 Expenditure. It is found that the use of many small 
 muscles is much more exhausting than the use of a few larger 
 ones. This is on account of the nerve energy consumed. 
 A drummer beating a big bass drum may do more muscular 
 work than one who plays a tune softly on the piano, but the 
 piano playing exhausts the performer much sooner. This 
 is because the movements of the wrist and fingers employ 
 thirty muscles and a great number of nerves. The striking 
 of the keys with the ends of the fingers, where some of the 
 most sensitive nerves of the body terminate, may have some 
 effect also, and may help to explain why so many persons, 
 especially girls, who take little other exercise, have become 
 nervous wrecks from piano playing. Continued typewriting 
 and penmanship are exhausting, but typewriting gives vari- 
 ety of motion, while handwriting calls for a monotonous use 
 of the same muscles. 
 
 The fact that the muscles are arranged in pairs as antago- 
 nists of each other may have a calamitous effect in the case 
 of persons with ill-regulated nervous system. Such persons 
 on account of anxiety or worry, doubt, or over-active desire, 
 keep their muscles drawn tense, the antagonists pulling 
 against each other, and after a while they lose the power of 
 relaxing their muscles. They wear anxious expressions, be- 
 cause the muscles of the face are never relaxed or in repose. 
 Their movements are nervous and jerky instead of graceful 
 and easy. Their breathing is not deep and natural, and 
 their voices, therefore, are not even and steady. They 
 cannot be perfectly still, but chew gum or a pencil, rock the 
 chair, bite their finger nails, or claw their knuckles. Have 
 you any friends who are handicapped by this condition of 
 
126 
 
 Healthful Living 
 
 over-tension? When such people listen to a sermon, their 
 backs get tired because they cannot relax comfortably in 
 the seat. When they lie down, they try to hold the body 
 on the bed, and instead of relaxing the muscles of the neck, 
 try to hold the head on the shoulders. 
 
 Over-tension is common to adults in cold climates, but 
 it is also known in warm climates. A graceful person, like 
 a child, uses just the muscles necessary for any act, and no 
 more. Ease of manner, as well as health, makes important 
 the correction of conditions to which all hurrying, am- 
 | v bitious persons are liable in an 
 
 age of keen competition and of 
 ambition for learning and dis- 
 tinction. 
 
 Muscular tone. That the 
 muscles may be always ready for 
 use, they must not be entirely 
 soft and flabby, but should be 
 under a condition of very slight 
 contraction, called tone (Fig. 93). 
 We find that the muscular walls 
 of the blood vessels possess tone. 
 It is this condition of slight con- 
 traction which causes a wound in 
 the flesh to gape open. If a ten- 
 don is cut, the muscle shortens 
 on account of its tone. If the 
 nerve going to the muscle is cut, 
 FIG. 93 - Diagram of good t h e muscle lengthens a little, that 
 
 posture showing well-developed . . , 
 
 rectusabdominis muscle in tonic is, it relaxes, showing that there 
 
 Sternum 
 
 Os Pubis 
 
 contraction ; dotted line show- 
 ing poor posture with relaxed 
 and flabby abdominal wall. 
 
 mugt b e f a j nt but constant im- 
 . . . , 
 
 pulses coming through the nerve 
 to keep the muscle in tone. When 
 
 one is asleep, the body does not lie perf ectly straight, but 
 the joints are slightly bent to allow relaxation. 
 
The Muscles in Action and the Hygiene of Exercise 127 
 
 Muscular activity and fatigue. If we suspend a frog's 
 muscle from a muscle clamp, and attach the tendon to a 
 writing lever, on stimulation of the muscle by an electric 
 current we can record the contraction that results. In a 
 series of contractions (Fig. 27) of a fresh muscle, there will 
 be seen a gradual increase in height of the contractions 
 (called, Die Treppe the staircase} until the maximum is 
 reached (Fig. 27) ; and presently the height will decrease. 
 The height will gradually fall until no contraction at all 
 occurs, no matter how strong the stimulus. The increase 
 in power at first is due to the increased irritability of the 
 muscle cells brought on by the presence of chemical sub- 
 stances formed in the muscle during the production of energy. 
 These are known as fatigue substances. They are forms of 
 chemical compounds which represent the waste material 
 left after the combustion in the muscle, and in this re- 
 spect resemble the ashes left in the furnace. After these 
 fatigue substances increase in amount, the irritability of 
 the muscle is lessened, so that there is a decrease in the 
 height of the contractions (Fig. 27). What purpose do 
 warming-up exercises have in relation- to performing an 
 athletic feat? 
 
 When fat or carbohydrate is used as the source of energy 
 for muscular contractions, the waste products are carbon 
 dioxide, mono-potassium phosphate, and lactic acid. When 
 proteins* are used as energy, the waste products from these 
 are in the forms of urea uric acid, creatin, and others. Now, 
 all these substances interfere with the working of the muscle. 
 By getting into the blood stream and by being carried to 
 other parts of the body, the effects from a local activity 
 may be felt all over the body. Fatigue of one part lowers 
 the efficiency of the rest of the body. These fatigue products 
 are removed chiefly by the kidneys and lungs. Rest, sleep, 
 and food to restore the chemical forces used are necessary 
 for complete recuperation of the body after a fatiguing task. 
 
128 
 
 Healthful Living 
 
 Sleeping is the best way of resting. What are the other 
 lines in this quotation? 
 
 " Sleep that knits up the ravell'd sleave of care." 
 Who wrote these lines? Did he know much about physi- 
 ology? Is such knowledge of value to a poet and a writer? 
 Name the professions in which knowledge of physiology is 
 absolutely necessary. Is it of value to a father?' To a 
 mother ? 
 
 In Figure 94 two graphic* representations of muscular 
 contractions are shown. In A the contractions at the be- 
 
 FIG. 94. The effect of rest on muscular contractions. A shows the 
 contractions of a fresh muscle. B shows the contractions of the same 
 muscle with a rest of five minutes after doing the work shown in A. 
 
 ginning are higher than those in B. Between A and B there 
 was a rest of 5 minutes. It is to be noticed that the con- 
 tractions in B at the beginning are higher than those at the 
 ending of A, but not as high as those at the beginning of A ; 
 in addition it is seen that fatigue comes quicker in B than in 
 A. These contractions are of the muscle that abducts the 
 index finger. 
 
 The effects of stimulants and narcotics * on muscular ac- 
 tion. The weaker forms of alcohol, such as ale and beer, 
 cause a change into fat of much of the albumin* in muscle 
 cells, thus bringing about a bloated and flabby condition, 
 called fatty degeneration.* It may even reach the heart, 
 
The Muscles in Action and the Hygiene of Exercise 129 
 
 causing a dangerous disease called fatty degeneration of 
 the heart. There are other causes of this condition. If 
 an athlete who has developed enormous muscles suddenly 
 ceases to train, his muscles may undergo fatty degeneration. 
 Through the narcotic or deadening effect of alcohol, the 
 nerves become less sensitive, and fatigue is not so readily 
 perceived. This unawareness of the real bodily condition 
 gives the drinker a deceptive feeling of strength and power. 
 
 It has been found that two hours after taking two ounces 
 of whisky mixed with eight ounces of water, the muscular 
 strength of the man experimented on was reduced one third. 
 This means that a lifting power of three hundred pounds was 
 reduced to two hundred pounds. An old drunkard usually 
 has a dragging gait and trembling hands. Coffee, which is a 
 stimulant, sometimes causes a twitching of the eyelids ; this 
 is a sign that the body is being irritated. 
 
 The effect of exercise on growth. Exercise has a stimu- 
 lating effect upon growth. This effect has been recorded 
 many times by scientific observers. Henry G. Beyer, M.D., 
 reported observations on the growth of 188 naval cadets who 
 took special systematic exercise, and compared it with the 
 usual growth of cadets of the same age. 
 
 There was an increase in height of more than one inch 
 above that which took place without the special exercise. 
 
 The increase in strength was five times as much as the 
 normal increase. 
 
 There was an increase in weight of 77 pounds in the four 
 years during which the observations were made. 
 
 There was an increase in lung capacity * of 1.72 liters. 
 
 The growth of the body in height and weight is determined 
 partly by the influence of heredity and partly by the kind 
 of care the body receives. Height is determined largely by 
 heredity, and weight largely by environment. The following 
 table by Dr. Holt shows the weight, height, and circumfer- 
 ence of the head and chest from birth to the sixteenth year : 
 
130 
 
 Healthful Living 
 
 AGE 
 
 WEIGHT IN 
 POUNDS 
 
 HEIGHT IN 
 INCHES 
 
 CHEST IN 
 INCHES 
 
 HEAD IN 
 INCHES 
 
 Birth 
 
 Boys 
 
 7.55 
 
 20.6 
 
 13.4 
 
 13.9 
 
 Birth 
 
 Girls 
 
 7.16 
 
 20.5 
 
 13.0 
 
 13.5 
 
 6 months 
 
 Boys 
 
 16.0 
 
 25.4 
 
 16.5 
 
 17.0 
 
 6 months 
 
 Girls 
 
 15.5 
 
 25.0 
 
 16.1 
 
 16.6 
 
 12 months 
 
 Boys 
 
 20.5 
 
 29.0 
 
 18.0 
 
 18.0 
 
 12 months 
 
 Girls 
 
 19.8 
 
 28.7 
 
 17.4 
 
 17.6 
 
 18 months 
 
 Boys 
 
 22.8 
 
 30.0 
 
 18.5 
 
 18.5 
 
 18 months 
 
 Girls 
 
 22.0 
 
 29.7 
 
 18.0 
 
 18.0 
 
 2 years 
 
 Boys 
 
 26.5 
 
 32.5 
 
 19.8 
 
 18.9 
 
 2 years 
 
 Girls 
 
 25.5 
 
 32.5 
 
 18.5 
 
 18.6 
 
 3 years 
 
 Boys 
 
 31.2 
 
 35.0 
 
 20.1 
 
 19.3 
 
 3 years 
 
 Girls 
 
 30.0 
 
 35.0 
 
 19.0 
 
 19.0 
 
 4 years 
 
 Boys 
 
 35.0 
 
 38.0 
 
 20.7 
 
 19.7 
 
 4 years 
 
 Girls 
 
 34.0 
 
 38.0 
 
 20.5 
 
 19.5 
 
 5 years 
 
 Boys 
 
 41.2 
 
 41.7 
 
 21.5 
 
 20.5 
 
 5 years 
 
 Girls 
 
 39.8 
 
 41.4 
 
 21.0 
 
 20.2 
 
 6 years 
 
 Boys 
 
 45.1 
 
 44.1 
 
 23.2 
 
 
 6 years 
 
 Girls 
 
 43.8 
 
 43.6 
 
 22.8 
 
 
 7 years 
 
 Boys 
 
 49.5 
 
 46.2 
 
 23.7 
 
 
 7 years 
 
 Girls 
 
 48.0 
 
 45.9 
 
 23.3 
 
 
 8 years 
 
 Boys 
 
 54.5 
 
 48.2 
 
 24.4 
 
 
 8 years 
 
 Girls 
 
 52.9 
 
 48.0 
 
 23.8 
 
 
 9 years 
 
 Boys 
 
 60.3 
 
 50.1 
 
 25.1 
 
 
 9 years 
 
 Girls 
 
 57.5 
 
 49.6 
 
 24.5 
 
 
 10 years 
 
 Boys 
 
 66.6 
 
 52.2 
 
 25.8 
 
 21.0 
 
 10 years 
 
 Girls 
 
 64.1 
 
 51.8 
 
 24.7 
 
 20.7 
 
 11 years 
 
 Boys 
 
 72.4 
 
 54.0 
 
 26.4 
 
 
 11 years 
 
 Girls 
 
 70.5 
 
 53.8 
 
 25.8 
 
 
 12 years 
 
 Boys 
 
 79.8 
 
 55.8 
 
 27.0 
 
 
 12 years 
 
 Girls 
 
 81.5 
 
 55.1 
 
 26.8 
 
 
 13 years 
 
 Boys 
 
 88.3 
 
 58.2 
 
 27.7 
 
 
 13 years 
 
 Girls 
 
 91.2 
 
 57.7 
 
 28.0 
 
 
 14 years 
 
 Boys 
 
 99.3 
 
 61.0 
 
 28.8 
 
 
 14 years 
 
 Girls 
 
 100.3 
 
 60.3 
 
 29.2 
 
 
 15 years 
 
 Boys 
 
 110.8 
 
 63.0 
 
 30.0 
 
 21.8 
 
 15 years 
 
 Girls 
 
 106.4 
 
 61.4 
 
 30.0 
 
 21.5 
 
 16 years 
 
 Boys 
 
 123.7 
 
 65.6 
 
 31.2 
 
 
 16 years 
 
 Girls 
 
 118.0 
 
 61.7 
 
 30.8 
 
 
 The relation of exercise to health. It was learned on 
 page 6 that the muscular system developed to make loco- 
 
The Muscles in Action and the Hygiene of Exercise 131 
 
 motion possible. Animals of every species are dependent 
 upon movement for obtaining the necessities of life. The 
 important thing for us to remember is that for innu- 
 merable years muscles have been a part of the human body 
 as constructed to-day. We have inherited, therefore, a 
 muscular system, and with that system we have inherited 
 the need for activity. Young people are usually very active, 
 but too often, after school days, they lead physically inactive 
 lives in office, store, or home. Some people think they can 
 maintain health and strength by a two-minute drill in their 
 room before retiring. Health cannot be obtained or main- 
 tained by such condensed pill-like measures. There must 
 be outdoor life and outdoor exercise if the human body is 
 to keep its inheritance. The boy and girl in school and 
 college should learn to enjoy and to become proficient in 
 some game or sport, so that in adult life this activity may 
 be followed. Too often in adult life men and women are 
 so weak physically that they do not enjoy exercise. Such 
 condition of the body is unfavorable to the maintenance of 
 health, to say nothing of the resulting effect of bad disposi- 
 tion, ill temper, and nervousness. Walking for some people 
 is a serious task. If there is proper training throughout 
 life, walking may be mora than a means of progression 
 it may be a real joy. 
 
 There are those who go to the other extreme as regards ex- 
 ercise. They strive constantly for records in athletic events. 
 They over-develop their hearts, and serious harm often re- 
 sults. The danger for the nation, however, is not from ath- 
 letics, but rather from a lack of all forms of physical educa- 
 tion. It is to be remembered, therefore, that exercise is 
 important, not only for the health of the individual, but also 
 for the strength and vigor of the race. We have received 
 our bodies as an inheritance from an ancestry that lived 
 largely an outdoor life. To-day there is a great concen- 
 tration of population in cities, and it is necessary that city 
 
132 
 
 Healthful Living 
 
 folk exercise out-of-doors to preserve the inheritance that 
 has been received. 
 
 Forms of exercise. It is best to choose a form of exercise 
 that you enjoy. Exercise that is performed as a task is a 
 drain on the nervous system; its results are questionable, 
 and sooner or later it is given up in disgust. Too often the 
 
 FIG. 95. Which is the better forced exercise or games? 
 
 expression is heard, " I hate gymnasium work." This 
 comes because the exercise is not interesting and in no way 
 appeals to the instincts of the child. Most games and 
 sports are excellent forms of exercise (Fig. 95) . 
 
 The games that are most interesting are those that have 
 the " give-and-take " principle present. Such games give 
 to the player an opportunity and in turn take a chance. 
 
The Muscles in Action and the Hygiene of Exercise 133 
 
 This is illustrated in such a game as baseball. The pitcher 
 gives the batter a chance at the ball and the batter takes 
 the opportunity offered, or refuses it. Such games as swing- 
 ing are less interesting because they have not this principle 
 present. In which of the following games is this " give-and- 
 take " element present and in which is it most prominent? 
 
 Tennis is a splendid game. It may be played in youth 
 and in adult life by both sexes. It has a fine play element 
 and gives good physiological results on the body. 
 
 Swimming is a very desirable form of exercise. Every 
 city should have swimming pools, so that the sport may be 
 practiced in winter as well as in summer. Sea bathing is 
 very beneficial. To what is the beneficial effect chiefly due ? 
 
 FIG. 96. Cabin built by scouts for use as Troop Heauquarters. 
 
 Camping. The outdoor activities of the Boy Scouts, 
 Girl Scouts, Camp Fire Girls, and other camping organiza- 
 tions afford a fine opportunity for outdoor exercise (Fig. 96). 
 
134 Healthful Living 
 
 The activities out-of-doors are especially beneficial upon 
 
 \ the blood. For several years the author has kept a record 
 
 \of the increase in the iron content of the blood in girls in a 
 
 jsummer camp. After six weeks of camping at Camp Mesa- 
 
 cosa the average increase in hemoglobin has been 16 per 
 
 cent. Some girls gained as much as 22 per cent. Good 
 
 food, exercise, sleep and the sun's rays are the important 
 
 factors in promoting this improved blood condition. 
 
 Walking and running, if not done too leisurely, are good 
 exercises. Americans probably make too great a use of 
 street cars. English women are noted as walkers, and in 
 the cooler parts of the United States this custom would be 
 equally effective in preventing nervousness and weakness 
 among women. Walking requires proper shoes. 
 
 Running is a still better exercise, but it should be begun 
 gradually and with caution, so as to give heart and lungs 
 opportunity to become strong enough to sustain the in- 
 creased effort required of them. One should never run 
 with the mouth open. One should keep in such physical 
 condition as at all times to be able to run swiftly and effi- 
 ciently. Too frequently persons allow themselves to become 
 so unfit that a run for 100 yards is impossible. To keep 
 " fit" is at times difficult ; it is always worth the effort. 
 
 Boxing and wrestling and fencing are good sports, but they 
 are not common because of the skill necessary for their per- 
 formance. They are more liable to produce injury of the 
 participants and so should be well supervised. Boxing has 
 become very popular in the training of the American army 
 for the Great War. It provides not only the general bene- 
 ficial effects of exercise, but the movements are similar in 
 type and quality to the movements used in fighting with the 
 bayonet. Every boy should develop skill in at least one 
 of these three sports. 
 
 The group games such as volley ball, dodge ball, captain 
 ball, and the group relays such as all-up relay, overhead 
 
The Muscles in Action and the Hygiene of Exercise 135 
 
 pass relay, and others are splendid games for the school 
 ground and gymnasium (Fig. 97). The tug-of-war is 
 excellent exercise (Fig. 98). 
 
 FIG. 97. The relay race provides competition and demands cooperation. 
 Notice the starting position of the girl on the right. Girls may learn to 
 run freely as boys do. 
 
 The specialized games, such as baseball, basketball, and foot- 
 ball are admirable during school days, but they are of 
 
 FIG 98. Blind boys in a tug of war. Games and contests out of 
 doors are available for all even the blind. 
 
 little use after school days are over. Such games not only 
 strengthen muscle and nerve but also may develop presence 
 
Healthful Living 
 
 of mind, coolness, fearlessness, self-control, and other fine 
 qualities. Basketball with girls' rules, and indoor base- 
 
 FIG. 99. Hockey requires strength and is valuable for the High 
 School girl. 
 
 ball using the number 12 playground ball, are fine games 
 for girls in high school and college. 
 
 
 FIG. 100. A Morris Dance. Men and boys do some dances better than 
 women and girls. Dances of this type out of doors are not only healthful 
 but also "fun to do." This kind of dancing calls for strength and endurance 
 and may enlist the strongest athlete. 
 
 Hockey is a splendid game for girls. The field should be 
 shortened to 70 yards, because the regulation field makes 
 
The Muscles in Action and the Hygiene of Exercise 137 
 
 too strenuous a game for girls, and, moreover, the shorter 
 field permits more scoring and thus adds to the interest of 
 the game. 
 
 Dancing. The dance at one time was a ritual used 
 in religious ceremonies. Dancing, therefore, really began as 
 a religious cult. To-day there are different forms of danc- 
 
 FIG. 101. Throwing the discus. The group in the background is 
 holding a group baseball throw. 
 
 ing. Folk* dances are the dances of folk people giving ex- 
 pression to their feelings. These are dances, therefore, that 
 are characteristic of the nations, and in this way we must 
 think of the Tarantella of Spain, the Irish Lilt of Ireland 
 and the English Country Dances. ^Esthetic * dancing is an 
 attempt to produce certain graceful forms of movement in 
 dance. Too frequently, it is taught as a series of steps or 
 poses in which there is no thought or emotion. It thus 
 becomes a mere exercise. It should be taught as an art 
 
138 
 
 Healthful Living 
 
 in which all the technique serves as the medium for the self- 
 expression of the dancer. Social dancing is in common use 
 in the United States and eastern Europe. It is exhilarating 
 and restful on account of the music and the rhythm. If it is 
 done finely, in a beautiful way, it is very beneficial. 
 
 Athletic sports for girls need to have standards that are 
 not too difficult 'for the girl athlete. Girls should not try 
 to do the same events in which boys excel. There are, how- 
 
 FIG. 102. Throwing the lariat. This event calls for accurate judgment 
 and good body. 
 
 ever, some athletic events that girls do very well, and two of 
 these are shown in Figures 101, 102. In the figures showing 
 the discus and lariat, notice that the left foot of the athlete 
 is forward and the right arm. This opposite position of the 
 arm and leg is very important in all throwing movements. 
 For example, in throwing a baseball with the right arm, the 
 left foot should be forward. Girls are familiar with this law 
 in dancing, but because of their lack of training in sports 
 
The Muscles in Action and the Hygiene of Exercise 139 
 
 they rarely show the good position of the discus thrower 
 (Fig. 101). Camping with its related activities is very valu- 
 able for girls (Fig. 103). The following health essentials for 
 
 r 
 
 FIG. 103. City girls on a "hike" in the country. Which one of the 
 three girls shows the best posture? 
 
 girls 12 to 14 years old are good rules for all girls. The girl 
 athlete could follow no better training schedule than this 
 one, proposed by Dr. Thomas D. Wood. 
 
 SUGGESTED ESSENTIALS FOR HEALTH OF GIRLS 12 TO 14 YEARS OLD 
 
 1. Sleep. 10| hours in bed each night. 
 
 2. Food. A nutritious diet with special emphasis upon an 
 adequate breakfast. 
 
 3. Play and recreation. At least one hour of out-door ac- 
 tivity each day, during full daylight. 
 
 4. Bathing. A tepid to cool sponge, shower, or quick plunge 
 in the tub daily, before breakfast. 
 
 5. All the out-door air possible, particularly in the sleeping 
 room. 
 
 6. Freedom from worry, hurry, and over-excitement. 
 
 The above schedule may serve with slight alteration as 
 " training rules" for boys. The boy who is interested in 
 athletics and physical efficiency will not use tobacco. More- 
 
140 Healthful Living 
 
 over, he should not spend more than three hours a day in 
 practice. For many of the track sports, a half hour is 
 sufficient. The high school boy is frequently injured in 
 athletics by engaging in too many events in track meets, 
 so that later, in college, he has not the endurance that he 
 needs for sharper competition. 
 
 Over-development of muscles. As important as mus- 
 cular exercise is for sending the blood bounding through the 
 veins and renewing the health of every part, exercise can be 
 overdone. Some athletes develop great heavy muscles 
 which are a burden to the vital organs to support. They 
 do not take care to develop their lungs and breathing powers 
 in proportion. Breathing exercises are often used to over- 
 come the bad effects of inactivity and torpor. This method 
 of getting strength and vigor is wrong. Exercise, vigorous 
 enough to increase the respiration, should be used, and the 
 breathing will care for itself. Those who aim only to de- 
 velop certain muscles, who do nothing but apparatus work 
 or some such specialty, get large muscles but not health and 
 strength of body. Such athletes die young. Among those 
 who have succumbed to consumption may be mentioned 
 Kehoe, the famous club swinger; Dowd, the teacher of 
 physical culture ; " Jap," the wrestler ; Winship, the in- 
 ventor of the health lift ; Kennedy, the strong man ; and 
 Peter Jackson, the pugilist. Complete living with conditions 
 of health and activity for all the organs, without extreme 
 use of any of them, is most conducive to a long and healthful 
 life. 
 
 APPLIED PHYSIOLOGY 
 Exercise I 
 
 1. Does a few minutes' practice in a gymnasium suffice for 
 a day's exercise ? 
 
 2. Is there any relation between the amount of bodily exer- 
 tion necessary for a person's health and the amount of wealth lie 
 possesses ? 
 
The Muscles in Action and the Hygiene of Exercise 141 
 
 3. It is said that an Indian often runs or trots sixty miles per 
 day, and that he rests his muscles without stopping by running for 
 a while chiefly with the hip joint and muscles of the thigh, then 
 with the knee joint and muscles of the upper leg. Can you rest 
 some of the running muscles while running? 
 
 4. Can you relax the chewing muscles so that the lower jaw will 
 swing loosely when the head is shaken ? 
 
 5. Can you relax the muscles of the forearm so that the hand 
 will shake loosely on the wrist and the fingers in their sockets ? 
 
 6. Can you relax the whole arm so that another person can 
 move it as a flexible rope? 
 
 7. Which joints of the limbs lock and refuse to bend further 
 when the limb is straightened? 
 
 8. Which muscles have become useless with most persons, 
 although some can still use them ? 
 
 9. The average man has 60 Ibs. of muscle and 2 Ibs. of brain ; 
 one half of the blood goes through the muscles and one fifth goes 
 through the brain. What inference may you draw as to the kind 
 of life we should lead ? 
 
 10. What are the beneficial effects of exercise upon the func- 
 tions of the skin? 
 
 11. Is a slow formal walk suitable exercise? What exercise 
 do you enjoy most ? Do you practice it ? 
 
 Exercise II 
 
 12. How can we best prove that we have admiration and respect 
 for our wonderful bodies ? 
 
 13. In what part of the skeleton is it most important to keep 
 the muscular walls firm and strong in order to hold the internal 
 organs in position ? 
 
 14. Why should a youth who wishes to excel in athletic con- 
 tests abstain from the use of tobacco ? 
 
 15. How does the fact that if the nerves of one side of the face 
 are paralyzed the face will be drawn toward the other, illustrate 
 muscular tone? 
 
 16. Why does a game of baseball on Saturday afternoon ac- 
 tually rest a tired shop boy? 
 
 17. What movements did you ever see a cat go through for 
 the sake of exercise? 
 
 18. What animals have you ever seen play? Stretch them- 
 selves for exercise ? 
 
142 
 
 Healthful Living 
 
 19. Why do you feel so exhausted after a fright ? 
 
 20. How do you account for the origin of the mental state, 
 which holds in practice if not in theory, that all physical labor 
 is an unmitigated evil ? 
 
 21. Do you know persons who seem to be possessed by what is 
 called " the spirit of jerkiness " ? How could they overcome it? 
 
 22. What is energy? How is it formed? 
 
 LABORATORY EXERCISES 
 
 Experiment 1. To study the contraction of muscle. 
 
 Material! Muscle from a frog, muscle clamp, inductorium 
 (Fig. 187), pincers, acetic acid. 
 Method and observation. 
 
 (a) Arrange the muscle from the frog's leg on a muscle clamp 
 and keep the nerve intact. Pinch the end of the nerve and ob- 
 serve what happens 
 to the muscle. 
 
 (6) Touch the 
 nerve with filter 
 paper wet with the 
 acetic acid. What 
 happens ? 
 
 (c) Place the elec- 
 trodes of the induc- 
 torium on the nerve 
 and stimulate with a 
 "break" shock. (A 
 break shock is pro- 
 duced when the cir- 
 cuit is broken by 
 raising the key. ) 
 What happens when 
 the nerve is stimu- 
 lated? 
 
 Experiment 2. To study the effect of cold and heat on muscular 
 contraction. 
 
 Material. Hand dynamometer (this instrument may be 
 borrowed from the physical education teacher), ice, and a large 
 
 FIG. 104. The ergograph ; about one fifth 
 the actual size. 
 
 1 Apparatus for experiments in physiology may be obtained from the 
 Barvard Apparatus Co., Back Bay station, Boston, Mass. 
 
The Muscles in Action and the Hygiene of Exercise 143 
 
 This 
 three 
 
 Method and observation. 
 
 (a) Cool the hand and arm up to the elbow in ice water, 
 will cool the muscles which control the fingers. Make in 
 trials the maximal contraction on the dynamometer. 
 
 (6) Warm the hand and arm with heat and massage, and again 
 make three trials on the dynamometer. 
 
 (c) Compare the results in (a) and (6). What do these results 
 suggest for athletic activities and work in the gymnasium ? 
 Experiment 3. To study the effect 
 of exercise on size of muscle. 
 
 Material. A non-stretchable and 
 non-shrinkable tape. 
 
 Method and observation. Measure 
 the circumference (girth) of the biceps 
 and triceps in the largest part of the 
 upper arm. Write this measurement 
 in your book and record the date. 
 For a period of one month daily ex- 
 ercise the arm with dumbbells, chin- 
 ning, or some other exercise which 
 the physical education director will 
 show you and again measure the arm 
 in the largest part. How much has 
 it increased in size ? 
 
 Have the class tabulate on the 
 board the gain and indicate the type 
 of exercise chosen. 
 
 Experiment 4. To study the effect of 
 exercise on secretion of sweat. 
 
 (a) Swing Indian clubs for five 
 minutes and note whether perspira- 
 tion comes out on the face or body. 
 
 (6) After resting " run in place " 
 for the same length of time and 
 notice whether there is visible per- 
 spiration on the face or body, 
 difference ? 
 Experiment 5. To study muscular contraction and fatigue. 
 
 Material. Ergograph (Fig. 104). 
 
 Method and observation. Clamp the iron angle to a table 
 (Fig. 104) and fasten the second, third, and fourth fingers to the 
 wooden support. Upon the index finger, adjust the rod as shown 
 
 FIG. 105. The kymograph 
 and its aluminium drum ; about 
 one fifth the actual size. 
 
 Why should there be this 
 
144 Healthful Living 
 
 in the picture. Record the movement of the rod on a kymograph 
 (Fig. 105). A highly glazed paper, smoked by a flame, is pasted on 
 the drum to receive the tracing. 
 
 Does fatigue occur? To what is that due? Try the experiment 
 after the day's work in school and before beginning the day. Do 
 you notice any difference ? 
 
 GLOSSARY 
 
 ^Esthetic dancing. A form of dancing that attempts to produce 
 beautiful poses and movements. The movements are denned 
 and exact and are supposed to cultivate grace and harmony 
 in action. 
 
 Albumin. A transparent, nitrogen-containing substance found in 
 the blood and in many animal and vegetable juices and solids. 
 It is a chief constituent of muscle. It has the very complex 
 chemical formula (C 7 2Hii2Ni 8 SO22) . 
 
 Carbohydrate. One of a group of chemical compounds con- 
 taining carbon combined with oxygen and hydrogen in a 
 definite way. The carbohydrates include the group of sugars 
 represented by glucose (CeH^Oe), the double sugars, such as 
 cane (Ci 2 H 2 20n), and the starches, which are the simple sugars 
 combined in large chemical masses (CeHioOs),,. 
 
 CoSrdination. The act of harmonious motion so that parts are 
 related to produce movements or actions that are not an- 
 tagonistic. 
 
 Die Treppe. A German word meaning the staircase. Used to 
 describe the stairlike appearance of the graph made by a 
 muscle when its contractions are recorded. 
 
 Dynamometer. An instrument for measuring force or power 
 exerted by the muscles in doing work. 
 
 Fat. A greasy, easily melted, and soluble compound, forming 
 a part of animal tissue and also found in plants. Fats consist of 
 fatty acids such as palmitic, stearic, oleic, butyric, in combina- 
 tion with glycerin. The formula of butter, a common fat, is 
 
 Fatty degeneration. Cells of the body, especially muscle cells, 
 may undergo degeneration. In the process, the characteristic 
 structure of the cell is destroyed, and fat globules become 
 deposited in the cell. Such a change in muscle is serious, be- 
 cause fat cannot do the work of the contractile fibers formerly 
 present in the cell. 
 
The Muscles in Action and the Hygiene of Exercise 145 
 
 Folk dances. Dancing that has been derived from the peasants 
 of a nation, as a rule. The folk dance arose in a spontaneous 
 way in an effort of the people to express their thoughts, feel- 
 ings, and emotions. 
 
 Graphic representation. To represent by writing, or recording. 
 
 Lung capacity. The amount of air that can be breathed in by 
 the greatest possible inspiration after the greatest possible 
 expiration. It is measured by an instrument called the 
 spirometer. 
 
 Narcotic. A substance that produces depression of activity in 
 the body. In large doses it may produce stupor and even 
 death. 
 
 Protein. A highly complex chemical compound containing 
 carbon, hydrogen, oxygen, nitrogen, and often sulphur. It 
 contains nitrogen, and so differs from fat and carbohydrate. 
 
 Psycho-motor. A term that expresses the functioning of the 
 neuro-muscular mechanism. 
 
 Voltaic cell. A jar containing a liquid in which two metals are 
 immersed and capable of producing electricity through chem- 
 ical action. 
 
CHAPTER IX 
 FOOD AND ITS ELEMENTS 
 
 I. Nutritive and Non-nutritive Elements in Food. 
 Protein 
 
 Carbohydrates 
 Fats 
 Water 
 
 Mineral matter 
 Table of food elements 
 II. Composition of Foods. 
 
 III. Sources of Food Elements. 
 
 Protein 
 Fats and oils 
 Carbohydrates 
 
 IV. Uses of Food in the Body. 
 
 V. Proportion of Food Elements in a Normal Diet. 
 VI. Calculation of Food Values. 
 VII. The Diet of Different Peoples. 
 
 VIII. The Body's Method of Regulating the Food Supply. 
 IX. The Work of Enzymes in Digestion. 
 Examples of enzyme action 
 Classification of enzymes 
 
 Nutritive and non-nutritive elements in food. The food 
 material used by man may be grouped under two heads, 
 nutritive* and non-nutritive constituents. Nutritive ele- 
 ments are substances capable of combustion and the pro- 
 duction of energy. Now, there are certain salts whose 
 presence is necessary for life, but since they are not burned, 
 they will be classed as non-nutritive. The nutritive sub- 
 stances are: (1) protein, 1 (2) fat, and (3) carbohydrate; 
 
 1 The attempt a few years ago to secure the use of the German word 
 "Proteid" for the nitrogen-containing foods was not successful, due largely 
 
 146 
 
Food and its Elements 147 
 
 the non-nutritive are (1) water, (2) mineral matter, and 
 (3) waste, such as bones, stones of fruit, cellulose. 
 
 Protein. Protein is formed by living matter ; it always 
 contains nitrogen. There are definite proteins, such as 
 albumin, haemoglobin,* globulin,* etc. Protein is the great 
 tissue-building material and consequently is very important 
 in the diet during the period of growth. 
 
 Carbohydrates. (Sugars and starches.) Why are roast- 
 ing-ears sweet, although mature corn is not? It is because 
 the sugar in the former has been changed to starch in the 
 latter. On the other hand, ripe apples are sweet because 
 the starch present when the apple is green has been changed 
 to sugar. Starch and sugar are so nearly alike in composi- 
 tion and change so readily into each other, that as foods 
 they are classed together. 
 
 The carbohydrates include sugars, starches, and gums, 
 and form the principal element in vegetables. They are 
 found in vegetables, nuts, fruits, grains, milk, and, to a 
 slight extent, in meat and fish. 
 
 Fats. The fats come from both animal and vegetable 
 sources. Butter, cream, fat of meat, olive oil, and nuts 
 provide the main supply of fat. 
 
 Water. Water plays a very important part in the body 
 by affording a medium for solution of the food elements 
 after and during the digestive process. 
 
 Mineral matter. There are in some proteins mineral ele- 
 ments in chemical combination. This does not prevent 
 the classification of these as proteins, and in such cases the 
 salt present may play an important part in combustion. 
 
 to the work of Halliburton and Hopkins. These physiologic chemists 
 prepared a report on the use of the word "protein," and this report was 
 adopted by a joint committee of the American Physiology Society and the 
 American Society of Biological Chemists. 
 
 In this book, therefore, the word " protein" will be used to designate the 
 nitrogen-containing foods, which consist so far as is known at present of - 
 amino acids and their derivatives. 
 
148 Healthful Living 
 
 In general we may say the mineral matter of food is not 
 oxidized to produce heat. The minerals in combination with 
 protein are known as organic minerals. There are inorganic 
 minerals in the body, and they play, an important part in the 
 transfer of substances from the blood to the tissues and of 
 waste from the tissues to the blood. 
 Table of food elements. 
 
 Food stuffs 
 
 Nutritive 
 
 Non-nutritive 
 
 protein nitrogenous 
 
 fat 1 
 
 carbohydrate } ^on-nitrogenous 
 
 water 
 
 mineral matter 
 
 waste 
 
 The carbohydrates contain a greater amount of carbon 
 than the proteins; remember, however, that proteins have 
 some carbon. 
 
 Composition of foods. Very few of the articles of food 
 that we eat consist of only one of the classes of food ele- 
 ments mentioned ; most foods consist of several elements 
 combined. Oatmeal, for instance, contains starch, a small 
 proportion of fat, a large proportion of protein, some mineral 
 salts, and water. Let us see how the four classes are repre- 
 sented in milk. The part that makes it liquid is water, the 
 sweetness comes from the sugar, the fat rises as cream, and 
 the curd, from which cheese is made, contains casein,* a form 
 of protein. 
 
 Sources of food elements. All parts of plants may 
 furnish food; the seed, as the various grains, nuts, and 
 fruits ; leaves, as lettuce, cabbage, dandelion ; roots and 
 tubers, as potatoes, beets, turnips, tapioca (root of cassava) ; 
 stem, as sago (pith of sago palm) ; saps, as sugars (of cane, 
 beets, and maple tree). 
 
 Protein. Examples of proteins are : albumin, in white 
 of egg ; gluten,* the sticky or gluey part of grain ; casein, in 
 cheese and the curd of milk ; fibrin, in the blood of animals ; 
 
Food and its Elements 149 
 
 myosin,* the basis of lean meat ; gelatin, obtained from bones 
 and ligaments by boiling; vegetable protein, in beans and 
 peas ; and the protein of nuts. 
 
 Fats and oils. Fats and oils are found in : cream of milk, 
 yolk of egg, oil of nuts, olives, cottonseed, cocoanut, and 
 fat of meat. 
 
 Carbohydrates. Carbohydrates are found (a) as starch in 
 corn, wheat, rice, oats, and other grains, potatoes, cassava, 
 arrowroot, sago (in this country the last two are usually 
 potato starch sold under those names), beans, peas; (6) as 
 sugar in sugar cane, sorghum, dates, honey (almost pure 
 sugar), bananas (20 per cent), grapes, fruits, beets, maple 
 sap. 
 
 Uses of food in the body. Food has two uses in the 
 body ; first, to construct and repair tissues ; and second, to 
 produce energy for action. This action may be muscular 
 action, which can be seen, or it may be nerve impulses or 
 digestive process, the results of which only are seen. The 
 tissue builders are protein food such as lean meat, eggs, milk, 
 wheat, and vegetable proteins. This food may be used to 
 produce energy if the fats and carbohydrates are insufficient 
 in amount. The fats and carbohydrates furnish to a large 
 extent the energy required. To some extent the fat of food 
 may be stored in the body as fat, but only when taken in 
 amounts above that required for producing energy. Fat 
 in the body in large amounts is not desirable. There is no 
 advantage and there is a distinct disadvantage in storing 
 up a great excess of body fat. Such a condition is like putting 
 money in the bank without receiving any interest on it. The 
 mineral matter is absolutely essential in the formation of 
 bone and in the internal transfer of substances. The usual 
 mixed diet will provide .with the exception of sodium chloride 
 (common table salt) sufficient mineral matter for the body 
 needs. From experiments it has been shown that alcohol 
 is oxidized in the body, furnishing heat. On this basis it is 
 
Healthful Living 
 
 sometimes called a food. Under no conditions, however, 
 does it serve to repair old or build new tissue. On the other 
 hand, it is such a powerful drug, with such habit-forming 
 and undesirable properties, that it is not to be considered 
 as a desirable food. 
 
 Proportion of food elements in a normal diet. Ex- 
 perience has shown that the diet best suited for the body 
 should contain, besides water, protein one part, fat one to 
 two parts, and carbohydrates three to four parts. It is con- 
 ceded that people eat more protein than is necessary or de- 
 sirable. Authorities differ in their recommendation, but it is 
 quite generally held to-day that for the proper nourishment 
 of the body the problem is how much protein shall be used. 
 There is substantial agreement as regards the energy foods : 
 the fats, and the carbohydrates. The following dietaries* 
 are recommended by Atwater and Voit : 
 
 ATWATER'S STANDARDS 
 
 PROTEIN 
 GRAMS 
 
 FAT 
 GRAMS 
 
 CARBO- 
 HYDRATES 
 GRAMS 
 
 FUEL 
 VALUE 
 CALORIES 
 
 Man at very hard muscular work 
 Man at hard muscular work . . 
 Man at moderate muscular work 
 Man at light to moderate muscular 
 work 
 
 161 
 138 
 115 
 
 103 
 
 
 
 5500 
 4150 
 3400 
 
 3050 
 
 Man at sedentary or woman at 
 moderate work 
 
 92 
 
 
 
 2700 
 
 Woman at light muscular work . 
 
 83 
 
 
 
 2450 
 
 VOIT'S STANDARDS 
 
 PROTEIN 
 
 FAT 
 
 CARBO- 
 HYDRATES 
 
 FUEL 
 
 VALUE 
 
 GRAMS 
 
 GRAMS 
 
 GRAMS 
 
 CALORIES 
 
 Man 
 
 at hard work 
 
 
 133 
 
 95 
 
 437 
 
 3270 
 
 Man 
 
 at moderate work .... 
 
 109 
 
 53 
 
 485 
 
 2965 
 
 It will be noticed that in Atwater's table the amount of 
 energy foods is omitted. The amount of fat or carbohy- 
 
Food and its Elements 151 
 
 drate may vary as long as the total amount of both is suf- 
 ficient, together with the protein, to supply the required 
 energy. From the table of food values on page 153 select 
 sufficient amounts of fats and carbohydrates to yield, to- 
 gether with the protein, the calories * as given in the last 
 column in Atwater's Standards. 
 
 Other authorities recommend a lower protein intake. Dur- 
 ing the first year of the Great War, Thompson and Ballod 
 investigated the food consumption of Great Britain. Ac- 
 cording to Thompson, a British physiologist, the protein 
 intake per day was 2.70 ounces (1 ounce =31.1 grams) ; esti- 
 mate of Ballod, a German statistician, was 3.75 ounces. Both 
 estimates are considerably lower than the protein propor- 
 tion given by Voit or Atwater. Professor Chittenden of 
 Yale University has shown that health may be maintained, 
 for a long period, with a protein intake as low as 50 grams 
 per day. The experience of the German people has appar- 
 ently proved the validity of the lower figure for protein. It 
 may be stated, therefore, that the protein intake daily need 
 not exceed 100 grams. 
 
 Calculation of food values. Food is of use in the body 
 because on oxidizing it produces heat. The heat energy 
 of food is measured in terms of the great calorie, and a great 
 calorie 1 is defined as that amount of heat necessary to raise 
 one kilogram of water from to 1 C, or one pint about 
 4 F. By experiment it has been found that the following 
 is the caloric value of the three food elements : 
 
 1 gram of protein yields 4.1 calories 
 
 1 gram of fat yields 9.3 calories 
 
 1 gram of carbohydrate yields 4.1 calories 
 
 Now the number of calories required varies with the size 
 of the individual, the character and amount of work, and the 
 
 1 This is the Great Calorie. The small calorie is the amount of heat re- 
 quired to raise one gram of water one degree C. 
 
152 Healthful Living 
 
 condition of health. Langworthy follows Atwater's Stand- 
 ards and gives the following requirements : 
 
 Man doing no muscular work . . . 2450 calories a day 
 Man doing light muscular work . . 2700 calories a day 
 Man doing light to moderate muscular 
 
 work 3050 calories a day 
 
 Man doing moderate muscular work 3400 calories a day 
 Man doing very hard muscular work 5500 calories a day 
 
 Lumbermen working during the winter months in the 
 Maine woods consume food in a single day that yields 8000 
 calories. The average man should use about 3000 calories and 
 this will be obtained by taking in a day 100 grams of protein, 
 150 grams of fat, and 350 grams of carbohydrate. Brain 
 workers do not need so many calories as laborers in the field 
 or factory. There is no particular kind of food that will 
 serve as " brain food," although fish and certain prepared 
 foods are often claimed to have that virtue. 
 
 The caloric needs of an individual form the basis for de- 
 termining the food needs of a nation. It is with scientific 
 exactness, therefore, that the Belgian Relief Commission cal- 
 culated, " until after the harvest of 1919 it must feed ten 
 million people in Belgium and Northeastern France. They 
 will require, in twelve months, forty- two million bushels of 
 breadstuffs and over three hundred million pounds of meat ; 
 the children alone must have seventy-three million pounds of 
 condensed milk and cocoa and forty million pounds of sugar." 
 
 The study of the following table, 1 arranged from Locke, 
 will show the quantity and the caloric value of different foods. 
 Select from this table and write on the blackboard the articles 
 and quantity which will be necessary to provide, approxi- 
 mately, 100 grams of protein, 150 grams of fat, and 350 grams 
 of carbohydrate. Compute the caloric value. In some 
 cases it will be desirable to select two portions of the food. 
 
 1 Selected from Food Values by Edwin A. Locke 
 
 h. tbs. = heaping tablespoonful 
 h. ts. = heaping teaspoonful 
 
Food and its Elements 
 
 153 
 
 
 
 M 
 
 
 PROTEIN 
 
 FAT 
 
 CARBOHY- 
 
 
 g g 
 
 
 
 i 
 
 a 
 
 o 
 
 
 
 DRATE 
 
 
 
 3 1 
 
 
 QUAN- 
 
 l! 
 
 L 
 
 & -- 
 
 
 0) 
 
 "S 
 
 8 
 
 i 
 
 "8 
 
 H 
 
 S * 
 
 ll 
 
 FOOD 
 
 TITY OF 
 
 fe W 
 
 5 
 
 o c 
 
 1 '" 
 
 
 
 O < 
 
 2 ^ 
 
 00 03 
 
 S * 
 
 
 FOOD 
 
 oO 
 
 H > 
 
 o 
 
 1 
 
 >f 
 
 c 
 
 > S t 
 
 < 2 
 
 >% 
 
 
 I-J z 
 
 
 
 WEIGH 
 i] 
 
 i~ 
 
 
 K 
 
 
 
 O 
 
 r 
 
 j 
 
 C 
 
 'E ,0 
 
 S 
 o 
 
 I 
 
 Roast beef . . 
 
 1 slice 
 
 100 
 
 48.20 
 
 22.30 
 
 91.4 
 
 28.6 
 
 266 
 
 
 
 357 
 
 357 
 
 
 
 Roast lamb 
 
 1 slice 
 
 175 
 
 50.33 
 
 14.78 
 
 60.6 
 
 9.53 
 
 88.6 
 
 
 
 
 
 200 
 
 150 
 
 Mutton chop . 
 
 1 chop 
 
 100 
 
 71.80 
 
 22.60 
 
 92.7 
 
 4.5 
 
 41.9 
 
 
 
 
 
 135 
 
 135 
 
 Fried ham . . 
 
 1 slice 
 
 35 
 
 12.81 
 
 7.77 
 
 31.9 
 
 11.62 
 
 108.1 
 
 
 
 
 
 400 
 
 140 
 
 Butter . . . 
 
 1 ball 
 
 15 
 
 1.65 
 
 0.15 
 
 0.6 
 
 12.75 
 
 118.6 
 
 
 
 
 
 795 
 
 119 
 
 Cheese (Amer.) 
 
 1 cu. in. 
 
 20 
 
 6.32 
 
 5.70 
 
 23.6 
 
 7.18 
 
 66.7 
 
 0.6 
 
 .2 
 
 453 
 
 91 
 
 Milk (whole) . 
 
 1 glass 
 
 220 
 
 191.40 
 
 7.26 
 
 29.8 
 
 8.80 
 
 21.8 
 
 11 
 
 45.1 
 
 72 
 
 157 
 
 Egg (boiled) . 
 
 1 egg 
 
 50 
 
 36.60 
 
 6.60 
 
 27.1 
 
 6 
 
 55.8 
 
 
 
 
 
 169 
 
 83 
 
 Baked beans . 
 
 3 h. tbs. 
 
 150 
 
 91.17 
 
 10.83 
 
 44.4 
 
 12.76 
 
 118.7 
 
 32.84 
 
 134.6 
 
 199 
 
 298 
 
 Carrots . . . 
 
 3 h. tbs. 
 
 100 
 
 93.40 
 
 .53 
 
 2.2 
 
 .17 
 
 1.6 
 
 3.39 
 
 13.9 
 
 18 
 
 18 
 
 Corn (green) . 
 
 1 ear 
 
 100 
 
 72.6 
 
 3.07 
 
 12.6 
 
 1.10 
 
 10.2 
 
 18.78 
 
 77 
 
 100 
 
 100 
 
 Peas (green) . 
 
 3 h. tbs, 
 
 92 
 
 67.90 
 
 6.16 
 
 25.3 
 
 3.13 
 
 29.11 
 
 3.43 
 
 55.1 
 
 119 
 
 110 
 
 Potato (baked) 
 
 1 med. 
 
 130 
 
 90.87 
 
 3.77 
 
 15.5 
 
 .20 
 
 1.9 
 
 32.07 
 
 131.5 
 
 114 
 
 149 
 
 Apple . . . 
 
 av. size 
 
 150 
 
 94.90 
 
 .45 
 
 1.8 
 
 .45 
 
 4.2 
 
 16.2 
 
 66.4 
 
 49 
 
 72 
 
 Orange . . . 
 
 av. size 
 
 250 
 
 158.5 
 
 1.5 
 
 6.2 
 
 .25 
 
 2.3 
 
 21.25 
 
 87.1 
 
 37 
 
 96 
 
 Marmalade 
 
 1 h. tbs. 
 
 30 
 
 4.35 
 
 .18 
 
 .7 
 
 .03 
 
 .3 
 
 25.35 
 
 103.9 
 
 349 
 
 105 
 
 Bread (white) 
 
 1 slice 
 
 30 
 
 10.59 
 
 2.76 
 
 11.3 
 
 .39 
 
 3.6 
 
 15.93 
 
 65.3 
 
 268 
 
 80 
 
 Bread (whole 
 
 
 
 
 
 
 
 
 
 
 
 
 wheat) . . 
 
 1 slice 
 
 42 
 
 16.13 
 
 4.07 
 
 16.7 
 
 .38 
 
 3.5 
 
 20.87 
 
 85.6 
 
 251 
 
 106 
 
 Crackers 
 
 
 
 
 
 
 
 
 
 
 
 
 (graham) 
 
 1 cracker 
 
 8 
 
 .43 
 
 .80 
 
 3.3 
 
 .75 
 
 7.0 
 
 5.90 
 
 24.2 
 
 429 
 
 34 
 
 Ham sandwich 
 
 1 sand. 
 
 70 
 
 24.15 
 
 7.28 
 
 29.8 
 
 10.07 
 
 93.7 
 
 26.65 
 
 109.3 
 
 332 
 
 233 
 
 Oatmeal . . 
 
 2 h. tbs. 
 
 100 
 
 84.50 
 
 2.80 
 
 11.5 
 
 .50 
 
 4.7 
 
 11.50 
 
 47.2 
 
 63 
 
 63 
 
 Rice (boiled) . 
 
 1 h. tbs. 
 
 100 
 
 72.50 
 
 2.80 
 
 11.5 
 
 .10 
 
 .9 
 
 24.40 
 
 100 
 
 112 
 
 112 
 
 Shredded 
 
 
 
 
 
 
 
 
 
 
 
 
 wheat bis. . 
 
 1 biscuit 
 
 29 
 
 2.35 
 
 3.05 
 
 12.5 
 
 .41 
 
 3.8 
 
 22.59 
 
 92.6 
 
 375 
 
 109 
 
 Spaghetti . . 
 
 3 h. tbs. 
 
 145 
 
 111.21 
 
 4.52 
 
 18.5 
 
 2.81 
 
 26.1 
 
 25.76 
 
 105.6 
 
 103 
 
 150 
 
 Cake choc. . . 
 
 av. slice 
 
 70 
 
 14.30 
 
 4.34 
 
 17.8 
 
 5.67 
 
 52.7 
 
 44.87 
 
 184 
 
 364 
 
 255 
 
 Sugar cookies . 
 
 1 cooky 
 
 11 
 
 .91 
 
 .77 
 
 3.2 
 
 1.12 
 
 10.4 
 
 8.05 
 
 33 
 
 423 
 
 47 
 
 Granulated 
 
 
 
 
 
 
 
 
 
 
 
 
 sugar . . . 
 
 1 h. ts. 
 
 10 
 
 
 
 
 
 ~ 
 
 10 
 
 41 
 
 410 
 
 41 
 
 
 
 
 
 The diet of different peoples. Milk has an excess of 
 nitrogen, and oatmeal an excess of carbon ; oatmeal and 
 milk form a perfect food, and it is not surprising that the 
 Scotch people, with whom it has been a chief food, are a 
 sturdy race. Potatoes are mostly starch and water; the 
 starch in them is nearly nine times as much as the protein, 
 and an Irishman who tried to live on potatoes alone would 
 have to eat seven pounds a day to get enough protein. By 
 
154 Healthful Living 
 
 eating milk and eggs also, he can get along on half the 
 amount of potatoes named above. Every Irish peasant is 
 said to keep a cow and chickens. The Mexicans eat bread 
 made of corn meal, and supply the protein by using beans 
 as a constant article of diet. The Zulus live on cracked 
 corn by adding milk to it. The Arabs live on barley and 
 camels' milk, rarely eating the camels' flesh. Hundreds of 
 millions of people in Asia (the Hindoos, Chinese, and others) 
 subsist mainly on rice, which is more nearly pure starch 
 than any of the grains, containing only 6 per cent of protein, 
 about half as much as wheat and corn; the chief addition 
 they make is butter or other fat, and beans, which contain 
 vegetable protein. Their meager diet may partly account 
 for their lack of energy and bravery, and the ease with which 
 they are conquered and controlled by European nations. 
 The greatness of a people is greatly influenced by their diet. 
 
 The body's method of regulating the food supply. We 
 should not think that the food eaten must be regulated with 
 the greatest precision. Any reasonable excess will pass 
 through the canal unabsorbed, without great injury to the 
 body. The lack of any of the necessary elements will be 
 well tolerated for a time until a craving for a certain kind 
 of food will lead later to the supply of the elements needed. 
 If a person feels bad, or the digestion seems weak, some will 
 advise dieting. There is a tendency among certain writers 
 on hygiene to overrate the importance of this subject. If 
 the laws of health in regard to fresh air, muscular exercise, 
 sleep, cleanliness, temperature, and abstinence from the use 
 of stimulants be observed, our appetites usually will be a 
 sufficient guide in the matter of diet. These matters should 
 first be looked to, and dieting then will probably become 
 unnecessary. 
 
 It is an instructive and important fact, that too much 
 consciousness of what is eaten and too much dwelling on 
 what might be the consequence of eating this food or that 
 
Food and its Elements 155 
 
 food, may interfere seriously with good digestion. If the 
 sense of taste is not abused, but its promptings treated with 
 great respect, we shall preserve a useful guide which will 
 tell us more perfectly what is needed than any scientific 
 table can do. Food that brings discomfort after eating, 
 however, should not be eaten. 
 
 The work of enzymes * in digestion. The preparation of 
 food in the body so that it can be assimilated (taken up by 
 the cells) is a process in which certain digestive juices act 
 upon the food mass. The action of these juices is effective 
 because they contain substances which break up the food 
 masses into smaller units. This breaking up is accomplished 
 by bodies known as enzymes. It is important to under- 
 stand what their nature is. 
 
 Example of enzyme action. The souring of milk, the 
 putrefaction* of animal substances, and the fermentation of 
 food materials have been explained in various ways in past 
 years. These phenomena led to investigations, and it was 
 learned that the chemical action going on differed from other 
 chemical action in that the substance producing the change 
 was not destroyed or used up in the reaction. Pasteur 
 showed that fermentations were due to bacterial action. It 
 was later learned that there were other substances produced 
 by living cells which would cause changes in food. These 
 substances are known as enzymes. They have special 
 names, for example, the enzyme of the saliva is ptyalin, of 
 the gastric juice, pepsin and rennin, of the pancreatic juice, 
 trypsinogen, lipase, etc. Enzymes act to produce a chemical 
 change, but they themselves do not enter into the reaction. 
 What is catalysis* in chemistry? Are enzymes similar to 
 catalyzers ? 
 
 The action of the enzyme is always specific. The ptyalin 
 of the saliva changes starch to sugar, but it has no effect on 
 protein. Each enzyme acts on a particular kind of food 
 material ; it is fitted to it " as a key to its lock." 
 
156 Healthful Living 
 
 Classification of enzymes. If digestion is thought of as a 
 process similar to the work of a stone cutter, who takes a 
 rough mass of stone and cuts it up into blocks of a certain 
 size to fit into a particular place in the building, then the 
 action of enzymes may be likened to the chisels which break 
 the stone. This breaking down of food compounds into 
 smaller units is called " splitting," and so we speak of protein- 
 splitting enzymes, fat-splitting enzymes, etc. 
 
 1. Protein-splitting enzymes. Pepsin (gastric juice) and 
 trypsinogen (pancreatic juice). They cause in a reaction 
 with water a splitting of the protein into smaller units 
 capable of absorption by the body cells. This action with 
 water is called hydrolysis.* 
 
 2. Starch-splitting enzymes. Ptyalin (saliva) and amylase 
 (pancreatic juice) . The action in this case is one of hydrolysis. 
 The starch molecule is converted into a less complex one, a 
 sugar, in the form of two molecules of sugar (disacchride) . 
 
 3. Sugar-splitting enzymes. These split the disac- 
 chrides into monosacchrides. Examples, maltase, which 
 con verts, maltose into two molecules of dextrose; invertase, 
 which splits, cane sugar into dextrose and levulose ; and 
 lactase, which splits milk sugar into dextrose and galactose. 
 The following f ornlula * indicates what this change is : 
 
 Ci 2 H 22 Oii+H 2 0+maltase = C 6 Hi 2 6 +C 6 H l2 O 6 + maltase 
 
 III III 
 
 maltose water enzyme dextrose dextrose enzyme 
 
 The enzyme maltase causes the change; it is not de- 
 stroyed or used up in the process. 
 
 4. Fat-splitting enzymes. Lipase (pancreatic juice and 
 bile). This acts by hydrolysis; as, 
 
 C3H 5 (Ci8H 3 50 2 ) 3 +3H 2 0+lipase = C 3 H 5 (OH) 3 +3(C 18 H 36 02) 4-lipase 
 
 I I I I I 
 
 Tristearin water enzyme glycerin stearic acid enzyme 
 
 The fat mass tristearin found in beef fat is broken down 
 into glycerin and stearic acid. 
 
Food and Us Elements 157 
 
 GLOSSARY 
 
 Albuminoid. Substance similar in composition to albumin. 
 
 Calorie. Food when it undergoes combustion produces heat. 
 This heat is measured by standards and th'e unit of heat used 
 as the standard is the calorie. - The greater calorie is the 
 amount of heat required to raise one kilogram of water one 
 degree C. When speaking of the caloric value of food, it is 
 the greater calorie that is meant. 
 
 Casein. The name of the protein of milk after it has been coagu- 
 lated by the enzyme rennin. Before coagulation, the protein 
 is called caseinogen. 
 
 Catalysis. A chemical change brought about in a chemical com- 
 pound by an agent that does not enter into the action of the 
 change in a chemical way. 
 
 Dietary. A systematic arrangement of the diet. 
 
 Enzyme. A substance that induces digestive chemical action 
 in the food elements but does not enter itself into the chemical 
 change. The ptyalin of the saliva is an enzyme. 
 
 Formula. A group of symbols showing the composition or 
 structure of a chemical compound. 
 
 Gelatinoid. A substance similar in composition to gelatin. 
 
 Globulin. One of the proteins. The chief globulins in the 
 body are serum globulin and fibrinogen of the blood, myo- 
 sinogen of muscle, and globin in combination with hematin 
 in the red corpuscle. 
 
 Gluten. An essential element in the cereal wheat. It gives to 
 the flour important nourishing characteristics. It is a pro- 
 tein. 
 
 Haemoglobin. The iron-containing substance in the red corpuscle. 
 Chiefly noted for its ability to carry oxygen in chemical com- 
 bination. It is formed from a globulin, globin, and an iron 
 radical called hematin. 
 
 Hydrolysis. The chemical decomposition of a compound that 
 ensues when water (H 2 O) is absorbed by it. 
 
 Myosin. Formed from myosinogen. It comprises 75 per cent 
 of the protoplasm of muscle tissue. It is a protein. At 
 death it coagulates, and causes rigor mortis. 
 
 Nutritive. Having properties which promote nutrition. 
 
 Putrefaction. The act of breaking down of an organic compound 
 It represents decay and decomposition. 
 
CHAPTER X 
 THE DIGESTION OF FOOD 
 
 I. The Structure and Functions of the Alimentary Canal. 
 The mouth 
 The pharynx 
 The esophagus 
 The stomach 
 The small intestine 
 The large intestine 
 II. The Liver. 
 
 Anatomy 
 Functions 
 
 III. Diagram of Digestive Mechanism. 
 
 IV. The Waste Products from Food Elements. 
 
 The structure and functions of the alimentary canal. 
 Food, in order to be of service to the body, must undergo 
 several changes. Its nutritive portion must be separated 
 from the non-nutritive; and the former must be made 
 soluble, or in fit condition to be taken up by the blood and 
 carried to the tissues. This process is called digestion, and 
 the assemblage of organs by which it is carried on is called 
 the digestive system. The tube which forms the receptacle 
 for the food during digestion is called the alimentary * canal. 
 In the carnivora, or flesh-eating animals, whose food con- 
 tains but a small amount of indigestible matter, the ali- 
 mentary canal is comparatively short, being, when stretched 
 out, only three or four times the length of the body. In the 
 herbivora, or grass-eating animals, the canal is thirty times 
 the length of the body. In the hog, which is omnivorous 
 
 158 
 
The Digestion of Food 159 
 
 (" all-eating "), it is ten times the length of the body. If 
 man's trunk only is counted, the canal is twelve times as 
 long ; if his height is counted, the canal is six times as long. 
 
 The'alimentary canal has three coats in its walls throughout 
 its whole length. What is each for? The inner coat, or 
 lining, is a delicate epithelial tissue called the mucous mem- 
 brane. It forms a smooth lining to prevent friction, and 
 secretes a mucus which serves the same purpose. The next 
 coat is the submucous coat ; it is of elastic connective tissue, 
 and serves to toughen and strengthen the wall, and to bind 
 the mucous coat to the muscular coat. Outside of this is 
 the third coat. It is composed of several layers of invol- 
 untary muscular tissue, which, by its contraction, causes the 
 food to move along the canal (Fig. 114). 
 
 In the walls of the alimentary canal are numerous blood 
 vessels and lymphatics. Opening on its inner surface are 
 mouths of ducts from the various glands of the digestive 
 system. Some of the glands are of considerable size and lie 
 outside of the canal ; others are very minute and are em- 
 bedded in the walls of the canal ; their secretions render the 
 food soluble. 
 
 When we swallow food or drink, we are accustomed to say 
 that it is in the body, but anatomically and physiologically 
 this is not correct. It is on the outside anatomically, be- 
 cause the mucous membrane is continuous with the skin, 
 which is the external covering (Fig. 106). It is on the out- 
 side physiologically, because the food must pass through the 
 mucous membrane before it can be assimilated by the tissues 
 and become of use to the body. 
 
 A lean person often eats a great deal, expecting to get fat, 
 and finds that, although he has swallowed the food, the 
 nourishment has never really entered his body. 
 
 The mouth. The food is held in the mouth for a short 
 time while it is mixed with the watery alkaline fluid called 
 the saliva, and is ground up fine by the teeth. The partition 
 
i6o 
 
 Healthful Living 
 
 between the nose and the mouth is formed by the palate 
 bones, covered with mucous membrane. The larger part 
 of the roof of the mouth is formed by these bones and is 
 called the hard palate. The roof is completed in the rear 
 by the fleshy soft palate. The floor of the mouth is occupied 
 
 FIG. 106. The food materials must pass the mucous membrane lining 
 of the alimentary tract before they are within the body. The liver is dis- 
 placed upward to show the parts under it. 
 
 mostly by the tongue ; the lips form the front wall, and the 
 cheeks the side walls. The cheek is composed partly of a 
 large flat muscle called the buccinator (trumpeter, because 
 used in blowing a trumpet) . The contraction of the trump- 
 eter muscles, together with the movements of that flat 
 muscle called the tongue, keeps the food between the teeth 
 in the act of chewing, or mastication. 
 
 Salivary Glands. There are three pairs of glands that 
 
The Digestion of Food 161 
 
 secrete saliva. In structure one of these glands with its 
 duct resembles a minute bunch of grapes with a hollow stem. 
 The largest, called the parotid, is just beneath the skin in 
 front of the ear. Its duct opens into the mouth in the upper 
 jaw opposite the second molar tooth. This gland swells in 
 a disease called the mumps. The next largest gland is the 
 submaxillary, lying within the angle of the lower jaw. Its 
 duct opens into the floor of the mouth. The smallest, the 
 sublingual, lies farther to the front ; both glands of the pair 
 lie beneath the tongue, and open by a number of ducts. The 
 fluid produced by these glands becomes mixed with the mucus 
 from the mucous membrane of the mouth and is called the 
 saliva. 
 
 Saliva. Saliva is a thin, colorless, alkaline liquid, slightly 
 sticky, and often containing air bubbles. The digestive en- 
 zyme of the saliva -is ptyalin, which has the power to 
 
 FIG. 107. Cells of the salivary gland. A, after rest; B, after a short 
 period of activity ; C, after a prolonged period of activity. Shriveling and 
 loss of granules occur. 
 
 change starch to malt sugar. Maltase is also present 
 which changes the malt sugar to dextrose. From one to 
 three pints of saliva are produced daily (Fig. 107). Its flow is 
 excited by the act of chewing and by anything held in the 
 mouth, especially if it be of an agreeable taste or odor. 
 Hunger, or the sight or thought of agreeable food, makes 
 the " mouth water " by stimulating the cells in the glands 
 to activity by means of the nerves. But by far the most 
 powerful of all the excitants to the salivary flow is dryness 
 
162 
 
 Healthful Living 
 
 Right Tons/7 
 Poster/or 
 of Pharynx 
 
 Soft Palate 
 
 Uvula 
 
 Left Tons/7 
 
 of the food. Only one fourth as much saliva is deposited 
 in the same length of time when eating oatmeal and milk 
 as when eating crackers or dry toast. 
 
 The Tonsils. The tonsils * (Fig. 108) are large lymph 
 glands. They are oval in shape but vary greatly in size in 
 
 different people. 
 They become in- 
 fected frequently 
 and cause in this 
 way many cases of 
 heart disease and 
 rheumatism. * 
 Many people who 
 suffer from rheu- 
 matism could be 
 cured by proper 
 treatment of in- 
 fection existing 
 in the tonsils or 
 teeth. The ton- 
 sils can be re- 
 moved entirely 
 without injury to 
 the health, and if 
 they are diseased, removal of them will improve the health. 
 The use of tobacco is a common cause of diseases of the 
 throat. It causes a dry ness and thirst, and frequently leads 
 those who use it to take alcoholic drinks. Often the habit 
 of smoking produces a troublesome disease called smokers' 
 sore throat, which can be cured only after smoking has been 
 discontinued. The heat of smoking is very trying to the 
 organs, although not so injurious to them as the poison of 
 the tobacco. 
 
 Absorption * from the Mouth. The passage of digested 
 food into the blood vessels is an important sequel of the 
 
 FIG. 108. Structures within the mouth as seen 
 when it is open and tongue depressed. (Modified 
 after Coakley.) 
 
The Digestion of Food 
 
 163 
 
 digestive process. A little of the water containing sugar 
 
 and salts is absorbed from the mouth directly into the blood 
 
 vessels. Poisonous substances may sometimes be absorbed 
 
 from the mouth in sufficient quantities to produce death. 
 
 If a drop or two of prussic 
 
 acid should be placed on 
 
 the tongue or on the 
 
 mucous membrane of the 
 
 mouth, death would occur 
 
 in a few minutes, although 
 
 not a particle of it had 
 
 reached the stomach. 
 
 Boys who take their first 
 
 chew of tobacco learn in a 
 
 disagreeable way that the 
 
 entire body may be af- 
 
 fected by absorption from 
 
 the mouth. The absorp- 
 
 tion of food in the mouth 
 
 is insignificant in amount 
 
 compared to the absorp- 
 
 tion that takes place in 
 
 the small intestine. 
 
 The pharynx * (f ar'inks) . 
 
 -A muscular bag open- 
 
 ing from the nose and 
 
 month frmr anrl a half 
 niOUtn, lOUr and a halt 
 
 inches in length, lies 
 
 atraiW thp sninnl polumn 
 nurnn. 
 
 It is commonly called the 
 throat. There is an air passage from nose to lungs and a food 
 passage from mouth to stomach. They cross each other, and 
 the intersection is called the pharynx. There are seven 
 openings from the pharynx : one to the mouth, one below 
 the mouth into the trachea, one behind the trachea into the 
 
 FIG. 109. Mouth and upper part of 
 
 d, larynx; e, epiglottis; /, soft palate 
 and uvula ; 0, opening of left Eustachian 
 tube ; ^ opening of left lachrymal duct ; 
 i, hyoid bone ; k, tongue ; I, hard palate ; 
 
 m ' w ' base of skull; p ' 9 ' the scroll ~ 
 like or turbinated bones . Tt tonsiL 
 
164 
 
 Healthful Living 
 
 (Esophagus, 
 
 esophagus, and two pairs of openings in the upper pharynx ; 
 one of these pairs is to the nasal passages, and the other 
 pair is into the Eustachian tubes, which lead to the ears. 
 When swallowing, all of the openings close but the one to 
 the mouth and the one to the esophagus. (See Plate VII.) 
 
 The upper part of the pharynx, and thus the openings to 
 the nose and ears, can be closed by raising the tip of the soft 
 palate, or uvula,* against the back wall of the pharynx 
 
 (Fig. 109). Sudden 
 laughter or coughing 
 while swallowing may 
 cause the soft palate 
 to relax, and then a 
 portion of the food 
 or drink is sometimes 
 forced into the nose. 
 The opening to the 
 trachea can be closed 
 in two ways : by the 
 vocal cords contract- 
 ing and approaching 
 one another; or by 
 
 FIG. 110. The stomach, duodenum, and the drawing Upward 
 
 Stomach 
 'Pancreatic Duct 
 
 gall bladder laid open. 
 
 pleted the bile from the liver backs up into the 
 
 gallbladder. 
 
 When digestion is com- f ,, l arV nY tn 
 ( tne iar y nx * 
 
 epiglottis.* The 
 opening from the 
 
 mouth, called the fauces, can be closed by the contraction 
 of upright muscles, called the pillars of the fauces, which 
 connect the posterior part of the soft palate and the base 
 of the tongue. These muscles come together in the middle 
 like sliding doors. There are two of them on each side, 
 and the tonsils lie between them (Fig. 108). The tip of 
 the soft palate hangs down between the pillars, and is 
 called the uvula. By looking into a mirror with the 
 mouth very wide open and the tongue flattened, you can 
 
The Digestion of Food 165 
 
 see the palates, the pillars, the uvula, and perhaps the 
 tonsils. 
 
 The esophagus. The esophagus, which conducts the 
 food to the stomach (Figs. 109, 110), opens from the lower 
 part of the pharynx. It is about nine inches long, and lies 
 in front of the spinal column and behind the trachea. It 
 has the three layers found elsewhere in the alimentary canal, 
 and its walls are soft and he collapsed when no food or drink 
 is passing. The food is under reflex control after passing 
 the fauces. The contraction of the pharynx presses the food 
 down into the esophagus. A ring of the muscular tube con- 
 tracts just above the morsel. This contraction runs down 
 to the stomach, forcing the food before it as if a tight ring 
 were slipped down over the esophagus. A contraction of 
 any part of the alimentary canal in this manner, as if a wave 
 were traveling along, is called a peristalsis.* While a horse 
 is drinking, the peristaltic waves of the esophagus may be 
 plainly seen along the neck (Plate V) . 
 
 The stomach. The esophagus pierces the diaphragm to 
 the left of the center and enlarges into a pouch called the 
 stomach. This organ lies just under the diaphragm, mostly 
 on the left side of the abdomen and half covered by the lower 
 ribs. It is capable of holding about two quarts. When 
 full, it is about a foot long and five inches broad. Its shape 
 is not easily described (Fig. 110). It is placed across the 
 abdomen, and its left end is the larger. Its outline is 
 curved inward above and outward below. When empty, 
 it flattens and its walls touch, and the mucous lining 
 then lies in deep wrinkles or folds. The opening where 
 the esophagus ends, and through which the food enters, 
 is called the cardia, because it is near the heart. The 
 opening where the intestines begin, and through which 
 the food leaves, is called the pylorus* (gate keeper); both 
 openings can be closed by circular muscles in their 
 walls. 
 
i66 
 
 Healthful Living 
 
 Movements. Anything taken into the stomach causes 
 peristalsis. The food is caused to go from the esophagus 
 to the left of the cardiac orifice, then down to the right and 
 back again, the circuit from left to right, then from right 
 to left, taking from one to three minutes according to the ac- 
 tivity of the peristalsis. The muscular fibers in the walls 
 
 , of the stomach are in 
 
 three layers (Fig. Ill) ; 
 one layer runs length- 
 wise, another around, 
 b and the third obliquely, 
 so that the varied con- 
 tractions cause the food 
 to become thoroughly 
 mixed with the digestive 
 juice. 
 
 Secretion. The secre- 
 tion of the stomach is 
 called gastric juice. This 
 
 FIG. 111. A section through the wall i s a yellowish fluid and 
 of the stomach. (Magnified 15 diameters.) . , 
 
 a, surface of the mucous membrane, show- Consists Ot Water having 
 
 ing the openings of the gastric glands; in solution hydrochloric* 
 6, mucous membrane, composed almost . , , , 
 
 entirely of glands ; c, submucous, or areolar acid and *WO enzymes, 
 
 tissue; d, transverse muscular fibers; These remarkable Sub- 
 e, longitudinal muscular fibers ; /, peri- , . , 
 
 tonealcoat. stances, although exist- 
 
 ing in very small quanti- 
 ties, are able to change the composition of large quantities 
 of food. In times of rest, when there is no food present, the 
 mucous membrane of the stomach is of a pale red color. But 
 when food is introduced, a change at once takes place. The 
 membrane becomes charged with blood and consequently 
 turns to a deep red color. The gastric juice, secreted by 
 many small glands (Fig. 112), appears on the walls of the 
 stomach, and peristaltic action begins. 
 
 One enzyme of the gastric juice, called rennin, acts by 
 
The Digestion of Food 
 
 coagulating milk, a change somewhat like the coagulation 
 of the blood. It causes coagulation by acting upon the 
 protein part of the milk. It is especially abundant in child- 
 hood. The other enzyme, called pepsin, softens the protein 
 part of food and reduces it to .peptone, in which form it is 
 soluble in water. Pepsin, however, can act only when the 
 hydrochloric acid has ac- 
 cumulated to an amount 
 sufficient to neutralize* the 
 alkaline condition caused by 
 the saliva. This usually re- 
 quires about thirty or forty 
 minutes. The hydrochloric 
 acid, by its presence in 
 sufficient quantity, not only 
 enables the pepsin to act, 
 but also prevents fermenta- 
 tion of the food and kills all 
 germs that may enter the 
 stomach. 
 
 The saliva continues its 
 work even in the stomach 
 until neutralized by the acid. 
 The pepsin then begins to 
 act. The outside of the food 
 particles is acted upon first, 
 and this digested part is then 
 rubbed off by the peristaltic 
 movements, and the next layer is acted upon. Its action is 
 confined to the protein. In fat meat the albuminous walls 
 of the cells are eaten away and the fat is set free but not 
 digested. Starch may also be set free from albuminous 
 envelopes. The food is thus reduced to a semifluid condi- 
 tion and is called chyme.* 
 
 After the food has been reduced to chyme, the pylorus 
 
 FIG. 112. Three glands of the 
 stomach, e, epithelium at inner sur- 
 face of stomach ; m, mouth of gland ; 
 p, principal cells of gland ; ov, ovoid 
 cells ; c, connective tissue below and 
 between the glands. 
 
1 68 Healthful Living 
 
 opens every minute or two, permitting a little of the chyme 
 to escape into the intestine. But if some hard object, as a 
 button, or a lump of raw starch from an unripe apple in- 
 sufficiently masticated, enters the stomach, the pylorus, 
 after a while, will become fatigued and will relax and allow 
 it to pass without becoming semifluid. 
 
 Action of the Acid Chyme. As the acid chyme passes 
 into the duodenum it causes an important chemical action. 
 When the acid chyme comes in contact with the mucous 
 membrane of the intestinal wall some of it is absorbed, and 
 this, acting on an enzyme (prosecretin) in the intestinal cells, 
 causes the formation of another enzyme, secretin. The 
 secretin passes into the blood and, coming to the liver, 
 pancreas, and cells of the intestinal walls, causes these organs 
 to pour out their digestive juices. For many years it was not 
 understood how the pancreas or liver could know when to 
 free their digestive juices, because the food did not come in 
 direct contact with their cells. It is the secretin, therefore, 
 which tells these organs when they must give up their juices 
 for digestive purposes. The secretin causes the flow of the 
 pancreatic juice, the bile, and the intestinal juice (page 184). 
 
 Absorption from the Stomach. A slight absorption may 
 take place in the stomach of a portion of the protein digested 
 there. Some of the sugar resulting from the salivary diges- 
 tion of starch by the saliva may also be absorbed. Nearly 
 all the absorption of the food takes place in the small in- 
 testine, and it is there likewise that most of the digestion 
 occurs ; for, upon leaving the stomach, the greater part of 
 the protein, carbohydrates, and all the fats and oils, remain 
 to be acted upon. 
 
 The Stomach as a Storehouse. It is a common notion 
 that digestion is carried on chiefly in the stomach. Some 
 physiologists give tables stating that pork requires five hours 
 for digestion, fried beef four hours, roasted beef three hours, 
 apples one hour, etc. ; what is meant is that it requires that 
 
The Digestion of Food 
 
 169 
 
 length of time for these foods to leave the stomach, the di- 
 gestion being far from complete. Investigation in the last 
 few years shows that the stomach is a kind of storeroom or 
 antechamber in which food is stored, being softened and 
 kept free from germs and gradually delivered to the intestine. 
 
 Of the thirty or more feet of the alimentary canal, the 
 food, upon leaving the stomach, has traversed about two feet. 
 Of the fourteen hours required for digestion, about three or 
 four hours have passed. A portion of the starch and protein 
 has been digested and a small amount of each absorbed by 
 the blood vessels/ The fats have not yet been acted upon. 
 
 It is essential that the part performed by each prior organ 
 should be well performed, for this determines whether the 
 changes in the food in the next organ shall be easily and com- 
 pletely accomplished. If the food is thoroughly masticated 
 in the mouth and the saliva well mixed with it, this alkaline 
 condition excites the flow of the acid 
 gastric juice, which otherwise would be 
 scanty. If the gastric juice is strong 
 and acts freely upon the food, the 
 acidity of the food as it leaves the 
 stomach and enters the small intestine 
 excites the flow of the alkaline intes- 
 tinal juices. 
 
 The small intestine. When the 
 chyme passes the pylorus, it enters the 
 small intestine, which is a tube about 
 as large around as the thumb, and 
 about twenty feet long, lying coiled in 
 the central part of the abdominal 
 
 FIG. 113. A portion 
 
 cavity. The first part of it, about ten O f small intestine 'cut 
 inches in length, is called the duodenum * folds 
 
 (from a word meaning twelve, because 
 
 its length is twelve fingers' breadth). The mucous and 
 
 submucous coats of the small intestine are wrinkled by 
 
1 70 
 
 Healthful Living 
 
 numerous folds which are crescent-shaped, since no single 
 fold goes entirely around the tube (Fig. 113). The folds 
 
 are so numerous that 
 they occupy almost 
 the entire inner sur- 
 face. The small in- 
 testine is the chief 
 organ of absorption 
 as well as of diges- 
 tion, and the absorb- 
 ing surface is greatly 
 increased by the 
 folds. On and be- 
 tween the wrinkles 
 are innumerable tiny 
 projections called 
 villi * (Fig. 114). 
 Each villus contains 
 a loop of blood vessel 
 and a very small 
 lymphatic called a 
 lacteal. Since the 
 
 FIG. 114. To show the structure of the -ii- thirklv 
 
 wall of the small intestine, v, villi, and g, glands V11J LK1 ^ 
 
 of the mucous membrane ; c, circular muscle 
 layer ; I, longitudinal muscle layer ; p, peri- 
 toneum, or serous coat. 
 
 placed as to cover 
 the entire mucous 
 coat of the intestine 
 like the pile on a piece of velvet, the absorbing surface is 
 enormously increased. 
 
 The Support of the Intestine. The abdominal cavity, 
 or the portion of the large cavity of the trunk below the 
 diaphragm, has, like the thoracic cavity, a lining to prevent 
 friction. This membranous lining is called the peritoneum, 
 and like the pleura, it is double. It covers up the wall of 
 the cavity all around, lining it like a thin sheet, until it 
 reaches the place under the diaphragm where the esophagus 
 
The Digestion of Food 
 
 171 
 
 and larger blood vessels (aorta and vena cava) enter, where 
 it is reflected and courses downward, enveloping the stomach 
 and other digestive organs. It penetrates between them 
 by means of foldings and turnings, thus assisting to hold 
 them in place. The largest fold of all is called the great 
 omentum and covers the small intestine. The peritoneum 
 surrounding the intestines is called the mesentery. It is fan- 
 shaped and its 
 contracted part is 
 attached to the 
 spinal column for 
 a firm support. 
 The alimentary 
 canal, beginning 
 with the stomach, 
 may be said, 
 therefore, to have 
 a fourth layer, or 
 covering, the peri- 
 toneum. 
 
 The mesentery, 
 which surrounds 
 the intestines, is 
 attached to the 
 back wall of the 
 abdominal cav- 
 ity. It assists in holding them up in place. This support 
 is dependent upon and is assisted by the abdominal muscles 
 in front. People who stand with a relaxed, protruding 
 abdominal wall, lack the support which they should receive 
 from the abdominal muscles. There is a consequent falling 
 down of these organs. Such a condition is known by the 
 name viceroptosis (dropping of the viscera). Constipation 
 is a frequent accompanying condition, due to interference 
 with the circulation in the intestines. It is very important, 
 
 FIG. 115. Showing how improper posture favors 
 viceroptosis ; the mesentery is stretched and the 
 circulation to the loop of intestine is lessened. 
 
172 Healthful Living 
 
 therefore, to stand and walk with the abdominal wall held 
 in (Figs. 115, 93) and to exercise these muscles by partici- 
 pating in sports, games, athletics, and dancing. 
 
 The Digestive Fluids. The digestive fluids that enter 
 the small intestines are the pancreatic juice from the 
 pancreas, the intestinal juice from the small intestinal 
 glands (Fig. 114), and the bile from the liver. The bile 
 will be discussed later in consideration of the liver. At 
 present we will study the other two juices that come into 
 the small intestine. 
 
 (a) The pancreatic juice. The pancreas, or sweet- 
 bread, is flat, narrow, and about six inches long. It lies be- 
 hind the stomach, and tapers toward the left, ending above 
 the left kidney. Its shape has been compared to a dog's 
 tongue, and like the root of the tongue, it bends downward 
 at its broader end, where its duct leaves it and joins the bile 
 duct just before emptying into the duodenum. Its internal 
 structure resembles the salivary gland. The amount of 
 digestion accomplished in the small intestine exceeds that 
 in any other division of the canal, and the pancreas is the 
 most active and powerful of all the glands. Its secretion, 
 the pancreatic juice, is alkaline, and contains three enzymes, 
 one of which (amylopsin) is hardly to be distinguished from 
 the ptyalin of the saliva, and continues the digestion of the 
 starchy food ; another (enterokinase) joins with the trypsino- 
 gen of the intestinal juice and forms trypsin. Trypsin has 
 an action similar to pepsin, and digests protein; while the 
 third (lipase) begins the digestion of an important class of 
 foods, the fats, which have not heretofore come in contact 
 with a digestive fluid that could act upon anything more 
 than the protein envelopes of the fat cells. 
 
 Two definite changes occur in the digestion of fat. At 
 an early stage a physical change occurs and the fat is broken 
 up into minute globules. This favors the second stage, but 
 in itself is not a digestive act, because they are only in a 
 
The Digestion of Food 173 
 
 state of fine division and no chemical change has occurred. 
 Such globules, floating in a liquid, form what is called 
 an emulsion. Milk is an emulsion of cream. It is the 
 cream in sweet milk that gives it the white appearance, 
 for the globules of fat reflect the light. When it is 
 churned these minute particles touch and adhere, forming 
 butter. The chemical change is a splitting of the fat 
 molecule by the action of the enzyme, lipase, producing 
 fatty acids and glycerin. These chemical substances are 
 absorbed by the intestinal walls and passed into the lacteals 
 and blood stream. 
 
 (6) The intestinal juice. Besides the two large glands, 
 the pancreas and liver, there are a great number of very small 
 glands (Fig. 114) which furnish a digestive fluid to the in- 
 testine. The intestinal glands are scattered throughout the 
 lining membrane, and their secretion is called the intestinal 
 juice. This juice contains : 
 
 (1) Enterokinase, which activates* the trypsinogen from 
 the pancreas, forming trypsiri. 
 
 (2) Erepsin, which splits peptones received from the gastric 
 digestion. 
 
 (3) Maltase, invertase, and lactase, which split disac- 
 chrides into monosacchrides as described under the para- 
 graphs on enzymes. These enzymes are often called invert- 
 ing enzymes. 
 
 Absorption from the Small Intestine. The fats are 
 absorbed by the lymphatic system. Many minute lym- 
 phatics called lacteals (Fig. 116) are found in the villi of 
 the intestines, and the epithelial cells of the mucous lining 
 take up the fat and transmit it, slightly changed, to these 
 lacteals, which unite one to another and empty into the 
 thoracic duct. The thoracic duct empties into the sub- 
 clavian veins under the left clavicle. The fats thus pass 
 into the blood stream. 
 
 The sugars and proteins are carried by the portal circu- 
 
i 7 4 
 
 Healthful Living 
 
 lation to the liver. In this organ the sugars are changed to 
 glucose and stored until needed by the muscles. The protein 
 is passed and serves to build new tissue. In two different 
 ways, therefore, do the digested food elements reach the 
 main circulation. This provision resembles in a way the 
 means of travel for people on the earth. Some go by one 
 
 FIG. 116. Diagram of villus, with enlarged section showing 
 minute structure. 
 
 road and others by another. Some may go from New York 
 to Boston by rail and others may take the boat. The result 
 of the journey is the same they reach Boston. The 
 mineral matter is taken into the blood through the intestinal 
 loops and apparently in the same way that we account for 
 the passage of the digested protein and carbohydrates. This 
 passage of these elements through an animal membrane at 
 
The Digestion of Food 
 
 Co/or? 
 
 one time was explained according to the law of osmosis, 1 
 but it is now believed to be accomplished by. specific se- 
 cretory power of the intestinal cells. In other words be- 
 cause the intestinal cells are intestinal cells, they are able to 
 do this. They differ in this respect from epithelial cells 
 in other parts of the body. 
 
 The large intestine (or colon). The large intestine 
 is about five feet long. Its walls are drawn into pouches, 
 or puckers, by 
 bands of muscles 
 running length- 
 wise along it. 
 The small intes- 
 tine joins it in the 
 lower part of the 
 abdomen on the 
 right side (Fig. 
 117). The junc- 
 tion is not at the 
 end of the large in- 
 testine but above 
 the end. The part 
 below the junc- 
 tion is called the 
 caecum. Attached 
 to the caecum is a 
 small tube called 
 
 the vermiform appendix. Above the juncture the large 
 intestine is called the colon. The ascending colon runs up 
 along the right side nearly to the waist. It is then called 
 the transverse colon, and it comes forward and crosses just 
 
 1 Osmosis. "Whenever two solutions of different concentrations are 
 separated by a membrane which is permeable to water, there will be a flow 
 of water through the membrane in the direction of the greater concentra- 
 tion." This means that the solution that has the greatest concentration 
 of substances in it will exert a greater force on the weaker solution. 
 
 Cecum 
 
 FIG. 117. The valve between the small and 
 large intestine ; opening of small intestine and 
 appendix. Why is the valve called ileocaecal? 
 
176 
 
 Healthful Living 
 
 in front of the lower line of the stomach. It then retreats 
 to the rear wall and passes downward, being now called the 
 descending colon. Near the left hip it makes a double bend 
 called the sigmoid flexure (from sigma, the Greek letter S). 
 The nine inches remaining are without the pouched appear- 
 ance, the walls being smooth; this part is without bends 
 and is therefore called the rectum (from Latin rectus, 
 straight) . 
 
 Absorption in the large intestine is very active and its 
 contents soon lose their fluidity. Although it is mostly the 
 
 watery portion 
 that is absorbed, 
 any digested food 
 that may have 
 escaped absorp- 
 tion in the small 
 intestine is ab- 
 sorbed by the 
 colon. How sav- 
 ing and econom- 
 ical the body is ! 
 All the undigested 
 and indigestible 
 food gathers in 
 the sigmoid flex- 
 ure, and descends 
 at intervals into 
 the rectum, from 
 which it should be 
 evacuated at regu- 
 lar intervals. 
 
 Appendicitis. 
 The vermiform 
 appendix (worm- 
 like appendage) 
 
 FIG. 118. Abdominal viscera displayed so as 
 to show the portal vein carrying the blood from 
 the viscera to the liver. /, liver ; g, gall bladder ; 
 s, stomach, and d, duodenum these have been 
 divided from each other ; p, pancreas ; e, spleen ; 
 c, large intestine ; i, small intestine. The trans- 
 verse colon and part of the small intestine have 
 been removed. 
 
The Digestion of Food 177 
 
 is a part of the intestine which has degenerated in man 
 because of non-use. At one time it served a purpose; 
 today it serves none. Constipation, causing a clogging and 
 congestion of the appendix favors infection, and this organ 
 may become inflamed, causing appendicitis. Appendicitis 
 may prove fatal if the operation of removing the diseased 
 appendix is delayed too long. 
 
 Constipation. As the undigested part of the food passes 
 through the colon, it gradually loses its water and becomes 
 semi-solid. This is waste material and should be removed 
 daily by a regular habit of emptying the bowel. If the 
 bowel is allowed to remain filled with its waste contents, 
 there occurs absorption of poisons from this mass of waste 
 material. These poisons taken into the blood (Fig. 118) 
 and carried throughout the body, cause headache, lassitude, 
 weakness, and other disorders. 
 
 The Use of Foods in Constipation. There are many 
 causes of constipation but it is generally recognized that im- 
 proper selection of food may play an important part in the 
 production of the disturbance. For this reason it is of 
 value to know the foods that are laxative* from those that 
 are constipating and to use this knowledge with reference 
 to the selection of proper foods. All do not need a choice 
 of laxative food and no rule can be made for all people. 
 Food must be sele'cted with reference to the individual's 
 
 need. 
 
 LAXATIVE CONSTIPATING 
 
 1. Whole wheat and graham 1. White flour bread, hot 
 
 flour products, such as Pastry made with lard and 
 
 bread, crackers, gems, baking powder prepara- 
 
 biscuits, mush tions 
 
 Cake and custard puddings 
 
 2. Fruits such as prunes, dried, 2. Meats 
 
 stewed peaches, dried, Salted, dried and smoked 
 
 stewed fresh fruits of all meats 
 
 kinds Poultry 
 
 Salted and dried fish 
 
178 Healthful Living 
 
 LAXATIVE CONSTIPATING 
 
 3. Vegetables 3. Vegetables 
 
 Beets Beans, dried 
 
 Celery 
 Corn 
 
 Cauliflower 4. Cereals 
 
 Onions Rice 
 
 Peas, green Farina 
 
 Rhubarb 
 Spinach 
 
 Squash . 5. Miscellaneous 
 
 Cheese 
 
 4. Meats Cocoa and chocolate 
 
 Wild game, as rabbit, Milk, boiled 
 
 duck, pigeon, quail, deer, Tea 
 
 etc. Coffee substitutes made of 
 Liver wheat, corn and barley 
 
 5. Oysters 
 
 The liver. The liver is a large, heavy organ situated 
 on the right side of the body in the abdominal cavity and 
 lying up under the diaphragm. 
 
 With each inspiration the liver is pushed downward and 
 compressed by the diaphragm, the blood being forced out 
 toward the heart, and it fills again as soon as the breathing 
 muscles relax. This rhythmic compression is of great im- 
 portance in keeping the blood supply to the liver fresh and 
 pure, and preventing congestion in it. By tight clothing 
 the liver is often forced downward, out from the cover 
 of the ribs, and becomes permanently displaced. As a 
 result, other organs, lower in the abdomen and pelvis, 
 are crowded upon each other and also become dis- 
 placed. The circulation in the liver is diminished, and 
 hence its activity is decreased and the complexion loses its 
 freshness. 
 
 Pain in the right side after a rapid walk is due to con- 
 gestion of the liver with blood from the legs. What would 
 pain in the left side be due to ? 
 
The Digestion of Food 179 
 
 Anatomy of the liver. The liver is the largest gland in 
 the body. It is of a reddish brown color and weighs about 
 three and one half pounds. The upper and front surfaces 
 of the liver are very smooth and even. The under surface 
 is very irregular; it is here that the various vessels with 
 which this active organ is supplied make their entrance or 
 exit. Its connecting vessels, beside the lymphatics, are the 
 hepatic artery from the aorta, bringing pure blood; the 
 portal vein, bringing the digested food ; the hepatic vein, 
 carrying impure blood to the vena cava ; and the bile duct, 
 carrying the bile to the intestine. The bile duct, on its way 
 from the liver, gives off a side branch to the gall bladder. 
 This is a little dark green bag, in which the bile is stored 
 until it is required for digestion. 
 
 Circulation through the Liver, or Portal Circulation. 
 The portal vein and its function have been mentioned 
 (Fig. 118). When it enters the liver, it does a very unusual 
 thing ; in fact, it conducts itself as no other vein in the body 
 does, except some of the veins in the kidneys. It subdivides 
 into capillaries. Thus the portal vein (Latin, porta, a gate, 
 since it enters under a kind of archway) both begins and ends 
 in capillaries, for it begins in the capillaries of the digestive 
 tract and ends in the capillaries of the liver. After these 
 capillaries have passed in among the cells, they unite again 
 to form the hepatic veins, which go directly to the ascend- 
 ing vena cava. There is another large blood vessel in the 
 portal circulation. This is the hepatic artery, which enters 
 the liver directly from the aorta and supplies the liver cells 
 with arterial blood with which to repair themselves and carry 
 on their work. The capillaries from this artery unite with 
 those of the portal vein in forming the hepatic vein. A 
 cow's liver, cut in two, shows in places small gaping holes, 
 which are branches of the hepatic vein. 
 
 Microscopic Structure. If you examine the surface of 
 a piece of liver obtained from the butcher, you will find it 
 
180 Healthful Living 
 
 to be of a dark red color, and mottled over with little areas, 
 each measuring about one twentieth of an inch across. These 
 are the round lobules of the liver arranged around a branch 
 of the hepatic vein (Fig. 119). The capillaries of the portal 
 vein and hepatic artery and the branches of the bile duct 
 pass between these cells. Study carefully Figure 120, which 
 represents a segment of a lobule. When you understand 
 
 FIG. 119. Diagrammatic representation of two hepatic lobules. The 
 left-hand lobule is represented with the intralobular vein cut across : in 
 the right-hand one the section takes the course of the intralobular vein. 
 p, interlobular branches of the portal vein ; h, intralobular branches of the 
 hepatic veins ; s, sublobular vein ; c, capillaries of the lobules passing in- 
 wards. The arrows indicate the direction of the course of the blood. The 
 liver cells are represented in only one part of each lobule. Trace the blood 
 through these veins and name the vessels. 
 
 the circulation in a lobule, you will understand the circula- 
 tion in the entire liver, for a lobule is the liver in miniature. 
 Represent a lobule by a wagon wheel. The rim corresponds 
 to the capillaries of the portal vein and hepatic artery circu- 
 lating around the lobule. The spokes correspond to the 
 two kinds of capillaries united and on the way to the hepatic 
 vein in the hub, which will take the blood away from the 
 liver. Between the spokes are located the hard working 
 liver cells which get oxygen and food from the capillaries 
 in the spokes, and relieve themselves of impurities by means 
 of the finest bile ducts and lymphatic ducts, which begin 
 among the cells. 
 
The Digestion of Food 
 
 181 
 
 Functions of the liver. These cells of the liver have three 
 functions : (1) to secrete bile for digestion of food ; (2) to 
 store certain food elements after digestion, and (3) to ex- 
 crete from the blood certain waste substances. 
 
 Secretion Duties. The secretion of the liver is the bile. 
 It passes from the liver cells in a common duct that leads 
 to the intestine and gall 
 bladder. When the duct 
 is filled, the bile " backs 
 up " into the gall bladder, 
 where it is stored until 
 food is eaten, when it 
 enters the small intestine 
 close to the stomach. The 
 bile aids in the emulsifica- 
 tion of the fats. 
 
 The bile contains an 
 enzyme, amylase, which 
 has the same function as 
 the ptyalin of the saliva. 
 It digests starch. The bile 
 salts dissolve the fat acids, 
 promoting emulsification 
 and assisting in absorption 
 of fat. 
 
 Storehouse Duties. - 
 The sugars and protein 
 when digested are carried to the liver. The protein passes 
 through and goes on to the cells of the body. The sugar 
 remains in the liver until needed. 
 
 If a frog be dug up in the first part of its winter sleep, and 
 its liver be examined under the microscope, the cells will be 
 found swollen and full of glycogen, a substance stored up 
 for the winter needs of the frog. It is a carbohydrate ma- 
 terial resembling starch and made from digested sugar. 
 
 FIG. 120. Microscope, high power. 
 Diagram of a portion of a lobule of the 
 liver, showing the blood vessels and bile 
 ducts injected with fluid, p, interlobu- 
 lar branch of portal vein sending capil- 
 laries to open into h, intralobular branch 
 of the hepatic vein which lies in the 
 middle of the lobule ; b, a lymphatic ; 
 c, branch of hepatic artery ; d, branch 
 of bile duct ; into this (d) open the ducts 
 which lie between the liver cells. 
 
182 
 
 Healthful Living 
 
 The liver cells of a frog which has just come out in the spring 
 will be found shrunken and containing no glycogen (Fig. 121). 
 If a starving rabbit be killed and its liver cells examined, no 
 glycogen will be found, but the liver cells of a rabbit which 
 has recently been fed on turnips will be full of glycogen. If 
 two rabbits be well fed, one kept in a cage and the other 
 hunted around all day, much glycogen will be found in the 
 liver of the quiet rabbit, and very little in the liver of the 
 
 hunted one. The gly- 
 cogen stored up is used 
 during muscular work or 
 starvation. 
 
 The sugar absorbed 
 by the small intestine 
 reaches the liver through 
 
 FIG. 121. A, Liver cells of dog after a tne POrtal Vein. It is 
 
 thirty-six hours' fast; 5, also fourteen taken Up by the liver 
 hours after a full meal in the latter case -,-, -, -, -, , 
 
 swollen with glycogen. cells and changed into 
 
 granules of glycogen, to 
 
 be turned into sugar again during times of hunger and hard 
 work. Thus, only a small amount of sugar is allowed to 
 enter the circulation at one time, only 1^ ounces in every 
 1000 ounces of arterial blood. If more than this quantity 
 enters the blood, sugar passes out through the kidneys. 
 
 Excretion Duties. The excretory function of the liver 
 is important. As the blood containing the food passes 
 through it, waste substances in the blood from the tissues, 
 or poisons that may be in the food, are destroyed and the 
 products resulting from the destruction are sent out of the 
 body by either of two routes ; by way of the bile duct and 
 alimentary canal or by way of the blood vessels and kidneys. 
 All the blood in the body passes through it once every three 
 or four minutes, and as it passes it is purified. The waste 
 products resulting from the work done in the body are made 
 more soluble, so that they can be carried through the kidneys. 
 
The Digestion of Food 183 
 
 The yellow color of the bile is due to a pigment resulting 
 from the destruction in the liver of wornout red corpuscles. 
 The bile is partly an excretory product, but such is the econ- 
 omy of the system that it serves to aid digestion, and to 
 keep the alimentary canal in an aseptic condition. A man 
 could not smoke were it not for the liver. This organ takes 
 up the nicotine, if not too great in amount, and destroys it. 
 If one drinks alcohol, the liver endeavors to oxidize it and 
 get rid of it, so that the body may not suffer harm and in- 
 jury from it and usually the liver of a habitual drinker is 
 crippled or destroyed by its long struggle with alcohol. 
 
 A man would live many yea* s longer than he does if he 
 were not all the time producing waste products in his body 
 by his ordinary activities. The excretory organs are taxed 
 to remove them. In the young child as it is growing and 
 developing, the skin is so active, the kidneys are so healthy, 
 and the liver is so vigorous, that the waste is all removed and 
 the blood is pure. That is why a healthy child has so sweet 
 a breath, such bright eyes, and so fair a skin. When he 
 becomes older it is different. The same is true of a dog; 
 the puppy's breath is pure, its body is clean, so that it may 
 lie in a lady's lap or on a sofa and leave no unpleasant odor. 
 But when he is old, the dog becomes so offensive that he 
 has to be driven out of the house. The strong odor results 
 from the accumulation of waste substances in the body. 
 
 Urea is the chief waste product which results from the 
 breaking down of protein, and it is believed that the nitroge- 
 nous urea is formed by the liver. An excess of protein, 
 such as lean meat and cheese, in the diet, produces an in- 
 creased excretion of urea through the kidneys. It is ob- 
 vious that excess of food and lack of exercise may lead to the 
 disturbance of liver function. Such disturbance may be 
 relieved by a spare diet and vigorous exercise. The poor, 
 overworked liver should not be blamed, however, nor the 
 statement made that " the liver is not acting." At the very 
 
184 
 
 Healthful Living 
 
The Digestion of Food 185 
 
 time the complaint is made, the skin and eyes may be yellow, 
 showing the presence of too great a quantity of bile, which is 
 a product of the activity of the liver. 
 
 Functional disturbance of the liver may result from three 
 causes : (1) The first and most usual form is caused by 
 fermentation and other forms of indigestion, and by the 
 poisonous products therefrom entering the blood. (2) Stop- 
 page of the chief bile duct because of congestion, which ex- 
 tends to it from the stomach. This congestion is caused 
 by irritation of undigested food; (3) The liver cells and 
 ducts may become choked up from excessive food. 
 
 The waste products from food elements. When the 
 foods are oxidized in the body there are several products of 
 oxidation called waste products. The starches and sugars, 
 the fats and oils, when oxidized, give rise to water and carbon 
 dioxide. The protein gives rise to various products, of which 
 the most important are urea, uric acid, and creatin. These 
 are excreted by the kidneys. There are also found, in the 
 excretion of the kidneys, small quantities of phosphate and 
 sulphate of calcium, sodium, and potassium. Urea is a 
 substance of great importance, as it is the most abundant 
 nitrogenous waste substance produced by the processes of 
 action and growth in the cells of the body. ' Carbon dioxide 
 leaves the body through the lungs, and water leaves it 
 through the lungs, kidneys, and skin. 
 
 If a man were to live all day in a small chamber placed 
 upon very delicate platform scales, he would find that he 
 lost weight every second of his existence except when taking 
 food, and more rapidly at some times than at others, the 
 amount. of loss depending upon the activity of his body. 
 The loss of weight occurs through the excretions which the 
 man gives off. At average temperature of the air and average 
 activity of his body, the day's loss to be replaced by food 
 eaten, water drunk, and air breathed, would be about as 
 follows : 
 
i86 Healthful Living 
 
 From the large intestine ... 5 oz. excrement 
 From the skin . . . , . . . 25 oz. perspiration 
 
 From the kidneys 50 oz. excretion 
 
 From the lungs 35 oz. carbon dioxide and water 
 
 Total 115 oz. 
 
 The total loss is, then, nearly 8 pounds, three fourths of 
 which is water (nearly 6 pounds) . The remainder, except the 
 5 ounces of excrement, consists of those waste materials 
 (solid or gaseous) which result from the breaking down of 
 the active living protoplasm into simple chemical sub- 
 stances, through the process of oxidation. This amounts 
 to 27^- ounces and is apportioned as follows : perspiration, 
 J- ounce of salts, and a trace of urea ; the kidney secretion, 
 1 ounce of salts and 1-J ounces of urea ; the lungs, 25 ounces 
 of carbon dioxide gas. 
 
 APPLIED PHYSIOLOGY 
 
 LABORATORY EXERCISES 
 
 Experiment 1. To study the intake of fluid by the body per day. 
 
 Material. Coordinate paper, record of the number of glasses 
 of fluid taken. 
 
 Method and observation. Estimate the number of ounces 
 of fluid taken by counting the number of glasses of water, milk, 
 soda, etc., taken in one day. The common tumbler or glass will 
 hold eight ounces. Continue this observation for one week. At 
 the end of that time, record on coordinate paper on the abscissa the 
 days, and on the ordinate the total ounces per day. Connect the 
 points by straight lines. This will give a graphic representation 
 of the fluid intake for one week. 
 
 If this experiment is performed in the warm weather, it will 
 be interesting to carry along with this record of the fluid intake, 
 the average temperature of the atmosphere on each day. If this 
 is done, record the temperature on the chart and observe any rela- 
 tionship that exists. 
 Experiment 2. To test food material for starch. 
 
 Material. Cornstarch, tincture of iodine, and test tubes, 
 
 Method and observation. 
 
The Digestion of Food 187 
 
 (a) Mix a small amount of starch and water in a test tube to 
 the consistency of a thin paste. Add a few drops of iodine to the 
 mixture. What is the result ? 
 
 (6) Add some water to a small part of a boiled potato. Mash 
 the potato in the water. Add a few drops of iodine. What is the 
 result ? Iodine gives a deep purple in the presence of starch. 
 Experiment 3. To test for sugar (glucose). 
 
 Material. Glucose, the Fehling copper and the Fehling alka- 
 line solutions, 1 test tubes, and Bunsen flame or alcohol lamp. 
 
 Method and observation. Dissolve some glucose in water in 
 a test tube. To this solution add equal parts separately of the 
 Fehling solutions and heat to boiling. The presence of glucose is 
 determined by the change of the solution to a brick red. 
 Experiment 4. To test for fats and oils. 
 
 Material. Nuts or animal fats, white paper, ether. 
 
 Method and observation. (a) Rub the kernel of a nut with the 
 covering removed on a piece of paper. Hold the paper to the 
 light. The fat changes the light qualities of the paper. (6) Mash 
 the kernel of a nut in a dish and add ten cubic centimeters of ether. 
 Break up the kernel thoroughly and allow the preparation to stand 
 several minutes. Filter and save the nitrate, allowing it to 
 evaporate. 
 
 Ether extracts oil from substances and on evaporation leaves 
 the oil. 
 Experiment 5. To test for protein. 
 
 Material. White of egg (raw), nitric acid, ammonia, caustic 
 soda or potash, dilute copper sulphate, test tubes. 
 
 Method and observation (a) The Xanthoproteic reaction. 
 Place the white of the egg in a test tube and add nitric acid. Heat 
 gently to boiling. Cool and add ammonia. If protein is present, 
 a deep yellow color will appear on the addition of the ammonia. 
 (6) The Biuret reaction. Place the white of an egg in a test tube 
 and add two centimeters of the caustic soda. Then add a few 
 drops of the dilute copper sulphate solution, being careful to avoid 
 excess. If protein is present, a purple color will appear. A blue 
 color without any red is a negative test. 
 
 1 The Fehling copper solution is made by adding 35 grams of copper 
 sulphate (CuSOO to 500 c.c. of water; the alkaline solution by adding 160 
 grams of sodium hydroxide (Na(OH) 2 ) and 173 grams of Rochelle salt to 
 500 c.c. of water. 
 
1 88 Healthful Living 
 
 GLOSSARY 
 
 Absorption. The process by which nourishing material is taken 
 up by the body through the mucous membrane of the ali- 
 mentary tract. 
 
 Activates. To make active and to induce therein activity. 
 
 Alimentary canal. The digestive tract or canal along which 
 passes the aliment from which the body absorbs nourishing 
 material. 
 
 Chyme. The partly digested food as it passes from the stomach 
 into the small intestine to be converted into chyle. From 
 the Greek word, chymos, meaning juice. 
 
 Epiglottis. A small leaflike structure above the glottis. The 
 glottis is the name given to the upper end of the larynx. 
 
 Hydrochloric acid. A colorless, corrosive compound (HC1). It 
 occurs in the gastric juice in .3 to .5 per cent. 
 
 Laxative. A substance which stimulates the action of the in- 
 testines. It acts by increasing peristaltic action. 
 
 Neutralize. To render inert, incapable of further action. Acids 
 neutralize alkalis, and vice versa. 
 
 Peristalsis. The wavelike contraction that passes over the 
 intestines and stomach due to the contraction of the circular 
 and longitudinal muscle fibers. 
 
 Pharynx. The back part of the mouth. The cavity from which 
 goes the air through the larynx, trachea, and bronchi to the 
 lungs, and food and drink through the esophagus to the 
 stomach. 
 
 Pylorus. The gateway between the stomach and small intes- 
 tine. 
 
 Rheumatism. A condition in the body caused by disease-pro- 
 ducing organisms. These get into the blood and attack the 
 membranes of the joints and heart valves. The entry is 
 most often made through the cavities of teeth or infected 
 tonsils. The disease is not caused by uric acid. 
 
 Tonsil. A small lymphatic gland on each side of the mouth at the 
 entrance to the pharynx. 
 
 Uvula. The tiplike structure hanging down from the margin 
 of the soft palate at the margin of the pharynx. 
 
 Villus. A small finger-like projection from the mucous membrane 
 of the small intestine. The plural form is villi. 
 
CHAPTER XI 
 THE HYGIENE OF DIGESTION 
 
 I. Digestion, and Health. 
 II. Digestion and Environment. 
 
 III. Hobbies about Nutrition. 
 
 Hot water 
 Raw food 
 No condiments 
 Vegetarianism 
 No breakfast 
 
 IV. Man's Original Food Resources and How They Have Been 
 
 Enlarged. 
 
 V. Present-day Sources of Food. 
 Nuts 
 
 Pods or legumes Milk, cheese, and eggs 
 
 Fruits Grains 
 
 Meats Vegetables 
 
 VI. Patent Medicines. 
 VII. Shall we drink water at meals? 
 VIII. General Rules Modified by Individual Needs. 
 Indigestion 
 
 Two ways out of a difficulty 
 IX. Cooking. 
 Meats 
 Cereals 
 Vegetables 
 Eggs 
 
 X. The Fireless Cooker. 
 XI. Times for Eating. 
 
 Exercise in relation to eating 
 
 Digestion and health. A wit once said that if he had 
 been consulted at the creation of the world, he would have 
 
 189 
 
190 Healthful Living 
 
 made good health " catching " instead of disease. Obser- 
 vations show that happiness, industry, health, faith, and 
 other of the strong elements that make up life are more 
 contagious than misery, idleness, sickness, worry, and the 
 other weak elements that tend to destroy life. Fear causes 
 a tightening of the muscles and a waste of energy, as well as 
 oppressed breathing and a lack of oxygen. Courage brings 
 calm, full breathing which purifies the blood, and a steady 
 and economical use of the muscles which saves the vital 
 energy. A brave and cheerful visitor can inspire an ailing 
 friend and assist in his recovery. A happy, unselfish teacher 
 or pupil can dispel worry or gloom, and impart strength and 
 increased power for work to the whole school. The body 
 tends to health and not to disease. The dyspeptics * that we 
 see have been able to break down their health only after 
 long-continued attacks upon it, and outrages many times 
 repeated. Fresh air brings health, and forces its way into 
 the home to bring it, but the dyspeptic made every attempt 
 to keep it out. Sunshine brings health, but he shut himself 
 up in a stuffy ill-lighted office, a slave to dollars or to fame. 
 He curtained the sunshine out from the home to protect the 
 carpets and hangings from fading. Exercise brings health, 
 but the promptings to stir about, to walk, to run, or to work 
 with the hands, were repressed until the impulses ceased. 
 When activity was lessened, the appetite for food diminished, 
 but instead of following the prompting of nature, he sprinkled 
 more salt and pepper and other condiments upon the food, 
 that he might eat with an unnatural appetite. 
 
 By keeping up these artificial ways for months and years, 
 he at last succeeded in breaking down his health. It took 
 more perseverance to weaken the body than it will take to 
 make it strong again. There must be a return to sensible 
 ways of living with a reasonable trust in the inherent tend- 
 ency of the cells to restore soundness when given a chance. 
 If, however, he commits the folly of thinking that months 
 
The Hygiene of Digestion 191 
 
 are not needed for recovery, but that disease brought on by 
 months or years of wrong living can be cured in a few days 
 by taking magical drugs and patent medicines, he will in- 
 jure himself still more and probably lose his chance of re- 
 covering sound health. 
 
 Digestion and environment. It is known that the race 
 originally did not dwell in houses, and had few tools or cook- 
 ing utensils. Man probably first lived in the tropics and 
 subsisted upon the fruits which ripened in the never-ending 
 summer, and, as he migrated to the colder climates, sub- 
 sisted upon the results of the chase. That individual who 
 refused to peel his apples because, as he said, Adam had no 
 pocket knife, and slept with his windows open because Adam 
 had no house, had a right principle in view. If his teeth 
 were as sound as the teeth of primitive man, and his habit 
 of mastication as thorough, fruit skins would be an aid to 
 digestion. 
 
 Man possesses a stomach intended to digest the pure food 
 of the forest, obtained by activity in the open air. If a man 
 eats plain food and leads an active life, his appetite is a 
 perfect guide. If he does not, it is unsafe to trust to the 
 appetite alone, for the reason that he lives under conditions 
 unlike those for which this instinct was built up. A cow's 
 appetite is a certain guide to her among poisonous plants 
 and berries, yet she will eat a bucket of paint and harm her- 
 self ; the bucket of paint is beyond the range of her inherited 
 habits. Even if man's instincts had their early strength, 
 they could hardly guide him among the many food concoc- 
 tions and preparations undreamed of by primitive man. We 
 can train our taste into wrong ways, and we can likewise 
 train it into right ways and into liking food that we know 
 is wholesome. 
 
 It is found that returning to natural habits by going on 
 camping, hunting, and fishing trips is one of the most ef- 
 fective hygienic measures for the restoration of health. 
 
192 Healthful Living 
 
 Hobbies about nutrition. The subject of food and di- 
 gestion is a more complicated one than that of exercise or 
 breathing, and common sense is required to master it. 
 Therefore, more persons fail to master it, and allow their 
 minds to come to rest on some one fact or view of the subject 
 and so become' extremists. 
 
 Hot water. Some would cure every digestive ill by 
 means of water. Their belief is " water internally, ex- 
 ternally, and eternally." They sometimes drink it as hot 
 as it can be borne, yet hot water is very relaxing to the walls 
 of the stomach and weakens the flow of the gastric juice. 
 This extreme belief arose from the fact that hot water re- 
 moves the mucus from a stomach suffering from catarrh (or 
 congestion*) and diminishes the activity of the gastric glands 
 if too much acid is being secreted. 
 
 Raw food. Some persons have a fad called the raw food 
 doctrine, and eat no cooked foods. They should consider 
 that man's digestive organs are not as vigorous now as they 
 were ages ago, before he learned the use of fire. This fad 
 is a reaction from bad cooking. Cooked vegetables are more 
 likely to ferment in a weak stomach than raw vegetables. 
 The thorough chewing required by raw food is an advantage 
 to digestion. 
 
 No condiments. Some persons will not have condiments 
 or any kind of seasoning, not even salt, in their foods. This 
 is because many cooks destroy the natural flavors of the 
 food by bad cookery and hide the result by high seasoning. 
 There are many delicate and delicious flavors of grains, 
 fruits, and fresh vegetables that a natural appetite takes 
 pleasure in ; but because of long use of badly cooked and 
 highly seasoned foods the sense of taste in many persons 
 has become so depraved and dull that they have only five 
 kinds of taste left : the taste for grease, salt, pepper, vinegar, 
 and sugar. Their dull nerves require everything to be very 
 salty or peppery or sweet or greasy or sour. 
 
The Hygiene of Digestion 193 
 
 Vegetarianism. Some people have an aversion to eating 
 animal food but will eat vegetable food only. In develop- 
 ment, animal and plant came from the same source and life 
 in each differs only in degree. It is known that animal 
 protein is absolutely necessary for health. Pellagra, a very 
 serious disease producing marked changes in the nervous 
 system, results from the exclusion of certain essential animal 
 food elements. Most " vegetarians " are not vegetarians 
 at all. They are only " no meat eaters/' because they eat 
 eggs, butter, and milk and these are all animal food. 
 
 Those with whom meat does not agree, or who for humane 
 scruples, or other causes, adopt a vegetarian diet, sometimes 
 fall into serious error. If fruits and nuts are not freely used, 
 but the diet is confined to grains and green vegetables, a 
 large excess of starch is consumed, and the diet is very bulky 
 in spite of the fact that it is greatly lacking in fat and protein. 
 Persons who do not eat meat should replace the protein of 
 meat with that of nuts, cheese, beans, and peas, and employ 
 fat in the form of nuts, cream, milk, eggs, and butter. 
 
 No breakfast. Those who eat no breakfast, make up 
 in amount at the other two meals. Instead of taking three 
 meals to eat the food necessary for them, they eat it in two. 
 It is more hygienic to eat three small meals than two large 
 ones. Moreover, one can do better work in the morning after 
 a good breakfast. A good breakfast might include prunes, 
 milk, rolls, and a boiled egg. The practice of eating some 
 mushy cereal loaded with fruit and covered with cream and 
 sugar is not to be recommended. Cooked cereal, such as 
 oatmeal, eaten with a little butter on it is a desirable form 
 of breakfast food. 
 
 Man's original food resources and how they have been 
 enlarged. Cuvier, Owen, Huxley, and other comparative 
 anatomists agree that man was originally frugivorous; he 
 ate tree fruit, both nuts and fleshy fruits. Tree fruits con- 
 tain all the four chemical classes of foods, proteins, fats, 
 
194 Healthful Living 
 
 carbohydrates, and minerals. The present sources of his 
 food, besides the original nuts and fruits, are flesh, grains, 
 herbs, and he has added them to his dietary probably in the 
 order named above. In the warm regions of the earth, the 
 banana, plantain, mango, orange, and cocoanut trees bear 
 their luscious fruit the year round. But the multiplication 
 of the race and perhaps times of drought and famine led 
 man to use the food stored up in the flesh of other animals 
 which had obtained it from grass and herbs. This necessity 
 doubly increased with migration to colder climates. In the 
 frigid zones the inhabitants live very largely on animal food. 
 They consume immense quantities of blubber, or the fat of 
 certain animals, such as the whale, the walrus, and the seal. 
 This kind of diet, by sustaining the necessary bodily heat, 
 enables these people to withstand the intense cold to which 
 they are subjected. 
 
 Grains in their natural state are too small and collecting 
 them was too tedious before the time of that long-forgotten 
 genius who first thought of cultivating them in order to im- 
 prove them. Fruits and grains belong to the seed part 
 of the plant. The coarser woody leaves and stem and roots 
 were probably not added to man's food until the art of cook- 
 ing was much advanced. The degree of digestibility seems 
 to coincide in most persons with the order of adoption of the 
 classes of foods by the race. If one leads a sedentary life, 
 or his digestion becomes impaired, the weedy, fibrous vege- 
 tables should be the first to be discarded from the diet, while 
 flesh and fruits seem to furnish the main substance for in- 
 valids even after grains and starches prove hard to digest. 
 
 Present-day sources of food. We have learned that 
 man's digestive tract has developed with reference to plain 
 food gathered by his own physical efforts. Man's food to-day 
 both in its form and its method of production has under- 
 gone remarkable changes. Many articles are brought from 
 lands far away and land transportation makes it very easy 
 
The Hygiene of Digestion 195 
 
 to eat in Maine what has been grown in California. The 
 city man may buy all his food in a shop and never in all his 
 life produce actually one article of food. Of course, he pro- 
 duces in other ways. It is necessary that he make up in 
 other ways for the lack of physical exercise that is one of the 
 advantages gained from tilling the ground. 
 
 Nuts. Nuts are the most concentrated and nutritious 
 of all foods. Beefsteak is three fourths water, while nuts 
 are less than one fourth water. Nuts are how many times 
 as nutritious as beefsteak? This refers to the nut "meats " 
 or kernels. Nuts may be said to consist of one half fat, 
 one fourth protein, and the remaining one fourth, water 
 and mineral. The fat, unlike that of butter, oil, and fat 
 meat, is emulsified* in nuts, and does not need to be 
 divided up before absorption by the lacteals in the small in- 
 testine. Their density encourages the habit of thorough 
 chewing. Nuts are made up of little cells, each of which 
 has its proportion of proteins, fat, and dextrin,* a kind of 
 sugar. The small boy climbs the tree and gathers the nuts, 
 cracks and eats them, and digests them thoroughly. The 
 man stays in his office, has some one else to gather them, 
 masticates less thoroughly, and he may find them less di- 
 gestible, especially if he always eats a full meal before tak- 
 ing the nuts. Green or rancid nuts are not digestible. Nuts 
 should be eaten during the meal the same as meat. They 
 are not easily digestible raw. Persons who usually eat nuts 
 after they have already eaten too much, consider them very 
 indigestible. They are not digestible if eaten between meals, 
 or if not thoroughly chewed. 
 
 Pods or legumes. Pods or legumes resemble nuts very 
 closely in chemical composition, but they require long and 
 thorough cooking. Their seed coats, or hulls, consist of 
 cellulose* or woody fiber, which may well be removed. The 
 hulls can be loosened by soaking them in cold water before 
 they are cooked. Beans and peas have been called the lean 
 
196 Healthful Living 
 
 meat of the vegetable kingdom, and they contain a high 
 percentage of protein. 
 
 Fruits. Fruits have four important advantages : 
 (1) Their agreeable flavors are a natural and healthy stimulus 
 to the digestion. (2) They contain vegetable acids (either 
 citric, malic, or tartaric) that are perfect germicides,* and are 
 of value in purifying the alimentary canal. (Fruits have 
 almost no protein.) (3) They contain very valuable mineral 
 salts that are of highest use to the blood and tissues. (4) The 
 carbohydrate in ripe fruits is all in the form of levulose or 
 fruit sugar, which is absorbed without digestion. With 
 these advantages there is the disadvantage that fruits are 
 largely water, so that the nutriment they contain is very 
 scant, except in the case of grapes, bananas, and olives. 
 
 The proverb that fruit is golden at breakfast, silver at 
 noon, and lead at night, is not true. Fruit is golden at all 
 times, if it is sound and ripe, and if the stomach is not already 
 filled with food. Fruit juices are valuable as restoratives 
 to health, since they tax the digestive organs very little and 
 are quickly assimilated. Since germs will not grow in fruit 
 juices, a fruit diet for several meals will disinfect the ali- 
 mentary canal and ward off a " bilious " attack. Juicy 
 apples, pears, lemonade, orangeade, pomegranateade, ripe 
 peaches, etc., are pleasanter than medicines. 
 
 Meat. Protein is the principal food substance in meat. 
 Beef contains the largest amount among the common meats, 
 and pork the least. The fat of meat is also of great impor- 
 tance : fat is abundant in pork. Meat that is salted and 
 smoked, or dried, or prepared in any way so that germs will 
 not grow in it, can be kept for a long time, but its digesti- 
 bility is greatly impaired. This is because its fibers have 
 been hardened so that the gastric juice cannot readily pene- 
 trate them. Meat which has much connective tissue is 
 tough; the most tender and digestible of meats consist 
 almost wholly of muscular tissue and fat. 
 
The Hygiene of Digestion 197 
 
 Experiments show that ordinarily one fifth of the protein 
 in vegetable food passes through the intestine undigested 
 and unabsorbed, and is thus wasted, while only one thirtieth 
 of the protein in meat escapes digestion. A pound of fat 
 requires three times as much oxygen in its oxidation as a 
 pound of sugar, and therefore yields three times the heat and 
 energy. The digestibility of fat is increased by the fact that 
 it ferments with difficulty, while sugar and starch ferment 
 more easily. Meat should be thoroughly cooked to avoid the 
 danger of diseases from Trichina spiralis and other parasites. 
 
 Meat Extracts. Researches concerning the nutritive 
 value of meat extracts show that in none of them is a large 
 quantity of food concentrated in a small bulk as the public 
 is led to believe. A glass of milk contains far more nourish- 
 ment than a cup of beef tea. The best way to get the nour- 
 ishment out of a steak is to eat it. The beef extract contains 
 but a fraction of the protein in beef, and all of the nitrogenous 
 waste material allied to urea. The most nutritious part of 
 the beef is not soluble, but the excretory part of the meat 
 is soluble, and this is found in the beef tea or beef extract. 
 This extract throws work upon the kidneys and is harmful. 
 The part of the beef that has most value is thrown away in 
 making the extract. Many lives are no doubt annually 
 sacrificed by starvation through the popular faith in beef 
 tea as a concentrated and nourishing food. Beef tea and 
 meat juice can be used as flavoring agents with other food 
 since they stimulate the secretion of pepsin, but they should 
 not be regarded as real food. 
 
 By drying meat it can be reduced to one fourth its weight 
 (since it is three fourths water). Thus 100 pounds of beef 
 can be reduced to 25 pounds and sold in a form useful to 
 travelers. The meat will keep fresh as long as it is kept dry. 
 Water is added to the meat when it is cooked. 
 
 Milk, cheese, and eggs. Cow's milk is suited for calves, 
 and was intended to be obtained by sucking and to be swal- 
 
1 98 Healthful Living 
 
 lowed gradually. It does not contain the right proportion 
 of food elements for infants and, therefore, must be modified 
 when fed to infants. The casein or protein part is coagu- 
 lated in flakes by the rennin, and when a child vomits coagu- 
 lated milk, it does not mean that it is suffering from indi- 
 gestion, although it may sometimes mean that it is being 
 overfed. The tendency of milk to produce constipation in 
 some persons may be explained as follows : when adults 
 drink sweet milk rapidly, especially toward the end of the 
 meal, when much acid is present in the stomach, the acid 
 coagulates the casein into large lumps of curd, which may 
 seriously disturb the digestion, for milk was not intended 'to 
 be drunk rapidly. Heat retards the production of acid in 
 the gastric juice and increases the secretion of rennin. If 
 taken before meals, hot and slowly, milk will agree with 
 those who have found it to produce indigestion. Butter- 
 milk is one of the most digestible of foods. 
 
 Cheese is a concentrated food, and is one of the cheapest 
 although not one of the most digestible forms of protein. 
 
 Eggs are valuable food and in proportion to their value 
 are cheaper than meat. They are very digestible when 
 properly cooked. Eggs should not be fried nor boiled hard. 
 
 Grains. Nearly all the starch of our food is supplied 
 by grains. They also contain from 8 to 15 per cent of a 
 protein called gluten. The chief grains are wheat, oats, 
 barley, corn, rice, buckwheat. The more of gluten there is 
 in grain, the more gluey or sticky its flour will be. Sticky 
 flour will retain the bubbles of gas formed from baking- 
 powders or by the growth of the yeast plant. Wheat has 
 much gluten, and its flour makes very light bread. Corn 
 meal has not enough gluten to make it very sticky, and corn 
 bread will not rise well. Corn contains more fat than any 
 other grain, yellow corn containing more fat than white corn. 
 Wheat is richer in starch and protein than any other grain. 
 If cooked several hours, the starch of grains is so thoroughly 
 
The Hygiene of Digestion 199 
 
 dextrinized that it is changed to sugar almost instantly 
 when brought in contact with the saliva. Grains may be 
 cooked during the preceding meal and the cooking finished 
 in preparing the meal at which they are to be eaten. If 
 oatmeal and other mushes are sticky, it shows the presence 
 of half -cooked starch. Rice and oatmeal may be first 
 browned in the oven and afterward steamed. Toast and 
 brown crust are almost as digestible as ripe fruit and may 
 be eaten by invalids. 
 
 Three Kinds of Flour. There are three ways of grinding 
 wheat to make flour : (1) Using the whole grain and the 
 husk which incloses the grain. This makes graham flour. 
 (2) By using the whole of the grain. This makes whole 
 wheat flour. (3) By rejecting the outer and darker portion 
 of the grain, thus losing part of the gluten and retaining all 
 of the starch. This makes the ordinary flour. 
 
 Graham flour is most stimulating to peristalsis in the canal. 
 Its large amount of waste matter furnishes something for 
 the intestine to contract upon, and thus sweep all waste 
 matter on and out of the body, contributing to the cleanliness 
 of the canal. It sometimes causes congestion in irritable 
 stomachs. Sometimes flour which is merely dark with dirt 
 is sold for graham flour. The whole wheat flour is stimu- 
 lating to the canal but is not irritating. 
 
 White flour is used more extensively because it makes white 
 bread. This is judging the food by its appearance and not 
 by its food value. It is believed by some that the whole 
 wheat flour is more desirable as it contains salts, food ele- 
 ments, and waste material that are very important. Nations 
 in time of war, when economy is necessary, use the whole of 
 the wheat in the milling of flour. Nations in time of peace 
 and plenty use white flour. Nations at peace should not be 
 wasteful, and, moreover, they should use at all times foods 
 which will make the healthiest and most efficient citizens. 
 
 In the Great War, Germany, on account of the shortage 
 
soo Healthful Living 
 
 of wheat, was compelled to use other cereals and even potatoes 
 in the making of flour. As early as December 1, 1914, the 
 Bundesrat issued a decree that no bread should be baked 
 of pure wheat flour. The war flour prescribed " must con- 
 tain at least ten parts, by weight, of rye flour to ninety parts 
 of wheat flour. Rye flour must contain at least five parts 
 potato flour to ninety-five parts of rye flour. The baker 
 may increase the portion of potato flour, but bread with 
 more than five parts potato flour must be marked with the 
 letter "K" (Kartoffel, potato). If there are more than 
 twenty parts potato flour, the figure must be added to the 
 " K." The term bread includes loaves, rolls, etc." 
 
 Vegetables. Root vegetables and tubers, such as potatoes, 
 sweet potatoes, and turnips, contain a small percentage of 
 starch. But vegetables in general consist almost entirely 
 of water and woody fiber (cellulose). This is especially 
 true of green vegetables, or those which consist of the leafy 
 part of the plant. But green vegetables contain an iron- 
 bearing albumin, which is of great value to the blood and 
 tissues. This form of albumin is easily destroyed in the 
 intestine before it reaches the blood, if fermentation takes 
 place. As some leafy vegetables are more likely to ferment 
 if cooked, there is an advantage in eating them raw. Iron 
 and valuable mineral salts are thus obtained. 
 
 Cellulose. Cellulose has the same chemical composition 
 as starch. It forms the cell walls and woody fibers of plants, 
 and is hardly digested at all by man ; hence, starch requires 
 cooking to burst the cellulose envelopes of the starch grains. 
 Cellulose and water are the chief constituents of grass, and 
 of greens, cabbage, and other fibrous vegetables. It forms 
 the fibers in watermelons, which also contain cane sugar, the 
 sweetest of the sugars. The woody skins of beans and peas 
 are cellulose. Hence, many find the legumes more digestible 
 in a pure*e, or cooked with the skins removed. Cellulose is 
 the natural stimulant to peristalsis and activity of the canal. 
 
The Hygiene of Digestion 201 
 
 Cattle digest cellulose, and with them it takes the place of 
 starch. 
 
 Patent medicines. There are a considerable number of 
 people who violate laws of health and then seek to escape 
 from the results by taking a pill or a tonic*. The digestion 
 of food is not a mysterious act and it will proceed in a satis- 
 factory manner, if simple rules of living are adhered to. 
 Errors in diet can be atoned for, not by the taking of patent 
 medicines, but by learning the art of living, and of this 
 lesson, spare diet, hard work, exercise, and recreation form 
 the first and last page. 
 
 Health of the body comes by living in a hygienic manner. 
 Health will come and will stay only when the body is cared 
 for properly and given sufficient exercise and recreation. 
 
 Shall we drink water at meals. Food should be chewed 
 until it is broken into fine parts and thoroughly mixed with 
 the saliva. Thorough mastication is essential. It not only 
 prepares the food better for digestion in the stomach but it 
 also prevents overeating. 
 
 Drink should not be used to wash the food down the 
 esophagus. The food should be chewed and mixed with the 
 saliva until it can be swallowed easily. If one desires to 
 drink water at meals and follows the right method there is 
 no harm in so doing, but the habit of using liquid to wash 
 the food down is easily acquired and one should be careful 
 not to form it. 
 
 General rules modified by individual needs. The 
 student readily sees that the question of individual needs 
 is important. There is truth in the old adage, " What is 
 one man's meat is another man's poison." No cast-iron 
 rules can be laid down for any one's life. Common sense can 
 never be dispensed with. Persons with moderate powers 
 of observation find by experience what is best, and they 
 should have will power enough to adhere to what they find 
 is best for them, although opposite ideas may be presented 
 
202 Healthful Living 
 
 to them as the only correct way, by persons of narrow views. 
 What is enough for one is a surplus for another. Sex, age, 
 occupation, and heredity, each has its influence on diet. 
 The wear and tear of an active body requires a class of food 
 which to one of sedentary occupation would be a burden. 
 Exercise lights the fire that burns up the refuse of the body, 
 and thus it increases the appetite and strengthens the di- 
 gestion. 
 
 Indigestion. If a person confines himself closely with 
 brain work and takes no exercise whatever, he may not 
 digest his food well, but he need not think his digestive 
 organs unsound, and begin dieting himself. He should take 
 more exercise, and by better habits of life stir up his circula- 
 tion, use the food stored in the cells, and they will become 
 hungry for more, and digestion will be perfect. There is a 
 saying, " You can lead a horse to water, but you can't make 
 him drink." So you may put food in the alimentary canal, 
 but you cannot make the cells assimilate it, although, by 
 high seasoning, you may have aroused an appetite for it. 
 The fact that such food is not digested does not mean that 
 the digestion is weak, it means only that too much food and 
 too many condiments have been used. 
 
 Two ways out of a difficulty. Exercise is the best way 
 out of digestive troubles ; yet, if a student or office man is 
 under the delusion that he " just simply has not time " to 
 take plenty of exercise, he may partly meet the difficulty 
 and keep his brain clear by an abstemious diet. 
 
 Cooking. The cooking of food should involve more than 
 applying heat sufficient to burst the envelope of cellulose 
 or coagulate the protein. It should convert it into a di- 
 gestible condition. This is essential, but it is also important 
 to cook it in such a way that when served it will be pleasing 
 because the digestion of the food is dependent, as you re- 
 member, upon psychic stimuli. In this connection, it should 
 be stated that the frying pan is an undesirable utensil for any 
 
The Hygiene of Digestion 203 
 
 household. Roasting, baking, stewing, boiling, broiling, are 
 good methods, but frying should be abolished. 
 
 Meat. Meat should be roasted by putting it into a hot 
 .oven at first, to form a crust to keep in the juices, then lower- 
 ing the temperature of the oven to prevent drying out and 
 hardening. When broiling meat, it should be turned over 
 every ten seconds to send the juices back and prevent their 
 escape, thus broiling the meat in the heat of its own juices. 
 Meat should not be salted until after it has been cooked, for 
 salt draws the juices out. 
 
 Cereals. You learned that the starch of fruit, when it 
 ripened, was turned to sugar. Ordinary cooking bursts the 
 cells of starch in the grain and begins the transformation 
 into dextrin, a substance intermediate between starch and 
 sugar. This is a great help, for the saliva does not act upon 
 raw starch, and the pancreatic juice acts only slightly and 
 after several hours' delay. Cooking that amounts to little 
 more than moistening and heating the starch, is a disad- 
 vantage, and makes it more likely to ferment than if eaten 
 raw ; but thorough cooking adds greatly to the digestibility 
 of starch. Oatmeal, cracked wheat, and other grain foods 
 should be cooked at least 40 minutes. Rice should be washed 
 in cold water in a colander after cooking. After washing, 
 the rice may be reheated by steaming. It is then very 
 palatable. 
 
 Bread is best if made of whole-wheat flour. It should be 
 cooked in a slow oven, so that the inside of the loaf may be 
 well baked. The loaves should be made small and not touch- 
 ing, so that there may be much crust. Crust (1) cleans the 
 teeth like a brush and makes them healthy from use ; (2) it 
 increases flow of saliva by its dryness and the longer 
 chewing required ; (3) it is more easily digested than the 
 crumb, or white portion, as it resembles sugar. Beaten 
 bread is the most digestible, like the hoe cake and other 
 unleavened breads. Yeast bread comes next in digest}* 
 
204 Healthful Living 
 
 bility. Baking powders containing alum, and soda, if not 
 thoroughly neutralized by sour buttermilk, are injurious, 
 even to the healthy. 
 
 Yeast belongs to the class of plants called fungi, that can 
 live in darkness, and have neither leaves nor blossom. Most 
 plants get nourishment from the soil, air, and water, but 
 yeast and other fungi derive their sustenance from vegetable 
 or animal matter in process of decomposition. Yeast plants 
 are microscopic cells of oval shape, and, like other plants, 
 require food in liquid form. They cannot absorb dry or 
 solid food. Their most suitable food is sugar. The flour 
 of wheat contains starch, a small amount of which is con- 
 verted into sugar by the diastase which lies next the, bran. 
 Yeast grows best at a temperature of from 70 to 80. A 
 slow growth at a lower temperature favors the development 
 of other micro-organisms which make the yeast unhealthy 
 and produce bad flavors. With a high temperature its 
 growth is rapid and of extremely short duration. 
 
 Fermentation * may go through several stages ; in the first 
 stage, or alcoholic fermentation, the yeast decomposes the 
 sugar, splitting it into alcohol and carbon dioxid gas. This 
 is the stage for bread-making, the gas causing the bread to 
 rise. In the second stage, or vinegar fermentation, alcohol 
 is changed to acetic acid the acid in vinegar. Hard wheat 
 has more gluten than other wheat, and the bubbles formed 
 in its flour will not break easily. Why does bread from such 
 wheat rise well ? Why is bread set in a warm place to rise ? 
 Why does it " fall " if left to stand too long? Under what 
 conditions does bread made from yeast become sour ? Why 
 does bread set to rise in a cold place sometimes have a bad 
 flavor? 
 
 Vegetables. Irish potatoes, to become mealy instead of 
 soggy, should be put into boiling water, and, after they are 
 cooked, the water should be poured off, and the pot should 
 be set on the back of the stove for the potatoes to dry. 
 
The Hygiene of Digestion 205 
 
 Roasting them in the oven with their skins on also retains 
 their flavor and makes them mealy. 
 
 Onions are better if cooked, to drive off the acrid, irri- 
 tating oil. Raw cabbage, which is water and cellulose, 
 is treated by the stomach as a foreign substance, and sent 
 promptly to the intestine ; but the stomach attempts to 
 digest boiled cabbage, and it remains there several hours. 
 Peanuts are nutritious and digestible if properly prepared. 
 Boiling water should be poured over the raw peanuts so that 
 the skins can be removed. They should simmer on the stove 
 for hours until they can be easily pressed through a colander. 
 This with the addition of a little salt is a palatable food. 
 Raw and roasted peanuts are not easy to digest. 
 
 Eggs. Eggs should be cooked by placing them in boiling 
 water and taking the pot off the stove. They cook while 
 the water is cooling, and the albumin is jellied but not 
 hardened. 
 
 The fireless cooker. Cooking meat and vegetables by 
 placing them in a closed cabinet and providing heat in the 
 form of heated stone is a desirable method of cooking. Meats 
 are made more tender. Vegetables can be cooked thoroughly 
 and yet they will retain their form. A fireless cooker makes 
 housework easier and for this reason alone it should be part 
 of the furnishing of a home. 
 
 Times for eating. Different nations have various habits 
 of eating. The number of meals varies from two to five, or 
 even eight, meals daily. Such facts show the adaptability 
 of the stomach to different habits. It is an organ which 
 readily forms habits, and is greatly benefited by regularity. 
 If a person avoids disturbing the stomach between meals 
 and allows it needed rest, both appetite and digestion are 
 promoted. Three meals a day seem to be needed, especially 
 by hard workers. The Greeks ate two meals a day, and 
 developed the most beautiful and perfect bodies in the world, 
 as shown by the statues left by them. 
 
206 Healthful Living 
 
 Exercise in relation to eating. Very active exercise tends 
 to hinder the work of the stomach, but facilitates that of the 
 intestines. For a half hour after a full meal, hard work of 
 every kind should be avoided, but hard work an hour or two 
 later will aid digestion. The arrangement of the meals 
 must take into account the other habits of the individual. 
 For example, if three meals are eaten in twenty-four hours, 
 the last ought to be the lightest ; but, as business is trans- 
 acted in large cities, a business man can hardly find time 
 for a hearty meal in the middle of the day. Hence he does 
 right in eating a lunch at noon, and having the heartiest 
 meal come in the evening, when the day's labor is over and 
 there is time to relax. If he takes the principal meal in the 
 latter part of the day, he should not eat ,very heartily the 
 next morning or during business hours ; to do so would 
 surfeit the system. Late suppers should not be eaten, as 
 they prevent sound sleep. The lower animals may lie down 
 in the shade and sleep after eating, but it is only for a short 
 nap. A nap of ten minutes, just long enough to bring about 
 relaxation, is often of benefit after a meal. During sleep 
 the heart beats less frequently and with less force; the 
 lungs are less active ; the brain nearly ceases its activities ; 
 the muscles relax and become motionless ; peristalsis and 
 secretion in the alimentary canal become slow, and the di- 
 gestive organs should have rest. If a person is troubled 
 with a too great flow of blood to the brain, some light, di- 
 gestible article of food taken just before retiring may bring 
 sleep ; but it should be taken simply to regulate the circu- 
 lation, and should be so digestible as to give little work to 
 the stomach. A farmer will do a better afternoon's work 
 if he will rest for half an hour after the noon meal. 
 
 The rule that every individual must be a law unto himself 
 may be abused by those who consult their appetites alone 
 without reference to their common sense. If we believe 
 that regularity in eating is desirable, the stomach and 
 
The Hygiene of Digestion 207 
 
 appetite can be trained to it, although if one is used to eating 
 at all times and between meals, the desire to do so may re- 
 main for a time. An appetite for whisky is an acquired one, 
 and is not an evidence of a normal and healthy demand. 
 Emaciated and half -starved persons may suffer from want of 
 appetite, but it may be a sign that they should increase the 
 activity of other organs, as the muscles, not that they should 
 follow the guidance of appetite and eat insufficient food. 
 
 A good and healthy appetite comes from the expenditure of 
 energy and rebuilding of the tissues, and a person with such 
 an appetite enjoys best the simple foods that will best give 
 energy and build tissue. The best pleasures of eating are 
 for those who have appetites of this kind, not for the epicure 
 or glutton. This is only one example of the general truth 
 that mere pleasure seekers do not have the best pleasures ; 
 but they enjoy life best whose living is complete, all the 
 duties and pleasures of life being given their proper place. 
 
 APPLIED PHYSIOLOGY 
 
 Exercise I 
 
 1. How do you explain the difference in the way a dog eats 
 meat and a horse eats grain? (Compare with question 8.) 
 
 2. Clothing and shelter for man or beast economize what 
 kind of food? 
 
 3. Why does wheat bread rise better than corn bread? 
 
 4. Why is corn bread one of the most fattening of grain foods ? 
 
 5. Why is it that you can tell best about the digestibility of 
 bread while you are slicing it ? 
 
 6. What kind of persons would not find it well to take a long 
 walk before breakfast ? 
 
 7. Why are late suppers unhealthf ul ? 
 
 8. Why should bread remain longer in the mouth than meat? 
 
 9. In snowballing what is the appearance of the hands when 
 they itch from cold? Why does ice- water not satisfy the thirst, 
 but often produces a craving to drink more water? 
 
 10. Why is it more difficult to swallow a small pill than a large 
 one? 
 
208 Healthful Living 
 
 Exercise II 
 
 11. When is hunger a safe guide? 
 
 12. Why does not fat meat taste as well in summer as in winter ? 
 
 13. Name organs which receive more benefit from the blood 
 than they give to it. 
 
 14. Name organs which give greater benefits to the blood than 
 they receive from it. 
 
 15. Why should pork be thoroughly cooked ? 
 
 16. What necessary step in preparing salt meat to be cooked 
 lessens its nutritive value ? 
 
 17. Should biscuits, having a yellow tint or dark spots due to 
 soda, be eaten? 
 
 18. Why, during an epidemic, are those who have used alcohol 
 as a beverage usually the first to be attacked ? 
 
 19. What is the effect of alcohol upon albuminous substances? 
 
 20. Explain how it is that when people speak of an inactive 
 liver they usually mean an overworked one. 
 
 Exercise III 
 
 21. How does the possession of a gall bladder furnish evidence 
 that man should have meal times and not eat at all times ? 
 
 22. Who attains greater success in life and true happiness, the 
 man who makes millions of dollars but loses his health by close 
 application to money making, and has to live on gruels and soups, 
 and does not have sound sleep, or the man who makes a living and 
 no more, sleeps soundly, enjoys his food, and has strong nerves? 
 Which do you regard as a truly successful man? Which does 
 public opinion regard as more successful? 
 
 23. Do you buy more wood (cellulose) when you buy beans or 
 when you buy nuts? 
 
 24. Do you buy more water when you buy bread or when you 
 buy meat ? 
 
 25. Which is true, the original saying: "Stuff a cold, and 
 you will have to starve a fever," or the modern way of stating it? 
 
 26. Why is soda sometimes good medicine to neutralize a sour 
 stomach, and very bad for digestion if eaten in bread? 
 
 27. What advantage in digestibility may a hot biscuit have over 
 a loaf of stale bread? Vice versa? 
 
 28. Some physiologists hold that the eating of much meat causes 
 an irritable temper. Does your observation of others or your 
 personal experience confirm or disprove this ? 
 
The Hygiene of Digestion 209 
 
 29. Why do people who live in overheated rooms often have 
 poor appetites? 
 
 30. Why may the taking of prepared pepsin weaken the stom- 
 ach? 
 
 31. Why is there often an outbreak of colds when a warm moist 
 spell of weather succeeds several weeks of cold dry weather? 
 
 32. Explain how the stomach may be weakened by the eating 
 of predigested foods. 
 
 APPLIED PHYSIOLOGY 
 
 LABORATORY EXERCISES 
 
 Experiment 1. To study the changes which take place in the diges- 
 tion of starchy foods in the mouth. 
 
 Material. Crackers, Fehling solutions, test tubes. 
 
 Method and observation. (a) Test an unsweetened cracker 
 with Fehling solution for sugar. Note the result. (6) Test some 
 saliva with Fehling for sugar. Note the result, (c) Chew some 
 of the unsweetened cracker and test some of this chewed cracker 
 with Fehling. Note the result. 
 
 What conclusion would you draw from this one experiment as 
 regards the digestion of starch in the mouth of the experimenter? 
 With observation of other people what conclusion could be drawn 
 as regards such digestion in general ? 
 Experiment 2. To study cooking processes. 
 
 1. Try at home cooking rice and then washing it in a colander 
 and compare the result with that obtained by washing the rice 
 before cooking. The washing process removes the sticky gluten 
 that has been set free by the cooking process. 
 
 2. Notice the difference in the white (albumin) of a fried egg 
 and a boiled egg. 
 
 GLOSSARY 
 
 Cellulose. A substance that forms the chief material of the 
 
 structure of plants. 
 Coagulation. The process of solidification of a liquid. This 
 
 may be accomplished by means of heat or by acids. When 
 
 an egg is cooked the protein of the white coagulates. 
 Congestion. An abnormal and excessive accumulation of blood 
 
 in the vessels of an organ or a part, 
 p 
 
2io Healthful Living 
 
 Dextrin. A brownish- white compound with the chemical formula 
 (Ci 2 H 2 oOio). It is derived from starches by a process of remov- 
 ing two molecules of water. It is one of the steps in the 
 digestion of starches. 
 
 Dyspeptic. One who has dyspepsia. Dyspepsia is an old term to 
 denote difficult and painful digestion. To-day the term "in- 
 digestion " is used and is more acceptable. In one respect the 
 older term is satisfactory. It comes from Greek origin, dys 
 meaning bad, and pepto cook. Bad cooking is often the cause 
 of indigestion. 
 
 Emulsify. To convert into an emulsion. 
 
 Emulsion. A liquid mixture in which a fat or oil is suspended 
 in minute globules. Milk is an emulsion. The butter fat 
 is suspended in such minute globules that they do not appear 
 in fresh milk. After milk has " stood " for some time, the 
 fat will rise to the top because it is lighter than the other ele- 
 ments in the milk. 
 
 Fermentation. A chemical decomposition of an organic com- 
 pound usually induced by living organisms. The action of 
 enzymes in causing chemical change in digestion is also spoken 
 of as fermentation. 
 
 Germicide. A substance capable of killing germs (Bacteria). 
 Could be called bacteriocide. 
 
 Tonic. A medicine or regimen having the power to invigorate 
 and build up the body. Medicines chiefly by improving the 
 appetite. Fresh air, out-door exercise, change of activity, 
 sleep are the best tonics for the body. 
 
CHAPTER XII 
 THE CIRCULATION OF THE BLOOD 
 
 I. How the Circulation of Blood Serves the Body. 
 II. The Nature of Circulation. 
 
 III. The Composition of the Blood. 
 
 The work of the red corpuscles 
 The work of the white corpuscles 
 The work of the plasma 
 
 IV. The Heart as a Pump. 
 
 How the heart works 
 The circulation traced 
 V. The Blood Vessels as Tubes. 
 Structure of the vessels 
 Arteries and veins compared 
 Adaptation of the vessels 
 VI. Blood Pressure. 
 
 How the pressure is measured 
 Modification of pressure and blood flow 
 Need for modification 
 VII. The Heart Rate. 
 
 How the circulation of blood serves the body. It will 
 be recalled that the tissues composing the body are made 
 up of cells ; that these cells are active and must have food ; 
 that the food for the cells is the nutritive food elements 
 (protein, fat, and carbohydrate) and the non-nutritive food 
 materials (water, and salts) ; that some of these substances 
 undergo slow combustion in the tissues ; that this combus- 
 tion or uniting with oxygen gives rise to carbon dioxide and 
 other waste substances. The blood which serves as the 
 vehicle for the transportation of food and the removal of 
 
212 
 
 Healthful Living 
 
 waste from the cells to the excretory organs, has other im- 
 portant functions. 
 
 It also serves in equalizing the temperature of the body. 
 The heat of the body is continually kept at a certain point 
 (98.6 F.) in health, by the blood vessels bringing to the sur- 
 face of the body the heated blood and allowing radiation of 
 this heat to occur. The blood also serves to protect the 
 body from infections by having in its plasma, substances 
 which protect the body. The blood also carries secretions 
 from internal glands which control growth and development. 
 The nature of circulation. To have a circulation, there 
 must be a fluid, a pump, and a system of tubes or pas- 
 sages through which the fluid is forced. In a city water 
 system, the fluid is the water, the power station provides 
 the pump, and the mains are the tubes. In the body the 
 fluid is the blood, the pump is the heart, and the tubes are 
 the arteries and veins. In studying the circulation, there- 
 fore, we must study the 
 blood, the heart, and the 
 blood vessels. 
 
 Composition of the 
 blood. When seen un- 
 der the microscope blood 
 no longer appears of a 
 uniform red color. It is 
 found to consist of a 
 clear, colorless liquid 
 called plasma,* in which 
 floats a multitude of 
 small bodies called cor- 
 puscles . * The corpuscles 
 
 themselves are seen to be of two kinds. By far the greater 
 number are round, yellow, and flattened, but a few, perhaps 
 one in four hundred, are round, white, and globular, and 
 larger than the yellow ones (Fig. 122). The yellow ones 
 
 FIG. 122. Blood cells, a, red corpus- 
 cles seen from the side ; b, red corpuscles, 
 seen on edge, are run together in rows 
 
 c, section through middle of red corpuscle 
 
 d, red corpuscle swollen with water 
 
 e, white corpuscles. 
 
The Circulation of the Blood 
 
 213 
 
 are called the red corpuscles, because the light shining 
 through a great number of them gives the blood a red color. 
 The white ones are called the white corpuscles. The follow- 
 ing presents in tabular form the elements making up the 
 blood : 
 
 f Red blood cells 
 
 [Cells \ (-lymphocytes* 
 
 [ White blood cells ( 
 
 [ leucocytes * 
 
 Blood 
 
 Water 90 per cent 
 
 
 f oxygen 
 
 
 Gases I carbon dioxide 
 
 
 [ nitrogen 
 
 
 f albumin 
 
 
 
 tein 1 S lobulin 
 
 
 
 I fibrinogen 
 
 Food 
 
 
 
 
 carbohydrate glucose 
 
 
 chlorides 
 
 ' sodium 
 
 Inorganic 
 
 carbonates 1 
 
 potassium 
 
 salts 
 
 sulphates f 
 
 calcium 
 
 
 phosphates j 
 
 magnesium 
 
 Plasma 
 
 Waste 
 
 products urea and uric acid 
 
 Protective 
 
 substances agglutinins, etc. 
 
 Growth 
 
 determiners hormones * 
 
 The work of the red corpuscles. The red corpuscles serve 
 to carry oxygen (Fig. 123). They contain a substance in 
 their protoplasm which has the power of combining chemically 
 with oxygen. This substance is haemoglobin. When the 
 red cell passes in the pulmonary vessels through the lungs 
 
214 
 
 Healthful Living 
 
 FIG. 123. a, human 
 blood corpuscles, side 
 and front view ; b, frog's 
 blood corpuscles, side 
 and front view. Both 
 are drawn to the same 
 scale. 
 
 the haemoglobin " takes up " oxygen in accordance with the 
 needs of the body. This is an important fact. When the 
 body has used oxygen in large amounts, 
 the red cells will be depleted and so will 
 take up more when they make their 
 next trip through the lungs. 
 
 The work of the white corpuscles. 
 The blood of healthy persons possesses 
 a certain power of destroying germs of 
 disease which may enter the body; this 
 is called its germicidal or germ-killing 
 power. The germs are minute one- 
 celled organisms to be seen only through 
 a powerful microscope. Some float in 
 air ; others are found in liquids or solids. 
 Most kinds of germs are not harmful to 
 man. For instance, there is a germ which gets into milk 
 and causes it to turn sour. The yeast germ, used in bread 
 making, is a microscopic one-celled plant which obtains its 
 nourishment from sugar. 
 
 The germicidal power of the blood rests in part, at least, 
 in the white corpuscles. When the flesh is cut, or when 
 bacteria lodge in the tissues, these little scavengers may be 
 seen collecting at the danger point in great numbers ; some 
 of the germs are devoured bodily by the white corpuscles ; 
 others are killed probably by substances in the plasma which 
 were formed by these little guardians. In no way is the 
 provision for our welfare better shown than by the existence 
 of these corpuscles (Fig. 124). 
 
 The work of the plasma. That the blood may flow readily 
 through every little tube, it must be liquid, hence a large 
 part of it is water. The water is important also as a solvent 
 for the salts, waste products, food, and other substances 
 carried. The gases present in the blood are nitrogen, oxygen, 
 and carbon dioxide. The nitrogen is inert and is only ab- 
 
The Circulation of the Blood 
 
 sorbed physically. The oxygen is in chemical combination 
 with the haemoglobin of the red corpuscle. The carbon 
 dioxide which results from 
 combustion in the cells is 
 removed by the blood and 
 carried partly in chemical 
 combination with various 
 salts and partly in physical 
 solution in the plasma. The 
 food elements are all repre- 
 sented. The proteins are 
 albumin, globulin, and a 
 special protein concerned in 
 coagulation. 
 
 If some blood from an 
 animal is allowed to stand 
 in a vessel, it soon becomes 
 a red, jelly like mass. This 
 change is called coagulation. 
 If we let the coagulated 
 blood stand, it gradually ,-, 
 
 J FIG. 124. Migration of white cor- 
 Separates into two parts, puscles through the walls of a vein. 
 
 a light yellow liquid called They are sh n ** different stages of 
 
 . * migration. The red corpuscles remain 
 
 Serum, which IS Colored by in the stream. 
 
 a few blood cells, and a 
 
 semi-solid mass called the clot, which contains most of the 
 
 cells together with some threadlike fibers (Fig. 125). A 
 
 FIG. 125. Diagram to illustrate the process of coagulation. A, fresh 
 (corpuscles and plasma) ; B, coagulating (formation of fibrin) ; C, coagu- 
 lated (clot and serum) . Plasma minus fibrinogen equals serum. Corpuscles 
 plus fibrin equal clot. 
 
2i6 Healthful Living 
 
 substance called fibrinogen was in solution in the plasma. 
 It has solidified into fibers, called fibrin * which, by entangling 
 the red and white corpuscles, caused the formation of the 
 clot. The portion of the plasma that remains liquid is com- 
 posed of the water with all the other elements in solution. 
 The carbohydrate element is represented by glucose. The 
 fats vary in amount. During digestion the fat content is 
 higher than in the intervals between digestion. The salts of 
 the plasma are mainly salts of sodium. There are some potas- 
 sium salts in the corpuscles, but the inorganic matter is repre- 
 sented largely by the salts in the liquid portion of the blood. 
 
 The waste products which result from the breaking down 
 of chemical compounds in the production of energy are 
 present in the blood on their way to the organs of elimina- 
 tion, the kidneys, skin, and lungs. Urea* and uric acid,* which 
 arise mainly from protein oxidation, carbon dioxide, which 
 comes from the breaking down of carbohydrate, and fat are 
 the chief substances. 
 
 The protective substances in the plasma serve to kill 
 bacteria. It is known that many diseases produce a con- 
 dition as an after effect that protects the individual ever 
 afterwards from that disease. Some of these substances act 
 separately and others in conjunction with the white cor- 
 puscles. According to their function, they have been given 
 names, such as bacteriolysins (to dissolve bacteria) , agglutinins * 
 (to produce a cluster), precipitins (to cause a precipitate), 
 opsonins (to prepare as food for). The last three are ap- 
 parently concerned more with making it possible for the 
 white corpuscles to attack the bacteria. 
 
 The growth determiners are substances produced by 
 glands in the body. The secretions are taken up by the 
 blood and control, in some way not clearly demonstrated, 
 the growth and development of the body. The glands pro- 
 ducing these secretions are thyroid, thymus, pituitary, 
 adrenal, pancreas, ovary, and testicle. 
 
The Circulation of the Blood 
 
 217 
 
 The heart as a pump. The organ which gives the push 
 or impulse to the blood and causes it to circulate in the tubes 
 or vessels is the heart (Fig. 126). The tubes that conduct 
 the blood away from the heart to the organs and tissues are 
 called arteries. The tubes through which it returns to the 
 heart are called veins. The very small tubes that take the 
 blood from the arteries to the veins where it begins its re- 
 turn journey are called capillaries. The blood must cir- 
 culate in order that it may go to the digestive organs to get 
 food, or to the lungs to get oxygen, and to all the tissues in 
 
 Supe. 
 
 FIG. 126. Diagrammatic section of heart. 
 
 order to distribute these things, and to carry away waste 
 materials to the organs that will free the body of them. Can 
 you see in your mind the dark color of a piece of beef and the 
 lighter color where a fresh cut is made? Blood going from 
 the lungs to the tissues is bright red, about the color of a 
 piece of new beef when the knife cuts into it. The blood 
 going from the tissues to the lungs is darker, about the color 
 of the outside of the piece of raw beef some time after it is 
 cut. 
 
 The heart is situated in the chest, between the two lungs. 
 It is a hollow muscle, and has the remarkable power of con- 
 tracting and relaxing itself with periodical regularity. The 
 
218 
 
 Healthful Living 
 
 movement of contraction is called the systole * ; the re- 
 laxation is called the diastole.* The period of systole is 
 the systolic phase ; the period of diastole is the diastolic 
 phase. 
 
 The hear-t is divided by a vertical partition into halves 
 (Fig. 127). The right half receives the dark blood from the 
 body and sends it to the lungs. The left half receives the 
 
 Aorta 
 
 Pu/monery 
 Artery 
 
 Superior^ 
 Vena Cava 
 
 Pulmonary 
 Veins 
 
 Jnferior 
 Vena Cave 
 
 Right Ventricle 
 
 Aorta 
 
 FIG. 127. Diagram to show the course of the blood through the heart. 
 The vessels containing impure blood are drawn darker than the others. 
 
 bright blood from the lungs and sends it to every part of 
 the body. Each half is also divided by a horizontal partition, 
 but unlike the vertical ones, these partitions are- pierced 
 with openings for communication. The heart, therefore, 
 contains four chambers; the two .upper ones are called 
 auricles, the two lower ones ventricles. The right auricle 
 communicates with the right ventricle just below it, and the 
 left auricle communicates with the left ventricle. 
 
The Circulation of the Blood 
 
 219 
 
 FIG. 128. The right 
 side of the heart. The 
 blood flowing through the 
 valve into the 
 
 How the heart works. From all parts of the body (ex- 
 
 cept the lungs) the blood arrives at the right auricle, dark 
 
 red in color, and charged with carbon 
 
 dioxide, a gas that is unfit for support- 
 
 ing life. The blood has come through 
 
 two large veins, the superior vena 
 
 cava, from the head, arms, etc. (Fig. 
 
 127), and the inferior vena cava, from 
 
 the lower parts of the body. The 
 
 first chamber of the heart that it 
 
 enters is the right auricle. The 
 
 auricle contracts and presses the 
 
 blood into the right ventricle (Fig. 
 
 128). It begins to squeeze together 
 
 just around the openings of the veins, 
 
 so that it closes their openings. The blood, owing to this, 
 
 cannot go back into the veins, but is forced into the ven- 
 
 tricle. The right ventricle, thus filled with blood, at once 
 begins to contract. The first effect of 
 the pressure thus produced is to force 
 blood behind the flaps of the tricuspid 
 valve, the valve between the auricle 
 and ventricle, consisting of three flaps 
 made of white fibrous tissue. The 
 blood behind the flaps brings the flaps 
 together and so blocks the way to the 
 auricle (Fig. 129). The contraction 
 of the ventricle goes on, and soon the 
 Wood presses hard enough upon the 
 semilunar valve to open it and go on 
 
 ^ the pulmonary artery (Fig . 129 ) . 
 
 the semilunar valve opens when the 
 pressure in the ventricle is greater than the pressure in the 
 pulmonary artery. 
 When the ventricle has emptied itself, it relaxes. The 
 
 FIG. 129. The blood 
 
 e o The 
 
 lungs. Tricuspid valve 
 
 closed, semilunar valves 
 
22O Healthful Living 
 
 semilunar valve is composed of three pockets, which the 
 swollen pulmonary artery fills with blood as soon as the 
 ventricle begins to relax. The pockets of the valve are thus 
 pressed together, and no blood flows back into the ventricle. 
 The auricle was relaxing while the ventricle was contracting, 
 and it is already filled with blood that has flowed in from the 
 veins. After a short pause, it again contracts ; and the 
 same action is repeated. More and more blood is thus 
 driven by the right ventricle through the semilunar valve 
 into the pulmonary artery, so that the blood which is al- 
 ready in the artery is sent on through the numerous small 
 branches and through the multitude of fine tubes called 
 capillaries, which go through every part of the lungs. 
 
 In the lungs the carbon dioxide passes into the air passages, 
 and the oxygen brought by the breath goes into the blood 
 of the capillaries, which changes in color to bright red. The 
 capillaries unite again to form the pulmonary veins, which 
 lead back to the heart. We thus see how the blood is sent 
 from the heart through the lungs and back to the heart. 
 How is the blood sent through the body and back to the 
 heart ? We shall find that this is done by the left side of the 
 heart; that the two ventricles, acting like pumps, work in 
 unison ; that, in fact, a wave of muscular contraction start- 
 ing at the top of the heart passes downward over both sides 
 of the heart at once, both auricles contracting at the same time 
 and then relaxing as the contraction passes to the ventricles. 
 
 As we learned, the pressure from the right ventricle keeps 
 the blood moving through the pulmonary artery, the capil- 
 laries of the lungs, and the pulmonary vein. It returns to the 
 heart again, and this time it enters the left auricle. When 
 the left auricle is full, it contracts and drives the blood 
 through a valve called the mitral valve, into the left ven- 
 tricle (Fig. 130). The left ventricle (at the same time with 
 its mate, the right ventricle) then contracts, forcing the 
 blood behind the flaps of the mitral valve, closing the way 
 
The Circulation of the Blood 
 
 221 
 
 back to the left auricle. The pressure of the ventricle opens 
 the semilunar valve in the mouth of the great aorta, which 
 is the large artery carrying the blood from the left ven- 
 tricle. The aorta takes the blood to every part of the body 
 
 FIG. 130. View of the orifices and valves of the heart from below, the 
 whole of the two ventricles being cut away, a, aorta ; b, pulmonary artery, 
 each with its three cups of the closed semilunar valves seen convex from 
 below ; opening between right auricle and right ventricle, surrounded by 
 three flaps of the tricuspid valve with chordae tendineae between them, to 
 which three cords are tied, taking the place of the papillary muscles, d, 
 opening between left auricle and left ventricle, with two flaps, of the mitral 
 valves and chordae tendinae, to which cords are tied. 
 
 This figure may be said to show the roof of the two ventricles, with the 
 two great valves, by which the blood enters the ventricles and the two great 
 valves by which it leaves them. All the openings of the ventricles are up- 
 ward. 
 
 except the lungs. It gives off smaller arteries, and the 
 division is repeated until arteries are supplied to every 
 organ and tissue. In the tissues the arteries empty into 
 smaller tubes called capillaries. The aorta, with its branches, 
 becomes distended with blood, and as more and more is 
 forced into it by the left ventricle at each heart beat, the 
 
222 
 
 Healthful Living 
 
 distention is kept up, and some of the blood already in the 
 aorta is forced along its branches, and the same pressure 
 
 forces it through the capillaries 
 and into the veins (Plates V 
 and VIII). 
 
 The blood flows slowly 
 through the capillaries and 
 performs its function of ex- 
 changing substances needed 
 for those used up. It next 
 goes into the veins on the 
 return journey to the heart, 
 where it enters the right 
 auricle again, which was our 
 starting place in this descrip- 
 tion (Fig. 131). 
 
 The circulation traced. The 
 blood comes from the tissues 
 through the veins and enters 
 the right auricle, goes through 
 the tricuspid valve into the 
 FIG. 131. Diagram illustrating ventricle, then through the 
 
 the circulation, a, right auricle ; . . , , , 
 
 semilunar valve it enters the 
 
 b, left auricle ; c, right ventricle ; 
 d, left ventricle ; e, vena cava 
 superior ; /, vena cava inferior ; 
 g, pulmonary arteries ; h, lungs ; 
 i, pulmonary veins ; j, aorta ; k, ali- 
 mentary canal ; I, liver ; ra, hepatic 
 artery ; n, portal vein ; o, hepatic 
 vein ; follow the arrows and see 
 whether you come around to the 
 starting point again. 
 
 the aorta by the semilunar 
 
 valve, thence to the capillaries of the system, thence to the 
 veins, and through them it returns to the heart, completing 
 the circulation. 
 
 Blood vessels as tubes. The blood tubes are built of 
 tissues so arranged that they provide the correct kind of 
 
 pulmonary artery. Travers- 
 ing the capillaries of the lungs, 
 it goes by the pulmonary 
 veins, to the left auricle, then 
 through the mitral valve to 
 the left ventricle, thence into 
 
The Circulation of the Blood 
 
 223 
 
 tube needed for the circulation of blood in the body. They 
 differ in their properties from galvanized pipe that is used 
 in water supply systems, and these differences are important. 
 
 FIG. 132. Transverse section of part of the wall of an artery, highly 
 magnified, a, epithelial (endothelial) layer, or inner coat ; b, muscular layer, 
 or middle coat ; c, outer coat, consisting of connective tissue. 
 
 In order to understand how the arteries, veins, and capil- 
 laries are adapted to their work, we will study their anatomy. 
 We shall find three kinds of 
 tissue (Fig. 132) used in their 
 construction, epithelial tissue 
 to prevent friction,* connective 
 tissue to give both strength and 
 elasticity, * and muscular tissue 
 to enable the vessels to change 
 in size. 
 
 Structure of the vessels. The 
 epithelial tissue forms the inner- 
 most layer of the vessels. The 
 endocardium or inner lining of 
 the heart is formed of this mem- 
 branous layer, and is continued 
 throughout the arteries, capil- FlG 133 . _ Epithelial cells 
 
 laries, and veins. In these forming the walls of capillaries, 
 vessels the inner mat is oallpH The nuclei and the outlines of 
 
 VtyOOV/lO* l/llt/ llllltyl L-V/dU Ife CdliL'd ,1 11 i ml f 
 
 the cells may be seen. The form- 
 the endothelmm. The epithe- ing of the thin tubular walls of 
 
 Hal Cells forming this Smooth ^e capillaries is one of the most 
 
 curious among the many wonder- 
 layer are thin and flat, and ful feats accomplished by the cells. 
 
224 
 
 Healthful Living 
 
 serve to diminish friction. The walls of the capillaries, the 
 smallest vessels, consist simply of this epithelial membrane 
 (Fig. 133). 
 
 The middle coat is muscular and is made up of the muscle 
 cells arranged in circular fashion. The muscle is more abun- 
 dant in the arteries than in the veins, but is present in both. 
 The outer coat is made of connective tissue. This 'layer 
 is outside of the muscular tissue, and forms the outer surface 
 of the artery. It contains both white fibers and yellow 
 
 elastic fibers 
 (Fig. 132). In 
 fact, some of the 
 yellow elastic 
 fibers (Fig. 132) 
 are found also in 
 the other coats. 
 The muscular 
 and connective 
 
 FIG. 134. An artery and corresponding vein cut . , 
 
 across. A, artery; B, vein; a, endothelial cells; tlSSUe layers be- 
 
 b, muscular coat ; c, connective tissue. Notice the come still thicker 
 
 nuclei of endothelial cells, and the greater amount of . . 
 
 muscular tissue in the artery. m the larger ar- 
 
 teries. So the 
 
 wall of an artery consists of three layers : (1) the endo- 
 thelium; (2) the muscular coat; (3) the connective tissue 
 coat on the outside (Figs. 132 and 134). The arteries are, 
 therefore, very firm and elastic, and do not collapse when 
 they are cut, but stand open, and the flow of blood through 
 them is unobstructed. The walls of the veins consist of the 
 same three layers. Their walls are not so thick as those 
 of the arteries, for the muscular and connective tissue layers 
 are much thinner (Fig. 134). When a vein is cut it col- 
 lapses, that is, the thin walls fall together, and the bleeding 
 is stopped unless the vein is large. 
 
 Arteries and veins compared. (If this is made a written 
 exercise, underline the words which you supply.) 
 
The Circulation of the Blood 225 
 
 Walls. The walls of the are very elastic, while the 
 
 walls of the are slightly elastic. The walls of the 
 
 are thicker and stiffer than the walls of the . It is 
 
 necessary that they should be so, because they must sustain 
 the of the . 
 
 Work of Each. The arteries take pure blood from the 
 to the , and impure blood from the to the 
 
 The veins take pure blood from the to the , and im- 
 pure blood from the to the . 
 
 Connections at Heart. The are connected with the 
 auricles. The are connected with the ventricles. 
 
 Rate of Flow. The blood flows more rapidly in the 
 
 Manner of Flow. The blood in the flows uniformly. 
 
 The blood in the flows . 
 
 Control of flow. The are abundantly supplied with 
 
 . The have none. 
 
 Location. The arteries as a general rule are located . 
 
 The veins are generally located . This adds to the 
 
 of the body. 
 
 Definitions. The arteries are tubes that carry blood 
 (both pure and impure) - - the . 
 
 The veins are tubes that carry blood (both pure and im- 
 pure) the . 
 
 Accidents. If an artery is cut, the pressure is to be ap- 
 plied the cut and the . If a vein is cut, the pres- 
 sure is to be applied the cut. A cut vein may be told 
 
 from a cut artery in the three following ways : 
 
 Adaptation of the vessels. The white fibers of the con- 
 nective tissue coat (Fig. 132) give strength and firmness to 
 the vessel, and the yellow elastic fibers give elasticity. The 
 muscular, or middle coat enables the arteries and veins to 
 change in size, and the inner, or endothelial layer gives 
 smoothness and prevents friction. Why are these three 
 properties necessary to blood vessels ? 
 Q 
 
226 Healthful Living 
 
 Elasticity of the Blood Vessels. The aorta and its 
 branches are full of blood all the time. When the left 
 ventricle with its great muscular walls contracts, the blood 
 cannot move forward into the narrow arteries and capil- 
 laries fast enough to make room for the new supply so sud- 
 denly sent out of the ventricle. Therefore, the aorta be- 
 comes more than full. If a cup is full, it cannot become 
 " fuller " ; not so with an artery. The yellow elastic fibers 
 of its connective tissue allow it to expand as a thin rubber 
 hose does under pressure. The first part of the aorta having 
 expanded to receive the incoming blood, the portion of the 
 aorta just ahead of the expanded portion is less tense, or 
 tight, so the stretched elastic fibers contract and force blood 
 into it, expanding it in turn. Thus a wave of expansion 
 travels along the blood vessel. It is, called the pulse and 
 may be most easily felt in the wrists and neck. The dis- 
 tended elastic walls exert pressure on the blood in the arteries, 
 and this presses some of the extra blood out of them into the 
 capillaries. As much blood as is being pressed on into the 
 capillaries is being thrown into the aorta by the beat of the 
 heart ; so that during life a distention is always kept up, 
 and the blood in the vessels is always under pressure. Al- 
 though the arteries may get rid of the additional distention 
 following each heart beat, there is a normal distention that 
 always remains. It has existed ever since life began, and 
 will remain until the heart ceases to beat. The pulse, there- 
 fore, is only an additional distention following the contrac- 
 tion of the ventricle. 
 
 You should not think that the muscular layer actively 
 contracts and helps to send along the pulse ; for the pulse is 
 simply the passive stretching and contracting of the elastic 
 tissue ; as a wave travels across a pond when a stone is 
 dropped into the water. The force of the pulse is furnished 
 by the heart. What, then, is the purpose of the muscular 
 layer in the arterial wall ? . 
 
The Circulation of the Blood 227 
 
 Use of the Muscular Coat. The body of an adult con- 
 tains about five quarts of blood. We have learned that the 
 blood supplies the substances needed for the activity of 
 each organ. If an organ is working, it needs more blood 
 than usual, and it is supplied by the other organs that are 
 at rest ; they get along with less blood for the time. The 
 muscular coat of the blood vessels makes this possible. This 
 coat is usually in a condition of slight contraction, but the 
 nerves controlling the muscular coat in the blood tubes of 
 the active organs may cease to act, thus allowing the muscu- 
 lar coat to relax and the blood tubes to enlarge under the 
 pressure from the heart, so that the active organs may ob- 
 tain the additional supply of blood needed. While this is 
 happening, part of the pressure in the blood tubes of the 
 inactive organs is relieved and they become smaller. If 
 cold air strikes the face, the nerves stimulate the muscular 
 coat of the blood tubes in the face to contract more strongly 
 than usual, and the face turns white. This driving of the 
 warm blood from the face saves heat to the body, which 
 would be lost if the warm blood remained in the skin. Thus 
 the amount of blood circulating in any organ is regulated 
 by means of the muscular coat of the blood vessels and of 
 the action of the nerves upon this coat. 
 
 Use of the Inner Coat. We learned that the inner coat 
 of the heart and blood vessels is made of epithelial tissue, 
 like that which forms the outer layer of the skin, and the 
 smooth lining of the mouth and other organs. This lining 
 membrane is very smooth and thus friction is lessened. The 
 friction, however, is inconsiderable in the large vessels ; but 
 in the smaller vessels it is greater ; and in the minute capil- 
 laries it becomes of very great importance. We see, there- 
 fore, why it is necessary to have this smooth coat in the 
 capillaries, although the muscular and connective coats are 
 not prolonged into them. It should be stated here that 
 although the extremely minute size of the capillary tubes 
 
228 Healthful Living 
 
 increases the friction and the pressure which the heart must 
 expend in sending the blood through them, yet their re- 
 sistance to the blood flow is lessened by their great capacity. 
 The united capacity of the capillaries is six hundred times 
 that of the blood arteries that supply them. In the capil- 
 laries the blood flows slowly like a river which flows into and 
 out of a lake. 
 
 Blood pressure.* The force with which the heart sends 
 the blood into the vessels and the resistance offered to the 
 flow produces a pressure in the arteries. This pressure is 
 greatest in the aorta and gradually decreases in the course 
 of the vessels until in the veins that come into the heart it 
 has fallen nearly to zero. This pressure in the arteries is 
 fluctuating. At each beat of the heart it is increased by the 
 push given by the volume of blood forced out of the left 
 ventricle, but as this wave of pressure passes toward the 
 capillaries it grows less just as the ripples on a lake will de- 
 crease in size from the point where a stone was thrown into 
 the water. This wave of pressure gradually decreases, until 
 in the capillaries the flow of blood is now constant, and 
 owing to the resistance the pressure has become less. After 
 passing through the capillaries, the pressure in the veins 
 continues to fall until it reaches the heart again. 
 
 We shall learn later how the contractions of the muscles 
 and their squeezing effect upon the veins passing through 
 or beneath them, aid the heart to move the blood; also 
 how the expansion and contraction of the lungs act as a 
 great pump ; and how these aids, together with changes of 
 posture, enable the blood to reach the heart again. If one 
 stands perfectly still for some time, the blood, owing to its 
 weight and the lack of pressure on the veins, slowly con- 
 gests in the veins in the lower part of the body, and the 
 consequences may be serious. 
 
 Hence the pressure is greatest in the arteries, less in the 
 capillaries, and least of all in the veins. 
 
The Circulation of the Blood 
 
 229 
 
 How the pressure is measured. This blood pressure, as 
 it is called, can be measured (Fig. 135) and it is found that 
 for normal adults it is 
 nearly constant. The 
 systolic pressure is that 
 pressure which exists dur- 
 ing the contraction of the 
 heart and is stated to be 
 from 110 to 120 m.m. of 
 mercury 1 ; the diastolic 
 pressure is that pressure 
 existing during the re- 
 laxation of the heart and 
 is found to be about 
 65 m.m. of mercury. It 
 has been found also that 
 whatever increases the 
 force of the heart's beat 
 will increase the blood 
 
 pressure and vice versa; 
 and whatever increases 
 the resistance to the flow 
 in the capillaries will in- 
 crease the blood pressure 
 and vice versa. 
 
 The blood pressure is an indication of health in the body 
 and hence it is measured to determine certain conditions. 
 The instrument used for measuring the pressure is called 
 a sphygmomanometer (Fig. 135) . 
 
 FIG. 135. Blood pressure machine 
 (sphygmomanometer) . This instrument 
 determines the force which exists within 
 the arteries under different conditions. 
 
 1 Blood pressure is usually measured in terms of millimeters of mercury. 
 This means that the force exerted in the blood vessel would support a unit 
 column of mercury of a certain height. The height in this case would be 
 110 to 120 m.m. The examination of college freshmen by Dr. Lee at Har- 
 vard, and my own examinations at the University of Cincinnati, indicate 
 that the normal is higher than the 120 m.m. usually given. It may be con- 
 sidered normal at 130 m.m. mercury. 
 
230 Healthful Living 
 
 Modification of pressure and blood flow. We learned that 
 the ability to do this lies in the muscular or middle coat of 
 the vessels, and that the muscular coat in turn is controlled 
 by the nerves. The nerves that control the sizes of the 
 blood vessels are called vasomotor nerves and are of two 
 kinds. One kind, the constrictor nerves, stimulates the 
 walls of the blood vessels to contract, while the other kind 
 of vasomotor nerves, called the dilator nerves, neutralizes 
 or inhibits the effect of the constrictors, and thus allows the 
 blood tubes to enlarge. The regulation is involuntary, or 
 beyond the control of the will; for instance, the blood 
 vessels of the brain may become enlarged and the great 
 pressure there cause a headache, but the will cannot drive 
 it away. We sit before a fire, and the face becomes red as 
 the warmth soothes the constrictor nerves into inactivity; 
 or the constrictors leading to the face may become paralyzed 
 by mental confusion and we blush. 
 
 The amount of blood passing through one organ may be 
 increased by the vasomotor nerves, but it is only because 
 the amount going through the enlarged vessels of that organ 
 has been withdrawn from other organs whose blood tubes, 
 not being enlarged just then, afford greater resistance to the 
 passage of the blood than the dilated vessels afford. But 
 can the total amount of blood reaching, in a given time, 
 not a single organ only, but all the organs in the body, be 
 increased ? Yes, for if the one and one fourth gallon of blood 
 flow faster all over the body, more fresh blood will reach 
 each organ. This is accomplished by faster or stronger 
 beating of the heart. 
 
 During rapid general exercise, as running, when the de- 
 mands of the body are increased, the heart beats faster, as 
 you have doubtless observed. When the body in general 
 is at rest, as during sleep, the heart beats more slowly. Thus 
 the general blood supply is regulated. 
 
 But how is the heart itself regulated? For these facts 
 
The Circulation of the Blood 231 
 
 show two things : first, that we cannot directly control it 
 by the will ; and second, that there is something in the body 
 that does control the heart, and perhaps our wills may in- 
 fluence the beating of the heart indirectly. The heart, like 
 the blood vessels and the muscles in general, is supplied 
 with nerves ; but there is this difference, namely, that the 
 heart can go on beating without receiving impulses along its 
 nerves. The heart of a frog, after being cut out of the body, 
 will go on beating for several hours if it is kept moist ; if it is 
 cut into several pieces, the pieces will go on beating. It is 
 the property of the heart muscle to contract, and it will do 
 so as long as its protoplasm is alive. 
 
 Need for modification. We have learned that there is a 
 mechanism by which the amount of blood in any part 
 may be modified. It is indeed necessary that this be 
 so. The necessity for this comes from the fact that 
 if the one and one fourth gallon of blood were evenly 
 distributed, none of the organs would be capable of 
 any powerful and effective action. A person weighing 
 157 pounds has only 12 pounds of blood, for the blood is 
 Y 1 ^ of the total weight of the body. There is not enough 
 blood in the body to distend all of the blood vessels at once. 
 The skin alone with all of its blood vessels distended could 
 contain two thirds of all the blood in the body. The veins 
 have twice the capacity of the arteries ; they could contain 
 every drop of blood in the body. 
 
 When the brain works, it requires more blood. When 
 digestion is in progress, the lining of the digestive organs 
 blushes a rosy red and the digestive fluids are poured out. 
 During the digestion of a hearty meal, one will not do his 
 best thinking. When a muscle is used, the dilator nerves 
 act, the blood tubes in the muscle become enlarged, and its 
 supply of blood increases to serve it during its action. 
 
 The impulses that run along the vasomotor nerves arise in 
 the enlargement at the top of the spinal cord called the me- 
 
232 Healthful Living 
 
 dulla oblongata . The part of the medulla that in this way regu- 
 lates the caliber of the arteries is called the vasomotor center. 
 It is constantly sending impulses along the constrictor fibers 
 so as to keep the muscles of the arteries slightly contracted. 
 The vasomotor center thus keeps a rein upon the arteries, 
 holding them in a condition of tone, as this slight contraction 
 is called. Sudden paleness, due to fear, is brought about 
 by extra strong impulses from the vasomotor center, caus- 
 ing the muscular walls of the small arteries of the face to 
 grip the vessels tight and driving the blood from the face. 
 Alcohol destroys the tone of the blood tubes. From tem- 
 porary drinking the face becomes red ; from habitual drink- 
 ing swollen blood .tubes in the nose become purple and the 
 " rum blossom " results. 
 
 The heart rate. The rate of contraction of the heart is 
 controlled by nerves. The nerves act not to make the muscle 
 contract but to regulate the frequency of the beats. 
 
 A nerve called the vagus nerve, extending from the medulla 
 oblongata to several organs, goes to the heart ; and gentle 
 impulses which are almost always passing down the vagus 
 nerve from the medulla oblongata, restrain the heart from 
 too great activity, and are the chief means of regulating the 
 strength and frequency of its beats. When an animal re- 
 quires a greater supply of blood, as in running, these im- 
 pulses for a time cease, and the heart beat is quicker and 
 stronger. 
 
 There are other nerves, part of the autonomic nervous 
 system, called accelerator nerves, connected with the spinal 
 cord below the point at which the vagus branches, that 
 bring impulses to the heart which are opposite in effect to 
 those brought by the vagus. These impulses also start 
 in the medulla ; they cause a quickening and strengthening 
 of the beats (Fig. 174). Do the vagus nerve fibers or the ac- 
 celerator nerve fibers resemble the whip which a driver uses 
 in driving a horse? Which kind corresponds to the reins? 
 
The Circulation of the Blood 233 
 
 Thus the need of the body for a greater or less active blood 
 supply is regulated by controlling the rate and strength of 
 the heart beats. If the nerves are all in order, the heart 
 beats more slowly when the tissues of the body need little 
 blood, and more rapidly when the tissues need more food or 
 more oxygen. But quickening of the heart beats cannot 
 send more blood through one organ without sending more 
 blood through all the organs, hence it is not so delicate a 
 means of regulating the blood supply as the vasomotor 
 
 By the nerve mechanism explained in the preceding para- 
 graphs, it is learned that the rate of the heart can be ad- 
 justed. The heart rate is not the same for all people. It 
 varies according to sex, size, and age. The average rate in 
 women is 80 beats a minute, in men 70 beats per minute. 
 Tall individuals have a slower pulse than short ones of the 
 same age and sex. This is true also for animals other than 
 man as shown in the following : 
 
 Elephant ....... 25-28 beats per minute 
 
 Horse . ....... 36-50 beats per minute 
 
 Rabbit ..... ... 140-150 beats per minute 
 
 Mouse ........ 660-670 beats per minute 
 
 The rate is highest in infancy and decreases in adult life. 
 In extreme old age it goes up again. The following indicates 
 the heart rate for different ages : 
 
 At birth ........ 140 beats per minute 
 
 Infancy ... ..... 120 beats per minute 
 
 Childhood . . . . . . . 100 beats per minute 
 
 Youth ......... 85 beats per minute 
 
 Adult ......... 72 beats per minute 
 
 Old age ........ 70 beats per minute 
 
 Extreme age ...... 75-80 beats per minute 
 
 GLOSSARY 
 
 Agglutinin. A chemical product in the blood which arises as a 
 defense to protect the body from disease-producing bacteria. 
 
234 Healthful Living 
 
 The agglutinin has the power of massing the bacteria so that 
 they may be readily ingested by the leucocytes. 
 
 Blood pressure. The pressure which the blood exerts in the blood 
 vessels. It is measured by an instrument called the sphygmo- 
 manometer. 
 
 Corpuscle. One of the cells of the blood. We speak of the red 
 corpuscle and of the white corpuscle. 
 
 Diastole. The period in which the heart is not contracting. It 
 includes the time of relaxation of the heart muscles and the 
 rest before the next contraction. 
 
 Elasticity. The property of tissue by virtue of which the part 
 tends to return to its former size or position. 
 
 Fibrin. A substance formed when the blood clots. In the blood 
 is a protein called fibrinogen. When blood is drawn from a 
 blood vessel, the fibrinogen changes into fibrin. The fibrin 
 is a tough, elastic structure and it holds the blood cells in a 
 firm mass. This is the clot. 
 
 Friction. Resistance to motion due to bodies rubbing in contact 
 with other bodies. 
 
 Hormone. A secretion from glands in which the product of the 
 gland is not passed out through a duct, but passes directly 
 into the blood. Sterling invented the name ; the Greek 
 word opvdw, meaning to stir up, to excite, was used because 
 of the excitatory properties of the secretion. 
 
 Leucocyte. One of the white corpuscles. It is capable of amoe- 
 boid movement and ingests bacteria. A leucocyte has a 
 three-lobed nucleus. 
 
 Lymphocyte. One of the white corpuscles. Lymphocytes are 
 of the large and small variety. They have a single, spherical 
 nucleus. 
 
 Plasma. The liquid portion of the blood. 
 
 Systole. The contraction of the heart. 
 
 Urea. A soluble, colorless, crystalline compound, (CO(NH 2 )2). 
 It is formed in the oxidation of protein in the body and is 
 excreted by the kidneys. 
 
 Uric Acid. A white chemical compound composed of carbon, 
 hydrogen, nitrogen, and oxygen (CeH^N^s). It results from 
 incomplete combustion in the body. At one time it was 
 thought to be the cause of rheumatism, but it is known now 
 that rheumatism is caused by other conditions. 
 
CHAPTER XIII 
 THE CIRCULATION OF THE BLOOD (Continued) 
 
 I. How the Heart Is Aided in Its Work. 
 By valves in the veins 
 By exercise 
 By the lungs 
 By massage and position 
 II. The Lymphatic Circulation. 
 
 How the nourishment gets from the blood into the tissues 
 Lymph 
 
 The origin and course of the lymphatics 
 What makes the lymph flow 
 The lymphatic glands 
 The spleen 
 III. Hygiene of the Circulation. 
 
 The importance of good circulation 
 
 Taking cold 
 
 Effects of unusual exercise 
 
 Sleep and the blood 
 
 The influence of thought and feeling 
 
 Clothing 
 
 Injury to the blood vessels 
 
 The effect of alcohol 
 
 The " tobacco heart " 
 
 Purification of the blood 
 
 How the heart is aided in its work. The heart seems to 
 be constantly at work, but such is not the case. As a 
 matter of fact, the heart occupies nearly as much time in 
 resting as in working. It works for about half a second and 
 rests for about half a second. Yet it does work in a day equiv- 
 alent to raising a ton of coal nearly two hundred feet. This 
 
 235 
 
236 
 
 Healthful Living 
 
 Pec fora/73 
 Major 
 
 work of the heart is aided by the valves in the veins, by mus- 
 cular exercise, by the lungs, and by massage and position. 
 
 By valves in the veins. In- 
 crease the circulation in the arm 
 by exercising it for a few minutes. 
 The veins in the front of the wrist 
 will then be plainly visible (Fig. 
 136). The skin and walls of the 
 veins make the blood in the veins 
 appear blue, but it is dark pur- 
 plish red. (Did you ever see 
 "blue" blood?) Place the tip 
 of the middle finger on one of the 
 large veins ; with the forefinger 
 then stroke the vein toward the 
 heart so as to push the blood from 
 a portion of it, keeping the two 
 fingers in place. The vein re- 
 mains empty between the fingers. 
 Lift the finger nearer the heart, 
 and no blood enters the vein; 
 there is a valve above which holds 
 it back. Lift the other finger, 
 and the vein fills instantly. 
 Stroke a vein toward the hand, 
 and see the blood cause the veins 
 to swell up into little knots where 
 the valves are. (Experiments 
 upon veins are plainest with 
 adults, whose veins are large.) 
 The veins have valves placed 
 frequently along their course. 
 The valves are pockets made by 
 a fold in the inner coat of the wall of the vein (Fig. 137). 
 When you place your hand in your pocket, the latter swells 
 
 FIG. 136. The veins near 
 the surface on the arm. Nerves 
 may be seen accompanying the 
 veins. The fibrous sheaths 
 covering most of the muscles 
 have not been removed. The 
 veins of the first three fingers 
 are not shown. 
 
The Circulation of the Blood 
 
 237 
 
 out ; but if you rub your hand on the outside of the pocket 
 from the bottom toward the top, it flattens down. So with 
 the action of the blood upon the valves ====== 
 
 in the veins (Figs. 138, 139). They all c ^ > H 
 open toward the heart. The valves sup- ~~A 
 
 port a column of blood in each vessel 
 and this support is very valuable in re- 
 turning the venous blood from the legs. 
 
 By exercise. Suppose a muscle hardens FIG. 137. Diagram 
 as it contracts and presses upon a vein of the valves of veins. 
 
 ... A, H, heart side ; 
 
 Which goes through the C, capillary side. 
 
 muscle; the blood is 
 
 The 
 
 arrow shows the direc- 
 tion of flow. B, The 
 pressed OUt Of the Vein. va lve prevents the 
 
 The blood cannot go ^J d from going back " 
 toward the capillaries, 
 for the valves fill and close when it starts 
 that way; so it is all pressed out toward 
 the heart. When the muscle relaxes, the 
 blood that has been pressed forward 
 FIG. 138. Valve cannot come back because of the valves, 
 but the valves nearer the 
 capillaries open, and the 
 When the muscle contracts 
 
 again, the same effect on the blood move- 
 
 ment is repeated. We see, therefore, that 
 
 every contracting muscle acts like a pump 
 
 forcing the blood through the veins, and 
 
 when a person works or exercises, many 
 
 pumps of a muscular kind are working all 
 
 over the body, aiding the heart in its func- 
 
 tion (Fig. 140). This aid makes the blood 
 
 flow faster and relieves the heart of part of 
 
 its work, so that it beats faster, just as a 
 
 horse might trot faster if half the load were removed. All 
 
 of the body gets fresher blood than it got when the muscles 
 
 veins are filled. 
 
 FlG - i39.-Vein 
 
Healthful Living 
 
 were still and the blood flowed more slowly. This help 
 
 comes during active work, just when the body is demanding 
 
 more blood and the heart needs help. 
 
 By the lungs. On inspiration * the lungs help to circulate 
 
 the blood, since, when they expand and the air rushes into 
 
 them, the blood as 
 well is drawn to- 
 ward the cavity of 
 the chest. 
 
 Does the elas- 
 ticity of the arterial 
 wall furnish any 
 force to aid the 
 heart? No. When 
 the arteries con- 
 tract as the pulse 
 passes, it is the 
 force of the heart 
 that is doing it. 
 When you open a 
 door or gate that is 
 closed by an elastic 
 spring, it is the 
 force furnished by 
 you to the spring 
 that shuts the door 
 
 FIG. 140. -Diagram showing effect of mus- after y U release 
 
 cular contraction upon venous circulation. The your hold, 
 
 valves prevent the blood from flowing in two * R <mn**nnP n<nrl 
 directions ; it can only flow toward the heart. D 9 ' Sa Q e 
 
 position. So effec- 
 tive and necessary is exercise in aiding the circulation, that 
 some people employ others who are skilled in the art called 
 massage, to come regularly and squeeze and knead every 
 muscle like dough. Thus fresh blood is brought and the 
 removal of waste material from the tissues is aided. This 
 
 ~*\~Contractect 
 
 VatveofVein 
 
The Circulation of the Blood 239 
 
 will remove waste material, but such a person misses the tonic 
 effect on the nervous system that comes from participating 
 in sports and activities with other people. The artificial 
 makeshifts of man never include all that Nature would give. 
 
 The arteries lie deep under the muscles near the bones, 
 and are likewise pressed upon by muscles, but their walls 
 are much stiffer than the walls of the veins. In fact, many 
 of them in passing through the muscles have tough, fibrous 
 sheaths. It is well that the arteries are not so much af- 
 fected by exercise, for if they were squeezed by the con- 
 tracting muscles, the blood would be pressed backward as 
 well as forward since they are destitute of valves, and this 
 would not be favorable to the circulation. 
 
 So called " growing pains " in a child are due often to 
 exposure to cold and wet or to falling arches in the feet. 
 These pains may come from overfatigue or may be a slight 
 form of rheumatism. The feet should be examined and if 
 at fault the proper treatment should be given. Massage of 
 the muscles and parts after overwork is beneficial and useful. 
 
 Position of the body may aid the flow of blood by over- 
 coming the action of gravity in the large vessels of the legs. 
 The circulation will be assisted by assuming a lying position. 
 After a long walk, or tiring exercise, the circulation will be 
 aided by elevating the feet and legs. 
 
 The lymphatic circulation. The lymphatic * system com- 
 prises lymphatic vessels distributed over the entire body, 
 glands located in large numbers throughout the body, es- 
 pecially in the groin and in the armpit, and the spleen, whose 
 exact function is unknown but whose structure is lymphatic 
 in character. 
 
 How the nourishment gets from the blood into the tissues. 
 We left the food and oxygen in the capillaries. How does 
 it get out of them into the tissues? We found that the 
 blood flows very slowly in the capillaries (-$ of an inch per 
 second), and that the capillary walls are very thin, being made 
 
240 
 
 Healthful Living 
 
 of only the inner of the three coats that make the veins and 
 arteries. Here, then, are two favorable conditions for giv- 
 ing up the nutrition (Fig. 141). We learned that the protein, 
 carbohydrates, and fats were dissolved in the plasma, or 
 liquid portion of the blood. The plasma passes through the 
 thin capillary walls, carrying the food with it. When it gets 
 outside the capillaries, it is next to the walls of the cells that 
 make up the tissues. These spaces are called lymph spaces. 
 
 Thus the lymph * bathes 
 the cells in the nutritious 
 fluid, and the hungry 
 cells absorb what they 
 need. The oxygen is 
 carried in chemical com- 
 bination with the haemo- 
 globin of the red cor- 
 puscle. 
 
 The red corpuscles 
 bearing the oxygen can- 
 not get through the cap- 
 illary walls. But the 
 oxygen is carried also in 
 the plasma and it easily passes out into the tissues. The cells 
 in the tissues use up the oxygen of the plasma and the plasma 
 replenishes its supply from the red blood corpuscles. Carbon 
 dioxide, which is one of the products of the combination of 
 oxygen with the food material in the tissues, is also a gas. 
 It returns to the heart and to the lungs in the plasma of the 
 venous blood and the lymph. 
 
 Why cannot the capillaries themselves carry the food and 
 oxygen into the tissues? Because they are tubes, and as 
 long as the food is in the blood it cannot reach the -cells; 
 the capillary walls prevent. The lymph spaces and the 
 lymphatics act as middlemen between the blood and the 
 cells (Fig. 142). 
 
 Vein 
 Artery 
 
 FIG. 141. Capillaries connecting a 
 small artery with a small vein. 
 
The Circulation of the Blood 
 
 241 
 
 Lymph. If the plasma kept coming into the tissues 
 without any way of getting back into the blood vessels, the 
 blood would soon be . 
 
 lacking in plasma and 
 
 the tissues would be op- 7*** Ce//s j ^ 
 
 pressed with it. We Lymphat/c . ^ 
 see, then, the absolute 
 necessity for some pro- 
 vision to get this liquid 
 back into the blood 
 vessels, from which it is 
 constantly overflowing. 
 This is done by a system 
 (Fig. 143). 
 
 What is lymph? 
 
 FIG. 142. Diagram to show function of 
 lymph and origin of lymphatics. 
 
 of tubes called lymphatics 
 
 lymphatic 
 
 of the right arm. 
 
 B 
 
 The blood plasma is called lymph after 
 it gets out of the capillaries. But it 
 soon becomes changed by the addi- 
 tion of substances thrown out by the 
 cells, and by giving up to the cells the 
 digested food brought by the blood. 
 We should have said also that the 
 white blood corpuscles may pass out 
 into the lymph, especially if there is 
 some condition in the tissues that 
 they can correct (Fig. 124). 
 
 We may say, then, that lymph is 
 nearly the same as the blood without 
 the red corpuscles. Did you ever see 
 any lymph? Certainly you have seen 
 it, many times. Whenever there is a 
 blister in the skin from friction, or 
 from a burn, the lymph collects. 
 Sometimes when the skin is grazed, 
 but blood vessel touched, the 
 lymph may exude. 
 
242 
 
 Healthful Living 
 
 The origin and course of the lymphatics. Unlike the 
 blood vessels, the lymphatics, or the tubes which carry the 
 
 Super/or 
 Vena Cava 
 
 Thoracic Duct 
 
 Keceptocu/um 
 Chy/i 
 
 Left Jugu/ar 
 "Vein 
 
 .Left -Subc/av/an 
 Vein 
 
 Lymphatic 
 
 in Lumbar J?e(fions\ 
 
 FIG. 144. The thoracic duct. Note the opening of thoracic duct into 
 the junction of left jugular and left subclavian veins. The connection 
 of these veins with the superior vena cava has been cut across to show the 
 thoracic duct behind it. The lymphatic glands in the lumbar region mark 
 the beginning of the thoracic duct. 
 
 lymph, have a beginning. The blood vessels do not begin, 
 but make a never-ending circle. The lymphatics begin 
 in open ends between the capillaries and the cells, or among 
 
The Circulation of the Blood ' 243 
 
 the cells themselves (Fig. 142). It will be interesting to 
 learn how they lead the lymph back to the circulation, and 
 what makes it flow, for surely there is no heart for the lymph 
 as there is for blood. When the lymph once enters the open 
 end of the lymphatic, it does not return to the blood, but 
 continues to move slowly or at intervals through the lym- 
 phatics on its return to the blood system (Fig. 144). Small 
 lymphatics come together and form larger ones. They 
 continue to unite and form larger ones, until finally the 
 lymphatics from nearly the entire body unite into one large 
 tube, which passes up through the abdomen and thorax, 
 and pours the lymph into the venous system beneath the 
 collar bone near the neck. This largest of all lymphatics 
 is called the thoracic duct. 
 
 The thoracic duct is about the size of a goose quill, and 
 empties into the venous system just where the large vein 
 from the left side of the head (the left jugular vein) joins 
 the large vein from the left arm (left subclavian vein) 
 (Fig. 144). We said the lymphatics from nearly all over 
 the body form the thoracic duct; but the lymphatics from 
 the right arm and right side of the trunk and head form 
 what is called the right lymphatic duct, which empties into 
 the right subclavian vein just where the right jugular vein 
 joins the latter. (See Plates.) 
 
 What makes the lymph flow. Did we not learn that some- 
 thing besides the heart makes the blood flow? It is the 
 contraction of the muscles and their consequent pressure 
 upon the veins. The valves in the veins make this pressure 
 effective by allowing the blood to be forced in only one 
 direction. It is likewise found that the lymphatics have 
 valves, and that they are more abundant than those of the 
 veins. Whenever the muscles contract, the lymph is forced 
 along, and the valves provide that no progress made shall 
 be lost by any backward movement. Every pressure leaves 
 a part of the lymphatic empty and ready to fill from behind 
 
244 
 
 Healthful Living 
 
 (Fig. 145). Also, if the body is pressed upon or shaken, as 
 
 when riding a trotting horse, or in a jolting vehicle, the lymph 
 is moved beyond the valves at every jolt, and 
 its circulation aided. 
 
 The secret of the powerful effect of mus- 
 cular work upon the health lies chiefly in the 
 great aid that it gives the lymphatic and 
 venous circulations. The importance of an 
 active lymphatic circulation is seen when we 
 remember that the blood does not make its 
 exchange directly with the cells of the tissues, 
 but with the lymph, and the lymph makes 
 the exchanges with the tissue cells. 
 
 The lymphatic glands. Along the course 
 of the lymphatics, nu- 
 merous enlargements oc- 
 cur called lymph nodes * 
 or lymph glands (Fig. 
 146) . They consist of a 
 connective tissue frame- 
 work, the meshes of 
 which are crowded with 
 lymph cells. The lymph 
 in its course must filter 
 through these clusters of 
 
 cells, and, in doing so, is purified ; for 
 
 the node cells take up impurities in 
 
 the lymph, and work over and change 
 
 their nature. The cells in these nodes 
 
 FIG. 146. Lymphatic 
 
 multiply, and some of them are taken gland. Showing vaived 
 
 up by the lymph and carried into the 
 
 blood to become those remarkable 
 
 little bodies, the white blood corpuscles. It is a curious 
 
 fact that the older white corpuscles are broken up in the 
 
 lymph nodes, and their Vemains are absorbed by the newly 
 
 FIG. 145. A 
 full lymphatic 
 with its valves 
 distended (cut 
 open) . 
 
 ******* 
 
The Circulation of the Blood 245 
 
 formed white corpuscles, just as the latter absorb germs 
 and other foreign particles that may enter the blood. The 
 lymphatics penetrate and help in the nourishment of every 
 tissue, even in that of the bony tissue. 
 
 The spleen. This organ resembles the lymph nodes. It 
 is purplish red, about five inches in length, and is situated 
 just inside of the lower ribs on the left side of the abdomen. 
 White corpuscles are formed in it as well as in the smaller 
 lymph nodes. In it also the red corpuscles that have finished 
 their service in the blood are probably broken up and de- 
 stroyed. 
 
 Hygiene of the circulation. Have you learned yet the 
 curious fact that all of the living cells of the body live under 
 water, just as the amceba does? The lymph and the blood 
 are chiefly water and the cells are all bathed continually in 
 one or the other. The blood bathes the cells in the walls 
 of its vessels, and the lymph, or the blood without the red 
 corpuscles, is found filling the interstices or spaces between 
 the cells, like water in a sponge. From the spaces, as we 
 learned, it is taken by the lymphatics in order to make room 
 for fresh lymph, free from waste material and bringing fresh 
 nourishment. The only exception to the rule that the cells 
 live a watery existence, is found on the surface of the body ; 
 the cells of the outer skin, hair, and nails, however, may be 
 called dying cells, for they are not. alive in the same sense 
 that the other cells are : they do not contain nuclei and can- 
 not repair themselves or grow. 
 
 The importance of good circulation. The supreme, the 
 transcendent importance to the health of the tissues, of pure 
 blood and good circulation, now becomes apparent. All 
 that the cells need, in order to be sound and vigorous, is to 
 have good food and oxygen brought within their reach, and 
 to have the waste material, or products of combustion, re- 
 moved ; the circulation meets, these needs. 
 
 When unsoundness occurs in any part of the body, there 
 
246 Healthful Living 
 
 is a strong probability that the circulation there is defective. 
 The hair is lost by cutting off the circulation from the scalp. 
 The eyes may become inflamed, or the lids diseased, because 
 of obstructing in the neck the return of the blood from the 
 head ; improper neck clothing or stiffened muscles may 
 cause this obstruction. Indigestion may result if vigorous 
 mental or physical activity, just after eating, draws the 
 blood away and prevents the secretion of the digestive fluids. 
 Gout may occur from the deposit of waste materials in the 
 spaces around the joints where the pressure from the circu- 
 lation is least. Colds occur when the blood vessels in the 
 walls of the air passages become congested or swollen with 
 blood, and the vessels lose their tone so that they cannot 
 contract and keep the blood moving onward. 
 
 Pure blood is just as necessary as free and unimpeded 
 circulation. We shall learn later how the digestive organs 
 serve to furnish the nutrition, how the lungs furnish the 
 oxygen, and how the skin, kidneys, and lungs remove from 
 the blood the impurities and waste materials. 
 
 Taking cold. Sudden or prolonged exposure to cold 
 while the muscles are inactive, so stimulates the surface 
 blood vessels through the vasomotor nerves that they be- 
 come tightly contracted and send the blood to the interior 
 of the body. It accumulates there and may cause such con- 
 gestion of the mucous membrane of the nose, throat, wind- 
 pipe, or lungs, that inflammation ensues. A cold is an in- 
 flammation of the mucous membrane of part of the air 
 passages. Rapid cooling off from a heated condition, es- 
 pecially if one is in a profuse perspiration, may cause the 
 same results ; or, exposure to moderate but continuous cold 
 without exercising may bring on a cold. Sitting on the 
 damp ground, sitting with damp feet, sitting for a long time 
 in a cool draught, or going thinly clad in cool weather, may 
 cause a cold ; only foolish persons think they are so hardened 
 as to withstand such risks without injury. 
 
The Circulation of the Blood 247 
 
 A person may be in the habit of coddling himself by living 
 in overheated rooms, or by wearing too warm clothing and 
 by constant use of mufflers on going out ; his surface nerves 
 thus become so delicate and the blood vessels of the surface 
 so relaxed, as to insure taking cold on every accidental or 
 unavoidable exposure. A better plan is to keep the house 
 cool, the thermometer standing at 65 to 68, sleep with open 
 windows, take cool baths, and keep warm when out of doors 
 by walking or exercising briskly. Thus the blood vessels 
 are toned up, the circulation is made vigorous and steady, 
 and the person is better fitted to withstand the ordinary 
 conditions of life without disease continually recurring owing 
 to deranged or weak circulation. Any process of " harden- 
 ing to cold " that is not accompanied by vigorous exercise 
 is a risk to the health. 
 
 The reciprocal action of the blood vessels of the skin and 
 the internal organs is sometimes illustrated when a person 
 drinks freely of cold water. There is a sudden breaking out of 
 perspiration. Why is this? Certainly the water does not 
 reach the skin so quickly. The cold in the interior stimu- 
 lates the internal vessels to contraction and the blood is 
 diverted to the unstimulated vessels of the skin, surrounding 
 the sweat glands. 
 
 Effects of unusual exercise. If a person has sedentary 
 habits and has neglected active exercise for some time, the 
 heart, as well as the other muscles, becomes weak. If such 
 a person hurries to catch a train, or takes very rapid and 
 trying exercise of any kind, he may bring on an unpleasant 
 palpitation of the heart, which is a warning to desist at 
 once. Violent exercise should not be taken until one has 
 gradually led up to it. 
 
 Sleep and the blood. A person who loses much sleep be- 
 comes pale ; the paleness is evidence of a diminution in the 
 number of red corpuscles. It is during sleep that the cor- 
 puscles that have been worn out during the day are replaced, 
 
248 Healthful Living 
 
 but loss of sleep causes a greater loss to the blood than usual, 
 with less than the usual opportunity for repair. 
 
 The influence of thought and feeling. Rage excites and 
 strains the heart. The experience of great emotion, either 
 of joy or anger or fright, often raises the blood pressure so 
 much that a vessel is broken and death occurs. Calmness 
 and poise* are mental qualities that have desirable effects 
 upon the circulation. 
 
 Clothing. The blood cannot circulate with perfect 
 freedom unless the entire body is so loosely clothed that there 
 is no pressure upon any of the blood vessels, no interference 
 with the lungs as they expand, no pressure upon the stomach, 
 liver, and intestines. Many of the largest veins, particu- 
 larly those of the arms and legs, lie so near the surface that 
 any tightness of the clothing is certain to diminish the flow 
 of blood through them. Sleeve supporters and garters, if 
 used at all, should be of weak elastic with adjustable buckle, 
 and no tighter than is absolutely necessary. It is especially 
 necessary to keep the extremities warmly clad and dry. 
 
 Injury to the blood vessels. To perform effectively the 
 work of transporting the blood, the vessels must remain 
 whole, and they must keep their shape and elasticity. In- 
 jury of the vessels may occur by cutting of the vessel wall 
 or by changes in the wall so that it loses its shape or 
 elasticity. 
 
 Hemorrhages. Hemorrhage is a flow of blood from an 
 injured blood vessel. When the wound is slight, the clotting 
 of the blood stops the flow. Clotting is rapid in the blood of 
 healthy persons and slow in the blood of poorly nourished 
 persons. Blood does not spurt from a cut vein but flows in 
 a slow stream. When an artery is cut, the blood comes forth 
 in a jet, with stronger spurts at each throb of the heart. 
 In a large artery the pressure is so strong that it forces away 
 the clot as fast as it is formed, so that death may result 
 from loss of blood. 
 
The Circulation of the Blood 249 
 
 Varicose Veins. Varicose veins are enlarged and tor- 
 tuous veins. This condition occurs more frequently in 
 people who take little exercise, who follow occupations in 
 which they stand still for long periods, as motormen and 
 clerks. Postmen who are on their feet a great deal but very 
 active rarely suffer from varicosi ties.* Why is this so? Has 
 muscular contraction anything to do with the circulation of 
 the blood (Fig. 140) ? Tight garters should not be worn, 
 because they prevent the venous flow by constricting the 
 part. 
 
 Hardening of the Arteries. Hardening of the arteries 
 occurs in late adult life and seems to be caused by intemperate 
 living. Too much physical work, too much mental work, 
 too much work for the digestive organs, may produce a 
 hardening of the arteries. The loss of elasticity is caused 
 by an accumulation of salts in the wall of the artery. The 
 salts make the artery hard. It becomes, therefore, less able 
 to adjust to changes in pressure, and it will break more 
 easily. 
 
 The effect of alcohol. It is believed that the white cor- 
 puscles are injured by alcohol in the blood, and that they 
 lose to some extent their activity in attacking poisons and 
 germs of disease. This gives an explanation of the sus- 
 ceptibility* of drinking men to germ diseases. Persons ac- 
 customed to use alcohol are usually the first victims of 
 cholera and of yellow fever; while some abstainers, under 
 constant exposure, remain untouchecl. The white corpuscles 
 repair cuts and broken bones ; hence intemperate persons 
 do not recover from accidents and surgical operations as 
 quickly as do total abstainers. 
 
 The " tobacco heart." - Tobacco, unlike alcohol, does not 
 dilate the blood vessels of the skin ; tobacco users are often 
 pale from want of blood in the skin. We thus see why 
 tobacco users develop a stronger craving for drink than non- 
 users, because the alcohol has, in some respects, an effect 
 
250 Healthful Living 
 
 opposite to that of tobacco. However, heart action is 
 temporarily increased when tobacco is used. In the previous 
 chapter you learned that the accelerator * nerves increase the 
 heart action and the vagus nerves (inhibitory *) hold it in 
 check. The vagus is partially paralyzed by tobacco, and the 
 heart beats with more force, thus exhausting itself. The 
 pulse of the habitual user shows unmistakably the injury 
 done to the heart. It loses the firm steady beat of health 
 and becomes irregular. Most of the time its beat is feeble ; 
 for a period its beat may be rapid and palpitating. This 
 condition is known to physicians as the " tobacco heart." 
 
 Physicians who have made a special study of the subject, 
 claim that one out of every four tobacco users has the tobacco 
 heart. It prevents success in athletic contests and feats 
 of strength. It prevents a large proportion of the young 
 men who apply for enlistment, from entering the army. 
 Knowing the paramount importance to sound health of 
 rich blood and perfect circulation, we are not surprised to 
 know that the whole body is enfeebled by tobacco, and that 
 mental as well as physical vigor is impaired. Observant 
 teachers can often tell which of the boys in school are ad- 
 dicted to the use of tobacco from the comparative inferiority 
 of their appearance and from their indolence of body and 
 mind. 
 
 Purification of the blood. The impurities of the blood 
 are the waste substances which result from the chemical 
 action occurring in the body cells. This waste material is 
 removed from the body if the circulation is adequate and if 
 exercise is sufficient. The blood is freed from these im- 
 purities by the lungs, by the sweat glands of the skin, and by 
 the kidneys. This process of blood purification is natural, 
 and will at all times suffice, if the individual drinks enough 
 water, avoids constipation, and exercises sufficiently. There- 
 fore, patent medicines which claim to " purify the blood " 
 are never necessary, if one follows the natural laws of health. 
 
The Circulation of the Blood 251 
 
 Furthermore, the claim of purification is false and they never 
 accomplish their purpose. Patent medicines are made to 
 sell and not to accomplish any particular result in the body. 
 
 Activity is the most necessary condition for the health 
 of a cell. In every cell is found matter in three conditions : 
 that which is actually living, that which was recently living, 
 and that which is about to live by being transformed in the 
 cell. The transformation from lifeless to living, and from 
 living to dead, and the removal of dead matter must go on 
 promptly. Anything which interferes with this activity 
 interferes with the health of the cells. When life is natural 
 and complete, all the organs are given work to do and are 
 healthy, active, and strong; there is a feeling of buoyant 
 happiness, the mind is clear, the will is firm, and the man 
 truly lives. Therefore, pure blood will be available for the 
 ceaseless activity of the cells if proper and sufficient exercise 
 is taken. 
 
 APPLIED PHYSIOLOGY 
 Exercise I 
 
 1. The main arteries run down the middle of each limb close to 
 the bone on the side toward which the limb bends. Why do they 
 have this position ? 
 
 2. Where is the thickest wall of the heart? Why? The 
 thinnest walls? Why? 
 
 3. Why do we need warmer covering when asleep than awake ? 
 
 4. When would it be pleasant to throw off a coat or cloak, 
 but imprudent to do so ? 
 
 5. If the clothing has been accidentally wet and the wet gar- 
 ments cannot be changed for dry ones at once, how can one keep 
 up a good circulation to prevent taking cold ? 
 
 6. When cold air strikes it, why does the face first blanch and 
 then flush? 
 
 7. When a person is warm-hearted in the usual sense of the 
 term, is it also true physiologically? 
 
 8. When do dark veins in the wrist show most plainly? 'Of 
 what is dark blood in the body in general a sign? 
 
252 Healthful Living 
 
 9. Why does a hot foot-bath sometimes relieve a headache? 
 Why should it relieve a cold in the head ? 
 
 10. How is the blood purified ? 
 
 Exercise II 
 
 11. Tight clothing at the waist may cause too much blood in 
 what parts? Does it tend to make the circulation sluggish or 
 active ? 
 
 12. Which is more compressible, a vein or an artery? Does a 
 tight garter interfere more with the flow of blood to the feet or 
 from the feet ? 
 
 13. Why are varicose veins so often found in the lower leg? 
 
 14. Why may a sluggish circulation through full veins in the 
 feet as well as want of blood in the feet cause them to be cold? 
 
 15. Why are students very likely to have cold feet ? 
 
 16. Why does the body of a person dying by drowning or 
 strangulation turn blue ? 
 
 17. What would you do in the case of a severe wound in the 
 absence of a surgeon? 
 
 18. What is the object of a collar? Why is it, therefore, not 
 necessary to have the collar as high in front as behind? Why 
 is it unhealthful to have it so? What is the purpose of a cuff? 
 
 19. What is the most serious injury of alcohol to the blood? 
 
 20. In what part of the circulation does the so-called venous 
 blood flow through arteries? 
 
 Exercise III 
 
 21. Show how life comes by death. 
 
 22. Can any physiological basis be given for the claims of 
 patent medicine venders that their nostrums "purify the blood "? 
 
 23. What vein begins and ends with capillaries? 
 
 24. What artery takes arterial blood to an organ where it is 
 still further purified, yet is called venous blood when it leaves 
 the organ? (As it leaves that organ the blood is the purest in the 
 body. See Plate VIII.) 
 
 25. What keeps the blood in circulation between the beats of 
 the heart? 
 
 26. What are the functions of the capillaries ? 
 
 27. Why is a cool draft in the house more apt to cause a cold 
 than a cool wind out of doors ? 
 
The Circulation of the Blood 
 
 253 
 
 28. Why do we perspire freely after drinking freely of cold 
 water ? 
 
 29. What causes the difference between the hard hand of the 
 blacksmith and the soft hand of the clerk? 
 
 30. Why does rubbing wear out the leather of the shoe, but 
 the friction of the shoe upon the toe cause the skin to grow thicker 
 and to form a corn ? 
 
 31. What is the effect upon the circulation of horseback riding? 
 
 LABORATORY EXERCISES 
 
 Experiment 1. To demonstrate circulation, vasomotor control and 
 
 blood pressure. 
 
 Arrange an inverted bell jar (Fig. 147) on a support and connect 
 it with a series of glass pipes arranged in an upright position. For 
 
 _G/BSS_ 
 
 Tubing 
 
 ~^~- Wafer 
 
 "Hart* Rubber- Tubing' 
 
 FIG. 147. 
 
 the connections use a hard rubber tubing. Before the last two 
 pipes insert a section of soft rubber tubing and attach a clamp which 
 will allow graduated pressure to be made on this section of the 
 circulation. Fill the bell jar with water colored with carmine and 
 notice the following : 
 
 1. Name the heart, the arteries, the capillaries, and the veins. 
 
 2. Have the clamp entirely free and observe the effect upon the 
 flow of water. How high does the liquid rise in the tubes ? Mark 
 the point in each case. 
 
 3. Close the clamp down so that no liquid flows from the venous 
 end. How high does the liquid rise in the tubes ? In which tube 
 
254 Healthful Living 
 
 is it highest? Is this the tube that corresponds with the arteries 
 nearest the heart ? 
 
 4. Open the clamp enough to have the liquid flow from the 
 venous end in a slow and constant stream. Notice the change in 
 the height of the liquid in the tubes. What are the points of 
 difference between the effect seen in (1) and (2)? Would you say 
 that the pressure decreased from the heart to the capillaries and 
 that in the venous system the pressure was very low until in the last 
 tube it was practically at zero ? 
 
 When the capillaries are shut down, what effect has that on the 
 blood pressure? Is the resistance to the flow of blood increased? 
 How is such effect produced in the .body? 
 Experiment 2. To study the heart rate in exercise. 
 
 Material. Watch with a second hand. 
 
 Method and observation. (a) Palpate the pulse in the radial 
 and temporal arteries, feel with the tips of the first and second 
 fingers. What causes the pulsation? (6) Count the radial pulse 
 during consecutive 15 second periods (one quarter minute) and 
 when the rate in any two successive ones are alike, take that rate 
 as the rate of the heart for the time and activity. Find the heart 
 rate per minute in the following : 
 
 1. Horizontal position, face up. 
 
 2. Horizontal position, face down. 
 
 3. Sitting position. 
 
 4. Standing position. 
 
 5. After 10 deep knee bendings. 
 Does the rate vary? Why? 
 
 Experiment 3. To study the heart rate in respiration.* 
 
 Material. Watch with a second hand. 
 
 Method and observation. Count the radial pulse and obtain 
 the rate as described in experiment (1). With that procedure 
 obtain the heart rate during the inspiratory phase and the expira- 
 tory phase. Is the rate different ? In which is it faster? 
 Experiment 4. To study the heart rate in exercise and respiration. 
 
 Material. Watch with a second hand. 
 
 Method and observation. Count the heart rate in the standing 
 position. Perform twenty deep knee bendings and count the 
 heart rate at once at the end of the exercise. Notice the difference 
 during the inspiratory and expiratory phases of the respiration. 
 
The Circulation of the Blood 255 
 
 GLOSSARY 
 
 Accelerator. A mechanism that increases the speed of an organ. 
 
 Applies to the nerves which go to the heart and increase the 
 
 rate of contraction of that organ. There is an accelerator 
 
 center. 
 Expiration. The act of breathing out. It comes from the Latin, 
 
 ex meaning out, and spiro, to breathe. 
 Inhibitory. A mechanism that checks the activity of an organ. 
 
 The effect is opposite to that produced by the accelerator nerves 
 
 or center. The inhibitory nerves of the heart are the vagi. 
 Inspiration. The act of breathing in. Its derivation is similar 
 
 to the derivation of expiration. 
 Lymph. The fluid that bathes the cells and lies in the spaces 
 
 between the cells. It is carried to the heart by the lymphatics. 
 
 It is derived from the plasma of the blood. 
 Lymphatic. A tube composed of thin cells and serving to carry 
 
 the lymph from the cell and tissue spaces back to the heart. 
 Lymph nodes. Small glandular structures situated along the 
 
 course of the lymphatics and especially numerous at the joints. 
 
 They serve to take out of the lymph, poisons that would injure 
 
 the body. 
 
 Poise. Balance, equilibrium. 
 
 Respiration. The act of taking in and breathing out air. 
 Susceptibility. The condition of yielding or succumbing readily. 
 
 Resistance is the opposite quality. One who has little resist- 
 ance shows susceptibility. 
 Varicosity. A condition in which the veins are dilated, twisted, 
 
 and tortuous. 
 
CHAPTER XIV 
 THE RESPIRATION 
 
 I. Why Breathing Organs are Needed. 
 II. The Respiratory Organs. 
 
 The nose, throat, larynx, and trachea 
 
 Bronchial tubes 
 
 Lungs 
 
 The diaphragm and other muscles 
 III. The Breathing Process. 
 
 Inspiration 
 
 Expiration 
 
 Ease in breathing 
 IV. The Air We Breathe. 
 
 Composition of the air 
 
 Foul and fresh air 
 V. The Hygiene of Respiration. 
 
 Breathing through the nose 
 
 Muscular action in breathing 
 
 Respiratory exercises 
 
 Ventilation 
 
 The effect of tobacco on the respiratory organs 
 
 General considerations 
 
 Why breathing organs are needed. Every cell in the 
 body requires oxygen to enable it to do its appointed work. 
 When the supply of oxygen stops, the activity of the cell 
 ceases at once. If it is a muscle cell, motion can be generated 
 in the muscle only by the union of oxygen with the contents 
 of the cell. If it is a gland cell, it cannot do its work of se- 
 creting useful fluids without the help of oxygen, for the sub- 
 stances which the gland cell takes from the blood must be 
 
 256 
 
The Respiration 257 
 
 changed to form the secretion. If the cell is a brain cell, 
 although it may not use as much as a muscle cell uses, oxygen 
 is still indispensable. The oxidation that takes place in the 
 various cells results in the formation of carbon dioxide and 
 other waste products which would destroy the life of the cell 
 if allowed to remain; these are removed from the body by 
 the same organs that supply the oxygen. How does the 
 amoeba get its oxygen ? 
 
 The respiratory organs. It is obvious that in animals of 
 large size with many tissues, the great majority of the living 
 cells of the tissues must be buried deep away from the ex- 
 ternal surface. But even if 
 deep-seated and away from 
 the air, the living cells have 
 the same need of oxygen as 
 
 , , ff Lobvte l^fXKiry ;=?- Lobule 
 
 though near the surface. If 
 
 oxygen is supplied to the 
 blood, the latter conveys the 
 oxygen to the cells ; but it 
 is seen that a very efficient 
 organ is needed to supply 
 the blood with oxygen suffi- FIQ U8 _ Two , obules at the 
 
 cient for SO many cells. The end of a bronchial tube. 
 
 breathing apparatus varies 
 
 in different animals ; (1) it usually consists of a device for 
 exposing to the air a great amount of thin tissue, which 
 is a specialized form of the outer skin of the animal (if the 
 animal is not a land animal, the tissue is exposed to the water) ; 
 (2) the animal is further provided with means to keep up a 
 current of air (or water) on the outside of this modified skin 
 and a current of blood on the inside. Large animals with 
 many deep-seated and inaccessible cells require for suf- 
 ficient oxygen a large respiratory area. This is provided by 
 having it folded as indicated in Figure 148. In man, it has 
 been estimated that by the finer and finer division of the air 
 
258 
 
 Healthful Living 
 
 sac, a pair of human lungs presents to the air a surface of at 
 
 least one hundred square feet (or ten feet square) ; (3) the 
 
 remainder of the breathing apparatus consists of muscles 
 
 for changing that air that is in contact with this great surface. 
 
 Nose, throat, larynx, and trachea. The air usually passes 
 
 in at the nose and returns by the same way, except during 
 
 /A/Ml talking or singing. 
 
 ThyroM Cartilage VlSf \-Larynx If ? lo k ln y UI * 
 
 fc J ' mouth with a mirror, 
 
 you will see at the 
 back part an arch 
 which is the rear 
 boundary line of the 
 mouth. Just above 
 the arch is likewise 
 the limit for the back 
 part of the nasal 
 passages. The fun- 
 nel-shaped cavity 
 beyond, into which 
 both the mouth and 
 nasal passages open, 
 is called the pharynx 
 
 FIG. 149. Not all of the divisions of the r ' 
 
 bronchi are shown, but notice how these tubes (far inks), Or throat, 
 
 by the finest branches extend to all parts of the Below two tubes 
 
 Jungs. ' 
 
 open from the phar- 
 ynx, one into the trachea (trak'e-a) or windpipe, the other 
 into the esophagus, or gullet. At the top of the trachea 
 (Fig. 149) is the cartilaginous larynx, or voice box, and the 
 opening from the throat is provided with a lid, the epi- 
 glottis, also consisting of cartilage. The larynx will be 
 described more fully in treating of the voice ; it may be 
 felt as the Adam's apple. Just below it comes the trachea 
 proper which is a tube about three fourths of an inch in 
 diameter, and about four inches long (Fig. 149). It con- 
 
The Respiration 259 
 
 sists of hoops of cartilage which are not complete circles 
 but are shaped somewhat like the letter C, being com- 
 pleted behind by nonstriated (involuntary) muscular tissue, 
 whose function is to draw the ends of the rings together at 
 times, e.g. during coughing, and reduce the caliber of the 
 tube. The function of the hoops of cartilage is to keep 
 the windpipe open at all times. If it should collapse under 
 pressure, life might be lost. These rings of cartilage may 
 be felt in the neck. 
 
 Bronchial tubes. The lower end of the trachea is just 
 behind the upper end of the sternum; and there -it divides 
 into two bronchi, called the right bronchus and the left 
 bronchus (plural, bronchi). The bronchi subdivide into a 
 great number of smaller branches, called bronchial tubes. 
 Cartilage is found in the walls of all but the smallest of the 
 tubes. The subdivision continues until the whole lung is 
 penetrated by branches, all having the general name of 
 bronchial tubes (Fig. 149). The smallest are only about ^ 
 of an inch in diameter. They ramify through the lungs, 
 somewhat like the branching of a tree, each tiny tube finally 
 ending in a wider funnel-shaped chamber called a lobule 
 (Fig. 148), into which so many dilated sacs, called air cells, 
 open that the walls of the terminal chamber, or lobule, may 
 be said to consist of tiny cups, or air cells, placed side by 
 side. (The word " cell " is here used in its original sense to 
 denote a cavity or chamber, and not in the sense of a proto- 
 plasmic cell.) 
 
 Lungs. The lungs are elastic air-containing organs 
 constructed of epithelial cells of several kinds and blood 
 vessels. The air cells are arranged to allow air to come 
 readily into contact with the blood, and to remove from the 
 lining the dust and dirt that has come in with the air. The 
 numerous blood vessels afford means of rapidly moving the 
 blood through the lungs. The elastic nature of the lungs 
 provides for easy and quick inflation. These characteristics 
 
26o 
 
 Healthful Living 
 
 FIG. 150. -?-The wall of an 
 air cell, a, the epithelium ; 
 b, partition between two air 
 cells, in which the capillaries 
 lie ; c, fibers of elastic tissue. 
 Notice b, and name the struc- 
 tures through which oxygen 
 and carbon dioxide must 
 pass. 
 
 are best understood by studying the internal and external 
 
 structure. 
 
 Internal Structure. The wall of an air cell consists of 
 
 elastic connective tissue lined with a layer of very flat and 
 thin epithelial cells (Fig. 150). This 
 lining is continuous with the epi- 
 thelial lining of the bronchial tubes. 
 It is so thin as to offer almost no 
 obstruction to the passage of oxy- 
 gen out of the cell and the entrance 
 of the carbon dioxide from the blood 
 vessel (Fig. 151). 
 
 It must be remembered that mu- 
 cous membrane lines all cavities in 
 the body accessible to the air. Al- 
 most all of the nose and pharynx, 
 and all of the trachea and bronchial 
 
 tubes, as far as the lobules, are lined with a mucous mem- 
 brane the cells of which are furnished with cilia (Fig. 152). 
 
 These are minute hairlike filaments which are in constant 
 
 motion. When a few of the cells are examined under a 
 
 microscope, we 
 
 may see the cilia 
 
 in motion, even 
 
 for a time after sma/t Arteries 
 
 the removal of 
 
 the cells from the 
 
 body. They 
 
 make a quick 
 
 stroke upward, 
 
 and move back 
 
 more slowly, and 
 
 this is found to 
 
 give them the 
 
 power of moving 
 
 and Veins 
 
 Network of_ 
 CapiJ/arfes 
 
 FIG. 151. The blood vessels around two air cells. 
 
The Respiration 
 
 261 
 
 particles of dust which enter the lungs upward toward the 
 larynx. Upon reaching the larynx, the dust brings about 
 irritation which causes it to be coughed up. In the nasal 
 passages, they serve a similar purpose. At the opening of 
 the nostrils are also placed ordi- 
 nary hairs (hundreds of times 
 larger than cilia), which aid in 
 cleaning the air of dust as it 
 enters the nose. 
 
 Near where the trachea divides 
 into the two bronchi, the pulmo- 
 nary artery, bringing the dark blood 
 to the lungs, divides into two 
 branches, and the subdivision con- 
 tinues, until, finally, a network of 
 capillaries is formed around each 
 
 lobule, or cluster of air cells. These 
 
 ' FIG. 152. Ciliated cells 
 
 Capillaries are the termination Of from the trachea of a rabbit, 
 
 the branches of the pulmonary hi e hl y magnified, a, b c. mu- 
 
 cous cells in various stages of 
 
 artery, and the beginning of the secreting mucus, 
 pulmonary veins. It is here that 
 
 the blood changes from a purplish red to a scarlet red. A fine 
 connective tissue holds together all these air cells and tubes. 
 External Appearance. The entire cavity of the chest 
 except the space occupied by the heart and a few of its blood 
 vessels and the esophagus, is filled by the lungs and their 
 coverings. The lungs are light pink in early life but become 
 grayish and darker as age advances. This change is more 
 marked in persons who dwell in large cities or where the at- 
 mosphere is smoky and dusty. The lungs, or a part of one, 
 will float if thrown upon water. The right lung has three 
 lobes, or divisions, and the left, two lobes. The general 
 substance of the lungs consists of bronchial tubes, blood 
 vessels, lymphatics, and air cells, as above described, the 
 air cells being chiefly near the surface. 
 
262 Healthful Living 
 
 The surface of the lungs is in contact with the chest wall, 
 but it is not attached to the chest wall. It is held in con- 
 tact by the negative pressure* within the chest cavity. This 
 negative pressure during respiration varies from 755.5 mm. 
 of mercury on expiration to 752.5 mm. of mercury on in- 
 spiration. Its negativity therefore increases during inspira- 
 tion. Imagine a closed bag or sac made of thin membrane 
 lining the whole of the chest. Now imagine another closed 
 sac a little smaller, that is inside of, and lining, the first one. 
 Next imagine the lungs to be found inside the inner sac. Here 
 we have the lungs within the two membranes, called the 
 pleuras. The pleuras are in contact, so that the lung may be 
 said to be in contact with the chest wall. 
 
 The outer pleura lines the chest wall,- the inner pleura covers 
 the lung^. The two membranes form between them a closed 
 sac, a serous cavity which is air-tight and aids the lungs in 
 following the chest wall without friction when the chest ex- 
 pands. The two pleura! surfaces are in contact, and secrete 
 just enough fluid to enable them to glide smoothly upon 
 each other. But for the pleura there would be friction be- 
 tween the lungs and the chest walls. 
 
 The diaphragm and other muscles (Fig. 153). The floor 
 of the chest cavity is formed by a muscle that is the broadest 
 in the body, and also the thinnest -in proportion to its width. 
 It is called the diaphragm. It rounds up under the concave 
 base of the lungs somewhat like a dome and separates the 
 thoracic and abdominal cavities. It is attached to the 
 lowest ribs at the sides and to the lumbar vertebrae behind 
 (Fig. 153). Its rounded side is turned toward the chest, 
 and its hollow side toward the abdomen. It is the most im- 
 portant muscle of the respiratory system. When it con- 
 tracts, it flattens and descends, and the lungs descend with 
 it, thus lengthening and enlarging the cavity of the chest 
 from top to bottom. 
 
 When the diaphragm descends, it acts as a piston or a 
 
The Respiration 
 
 263 
 
 tight-fitting round board would act if pressed down into a 
 barrel of water. If there were two holes in the board (cor- 
 
 Infer/or Vena Cava 
 
 Diaphrej, 
 
 Sternum 
 
 'Kibs 
 
 D/aphracfm 
 Afuscu/ar Pi//ars 
 of the Ztfaphraqm 
 
 Esophagus 
 ^Aorta 
 Spfna/ Column 
 
 FIG. 153. The dome-shaped diaphragm. Name the large tubes 
 which pass through the diaphragm. 
 
 responding to the vena cava and the thoracic duct), the 
 water would be pressed up. Thus the circulation is aided 
 
 Vertebra/ Column 
 Mb 
 
 Outer Intercosta^ 
 Musc/es 
 
 Rib Cartilage 
 
 Sternum 
 
 Inner Intercostal^, 
 Muscles 
 
 FIG. 154. Figure A, showing three ribs, their attachment to spine and 
 sternum, and the muscles completing the thoracic wall. In B. the struc- 
 tures between the intercostals are shown. 
 
264 Healthful Living 
 
 by breathing. When the diaphragm relaxes, its thinness and 
 flexibility would allow it to drop downward, instead of spring- 
 ing upward as pupils sometimes suppose ; but the abdominal 
 walls contract as the diaphragm relaxes and force the liver, 
 stomach, etc., against the diaphragm, thus pressing it against 
 the lungs (Figs. 155, 156). 
 
 The chest walls can be lifted out at the sides and in front. 
 This is accomplished by muscles leading from the shoulders 
 and spinal column to the outer surface of the ribs, and 
 by the intercostal muscles, or the muscles that connect 
 each rib with the rib above (Figs. 154). Thus the chest 
 may be made deeper from front to back and from side to 
 side, and if the diaphragm acts at the same time, the chest 
 is elongated from top to bottom, and thus is enlarged in all 
 directions. 
 
 The breathing process. The breathing process serves 
 to carry into the lungs oxygen for the blood and to expel 
 the excess carbon dioxide given up to lung air by the blood. 
 The passing of the air into the lungs is called inspiration, and 
 the passing of the air out from the lungs is called expiration. 
 The two together constitute respiration, or breathing. 
 
 Inspiration. The lungs themselves contain no muscular 
 tissue, and therefore, they cannot expand by any force of 
 their own. Yet they expand when the chest expands. How 
 does the enlargement of the chest cause the lungs to expand, 
 and the air to rush in? The air cannot be pulled in, for it 
 has no cohesion, its parts do not stick together. It is found 
 that the air has considerable weight, for the height of the at- 
 mosphere* is at least forty miles, and the air above is pressing 
 down on that below. When the chest walls are moved out- 
 ward against the weight of the outer air (Figs. 155, 157), the 
 space in the chest is increased, and the air already in the chest 
 expands to fill the greater space. The air, when expanded, 
 is lighter, and exerts less pressure than before, and the denser 
 air outside, having greater pressure, presses inward until the 
 
The Respiration 
 
 265 
 
 air in the lungs is as dense as it was before the lungs were 
 enlarged. Thus do we allow the air to come into our lungs ; 
 we do not draw it in but make space for it, and the atmos- 
 phere outside presses it in. 
 
 Expiration. This is the reverse of inspiration. The 
 space within the chest is diminished, and the air in the lungs 
 
 Trachea 
 
 Sternum 
 
 Thachea 
 
 Sternum 
 
 FIG. 155. Inspiration. 
 
 FIG. 156. Expiration. 
 
 Diagrams to show the positions in respiration of the sternum, diaphragm, 
 and abdominal wall. 
 
 is compressed and becomes denser than the air outside. This 
 denser air has greater pressure than the outside air, and 
 presses out through the air passages until enough has passed 
 out to restore the equilibrium, making the pressure equal 
 without and within (Fig. 156). 
 
 In ordinary quiet expiration, the lungs become smaller, 
 owing chiefly to the elasticity of the parts involved. When 
 the air rushes in during inspiration, it fills the enlarged 
 
266 
 
 Healthful Living 
 
 air cells and the walls being made parity of elastic tissue, 
 the cells contract again when the muscles of inspiration 
 cease to act. When the ribs are lifted up during inspira- 
 tion, the costal cartilages that connect them with the 
 sternum are slightly bent, and the elasticity of these carti- 
 
 lages, as well as the weight 
 of the chest wall, causes the 
 ribs to become lower when 
 the muscles of inspiration 
 cease to act. Many pupils 
 get the erroneous idea that 
 the diaphragm is also elastic 
 and pushes upward when it 
 relaxes, thus aiding expira- 
 tion. When relaxed, it has 
 no more elasticity than a 
 piece of cloth, and no power 
 to push itself upward. It 
 should be remembered that 
 muscles never push ; they 
 always pull by drawing their 
 
 FIG. 157. Diagram of first and 
 
 origin * and insertion * nearer. 
 
 . . 
 
 seventh ribs, in connection with the However, the abdomen has 
 spine and the sternum, showing how 
 in inspiration the latter is carried 
 upward and forward. The expira- 
 
 somewhat Compressed, 
 . . , 
 
 and its Walls Somewhat 
 
 tory position is indicated by con- stretched during the inspira- 
 
 tinuous lines, the mspiratory by . 
 
 broken lines. tion. When the diaphragm 
 
 relaxes, the elasticity of the 
 
 muscular walls of the abdomen presses the organs against 
 the under side of the diaphragm, pressing that in turn against 
 the base of the lungs, and aiding expiration. 
 
 Quiet or passive expiration is, therefore, a rebound brought 
 about by the elasticity of the air cells, costal cartilages, 
 and abdomen, and by the weight of the chest wall. Active 
 expiration adds muscular contraction to the above forces. 
 
The Respiration 
 
 267 
 
 The two layers of intercostal muscles are among those 
 used in inspiration and active expiration (Fig. 158). 
 When the upper ribs are held, the contraction of the 
 intercostals raises the ribs; when the lower ribs are 
 fixed, the contrac- 
 tion depresses the 
 ribs. The 'inter- 
 costals act to raise 
 or depress the ribs, 
 depending upon 
 the fixation of the 
 ribs above or be- 
 low. In active 
 expiration the ab- 
 dominal walls con- 
 tract and press 
 the abdominal or- 
 gans against the 
 diaphragm, thus 
 pressing upward 
 on the lungs. 
 
 Ease in breathing. By studying the skeleton of the chest, 
 carefully observing the bones and cartilages, and by ex- 
 perimenting upon his or her own breathing, the pupil is 
 to fill out the following reasons why expansion and con- 
 traction of the lower chest (abdominal breathing) is easier 
 than breathing with the upper chest (costal breathing). 
 
 1. There are two pairs of ribs below, while there are 
 
 none above. 
 
 2. There are three pairs of - ribs below, while there 
 
 are none above, but all the ribs of the upper chest are 
 
 ribs. 
 
 3. The joints between the seven pairs of true ribs and the 
 sternum are more flexible below because - . 
 
 4. In abdominal breathing the breaths will not have to be? 
 
 FIG. 158. Diagram to show action of inter- 
 costal muscles on inspiration and expiration. At 
 A two ribs (a-b and d-c) are represented in passive 
 position. The two ribs move at the fixed points, 
 6 and c. When the ribs are raised notice that the 
 line a d, which represents the sternum, is farther 
 from the spine b c, as in C, and nearer when de- 
 pressed, as in B. This obliquity of the ribs per- 
 mits the increase in the depth of the chest on 
 inspiration and decrease in expiration. 
 
268 Healthful Living 
 
 so frequent to supply the same amount of air, because the 
 
 lower chest, besides being more flexible, is than the 
 
 upper chest. 
 
 5. The bones of the rest upon the upper chest. In 
 
 upper chest breathing their weight, and the weight of both 
 of the , must, therefore, be lifted. (Test by experiment.) 
 
 The air we breathe. Air is composed of a mixture made 
 up chiefly of oxygen, nitrogen, and a very small quantity of 
 carbon dioxide. Nitrogen is colorless, tasteless, and odorless ; 
 it does not support combustion, and is one of the most in- 
 active gases known to chemists. The oxygen of the air is 
 also colorless, tasteless, and odorless, but it is one of the 
 most active gases known to chemists. The air exhaled con- 
 tains about the same amount of nitrogen as that inhaled, 
 but it contains much less of oxygen, the latter having been 
 replaced by an almost equal quantity of carbon dioxide. 
 
 Composition of the air. One hundred parts of pure air 
 contain about 20 parts of oxygen, nearly 80 parts of nitro- 
 gen (and other gases), and .04 of a part of carbon dioxide. 
 Air coming from the lungs contains 16 parts of oxygen, nearly 
 80 parts of nitrogen, and over 4 parts of carbon dioxide. The 
 air while in the lungs has lost 4 parts of its oxygen, there 
 has been no essential change in the quantity of nitrogen, 
 and it has gained 4 parts of carbon dioxide. The oxygen 
 is in the air in order to supply an element to animals essential 
 to their activity. The nitrogen in the air is not used in the 
 body. The small amount of carbon dioxide in the air sup- 
 plies the plants with carbon. Its quantity is being con- 
 stantly added to by fires and by the breath of animals. The 
 leaves of plants, aided by the sunlight, are constantly re- 
 moving it, so that it is kept at .04 of one per cent in the air. 
 
 Foul and fresh air. It has been believed for many years 
 that the cause of bad air was the presence of carbon dioxide 
 coming from the lungs. At one time it was supposed 
 that the air of crowded rooms contained an unknown poison. 
 
The Respiration 269 
 
 To-day, because of many studies, it is known that the 
 carbon dioxide plays a very small part in contaminating the 
 air of rooms and most of the foulness of air is due to a high 
 temperature,* high humidity,* and lack of air motion. Fresh 
 air means, therefore, not more oxygen or more " ozone/ 7 
 but air of low temperature, low humidity, and in motion. 
 Eastman and Lee have shown that the pulse rate will in- 
 crease from 67 to 106 as the temperature of the air rises 
 from 74 to 110 F. and the humidity from 68 to 90. People 
 must recognize these facts and adopt their way of living to 
 conform to the knowledge we have. As a rule, the house 
 is overheated, and in steam-heated rooms the humidity is 
 too high. It is to be remembered that hot, humid, still air 
 is to be avoided. The windows in the room should always 
 be open sufficient to allow the air of the room to keep in 
 gentle but continuous motion, the humidity to remain like 
 that of the air out of doors and the temperature not above 
 68 F. 
 
 The hygiene of respiration. Statistics* indicate that 
 among civilized races a large proportion of the deaths is due 
 to lung diseases. This proportion is frequently estimated as 
 high as one seventh of the entire number. For this reason, 
 it is important to care intelligently for the respiratory system. 
 
 The cilia of the air passages stop most of the dust before it 
 reaches the lungs, but not all. If the dust is excessive, mil- 
 lions of particles enter the lungs. If a housekeeper would 
 examine the air of the room with a beam of light reflected by 
 a mirror during the time of sweeping, she would often be 
 horrified, and would heed the caution of those who say that 
 every door and window should be opened before beginning to 
 sweep, and allowed to stay open for two hours afterward. 
 If there is a breeze, so much the better ; it blows the dust 
 out, especially if she sweeps in the direction of the breeze. 
 It is the presence of dust floating in the air, more than frag- 
 ments of trash upon the floor, that makes a dirty home. 
 
270 Healthful Living 
 
 When the carpet is swept, dust comes from the carpet it- 
 self, especially if it is old. Curtains and hangings also hold 
 dust. Hardwood floors, with rugs instead of carpets are 
 recommended, and oilcloth and linoleum are also excellent 
 substitutes for carpets. Rugs can be conveniently cleaned 
 at any time, and the floor can be cleansed with a moist cloth. 
 
 Breathing through the nose. (1) On account of the pro- 
 jections of the turbinate* bones and processes into each nasal 
 passage and the roundabout way the air takes in passing 
 through the nose instead of the mouth, nasal breathing brings 
 the air in contact with a much larger extent of moist and 
 warm mucous membrane than does mouth breathing. The 
 air becomes warm and does not, like cold air, irritate the 
 trachea and bronchial tubes. (2) The air becomes purified, 
 because the hairs just within the nostrils and the mucous 
 lining of the latter serve to catch particles of dust. 
 (3) While a mouth breather is eating, sufficient time is not 
 taken for chewing the food, but it is swallowed too soon, so 
 urgent is the necessity for breathing. (4) In the habitual 
 mouth breather, the nasal mucous membrane, from lack of 
 stimulus of the cold air, dries and shrinks, causing discom- 
 fort; and since, in its dry condition, the circulation easily 
 becomes obstructed, there is a predisposition to congestion 
 and catarrhal nasal affections and injury to hearing. (5) An 
 unpleasant expression of the face results from mouth breath- 
 ing (Fig. 78). The lower jaw recedes, the upper teeth pro- 
 ject, the nostrils are not developed and in a grown man may 
 be no larger than during childhood. (6) A person has 
 greater endurance in muscular exertion if he breathes strictly 
 through the nose. He can hold out much longer, his lungs 
 are kept more expanded, and the heart is not oppressed ; 
 and, after a while, a " second wind " comes to him, for 
 instance, during running. (7) The voice has more reso- 
 nance if the nasal passages are open. 
 
 A Scotch physician, fully appreciating the importance of 
 
The Respiration 27 1 
 
 proper breathing, has written a valuable medical paper, 
 entitled, " Shut Your Mouth and Save Your Life." Some- 
 times the cause of stopping up the nose in children is en- 
 largement through growth of glandlike structures in the 
 upper part of the pharynx, called adenoids. They are just 
 behind the posterior openings of the nasal passages, and can 
 be easily removed if they become enlarged. Persons who 
 sleep with the mouth open are likely to snore, and to awake 
 in the morning with the mouth and throat dry. 
 
 Muscular action in breathing. Expand your lungs, and 
 see whether they will contract of themselves. Contract 
 your lungs and see whether they will expand of themselves. 
 See whether you can make waist, chest, and abdomen ex- 
 pand at the same time. You learned that the periods of 
 rest taken by the heart muscles amount to how many hours 
 daily? The breathing muscles also rest a considerable 
 portion of the time ; with calm and happy people they rest 
 more than with people of anxious, unquiet dispositions. We 
 can breathe by means of the expiratory muscles alone or by 
 means of the inspiratory muscles alone, or by using each set 
 alternately. When all the breathing muscles are relaxed, 
 the lungs are at rest in what may be called the neutral 
 position, since there is neither voluntary contraction nor 
 expansion. In this position they are of about average size. 
 If now we use the expiratory muscles and contract the lungs, 
 the muscles may relax during inspiration which follows, for 
 it will be accomplished by the elasticity of the abdominal 
 walls and organs, and of the cartilages of the thoracic cage ; 
 for these were bent when the cage was pulled from the 
 neutral position. Try this method of breathing for a few 
 minutes. 
 
 Or, on the other hand, when the lungs are at rest, we may 
 breathe by using the inspiratory muscles (Fig. 160) (dia- 
 phragm and intercostals) , thus expanding the lungs from the 
 neutral position, and allowing the muscles to rest, while the 
 
272 
 
 Healthful Living 
 
 \ 
 
 FIG. 160. 
 
 elasticity of the parts forces out the air. Try breathing in 
 
 this way. 
 
 This expanded breathing has the advantage, over con- 
 
 tracted breathing, of removing pressure from the heart and 
 
 large blood vessels in the chest, and allowing the heart to 
 
 work with greater free- 
 dom. It also keeps the 
 lungs more expanded. 
 You learned in another 
 paragraph that it is the 
 usual method of quiet 
 breathing ; but strong, 
 contracted breathing 
 sends out fouler air from 
 deep in the lungs , 
 
 In both of these ways 
 of using the breathing 
 muscles, there is a pause 
 
 Diagrams illustrating improper and ,t npntrfll nnsitirm 
 proper methods of breathing. Dotted 
 
 lines show area of expansion. before the next breath. 
 
 FIG. 159. Here, owing to faulty pos- R , f - f f 
 
 ture, expansion of chest is impeded and 
 breath is taken by the "diaphragmatic exertion, as when run- 
 
 ning, Or during a time of 
 excitement and in some 
 
 f orrnc , n f ill npss fhprp is 
 QeSS ' l 
 
 no pause between breaths, 
 and we use what may be called forced breathing. 
 
 Respiratory exercises. It has been stated that strong 
 contracted breathing sends out foul air from deep in the 
 lungs. Some people argue from this fact that we can re- 
 move the waste material by deep breathing, and some even 
 go so far as to say that by breathing exercises we can get 
 strong and vigorous. Now our physiology must help us at 
 times when methods of getting health are proposed. It is known 
 in the first place that the body does not store up oxygen in 
 
 FIG. 159. 
 
 Fm 160. -Figure properly poised 
 and free from constriction. Here the 
 entire thorax can move freely, and natural 
 breathing is the result. 
 
The Respiration 273 
 
 the body but takes in oxygen only in response to the needs 
 of the body. If one stands at the window and breathes for 
 15 minutes will more oxygen be taken into the body? We 
 have learned also that the rate and depth of respiration are 
 governed by the amount of carbon dioxide in the blood, and 
 when this gas is increased the respiration is increased in 
 order to remove the waste. If we desire the effect of breath- 
 ing exercises, we should engage in some game or activity 
 that will make us breathe much faster. In this way our 
 respirations will increase without our thinking about them, 
 and in addition we will get the other desirable results of the 
 activity. 
 
 There are some people whose chests are so small that they 
 are unable to engage in any vigorous sport because their 
 lungs are not developed enough to supply the required oxy- 
 gen. Such persons need breathing exercises to increase the 
 mobility* of the chest but in addition they need forms of 
 activity like games, also running in the case of boys, and 
 skipping in the case of girls. The improper ways of breath- 
 ing that are seen are due to faulty methods of dress, and if 
 these are corrected a great improvement will be noticed. 
 
 Abdominal Breathing, Chest Breathing, and Natural 
 Breathing. It should be remembered that breathing is a 
 natural process. It is not necessary to teach animals to 
 breathe. A race horse, needing a very efficient respiratory 
 mechanism, breathes without being taught. The breathing 
 process is natural in man. It is true that he may breathe 
 with difficulty because of constricting clothing or poor 
 posture, but the correction of the conditions causing the defect 
 should be made rather than an attempt to teach some fancy 
 method of breathing. 
 
 There has been much discussion among physicians, voice 
 trainers, and elocutionists as to the proper way to breathe, 
 some advocating chest breathing, and some advocating ab- 
 dominal or diaphragmatic breathing (Fig. 159). The fact 
 
274 Healthful Living 
 
 that so elementary a process as breathing is still a subject 
 of discussion illustrates how imperfect is the state of our 
 physiological knowledge, especially when an attempt is 
 made to apply it to practical purposes. The author believes 
 that pure chest breathing and diaphragmatic breathing are 
 both wrong, and that what may be termed natural breath- 
 ing is the method to teach when corrections are to be made 
 (Fig. 160). 
 
 Natural breathing employs movement of both chest and 
 diaphragm, the greatest expansion being in neither chest nor 
 
 abdomen, but at the waist (Fig. 
 
 *yVY v/v ^A/l/)/l/1 (\ 161)? an d diminishing in amount 
 Men both upward and downward. 
 
 / T/y*|/|/"jyV vx ^ N ^ y ^^^ The objection to pure chest 
 Woman fn Corset breathing is that the marked 
 
 movement of the upper part of 
 the bony cage requires exhaust- 
 ing effort; such movement can 
 'Man m Corset be employed without waste of 
 
 strength for only a short period, 
 as in gasping for breath or during 
 great muscular exertion. 
 
 In natural breathing, the dia- 
 
 F.O. 161. -Breathing trac- phragm contracts but at the same 
 ings (Kellogg) . Motion of chest time the ribs are lifted upward 
 
 recorded at left and of waist at j outward flnrl tVp nnint; of 
 
 right. Interpret these tracings anCl outwaro -> and tne P omts ot 
 
 by what is shown in Fig. 160. attachment of the diaphragm 
 
 are thus raised and separated so 
 
 that the diaphragm flattens without any great descent. 
 But in pure abdominal breathing, the movement is con- 
 fined to the diaphragm and abdomen, and lateral action 
 of the chest is suppressed (Fig. 159). The effect of this 
 is to cause too great a displacement downward of the 
 liver, stomach, kidneys, colon, and other organs. But in 
 natural breathing, any great degree of downward movement 
 
The Respiration 275 
 
 is prevented by expansion of the trunk at the waist. In 
 abdominal breathing, the abdominal walls are entirely re- 
 laxed as the diaphragm descends, and the liver and other 
 organs are moved but not compressed. In natural breath- 
 ing they are compressed and slightly moved, and the com- 
 pression squeezes the blood out of them toward the heart 
 and presses the lymph upward, through the thoracic duct ; 
 the expansion of the chest at the same time helps to draw 
 the blood upward. During expiration fresh blood is sent 
 back to the abdominal organs, and so they are kept fresh 
 and strong. Women who wear skirts with bands tight enough 
 to support them at the waist, gradually lose the power of 
 lifting the ribs outward at the waist. This expansion is 
 most important for good breathing, because the lungs are 
 largest there. The belt used by men for supporting the 
 trousers, should rest on the hip bones (ilium) and not above 
 them. 
 
 Ventilation* The evil effects of rebreathirig air can 
 hardly be exaggerated. The blood stagnates, the heart acts 
 slowly, the brain is clogged, the head aches, and either a dull 
 or a feverish feeling arises. The body becomes sensitive to 
 cold. The skin becomes pale, the blood is loaded with im- 
 purities, and the whole body is obstructed with refuse ma- 
 terial. In such a human body, colds, catarrh, consumption, 
 and other diseases readily develop. The constant breathing 
 of even the slightly impure air of most private houses can- 
 not but tend to undermine the health and prevent that 
 perfect soundness of body which thorough ventilation or life 
 in the open air insures. 
 
 Judgment with regard to ventilation is rare. In many 
 churches and assembly rooms the windows are tightly closed 
 except in warm weather. If, during the meeting, the room 
 becomes too warm, some one will open one or more windows 
 to their full height ; the strong draught soon cools the room 
 and chills some one, whereupon he goes to the window and 
 
276 Healthful Living 
 
 shuts it tight. One absurd extreme thus follows another. 
 All that was necessary, if there was no scientific provision 
 for ventilation, was for all of the windows to have been 
 opened, for an inch or less, when the assembly began, and 
 allowed to remain so ; then no one would have been too hot 
 or too cold, or would have suffered from vitiated* air. 
 
 The ventilation of the schoolroom is often deplorable. 
 A visitor, upon entering a schoolroom, especially if the 
 school has been in session for an hour or more, may notice 
 a stifling, foul-smelling atmosphere. The children have 
 rushed in from their active games with their clothing satu- 
 rated with perspiration. Their healthy skins perspire more 
 freely than do those of adults. Some of them may have 
 coughs or colds, some may have come from sick rooms. The 
 dust from the pattering of many feet, the clouds of chalk 
 dust, accumulate until they become almost unbearable, and 
 all that gets out leaves the room on the clothes of the pupils, 
 or on the mucous membrane of their nasal passages and 
 lungs ; for the janitor is more ignorant usually than the 
 housekeeper, and unless forced to do so he will not open 
 the windows before sweeping because of the trouble; or, 
 if persuaded to open them, he must be compelled by the 
 principal to allow them to remain open for the dust to blow 
 out, otherwise he will close them on leaving each room to 
 avoid the annoyance of returning. 
 
 These are the conditions of many, many schoolrooms and 
 homes, for, unfortunately, some persons' knowledge of physi- 
 ology is never put into practice. It is not strange that 
 lung troubles are common and that people, ignorant of their 
 cause, take " patent medicines " instead of pure air. Many 
 of the Indians of Patagonia died of consumption within nine 
 months after being taught by the missionaries to live in 
 houses. The missionaries neglected to tell them how to live 
 in houses. 
 
 It is necessary to give children knowledge of the geography 
 
The Respiration 
 
 277 
 
 of Africa and other remote lands, but it is at least as neces- 
 sary to train them to sit and to stand correctly. Frequent 
 periods of relaxation and play would help to counteract the 
 deforming effects of prolonged sitting, would help them to 
 grow up well-formed men and women, and would make 
 them more ready to learn the geography as well. 
 
 The health of children at school often suffers, and parents 
 usually think it is because of the number of studies. This 
 
 FIG. 162. The proper method of ventilating a room with stove. The 
 stove is on the side toward the cold winds. The inlet is near the stove, 
 the outlet farther away. If the window near the stove were lowered from 
 the top, what would happen? If another window near the stove were 
 opened, what might happen? If the prevailing cold winds came from the 
 opposite direction, what changes should be made in the room? How 
 do you ascertain whether the outlet fails to serve its purpose and become 
 an inlet? 
 
 idea is no doubt largely erroneous. The breathing of the 
 bad air, both at home and at school, the close confinement 
 in the schoolroom, sitting in a cramped position, and study- 
 ing by improper light, are the true causes in a majority of 
 cases. 
 
 Some persons in their anxiety for pure air become ex- 
 tremists, and forget that the body may likewise be injured 
 by cold. In ventilating a room, not one but two purposes 
 must be kept in view : to furnish air that is pure, and air 
 at the proper temperature. 
 
2 7 8 
 
 Healthful Living 
 
 Methods of ventilation depend upon the principle that 
 hot air is lighter than cold air and is pushed up by it. If 
 you have two openings for ventilation, one higher than the 
 other, at which opening does the warm air go out? If the 
 higher opening is near the ceiling, do the persons in the room 
 get the coldest or warmest air? Does such a method econo- 
 mize the fuel ? If the inlet is near the floor, why should the 
 stove be near the inlet? Why should 
 the outlet be on the side of the room far- 
 thest from the stove ? 
 
 Good ventilation is arranged so that 
 the fresh air shall be heated before or 
 just after it enters the room, and that it 
 shall pass across the room in order that 
 the inmates may get the benefit of both 
 its warmth and its purity before it passes 
 out (Figs. 162, 164). Test the direction 
 of the air currents in your bedroom and 
 in your schoolroom by means of a spider 
 web hanging from the end of a stick. 
 Why is it best not to have the outlet on 
 the side of the house toward the pre- 
 
 vailin s wind in winter? If the inlet is 
 
 so situated that the cold air does not 
 pass over the stove, a board or screen 
 may be placed before the window to deflect the current up- 
 ward and prevent its chilling those seated nearest the window 
 (Fig. 163). If you find by holding your hand near the inlet 
 that there is a good inward current, you may be sure there 
 is sufficient outlet ; although if it is not far enough from the 
 stove, heat will be wasted. If you know there is a strong 
 outward current, for instance when a fire is burning in an 
 open fireplace, you may be sure that the same amount of air 
 is entering somewhere, if only through minute cracks. 
 When over-enthusiastic people become interested in ven- 
 
 FIG. 163. Window 
 board prevents cold air 
 
 is directed upward. 
 
The Respiration 
 
 279 
 
 tilation, they sometimes injure themselves by chilling 
 draughts and low temperatures. The temperature of the 
 room should be kept between 65 and 68 degrees F. The fore- 
 going directions for ventilation apply to cold weather. For 
 warm weather no special directions are necessary, for most 
 people are more anxious to avoid unpleasant heat or the 
 possibility of soiling their collars with 
 perspiration, than they are moved 
 by the danger of breathing foul air. 
 
 The effect of tobacco on the respira- 
 tory organs. The hot smoke irri- 
 tates and dries the mucous membrane 
 of the mouth and throat, producing 
 an unnatural thirst that may readily 
 lead to the use of alcoholic drinks. 
 Inhaling the poisonous smoke, which 
 occurs to the greatest degree in 
 cigarette smoking, inflames the deli- 
 cate mucous lining of the bronchial 
 tubes and air cells. There may 
 result from this an irritating cough, 
 short breath, and chronic bronchial 
 catarrh. 
 
 FIG. 164. Stove for 
 rural school where furnace 
 is not used. The air en- 
 ters through a special inlet 
 
 General considerations. The hy- and is warmed as it passes 
 giene of respiration is only a phase throu s h a hood surround- 
 
 ,, , . ,. . ing the stove. 
 
 of the hygiene of living. All the 
 
 methods that are available to help people to live finer individual 
 lives and to preserve their strength and health for the welfare of 
 the race are valuable. Cleanliness of air is very important, 
 but cleanliness of living is more important. 
 
 Cleanliness. Nearly all people are very careful to wear 
 clothes that are perfectly neat and clean. Dust or mud upon 
 their clothes is considered the highest degree of uncleanli- 
 ness. Many think it of the highest importance to health 
 and refinement to keep the skin clean by regular baths. 
 
280 Healthful Living 
 
 But there are a few that think it of still greater importance 
 to keep the air clean that goes into the lungs. A few also 
 think it necessary to keep the alimentary canal pure through- 
 out by reasonable eating and living. We also meet with 
 those who believe not only that the clothes, the skin, the 
 lungs, the digestive organs, must be kept clean, but that the 
 blood must be clean and fresh, ever renewed by a strong and 
 vigorous flow, and they so live that as far as possible it shall 
 always be so. The daintily dressed lady or the dandified 
 man would be horrified at a particle of mud that fell upon 
 the clothes, but sometimes if you are so unfortunate as to 
 catch a whiff of the breath of such a person, its repulsive, 
 sickening odor shows that foulness and uncleanliness have 
 taken possession of the lungs, or digestion, or blood. We 
 should be careful to observe these five degrees of cleanliness, 
 but which should we value most highly? There is another 
 aspect of cleanliness that relates to the way the person lives. 
 It is concerned with thoughts and actions. What is the 
 relative value of these three : clean clothes, clean body, and 
 clean conscience? 
 
 The Mistake of the Over-studious. The pale student, 
 thinking only of the desire for learning aroused by teacher 
 or parents, and neglecting the promptings of his natural 
 instincts* toward complete living, thinks he is doing wisely 
 and right when he is constantly delving into books. On 
 the contrary, he is sinning against part of his nature and 
 unfitting himself for accomplishing the best work he is 
 capable of doing. 
 
 The Essential Unity of Body and Mind. All students 
 should remember the fact that the individual, particularly as 
 regards mind and body, is a unit and the health of the whole 
 is dependent upon the health and vigor of its parts. The 
 mind cannot achieve extraordinary success at the expense 
 of the body, without a loss of real health values in both mind 
 and body. Furthermore, it is important to remember that 
 
The Respiration 281 
 
 the brain, in its development from lower forms, followed 
 the development of the muscular system, and for this reason 
 we must always look to the muscular system as the founda- 
 tion upon which to build a safe and serene mind. This 
 does not mean that one should seek to develop large and 
 unsightly muscles with the hope of thereby achieving mental 
 power, but it does mean that bodily activity in physical forms 
 is. absolutely essential for the highest and finest development 
 of the brain and nervous system. The student in school or 
 college who seeks to be excused from physical education 
 classes is progressing in a direction which will bring a weak 
 and devitalized body unless he provides on the outside a 
 large and wholesome participation in games or sports. In 
 this day of interest in and plans for national preparedness, 
 it is the duty of the boys and girls of the nation to share 
 in this movement and bring to the service of the nation 
 in all fields of endeavor a finer body and a more vigorous 
 spirit. 
 
 APPLIED PHYSIOLOGY 
 
 Exercise I 
 
 1. State how in the case of a person of poor figure, a gradual 
 remolding of the cartilages, the strengthening of the muscles, and 
 the practice of chest lifting may each contribute toward acquiring 
 a correct and perfect figure. 
 
 2. How far is it in one's power to determine the shape and 
 appearance of his own body? 
 
 3. Give reasons why the weight of our clothing should hang 
 from the shoulders and not from the waist. 
 
 4. How can the hat be ventilated? (A punch for making 
 the hole costs a dime.) 
 
 5. Name habits that impair the power of the lungs. 
 
 6. How could you convince a person that a bedroom should be 
 open while and after it is swept? That it should be ventilated 
 at night? 
 
 7. Why do some persons " get out of breath " readily after a 
 meal? 
 
282 Healthful Living 
 
 8. Can a person become so used to bad air that he will not 
 notice it ? That it will not injure him ? 
 
 Exercise II 
 
 9. Which is the more offensive, the tobacco chewer, who 
 chiefly pollutes the ground, or the smoker, who pollutes the air? 
 
 10. Why are those who have pimples on the face likely to 
 multiply their number by picking and squeezing them with the 
 fingers? 
 
 11. Give the advantages of slow, deep breathing as compared 
 with quick, shallow breathing. 
 
 12. Why do those who stand up to hoe not get tired half as 
 quickly as those who bend or " hump " over? 
 
 13. Why do students who sit in rocking-chairs, or from other 
 causes lean the head forward when they study, often find that 
 they recover from drowsiness if they sit erect? 
 
 14. How are high collars a fruitful source of bad colds? 
 
 15. Is ventilation easier in winter or in summer? 
 
 16. If the draught up the chimney of the fireplace, when the 
 fire is burning, takes up a volume of air sufficient for many people, 
 why is it unwise to open a window? 
 
 LABORATORY EXERCISES 
 
 Experiment 1. To study modifications of the breath. 
 
 Study the following list of experiments with your own breath- 
 ing. Write after each word I or E according as inspiration or 
 expiration is chiefly involved in the action : 
 
 Sighing Coughing Sneezing 
 
 Sobbing Laughing Hiccoughing 
 
 Crying Yawning Snoring 
 
 Experiment 2. To study the mechanism of respiration. 
 
 Material. Respiration apparatus as show in Figure 165. 
 
 Method and observation. (a) Locate upon the respiration 
 scheme what corresponds to the following structures : 1 trachea. 
 2 glottis, 3 thoracic cavity, 4 lungs, 5 intrapleural space, 6 dia- 
 phragm. (6) Produce inspiration by lowering the diaphragm. 
 What happens to the lungs? What change occurs in the pressures 
 in the chest cavity? (c) Produce expiration by raising the dia- 
 phragm. Describe and explain what is noticed, (d) Close the 
 glottis and try experiments a, 6, and c. 
 
The Respiration 
 
 Experiment 3. To study the effect of 
 forced breathing. 
 
 Material. Watch with second 
 hand. 
 
 Method and observation. The sub- 
 ject, seated, breathes naturally and 
 counts the rate. Then breathes as 
 deeply as possible about 18 times a 
 minute. The attention should be 
 fixed on drawing deep inspirations. 
 Continue it for 30 seconds, at once 
 at the end of the 30 seconds count the 
 rate and compare this with the rate 
 before the experiment. 
 
 The deep inspirations removed the 
 excess of carbon dioxide from the blood, 
 and with this removed the stimulus 
 was less to the respiratory center in 
 the medulla and so the rate was 
 slowed. 
 
 Repeat the experiment for one 
 minute. 
 
 Experiment 4. To study forced breath- 
 ing without the excessive elimina- 
 tion of carbon dioxide. 
 
 Repeat experiment 3 while holding 
 a paper bag over the nose and mouth 
 of the subject. Record the results ob- 
 tained, compare with experiment 3 and 
 explain. 
 
 Experiment 5. To study the produc- 
 tion of apnea (period of no respi- 
 ration). 
 
 (a) At the end of a normal expi- 
 ration, the subject holds the breath 
 until no longer able to do so. How 
 long can it be held? 
 
 (6) Repeat experiment (a) after 
 taking a deep inspiration and counting 
 from the end of a normal expiration. 
 How long can it be held ? Is this period 
 longer or shorter ? Why is this so ? 
 
 FIG. 165. This apparatus 
 is made by -tying over the 
 bottom of the bell jar a sheet 
 of dental dam which has tied 
 in the center a marble for a 
 handle. The mouth is fitted 
 with a cork through which 
 passes a glass tube with stop 
 cock. At one end of the glass 
 tube is tied a small rubber 
 bag. When the tube is in- 
 serted in the jar and the cork 
 put in place the rubber dia- 
 phragm should be pressed up- 
 ward as it is iri the human 
 body. 
 
284 
 
 Healthful Living 
 
 Experiment 6. Respiration may be 
 studied by means of the appa- 
 ratus shown in Figure 166 ob- 
 tained from the Harvard Appa- 
 ratus Company, Back Bay Post 
 Office, Boston, Massachusetts. 
 
 GLOSSARY 
 
 Atmosphere. The gaseous mass, 
 chiefly air, that surrounds the 
 earth. This mass* at sea level 
 will support a column of mer- 
 cury 30 inches high at a tempera- 
 ture of C. This pressure is 
 sometimes stated as being equal 
 to 15 pounds to the square 
 inch. 
 
 Humidity. Refers to the moisture 
 in the atmosphere. This mois- 
 ture varies and two terms are 
 used to express the relation as 
 it exists at different times. 
 Absolute humidity. The amount 
 of water vapor in the air ex- 
 pressed in the number of 
 grains of moisture per cubic 
 foot of air. 
 
 Relative humidity. The ratio of 
 the actual quantity of mois- 
 ture in the air to the quan- 
 tity that would saturate it at 
 the temperature and pressure 
 of the air at that time. 
 
 Insertion. The point or points of attachment of a muscle 
 to a bone. The insertion, as contrasted with the origin, 
 the other attachment, is considered as more movable. 
 Another distinction between insertion and origin is .that 
 the latter is on the bone nearer the center of the body, 
 and the insertion further from the central part of the 
 body. 
 
 FIG. 166. The respiration 
 scheme. About one third the 
 actual size. (Harvard Appa- 
 ratus Co., Boston.) The water 
 diaphragm is made to move up 
 and down and causes a filling of 
 the rubber bag. The water is 
 moved by means of water in 
 connection with the tube at the 
 bottom of the picture. The 
 left-hand mercury U-tube shows 
 the change of pressure within 
 the interpleural space ; the other 
 U-tube shows the change in 
 pressure within the lung. 
 
The Respiration 285 
 
 Instinct. A natural, spontaneous impulse moving to action with- 
 out the intervention of reason. This impulse acts most 
 powerfully in connection with preservation and development. 
 
 Mobility. The quality of being freely movable. 
 
 Negative pressure. The pressure of the atmosphere in millimeters 
 of mercury is 760. A pressure less than 760 mm. of mercury 
 is a negative pressure. 
 
 Origin. One of the points of attachment of a muscle to a bone. 
 It is attached at the more stationary part of the bone or is 
 nearer the central part of the body. 
 
 Statistics. A mass of facts pertaining to a body of things, system- 
 atically gathered, classified, and tabulated. Statistics are 
 essential in the conduct of a large business, in manufacturing 
 and in all scientific studies. 
 
 Temperature. The condition of the body or thing as regards 
 heat and cold. 
 
 Turbinate. Top-shaped. The turbinate bones of the nose are 
 of this shape. 
 
 Ventilation. The process of providing free circulation of air. 
 
 Vitiated. Refers to air. To vitiate is to injure the qualities. 
 Vitiated air is air that has lost the qualities of freshness, of 
 freedom from dust and bacteria, and is not of the proper tem- 
 perature and moisture. 
 
CHAPTER XV 
 THE NERVOUS SYSTEM 
 
 I. The Functions of the Nervous System. 
 Communication 
 Coordination 
 
 II. The Nerve Cell the Unit of the Nervous System. 
 Dendrites 
 Axone 
 Neuron 
 Ganglion 
 Nerve center 
 Neuroglia 
 
 Terminations of nerve fibers 
 Efferent, afferent, and association fibers 
 
 III. Nerve Action. 
 
 IV. Sensations. 
 
 General 
 Special 
 
 V. Injury to Nerves. 
 
 VI. General Arrangement of the Nervous System. 
 The spinal cord 
 The autonomic system 
 The brain 
 
 The functions of the nervous system. Communication. 
 The amoeba and other one-celled animals need no nervous 
 system, but the larger animals, consisting of a colony of 
 cells, as it were, need a means of communication between 
 the cells, in order that their life may be harmonious. On 
 Robinson Crusoe's island a telephone or a post office system 
 would have been of no use, but a number of individuals 
 living together and practicing a division of the labor of the 
 
 286 
 
The Nervous System 287 
 
 community for their mutual advantage, are compelled to 
 communicate with each other in order to make their wants 
 known. The lowest of the many-celled animals, such as the 
 sponges, have no cells specially set apart for carrying messages 
 between the cells, but each cell passes the impulses it re- 
 ceives to its neighbor cell. This will do for a small and 
 simple community of cells, but a larger community, like 
 one of the higher animals, possesses certain cells, called nerve 
 cells, whose chief function is to keep up the communication 
 between the cells. In the chapter on nerve tissue you learned 
 that the nerve cells did this by means of branches, which in 
 some cases are several feet long. 
 
 Coordination. Did you ever see a crowd of people at a 
 fire when a neighbor's house was burning? Everybody 
 ran out, yet very little was done. Everybody shouted 
 orders which nobody obeyed. But on the arrival of the 
 chief of the fire department or the head of a fire company, 
 who had had experience in the control of men fighting a fire, 
 the scene changed ; valuable property was saved, and the 
 fire was stopped. 
 
 Every community has certain deliberative and controlling 
 bodies ; these may be a board of aldermen, a court of jus- 
 tice, a legislature, or a congress. In a similar way the great 
 number of individual cells which make up the human body 
 must be controlled by some central power, or they will not 
 work in harmony; nothing will be accomplished, but a 
 state of anarchy and helplessness called disease will follow. 
 The seat of this central controlling power is located in the 
 brain. 
 
 The nerve cells receive, modify, and send out impulses. 
 By these three kinds of acts the nervous system accomplishes 
 what is called coordination. This term signifies not only 
 that the cells work together at the same time, but that they 
 work together as a part of a plan for the accomplishment 
 of some definite result. Suppose that a man sees a bright 
 
288 Healthful Living 
 
 dollar on the road and picks it up. In order that he may 
 do this, the cells receiving through the optic nerve the im- 
 pression of the shining coin must be in communication, 
 either directly or indirectly, with the muscles of the hand ; 
 and that the hand may reach the coin, the muscles of the 
 arms, legs, trunk, head, and neck must act together. Even 
 the heart and respiratory muscles must modify their action 
 somewhat to suit the movement. 
 
 Other Organs besides Muscles Must Be Coordinated. 
 Suppose a boy sees a large red apple. He notices the odor 
 which tells him it is ripe, and his " mouth waters " for it ; 
 that is, the salivary glands begin to work, even before he 
 puts the apple to his mouth. The chewing and swallowing, 
 the secretion and peristalsis in the digestive organs, are all 
 carried on under the control of impulses that reach them 
 through the nerves. Without these impulses, the salivary 
 glands would not work when the mouth was chewing the 
 food ; the dry food would stick to the esophagus and have 
 to be washed down with water ; the gastric juice would not 
 be secreted at just the right time ; the food would ferment 
 in the stomach, and the person would soon be ill. 
 
 The nerve cell the unit of the nervous system. You 
 learned when studying the tissues that the nervous system 
 consists of nerve cells with their branches, called nerve fibers. 
 Nerve cells are microscopic bits of protoplasm, like other 
 cells, yet they are remarkable among animal cells for their 
 large size. Some of the cell bodies in the spinal cord are so 
 large as to be almost visible to the unaided eye, and they 
 have branches leading from the cord to the hand or foot. 
 Each cell contains a nucleus, within which is a nucleolus 
 (Fig. 167). Nerve cells are the most remarkable in the body 
 for irregularity of shape (Fig. 176) ; some of them have so 
 many branches that they have a starlike appearance. 
 
 Dendrites* The dendrites are branches of nerve tissue 
 from the cell body. The dendrites of a nerve cell are the 
 
The Nervous System 
 
 289 
 
 treelike branches which bring impulses to the cell (Fig. 31). 
 Through the dendrites the cell may be in communication 
 with numerous other cells. A branch of one cell does not 
 join the branch of another cell. It has not yet "been settled 
 by physiologists whether the ends of the dendrites of com- 
 municating cells actually touch. 
 
 The axone and its parts. In most of the fully developed 
 nerve cells, one of the branches is very greatly prolonged 
 as a fine thread of protoplasm, which becomes the core of a 
 nerve fiber (Fig. 167). Every nerve fiber has such a core. 
 
 Axis Cyftnde. 
 
 Afettuttery Sheath 
 
 WucJeus 
 -JVeuroyJfa Cell 
 
 FIG. 167. Nerve cell showing axone, medullary sheath, and field 
 of fibers. 
 
 In most of them this central thread of protoplasm becomes 
 covered with two coats (Fig. 32) ; an outside protective coat 
 forms a tube, called the connective sheath, and between the 
 walls of this tube and the central thread is a coat of semi- 
 liquid, fatty substance called the medullary sheath, which, 
 shining through this outer sheath, gives a silvery white ap- 
 pearance to the fiber. Such fibers are called medullated* 
 fibers, or white fibers. Some fibers lack the medullary 
 sheath, and are called non-medullated, or gray fibers. 
 
 Neuron* One nerve cell together with all its branches, 
 both dendrites and axone, is called a neuron. A neuron is 
 the unit, and the nervous system is built up of an enormous 
 
2 9 
 
 Healthful Living 
 
 number of these units, together with supporting tissue 
 (Fig. 167). 
 
 Many nerve fibers may be bound together by connective 
 tissue until they form a cord large enough to be seen by the 
 unaided eye (Fig. 168). A bundle of nerve fibers is called 
 a nerve. The sciatic nerve in the thigh is as large as the 
 end of the little finger. The fatty sheaths of the fibers are 
 supposed to insulate the fibers so that 
 a nerve impulse cannot go across to 
 another fiber ; they serve the same pur- 
 pose as -the insulating substances with 
 which wires used to conduct electricity 
 are sometimes coated. As a rule, a 
 large nerve accompanies an artery down 
 the inside of each limb, and across the 
 joint on the side toward which the limb 
 bends. Thus they are well protected. 
 One exception to this is a nerve cord 
 which crosses the elbow on the side 
 away from which the elbow bends. 
 Therefore, it is sometimes hit, and the 
 end of the bone there is called the funny 
 bone because of the tingling sometimes 
 felt, as if it were in the hand at the 
 termination of the nerve. 
 
 Ganglion. The cells are not scat- 
 tered singly throughout the nervous 
 system but are gathered into groups. This seems to afford 
 easier communication from one cell to another through their 
 branched dendrites, which are unusually short. One such 
 group of cells situated outside the cord is called a ganglion. 
 Ganglion is not to be confused with the term " nerve 
 center," which relates primarily to function. The term 
 ganglion refers to structure. 
 
 Nerve center. PL group of nerve cells, situated in the 
 
 FIG. 168. Section 
 of two nerves, show- 
 ing many nerve fibers 
 bound together in con- 
 nective tissue sheaths, 
 to make nerves. 
 
The Nervous System 291 
 
 brain or spinal cord, performing a definite function, such as 
 controlling the muscles of breathing, form what is called a 
 nerve center. The brain consists of a number of large nerve 
 centers with their connecting fibers. There are many nerve 
 centers in the spinal cord also. Where nerve cells, ganglia 
 and gray fibers are abundant, the nerve substance is 
 gray ; where medullated fibers with their hidden gray cores 
 are abundant, the nerve substance is white in appearance. 
 This led anatomists and physiologists in times past to classify 
 nerve substance as gray matter and white matter. 
 
 Neuroglia. The fibers and cells of both the gray and the 
 white matter are held in place by a tissue called neuroglia, 
 which is composed "of extremely fine fibers and minute cells. 
 Though like connective tissue in function, its chemical com- 
 position is different; nor is neuroglia developed from con- 
 nective tissue (Fig. 167). 
 
 Terminations of nerve fibers. If we could trace toward 
 the central nervous system the course of the various nerve 
 fibers in a nerve like the great sciatic, for example, we should 
 find that every one of its thousands of nerve fibers ends, with- 
 out exception, in a nerve cell in the spinal cord or brain, 
 or in any one of the ganglia near the central nervous system. 
 If we should trace these same fibers away from the central 
 nervous system, they would be found to have various endings. 
 Some enter the muscles where they subdivide, and finally 
 end in the muscle cells. Others follow the blood vessels 
 and end in the muscle fibers forming the middle layer of 
 their walls. Others go to the gland cells ; for example, the 
 sweat glands in the skin. Others, passing to the skin, 
 terminate at the roots of the hair, or in curious little bodies 
 composed of cells and called touch corpuscles (Figs. 169, 
 170). Depending upon its function every nerve fiber ends 
 centrally in a nerve cell or peripherally * in either a muscle 
 cell, a gland cell, or a sense organ cell. Fibers that end cen- 
 trally are sensory and carry impulses to the brain or cord ; 
 
2Q2 
 
 Healthful Living 
 
 fibers that end peripherally are motor or secretory and carry 
 impulses from the brain or cord. 
 
 Efferent,* afferent* and association* fibers. Fibers that 
 connect nerve cells with muscles or glands are called effer- 
 ent (outward bearing) fibers ; (they may be motor or secre- 
 tory) ; those that connect nerve cells with sense organs are 
 called afferent (in bearing) fibers (they are always sensory). 
 
 There is a third kind, 
 ^. which connects nerve cell 
 
 with nerve cell in the 
 brain; they are known 
 as association fibers. 
 
 Nerve action. If an 
 afferent nerve be irritated 
 at its outer endings in 
 
 afM^ssner the Cells of the tisSUCS, 
 
 an impulse will travel to 
 the brain or spinal cord. 
 If it goes to the brain, 
 consciousness of the im- 
 pulse will be apparent; 
 if. it goes only as far as 
 the cord, there will be 
 
 FIG. 169. Sens6ry nerve ending in skin, i Pnn o P i nil onp?q nf 
 
 showing tactile corpuscle of Meissner. 
 
 the fact. In either case 
 
 there may be a motor response to the sensory impulse in 
 the form of a reflex* act. Impulses may originate in the 
 brain and pass to different cells in the body, causing 
 them to act. This occurs when one consciously makes a 
 muscular movement. Transmitting nerve impulses is the 
 whole duty of nerve fibers. The endings of the nerves are 
 so abundant in the skin just beneath the epithelium that 
 the point of a needle cannot enter without causing pain. 
 They are more numerous there than in any other part of 
 the body. Afferent nerves are not so abundant in the muscles 
 
 -Nerve 
 
The Nervous System 
 
 293 
 
 and internal organs as in the skin, so that a cut gives most 
 pain as it enters the skin and may be continued into deeper 
 parts with only slight pain. Efferent nerves begin in the 
 nerve cells of the spinal cord and end in the muscles and glands 
 of the body. Efferent nerves and efferent impulses have three 
 functions, controlling motion, secretion, and growth. 
 Because of this multiplicity of function, it is desirable to 
 call them efferent 
 nerves rather 
 than to use the old 
 term " motor." 
 The nerve im- 
 pulse, as demon- 
 strated in the frog, 
 travels about 100 
 feet per second. 
 This is the speed 
 
 of an PYnross train 
 1 
 
 going 70 miles an 
 
 hour. It is prob- 
 
 able that in warm-blooded animals, such as man, the rate is 
 
 even faster. 
 
 General sensations. The cells of the body are constantly 
 sending impulses to the central nervous system, signifying 
 their needs. These impulses give rise to feelings to which 
 the mind assigns no definite location in the body; hence 
 they are called general sensations. Such feelings as hunger, 
 thirst, fatigue, and sleepiness belong to this class. They are 
 as well understood by a baby or any young animal as by a 
 man, and unlike the special sensations, the meaning of general 
 sensations does not have to be learned, as the memory of 
 them owing to inherited habit seems to reside in the nervous 
 system. General sensations are sometimes called instincts. 
 
 Special sensations. When something outside of the body 
 acts upon the nerves, it produces a feeling or sensation by 
 
 FlG ' 170. Pacinian body. These touch end- 
 
 ings give the sense of pressure. 
 
 dermis. 
 
 Located in the 
 
294 Healthful Living 
 
 which the mind forms ideas of the surroundings of the body. 
 The meanings of these feelings must be learned when first 
 perceived, and they are mostly learned in childhood. The 
 special senses, taste, sight, smell, pain, temperature, and 
 muscular sense, are of such importance that all will be in- 
 cluded in a separate chapter. 
 
 Injury to nerves. If motor or efferent nerves going to 
 a muscle are cut, there is paralysis of the muscle, so that 
 there can be no voluntary or reflex action in the part. If an 
 efferent nerve going to a gland is cut, the function of the 
 gland will be almost suspended. Even if food is taken into 
 the mouth and the sensory nerves carry the news to the 
 brain, the efferent nerve being cut, no impulse can return and 
 the secretion will be very slight. When the motor nerve 
 to a part is cut, the cells will be almost too inactive to absorb 
 and carry on growth and repair ; hence unless continually 
 under the influence of motor nerves the cells dwindle away. 
 When the cells are much used, the impulses sent cause them 
 to take in more nourishment and to grow in size. Thus a 
 muscle increases in size and strength when much used. You 
 learned that during the action of a. muscle, the vasomotor 
 nerves going to the arteries in the muscle cause what change ? 
 Will this also aid in growth ? When a nerve is cut, the ends, 
 if placed together, will grow again, the parts supplied by it 
 being paralyzed in the meantime. 
 
 Nerves may become inflamed, and the disease is called 
 neuritis, just as inflammation of the tonsils is called ton- 
 sillitis, or of the stomach is called gastritis. Neuritis of the 
 sciatic nerve is called sciatica; it is a very painful disease. 
 One of the many dangers of using alcohol is that it may 
 produce neuritis. Either slow, steady drinking or occasional 
 "sprees" may cause it. The disease gives no warning before 
 it comes, and may remain a long while. Rheumatism or 
 malaria may also cause it, but alcohol produces the disease 
 as often as all other causes combined. 
 
The Nervous System 
 
 295 
 
 General arrangement of the nervous system. The 
 
 brain and the spinal cord make the central nervous system. 
 The nerves coming from the brain are the cranial * nerves 
 (Fig. 171). There are twelve pairs. The nerves from the 
 
 { face -Sensory 
 Face-Motor 
 
 Taste 
 
 Spinal Cord 
 /st Spfna/ Nerve 
 -2d Spina/ Nerve 
 
 \ 
 
 \^ L,iver 
 *-...-* 
 
 FIG. 171. Diagram of the twelve cranial nerves. These are twelve 
 pairs of cranial nerves which arise from the brain and go out through the 
 holes in the lower wall of the skull. (How many pairs of spinal nerves 
 are there?) The cranial nerves are numbered according to the location 
 of their roots, from above downward. 
 
 cord are called the spinal nerves. There are thirty-one 
 pairs of spinal nerves. These nerves running from the central 
 nervous system make up the peripheral system. There are 
 other nerves connecting mainly the involuntary structures 
 with the cord. This connection is made by nerves that end 
 in masses of nerve cells (ganglia) lying along each side of 
 
296 Healthful Living 
 
 the front of the vertebral column. These make up the 
 autonomic* system. 
 
 The spinal cord. Structure. The various white nerve 
 fibers, both efferent and afferent, of the entire body unite 
 and form forty-three pairs of larger nerves ; twelve of these 
 pairs, called cranial nerves, go to the brain, and thirty-one 
 pairs, called spinal nerves, go to the spinal cord. Each one of 
 the sixty-two spinal nerves enters the spinal cord by two 
 roots, one posterior and one anterior. It is significant that 
 all the efferent and afferent fibers of a spinal nerve separate 
 from each other. The efferent fibers enter by the anterior 
 root, and the afferent nerves by the posterior root (Fig. 173) . 
 The afferent fibers do not really enter the cord but end in 
 a ganglion on the posterior root, and the ganglion sends 
 dendrites into the cord by the posterior root. The spinal 
 cord extends from the foramen magnum " or great open- 
 ing," in the occipital bone down to about the second lumbar 
 vertebra. What parts of a vertebra form the canal for the 
 cord? Is the canal made of bone throughout its length? 
 How are the vertebrae united with one another ? 
 
 The spinal cord is about the size of the little finger. It 
 is only about two thirds as large as its tube, so that it is not 
 likely to be injured by bending the spinal column. The 
 rest of the space in the canal is taken up by a lymphlike 
 liquid, and three membranes called meninges which form 
 a triple covering for the cord. These membranes extend 
 into the skull and cover the brain. An inflammation of 
 them constitutes a very serious disease called cerebro-spinal 
 meningitis. 
 
 A cross section of the spinal cord shows that it is a double 
 organ (Fig. 172), the halves being united by a narrow por- 
 tion ; it shows also that the central part of the cord is of 
 gray matter in the outline of a butterfly, and surrounded 
 by a thick layer of white fibers. The gray portion is made 
 up of nerve cells that give off fibers, many of which go to the 
 
The Nervous System 
 
 297 
 
 spinal nerves and some go upward in the outer white portion 
 of the cord. The white tract also contains motor threads 
 
 Posterior /foot 
 
 White Matte 
 
 GrayMettt 
 
 Anterior Root V 
 
 FIG. 172. Cross section of the spinal cord. Afferent impulses come in 
 over the posterior root ; efferent impulses go out over the anterior root. 
 
 that bring impulses from the brain to the cells in the graj r 
 matter. 
 
 Function. The brain sends impulses to the cells in the 
 spinal cord, and they, being aroused, in turn send motor 
 impulses to the muscles. When a person wills to move his 
 hand, an impulse goes to the spinal cells, and they in turn 
 send impulses that cause a contraction of the muscles in 
 the arm. The brain sends about ten impulses per second 
 to keep the muscle in action. Thus, before it can relax, 
 another impulse reaches it. Each muscle has its own set 
 of spinal cells in the cord which act as a relay station be- 
 tween the muscle and the brain. The cells of the spinal 
 cord have another very important duty; they largely con- 
 trol reflex action. At times it would take too long for the 
 brain to act, so the body needs a quicker governing power 
 to supply its needs or protect it from injury. If the finger 
 touches a hot object, the brain becomes conscious of the 
 
298 Healthful Living 
 
 burn and of the movement of the finger at about the same 
 time. There are also many acts that are performed so often 
 that the spinal cord acquires the habit of sending back the 
 appropriate impulses. Thus muscles and other organs may 
 be controlled and the brain be relieved to attend to other 
 duties. 
 
 The same motor cells of the spinal cord that produce mo- 
 tion in a part, also exercise an oversight that controls the 
 growth and nutrition of the cells in that part. The impulses 
 from the spinal cells furnish a constant stimulus to growth 
 and repair. 
 
 A crumb entering the larynx brings on a fit of coughing. 
 A dash of cold water makes us hold our breath. A pinch 
 of pepper causes us to sneeze. If the foot of a sleeping person 
 is tickled, he will kick; if a fly settles on his face, he will 
 brush it off. Sometimes a person in an unconscious con- 
 dition will drink a cup of water if it is placed to the lips. 
 
 If the back is broken, reflex actions persist although all 
 sensation and volition concerning the parts below the injury 
 are suspended. The leg will kick when the foot is tickled, 
 etc. A surgeon tickled the foot of a man whose spinal cord 
 was injured, and the feet kept up a vigorous kicking. He 
 asked the man if he felt it ; he said, " No, but you see that 
 my feet do." On carefully testing the sensibility of such 
 a man, a line can be traced girdling the body, dividing the 
 sensitive from the insensitive part. The brain also may 
 act seemingly in a reflex manner as in cases of somnambulism, 
 or sleep-walking. 
 
 When one is learning new movements, such as walking, 
 skating, writing, riding a bicycle, each movement is a vol- 
 untary one as far as the will is capable of watching so many 
 muscles, The movements are, therefore, slow and awkward. 
 After the movements have been made many hundreds of 
 times, they become easy and graceful, and also less vol- 
 untary. This is accomplished by the nerve impulse select- 
 
The Nervous System 299 
 
 ing the pathway that gives the right response. At first 
 many pathways are used and tried. When the pathway is 
 found that gives the result sought and there is pleasure in 
 the reaction, then the movement is learned and it becomes 
 easy and graceful. 
 
 We must not think of reflexes as being only related to 
 muscles and movement. They may have a character that 
 prevents or suppresses movement. A dash of cold water 
 on the chest will inhibit respiration. A sudden emotional 
 shock may be so terrifying as to prevent muscular contraction 
 and one will stand still in the face of great danger. Reflex 
 activity of glands is often not related to movement. The 
 secretion of tears, caused by a cinder in the eye, is reflex. 
 The impulse is carried to the lachrymal (tear) gland by the 
 secretory nerves. These nerves are efferent but not motor. 
 
 Education of reflex action consists mainly of the forma- 
 tion of habits. The impression on the nervous system from 
 the training is made chiefly on the spinal centers. When the 
 muscles of the hand are educated, it is really the spinal cells 
 that are educated. During youth, one is always acquiring 
 good habits or bad habits. The habit of an upright, easy 
 walk, the habit of dropping into a stooping posture, of putting 
 the hands in the pockets, of making wry faces, of mumbling 
 and stammering, or of talking distinctly and without hesi- 
 tation, may be acquired, and will probably remain through 
 life, for impressions made on the nervous system in youth 
 are lasting. The habit of eating temperately of pure food, 
 the habit of stuffing, of awaking the nerves with stimulat- 
 ing condiments, of using alcoholic stimulants, of using 
 tobacco, are easily acquired, but are lost with difficulty. 
 Good habits are good friends ; bad habits are enemies. It 
 often requires years of constant effort to root out bad habits, 
 but it is very easy to keep them out in the first place; Yet 
 if the wish and will for a better habit is really strong, one 
 need never despair, for on account of the large size and great 
 
300 Healthful Living 
 
 activity of the brain, and its preponderance over the lower 
 reflex centers, man is distinguished above all other animals 
 by his power of forming new habits. If our ideals are high, 
 we can go on forming better habits, and intrusting them to 
 the keeping of the nerve centers, and thus make step after 
 step toward our ideal. If our ideals are not high, or if they 
 are mere theories and never affect our acts, we may never 
 improve, but may even degenerate: 
 
 The autonomic system. The nerves coming off from the 
 spinal cord and going to the muscles are called the spinal 
 or skeletal nerves. Those coming from the brain are called 
 the cranial nerves. There are other nerves which innervate 
 the organs of the body and these come from both spinal cord 
 and brain. At one time they were called " sympathetic* 
 nerves " but now the name autonomic is given to these 
 nerves. They supply the viscera, blood vessels, glands, and 
 hair. It is seen, therefore, that skeletal muscles receive 
 their stimulation from the central nervous system and the 
 involuntary muscles of the body receive their stimulation 
 from the autonomic system. Now the motor nerves supply- 
 ing the skeletal muscles come from cells which lie in the 
 ventral part of the spinal cord ; the glands and smooth 
 muscle of the viscera receive their innervation from nerves 
 which come from ganglions which lie outside the spinal cord. 
 The difference between the two systems in type is shown in 
 Figure 173. The neurons running to the visceral organs 
 usually have their cell bodies grouped in ganglia and this 
 arrangement gives rise in certain places to a mass of nerve tis- 
 sue which receives the name plexus. Hence, we have the solar 
 plexus, the cardiac plexus, the splenic plexus, etc. (Fig. 175). 
 The ganglia and plexuses of the autonomic system are con- 
 nected with the brain and spinal cord by neurons whose cell 
 bodies lie within the spinal cord. It is to be noticed, therefore, 
 that there are two sets of neurons of this system ; one from 
 the cord and brain to the ganglion sometimes called the pre- 
 
The Nervous System 
 
 301 
 
 ganglionic neuron ; and one from the ganglion to the viscera 
 and gland and sometimes called the postganglionic neuron. 
 This arrangement is shown in Figure 174. This figure should 
 be studied with reference to the arrangement of the three 
 divisions of this, system. The name autonomic has been 
 suggested by Langley and indicates that the structures 
 
 Post-Gangfionfc Fiber 
 
 Post-Ganqtionic 
 
 Gang/ion of 
 'ufonom/c System 
 
 FIG. 173. The preganglionic fibers of the autonomic system leave 
 the motor root and run to the ganglion. 
 
 supplied by these nerves are not under voluntary control. 
 In addition only a part could be classed under the old head- 
 ing of sympathetic. So it is that there are given three 
 divisions, the thoracico-lumbar * (sympathetic), the cranial, 
 and the sacral.* 
 
 Thoracic-Lumbar Division. The second division has 
 the largest distribution. It sends fibers to the eyes and 
 causes dilatation of the pupils. To this division belong the 
 accelerator nerves that go to the heart (Figs. 174, 175). 
 They cause it to beat faster. They also carry impulses to 
 
Artery of Salivary G/and 
 
 y - Surface Artery 
 Sweat G/and 
 
 rtery 
 
 FIG. 174. Diagram of the important parts of the autonomic nervous 
 system, (a) preganglionic fibers ; (6) postganglionic fibers ; (c) plexus ; 
 (d) ganglia situated outside the cord; spinal cord and medulla and the 
 parts to which the fibers go. 
 
 302 
 
The Nervous System 
 
 303 
 
 the muscle of the arteries and so make possible vaso-con- 
 striction. The stimulation of the fibers which go to the 
 muscles of the hair causes the hair to stand on end. It is 
 also known that the stimulation of these nerve fibers occurs 
 
 Spinal Ganglia 
 
 Spinal Ganglia 
 
 Spinal Ganglia 
 
 Cardiac Plexus 
 
 Solar Plexus 
 
 -ffypotjastric Plexus 
 
 FIG. 175. Diagram of trunk showing one of the two rows of autonomic 
 ganglia near the spinal column and the plexuses. 
 
 under conditions which call forth emotional reactions. For 
 example, when one is afraid, the hair stands on end; de- 
 pressing conditions cause the flow of tears; the heart rate 
 is increased at times of emotional disturbance. 
 
304 Healthful Living 
 
 Cranial Division. The cranial autonomic serves to 
 protect the body and to conserve its strength. The main 
 part of the cranial division is the vagus nerve which runs 
 to the heart and all the abdominal organs (Fig. 174). The 
 cranial autonomic goes also to the salivary gland and causes 
 it to secrete more saliva. It slows the heart and causes 
 the contraction of the pupil. An analysis of these functions 
 will show that this division serves to conserve the body. 
 By slowing the heart, the cardiac muscle is given a chance to 
 rest ; by contracting the pupil the retina is protected ; by 
 stimulating the flow of saliva, gastric, and other digestive 
 juices and by causing the contraction of the smooth muscle 
 of the viscera, all the processes of digestion are accelerated 
 and energy is produced with the least expenditure of energy. 
 This makes for conservation of strength and reserve force. 
 
 Sacral Division. The sacral division provides for the 
 contraction of the smooth muscles concerned in emptying 
 the organs which hold the waste of the body. These nerves 
 control the action, therefore, of the colon, rectum, and 
 bladder. This section may be thought of as rendering serv- 
 ice to the body by keeping the waste removed and so it is 
 of importance in body health and conservation. 
 
 Antagonism between the Sympathetic Division and the 
 Cranial and Sacral. This very complex mechanism for 
 controlling the involuntary action of the bodily processes 
 has a very interesting action, in that there is antagonism be- 
 tween the ends and central part of the system. Cannon 
 says, " When the mid-part meets either end part in any 
 viscus their effects are antagonistic." For example, the 
 cranial fibers contract the pupil, the sympathetic fibers 
 dilate it. The cranial fibers (the vagus) slow the heart, the 
 sympathetic (the accelerator nerves) accelerate the heart. 
 These opposed effects are indicated in Figure 174 in which 
 + means contraction, acceleration, and means relaxation, 
 retardation. 
 
The Nervous System 305 
 
 Functions of the Autonomic System. It is important to 
 understand the working of this mechanism and to see how 
 this knowledge can guide us in shaping our lives so that we 
 may act in harmony with the mechanism of our bodies and 
 not against it. It is always of value to act in accordance 
 with the laws of health as well as the laws of the nation. 
 From an understanding of this autonomic system, we ap- 
 preciate why it is desirable to be happy and cheerful at meal- 
 times in particular. Emotional disturbance near meal times 
 interferes with digestion because the sympathetic fibers 
 carry the impulses concerned in rage, anger, fear, .or pain," 
 and these impulses will interfere with the impulses sent by 
 the cranial division, supplying the digestive juices. So it 
 is that all the processes of the body are assisted and accel- 
 erated by conditions that are cheerful. Happiness is a 
 desirable stimulant and will work marvelously to keep the 
 body well. One should not give expression to feeling of 
 crossness, sullenness, pouting, anger, etc. Beyond the fact 
 that they injure the body, of more importance is the fact 
 that they make other people unhappy. 
 
 Afferent Nerves of the Autonomic System. The afferent 
 impulses through these nerves are slow and faint, seldom 
 reaching beyond the spinal ganglia to the brain. Thus the 
 circulation of the blood and the digestion of the food usually 
 go on without our consciousness, but a very strong irrita- 
 tion may give rise to consciousness and pain in the abdominal 
 organs, as in colic or in vomiting. Sensory impulses, signify- 
 ing the needs of the cells and the necessity for movement in 
 the arteries and intestines, are being continually sent to the 
 spinal ganglia (Fig. 175). Only very strong impulses caused 
 by disturbances that may injure the body, reach the brain, 
 and cause pain. 
 
 Efferent Nerves of the Autonomic System. The efferent 
 nerves carry impulses which cause the epithelial cells of 
 the glands to make their secretions, and the muscles of the 
 
306 Healthful Living 
 
 arteries and intestines to contract. They do this as a re- 
 flex response to the impulses going to the spinal ganglia 
 from the sensory nerves of the system. At a flash of bright 
 light the eye winks and the pupil contracts. The sweat 
 glands secrete under the influence of warmth. It was 
 formerly believed by physiologists that the " sympathetic " 
 ganglia themselves sent the reflex motor impulses, but it is 
 now believed that these come from the spinal ganglia. The 
 "sympathetic" ganglia are supposed to reenforce the current 
 and aid in the nutrition of the nerves that pass through 
 them. 
 
 The brain. The spinal cord can act only in response 
 to impulses at the moment they are received. The brain 
 can originate impulses which are not in direct response to a 
 stimulus from the outer world. Its acts are apparently 
 spontaneous, but they probably result from the combination 
 of impulses previously received, which memory has enabled 
 it to store up and retain. The brain not only causes action 
 and directs the cord in giving order to voluntary movements, 
 but it can restrain excessive action in the spinal cord. Self- 
 control comes largely through the power possessed by the 
 brain of restraining the spinal cells from sending out reflex 
 impulses when strong and sudden impulses are received 
 from the outer world. This is called the inhibitory power. 
 If a door slams, a person whose brain is not exerting good 
 control jumps suddenly. 
 
 Coverings of the Brain. What facts did you learn about 
 the skull, showing that it is well constructed for protecting 
 the brain ? The brain is covered by three membranes ; the 
 outer tough one lines the skull and the spinal canal. The 
 next is thinner. There is a lymphlike fluid, called the 
 cerebro-spinal fluid, within this membrane, so that the brain 
 is surrounded by a kind of water bed. The third, and inner- 
 most, covering is hardly a membrane, for it is merely a thin 
 network of fine blood vessels and connective tissue. It dips 
 
The Nervous System 307 
 
 down into every depression and fold of the outer layer of 
 gray cells of the brain. This layer of gray matter is called 
 the cortex. The folds in it are called convolutions (See 
 Plate VII). Numerous folds signify great intelligence. 
 
 Weight. The weight of the brain of the average man is 
 forty-nine ounces (a little over three pounds), and of the 
 average woman is forty-four ounces. The woman's brain 
 is as large in proportion to the size of her body as a man's 
 brain. Man's brain is surpassed in weight by the brains of 
 only two animals. A whale, measuring seventy feet long, 
 has a brain weighing only five pounds, and an elephant's 
 enormous body is controlled by a brain of about eight pounds. 
 Birds' brains are heavier in proportion to their bodies than 
 the brain of any other animal. The brain grows very 
 rapidly till the fifth year, then very slowly; the growth 
 after twenty is very slight. Cromwell's brain is said to have 
 weighed almost eighty ounces. Other great men have had 
 large brains, but some great minds have inhabited very 
 small brains. Quality is as important as quantity. The 
 brains of idiots are usually very small. 
 
 The Cerebrum. The chief parts of the brain are the 
 cerebrum, the cerebellum, and the medulla oblongata. The 
 cerebrum, or great brain, divided by a cleft into two parts, 
 is highest in the skull, and covers all the other parts 
 (Plate VI) . It is composed of cells which lie in the cortex 
 and fibers which pass from the cells to and from the spinal 
 cord and cranial nerves (Figs. 176, 177). Sense-perception, 
 consciousness, reason, and the will are located in the cerebrum. 
 The cerebrum, as all other organs, is dependent upon circula- 
 tion, respiration, digestion, and excretion. If the heart sud- 
 denly weakens its action very much, or if the vasomotor 
 nerves allow the arteries to lose tone suddenly and increase 
 their capacity for blood, the person faints, from a weakening of 
 the circulation through the brain. Recovery is brought about 
 by placing the head on a lower level than the body, so that 
 
3 o8 
 
 Healthful Living 
 
 the blood may run to the brain with less exertion on the part 
 of the heart. A violent blow on the head may make one 
 insensible at once. By breathing chloroform, ether, or 
 
 carbon dioxide, by taking mor- 
 phine, the quality of the blood 
 may be so altered as to bring 
 sleep. In order that the brain 
 may act, it must be constantly 
 aroused by impulses from the 
 outer world. Man loses con- 
 sciousness as soon as his cerebral 
 hemispheres cease to act ; but 
 his heart and lungs keep at work. 
 It is curious that touching the 
 cerebrum, or stimulating it with 
 electricity, when it has been ex- 
 posed by accident, arouses no 
 sensation, although this organ is 
 believed to be the seat of con- 
 sciousness. This fact is of great 
 interest, for it shows that im- 
 pressions coming from the sense 
 organs alone enter into conscious- 
 . ,. ness. Fresh air, good food, and 
 
 FIG. 176. Microscopic dia- . ' 
 
 gram of the cells in the cortex pure blood are essential for the 
 of the cerebrum, a external best functioning of the cerebrum. 
 
 layer showing association cell, ' . 
 
 axone, and dendrites ; 6, py- Effect of Removing Cerebrum. 
 
 ramidai cell which sends off _ A f ter destruction of the cere- 
 
 axone to enter the layer of m 
 
 meduiiated fibers c. The den- brum, an animal may continue to 
 
 drites of the pyramidal cells R tf f d b h d j t can run 
 pass into layer a. J 
 
 about, and swallow food placed 
 
 within its mouth. It will be disturbed by a loud sound, 
 such as the blowing of a horn. It might avoid a bright 
 flame if placed in its path, but would go stupidly against 
 other objects; but it is idiotic, for all acts of intelligence 
 
TJte Nervous System 
 
 39 
 
 cease. Its time is spent in sleep or mechanical wandering. 
 A frog deprived of its cerebrum retains some more extensive 
 powers than a warm-blooded animal. It starts to hopping 
 when touched, 
 avoids obstacles 
 in its path, re- 
 covers its usual 
 position when 
 placed on its back, 
 swims when 
 thrown into water, 
 and when placed 
 on a board that is 
 slowly tilted, it 
 will preserve its 
 balance by climb- 
 ing to the top. 
 These actions are 
 reflex but of a 
 higher order than 
 a simple reflex act. 
 The reason the 
 frog continues 
 hopping after be- 
 ing touched is that 
 each hop, owing 
 to the contact of 
 the skin with the 
 ground, excites 
 
 FIG. 177. Diagram of the motor area and the 
 
 another hoD the motor tract in the brain. Find centers for leg, arm, 
 
 animal never be- 
 gins to move of its 
 own accord. 
 
 Centers in the 
 Cerebrum (Figs. 
 
 face. Notice that most of the motor fibers from 
 one hemisphere cross to the opposite side of the 
 spiral cord ; and if one half of the brain is injured, 
 the opposite half of the body loses motion and 
 sensation (paralysis). Trace nerve impulse from 
 cell 1 in cortex at c to muscle at 6 (1-3). Trace 
 reflex impulse from skin at a to muscle at b (4, 5, 
 
 6, 3). 
 
3 io 
 
 Healthful Living 
 
 178, 179, 180). When the part of the cerebrum that lies 
 behind the ear is destroyed, a loss of the memory for the 
 meaning of words may result. One can speak, but his words 
 follow each other without sense or meaning. The sense of 
 hearing is supposed to be located in the same region. The 
 sense of sight is located in the rear part of the cerebrum. If 
 
 FIG. 178. Localized areas of the cortex. 
 
 the rear part of the left hemisphere is destroyed, a man is 
 unable to see anything to the right of his nose when his eyes 
 are directed straight forward. The sense of smell lies at the 
 base of the cerebrum toward the front (Figs. 179, 181). 
 
 A wounded soldier was brought to the surgeons with 
 part of his skull torn away. The surgeons used an electric 
 current to test whether the nerves were paralyzed. They 
 were astonished to find that whenever the electric current 
 was applied to the wounded part of the head, muscular 
 
The Nervous System 
 
 movements were excited. It was soon determined that by 
 stimulating electrically a certain area of the cerebral 
 cortex movements on 
 the opposite side of the 
 body can be excited. 
 This area, called the 
 motor area (Fig. 178), 
 lies under the parietal 
 bone, and extends 
 from the top of the 
 brain to the level of 
 the ear. By experi- 
 ments On monkeys FlG - 179 - ~ View of one cerebral hemi- 
 1 . , sphere from between the hemispheres showing 
 
 and dOgS, and by mo tor and sensory centers. 
 
 studying cases of acci- 
 dents to the skull in human beings, this area has been sub- 
 divided. Stimulation of the lowest part causes movements 
 
 of the face ; of the 
 middle part, the 
 arm ; and of the 
 upper part, the leg, 
 the movement al- 
 ways being on the 
 side opposite to the 
 stimulation (Fig. 
 180). When the 
 lowest part of the 
 area on the left side 
 in right-handed per- 
 sons is injured, the 
 
 Fio. 180. Motor and sensory centers. Most power of speech is 
 centers occur in both hemispheres, and if one is , m , 
 
 injured, the other will continue to work. lost. Ihe Compre- 
 
 hension of words 
 
 and the ability to write, read, and hear language is not lost. 
 With left-handed persons, this center is on the right side. 
 
312 Healthful Living 
 
 The Cerebellum. The cerebellum, or small brain, is at 
 the base of the skull behind. If a pigeon has its cerebellum 
 removed, it is restless and has wide-open eyes; it flutters, 
 but cannot fly. If the cerebrum is removed, leaving the 
 cerebellum, it is stupid, but flies if thrown into the air. By 
 placing the hand at the back of the skull between the occiput 
 and the neck, you will cover the part occupied by the cere- 
 bellum. Coordination of the muscles is carried out by the 
 cerebellum. You will to walk through activity of the cere- 
 brum ; the control of the muscles while walking is the function 
 of the cerebellum. 
 
 Function of the Cerebellum. The removal of the whole 
 of the cerebellum from an animal does not produce death 
 so long as the medulla is not injured, but the animal becomes 
 weak and unsteady in its movements. If the cerebrum re- 
 mains, the mental faculties are retained. Disease of the 
 cerebellum in man produces dizziness and leads to a stagger- 
 ing, reeling gate. Hence it is believed that the function of 
 the cerebellum is to aid the cerebrum in the control of the 
 muscles. It brings about proper coordination of the muscu- 
 lar movements, so that in such movements as standing, 
 walking, talking, the different muscles may each act at the 
 right moment and with due force. The spinal cord also 
 coordinates movements. For instance, if a frog is decapi- 
 tated and left quiet for an hour or two, so that the spinal 
 cord may recover from the shock due to the injury, it may 
 be made to execute seemingly purposeful movements. If a 
 drop of acid be placed on the flank of such a frog, the leg 
 will be drawn up and the acid wiped off with the toes. But 
 such coordinated movements are not accompanied by con- 
 sciousness. 
 
 The Medulla Oblongata. This, the most important of 
 the cerebral ganglia, may be looked upon as the part of the 
 spinal cord within the skull. It is just within the foramen 
 magnum, and is intermediate in position and function be- 
 
The Nervous System 
 
 313 
 
 0/fBCtory 
 
 O/ factory 
 ~ Bulb 
 
 tween the brain and spinal cord. The spinal cord acts re- 
 
 flexly; the brain acts consciously. Conscious actions are 
 
 those which are influenced by mental images or ideas. The 
 
 medulla contains reflex centers and the centers of automatic 
 
 action. This kind of action should not be confused with 
 
 acquired reflexes, such as walking, to which the term "auto- 
 
 matic" is sometimes applied. Automatic centers are those 
 
 which are con- 
 
 trolled by the 
 
 condition of the 
 
 blood. They are 
 
 stimulated by 
 
 an increase of 
 
 carbon dioxide 
 
 in the blood. 
 
 The chief of 
 
 these centers is 
 
 the respiratory 
 
 center of the 
 
 medulla If it ^ IQ> ^^' ^ e ^ ac t r y nerve. The main nerve 
 
 . . . * ends in the form of a bulb on the floor of the skull. 
 
 IS injured, death The fibers branch from this bulb like the roots from 
 
 ensues bv Sllffo- an omon an d spread out on the walls of the nasal 
 
 k chamber. 
 
 cation. The 
 
 cerebellum or even the cerebrum may be injured or removed 
 from the lower animals without causing death, but the 
 smallest injury to the respiratory center kills the animal 
 immediately. In cases of hanging, it is injury to this center 
 that causes death. Another very important center in the 
 medulla, controlled by automatic action, that is, by the 
 varying condition of the blood, is the center for vasomotor 
 nerves, which regulate the size of the blood vessels. It was 
 previously learned that the vasomotor fibers belong to the 
 autonomic system. There are also important reflex centers 
 in the medulla, viz., the centers for the secretion of saliva. 
 for swallowing, for vomiting. 
 
314 
 
 Healthful Living 
 
 Mucous Membrane 
 
 How Automatic Centers Work. As the blood becomes 
 deficient in oxygen and charged with carbon dioxide, the 
 respiratory center is irritated and sends out impulses which 
 cause deeper breathing. This improves the condition of the 
 blood, and the respiration is quieter until the blood again 
 loses oxygen; then stronger impulses are sent, and so on, 
 
 thus regulating 
 the condition of 
 the blood auto- 
 matically. The 
 size of the blood 
 vessels is regu- 
 lated in the same 
 way by the vas- 
 omotor center in 
 the medulla, in- 
 crease of carbon 
 dioxide causing 
 contraction of the 
 
 FIG. 182. Diagram of a salivary gland. Showing 
 
 automatic control (after Landois and Sterling). SUriace Vessels, 
 
 decrease of it 
 
 causing relaxation. Automatic acts take place in series. 
 Reflex acts, such, for example, as walking, can take place 
 in series also, but the first stimulus in reflex acts comes from 
 without the body ; in automatic acts from the blood. Fig- 
 ure 182 shows how a center controlling the secretion in a 
 gland may receive impulses from the mucous membrane, 
 from the brain, and then impulses are sent to the blood 
 vessel to dilate and supply more blood and to the gland to 
 begin to secrete. 
 
 GLOSSARY 
 
 Afferent (nerves). Conducting inward toward the cord and 
 
 brain. 
 Association. Refers to nerve fibers that are concerned in purposely 
 
 connecting different nerves or brain areas. 
 
The Nervous System 315 
 
 Autonomic. Entirely independent and self-supporting in itself. 
 
 Cranial. Relating to the cranium or the organ within the cranium, 
 the brain. 
 
 Dendrites. The tree-like branches of a nerve cell. The den- 
 drite receives the nerve impulse from the axon. 
 
 Efferent (nerves). Conducting away from the cord and brain. 
 All efferent impulses are not motor and so efferent and afferent 
 are more desirable terms than motor and sensory. 
 
 Medullated. Covered with a soft fatty substance ; that is, covered 
 with a medulla. 
 
 Neuron. A nerve cell with its dendrites and axon and hence the 
 structural unit of the nervous system. 
 
 Peripherally. Away from the center. 
 
 Reflex. An act that goes on without the direction of the brain. 
 It occurs before the individual is hardly conscious of the act. 
 He may be conscious afterwards that he has acted but he has 
 given no direction in the process. 
 
 Sacral. Relating to the sacrum, near the sacrum or coming from 
 the sacrum. 
 
 Sympathetic. A part of the nervous system of the body that 
 originally was supposed to be concerned in acts that were of 
 a sympathetic character. The name now is autonomic be- 
 cause it is known that the chief characteristic of this sys- 
 tem is the ability to carry on its activities without direc- 
 tion or help. Also its activities involve more than was 
 connoted by the term " sympathetic." 
 
 Thoracico-lumbar. A compound word referring to the thoracic 
 and lumbar regions of the vertebral column. 
 
CHAPTER XVI 
 HYGIENE OF THE NERVOUS SYSTEM 
 
 I. Connection between Body and Mind. 
 II. The Effect of Activity on the Nervous System. 
 
 III. The Effect of Sleep. 
 
 IV. The Effect of Fatigue. 
 V. The Effect of Alcohol. 
 
 VI. Improper Functioning of the Nervous System. 
 Drugs and insanity 
 Communicable disease and insanity 
 Habits of mind and insanity 
 VII. Ten Golden Rules of Health for School Children. 
 
 Connection between body and mind. The body and the 
 mind are very closely related, are interdependent and 
 are a unit. We have learned that muscle and nerve are 
 interdependent. So it is with mind and body. Only rarely 
 do you find a fine mind in a poor body; and in such 
 an instance, the individual has lost largely the quality of 
 bodily vigor which enables him to perpetuate his greatness. 
 This unity of body and mind, this balance of physical and 
 mental powers is essential for the welfare of the race. 
 Men and women should not only preserve, but if possible im- 
 prove the quality of life they have, so that the race will be en- 
 riched. There are many familiar examples of the connection 
 between mind and body. Most men who have been great 
 workers with their minds have also been zealous in using 
 their muscles. There is a flexibility of mind and disposition 
 that results from a mixed occupation which is in great con- 
 trast with the machine-like dullness and narrowness of mind 
 
 316 
 
Hygiene of the Nervous System 317 
 
 produced by a monotonous, one-sided occupation, whether 
 mental or physical. Gladstone chopped down trees; Li 
 Hung Chang when eighty years old walked three miles daily 
 around the courtyards of his palace ; Napoleon rode horse- 
 back; William Cullen Bryant, upon rising in the morning, 
 swung a chair around his head, took wand exercise with a 
 cane, and practiced other gymnastics. He walked five 
 miles to his work. 
 
 The connection between body and mind is readily illus- 
 trated. The pulse rate is affected by every emotion. Shame 
 causes the blood vessels of the face to dilate. Painful emo- 
 tions excite the activity of the lachrymal* or tear glands. 
 Joy increases ease of movement. If an excited or angry 
 man who is walking to and fro sits down, his excitement 
 decreases. A starving man and one suffering from fever 
 have hallucinations.* The Romans had the proverb " a 
 sound mind in a sound body." The care of the body for 
 the mental effect as well as for the sake of the body itself, 
 is only gradually regaining the high place it held among the 
 Greeks and the Romans, a place which it lost during the 
 Dark Ages. " Hysteria * and nervous exhaustion are the 
 fruits not of over-work, but of lack of varied and interesting 
 employment. The absurd opinion that hard work is menial 
 and low, leads to most pernicious consequences. The girl 
 who, turning from brain work to manual labor, can cook, 
 scrub, wash, and garden, invites the bloom of health to her 
 cheeks ; while the fine do-nothing lady loses her good looks, 
 suffers from the blues, and is a nuisance to her friends and 
 a misery to herself." 
 
 The effect of activity on the nervous system. If the 
 cells of any tissues are not active in the performance of the 
 work for which they are intended, they become weakened. 
 It is the same with the nervous system. Fresh and new 
 sensations are necessary for the health of the brain; those 
 mental faculties that are used become strong. Unused 
 
318 Healthful Living 
 
 muscles become flabby and ill-nourished because the circu- 
 lation in them is weakened ; the circulation in inactive 
 nervous tissue also becomes less active. Mental activity 
 strengthens the nervous system and the body in general. 
 If one protects his sensory nerves by too warm clothing and 
 never lets the cold air strike them, they become weakened 
 and unreliable and allow the blood vessels to lose tone. They 
 are likely to do strange things with the circulation, causing 
 colds and disease. If, because of pulpy or soft food, the 
 nerves of the alimentary canal are not stimulated mechan- 
 ically, peristalsis is weakened and the intestine becomes 
 clogged. The loss of tone in the circulation and the sluggish 
 peristalsis, with the troubles that follow, can often be improved 
 by taking a cold bath every morning. The stimulus to the 
 sensory nerves spreads reflexly to the vasomotor nerves and 
 to the autonomic fibers of the intestine ; these are " toned 
 up " and restore activity to the involuntary muscles. 
 
 The effect of sleep. The cells of the body with all their in- 
 dustry are not tireless, and at intervals require rest (Figs. 183, 
 184, 185). During sleep the heart beats more slowly, respira- 
 tion is less rapid, the muscles in general are relaxed, the gland 
 cells diminish their secretions, and digestion is slow. The 
 production of heat is lessened and the body must be pro- 
 tected from cold. Yet consciousness is the only function 
 entirely in abeyance. The sound of a passing vehicle 
 quickens the pulse of the sleeper without awaking him; if 
 he is touched, he moves. Sleep is deepest during the second 
 hour, and it then takes a much louder sound to awaken him 
 than during later hours. Sleep becomes gradually lighter 
 until awakening occurs. When consciousness is partly 
 present, the condition is called dreaming.* In somnambu- 
 lism,* the sleeper may talk or walk as he dreams. 
 
 There are different explanations given for the cause of 
 sleep. Some believe that it results from the accumulation 
 of waste products in the body ; it is also held that it is due 
 
Hygiene of the Nervous System 
 
 V%fehK)-j; : <-/. 
 X 
 
 *Sr 
 
 / .x-v -.%.- '.3 ..:*%:.%. -- , i .: 
 
 
 FIG. 183. Showing various types of nerve cells (bodies) from the 
 spinal cord. These cells are rested. 
 
320 
 
 Healthful Living 
 
 to lack of circulation in the brain. Now the process is not 
 fully known, but it is perfectly clear that individuals re- 
 quire sleep (Figs. 184, 185). If sleep is interfered with, the 
 body is injured. There should not be in this as in so many 
 other things the disposition to make yourself and your friends 
 uncomfortable by the insistence at all times on a certain 
 number of hours. There are occasions when it may be very 
 
 FIG. 184. Tired nerve cell bodies from the spinal cord. These cells 
 show the nucleus to one side, the chromatin * decreased in amount and at 
 the wall of the cell. Compare with the cells shown in Figs. 183 and 185. 
 
 desirable to take less sleep than customary, and we should 
 be able to go with less sleep for a time in the accomplish- 
 ment of important work. The number of hours of sleep for 
 children of different ages is given on page 326. 
 
 For a sound nervous system, nothing is so indispensable 
 as plenty of sound sleep. It is necessary for growth and re- 
 pair of the cells (Fig. 185). Infants sleep almost all the 
 time ; children of four or five, nearly half the time ; those of 
 
Hygiene of the Nervous System 
 
 321 
 
 ten or twelve, ten hours; most college students require 
 eight hours, and this amount is required by most adults. 
 The morning should bring a feeling of vigor. If we wake 
 tired and discouraged, there is something amiss. It may 
 be that there was over-exertion the day before and the sleep 
 has not been long enough, or that we have been up too late 
 or have eaten improper things. If the last is the case, there 
 is apt to be a bad taste in the mouth on awakening. By 
 
 FIG. 185. Brain cells at rest, in action, exhausted (Crile). 
 
 going to bed at the same hour every night, the habit is formed 
 of dropping off promptly and soundly to sleep. A cheerful 
 state of mind with resolute avoidance of worry promotes 
 sound sleep at night. The sleeping room should be cool, 
 but it is not necessary that water freeze " in the pitcher." 
 It should be well ventilated, the window being left open 
 even in moderately cold weather in the northern states, and 
 in very cold weather in the Gulf states, unless the room is 
 loosely built. 
 
322 Healthful Living 
 
 The effect of fatigue. Waste products produced in one 
 part of the body are carried by the circulating blood, before 
 they can be removed, to all parts of the body. Fatigue in 
 one part causes a loss of efficiency in other parts. It is well 
 known that the boy who plays football for two hours in the 
 afternoon is unable to study in a satisfactory way in the 
 evening. Such fatigue is natural and healthful. After 
 the period of rest, the body is recreated and the taking in 
 of food by the body cells, called assimilation,* results in the 
 organization of the food into living tissue. It is known 
 that mental activity does not greatly increase waste sub- 
 stances, but that does not mean that one cannot overwork 
 mentally. The feeling of fatigue which comes from tired 
 eye muscles and tired joints should indicate the need for a 
 change of activity. This change will be satisfied best by 
 physical exercise of the game or sport type. 
 
 The effect of alcohol. As alcohol acts on many organs 
 through its action on the nervous system, it would naturally 
 be supposed that the nervous matter itself would be injured, 
 and such is the case (Figs. 229, 230). In fact, it is upon the 
 delicate nervous system that its most destructive effects are 
 wrought. One of the first effects of alcohol is flushing of 
 the face and a feeling of warmth on the surface of the body. 
 This is due to the quickened action of the heart and the dila- 
 tion of the small blood vessels from the effects of alcohol 
 on the nerve centers controlling these organs. The mind is 
 at first more active, because the little vessels of the brain are 
 dilated and blood is sent more freely to that part. A little 
 later the alcohol begins to disturb the reflex and coordinating 
 powers of the nervous system, and ordinary muscular move- 
 ments are performed imperfectly and with difficulty. The 
 nerve centers seem to be attacked and paralyzed progressively 
 by alcohol, beginning with the highest and proceeding toward 
 the lowest. The will power and judgment first become 
 paralyzed, and only the emotional and impulsive instincts 
 
Hygiene of the Nervous System 323 
 
 of human nature are left ; these, being no longer under con- 
 trol of reason and judgment, are likely to cause the individual 
 to act in an irrational manner. In the last stages, conscious- 
 ness and volition are lost, and only that part of the nervous 
 system in the medulla which governs circulation and res- 
 piration remains active. In other words, the man is " dead 
 drunk. " A large quantity of alcohol may produce death 
 by paralyzing even these nerve centers, thus stopping all 
 organic functions. This overact ion and irregular action of 
 
 Alcohol and Precision as Shown by Marksmanship 
 
 1st Tests. No Alcohol -Average No. of Hits 23 
 
 2nd Tests. Alcohol Taken Average No. of Hits 3 
 3rd Tests. No Alcohol -Average No. of Hits 26 
 
 FIG. 186. Fewer hits were made on the alcohol days, but the soldiers 
 thought they were shooting better. 
 
 ; 
 
 the nerves, when repeatedly occurring, has the effect finally 
 of deforming or destroying the nerve tissue. 
 
 It is well known that skill in a movement or act is de- 
 veloped by a training of the nervous system. Now alcohol 
 lessens skill and precision in fine work. There is no work 
 or play that man performs that cannot be performed better 
 without alcohol. In tests of target shooting, the advantage 
 of abstinence and the disadvantage of using alcohol were 
 clearly shown by experiment. In this test (Fig. 186), 
 during the first series no alcohol was used ; in the second 
 series two thirds of a wine glass of brandy was taken 20 to 
 30 minutes before shooting and an equal amount of alcohol 
 in punch on the evening before. No one who aims to 
 achieve a place in the world and in the respect of friends 
 
324 Healthful Living 
 
 can afford to use alcohol in any form. Its effect on the 
 nervous system is especially disastrous. 
 
 Alcohol lessens skill and precision in fine work where 
 head, hand, eye, muscles, and nerves must work together 
 for deftness and accuracy. 
 
 It is common knowledge that a musician, who is indulging 
 in alcohol, will make more mistakes in playing. The 
 fine adjustments and coordinations are then no longer 
 possible. Those who look forward to having power over 
 and control of the body should guard against the danger 
 of alcohol. 
 
 Improper functioning of the nervous system. Nearly 
 everyone has known of some one who has gone insane. Such 
 disease of the mind was little understood in the past, and 
 insane persons were thought to possess evil spirits. In- 
 sanity * is usually thought of as coming quickly, and the most 
 fantastic causes are given for its occurrence. Now the im- 
 portant thing for us to remember is that insanity usually 
 develops slowly and its causes are well known. Insanity 
 is much more frequent than is generally supposed, and in the 
 state of New York about one in every 200 of the adult popu- 
 lation is in an insane hospital. In ten years insanity in this 
 state has increased 104 per cent. 
 
 Drugs and insanity. Opium,* morphine,* and cocaine * 
 cause a large proportion of the insane in every state. Alco- 
 holic insanity may be caused by the regular use of alcohol 
 even in moderate quantities which do not produce intoxica- 
 tion. It is stated that 30 per cent of the men and 10 per 
 cent of "the women in the state hospitals are suffering from 
 conditions due to alcohol. In states where there is pro- 
 hibition, the amount of insanity is much less. This is 
 scientific information and has the support and belief of the 
 highest medical authorities. These poisons, alcohol, opium, 
 morphine, and cocaine make up the principal parts of many 
 patent medicines. This is another reason for forbidding 
 
Hygiene of the Nervous System 325 
 
 their use because they often weaken the mental powers 
 and produce insanity. 
 
 Communicable diseases and insanity. Mental disturb- 
 ance of a serious nature may follow certain diseases. The 
 poison from typhoid fever,* diphtheria,* and tuberculosis* 
 may so injure the nervous system that complete recovery 
 does not occur. Many cases of insanity are produced by a 
 specific communicable disease that is contracted through 
 immoral acts. Those who are weak enough not to con- 
 trol themselves may look forward to the possibility of 
 " softening of the brain/' or, as it is called by doctors, general 
 paralysis. 
 
 Habits of mind and insanity. Habits of mind are im- 
 portant factors in producing mental disturbance. The 
 state of mind that is most favorable for the health of 
 the nervous system is the one in which the individual is 
 satisfied with life and is not nursing the misfortunes that 
 happen to befall him. It is dangerous to brood and pout 
 over slights, disappointments, and injuries. Such unwhole- 
 some mental reaction if persisted in may tend toward 
 insanity. Some people think that their disposition is fixed 
 like the color of the eye, but it is not so. A cheerful, 
 optimistic, friendly, and happy disposition may be trained 
 and achieved. 
 
 Hard work alone rarely causes a breakdown of the nervous 
 system, unless there is associated with it loss of sleep and 
 worry. Henry Ward Beecher once said, "It is not hard 
 work that kills men ; it is worry." v 
 
 TEN GOLDEN RULES OF HEALTH FOR SCHOOL CHILDREN 1 
 
 I. Sleep get as many hours in bed each night as this 
 table indicates for your age. Keep windows in bedroom 
 well open. 
 
 1 Proposed by Dr. Thomas D. Wood, Columbia University. 
 
326 
 
 Healthful Living 
 
 HOURS OF SLEEP FOR DIFFERENT AGES 
 
 AGE 
 
 HOURS OP SLEEP 
 
 TIME IN BED 
 
 5-6 
 
 13 
 
 6 P.M. to 7 A.M. 
 
 6-8 
 
 12 
 
 7 P.M. to 7 A.M. 
 
 8-10 
 
 lit 
 
 7 : 30 P.M. to 7 A.M. 
 
 10-12 
 
 11 
 
 8 P.M. to 7 A.M. 
 
 12-14 
 
 10| 
 
 8:30 P.M. to 7 A.M. 
 
 14-16 
 
 10 
 
 9 P.M. to 7 A.M. 
 
 16-18 
 
 . 9 
 
 9 : 30 P.M. to 7 A.M. 
 
 II. Eat slowly never between meals. Chew food thor- 
 oughly. Drink water with meals but never when there is 
 food in the mouth. Drink water several times during the day. 
 
 III. Brush your teeth at least once a day. Rinse mouth 
 out well with water after each meal. 
 
 IV. Be sure your bowels move at least once each day. 
 
 V. Take a warm, cleansing bath with soap once or twice 
 a week. Take a tepid or cool sponge (or shower) bath each 
 morning before breakfast and rub -body to a glow with a 
 rough towel. 
 
 VI. Keep clean body, clothes, and mind. Wash your 
 hands always before eating. 
 
 VII. Play hard and fair. Be loyal to your team mates 
 and generous to your opponents. 
 
 VIII. Study for keeps. 
 
 IX. Do all you can to help keep your school and your 
 home clean and attractive. 
 
 X. Be cheerful and do your best to make the world a better 
 place to live in. 
 
 APPLIED PHYSIOLOGY 
 Exercise I 
 
 1. Why is it best to change from very absorbing work to work 
 of less interest a while before retiring? 
 
 2. Why is the power of habit a blessing ? A danger ? 
 
Hygiene of the Nervous System 327 
 
 3. How does travel often cure a sick person when all else fails? 
 
 4. Why should we never study immediately after eating? 
 
 5. Is it better for children to play or to take exercise? 
 
 6. What causes the peristaltic action of the stomach? 
 
 7. Is one more likely to sleep soundly who does his brain work 
 in the forenoon and muscular work in the afternoon than if he 
 reverses the order? 
 
 8. How do fatigue and sleep affect the nervous system? 
 
 Exercise II 
 
 9. How does anger cause indigestion ? 
 
 10. Does perfectly comfortable clothing from head to foot con- 
 tribute to one's ease in company? 
 
 11. Does uncomfortable clothing make one self-conscious? 
 
 12. Is it as important to have the shoes and the clothing per- 
 fectly comfortable when going out as when staying at home ? 
 
 13. Would you get more rest by sleeping for four hours undis- 
 turbed, or by sleeping eight hours but being awakened every half 
 hour by some noise, and going immediately to sleep again ? 
 
 14. When one sits with the leg under the body, why is it that 
 the compression causes a tingling sensation or paralyzed feeling 
 in the foot ? 
 
 15. Do the girl, who frets over washing the dishes, working 
 with an unwilling mind, and the boy who, while he is sawing wood, 
 is wishing to go to a baseball game, do their work with more or 
 less fatigue than if they worked cheerfully and willingly? Why? 
 
 16. What are the causes of improper functioning of the nervous 
 system ? 
 
 Exercise III 
 
 17. How is a sneeze a protective act? 
 
 18. Why may a dyspeptic digest a large Thanksgiving or Christ- 
 mas dinner when he often has trouble with an ordinary dinner ? 
 
 19. Why is it more difficult for an adult to learn to speak a 
 language than for a child? Why do adults find drawing and 
 languages more difficult to acquire than history and mathematics ? 
 
 20. In what two ways may opening a window when a student is 
 becoming dull and drowsy at his books enable him to wake up and 
 study with ease ? 
 
 21. Muscles may be classed as minor, such as those of the eye, 
 voice, hand; and major, such as those of upper arm, leg, trunk. 
 
328 
 
 Healthful Living 
 
 Why is the use of the minor muscles exhausting to the nerves, while 
 the use of the major muscles strengthens the nerves? 
 
 22. Why do you throw cold water upon a fainting person? 
 
 23. Why may cold feet cause sleeplessness ? 
 
 24. Why does constant moderate drinking undermine the health 
 more than occasional intoxication ? 
 
 25. The vasomotor nerves control the size of the blood vessels. 
 Which nerve centers control these nerves? Why does a draught 
 blowing on the back of the neck often cause a cold? 
 
 LABORATORY EXERCISES 
 
 Reaction Time. The nervous system is arranged to protect the 
 body from injurious conditions affecting it through its environment. 
 This protection is shown when the eyes are closed to shut out the 
 light that is too bright, when the hand is thrown in front of the 
 face to ward off a thrown missile, and when the hand is withdrawn 
 
 FIG. 187. The inductorium. (The set screw holding the trunnion 
 block tube against the side rod is not shown.) 
 
 on coming in contact with a hot stove. These are a few of the many 
 instances of the protective reactions of the nervous system. Now 
 the quickness of this reaction varies in different people, and the 
 length of the time from the moment the outside stimulus is received 
 and the body reacts is shorter or longer depending on the activity 
 of the nervous system. This time is called the reaction time and 
 is capable of measurement. 
 
Hygiene of the Nervous System 
 
 329 
 
 Experiment 1. To study the reaction time of the nervous system. 
 
 Material. Inductorium, signal magnet, copper wires, elec- 
 tric batteries, kymograph, and keys. (Figs. 187, 188, 189, 190.) 
 
 FIG. 188. Electrodes. About two fifths the actual size, 
 electrodes are attached to the inductorium. 
 
 The 
 
 Method and observation. Arrange a signal in the primary cir- 
 cuit of the induction apparatus with the two keys. Place the 
 kymograph with smoked paper in contact with the recording point 
 of the signal magnet. Let the subject 
 hold the electrodes of the inductorium 
 on the tip of the tongue with one hand 
 and with the other hold down the one 
 key. The experimenter will then spin 
 the drum and close the other key. 
 This closing of the key will make the 
 circuit and hence will produce an 
 electric shock. When the subject feels 
 the shock on the tongue, he breaks the 
 circuit by opening his key. This clos- 
 ing and opening of the circuit produces a movement of the signal 
 which is recorded on the kymograph, and so there is a graphic 
 record of the time the stimulus was received and the moment the 
 response was given. This interval is the Reaction Time. 
 
 FIG. '189. The simple 
 key ; about three eighths the 
 actual size. 
 
 FIG. 190. The signal magnet. 
 
33 Healthful Living 
 
 GLOSSARY 
 
 Assimilation. The last act of the process of nutrition. It follows 
 digestion and absorption. After the food elements are di- 
 gested and absorbed, the transformation of them into an in- 
 tegral part of the cells of the body is assimilation. 
 
 Chromatin. The coloring matter of the nucleus. The chromatin 
 contains the essential elements of the cell and is important in 
 reproduction of the cell. 
 
 Cocaine. A white, bitter, crystalline alkaloid with the formula 
 (Ci 7 H2iNO 4 ). It produces loss of feeling when injected into 
 the skin. 
 
 Diphtheria. A disease caused by the Bacillus diphtheria. The 
 organisms grow on the mucous membrane of the throat, 
 larynx, and nose and produce toxins which circulating in the 
 blood cause the injury to the heart and nerves and the re- 
 sulting symptoms. 
 
 Dream. A succession of mental images, usually incoherent and 
 confused, that come in sleep. 
 
 Fever. A general disturbance of the body characterized by an 
 increase in body temperature. Often preceded by a chill and 
 followed by quickened pulse and respiration. The communi- 
 cable diseases all produce some fever. 
 
 Hallucination. An apparent perception with no corresponding 
 external object. Sights seen and sounds heard without there 
 being any object or cause of sound, illustrate the condition. 
 
 Hysteria. A nervous state in which the individual rapidly 
 changes from laughing to crying accompanied with a choking 
 sensation in the throat. 
 
 Insanity. A condition of the mind brought about by diseased 
 processes in the brain or nervous system. The individual 
 lacks the ability to think and act in the way which is con- 
 sidered by most people to be sane. 
 
 Lachrymal. The gland which secretes tears ; the duct which 
 carries them over the eye ball; the name of the secretion 
 itself. 
 
 Morphine. A bitter, crystalline, narcotic alkaloid with the 
 formula (CnHigNOs). It is a derivative of opium. 
 
 Opium. A product of the unripe capsules of the poppy. Chemi- 
 cally it is a mixture of different alkaloids, chief among them 
 being codein and morphine. 
 
Hygiene of the Nervous System 331 
 
 Somnambulism. Performing the act of walking and other pur- 
 posive acts during sleep. 
 
 Tuberculosis. A disease caused by the Bacillus tuberculosis. 
 This organism may attack almost any structure in the body. 
 There may arise tuberculosis of the lungs, of the liver, of the 
 brain, of the kidneys, of the intestines, and other organs. 
 
 Typhoid fever. A disease caused by the Bacillus typhosus. This 
 organism attains entrance to the body through water, milk, 
 or food that has been contaminated by one sick with the 
 disease. 
 
CHAPTER XVII 
 SENSATION AND THE SPECIAL SENSES 
 
 I. Classification of the Senses. 
 
 II. The Sense of Taste. 
 
 III. The Sense of Smell. 
 
 IV. The Sense of Sight. 
 
 The external parts of the eye 
 The interior structure of the eye 
 The .act of accommodation 
 
 Regulation by the iris of the amount of light admitted 
 Defects of vision 
 Care of the eyes 
 V. The Sense of Hearing. 
 
 Structure and function of the ear 
 Care of the ear 
 VI. The Sense of Touch. 
 Temperature 
 Pain 
 Pressure 
 
 VII. The Muscular Sense. 
 VIII. General Sensations. 
 Hunger 
 Thirst 
 
 Classification of the senses. In animal life the develop- 
 ment of the nervous system has produced certain groups 
 of nerve cells for the purpose of carrying on particular tasks. 
 The eye is a nerve structure which has undergone a re- 
 markable development so that man may be more familiar 
 with his environment. The endings of a nerve in the tongue 
 make possible the distinction between sweet and sour, 
 palatable and distasteful food. Sensory nerves in the skin 
 
 332 
 
Sensation and the Special Senses 
 
 333 
 
 inform us regarding the objects in the world around us. 
 The touch sensation is compound. It conveys qualities of 
 pressure, warmth, cold, and pain. The temperature sen- 
 sation is always projected externally to objects; the pain 
 sense goes inward and is felt as a sensation * within the body. 
 The sensory nerves in the skin have special endings and 
 each nerve has special work to do. There are cold and 
 warm, pressure and pain nerves and, when stimulated, each 
 carries its own kind of sensation. Pressure nerve endings 
 transmit a sense of pressure ; cold endings carry a sensation 
 of cold, etc. Sensory nerves also have endings in the muscles 
 and these nerves on contraction of the muscle tell the brain 
 how intense the contraction is and where the part has moved. 
 Some of these fibers end in the cerebellum and this sense 
 at work helps to maintain the balance of the body. It is 
 called our muscle sense. In addition, there are certain 
 common sensations, such as hunger and thirst. We feel 
 them as existing within the body. 
 
 
 1. Taste 
 
 
 
 2. Smell 
 
 
 Special 
 
 3. Sight 
 
 
 Senses 
 
 4. Hearing 
 
 f Temperature 
 
 
 5. Touch 
 
 ] Pain 
 
 
 6. Muscle sense 
 
 I Pressure 
 
 General 
 
 1. Hunger 
 
 
 Senses 
 
 2. Thirst 
 
 
 Sensations 
 
 The sense of taste. It was mentioned that the tip of 
 the tongue has a very keen sense of touch. The tongue is 
 a very muscular organ, and when we are eating, it helps to 
 keep the food between the teeth ; it also does the chief part 
 of the work in the beginning of the process of swallowing. 
 But perhaps its most important function is to afford a home 
 for the nerves of taste. These nerves consist of a branch 
 of the fifth pair of nerves, which are distributed over the 
 
334 Healthful Living 
 
 front part of the tongue, and the ninth pair, which go to 
 the back part of the tongue (Fig. 171). Although we often 
 speak of food as being palatable, the sense of taste in the 
 palate is very feebly developed. 
 
 What we call flavors affect us through the sense of smell. 
 If the nostrils be held closed, a piece of onion placed on 
 the tongue does not have the " taste " of onion at first, 
 nor at all, unless particles are wafted up and pass through 
 the pharynx into the nose. An apple is, under the same 
 conditions, as tasteless as an Irish potato. If the nose is 
 held shut, ground coffee placed upon the tongue loses its 
 flavor and is as tasteless as sand, if the tongue is wiped dry. 
 The way to make these tests is to obtain the articles and 
 have them given to you for tasting, without knowing which 
 you are getting ; then find whether or not you can tell the 
 difference. 
 
 Substances, in order to be tasted, must first be dissolved 
 on the tongue. The tip of the tongue is most sensitive to 
 sweets and salines, the back part to bitters, and the sides to 
 acids. 
 
 The sense of smell. In quiet breathing most of the air 
 passes along the lower parts of the nasal passages, just above 
 the hard palate. Fibers of the olfactory nerve end mostly 
 in the higher part of the nasal passages. When we wish to 
 test an odor, we sniff, that is, we take a sudden inspiration 
 by jerking the diaphragm down. A volume of air larger than 
 usual rushes in, more of it passes over the parts of the walls 
 in which the olfactory fibers are located. It is necessary 
 that the substance producing the odor be in a very finely 
 divided condition, probably gaseous. 
 
 Smell has its source in the beginnings of the respiratory 
 passages, just as taste is at the gateway of the alimentary 
 canal ; and just as taste by its influence on the salivary and 
 gastric glands, greatly influences digestion, so the sense of 
 smell greatly influences the respiratory acts. The breath- 
 
Sensation and the Special Senses 335 
 
 ing of a pleasant odor increases the depth of the breathing. 
 Pleasant odors, as of flowers and of fresh country air and of 
 the forest, contribute to our health and well-being. Why 
 do foods lose flavor when one has a very bad cold in the 
 nose? 
 
 The sense of sight. The eye brings to the brain from the 
 external world pictures of form, color, and movement. With- 
 out the eye, color and movement could not be ascertained 
 and form would be only partially sensed. How would form 
 be known in part? This marvelous structure, the eye, is 
 set into a hollow, formed by the bones of the skull. The 
 camera in structure and function is similar to the eye. 
 Familiarize yourself with the parts of a camera and identify 
 these with parts in the eye. 
 
 The external parts of the eye. The eye is a globular organ, 
 set in a bony socket. It is controlled in its movements by 
 muscles, protected from dust and dirt by the lids and lashes, 
 and on its exposed surface, the conjunctiva, it is moistened 
 by a secretion from the lachrymal gland. These structures 
 form the external parts of the eye and will be described be- 
 fore the internal structure of the eye proper will be given. 
 
 The Oculo-motor Muscles (Fig. 191). The eyeball is 
 capable of being turned in all directions by means of six 
 slender muscles which begin in the back part of the orbit. 
 Four of them are straight. The one above turns the eye 
 upward, the one below turns it downward, the one toward the 
 nose turns it inward, and the one toward the temple turns 
 it outward. The other two are oblique. The superior 
 oblique muscle passes forward through a loop which serves 
 as a pulley near the inner upper front part of the orbit 
 (Fig. 191). It rotates the eye in one direction, and its antag- 
 onist, the inferior oblique muscle, rotates it in the opposite 
 direction. " Cross eyes " are caused by too great con- 
 traction of the internal straight muscles, and " wall eyes " 
 are caused by too great contraction of the external straight 
 
336 
 
 Healthful Living 
 
 xe-c,u s 
 
 FIG. 191. A, the muscles of the right eye- 
 ball (viewed from above). B, the muscles of 
 the left eyeball (viewed from the outer side). 
 
 muscles. The defects may be remedied by a skillful surgeon, 
 who cuts the proper muscle with a suitable instrument, and 
 
 permits it in healing 
 become attached 
 another point 
 
 f 1 1 i i 
 
 Optic 
 
 to 
 to 
 farther back. 
 
 A person is blind 
 while the eyes are 
 moving. Watch 
 while some one in 
 front of the class 
 tries to move the 
 eyes gradually and 
 uniformly across the 
 field of vision. Do 
 
 the eyes move by jumps or steadily? The motions of 
 
 the lids and eyeball give the expression of the eye. 
 
 The eyeball itself has hardly more expression than a glass 
 
 eye. 
 
 We judge the distance of objects by the lines of conver- 
 
 gence of the two eyes. This conver- 
 
 gence is accomplished by the harmoni- 
 
 ous action of the eye muscles. A 
 
 boy with one eye has difficulty in 
 
 knowing when a ball thrown will 
 
 reach his hand. When we look at a 
 
 solid object, each eye sees a little 
 
 more of the object on its side than 
 
 does the other. Thus two eyes make 
 
 it easier to distinguish bodies. By 
 
 taking two photographs of a solid 
 
 scene from slightly different points 
 
 and arranging them so that the eyes of light from A and B are 
 
 look at the pictures separately &' 
 
 FlG192< _ Diagram of 
 
 a stereoscope. Two photo- 
 
 the same time the idea of solidity appear to come from c. 
 
Sensation and the Special Senses 337 
 
 is given. The stereoscope * (Fig. 192) secures this arrange- 
 ment. 
 
 The Lids. The upper and lower lids protect the eye. 
 They are supplied with muscles and can be moved very 
 quickly. The upper lid has greater movement. From the 
 edges of the lids grow hairs, called lashes. The lashes pro- 
 tect the eye from dust and are very sensitive to all pressure. 
 The under surface of the lids is covered by conjunctiva in 
 which are located glands which produce an oily secretion. 
 This secretion prevents the rapid drying of the watery se- 
 cretion that comes from the lachrymal gland. 
 
 The Lachrymal Gland. The lachrymal gland is some- 
 times called the tear gland. It is located above the eye- 
 ball, between the ball and the 
 bony arch on the side toward 
 the temple. It is flattened and 
 oval in shape, about three quar- 
 ters of an inch in length. About J)uct ' 
 ten small ducts lead from it and 
 open on the under side of the 
 upper lid. The secretion that it 
 
 furnishes to the conjunctiva is partially dissected to show lach- 
 
 formed continually. The tears J^ *^ d and lachrymal 
 pass across the eye and flow into 
 
 two small ducts, the openings into which can be seen on the 
 borders of each eyelid near the inner angle of the eye. They 
 open into a canal which leads into the nasal passage (Fig. 193). 
 When one weeps, why is it necessary to blow the nose fre- 
 quently? At the ordinary rate of supply, the tears do not 
 overflow, as there is a waxy secretion along the edge of the 
 eyelid that turns them toward the ducts. When have you 
 noticed a waxy secretion in the corner of the eye? 
 
 The Conjunctiva. The eye is apparently set in a slit 
 in the skin of the face, but this is not really the case. The 
 skin of the eyelids turns inward over their edges and becomes 
 
338 Healthful Living 
 
 a thin, transparent, and exceedingly sensitive mucous mem- 
 brane, called the conjunctiva. It is, like other mucous 
 membranes, composed of epithelial cells. The conjunctiva 
 goes back under the lid and over half the eyeball itself to 
 the other lid, so that the eye is really behind the skin. When 
 the eye is directed very much to one side, the conjunctiva 
 is sometimes seen lying in wrinkles. The veins which we 
 think we see in the white wall of the eyeball when the eye 
 is " blood-shot " are usually in the conjunctiva, which is 
 so transparent that we do not easily see it unless its vessels 
 are swollen. Trachoma,* sometimes known as " sore eyes," 
 is a disease of the conjunctiva. This serious infection of 
 the conjunctiva is not infrequent among school children. 
 This disease is very serious and affects the sight if not 
 properly cared for. It is transmitted from child to child 
 by use of the common roller towel, by borrowed handker- 
 chiefs and other personal property that comes in contact 
 with the face of the child. Always use your own individual 
 towel and never lend or borrow a handkerchief. 
 
 The Health Department of the City of New York has 
 issued the following bulletin for parents : 
 
 DEPARTMENT OF HEALTH 
 
 THE CITY OF NEW YORK 
 Instructions to Parents Regarding Trachoma 
 
 Trachoma is a contagious disease of the eyelids. If left un- 
 treated it is very dangerous to the eyesight. 
 
 It first attacks the inner surface of the eyelids, later it spreads 
 to the eyeball itself and causes loss of sight. 
 
 In the beginning the eyes may be red and watery and they 
 may, from time to time, contain matter, but often for a long time 
 there are no symptoms that the person notices, and the disease is 
 frequently first discovered by the doctor. It is very difficult to 
 cure trachoma, and it is the more difficult the longer the disease 
 has lasted. For this reason trachoma should be detected as early 
 
Sensation and the Special Senses 
 
 339 
 
 as possible. It is contagious when secretion, that is to say " matter," 
 is present. This secretion is conveyed from the eye of the person 
 affected to the eye of the healthy person and thus sets up the 
 disease. The secretion is for the most part conveyed by means of 
 towels, washrags, and handkerchiefs, and persons with trachoma 
 should always be careful that their towels, washrags, and hand- 
 kerchiefs are used by themselves only. It is not on the street 
 that trachoma is transmitted from one person to another, but 
 generally in the home, and it is, therefore, in the home that the 
 greatest precautions should be taken. 
 
 Children who have trachoma are not allowed to attend school 
 unless they are regularly treated. 
 
 If your child has sore eyes, take it to your doctor or to a Dis- 
 pensary * at once. 
 
 The interior structure of the eye. The eyeball (Fig. 194) 
 is a globular chamber filled with transparent fluids. This 
 
 Irrs 
 Ci/iary Musc/e 
 
 Retina 
 
 Choroief 
 
 'c/erot/c Coat 
 
 FIG. 194. The anatomy of the eye. 
 
 chamber is divided into two compartments (Fig. 194) by a 
 semi-solid crystalline * substance called the lens,* and a mus- 
 cular diaphragm (Fig. 195), the iris. The wall of the eye 
 is made of three layers of tissue, called coats of the eye. 
 
 Coats of the Eyeball. The sclerotic * coat is the tough 
 white outer coat of connective tissue. It preserves the 
 
34 Healthful Living 
 
 shape of the eye and serves for the attachment of the muscles. 
 This coat is pierced in only one place, and that is for the 
 entrance of the optic nerve. It is continuous over the front 
 of the eye, where it becomes transparent, and is called the 
 cornea. You can see the cornea bulging out in the front, 
 of a classmate's eye if you look at it from the side. The 
 middle coat, the coat just within the sclerotic, is the choroid.* 
 It consists of pigment cells and blood vessels. The choroid 
 coat does not cover completely the whole ball. It is not over 
 the cornea, but at the beginning of the cornea the choroid 
 turns toward the center of the eye and forms the iris. The 
 iris has an opening called the pupil,* and this opening be- 
 cause of small muscles can change in size. The iris changes 
 the opening of the pupil to allow just sufficient light to 
 properly stimulate the optic nerves. When the light is 
 dim, the pupil is opened wider and in bright light it is con- 
 tracted to a small opening. The point where the choroid 
 leaves the sclerotic coat to form the iris marks the attach- 
 ment of the lens to the choroid. These two structures, iris 
 and lens, divide the 'chamber of the eye into two compart- 
 ments. In the anterior chamber is the aqueous humor;* 
 in the posterior, is the vitreous humor.* 
 
 The retina * is the third or innermost layer of the wall. It 
 lines the chamber. It is composed of the end filaments of 
 the optic nerve. These are a hundred thousand or more in 
 number. The ray of light on coming into the eye stimulates 
 these sensory endings of the optic nerve. To receive this 
 stimulus of the light ray is 'the function of the retina, and to 
 transmit it to the brain, is the function of the optic nerves 
 (Fig. 197). 
 
 The Aqueous Humor. The aqueous humor is a trans- 
 parent liquid. This liquid gives firmness to the front part 
 of the eye. It allows rays of light to pass through without 
 deflection. 
 
 The Vitreous Humor. The posterior compartment is 
 
Sensation and the Special Senses 341 
 
 the larger and main part of the chamber. The vitreous 
 humor that fills this space is a perfectly clear liquid. 
 
 The Crystalline Lens. The lens (Fig. 194) is a perfectly 
 clear transparent structure, jelly-like in consistency. It is 
 suspended by ligaments from the choroid at the place where 
 the iris begins. The ligament is called the suspensory 
 ligament. 
 
 Take a lens that is rounded outward (convex) * on both 
 sides, such as a hand magnifier, or even a strong lens from 
 an old person's spectacles. Hold this up on the side of a 
 room opposite to a window and catch the image* of the 
 window on a white cardboard held back of the lens. This 
 illustrates how the image of an external object is formed by 
 the crystalline lens upon the retina. If some one stands 
 up in the window, does he appear in the upper or lower part 
 of the image? If he moves to the right, in what direction 
 does his image move? The reversals are explained by the 
 crossing of the rays of light as they pass through the lens. 
 If two lenses of different thickness be used, it will be 
 found that the cardboard must be moved close to catch 
 the image from the thicker lens. The lens serves to 
 refract the rays of light and focus them to produce a clear 
 image. 
 
 The Yellow Spot. The yellow spot is a minute area of 
 the retina that is in direct line from the pupil. The nerve 
 endings in this area are of such a character that vision is 
 clearest at this point (Fig. 194). 
 
 The Blind Spot. Light falling on the optic nerve itself 
 does not give the sensation of light, but gives it only when 
 falling upon the ends of the nerve fibers. Where the optic 
 nerve enters the eyeball, there are none of these endings, 
 and the light that falls there does not enable us to see any- 
 thing. In the following experiment shut the right eye, and 
 be careful not to let the eye. waver : * Read this line slowly. 
 Can you see the star all the time? If not, change the dis- 
 
342 
 
 Healthful Living 
 
 tance to the book and read the line again. In the human 
 eye the optic nerve enters not in the center, but at a point 
 toward the other eye. The optic nerve along its course is 
 not sensible to light, but if it is cut, it gives the sensation of 
 a flashlight. This shows that the nerve, when stimulated, 
 responds by transmitting the kind of impulse that is as- 
 sociated with its function. 
 
 The act of accommodation. Hold a pencil or finger in 
 line with some object, as a picture on the wall. When 
 looking at the finger, the picture is blurred and vice versa. 
 
 FIG. 195. Diagram to illustrate accommodation. 
 
 When looking up from a book that we are reading, to a 
 distant object, we do not realize that any change in the 
 eye is necessary; but the lens changes in shape, becoming 
 more flattened for the more distant object, and becoming 
 thicker again when a near object is looked at, thus always 
 bringing the rays to a focus upon the retina at whatever 
 distance the object may be (Fig. 195). But the power fails 
 at a point called the near point, about four inches from the 
 eye for most persons, and the image becomes indistinct. 
 The change in shape of the lens is called accommodation ; 
 it is brought about by means of the muscular fibers around 
 the lens. Straining of the muscles is required for looking 
 at very near objects. 
 
Sensation and the Special Senses 343 
 
 Regulation by the iris of the amount of light admitted. 
 Look toward a bright window or the sky and note by means 
 of a hand mirror the size of the pupil. Turn at right angles 
 to the light, still looking in the mirror, and note the size 
 of the pupils. What have you 
 noticed about the eyes of a cat at 
 night or in the darkened room? 
 How do your own eyes feel when 
 going from the dark into a lighted 
 room ? Can you see as well when 
 you first go from a brightly * he retina at B - 
 lighted room into a dimly lighted 
 
 one, as after being in the dim 
 
 light for a short time ? The iris 
 contains circular muscle fibers, A 
 which reduce the size of the 
 
 i t i- . . /! i i Myopic, or nearsighted eve, in 
 
 pupil, and radiating fibers, which which ,!,,, raya of light ( A , A) 
 enlarge the pupil. The arrange- '-- '.- l ^ " 
 
 ment Of pigment Sometimes fol- the retina at B, the rays diverging 
 
 lows the line of the fibers. Have 
 you ever noticed lines in the iris ? 
 Did you ever whirl a stick 
 with a glowing coal on its end ? 
 What was noticed? Can you 
 notice anything similar if vou 
 
 * Hypermetropic, or farsighted, eye, 
 
 shake the hand up and down in which parallel rays of light (A, A) 
 
 . , , , ,, ., ,, r, -re are focused behind the retina at D, 
 
 quickly before the face ? If yOU producing a blurred image at B. 
 
 gaze for a moment at a bright FIG. 196. 
 
 light, then quickly close the eyes, 
 
 what is noticed after the eyes are closed? These effects, 
 called after-images,* are produced by the action of light 
 upon the pigment of the retina, an effect which persists 
 for a fraction of a second after the light is removed. 
 
 Defects of vision (Figs. 196, 198). In near-sighted eyes the 
 eye is too long from front to back, and the rays come to a 
 
344 
 
 Healthful Living 
 
 focus before reaching the retina. Among savage nations, 
 where no books are used, almost every one has good sight, 
 and nearsightedness is hardly known. Nearsightedness may 
 be inherited or may begin with children at school. Some 
 children seem to have a natural wish to get their eyes close 
 to the book or writing. This is 
 very undesirable for nearsighted 
 persons. The head should be held 
 erect in reading, to prevent blood 
 congesting in the eyes, and to pre- 
 vent round shoulders and flat chest. 
 The proper distance for reading is 
 fourteen to eighteen inches. The 
 farsightedness that occurs in youth 
 is caused by the eyeball being too 
 flat. In the farsightedness of old 
 age the lens has also lost its elas- 
 ticity, so that its shape cannot be 
 sufficiently changed to bring the 
 lights from near objects to a focus 
 on the retina. In farsightedness, 
 convex glasses are used, and in 
 nearsightedness, concave glasses 
 are used. Astigmatism * is a 
 defect caused by unequal curva- 
 ture of the cornea in different 
 directions. 
 
 Care of the eyes. Sight is priceless. (When reading is 
 mentioned in these suggestions, it is meant to include such 
 work as writing, sewing, embroidering, etc.) 
 
 1. It is important to have proper light. The light should 
 be steady, not flickering; we should not read after sunset 
 by the fading twilight ; we should not read with the sunlight 
 falling on the book; we should not read facing a window 
 or with a light directly in front, unless the eyes are protected 
 
 FIG. 197. Diagram of 
 the course of the retinal 
 nerve fibers. Light from A 
 strikes the outer part of the 
 right, and the inner part of 
 the left, retina. The fibers 
 from these parts go to the 
 right half of the brain, B. 
 N represents the nose. The 
 spots A and A on the retinae 
 are habitually stimulated 
 together. 
 
Sensation and the Special Senses 
 
 345 
 
346 
 
 Healthful Limng 
 
 by a shade. The best artificial light is that given in the 
 indirect or semi-indirect * method of illumination, either by 
 gas or electricity (Fig. 199). In such lighting there is no 
 glare. Is there glare on the blackboard in your room? 
 
 FIG. 199. Indirect lighting without glare. 
 
 This means that the windows are not placed properly. 
 Light curtains diffuse the light evenly, but dark curtains 
 cause lights and shadows. 
 
 2. The state of the eyes is of importance. We should not 
 read when tired or sleepy; when convalescing from an ill- 
 ness ; with the head bent down ; when the eyes are sore ; 
 when they are tired, unless we rest them every few minutes 
 by looking at far objects: when riding in jolting cars and 
 carriages ; when the circulation is impeded by tight clothing 
 around the neck. 
 
 " Tobacco blindness " sometimes results from smoking. 
 
Sensation and the Special Senses 
 
 347 
 
 The first symptom is color blindness, which is followed by 
 haziness of vision, and finally, by partial or complete loss 
 of sight. 
 
 3. The character of the object of vision is of importance. 
 The type from which books are printed should be large. 
 The paper should not be pure white or glazed, but a neutral 
 tint ; it should be opaque, so that the printing will not show 
 through from the reverse page ; the lines should not be more 
 than four and a half inches long. Publishers of magazines 
 are the worst offenders in using shiny glazed paper because 
 it brings out the beauty of fine engravings. 
 
 The sense of hearing. The ear brings to the auditory 
 area of the brain sensations derived from sound. These 
 sensations are received and transmitted by the auditory 
 nerve. For, the purpose of receiving it has a special sense 
 organ, the ear. 
 
 Structure and function of the ear. The ear may be de- 
 scribed in three parts, the outer, middle, and inner ear 
 
 Auditory 
 Nerve 
 
 Semi- Cir cula 
 C 'a nets 
 
 Middle Ear 
 with Bones 
 
 FIG. 200. Diagram of ear and Eustachian tube. 
 
 (Fig. 200). The outer ear consists of the cartilaginous 
 concha, the part that is usually spoken of as the " ear," 
 and the meatus, the canal leading into the head from the 
 lower part of the concha. Which part of the concha is not 
 
348 Healthful Living 
 
 cartilaginous but fatty tissue ? Part of the wall of the meatus 
 is of cartilage, but the deeper part has a wall of bone. The 
 entrance of the meatus is guarded by hairs, and its wall is 
 covered with a bitter wax secreted by glands in the lining. 
 Its inner end is closed by the tympanic membrane, which 
 is sometimes called the drum, but it is only a drum skin. 
 Three little bones stretch across the true drum, which is 
 the middle ear, to a small film separating the middle ear 
 from the internal ear. These three little bones are called 
 the hammer, anvil, and stirrup. The middle ear communi- 
 cates with the pharynx by a narrow tube called the Eusta- 
 chian tube. This tube is for the purpose of admitting air 
 to the middle ear, so as to equalize the air pressure on each 
 side of the membrane and prevent straining it. Sometimes 
 blowing the nose may press the air up into the middle ear 
 and press the walls of the Eustachian tube together and 
 close it. This causes slight deafness for the time. The 
 pressure may be relieved by holding the nose closed and 
 swallowing, thus opening the passage to the middle ear. 
 One end of the hammer is attached to the inner surface of 
 the drum skin ; the other end is attached to the anvil ; and 
 one prong of the anvil is attached to the stirrup, which in 
 turn is fastened by base to the small film stretched across 
 the round hole in the bone, opening into the inner ear, or 
 labyrinth. The inner ear consists of several cavities con- 
 taining a liquid in which rest the endings of the auditory 
 nerve. The endings of the nerve are elaborated into an 
 organ, the cochlea, for receiving sound waves and three 
 semi-circular canals which are concerned in equilibrium.* 
 
 Soimd waves, entering by the meatus, set the drum skin 
 to shaking; the vibrations are conveyed by the chain of 
 bones (Fig. 201) across the middle ear to the liquid of the 
 inner ear. The wave travels through air in the outer ear, 
 solids in the middle ear, and liquids in the inner ear. The 
 vibrations of the liquid, in the cochlea, start nerve impulses 
 
Sensation and the Special Senses 
 
 349 
 
 FIG. 201. Bones of right ear, enlarged ; 
 malleus, incus, and stapes. 
 
 in the fibers of the auditory nerve, and when these impulses 
 
 are received and interpreted in the brain, the miracle of the 
 
 conversion of the 
 
 external sound wave ~^ /ncus 
 
 into the sensation of 
 
 sound is complete. 
 
 It is now believed 
 that the semi-cir- 
 cular canals (Fig. 
 202) of the inner ear 
 are not concerned 
 in hearing. The 
 weight of the liquid 
 they contain press- 
 ing upon the nerve fibers located in them and exerting a 
 varying pressure according to the position of the body, gives 
 us the " equilibrium sense," which enables us to know the 
 position of the body at all times, that we may preserve its 
 equilibrium. Sight and the muscular sense also contribute 
 to maintain the equilibrium. 
 
 Care of the ear. The meatus is self-cleansing ; the wax 
 changes into dry scales, which fall out. The external ear 
 should be washed, but when we reach the passage, we should 
 
 go no deeper than 
 we can easily 
 reach with the 
 tip of the finger 
 covered with a 
 damp cloth ; es- 
 pecially the finger 
 should not be 
 forced into the 
 
 tender ears of children. A blow with the flat hand upon the ear 
 may force the air in and injure the tympanum. Picking the 
 ear with hard or sharp objects is dangerous to the tymimnum. 
 
 Vestibule 
 
 Sem/'-C/rcif/ar 
 Cana/s 
 
 Coch/ea 
 
 FIG. 202. The inner ear, or labyrinth. 
 
35 
 
 Healthful Living 
 
 Sometimes the wax collects in a lump near the drum, 
 causing deafness. The remedy is to syringe the meat us 
 with warm water until the lump is softened and comes away. 
 The bitter wax is a protection against insects. Quinine 
 often interferes for a time with the hearing. Chronic cold 
 in the throat reaching the ear through the Eustachian tube 
 sometimes injures the hearing. 
 
 The sense of touch. The four special senses of sight, 
 sound, smell, and taste are located in special organs. Touch 
 
 is located in all parts of 
 the body. When an 
 object touches the skin, 
 an impulse is taken to 
 the brain. There it gives 
 
 
 
 FIG. 203. Four papillse of the true 
 skin, magnified. The epidermis has 
 been removed. Most papillae contain 
 touch corpuscles. 
 
 touch (Fig. 203), com- 
 posed of temperature 
 
 *; 
 
 (warmth Or cold), pain, 
 
 Qr pressure . Three kinds 
 
 r 
 
 of sensations are thus in- 
 cluded in the general name of touch. Touch strictly gives 
 only such ideas as those of size, shape, location, smooth- 
 ness, hardness, and dampness. The ends of the fingers can 
 distinguish two points as separate points if they are only -^ 
 of an inch apart, while if the- two points are applied to the 
 back, they feel as if they were one point until they are 
 separated two inches. 
 
 The covering of epidermis not only protects the nerves 
 and the other delicate organs in the true skin, from injury, 
 but also modifies any impression, so that in producing a 
 sensation it is spread over several nerve endings instead of 
 one, and is thus turned into a gentle instead of a painful 
 sensation. 
 
 Temperature. Temperature may give warmth or cold 
 sensations. This part of the sense of touch is located only 
 
Sensation and the Special Senses 
 
 in certain points or spots, called heat spots and cold spots, 
 situated a small fraction of an inch apart (Fig. 204). Some 
 spots give a sensation of heat 
 only, and some of cold only. 
 The sense is so delicate that a 
 difference of -J- of a degree of 
 temperature between two ob- 
 jects can be detected. Ex- 
 tremely hot and cold objects 
 injure the cells and do not 
 give sensations of temperature 
 but only of pain. 
 
 Pain. A sensation greatly 
 increased or often repeated be- 
 comes unpleasant and is called 
 pain. The same physical in- 
 fluence may be felt at one 
 time as a pleasant touch, and 
 at another time as a pain, 
 depending upon the state of 
 the nerve tissue. When an 
 influence is becoming strong enough to endanger the body, 
 the simple sensation of touch becomes changed into one 
 of pain and warns us to avoid the danger. When a nerve 
 is laid bare and touched, or cut midway in its course, the 
 feeling is not one of touch, but of pain. Pain is a protec- 
 tion, and therefore more of a good than an evil. In many 
 diseases it is a prominent symptom, and the physician is 
 begged to give relief. But the wise physician hesitates 
 before giving morphine or other sedatives, knowing that to 
 drown the pain is to conceal the danger, and take away his 
 best evidence as to the state of this disease. At the same 
 time, he runs a risk of starting a habit in the patient of 
 deadening pain and hiding unpleasant feelings by taking 
 narcotics, a habit that may become fastened upon the 
 
 FIG. 204. Cutaneous "cold" 
 spots (light shading) and "hot" 
 spots (dark shading) ; anterior 
 surface of the thigh. 
 
352 Healthful Living 
 
 patient and ruin his life. Hence when sick we should bear 
 pain bravely. 
 
 Usually pain arising from the skin is located definitely by 
 the nervous sj^stem and the place is easily recognized. Pain 
 arising from an internal organ is located very inaccurately, 
 For example, the pain from a severe toothache may be felt 
 quite generally over the side of the face. Often the pain 
 from an internal organ is felt in a definite skin area and so 
 cutaneous pain in certain places refers to trouble in cer- 
 tain internal organs. For example, pains arising from the 
 stomach are located in the skin at the tip of the sternum; 
 pains from the heart in the region of the scapula. 
 
 Pressure. The sense of pressure is a part of the touch 
 complex. The pressure points in the skin are more numer- 
 ous than the temperature points and in the parts of the body 
 supplied by hairs these pressure points lie over the hair 
 follicles. This explains the delicate mechanism provided 
 in animals which can feel their way in the dark by the long 
 hairs of the face. What animals show such provision? It 
 has been found that after anesthetization of an area of the 
 skin, there remains a deep or subcutaneous sensibility to 
 pressure and movement. The nerves that enable us to 
 distinguish lighter pressures are associated with the recog- 
 nition of temperatures. 
 
 The muscular sense. When an object is lifted, it is 
 felt to be distinctly heavier if its weight is increased by only 
 j^, but when it is laid upon the skin, its weight must be 
 increased by before it feels heavier. Hence it is con- 
 cluded that sensations of weight and resistance to the muscles 
 depend upon the amount of muscular effort needed to over- 
 come the resistance as well as upon the feelings of pressure 
 upon the skin and body. Close your eyes and place the in- 
 dex finger of your right hand on your left eye. Are you 
 able to do this? Sensations coming from the muscles of 
 your arm, from the tissues of the joints of the arm, go to the 
 
Sensation and the Special Senses 353 
 
 brain and tell how to direct the hand. This sense is called 
 the muscle sense. It is of great service in maintaining the 
 balance in walking and in making coordinations. 
 
 General sensations of the body. We have besides the 
 special senses, the general sensations of hunger and thirst. 
 These two bodily sensations arise from conditions within 
 the body due to the chemical reactions or water content of 
 the tissues. 
 
 Hunger. The sensation of hunger is due to the con- 
 tractions of the empty stomach. It has been stated in the 
 past that hunger was due to a general need of the body for 
 food, but the sensation passes away long before there is 
 time for digestion and absorption to occur. In addition, 
 hunger may be appeased by taking only a small amount of 
 food. That contraction of the empty stomach produces 
 the sensation of hunger has been experimentally demon- 
 strated by Dr. Cannon of Harvard, and others have seen 
 by an opening in the abdomen so that the stomach could 
 be observed, that the stomach is contracted during the time 
 that the sensation of hunger persists. Eating between meals 
 keeps the stomach working so that at mealtime it is not 
 contracted and ready to digest the food. This is an im- 
 portant reason for not eating between meals. The contracted 
 state is an expression of its readiness to receive food and care 
 should be taken, therefore, not to have habits that produce 
 a relaxed stomach. 
 
 Thirst. The sensation of thirst is felt in the pharynx and 
 the nerves in this region have the power of giving this sensa- 
 tion. It has been learned that the cells of the body are 
 made of protoplasm and that this protoplasm is liquid. We 
 also remember that the cells are bathed in lymph. The 
 fluid content of the body in health remains nearly constant. 
 When we sweat, water is lost and we replenish that removed 
 by drinking more water. When the water content falls 
 below a certain point the nerves in the mucous membrane 
 
 2A 
 
354 
 
 Healthful Living 
 
 of the pharynx are stimulated by the blood, which has lost 
 the water. This gives us the sensation of thirst. 
 
 APPLIED PHYSIOLOGY 
 
 LABORATORY EXERCISES 
 
 Experiment 1. To study the sense of sight. 
 
 Material. Snellen Test Chart (Plate X, back inside cover), 
 and figure for testing astigmatism . (Fig. 205). 
 
 Method and Observation. 
 20 feet from the observer. 
 
 Place the Snellen chart a distance of 
 Have it placed at the level of the eyes 
 and in good light. The distance 20 
 feet is chosen, because at that distance 
 light comes into the eyes in parallel 
 rays. 
 
 Hold a book in front of one eye and 
 have the observer read the line marked 
 20 feet. If he can read the letters 
 correctly, the vision in that eye is 
 normal. If he can read only the 
 "40 feet" line, the vision is \. 
 
 Test the other eye in similar 
 fashion. 
 
 The test for astigmatism is made by 
 seeing at 20 feet if all the lines of the 
 chart (Fig. 205) are of equal width. 
 Some of the lines may appear heavier 
 or more distinct than others. 
 Experiment 2. To study the sense of hearing. 
 
 Method and Observation. At a distance of 20 feet have the 
 observer stand with one hand over one ear. At that distance, 
 whisper in a low voice and test whether or not the observer hears 
 and understands. The whispered voice will be heard at 20 feet 
 by the normal ear. 
 
 In similar fashion, test the other ear. 
 Experiment 3. To test color blindness. 
 
 Material. A set of standard color worsteds with their tints 
 and shades. 
 
 Method and Observation. Test the student with the different 
 colors anci note the difference in accuracy, 
 
 FIG. 205. Test for astig- 
 matism. Reading distance. 
 If this defect exists, the lines 
 that run in one direction will 
 appear more distinct than the 
 lines in other directions. 
 
Sensation and the Special Senses 355 
 
 Experiment 4. To analyze sunlight. 
 
 Material. Prism. 
 
 Method and Observation. Throw the rays of the sun after 
 passing through the prism upon a sheet of paper. Note what 
 colors are present in the spectrum. 
 Experiment 5. To test sharpness of vision. 
 
 Material. White thread and black card. 
 
 Method and Observation. Cover one eye and measure the 
 greatest distance at which the thread can be seen on the card. 
 Test each eye. Test both eyes. 
 
 Determine the greatest distance when the card is placed 30 and 
 60 degrees from the line of vision. 
 Experiment 6. To test change in iris. 
 
 Material. Two persons. 
 
 Method and Observation. Place subject facing window. Cover 
 one eye and on raising the hand, note the change in size of the pupil. 
 
 Compare size of pupil when looking at near and at distant objects. 
 Experiment 7. To test the dermal senses. (Fig. 204.) 
 
 Material. Drawing compass, scale graduated to millimeters, 
 fine horsehair, pencil, forceps, vessels of cold, lukewarm, and hot 
 water. 
 
 Method and Observation. (1) Place a straight piece of horse- 
 hair in forceps and determine the greatest length that will give 
 sensation of pressure. Then test the relative sensitiveness of the 
 palm and back of the hand, the cheek and lips, forearm and fore- 
 head. 
 
 (2) Determine the least that the points of the compass may be 
 separated and still be recognized as two points, when placed in 
 contact with the parts given in (1). 
 
 (3) Make slight pressure on the back of the hand with pencil 
 and determine the sensations that arise. 
 
 (4) Put finger of right hand into a vessel of warm water and 
 finger of left hand into a vessel of cold water. Notice the kind of 
 sensations that come from the two fingers. Does this sensation 
 change while the fingers are kept in the water? 
 
 Withdraw both fingers and place them at once into a vessel 
 of lukewarm water. What are the sensations experienced now? 
 Experiment 8. To test the sense of taste. 
 
 Material. Salt, sugar, vinegar, quinine. 
 
 Method and Observation. Test with the different substances 
 the tip, the sides, the back of the dry tongue and determine where 
 the sense of taste for the different substances is located. 
 
356 Healthful Living 
 
 GLOSSARY 
 
 After-image. The sensation of an object after the object ceases 
 to be present. 
 
 Aqueous humor. The water-like liquid in the front chamber of 
 the eyeball. 
 
 Astigmatism. A condition of sight in which the light rays which 
 come into the eye on the horizontal plane of the eyeball come 
 to a different focus than the rays that come in over the ver- 
 tical plane. It is due to a difference in the curvature of the 
 surface of the cornea. 
 
 Choroid. The middle layer of the eyeball. In this layer are the 
 blood vessels that supply the eye. 
 
 Convex-lens. A lens that is curved like the surface of a sphere. 
 
 Crystalline. Like a crystal, transparent, clear. 
 
 Dispensary. An institution at which sickness is treated and medi- 
 cines given. 
 
 Equilibrium. A state of control of the body ; balance. 
 
 Image. A visible representation of a thing. 
 
 Lens. A structure capable of directing rays of light. This 
 may be reflection to bring them to a point (as a sun mirror) 
 or to scatter them. 
 
 Perception. Understanding of the sensation that is received. 
 
 Pupil. The opening in the center of the eye caused by the arrange- 
 ment of the iris muscle. This muscle has a circular and radial 
 arrangement and can constrict or dilate the pupil. 
 
 Retina. The innermost layer of the eyeball. It is formed by 
 the branching endings of the optic nerve. 
 
 Sclera. The outermost layer of the eyeball. It is formed of con- 
 nective tissue and provides the eye with a firm capsule. 
 
 Semi-indirect. A variety of illumination. In this variety the 
 light units are suspended in a bowl-shaped structure from the 
 ceiling and rays of light are reflected downward from the ceil- 
 ing and also pass directly through the bowl. 
 
 Sensation. A conscious state resulting from a stimulus. 
 
 Stereoscope. An optical instrument for blending into one image 
 two pictures of an object. 
 
 Trachoma. A very contagious disease of the eye. It is commonly 
 called " sore eyes." 
 
 Vitreous humor. The glass-like liquid in the back chamber of 
 the eyeball. 
 
CHAPTER XVIII 
 SOME SPECIAL REGULATIVE PROCESSES 
 
 I. The Regulation of the Temperature of the Body. 
 II. The Regulation of Body Activity and Growth. 
 Thyroid secretion 
 Thymus secretion 
 Adrenal secretion 
 Pituitary secretion 
 Pancreatic secretion 
 III. The Control of the Voice. 
 The breath 
 The larynx 
 
 The resonant chambers 
 Pitch, volume, and quality 
 The care and culture of the voice 
 
 The regulation of the temperature of the body. Man 
 
 lives in the torrid zone and in the frigid zone, yet his tempera- 
 ture remains the same as he goes from one zone to another, 
 and as summer changes to winter. The temperature of the 
 healthy body is about 98.6 F. This is unmistakable evi- 
 dence that some means of maintaining a uniform temperature 
 exists in his body. This means for regulation of heat works 
 in two ways. The body controls its loss of heat as well as 
 its production of heat and under normal conditions both 
 means are used. Heat is lost from the body in the following 
 ways : 
 
 1. Through the excreta and waste of the body. 
 
 2. Through the expired air. This air is warmer than the 
 inspired air. 
 
 357 
 
358 Healthful Living 
 
 3. By the evaporation of moisture from the skin. This 
 heat loss is increased with the increase of perspiration. 
 
 4. By conduction and radiation of heat from the skin. 
 We can to some extent control this heat loss through 
 
 evaporation and radiation by wearing appropriate clothing. 
 In winter the clothing should be chosen to diminish this 
 heat loss and the material usually selected is wool. There 
 is also automatic control of the heat loss by reflex control 
 of the sweat nerves and the nerves to the blood vessels 
 (vasomotor nerves). These vasomotor nerves are appar- 
 ently under the guidance of a special center, so that a 
 greater or less amount of blood, as desired, may be sent to 
 the skin. On warm days the skin vessels are dilated; on 
 cold days they are contracted. 
 
 Heat is produced in the body by oxidation of food materials. 
 The body burns its food and so forms heat, and an increase 
 in good food gives more material for heat. Why do we eat 
 more in cold weather? This heat production is regulated 
 by the heat center or other controlling centers acting through 
 the nerves going to the muscles. It is also regulated by the 
 quantity and character of the food eaten and this is de- 
 termined by the appetite. Body heat, therefore, in its pro- 
 duction and in its loss is cared for by the body. By an 
 understanding of the physiology of the process, we may so 
 act as to assist the body. If we act contrary to the body 
 laws, we are working against the body. Write down in two 
 columns the ways in which the body may be assisted in heat 
 production and in heat loss. 
 
 The regulation of body activity and growth. It has been 
 learned that there are secretions which empty into the ali- 
 mentary canal through ducts leading from the secretory 
 glands. Now there are other glands which produce secre- 
 tions which they give directly to the blood stream and such 
 are called internal secretions. They are discussed under the 
 chapter on special regulative processes because they in- 
 
Some Special Regulative Processes 359 
 
 fluence the activity of organs through the body; in ad- 
 dition, some are concerned in the phenomena of growth and 
 development. If you have ever seen a cretin,* you have 
 seen a person who lacks one of these internal secretions, 
 that from the thyroid gland, situated in the neck. These 
 secretions are called hormones (from oTrvaco, arouse or excite) . 
 
 Thyroid secretion. The thyroid is a gland lying in the 
 middle line of the neck and just below the thyroid cartilage. 
 This secretion is necessary for proper physical and mental 
 growth. 
 
 Thymus secretion. The thymus is a gland that develops 
 until the age of 12-13 and then decreases in size. It lies 
 just above the heart. This gland gives an internal secretion 
 that is of great importance in the development of the child. 
 
 Adrenal secretion. The adrenals are small glands lying 
 on top of the kidneys. These glands give in their secretion 
 a substance, epinephrin, which acts as a stimulant to the 
 heart and blood vessels and serves to increase the blood 
 pressure. This gland becomes very active under emotional 
 conditions. The power that one has when stimulated by 
 fear or excitement to do a tremendous physical feat is given 
 by the epinephrin from the adrenals. 
 
 Pituitary secretion. At the base of the brain, lies a 
 little gland, the pituitary gland. This gland has two lobes, 
 an interior (front) and a posterior (back). The posterior 
 lobe furnishes a secretion which causes a rise in blood pres- 
 sure and slowing of the heart beat. The anterior lobe ap- 
 parently gives a secretion of importance in the growth of 
 the body and especially in the growth of bones. Increased 
 activity of this lobe of the gland is responsible for giantism.* 
 
 Pancreatic secretion. The pancreas gives a duct secre- 
 tion. What are its enzymes? It also gives a hormone 
 directly into the blood and this hormone is concerned in 
 the oxidation of sugar in the body. Disturbance of this 
 secretion, produces the disease known as diabetes. 
 
360 Healthful Living 
 
 It will be noticed, therefore, that the human body is very 
 complex in its regulation and control. Unseen forces are 
 at work directing its growth and controlling its development. 
 It is a mistake to believe that body health and vigor may be 
 obtained by the performance of formal gymnastic exercise 
 in the home or gymnasium. This human body must be 
 used with reference to its controlling mechanisms and its 
 evolutionary development. If man will use his body in 
 natural and wholesome ways of exercising it, eschewing 
 alcohol and tobacco, selecting good foods and pure water, 
 and obtaining fresh air and clean surroundings, then weak- 
 ness and disease will not be so common. The body in this 
 way will serve, as it should, as a fine and splendid temple 
 for the soul and the soul will be enriched. 
 
 The control of the voice. Man conveyed ideas in primi- 
 tive * times before the use of the voice, by gestures. To-day 
 this is called pantomime and as a means of conveying ideas 
 it is less necessary because man has the ability to express his 
 wants and desires by the spoken word. The voice, there- 
 fore, is the means of communication between individuals; 
 it is not the only means, however, nor should it be used alone 
 because the use of the muscles of the body in producing 
 movement and different forms of expression makes clearer 
 and more forceful the meaning of the thought conveyed by 
 the voice. The voice is used to convey ideas in song, and 
 this use is not only utilitarian but also may be such as to 
 give pleasure. Now whether the word is spoken or sung 
 there are certain important facts in the production of this 
 sound that are to be considered. The first of these is the 
 breath by which the sound is produced, the second is the 
 larynx in which the sound is produced, and the third is the 
 resonating chambers which modify and mold the sound. 
 The voice may be likened to a musical instrument in which 
 the breath is the motive factor, the larynx is the string in 
 the case of a violin, and the resonators are curves and flut- 
 
Some Special Regulative Processes 361 
 
 ings of the horn. In certain respects the voice resembles 
 more a violin and in others it may be likened to a horn. 
 
 It is verj^ important that the child learn to use the voice 
 properly and to this end there should be instruction in speak- 
 ing and singing. 
 
 The motor factor breath. For the production of sound, 
 air must be taken into the lungs and while under control 
 it is allowed to pass out over the strings in the larynx, thus 
 producing sound. In the chapter on respiration it was 
 learned that there were three ways of breathing: costal, 
 abdominal, and natural. Now, inasmuch as the diaphragm 
 is so important in supporting the sound produced you have 
 another reason why breathing should combine abdominal 
 and costal. This form of breathing will give more air and 
 at the same time will have it under better control. It is 
 very important that the parts of the body be adjusted in 
 the proper way and in this connection is it important to 
 remember the correct standing position. How often have 
 you seen girls and boys who were unable to speak plainly? 
 Did you notice that their standing position was very poor? 
 One who wishes to have a good voice must learn to stand 
 in a position that will allow the chest to have free and un- 
 obstructed movement and that will keep the abdomen well 
 drawn in. As a result, the larynx will be supported in the 
 proper place in the throat. 
 
 The weal instrument the larynx. The larynx, in 
 which the voice originates, is a cartilaginous box with three 
 sides, the sharpest corner forming a ridge in front (Fig. 206). 
 In many persons the larynx is prominent in the neck, and 
 is called the Adam's apple. The lid of the voice-box, or 
 larynx, is also of cartilage, and is called the epiglottis. 
 Across the middle of the box are stretched two bands, or 
 half curtains, called the vocal cords (Fig. 207). Their ends 
 are attached to the front and back of the larynx. They- are 
 not true cords, however, as they are thin and flat, and one 
 
362 
 
 Healthful Living 
 
 Epiglottis 
 ffyoicf JBor 
 
 edge of each band is attached to the side of the larynx. 
 
 Since the cords run across the middle of the chamber from 
 
 front to back, the free edges 
 are brought near together. 
 The slit, or opening between 
 these edges, is called the 
 glottis. During ordinary 
 respiration the cords are re- 
 laxed and the slit is wide 
 open. To make the voice, 
 the vocal cords must be 
 brought very near together 
 and drawn tight, and a cur- 
 rent of air must be forced 
 through the narrow slit to 
 throw the cords into vibra- 
 tion. The front ends of the 
 
 Larynx 
 
 Cricoid Cortifaae 
 
 FIG. 206. View of the right side 
 of the larynx, from the front. 
 
 cords are attached to the 
 larynx just within the angle, 
 or ridge, called the Adam's apple. The rear ends are 
 attached to two little movable cartilages at the back of 
 
 Left 
 Vocg/Cord 
 
 Right 
 Voca/ Cord 
 
 Arytenoid 
 Carti/age 
 
 207. Cross-section of the larynx above the vocal cords, 
 with the mucous membrane removed. 
 
Some Special Regulative Processes 363 
 
 the chamber. The moving of these little cartilages by the 
 muscles of the larynx brings the edges together and tightens 
 the cords. 
 
 Sound waves, or sound vibrations, are imparted to the 
 air by the tremulous motion of the cords. The limits of 
 the vibrations which the human voice is capable of making 
 are from 42 vibrations per second for the lowest tone, to 
 over 2000 vibrations per second for the highest tone. Lower 
 C of the soprano is produced by 256 vibrations per second. 
 The limits of vibrations which the human ear is capable of 
 hearing are from 16 to 50,000 vibrations per second, but 
 until they reach a rate of about 50, the sound is more like a 
 buzz than a tone. Some people cannot hear the voice of 
 mice, or the squeak of a bat, because the high pitch is be- 
 yond the limit of their hearing. 
 
 The resonant chambers. The vibration of the vocal 
 cords alone produces a weak, squeaky sound, but their vi- 
 
 FIG. 208. The shape of the mouth in sounding the vowels a, e, oo. 
 
 brations are reenforced or strengthened by the vibration 
 of the walls of the. lungs and trachea below, and of the nose 
 and mouth above (Fig. 208). These echoes, combining 
 with and ree'nforcing the vibration of the cords, determine 
 the quality of the voice. Just as the shape and material 
 of the walls of the violin give the quality to its tone, so the 
 shape and condition of the nasal passages, throat, etc., give 
 
364 
 
 Healthful Living 
 
 characteristic quality to each human voice (Fig. 209). If 
 the nasal passages are stopped up by catarrh, the person 
 is said to speak in a nasal tone, or through the nose, but 
 a " nasal " tone really results only when the sound can- 
 not come through the nose. Such a person's voice does not 
 change its quality when he speaks with his nose stopped 
 with his fingers. But a voice which has correct nasal 
 resonance * will change its quality when the nostrils are held. 
 Try it, and see whether your voice retains its nasal resonance. 
 Let one pupil read aloud at the back of the room where the 
 
 FIG. 209. The resonant chambers. A, resonance cavity of the nose; 
 B, resonance cavity of the mouth ; C, resonance cavity of the pharynx ; D, 
 soft palate ; E, tongue ; F, point at which vibration begins. 
 
 The figure on the left shows soft palate (D) in normal position, allowing 
 air in iiaso-pharynx to vibrate in unison with initial note. The middle 
 figure shows soft palate raised, shutting off the resonance and rendering tone 
 thin and hard. The figure on the right shows another common fault. The 
 tongue is lowered, increasing the size of the mouth cavity. This increases 
 the volume of the tone, but renders the quality harsh and hollow (Latson). 
 
 others do not see him, and find whether they can tell, by the 
 change in his voice, at which word he closes his nostrils in the 
 midst of the reading. The vocal cords are not used at all 
 in whispering. It is akin to whistling. In singing, single 
 sounds are more or less prolonged. In speech, the principal 
 changes are in the duration of the sound, and in the reso- 
 nance in the mouth. In whispering, audible breathing is cut 
 
Some Special Regulative Processes 365 
 
 off by the tongue and lips, and words are articulated, al- 
 though no sound comes from the vocal cords. A public 
 speaker ordinarily utters 125 words per minute. If there 
 are four sounds to a word, this amounts to 500 sounds each 
 minute or eight each second. 
 
 Pitch, volume, and quality. The rate of vibration of a 
 cord, and hence the pitch of a sound, are influenced in several 
 ways. Is the string of a violin or of a guitar tuned up or 
 down by tightening it? Which is higher in pitch, a long 
 or short string of a harp or a piano ? Which makes a higher 
 note, the light or the heavy string of a violin or a guitar? 
 The pitch of the note given by a string may be raised in 
 three ways : tightening, shortening, or decreasing the weight 
 of the string. From these facts explain why the voice rises 
 in pitch when we are excited, the muscles at that time be- 
 ing contracted with greater force. Why does a cold with 
 congestion of the cords cause a person to speak in a hoarse, 
 deep voice? Why does a man, whose larynx is larger than 
 a woman's, have the deeper voice? Why does a boy's voice 
 change as his larynx enlarges? 
 
 A man's voice has usually a pitch of one octave* below 
 that of a woman or a boy. The range of the human voice 
 is about two octaves. The voice may also vary in volume, 
 or loudness, as well as in pitch. How do we speak loudly 
 at one time and softly at another? If a tin pan is struck 
 gently, the sound is weak; if it is struck with force, the 
 sound is louder. We make the voice louder by stronger 
 expiration of the breath, thus sending the air with more 
 strength against the tightened vocal cords. Two persons 
 sing a song together in the same pitch and with the same 
 loudness ; yet you can readily distinguish a difference in 
 the two voices. This is because of a difference in quality, 
 which is the third variation possible in a voice. Sound in 
 wind instruments is strengthened by resonance, which is a 
 kind of instantaneous echo in the pipes. 
 
366 Healthful Living 
 
 The care and culture of the voice. The voice should not 
 be used more than is absolutely necessary when it is hoarse. 
 Catarrh may injure the voice by injury to the vocal cords 
 or by obstruction of the nasal passages. 
 
 The best way for a child to acquire distinct and refined 
 speech, is to hear it habitually. Great numbers of people 
 are handicapped by hasty, harsh, indistinct, or disagreeable 
 speech. Parents and teachers should remember as children 
 are growing up, what an advantage to them in after life a 
 refined, melodious voice will be. Nearly all children have 
 sweet voices when young, but many lose them before adult 
 life on account of acquired nervous habits, dusty and ill- 
 ventilated rooms, deformity of lungs due to restrictive 
 clothing, or from singing during the time their voices are 
 changing or attempting tunes beyond the compass of their 
 voices. 
 
 Smokers are frequent sufferers from affections of the 
 throat. Smoking may produce a constant " hacking " 
 cough. The hot, poisonous smoke, to say nothing of the 
 poisonous vapor of nicotine, brought in contact with the 
 vocal cords, is almost certain to produce mischief. Singers 
 and public speakers usually have to give up the use of tobacco 
 on this account. Cigarette smoking is especially bad for 
 the voice, as the smoke is inhaled. . The deep-toned voice 
 of the chronic drinker may be an indication of inflammation 
 of the larynx, a disease from which beer drinkers often suffer. 
 
 Methods of voice training vary, but it should be noted 
 that there is no special virtue in any one system. To train 
 the voice properly there must be considered the motor 
 factor, the vocal instrument, and the resonant chambers. 
 In some pupils one factor may need more emphasis than 
 the others and the successful teacher will meet the needs 
 of the pupil rather than pursue with every pupil a rigid 
 system. To secure a rich, resonant, and flexible voice is 
 the goal. Hence there must be no straining and no tense- 
 
Some Special Regulative Processes 367 
 
 ness. Breathing exercises that call for a rigid over-filled 
 
 chest destroy flexibility. Swedish formal gymnastics are 
 
 distinctly harmful in this respect because they make the 
 individual tense and rigid. 
 
 GLOSSARY 
 
 Cretin. A person suffering from cretinism. This condition is 
 caused by a deficiency in the secretion of the thyroid while 
 the individual is a child. 
 
 Giantism. A condition of the body in which all parts are enlarged 
 and the person appears as a giant. This condition results 
 from disturbed secretion of the pituitary gland. 
 
 Octave. The interval between any note and that note that gives 
 twice as many or hah 3 as many vibrations in a second. 
 
 Primitive. Pertaining to the earliest times, especially before 
 modern or ancient civilization. 
 
 Resonance. A prolongation or reinforcement of sound by means 
 of sympathetic vibration. The vibrations of the resonating 
 chamber must come at the same time as the vibrations of the 
 instrument producing the sound. 
 
CHAPTER XIX 
 BACTERIA AND DISEASE 
 
 I. Injury to the Body by Forces in Its Environment, 
 II. Microscopic Forms of Life. 
 Molds 
 Yeasts 
 Bacteria 
 The work of these organisms 
 
 III. The Effects of Bacterial Growth in the Body. 
 
 Ptomaines 
 Toxins 
 
 IV. The Germ Theory of Disease. 
 V. Antitoxins and Immunity. 
 
 Smallpox vaccination 
 
 Typhoid vaccination 
 VI. Injury of the Body by Poisons in Food. 
 
 Fish and shellfish 
 
 Meat poisons 
 
 Poisons in milk 
 VII. Injury of the Body by Physical Agents. 
 
 Heat exhaustion 
 
 Sunstroke 
 
 Electricity , 
 
 Mountain sickness 
 
 Caisson disease 
 VIII. Injury of the Body by Chemical Agents. 
 
 Lead poisoning 
 
 Other poisonous metals 
 IX. Diseases Caused by Mosquitoes. 
 
 Malaria 
 
 Yellow fever 
 X. Tuberculosis. 
 XL Prevention of Communicable Diseases. 
 
 Cleanliness of the mouth 
 368 
 
Bacteria and Disease 369 
 
 Drinking water 
 Food 
 
 Care of the bowels 
 Bathing 
 Sleeping 
 
 Prevention of influenza 
 
 XII. Table of Ways and Means of Communication of the Im- 
 portant Infections of Man. 
 
 XIII. How Bacteria Are Destroyed Within the Body. 
 
 XIV. How Bacteria Are Destroyed Outside the Body. 
 
 Disinfection 
 Antiseptics 
 
 XV. A Curious Theory of Disease. 
 XVI. Health Rules for School Children. 
 
 Injury to the body by forces in its environment. It is 
 very important to remember that the human body is the 
 kind of bod} r it is, because of the way in which the members 
 of the race have lived. For example, man has an alimentary 
 canal that requires a mixed diet, partly because in the growth 
 and development of the alimentary tract, a diet of flesh, 
 vegetables, grains, nuts, and fruits is used. Now the body 
 is injured if man in his foolishness tries to live only on nuts. 
 Also the body of man has developed with reference to exercise. 
 Man has inherited the need for exercise just as definitely 
 as he has inherited his biped position. Therefore, the man 
 or woman who sits in an office all day and does not par- 
 ticipate in games or sports or gymnastics of any kind, will 
 suffer from disturbances in the body due to the lack of 
 physical exercise. 
 
 The body may also be injured by attacks from forces out- 
 side the body, such as bacteria. These minute microscopic 
 animals are present in the air and water and are often found 
 on objects of all kinds. They cause disease by obtaining 
 an entrance into the body and growing there. As they 
 grow they produce poisons, which passing into the blood 
 2s 
 
370 
 
 Healthful Living 
 
 in the circulation, injure the body cells and in some cases 
 kill them. Protection from such forces, therefore, will be 
 obtained by preventing these bacteria from obtaining en- 
 trance to the body or by keeping the body so well that, 
 if they do get in, they cannot grow and develop. Do you 
 remember the parable of the sower ? Well, bacteria are like 
 seed. If they fall on stony ground (good, vigorous, healthy 
 bodies) they die; if the leucocytes and protective agents 
 in the blood are able and sufficient, they will play the part 
 of tares and birds in destroying the bacteria; but if the 
 bacteria come into the lazy, weak, inefficient body, they 
 will produce many fold. 
 
 Microscopic forms of life. As we trace back to their 
 origins the lines of development of the animal and plant 
 kingdoms, we find them converging to one common type, 
 a single cell organism, so simple in construction and so un- 
 specialized in function that it is impossible to tell whether 
 it is plant or animal. These cells are so small that 
 they can only be observed by means of the high power of 
 the microscope. They are much smaller than the cells of 
 the body. There are many different 
 forms, but the ones important for us to 
 know, are molds,* yeast, and bacteria. 
 
 Molds. Every one has seen fungus * 
 plants, such as mushrooms and puffballs, 
 that do not bear flowers but multiply by 
 spores. They live upon dead logs or where 
 there is much dead organic matter in the 
 soil. Imagine a fungus that grows on an 
 average about ^ of an inch in height ; this 
 is called mold (Fig. 210). It grows, for in- 
 stance, upon moist bread in warm weather. 
 Mold forms a kind of network as it grows 
 through any substance that will nourish it, and sends up stalks 
 with knoblike ends, the knobs being full of minute spores. 
 
 FIG. 210. Ring- 
 worm fungus in a 
 hair. 
 
Bacteria and Disease 
 
 37 1 
 
 Yeast. Think, if you can, of small plants only about 
 of an inch in length, and composed usually of one oval 
 cell, a plant that makes new plants by " budding," or the 
 forming of a smaller cell on the old one. 
 Yeast cakes consist of yeast plants scattered 
 among the grains of flour of which the cake 
 was made. Yeast plants multiply rapidly, 
 doubling in number in Iwo hours (Fig. 211). 
 They grow upon sugar, decomposing it into 
 alcohol and carbon dioxide. This process 
 
 called fermentation. In wine making, 
 
 s 
 
 FIG. 211. The 
 yeast plant. 
 
 alcohol is the product sought; in bread 
 
 making, carbon dioxide is the useful product, 
 
 this gas giving the bread its lightness, while the small amount 
 
 of alcohol formed is driven out by the heat in cooking. 
 Bacteria. But suppose the microscope shows a much 
 
 smaller organism 
 which averages 
 
 aoAoo of an inch in 
 diameter, a one-celled 
 
 organism that multi- 
 plies by division like 
 the amoeba and other 
 one-celled animals, 
 and lives upon albu- 
 minous substances; 
 only for its food, 
 This is a bacterium. 
 Bacteria are called 
 also microbes * or 
 germs ; and they are 
 
 FIG. 212. -The organism that causes pneu- 
 monia is a micrococcus and is called the pneu- 
 mococcus. These bacteria have a capsule 
 surrounding the organism. The large cells are 
 polymorphonuclear leucocytes. 
 
 the 
 ing 
 
 smallest of liv- 
 organisms. A 
 
 that k 
 . tU1U L 
 
 rod-shaped is Called 
 
372 
 
 Healthful Living 
 
 a bacillus ; a round-shaped bacterium is called a micrococcus ; 
 and if spiral, it is called a spirillium (Figs. 212, 213, 214). 
 Under favorable conditions abundance of food and con- 
 siderable warmth and moisture bacteria may double in 
 numbers every half hour. Thus millions may result from 
 even one in a short time. (You will comprehend this better 
 by referring to "geometrical progression" in your arith- 
 metic.) Dryness and cleanliness prevent their growth ; cold 
 
 retards their growth 
 and division, hence 
 the utility of ice in 
 preserving meat, 
 milk, fruits, and 
 other foods in warm 
 weather. 
 
 Can you now ar- 
 range the names 
 yeast, mold, and bac- 
 terium in order of 
 size? Can you give 
 the kind of material 
 that each uses for 
 , food? Can vou tell 
 
 FIG. 213. These bacteria are the cause of " 
 
 cholera and are called cholera spirilla. They DOW each multiplies, 
 
 have small hair-like processes which serve as tails Qr reproduces its 
 for locomotion. These are called flagellae. 
 
 kind? What is a 
 bacillus? For what is " microbe " another name? 
 
 The work of these organisms. Molds are nature's tools 
 for destroying hard and durable tissue like logs, bone, and 
 hides, which otherwise would not decay but would fill the 
 earth, leaving no room for living creatures. Ringworm is 
 caused by the growth of one form of mold within the skin. 
 It does not grow in a sound and clean skin. Falling of the 
 hair is often accompanied by the growth of mold in the hair 
 follicles, but it must be preceded by overheating and starving 
 
Bacteria and Disease 
 
 373 
 
 of the cells of the scalp by a tight hat, too much brain work, 
 or other cause. Yeast prevents the calamity of all plant 
 food accumulating in the form of starch and sugar. Bacteria 
 destroy the dead and excreted matter of vegetables and 
 animals so that it melts away and is stored in the soil, ready 
 to be utilized as plant food again. Mold, yeast, and bac- 
 teria are great blessings, for they are indispensable friends 
 of all other living 
 beings. They do 
 not always wait for 
 the dead or dying 
 material to be ex- 
 creted, or separated 
 from the animal or 
 plant, before attack- 
 ing and destroying 
 it. If more food is 
 eaten than can be 
 digested, and it re- 
 mains longer than 
 five hours in the 
 
 FIG. 214. The diphtheria bacilli are the 
 small rods shown in the picture. These organ- 
 isms are killed by antitoxin given to those who 
 have the disease. 
 
 stomach, starchy 
 
 food may ferment 
 
 by the action of 
 
 yeast plants, giving 
 
 rise to carbon dioxide gas, and albuminous .food may undergo 
 
 decomposition from the action of bacteria. 
 
 The effects of bacterial growth in the body. Ptomaines* 
 You learned that bacteria produce decay in unsound tissue. 
 They destroy the albumin in which they grow, producing 
 foul-smelling gases and a number of poisons called ptomaines, 
 if formed after death. Ptomaines cause most of the symp- 
 toms produced by eating decayed meat. A special kind of 
 ptomaine sometimes forms in milk and ice cream which 
 been kept for a long while. This is why ice cream 
 
374 
 
 Healthful Living 
 
 which has been melted, and frozen a second time, is 
 
 dangerous. 
 
 Toxins* The growth of bacteria in an unsound, living 
 
 body, produces poisons called toxins, which, circulating 
 
 among the sound tissues, produce weakness and disease. 
 
 Disease germs may grow upon the injured cells in an open 
 
 wound, causing offen- 
 sive matter to form. 
 Diphtheria (Fig. 
 214), typhoid fever 
 (Fig. 215), tuber- 
 culosis (Fig. 225), 
 cholera* (Fig. 213), 
 lockjaw* (Fig. 216), 
 and la grippe* are 
 all diseases in which 
 germs have been 
 proved to be present, 
 and all produce poi- 
 sonous toxins. 
 
 The germ theory 
 FIG. 215. Typhoid bacilli. The growth Q f disease. Loilis 
 
 of these organisms in the intestine produces 
 
 typhoid fever. Pasteur, the great 
 
 French scientist, 
 
 made possible the modern understanding of disease and 
 opened up the way for the treatment of many diseases that 
 had caused scourges and plagues * in the past. Robert Koch 
 explained and demonstrated the " germ theory of infectious 
 diseases " mainly as follows : 
 
 1. Each infectious disease is caused by a specific germ. 
 These germs may be found in the tissues or fluids of 
 the body affected and the products from the growth 
 of these germs are the poisonous agents which injure 
 the body and give the symptoms of the disease. 
 The germ of diphtheria is the Diphtheria Bacillus. The 
 
Bacteria and Disease 
 
 375 
 
 poisons from the growth of these germs in the throat give the 
 symptoms of the disease. 
 
 2. The specific germ taken from one body and introduced 
 into another body susceptible to the disease, will 
 produce in the second body the same disease. 
 
 Why do we have quarantine ? * In a recent epidemic of 
 infantile paralysis in New York City, a mother fearing to 
 take her child to a 
 hospital left her 
 home and traveled 
 with the sick child 
 to another part of 
 the city. Why 
 should she not have / ~ /,._o, 
 
 done this ? Did she / I / , f /<f / i / 
 
 expose other children 
 to the disease? 
 Should she have 
 been as thoughtful 
 of other children as 
 of her own child? 
 
 Why should we 
 not swap apples or 
 borrow handker- 
 chiefs ? 
 
 Antitoxins * and immunity.* Now it is known that one 
 attack of smallpox makes it impossible or very difficult for 
 that individual to have the disease again. This is true in 
 the main for all the communicable diseases. This protec- 
 tion against disease is called immunity, and is due to the 
 fact that the body manufactures protective substances to 
 kill the toxins (poisons) produced by the germs (bacteria). 
 These protective substances are called antitoxins and the 
 individual is said to b3 immune. This is an active immunity, 
 developed by the individual himself in the course of the 
 
 FIG. 216. Tetanus is commonly called 
 "lockjaw." It is caused by the bacilli shown 
 here. The "drum stick" form is characteristic 
 of the tetanus bacillus. 
 
376 Healthful Living 
 
 disease. Now it is possible to grow these substances in an- 
 other animal and then use the serum * from the blood of the 
 animal and inject it into man. This will give him a passive 
 immunity to the threatened disease. This procedure is used 
 in diphtheria epidemics. Smallpox vaccination * consists in 
 putting the smallpox virus in a small abrasion of the arm. 
 This produces the disease in a mild form and for about seven 
 years protects the body by the immunity conferred. 
 
 Smallpox vaccination. In 1776, E. Jenner of Berkeley, 
 England, learned that the milkmaids of the shire considered 
 accidental cowpox, caught while milking, a sure preventive 
 of smallpox. Twenty years later he began to vaccinate with 
 cowpox material to prevent smallpox. Vaccination protects 
 only for a few years. If exposed to smallpox, one should be 
 vaccinated, unless he has been vaccinated within the last 
 few years. Arm to arm vaccination is dangerous. Only 
 fresh virus from healthy cows should be used. If the arm 
 becomes very much swollen and disabled, it is a sign that 
 the blood has been poisoned by the use of impure material. 
 Some people are inclined to refuse vaccination for smallpox 
 (Fig. 217). Their argument is that there is no danger now 
 and they do not wish to inconvenience themselves or run 
 even the slightest risk. This is a very selfish attitude. 
 There is little danger to-day from smallpox, but this con- 
 dition of safety has been obtained by the systematic vac- 
 cination of people. Only a selfish person would wish to 
 derive security by the work and service of others and would 
 refuse to contribute his share for the safety of all. 
 
 Typhoid vaccination. Typhoid vaccination has produced 
 remarkable results in this respect also. Years ago in war, 
 more soldiers died from typhoid than from bullets. To-day 
 in the armies of France, England, and Germany, typhoid 
 is practically unknown due to the use of typhoid vaccina- 
 tion. Such evidence is important. The history of civiliza- 
 tion with its plagues, its Black Death and typhoid deaths in 
 
Bacteria and Disease 
 
 377 
 
 PRUSSIA 
 
 
 HOLLAND 
 
 
 AUSTXfA 
 
 With compulsory vaccination 
 and re-vaccination at 12yrs. 
 
 With compulsory vaccination 
 before entering school. 
 
 Without compulsory 
 vaccination. 
 
 Be, 
 the 
 
 r ore 
 Low- 
 
 Be t 
 
 the 
 
 fore 
 Law 
 
 
 
 
 
 
 After the Law 
 
 
 
 After the Law 
 
 
 
 
 
 
 
 of 1S73 
 
 
 
 of 1873 
 
 
 
 
 
 
 
 waspassed. 
 
 
 
 wasp&ssed. 
 
 
 
 
 
 
 
 
 
 
 Mi, .,ni 
 
 l.l.i 
 
 
 
 
 
 1868- 
 
 in<or-oocr>o <NPT*inio 
 
 1866- 
 
 
 
 1868- 
 
 
 1874 
 
 CO 
 
 1872 
 
 2 
 
 
 1874 
 
 
 
 Average 
 
 AnnualDeaths 
 
 Average 
 
 Annual Deaths 
 
 Average 
 
 AnnualDeoths 
 
 Yearly 
 Deaths 
 from 
 
 from 
 
 Yearly 
 Deaths 
 from 
 
 from 
 Sma//pox. 
 
 Yearly 
 Deaths 
 from 
 
 from 
 Sma//pox. 
 
 Smallpox 
 
 
 Smallpox 
 
 
 
 Smallpox 
 
 
 FIG. 217. Table showing value of vaccination (Carsten). 
 
378 
 
 Healthful Living 
 
 wars proves by contrast the value of the preventive measures 
 in use to-day. 
 
 The value of vaccination against typhoid is shown in a 
 report of Major Jester covering the period from 1908 to 
 1914. 
 
 VACCINATION AGAINST TYPHOID IN THE U. S. ARMY 
 
 YEAH 
 
 NUMBER OF 
 PERSONS VAC- 
 CINATED 
 
 NUMBER RE- 
 CEIVING THREE 
 DOSES 
 
 CASES op 
 TYPHOID 
 FEVER 
 
 ARMY, MEAN 
 STRENGTH 
 
 1908 i 
 
 
 
 
 
 239 
 
 74,692 
 
 19091 
 
 830 
 
 621 
 
 282 
 
 84,077 
 
 1910 i 
 
 16,093 
 
 11,932 
 
 198 
 
 81,434 
 
 1911 ! 
 
 27,720 
 
 25,779 
 
 70 
 
 82,802 
 
 19122 
 
 40,057 
 
 All 
 
 27 
 
 88,478 
 
 1913 2 
 
 25,086 
 
 All 
 
 4 
 
 90,752 
 
 1914 2 
 
 35,902 
 
 All 
 
 7 
 
 92,877 
 
 Injury of the body by poisons in food. Food that is not 
 fresh undergoes fermentation and decomposition. In this 
 change poisons are formed which taken into the body cause 
 disturbances and in some cases death results. 
 
 Fish and shellfish. Fish that is not fresh should not be 
 eaten. The signs of freshness in a fish are firmness of the 
 flesh, protruding eyes, red gills, and a clean fish. Mussels, 
 oysters, and lobsters decompose rapidly and produce serious 
 illness unless absolutely fresh. 
 
 Meat poisons. Animals that are ill, should never be used 
 for food. Meat that is spoiled is unwholesome and should 
 not be eaten. Sausages and other made meats are less 
 wholesome than fresh meats. 
 
 Poisons in milk. Milk may carry germs and in this 
 way infect persons using the milk. To prevent this the 
 
 1 Voluntary vaccination. 2 Compulsory vaccination. 
 
 In the years 1908-1911 the vaccination was voluntary. Beginning in 1912, 
 it has been compulsory. Since 1912, the cases of typhoid 27, 4, 7 were in 
 men who were not vaccinated, for some reason or other, or who had con- 
 tracted the disease before enlistment, with few exceptions. 
 
Bacteria and Disease 
 
 379 
 
 milk is often pasteurized * (heated from 150 to 155 F. for 
 20-30 minutes). In preventing the transmission of dis- 
 ease germs, greater emphasis should be placed on the method 
 of obtaining the milk. The dairyman should have clean 
 pails, and clean hands, and the udder of the cow should be 
 cleaned before milking. The farmer who takes the milk 
 pail from the fence and, without washing his hands, milks 
 the cow which has been standing in a dirty stable, is not 
 getting clean milk. Furthermore, he is neglecting a duty and 
 responsibility he owes to 
 his family and his neigh- 
 bors. 
 
 The poisons and dirt 
 in milk are real sources 
 of danger to the body, 
 but they can be elimi- 
 nated by careful gather- 
 ing and distribution of 
 the milk supply. The 
 cows should be cared for 
 in a sanitary stable and 
 every means used to keep 
 them clean and healthy. 
 Cows should be cleaned preparatory to milking. Covered 
 pails for milking should be used in order to keep the milk 
 free from dirt (Fig. 218). 
 
 It is also very important to keep the milk clean after it 
 is gathered. All bottles should be sterilized * and the hands 
 should not come in contact with the milk or inside of the 
 bottle. The best method of bottling milk is by machinery. 
 Milk is sometimes sold in bulk, from cans. Such milk, 
 even if gathered carefully, is liable to be contaminated. Flies 
 and dirt should not gain access to the milk at any time. 
 Compare the two pictures in Figure 219 and be prepared 
 to state all the advantages in the method shown in the lower 
 
 FIG. 218. Two kinds of milk pails. 
 % ; the cov - 
 
Healthful Living 
 
 picture. In spite of the care exercised in many places in 
 gathering the milk, a certain amount of infectious material 
 gains entrance to the milk after it is gathered. To prevent 
 
 Courtesy of Metropolitan Life Ins. Co. 
 FIG. 219. Two ways of distributing milk. 
 
 these organisms getting into the body and so causing dis- 
 ease, pasteurization is very widely practiced. Communi- 
 ties after pasteurizing the milk supply have noticed a drop 
 
Bacteria and Disease 
 
 in the amount of sickness and number of deaths. When 
 the infants in the care of the City of New York (Randall's 
 Island) were fed on milk that was not pasteurized the death 
 rate was as follows : 
 
 YEAR 
 
 NUMBER OP 
 CHILDREN 
 
 NUMBER op 
 DEATHS 
 
 PER- 
 CENTAGE 
 
 1895 
 
 1216 
 
 511 
 
 42.02 
 
 1896 
 
 1212 
 
 474 
 
 39.11 
 
 1897 
 
 1181 
 
 524 
 
 44.36 
 
 Total 
 
 3609 
 
 1509 
 
 41.81 
 
 This milk was gathered from a carefully selected herd pas- 
 tured on the island. In the early part of 1898 a pasteuriz- 
 ing plant was installed on the island and the milk given to 
 the children was pasteurized. No other change was made 
 in the diet. The record for the next seven years was as 
 follows : 
 
 YEAB 
 
 NUMBER op 
 CHILDREN 
 
 NUMBER OF 
 DEATHS 
 
 PER- 
 CENTAGE 
 
 1898 
 
 1284 
 
 255 
 
 19.80 
 
 1899 
 
 1097 
 
 269 
 
 24.54 
 
 1900 
 
 1084 
 
 300 
 
 27.68 
 
 1901 
 
 1028 
 
 186 
 
 18.09 
 
 1902 
 
 820 
 
 181 
 
 22.07 
 
 1903 
 
 542 
 
 101 
 
 18.63 
 
 1904 
 
 345 
 
 57 
 
 16.52 
 
 Total 
 
 6200 
 
 1349 
 
 21.04 
 
 It will be noticed that the total number of deaths in seven 
 years is less than the total in three years with raw milk. 
 Professor Fisher gives the value of a human life in dollars 
 
382 Healthful Living 
 
 as being $950 at the age of five years. Counting the average 
 of these infants to be five years, what was the yearly sav- 
 ing to the city by the installation of this plant. Beyond this 
 hypothetical saving there was a real saving in nursing and 
 hospital supplies, medical care, and the cost of burial. 
 
 Injury of the body by physical agents. The body may 
 be injured by forces coming in contact with it from the out- 
 side. These forces may be bacteria or they may be heat, 
 chemical, etc. The prevention of injury due to physical 
 forces will be important and of value in maintaining our 
 health. 
 
 Heat exhaustion. The main cause in this is heat. It 
 may come from the sun or from a furnace. Individuals who 
 indulge in alcohol are easily attacked. It occurs often in 
 armies on the march. Clothing fit only for cold weather 
 worn on hot days predisposes one to sunstroke. 
 
 Sunstroke. This condition is caused by the sun's rays. 
 Care must be taken not to expose the body to too great 
 
 465 Cases of Sunstroke, 1896 
 
 Heavy Dr/nkers 3O% Moderate Drinkers 50% Abstainers 20% 
 
 Drinkers Furnished 8O% of the Cases 
 
 70 Deaths from Sunstroke 1896 
 
 Abstainers 
 ffeavy Drinkers 60% Moderate Drinkers SO % /Q% 
 
 Drinkers Furnished 9O% of the Cases 
 
 Copyright, 1913, by Scientific Temperance Federation, Boston, Mass. 
 
 FIG. 220. Alcohol and Sunstroke. Statistics U. S. Weather Review, 
 November, 1896. 
 
 heat of the sun. The clothing in hot weather should be 
 light and loose. Alcohol in any form lowers the resistance 
 so much that sunstroke easily occurs in persons who use it 
 (Fig. 220). 
 
Bacteria and Disease 383 
 
 Electricity. Great electrical plants, used in industry, 
 are a source of danger. Individuals should not go near 
 these machines unless engaged in caring for them. In no 
 case should one enter a dynamo * room with wet clothing. 
 Electric wires and connections in the home should be in- 
 sulated and repairs should always be made by an electrician. 
 
 Mountain sickness. When coming into a mountainous 
 region from low altitude, care should be taken not to engage 
 in mountain climbing the first day. Time is necessary for 
 adjustment of the body to tjie new conditions. Mountain 
 climbing should be engaged in only by the vigorous and 
 strong. 
 
 Caisson* disease. Men who work underground in tunnels 
 and mines in an air of high pressure suffer cramps and 
 paralysis on emerging into the air above ground unless the 
 ascent is very gradual. Laws in some states compel em- 
 ployers to control this change. But for such workers it is 
 very important to know that " bad physical health, diseases 
 of the kidneys or heart, alcoholism, obesity, and hunger are 
 contraindications * for subjecting one's self to the high at- 
 mospheric pressure." 
 
 Injury of the body by chemical agents. Chemicals, when 
 brought in contact with the skin, may burn it, and when 
 taken into the system they injure the body cells. 
 
 Lead poisoning. Alcoholism again plays a prominent 
 part in increasing the susceptibility to lead poisoning. 
 Lack of cleanliness is also to be considered, and workers in 
 industries where lead is used should have the hands clean 
 when food is eaten. There is a popular tradition among 
 lead workers that chewing tobacco is a preventive of the 
 disease but this is not so. 
 
 The most dangerous trades connected with the use of 
 lead are, lead mining and smelting, zinc smelting, working 
 in white lead and lead colors, making lead pipes and other 
 lead objects, type making and type setting, and working in 
 
Healthful Living 
 
 electric storage-battery factories. Painters and workers in 
 ceramics and rubber goods frequently suffer from the lead 
 used in manufacture, if they are not careful. Cleanliness 
 
 FIG. 221. Mosquitoes. Comparison of 
 
 The non-malarial Genus Culex. 
 Palpi short. 
 Wings not spotted. 
 Legs sometimes spotted. 
 Position at rest, parallel to surface. 
 
 Larva, or wiggle-tail, breathes, and 
 rests perpendicular to surface of 
 water. 
 
 The malarial Genus Anopheles. 
 Palpi long. 
 
 Wings sometimes spotted. 
 Legs- not spotted. 
 Position at rest with abdomen and 
 
 hind legs elevated at an angle to 
 
 surface. 
 Larva, or wiggle-tail, is parallel 
 
 to surface of water when it 
 
 breathes. 
 
 The sucking tube and feelers are long in both genera. The long palpi of 
 the malarial genus furnish an infallible sign. The palpi are found on each 
 side of the sucking tube. The feelers are next to the palpi. 
 
 and avoidance of alcohol are the things to be remembered 
 by these workers. 
 
 Other poisonous metals. Mercury, phosphorus, tin, cop- 
 per, brass, and zinc poisoning occur among workers with 
 these metals. Pure air in the factory, sanitary floors and 
 
Bacteria and Disease 
 
 385 
 
 windows, cleanliness in the worker, avoidance of alcohol 
 these are the measures for prevention. 
 
 Diseases caused by mosquitoes. It has been learned 
 that the mosquito can carry parasites * in the salivary glands 
 and inject them into the blood of man with its sting. 
 
 Malaria. This disease is caused by the bite of a par- 
 ticular mosquito, called the anopheles (Fig. 221), which at 
 some time before has bitten a person having malaria. You 
 
 
 
 a 
 
 FIG. 222. Reproduction of the malaria parasite in a red blood cell, 
 a, entering the cell ; b, within the cell ; c-h, development and segmentation 
 of the parasite ; i, rupture of red cell setting young parasites free ; j, one of 
 them entering a red cell. This process goes on with continual destruction 
 of the red blood corpuscles until the parasites are killed by medical treat- 
 ment. 
 
 see in this way the mosquito transmits the disease. Pre- 
 vention aims, therefore, to kill mosquitoes of this particular 
 kind and to prevent the mosquito from biting a person having 
 the disease. The mosquito breeds in water and so the breed- 
 ing places of the insect should be destroyed. Stagnant pools 
 and swamps are covered with oil which kills the young. 
 Empty cans on rubbish piles should be buried so that no 
 water can collect in them. Boy scouts may do a' "good 
 turn " by organizing a " Mosquito Day." Mosquitoes may 
 
386 Healthful Living 
 
 be stunned in the house by burning fresh leaves of eucalyptus 
 or pyrethrum powder and then killed before they revive. 
 Persons in malarial regions and persons suffering from 
 malaria should live in houses that are well screened. 
 
 A person does not get malaria 
 from bad water, food, exposure to 
 sun, night air, or in any way 
 except by the bite of a mosquito 
 which has sucked the blood of a 
 person who has malaria. The 
 mosquito serves to transmit the 
 parasites which cause the disease, 
 and they are transmitted in no 
 other way. 
 
 FIG. 223. Larva of a culex _ T71 J ., .. . . 
 
 mosquito. When a mosquito, which has 
 
 previously bitten a person having 
 
 malaria, bites another person, the parasites are conveyed 
 into the blood of the second person. These parasites enter 
 the red blood cells and develop and increase in number as 
 shown in Figure 222. 
 
 The female mosquito lays her eggs on the surface of stag- 
 nant or still water and in a few days these hatch into larvse,* 
 often called " wigglers." The larvse develop into pupse and 
 finally into mosquitoes. All stages in this development 
 occur in water. The larvse of anopheles require from twelve 
 to sixteen days in warm 
 weather to mature. These 
 larvse may be distinguished 
 
 from the larvae of other and ^^^l^^tll^ 
 harmless mosquitoes by the 
 
 position they take in the water. The anopheles live at the 
 top of the water and parallel to its .surface (Figs. 223, 224). 
 
 The anopheles can best be destroyed by getting rid of 
 them in the larval stage. All brush and weeds surrounding 
 dwelling houses and mosquito breeding places should be cut 
 
Bacteria and Disease 
 
 387 
 
 down. The breeding places can be destroyed by draining, 
 filling, or oiling. By draining or filling, the water necessary 
 for the deposit of eggs is removed ; by oiling the water, a 
 thin film of oil is formed that prevents the larvse from getting 
 air and so they die. If oiling is the method chosen, it should 
 be done every fourteen days. 
 
 Yellow fever. This disease at one time was not con- 
 trollable because it was not known how the infection * was 
 carried. Now it is known that the mosquito, Stegomyia 
 fasciata, carries the disease. The preventive measures in 
 malaria apply here. 
 
 Tuberculosis. As the tubercle bacilli (Fig. 225) multiply 
 in the body, tiny tubercles are formed ; hence the name. 
 Tubercles are growths shaped like pin heads, and they may 
 be formed in any 
 tissue of the body. 
 You have learned 
 that in thousands 
 of cases bacilli in- 
 jure a part of a 
 lung and it heals 
 over. But in 
 thousands of cases 
 the individuals have 
 lived wrong physi- 
 cally for so long, and 
 their lungs have be- 
 come so weak, that 
 they are gradually 
 destroyed by the 
 bacilli. 
 
 FIG. 225. Tubercle bacilli in sputum of a 
 person having tuberculosis of the lungs. 
 
 Whether the body has been injured through ignorance 
 or self-sacrifice, through dissipation or selfish ambition for 
 money or fame, through foolish attempts at beauty, through 
 devotion to learning, or through some unselfish love and 
 
388 Healthful Living 
 
 work for others, the result is the same.; nature knows no 
 difference. However noble the character or wise the mind, 
 when a vital organ has sunk in health below the standard 
 necessary for a human being, deterioration comes. 
 
 Bacilli may be found in the sputum in an early stage of 
 tuberculosis. Then recovery is more difficult, but it will 
 often come if the person returns to natural ways, living out 
 of doors and allowing the forces of health to purify the body. 
 
 Many people die from tuberculosis and yet in many cases 
 the disease would not occur if proper care had been exercised 
 by the individual, or by those who have the disease. If one 
 who has the disease is careless and distributes the germs 
 and if those who have not the disease are careless in matters 
 of hygiene, there exists a situation which makes it easy for 
 one person to infect many. No one desires this to occur. 
 All must work against such spreading of infection. 
 
 Now it is known that the sun's rays destroy the bacillus 
 of tuberculosis. A man by the name of Twitchell found 
 that the sputum containing tubercle bacilli exposed to direct 
 sunlight for seven hours, could not produce the disease, and 
 the same sputum kept in a closed darkened bedroom with 
 carpeted floor and heavy hangings, caused the disease even 
 after thirty-nine days. Are the sun's rays valuable ? Should 
 the floor be covered with carpets or with rugs ? 
 
 Children from earliest infancy should be accustomed to 
 fresh air. Babies four weeks old should be taken out of 
 doors and even newborn babies should sleep in a room with 
 the window open. If the baby at home is bottle fed, the 
 milk used should be from cows that have been tested by 
 tuberculin * for tuberculosis and the milk should be pas- 
 teurized. Do you know of a baby living on cow's milk? Is 
 the milk pure ? Is the milk pasteurized ? 
 
 Prevention of communicable diseases. Many of the 
 diseases of the body are caused by the germs of the disease 
 gaining entrance to the body. If the entrance can be pre- 
 
Bacteria and Disease 389 
 
 vented, the disease will be prevented. In addition, the body 
 must be made strong and healthy so that the germs which 
 break through the blockade, Health Care, will be destroyed 
 by the forces present in the body. To prevent the entrance 
 of germs we should consider : 
 
 Cleanliness of the mouth. The teeth must be kept clean 
 by brushing at least twice daily. All cavities must be filled. 
 
 Drinking water. The water used for drinking should be 
 pure. Pure drinking water is tasteless, odorless, sparkling, 
 without organic matter, and without disease germs. 
 
 Clean food. Food taken into the body to build our 
 bodies should be clean. People should never eat at dirty 
 restaurants. If restaurants were chosen on the basis of 
 cleanliness, by all people, there would not be any dirty ones 
 left they would have to " clean up " or " get out." Chil- 
 dren in the cities should not buy food from street venders 
 who expose their food to dust and dirt and flies. 
 
 Care of the bowels. The waste of the body must be re- 
 moved daily and regularly. The best time for this elimina- 
 tion to occur is after breakfast. No exception to this habit 
 should ever be allowed. 
 
 Bathing. The body should be bathed daily in certain 
 parts, and the entire body should be washed at least once 
 a week. A shower bath is the most sanitary form of bath. 
 Rural schools and homes without running water can arrange 
 for showers by providing a perforated pail suspended so that 
 it can be filled and can distribute the water in a spray!. 
 
 Sleeping. One should be accustomed to fresh air and, 
 therefore, open windows at night are very important. Even 
 in cold weather the window of the sleeping room should be 
 partly open. The number of hours of sleep which children 
 of different ages should have are given on page 325. 
 
 Prevention of influenza. The very serious epidemic of 
 influenza in the United States in the fall of 1918, caused 
 more deaths in the army and civil population " over here " 
 
39 Healthful Living 
 
 than were caused by German bullets in the U. S. Army 
 "over there." Jn prevention of the disease, the factors 
 which have been repeatedly mentioned as important hygienic 
 practice, are the ones most effective. In this connection it 
 is instructive to learn the memorandum for strengthening 
 personal resistance, which was issued September 27, 1918, 
 by the Office of the Surgeon-General, U. S. A. 
 
 "HOW TO STRENGTHEN OUR PERSONAL DEFENSE 
 AGAINST SPANISH INFLUENZA" 
 
 1. Avoid needless crowding influenza is a crowd disease. 
 
 2. Smother your coughs and sneezes others do npt want the 
 germs which you would throw away. 
 
 3. Your nose, not your mouth, was made to breathe through 
 get the habit. 
 
 4. Remember the three C's a clean mouth, clean skin, and 
 clean clothes. 
 
 5. Try to keep cool when you walk and warm when you ride 
 and sleep. 
 
 6. Open the windows always at home at night ; at the 
 office when practicable. 
 
 7. Food will win the war if you give it a chance help by 
 choosing and chewing your food well. 
 
 8. Your fate may be in your own hands wash your hands 
 before eating. 
 
 9. Don't let the waste products of digestion accumulate 
 drink a glass or two of water on getting up. 
 
 10. Don't use a napkin, towel, spoon, fork, glass or cup which 
 has been used by another person and not washed. 
 
 11. Avoid tight clothes, tight shoes, tight gloves seek to make 
 nature your ally, not your prisoner. 
 
 12. When the air is pure breathe all of it you can breathe 
 deeply. 
 
 CHARLES RICHARD, Brig. Gen. M. C., Act. Surg.-Gen. U.S.A. 
 
 It will be seen that we must be careful to keep our bodies 
 so strong by careful living that no germs can enter. The 
 following table shows the ways and means of infections that 
 are common and important : 
 
Bacteria and Disease 
 
 TABLE OF THE WAYS AND MEANS OF COMMUNICATION OF THE 
 IMPORTANT INFECTIONS OF MAN 
 
 DISEASE 
 
 FROM 
 CONTACT 
 
 WITH SlCK 
 
 PERSON OR 
 ANIMAL 
 
 FROM 
 CONTACT 
 
 WITH 
 
 THINGS 
 SICK HAVE 
 USED 
 
 DRINKING 
 WATER 
 
 CAN 
 
 CARRY 
 THE GERM 
 
 FOOD 
 
 CAN 
 
 CARRY 
 
 THE 
 
 GERM 
 
 AIR 
 
 CAN 
 
 CARRY 
 
 THE 
 
 GERM 
 
 ANI- 
 MALS 
 
 CAN 
 
 CARRY 
 
 THE 
 
 GERM 
 
 INSECTS 
 CAN CARRT 
 THE GERM 
 
 Anthrax . . 
 
 yes 
 
 yes 
 
 
 yes 
 
 yes 
 
 cattle 
 
 flies 
 
 Cholera . . 
 
 yes 
 
 yes 
 
 common 
 
 yes 
 
 
 
 flies 
 
 
 
 
 way 
 
 
 
 
 
 Diphtheria 
 
 common 
 
 bedding 
 
 
 yes 
 
 yes 
 
 
 flies 
 
 
 way 
 
 etc. 
 
 
 
 
 
 
 Erysipelas . 
 
 yes 
 
 yes 
 
 
 yes 
 
 
 
 
 Influenza 
 
 chief 
 
 yes 
 
 
 
 yes 
 
 
 
 
 way 
 
 
 
 
 
 
 
 Malaria . 
 
 
 
 
 
 
 
 mosquito 
 
 
 
 
 
 
 
 
 only 
 
 Measles . 
 
 common 
 
 yes 
 
 
 
 yes 
 
 
 
 
 way 
 
 
 
 
 
 
 
 Mumps . . 
 
 yes 
 
 yes 
 
 
 
 yes 
 
 
 
 Rabies , ... 
 
 only 
 
 
 
 
 
 dogs 
 
 
 
 way 
 
 
 
 
 
 
 
 Scarlet . . 
 
 common 
 
 yes 
 
 
 yes, 
 
 yes, 
 
 
 
 fever .' .. 
 
 way 
 
 
 
 milk 
 
 skin 
 
 
 
 Trachoma . 
 
 common 
 
 yes, 
 
 
 
 yes 
 
 
 flies 
 
 
 way 
 
 towels, 
 
 
 
 
 
 
 
 
 etc. 
 
 
 
 
 
 
 Tubercu- 
 
 yes 
 
 yes 
 
 
 yes, 
 
 yes 
 
 cattle 
 
 flies 
 
 losis . . 
 
 
 
 
 milk 
 
 
 
 
 Typhoid 
 
 rarely 
 
 yes 
 
 common 
 
 yes, 
 
 
 
 flies 
 
 fever . . 
 
 
 
 way 
 
 milk 
 
 
 
 
 Wound 
 
 
 
 
 
 
 
 
 infections 
 
 
 
 
 
 
 
 
 such as cuts, 
 
 
 
 
 
 
 
 
 boils, etc. . 
 
 yes 
 
 yes 
 
 
 yes 
 
 yes 
 
 
 flies 
 
392 
 
 Healthful Living 
 
 How bacteria are destroyed within the body. If, in 
 
 spite of keeping the body in a splendid condition of health, 
 virulent bacteria gain an entrance to the body, even then the 
 body is often able to defend itself successfully by the fol- 
 lowing forces at its disposal : 
 
 First The white blood cells have as their chief function 
 to seek out bacteria and to devour and destroy them. This 
 explains why so many germs are necessary to transmit a 
 disease. If only a few are present, these cells will be able 
 
 to protect the body. If 
 the infection is too great, 
 or if the infecting bac- 
 teria are too virulent, 
 then these cells may fail 
 (Fig. 226). 
 
 Second The plasma 
 of the blood contains 
 substances which are able 
 way not fully 
 
 FIG. 226. A, germ destroyed by white 
 blood cell ; B, cell destroyed by germs 
 and the germs multiplying. 
 
 in some 
 
 known to inhibit the 
 action of bacteria. These 
 
 substances are called antibodies * and are developed by the 
 body during the course of the infection. Now these de- 
 fenses are dependent in a very definite way upon the 
 general health of the body for success. The action of 
 these cells is more pronounced in one with vigorous 
 health. It has never been proved that bacteria will 
 cause disease in a perfectly healthy body and, therefore, 
 it is important to keep the body in a fine state of health, 
 in order to prevent the great loss occasioned by illness. It 
 is perfectly true that many bacteria seem to be harmless 
 under certain conditions, but, if they find a weakened con- 
 dition, they seem to change their nature and begin the forma- 
 tion of poisonous toxins. Disease occurs then in a large 
 measure because people do not care for themselves properly. 
 
Bacteria and Disease 393 
 
 How bacteria are destroyed outside the body. The sun is 
 the great destroyer of all bacteria in summer and in tropical 
 climates. Cold destroys them in winter and in cold climates. 
 Wind drives away bacteria. It is almost impossible to trans- 
 mit disease in the open air. Some germs feed upon other 
 germs. In the soil are certain kinds of germs which oxidize 
 all organic matter, including other kinds of germs. Thus 
 germs can filter through only a few feet of sand before they 
 are destroyed. Well-water is safe to drink if no impurities 
 reach the soil near the well, but where the ground becomes 
 soaked with germ-laden sewage, impurities penetrate farther 
 and well-water is unsafe. 
 
 Cleaning with soap and water removes germs. Drying 
 kills many germs, but some species are harder to kill when 
 dry ; in that condition they will stand even freezing. Heat 
 equal to that of boiling water, applied for 15 minutes, will 
 kill almost every kind of germ. If the germs are killed by 
 a boiling temperature it does no harm to leave air in the 
 top of canned vegetables and jars of preserves. Milk is a 
 nourishing soil for germs which cause stomach trouble with 
 bottle-fed babies, unless the milk has been pasteurized and 
 the bottles sterilized. 
 
 Disinfection. For many years it has been the practice 
 to disinfect the rooms of people recovering from communi- 
 cable diseases, such as measles and diphtheria. The idea ex- 
 pressed in such a procedure was to kill the germs that were 
 in the room inhabited by the sick person. In Providence, 
 R. L, and New York City this practice has been abandoned 
 and health officers in other places are paying more attention 
 to cleanliness by soap and water. It is true that any article 
 that has come in immediate contact with the sick person, 
 as utensils, books, toys, and personal articles, should be dis- 
 infected at the end of the communicable disease. The 
 danger with continuing such a practice as terminal disin- 
 fection is that it places the emphasis in the wrong place and 
 
394 Healthful Living 
 
 makes people believe that the danger lies in the room and 
 its hangings. The danger lies in coming in contact with the 
 person having the disease and allowing that person to cough 
 or breathe in your face. Doctors and nurses generally es- 
 cape the communicable diseases because they are very care- 
 ful about washing their hands and protecting themselves from 
 coughs. We will not fear infections when we are intelligent 
 enough to avoid the real dangers and do not allow ourselves 
 to be deluded by a false security. 
 
 Antiseptics* There is a considerable interest to-day in 
 preventing disease and many people are impressed with the 
 large number of antiseptics on the market. Everything on 
 the market used by people in a personal way claims some 
 particular antiseptic feature. Tooth powders, shaving soap, 
 gargles, and numerous other articles claim this feature. 
 Now, the important thing for us to remember is that the 
 antiseptic day has passed and we are living in an age that is 
 emphasizing the aseptic feature in both sanitation and surgery. 
 Surgeons do not employ antiseptics as formerly in the care of 
 wounds ; they use aseptic measures and keep the wound 
 clean. It is true that badly infected war wounds are treated 
 to-day by a new and powerful antiseptic, known as the Carrel- 
 Dakin solution, but sanitarians to-day depend upon cleanli- 
 ness and isolation of the sick person, and pay scant attention 
 to antiseptics and disinfectants. The modern method in 
 housekeeping is to keep the house clean and avoid the spring 
 house cleaning; the modern method in disease prevention 
 is to keep the sick isolated from the well, to keep the sick 
 and the well clean, and not try to kill the germs after dirty 
 habits of living have allowed severe infections to occur. 
 
 A curious theory of disease. There is an artless theory, 
 common among unlettered people, which holds that disease 
 is a distinct thing, and that when God made the various 
 diseases, he made plants to grow, each of which contains the 
 infallible remedy for one of the diseases. Such persons when 
 
Bacteria and Disease 395 
 
 they are ill, and after various treatments remain ill, cherish 
 the firm conviction that if they could only find the right 
 remedy that is growing in some plant, somewhere in the 
 world, they would immediately be cured, without any at- 
 tention to hygiene and the conditions necessary to health 
 and its recovery. Patent medicine venders particularly 
 foster this idea, although each one illogically adds that his 
 medicine will cure all diseases indiscriminately. 
 
 This simple theory is opposed to all the facts. The poisons 
 in plants are waste products that the plant seeks to remove. 
 They are, therefore, found mostly in the parts of the plant 
 that will be shed, as the leaves, seeds, and bark. The poisons 
 serve meanwhile to protect the plant from animals. The 
 only animals (besides man) that will touch the tobacco plant 
 are the goat and the tobacco worm ; their bodies seem to 
 have become used to the poison. No sick cat eats night- 
 shade, no sick cow eats jimson weed. The very bitter or 
 repulsive taste of most poisons shows them to be unsuited 
 to the animal body. No child would drink a liquid con- 
 taining the bitter alkaloid,* caffeine,* unless it were in- 
 fluenced by the example of its elders, and the bitter taste 
 were disguised with milk and sugar. 
 
 HEALTH RULES FOR SCHOOL CHILDREN 
 
 (From Public Health News, State Department of Health, New 
 
 Jersey.) 
 
 The " DO " Rules, or What to Do to Prevent Disease 
 
 1. Keep away from houses where any one is sick with infantile 
 paralysis or other communicable disease. 
 
 2. Keep away from sick people and those who have been in 
 contact with sick people. 
 
 3. During an epidemic, keep away from crowds. 
 
 4. Destroy all discharges from the nose and mouth. 
 
396 Healthful Living 
 
 5. Always cover your mouth with a handkerchief when you 
 cough or sneeze. If you cannot get a handkerchief, use your hands 
 and then wash them at once. 
 
 6. Keep away from flies and keep flies away from you. Flies 
 carry germs on their feet and in their stomachs. 
 
 7. Wash your hands with soap and water upon rising in the 
 morning, before each meal, after each visit to the toilet, after 
 coughing or sneezing in the hand, and before going to bed. 
 
 8. Keep clean. Take a bath every day and. see that all cloth- 
 ing worn next to the skin is clean. 
 
 9. Kill all vermin such as bedbugs, roaches, and body lice. 
 
 10. Keep your books, your pencils, and your desk clean. 
 
 11. Eat plain, wholesome food, including plenty of milk and 
 vegetables. 
 
 12. Keep the milk clean, covered, and cold. 
 
 13. Protect all food from flies. 
 
 14. Wash all food that is to be eaten raw., 
 
 15. Keep down dust. Always sprinkle floors with sawdust, 
 old tea leaves, or bits of newspaper, which have been thoroughly 
 dampened, before sweeping. Never allow dry sweeping. 
 
 16. Brush your teeth daily, or better, twice a day. 
 
 The " DO NOT " Rules, or What to Avoid to Prevent Disease 
 
 1. Do not go near sick people or the houses where they live. 
 
 2. Do not go in crowds during an epidemic. 
 
 3. Do not kiss anybody on the mouth, and do not let any- 
 body kiss you on the mouth. 
 
 4. Do not cough or sneeze in anybody's face or over food. 
 
 5. Do not put your fingers or pencils in your mouth or nose. 
 
 6. Do not spit or blow your nose on the floor use a hand- 
 kerchief. 
 
 7. Do not bite the corners of your books. 
 
 8. Do not spit on your hands when you play ball. 
 
 9. Do not bite an apple, candy, or other food that some one 
 else has been eating. 
 
 10. Do not eat food that flies have walked over. 
 
 11. Do not eat with dirty hands wash them. 
 
 12. Do not eat with your fingers use a fork or spoon. 
 
 13. Do not handle foods that others are to eat unless your 
 hands are absolutely clean. 
 
 14. Do not eat foods that have been handled by unclean hands. 
 
Bacteria and Disease 397 
 
 15. Do not eat apples, pears, or other raw fruits from the market 
 until they are carefully washed. 
 
 16. Do not stir up the dust either at home or at school. 
 
 17. Do not drink out of a cup that other people have used. 
 
 18. Do not wipe on a towel used by any one else. 
 
 19. Do not lend your pencils or books to others. 
 
 20. Do not borrow books or pencils, but have your own and 
 keep them for your own use. 
 
 21. Do not trade chewing gum, candy, horns, or whistles. 
 
 22. Do not wipe your nose on your hand or sleeve use a 
 handkerchief. 
 
 23. Do not use a soiled handkerchief get a clean one. 
 
 24. Do not wet your finger on your tongue to turn the leaves 
 of a book. 
 
 25. Do not have dirty hands wash them. 
 
 GLOSSARY 
 
 Alkaloid. An organic base containing nitrogen, (a base is a 
 compound capable of uniting with an acid and forming a salt), 
 and having powerful poisonous effect upon the animal body. 
 Alkaloids are of vegetable origin. 
 
 Antibodies. Substances developed in the blood during the course 
 of a disease. They are the chemical factors in the immunity 
 conferred by the disease. 
 
 Antiseptic. Preventing fermentation and decomposition. Pre- 
 venting the growth of bacteria. 
 
 Antitoxin. A serum for the treatment of diphtheria. It is made 
 by injecting Bacillus diphtheria in a horse and after the horse 
 has developed the antibodies of immunity, the serum of the 
 blood of the horse is taken and certain graduated amounts 
 used in treating diphtheria in man. 
 
 Caffeine. An alkaloid found in coffee. 
 
 Caisson. A large water-tight box in which work is done below 
 the water level. The pressure of the air in a caisson is higher 
 than in ordinary atmosphere. 
 
 Cholera. An acute epidemic disease caused by the Bacillus of 
 Koch, a comma-shaped bacillus. 
 
 Contraindication. A sign or symptom indicating the inappro- 
 priateness of the procedure. 
 
 Dynamo. A machine driven by steam or some other force which 
 converts the energy of the machine into electrical energy in 
 the form of an electric current. 
 
Healthful Living 
 
 Fungus. A plant without chlorophyll that derives its nourish- 
 ment entirely from organic compounds. It will be remembered 
 that plants having chlorophyll obtain their nourishment by 
 using inorganic compounds. 
 
 Immunity. A condition developed in the body either actively 
 by the individual or passively by an operator. Active immunity 
 results in the course of a disease by the formation of anti- 
 bodies in the blood. Passive immunity is developed by in- 
 jecting into the blood an immune serum such as antitoxin, 
 or by such a process as vaccination. 
 
 Infection. A condition developed in the body by the entrance 
 of disease-producing organisms into the body. 
 
 La Grippe. An acute epidemic disease caused by the Bacillus 
 influenzce. It is easily communicable and should be avoided. 
 
 Larva. One of the forms of an animal after leaving the egg 
 form and before it appears like the parent. This type of de- 
 velopment is seen especially in insects. 
 
 Lockjaw. The popular name for a disease that shows by an early 
 affection of the jaw muscles. The disease, tetanus, is caused 
 by the Bacillus tetani. This organism is prevalent in soil 
 especially around barnyards and richly fertilized fields. 
 
 Microbe. A name sometimes used for bacterium or germ. 
 
 Mold. A fungous growth occurring in warm moist places and 
 seen especially on food, walls, and clothing. 
 
 Obesity. A condition of great fatness with accompanying un- 
 soundness. 
 
 Parasite. A living organism that lives on or in another, called 
 its host, from which the parasite derives its nourishment. 
 
 Pasteurize. To heat milk to a temperature from 150 to 155 F. 
 for twenty to thirty minutes, for the purpose of destroying 
 the bacteria of the milk. This method was originally proposed 
 by Pasteur, a great French scientist. 
 
 Plague. A pestilence or severe epidemic disease. In the middle 
 ages plagues were common. To-day they are less common 
 because we know the causes of them and how to combat their 
 spread. 
 
 Ptomaine. A poison developed in food by a process of fermenta- 
 tion and decomposition. 
 
 Quarantine. Preventing for a fixed period of time (originally 
 forty days, quadraginta, forty) communication with persons, 
 'ships, or goods arriving from ports infected with communi- 
 cable disease. 
 
Bacteria and Disease 399 
 
 Serum. The plasma of the blood is called the serum, but the 
 term is also used to designate the material used for immuniz- 
 ing purposes. Antitoxin is a serum and is made from the 
 plasma of a horse. 
 
 Sterilize. To make sterile, without life. By a process of heat 
 or chemicals to destroy all the bacterial life on an instrument, 
 gauze, etc. 
 
 Toxin. The poison developed by bacteria. 
 
 Tuberculin. A liquid prepared by growing Bacillus tuberculosis 
 in a broth culture. 
 
 Vaccination. A process of developing in man immunity to small- 
 pox by causing a mild form of the disease when the small- 
 pox virus is rubbed into a small opening in the skin of the arm 
 or leg. 
 
 Vaccine. A preparation of the weakened or the dead bodies of 
 bacilli used to inject into man for the purpose of developing 
 immunity to a particular disease. 
 
CHAPTER XX 
 THE EFFECT OF ALCOHOL AND TOBACCO 
 
 I. The Body as a Storehouse of Energy. 
 II. The Meaning of Fatigue. 
 
 III. The Effect of Stimulants on Energy and Nerves. 
 
 Artificial stimulants 
 Natural stimulants 
 
 IV. Alcohol. 
 
 As a food 
 As a poison 
 
 Summary of the effects of alcohol 
 V. Tobacco. 
 
 General effects of tobacco 
 
 The effects of tobacco upon youth 
 
 The body as a storehouse of energy. Succi, an Italian, 
 successfully accomplished a fast of fifty days in London, be- 
 ing constantly watched to make sure of his fasting. There 
 is reported, on good authority, a case of an insane person 
 who suddenly became possessed by the idea of taking no 
 food, and who lived, sixty days before starving to death. 
 Long fasts are a great injury to the body, no doubt, but 
 what can be learned from such experiences? Certainly it 
 shows the wisdom with which we are made and that our 
 physical organization is very provident. 
 
 Once some miners were shut in by caving of part of the 
 mine. But unlike the cases mentioned above they were 
 without water as well as food. When, by digging, the 
 rescuers reached them, seven days after, several were still 
 
 400 
 
The Effect of Alcohol and Tobacco 401 
 
 found alive, although most of them had succumbed. The 
 miners, no doubt, had nourishment in -their bodies for some 
 weeks more of life, but the necessary solvent in the form of 
 water was lacking to dissolve it and bring it within the reach 
 of the cells most needing it. 
 
 This fact concerning the amount of nourishment stored 
 in the human body (in one case a two months' supply !) is 
 one of the most stupendous facts with which the science of 
 physiology has to deal, and it should be borne in mind, or 
 we may greatly deceive ourselves about some very simple 
 matters. Did you ever get so tired that you had to give up 
 and stop, however much you would have liked to continue 
 at work or play? To rest was the wise thing to do. Now, 
 although you learn from physiology how much energy you 
 have stored up within your frame, you should not on that 
 account, be tempted to go on until you almost break down. 
 Probably you know people who are conceited about their 
 bodies and say they are made of cast iron ; nothing can hurt 
 them. Did you ever know anybody who was conceited 
 about his mind and thought he was very bright? It is just 
 as foolish to be conceited about the body. It is a very wise 
 arrangement that under ordinary conditions we cannot get 
 at the surplus energy we have. We are compelled to be 
 provident, as it were ; yet stimulants and narcotics, by irri- 
 tating the cells, will cause them to expend some of this re- 
 serve energy ; they will enable man to get at this precious 
 store which he should save for emergencies, such as a period 
 of sickness when he cannot digest food, or some time when he 
 is making some mighty effort. This reserve energy will 
 enable him to undergo some trying ordeal successfully. Did 
 you ever know of a weak, sick man who had eaten very little 
 for weeks, yet was so powerful that it took several strong 
 men to hold him? This sometimes happens in the case of 
 sick men who are delirious and crazed with pain and with the 
 poisons formed in their bodies during illness. 
 
 2D 
 
402 Healthful Living 
 
 The meaning of fatigue. Suppose you are tired or worked 
 out. The fatigue depresses you, and you feel discouraged. 
 What ought you to do? Why, rest, of course, and you will 
 soon feel all right again. This seems very simple, yet some 
 people will not do this way, but take an alcoholic beverage 
 or tobacco, which will keep them from feeling tired when 
 they are tired. If you have been working hard preparing 
 for examinations, or gathering hay, or attending to some 
 important business, or have been under the excitement of 
 some pleasure trip, and feel blue and worn out, then bear 
 the result like a man, or like a true boy or girl, as the case 
 may be. Giving up for a while, or " toughing it out " with 
 the blues, or losing a little time from business, will not hurt 
 you but will make you strong, while a stimulant would leave 
 you less of a man than before. 
 
 There is only one source of energy for man's body, and 
 that is the union of food and oxygen. He must get his 
 energy from the same source that the engine does, and that 
 is from his food, which serves as fuel, and the oxygen that 
 burns it. The millions of little workers, the cells, will store 
 up food within themselves and get rid of the ashes and refuse, 
 and the pure, sound body will be ready for work again. 
 
 The effect of stimulants on energy and nerves. Artificial 
 stimulants. You remember those wonderful little one- 
 celled animals, the amcebas. If poison is brought near, they 
 will try to escape it. They also throw out the impurities 
 generated by their own life processes. If anything touches 
 one roughly, it will draw back from the danger. Likewise, 
 if a man takes poison, such as alcohol or tobacco, into his 
 body, the cells will try to throw it off. The heart, although 
 it may be already tired, goes to thumping anew, secretions 
 are poured out by the cells to dilute and weaken the poison, 
 and the great activity excited diverts the man from noticing 
 his fatigue, and makes him think the poison has given him 
 renewed strength. It is the same as if he, thought the whip 
 
The Effect of Alcohol and Tobacco 403 
 
 instead of the oats gave the horse strength. The horse, 
 like the cells of the body, is only trying to avoid something 
 harmful, and like them, he uses up his strength in so doing. 
 After a while he will be very stiff and tired. There is no 
 artificial stimulant that does not cause a reaction. The 
 stronger the stimulant, the worse the poison. Strychnin* 
 is one of the deadliest poisons known, and also one of the 
 most powerful stimulants. If an animal is given strych- 
 nin, its nerve tissue is sometimes reduced to such an irri- 
 table condition that a loud sound, or merely touching any 
 part of it, will throw every muscle of its body into a spasm. 
 
 Some people are coffee topers and tea topers. It is a mis- 
 take to say these drinks quiet the nerves. Who is so nervous 
 as the old lady who drinks frequent cups of tea to quiet her 
 nerves? It is the tea that is making her nerves unsteady. 
 Some people unaccustomed to tea will lie awake most of the 
 night, wearing out their energies by sleeplessness if they 
 drink only one cup of it. 
 
 It is easy to understand how a person sitting up with a 
 friend who is dangerously ill will take tea or coffee to keep 
 him wide awake. If he has some great duty to perform, or 
 trust imposed upon him that will soon be over, there may 
 possibly be some reason in stimulating his activities, even if 
 he must suffer reaction and depression thereafter. But why 
 one will habitually disturb his body with narcotics, such as 
 alcohol, tobacco, or even mild narcotics, such as tea and 
 coffee, so as always to keep his vital force and reserve energy 
 at a low ebb, is difficult to understand. It can only be ex- 
 plained by ignorance of the fundamental laws of his being. 
 
 Natural stimulants. The chief natural- stimulants are 
 cold air, sunlight, pure air, physical exercise, interest, joy, 
 and other wholesome emotions. A deep breath of pure air 
 is a better stimulant than a glass of beer ; climbing a hill or 
 sawing a log of wood will make the blood flow faster than 
 an alcoholic drink will ; a pleasant talk with a friend is a 
 
404 Healthful Living 
 
 better sedative* than a cigar; a cold day will steady the 
 nerves better than an opiate* ; a trust that a good Power 
 rules over all will drive away worry quicker than cocaine ; 
 a cold bath will bring steadier nerves than coffee ; 'a cold 
 wind will give a better appetite than food soured with 
 vinegar or hot with pepper. Natural stimulants do not 
 produce a reaction because they do not excite the body to 
 an injurious degree, nor cause the energies to be consumed 
 beyond the danger point. Persons who go through life under 
 the stimulus of these natural blessings have sound steady 
 nerves and clear brains. They do not have to take anything 
 " to quiet their nerves." 
 
 Man's body was beneficently designed to keep a large 
 amount of energy stored up, so that he can feel conscious 
 of his power and go through life buoyantly and happily, 
 and prepared for all emergencies, the highest being in 
 the world that he inhabits. He is in a world full of interest. 
 Delicious fruits and nutritious nuts and grains abound to 
 awaken and satisfy his appetite. The bright sun not only 
 shines upon his skin, but deep into it, and stimulates the 
 cells; the fresh breezes striking his nerves, start currents 
 coursing through his body. The oxygen penetrates to every 
 cell, purifying and awakening to life. The pleasure of as- 
 sociation with his fellow-creatures, and various other pleas- 
 ures, arouse him to do his part in the world. There is no 
 need to seek in the jungle for some bitter berry, or among 
 the weeds for some nauseating leaf, or among decaying apples 
 or grapes or fermenting grain for a burning and revolting 
 liquid in order to stir his being to action. He lives the life 
 for which his body was designed. 
 
 Alcohol. In 1914, during the progress of the Great War, 
 Russia prohibited the manufacture and sale of vodka, the 
 alcoholic drink in general use in Russia before that time. 
 The effect upon the people of this forced abstinence was re- 
 markable. Savings banks sprung up in every village where 
 
The Effect of Alcohol and Tobacco 405 
 
 before poverty was predominant ; efficiency in all phases of 
 Russian life increased; and the nation by this act alone 
 played a more important part in the war than would ha,ve 
 been possible otherwise. The question, " Is alcohol a food ?" 
 was answered by the Russian in terms of greater national 
 efficiency by the removal of alcohol from the diet. 
 
 After a rapid increase in prohibition in the United States, 
 Congress in 1917 passed an amendment to the Constitution 
 submitting the question of national prohibition to the state 
 legislatures. By 1919, forty-five state legislatures had rati- 
 fied the amendment. The most important argument for 
 national prohibition has been the argument to conserve the 
 food of the country, because in the manufacture of alcohol es- 
 sential grains of the food supply are used in large quantities. 
 There has been, also, an increasing appreciation of the loss in 
 efficiency in those who use beer and whisky, and with the 
 whole nation training to become efficient, the use of alcohol 
 has been cast aside as an unnecessary incubus. 
 
 There are some people, however, who believe that alcohol 
 is a food. They seek to justify its use on this ground. 
 
 Alcohol as a food. When alcohol is taken, about ninety- 
 five per cent of it is oxidized and changed into carbon dioxide 
 and water. This was found out many years ago and raised 
 the question as to whether it should be classed as a food. 
 Investigations were made, and the result was that alcohol 
 was classed with the poisons and not as a food. The ques- 
 tion has been reopened several times in the last half-century, 
 but always with the same result. Scientific men generally 
 continue to classify it as a poison and not as a food. Mor- 
 phine, mushroom poison, strychnin, and other dangerous 
 poisons are oxidized in the body and yield up their energy, 
 yet they are recognized as poisons. A substance cannot be 
 classified as a food simply because it is oxidized in the 
 body. 
 
 Leading scientists define a food as a substance of such a 
 
406 Healthful Living 
 
 nature that, when absorbed into the blood, it nourishes the 
 body without injuring it. 
 
 Sugar is a food, but a solution of sugar can undergo a change 
 caused by the growth of millions of yeast plants and the food 
 is lost. The change is called fermentation, and alcohol is 
 one of the poisonous products of this process of decay or 
 fermentation. 
 
 The condition of the body after it has oxidized alcohol 
 is quite different from its condition after it has oxidized 
 sugar or bread. Benzine* is very easily oxidized. If poured 
 upon the fire of a locomotive, it would make the water boil 
 so rapidly that there would be danger of straining or bursting 
 the boiler. It would burn so rapidly as almost to make an 
 explosion, and a very large part of the heat caused by the 
 oxidation would be lost. A stove needs a slower burning 
 substance than gunpowder or benzine. A locomotive needs 
 a slow-burning fuel which will develop heat at such a rate 
 that it will be possible to utilize it. The body needs even 
 slower burning substances than the locomotive, sugar, starch, 
 and fat; not a more rapidly burning substance, such as 
 alcohol, which in burning will weaken the tissues and shock 
 and injure the delicate cells of the one who drinks it. In the 
 chapter on the blood it was learned that alcohol does not 
 even cause a gain of heat in the end, since the paralysis of 
 the capillaries resulting from a drink causes the warmth to 
 be taken to the surface and escape, so that the body is cooler 
 than before the drink. 
 
 True food does not burn in the blood ; it is stored in the 
 cells in the form of very unstable compounds. These com- 
 pounds break down under the stimulus of oxygen and the 
 nerve impulse, and set free energy. The cells of the nerves 
 and muscles correspond to the furnace and steam chest of 
 the engine. Suppose, instead of pouring benzine into the 
 furnace, you burned it in the cab or the smokestack. Do 
 you think it would increase the power of the locomotive? 
 
The Effect of Alcohol and Tobacco 407 
 
 Alcohol is not stored in the cells, nor does it enter into com- 
 bination to form the energy compound, the breaking down 
 of which sets free the energy stored up. Alcohol burns 
 quickly after entering the body ; a large part of it, indeed, 
 never gets beyond the liver, and is burnt in this long-suffer- 
 ing organ. But some of it gets into the general circulation, 
 and is distributed throughout the body, irritating the nerve 
 cells and poisoning them and every other tissue. 
 
 Alcohol may not be considered a food, therefore, because 
 it is not a tissue builder, as are the proteins, and it is not 
 stored in the body, as are the fats. In addition, since it has 
 a toxic action, it injures the body when taken in excess. 
 This may be the case with other foods, but they give warn- 
 ing when taken in excess. Alcohol as a food is exceedingly 
 expensive. Dr. Woods Hutchinson has said, " as a food, 
 alcohol is a joke and a bad joke at that." 
 
 Dr. D. B. Armstrong gives the following figures in tabular 
 form to indicate just how expensive alcohol as a food would 
 be (food is useful to the body primarily as it gives energy, 
 and its power to produce energy is dependent upon its caloric 
 value) . 
 
 APPROXIMATE FOOD VALUE FOR TEN CENTS 
 
 CALORIES FOB 
 ARTICLE TEN CENTS 
 
 Sherry 30 
 
 Beer 240 
 
 Sirloin Steak 375 
 
 Eggs 450 
 
 Bread . 2180 
 
 Corn meal 3310 
 
 Oatmeal 3720 
 
 Alcohol as a poison. C. F. Hodge, Professor of Physi- 
 ology in Clark University, made a series of experiments upon 
 four kittens and four spaniels. Moderate non-intoxicant 
 doses of alcohol were given daily to two of each. The purring 
 
408 Healthful Living 
 
 and playfulness of the kittens dosed with alcohol gradually 
 disappeared. At the end of ten days, they took severe 
 colds. They were dwarfed in growth to 59, 63, and 39 per 
 cent, respectively, as compared with the others. Of the 
 two pairs of spaniels, the pair treated with alcohol weighed 
 less, and developed only 71 and 57 per cent of the activity 
 of the other pair, as shown by the pedometer. The dogs 
 treated with alcohol also developed strange symptoms of 
 timidity and fear, suggesting the terrible fears of delirium 
 tremens and alcoholic insanity. 
 
 Decreased Physical Efficiency. In Dr. Hodge's opinion 
 the experiments above described have direct bearing on the 
 question of the effect of alcohol on the human system. The 
 experiments proved that alcohol causes depression of activity. 
 For man the highest aim is to develop useful activity, the 
 will, the determination to do as much of the world's necessary 
 work as he is capable of doing, and to maintain a sound, 
 vigorous body to enable him to carry out such determina- 
 tion. It is of the utmost importance, therefore, that we 
 understand the conditions of our physical systems under 
 which this great end can best be attained. 
 
 General Wolseley, of the British Army, found on experi- 
 ment that those who did not receive alcohol were " fresher, 
 livelier, and marched better than those that had alcohol." 
 An experiment on typesetters in Germany showed that those 
 who drank daily three fourths of a tumbler of wine were much 
 less efficient than abstainers. Their work decreased on an 
 average of 9 per cent. This means not only that the man 
 could not do as much work, but also that his earning power 
 would be less. On pages 46 and 323 it was shown how 
 alcohol affected mountain climbing and marksmanship. 
 
 Decreased Mental Activity. Memory is a very valuable 
 quality of mind, and a good memory is not to be lost without 
 regret. Dr. Smith showed in experiments that 70 per cent 
 less work in memorizing figures was done when using alcohol 
 
The Effect 0} Alcohol and Tobacco 
 
 409 
 
 (Fig. 227). Professor Vogt showed in many experiments 
 that the taking of one to three glasses of beer interfered 
 with the memory process ; that it took on the average 18 per 
 cent longer to learn lines of poetry. In Italy, where a great 
 
 V/////A Ab 
 
 Effect of Alcohol on Memorizing 
 
 FIG. 227. Height of columns represents the number of figures learned 
 each day. Increase from day to day on abstinent days shows the gains 
 made by practice. Decrease of fifth and sixth days due to temporary ill- 
 ness, and on the sixth day one dose of alcohol was taken. Dotted line from 
 fourth to twenty-fifth days shows the normal rate of increase. Alcohol 
 about equal to that in from two to four glasses of beer (40.80 grms.) taken 
 on the alcohol days. Memorizing done eight or ten hours after taking the 
 alcohol. Amount of work done on the twelfth alcohol day about 70 per 
 cent less than it should have been, and was less even than was done on Day 
 one. 
 
 deal of wine is made, it was found that the use of alcohol 
 in this form even interfered with mental work in school. 
 The following shows the report on 4000 children : 
 
 
 462 
 
 ABSTAINERS 
 
 1616 
 DRINK WINE 
 OCCASIONALLY 
 
 2021 
 DRINK WINE 
 DAILY 
 
 
 Per Cent 
 42.56 
 
 Per Cent 
 30.5 
 
 Per Cent 
 29.8 
 
 Fair 
 
 53.49 
 
 41.8 
 
 39.7 
 
 Poor 
 
 3 85 
 
 27 
 
 303 
 
 
 
 
 
 Now alcohol renders the user liable to make mistakes. 
 Consequently the managers of the Lackawanna Railroad, 
 
4io 
 
 Healthful Living 
 
 after an accident caused by the engineer going past signals, 
 made the following rule : " Trainmen must not drink or 
 enter saloons even when off duty." This engineer had been 
 drinking and the accident cost the death of 40 people and 
 serious injury to 75 more. 
 
 Drink also causes more accidents to the worker himself. 
 Hence, employers are demanding that workers shall not use 
 alcohol. The following chart (Fig. 228) shows how difficult 
 
 Employers Who Prefer Non-Alcoholized Workmen 
 
 from f/>e Report by the US.DFPAffrMFNr OF LABOR of an investigation authorized by Conyress,/897. 
 \ I Represents employers who do consider en app/icant's drink/ny habits . 
 K\\\\\\\\VJ Represents employers who do not consider an applicant's drinking habits. 
 77% of A// Establishments Reporting 
 
 56.5% of Mines and Quarry-men ^^^^^^ 
 
 72% of Agricu/lur/sts 
 79% of Manufacturers 
 
 88% of Trades 
 
 E 
 
 V% of Transportation 
 
 FIG. 228. Drinkers are not sought as workmen or for responsible 
 positions. 
 
 it is for the drinking man to obtain employment. It is 
 harder for him to hold it, if he gets it, because he is less 
 efficient, more liable to injury, and often causes trouble 
 among other employees. 
 
 It is significant that great industrial organizations, rail- 
 roads, and mercantile houses are requiring that their men do 
 not drink. They know that alcohol in any form lowers the 
 efficiency of their men and the men are beginning to realize 
 that they are more capable and advance more rapidly if they 
 leave drink alone. George Patullo writing in the Saturday 
 Evening Post of the encampment of the National Guard on 
 the Mexican Border says, " It is growing to be the same with 
 the soldier as with every other calling. He finds that booze 
 
The Effect of Alcohol and Tobacco 
 
 411 
 
 does not pay, that it is a losing game and hurts his health. 
 He has discovered that commanders frown on it and people 
 with whom he would like to associate are temperate and 
 prone to shy off from a hard drinker." 
 
 Insanity. The sober man thinks first and then acts ; 
 the man under the influence of alcohol acts first and thinks 
 afterward. Alcohol so interferes with the working of the 
 mind (Figs. 229, 230) that the man is unable to make correct 
 judgments. Consequently 
 after a time his mind is really 
 impaired. In the State of 
 New York over 25 per cent 
 of the insane in the hospitals 
 of the state are insane be- 
 cause of the use of alcohol. 
 It is estimated that there is 
 lost to the State of New York 
 every year, through insanity, 
 over $2,400,000 and to the 
 United States $12,000,000. 
 The report of the states in 
 which alcohol is not allowed 
 shows a decrease in the in- 
 sanity of that state. For 
 example, the State of Kansas 
 has made great improvement 
 in this regard. 
 
 Now at one time it was thought right and proper to drink, 
 and in some places to-day drinking is a custom, a tradition 
 that is followed. There are parents who drink alcoholic 
 liquors because they formed the habit in their youth when 
 drinking was considered less harmful than it is known to be 
 to-day. The one test of growth, in a people, is to make im- 
 provements from one generation to another. So the child is 
 not to judge the parent either as regards action or motive. 
 
 FIG. 229. This figure shows four 
 nerve cells from the brain of a man 
 who died of alcoholic insanity. It 
 will be noticed that the body of the 
 cells and the nerve fibers are broken 
 up and degenerated. 
 
 The changes shown in Fig. 230 are 
 the more severe changes, and repre- 
 sent complete destruction of the 
 nerve tissue. 
 
412 
 
 Healthful Living 
 
 The new generation, better acquainted with the facts, many 
 of them discovered recently, must see that it takes advantage 
 
 of the facts and does 
 not repeat the mis- 
 takes of the older 
 generation. In this 
 way civilization, in 
 which we all have a 
 part to play, will 
 advance. 
 
 Summary of the 
 effects of alcohol. 
 In conclusion on this 
 question it may be 
 stated that the fol- 
 lowing represents the 
 results of alcoholic 
 drinks as a beverage : 
 
 1. Alcohol tends 
 to reduce physical 
 strength and endur- 
 ance and the amount 
 of work done. 
 
 2. It impairs men- 
 tal work. 
 
 3. Alcohol belongs 
 to the class of habit- 
 forming drugs, like 
 opium and morphine, 
 which tend to create 
 a craving for increas- 
 ing amounts. In certain persons this leads inevitably to 
 heavy drinking and its serious consequences. 
 
 4. The alcohol user on the average is especially liable to 
 sickness and to premature death. 
 
 FIG. 230. An illustration of the nerve 
 branches and fibers in a case of alcoholic in- 
 sanity. The patient died of this disease, and 
 when the nerve fibers were examined under the 
 microscope, they were shown to be swollen and 
 broken down in the manner illustrated in the 
 drawing. The swellings of the nerve fibers, as 
 seen in this illustration, are characteristic, 
 and are usually seen in the brain of those 
 dying from alcoholic insanity. 
 
The Effect of Alcohol and Tobacco 413 
 
 5. Drink increases liability to accident even in the person 
 who is never intoxicated. 
 
 6. The use of alcohol by parents is often responsible for 
 a high death rate in children, or for physical or mental defects. 
 
 7. Alcoholism does not necessarily mean drunkenness. 
 The habitual user of alcohol may show some of its effects 
 without ever reaching the stage of intoxication. 
 
 8. Alcohol is not a stimulant to the nervous system, but 
 a depressant.* 
 
 9. Because of the effect of alcohol on mind and body it 
 is responsible directly and indirectly in the United States 
 for at least one fourth to one half of all poverty and neglect, 
 for more than one third of pauperism, for one fifth of the 
 insanity and divorces, and one half of the crime. 
 
 Tobacco. The leaf of the tobacco plant is used for smok- 
 ing and chewing. At one time it was used in powdered 
 form as snuff. There are many reasons why tobacco should 
 not be used by man, and no satisfactory reason why it should 
 be used. With this viewpoint in the foreground there are 
 some people who say that a person who uses tobacco is a 
 fool and that he will go insane if he smokes cigarettes. Now 
 such a statement is at variance with the facts. In con- 
 demning or praising any method or practice, care should be 
 exercised in forming a judgment and discretion used in stat- 
 ing a belief. What does tobacco do to the cells of the body ? 
 How does it injure them ? What may be the loss in terms 
 of efficiency? These are questions that we should be pre- 
 pared to answer. 
 
 General effects of tobacco. In the first place we can think 
 of men who are strong physically, keen mentally, and sound 
 morally, who at times use tobacco. If they use it moderately, 
 they may reply to our question by saying, " smoking does 
 not hurt me." By such a statement one may mean that no 
 perceptible harm is felt. But, how much keener mentally, 
 how much stronger physically, would he be, if he did not smoke. 
 
414 Healthful Living 
 
 Smoking contributes nothing to a man. Men smoke but 
 the smoking is not a characteristic of manliness. So, be- 
 cause you know men who smoke, do not think that smoking 
 does not hurt them. Think rather of how much better in 
 every way they would be if they did not smoke. 
 
 It is true that the use of tobacco forms a habit that tends 
 to increase the amount of tobacco used. This is the special 
 danger in cigarette smoking. It leads frequently to the use 
 of so many cigarettes that health and strength are lost. 
 
 That smoking causes undesirable effect upon the body is 
 shown in the custom of college athletes. Coachers and 
 trainers do not permit smoking by those who play on the 
 team and all athletes who seek to excel in sport, do not use 
 tobacco. 
 
 We know that smoking impairs one's physical efficiency. 
 A war correspondent visiting the Italian trenches in the 
 Trentino during the recent war writes as follows : 
 
 "As we pushed on, all our old sins of pipes and cigarettes 
 began to be expiated in our middle-aged hearts. ... So 
 we struggled on, the easy perspiration bathing our bodies. 
 Hiatt was doing better than I, being younger and less guilty 
 of cigarettes. I would force myself until I could go no 
 farther ; would stop ; would droop over my alpen-stock and 
 pant like a netted fish." 
 
 Men who smoke to excess find that they become nervous, 
 lose their appetite for wholesome food, and show a distinct 
 loss in efficiency. 
 
 The effects of tobacco upon youth. The youth who looks 
 forward to physical efficiency as well as mental efficiency 
 as important factors in doing a work and achieving a place 
 in the world, will leave tobacco alone. The growing boy 
 suffers the most of all from the use of tobacco. His growth 
 is interfered with, his heart is injured, and his stomach dis- 
 turbed. If the boy thinks he wants to smoke, he should 
 wait until he is twenty-five years old ; then with developed 
 
The Effect of Alcohol and Tobacco 415 
 
 body and a wiser mind, if the use of tobacco seems desirable, 
 let him make the choice, cognizant of its dangers and limita- 
 tions. The youth who looks forward to excellence in athletics, 
 to achievement in business or the professions, to authority and 
 control in store and factory, will select his habits as carefully 
 as his friends, his food as carefully as his facts, and he will 
 leave tobacco out of the things that are for him. 
 
 APPLIED PHYSIOLOGY 
 
 1. Should a person with a " cold " keep away from other 
 people ? 
 
 2. What is the value of vaccination ? Are you vaccinated ? 
 
 3. Do you take reasonable care to see that your food is fresh ? 
 Is this important ? Can ill health result from decayed food ? 
 
 4. What diseases may flies carry? How is your home pro- 
 tected against flies? 
 
 5. How many hours a night do you sleep ? Does it satisfy the 
 requirement ? What is the requirement for your age ? 
 
 6. Do you wash your hands before eating? In what diseases 
 is this habit very important ? 
 
 7. Do you sleep at night with your windows open ? In winter? 
 
 8. Do you attend to the elimination of the body waste every 
 day ? How important a habit is this ? 
 
 9. Are bacteria destroyed within the body? 
 
 10. Which is the most important, prevention of infection, or 
 disinfection after infection has resulted from carelessness ? 
 
 11. Is cleanliness of value in the home? How much more 
 valuable is it in the person ? 
 
 12. How many Health Rules for Children do you know and 
 follow? 
 
 13. Is alcohol a food? How did the Russian government solve 
 the question? 
 
 14. What is fatigue? How can you tell when it is time to rest? 
 
 15. Are stimulants advisable when you are tired? What will 
 rest do that stimulants will not do ? Is restoration of more value 
 than stimulation? 
 
 16. What is the difference between natural and artificial 
 stimulants ? 
 
 17. Write an essay on alcohol with reference to its impairment 
 of the efficiency of the body. 
 
4i 6 Healthful Living 
 
 GLOSSARY 
 
 Benzine. A colorless and highly inflammable liquid obtained 
 
 from crude oil by distillation. 
 Depressant. A substance that lowers the irritability of the body 
 
 cells, and makes it difficult for them to respond. 
 Opiate. A substance allied to opium and capable of inducing 
 
 sleep. 
 Sedative. A medicine having the power to quiet and sooth the 
 
 body. 
 Strychnin. A white crystalline poisonous compound with the 
 
 formula (C 2 iH 2 2N 2 02). It is a strong stimulant of the nervous 
 
 system and highly poisonous. 
 
APPENDIX 
 FIRST AID IN EMERGENCIES 
 
 Artificial respiration. This is a means for getting air 
 into the lungs of a person after drowning, smothering, gas 
 poisoning, and the like. It is a rather simple procedure and 
 not so complicated as a young friend of the author seemed 
 to think when she called it " agricultural perspiration." It 
 is performed in the following way (Schaefer Method). 
 Place the subject face downward on the ground, turn the 
 face to one side, and bring the hands to a resting place beside 
 the face. Kneel astride the body of the person and place 
 your hands on each side of the back in the region of the lower 
 ribs. You are now ready to begin. It must be remembered 
 that the average rate of respiration is about 18 times a 
 minute and the procedure you are to follow should proceed 
 at about the same rate. (1) Lean forward on your hands 
 so that all your weight may be brought to bear on the ribs 
 of the subject. This forces the air out of the chest. (2) Raise 
 your body and release the pressure on the ribs. The elastic 
 chest wall will fill out and take in air. This pressure and 
 release at the rate of 18 times a minute will cause the air to 
 pass in and out of the lungs and so will provide for the neces- 
 sary oxygen. 
 
 Inasmuch as the most frequent cause for the use of artificial 
 respiration comes from drowning, it is important to know 
 and remember the proper care regarding accidents on the 
 water. If the boat or canoe upsets, the first efforts should 
 be directed to getting hold of the side of the upturned ves- 
 sel. A boat or canoe will float and will support the weight 
 2E 417 
 
418 Appendix 
 
 of several persons. After support is obtained, then one 
 may look around to see what is the desirable thing to do. 
 In many cases other people will see you and come to your 
 assistance. Their assistance is often too late if the one 
 having the accident has thrown himself around in the 
 water, has called out, and has taken a lot of water into the 
 mouth causing choking and making breathing difficult. Do 
 not cry out as the boat upsets, for you are liable to choke 
 with water taken in with the mouth open. 
 
 Black eye. A blow in the face, by bruising the soft 
 tissues around the eye, may cause discoloration. The best 
 treatment is the immediate application of an ice pack 
 (chipped ice in an ice bag) or cold compresses applied every 
 half hour. If this does not entirely prevent the discoloration, 
 the part may be painted by a face paint but usually this is 
 unnecessary. Beefsteak serves no valuable purpose in this 
 injury when applied to the part. 
 
 Burns. Burns are of different degrees of severity de- 
 pending upon extent of the burn in area and in depth. The 
 depth of the burn is described as follows : The first degree 
 shows a reddening of the cells of the epidermis ; the second 
 degree shows a separation of the epidermis from the dermis, 
 with the formation of serum between the two layers (blister) ; 
 the third degree shows the destruction of the epidermis with 
 some burning and injury in the dermis. 
 
 After the burn, be it from heat, chemical, or other source, 
 do not touch the part burned with the fingers, do not apply 
 salve of any kind, and do not open any blisters. The best 
 first-aid dressing is the application of the following on a 
 sterile gauze dressing : 
 
 Picric acid 65 grains 
 
 Alcohol 2.5 ounces 
 
 Distilled or sterile water 1 quart 
 
 This solution is made by dissolving the picric acid in the 
 alcohol and then adding the water. Do not remove the 
 
Appendix 
 
 419 
 
 dressing for three days if the above precautions have been 
 taken. If, however, the above dressing is not available, bak- 
 ing soda may be applied directly to the burn and the wound 
 then covered with a sterile bandage. On about the third day, 
 blisters may be opened with a needle after its tip has been 
 heated in a flame to a red heat (a match may be used for 
 this purpose). Burns which do not blister are not danger- 
 ous and they may be treated by applying sterile vaseline. 
 
 Broken bones. A broken bone is a fracture of the bone. 
 In case of such acci- 
 dent keep the patient 
 quiet. If he must 
 be moved, a splint 
 for the part may be 
 made by means of a 
 shingle, umbrella, 
 pillow, or folded 
 newspaper. Send for 
 the doctor. If the 
 end of the bone pro- 
 jects through the 
 flesh, do not touch 
 the wound but cover 
 it with a sterile 
 bandage. 
 
 Cuts and wounds. 
 -Keep the cut or 
 wound clean (Fig. 
 231). This does not 
 mean putting some 
 so-called antiseptic 
 on it to clean it, but 
 it means in most 
 cases putting nothing FlQ 231 I Boy gcouts giving first aid 
 
 On it but a Sterile treatment to a comrade. 
 
420 
 
 Appendix 
 
 dressing. If there is dirt in the cut, painting the area 
 with tincture of iodin will be good treatment. Hydrogen 
 peroxide and other first-aid remedies are less valuable. 
 Protect the wound from anything that will infect it as fingers, 
 clothing, or other objects, and help it to heal by keeping the 
 part at rest. If the wound bleeds severely and the blood 
 does not clot, pressure (see hemorrhage) may be applied 
 above the wound (Fig. 232). 
 
 If the wound does not bleed freely, as in the case of pin 
 pricks, injuries from nails and other sharp instruments, 
 
 every effort at first should be 
 directed toward causing free 
 bleeding. Tincture of iodin on 
 the end of a tooth pick wrapped 
 with a small amount of cotton, 
 should then be inserted in the 
 wound. If this treatment does 
 not effect a cure in one day a 
 surgeon should be consulted. 
 
 Fainting. The practice of 
 throwing a bucket of cold water 
 on the person who faints is not 
 to be approved. If the person 
 is reclining, let him lie and keep 
 the head lower than the feet. 
 Loosen all tight clothing and 
 
 gently fan the person or bathe the brow with cold water. 
 Never give whisky to a fainting person. Keep people away, 
 allow plenty of air, and maintain quiet. After the attack, 
 do not move the person for at least half an hour. 
 
 Foreign body in the eye. Cinders or dust particles in 
 the eye are best removed with the tip of a handkerchief. If 
 the object is on the upper lid, the lid must first be everted. 
 This is best done by asking the person to look down at 
 the time you are folding the lid back over a pencil. 
 
 FIG. 232. The method of 
 applying the knotted handker- 
 chief to compress a divided 
 artery, a, 6, track of the inner 
 artery of the left arm. 
 
Appendix 
 
 421 
 
 In many cases it is necessary to have the services of a 
 physician. 
 
 Foreign body in the ear. In removing objects from the 
 ear, care must be taken not to put any instrument in the ear. 
 Children sometimes put such things as peas, grains of corn, 
 etc., in the ear. They can be removed by washing out with 
 an oil; do not use water because that will make the grain 
 swell. Insects should be killed by oil and then they can 
 easily be washed out. 
 
 Hemorrhage. Hemorrhage is bleeding from a part, but 
 this term is not used in the case of simple cuts. Where the 
 flow is marked, the term 
 hemorrhage is more aptly 
 applied. In nose bleeding 
 from an injury, keep quiet 
 and compress the nostrils, 
 breathing through the mouth. 
 Often the nose bleeds from 
 picking the nose with the 
 finger nail. It is important 
 not to pick the nose in such 
 manner, and such bleeding 
 usually comes from an ulcer 
 caused in this way. Such an 
 ulcer may need to be cauter- 
 ized by a physician. 
 
 Bleeding from the lungs 
 gives frothy blood. Do not be alarmed but keep the patient 
 absolutely quiet. Send for the doctor. 
 
 Bleeding from the stomach usually shows in vomiting 
 and the blood has a black appearance like " coffee grounds." 
 Send for the doctor. 
 
 Bleeding from the bowels occurs usually in case of piles. 
 Keep quiet, avoid cathartics, and consult the doctor. 
 
 Bleeding from other parts of the body following an accident 
 
 FIG. 233. a, b, the track of the 
 right femoral artery ; the compress 
 applied near the groin. 
 
422 Appendix 
 
 is best controlled by applying with pressure a pad of sterile 
 gauze and holding it in place with a bandage. If this fails, 
 pressure above the bleeding point may be performed but 
 in most cases this is unnecessary. The application of such 
 pressure is to be made over the artery going to the part and 
 by means of a handkerchief loosely tied around the part 
 and then twisted tightly with a stick (Figs. 232, 233). 
 
 Sprains. The spraining of a joint is due to a twist or fall. 
 If the injury is cared for at once the best treatment is to 
 immerse the part in ice-cold water and keep it there for fifteen 
 minutes. If the injury cannot be cared for at once, the sub- 
 sequent treatment is the application of heat in the form of 
 hot water. In either case, afterwards the part should be 
 strapped properly and the patient allowed to use the part. 
 Bad sprains should be treated by a physician because there 
 is often a break in one of the bones entering into the forma- 
 tion of the ankle joint. 
 
 Poisoning. The elaborate tables of the common poisons 
 with their symptoms, antidotes, and treatment are of little 
 use because they are too long and difficult to memorize and 
 they are not available, as a rule, when most needed. The 
 principle may be taken as a general rule : if the poison is 
 an irritant that destroys tissues such as acids, lyes, metallic 
 poisons, etc., give to the patient the raw whites of several 
 eggs. First, however, send for the doctor. If the poison 
 is of another kind, a narcotic, such as chloral, alcohol, cocain, 
 laudanum, then make the patient vomit. Vomiting may be 
 caused by giving a teaspoonful of mustard in a glass of warm 
 water. This may be supplemented by more warm water 
 and by tickling the back part of the throat with the finger. 
 
 In poisoning, there is always depression of the vital powers, 
 so keep the patient quiet, apply heat externally, and, if neces- 
 sary, give artificial respiration. External heat may be pro- 
 vided by blankets, hot water bottles, or heated stones 
 applied to the body. 
 
Appendix 
 
 423 
 
 FIRST-AID REMEDIES TO HAVE IN THE HOME 
 
 Sterile gauze 
 
 Bandages of one and one half inch 
 
 Alcohol (grain) 
 
 Tincture of iodin 
 
 Adhesive plaster, one inch wide 
 
 Powdered boric acid 
 
 Aromatic spirits of ammonia 
 
 Picric acid for making the solution for burns 
 
 Sterile vaseline in tubes 
 
 Chlorazene surgical cream . . 4 ounces 
 
 Castor oil 4 ounces 
 
 Seidlitz powders 1 box of 12 
 
 Mustard, powdered .... 2 ounces 
 
 Syrup of ginger 2 ounces 
 
 Syrup of ipecac 2 ounces 
 
 Talcum powder 1 tin 
 
 Clinical thermometer ... 1 
 Red Cross first-aid packets . . 3 
 
 Uses of these remedies. Sterile gauze. This is used to 
 cover open wounds. There must be care in handling so that 
 
 FIG. 234. Various forms of handkerchief bandages: A, for the chest; 
 B, for the shoulder, hand, and arms ; C, double bandage to prevent motion 
 of the arm. 
 
 it is not contaminated. The hands should touch only a corner 
 and in no instance should they touch the part applied to 
 the wound. 
 
424 Appendix 
 
 Bandages. They are used to hold the gauze in place, 
 or give support to an injured part (Figs. 234-242). They 
 may be used for sprains and with splints for broken bones. 
 
 FIG. 235. Hand- FIG. 236. Three- FIG. 237. Four- 
 
 kerchief bandage for cornered bandage for corner bandage for 
 perineum and hip. arm. arm. 
 
 Alcohol. Used externally in sprains, strains, and bruises. 
 May be used for massage or rub. 
 
 Tincture of iodin. Used on wounds to kill the bacteria. 
 May also be used as a counter-irritant in sprains and strains. 
 Adhesive plaster. Used to give support to an injured 
 part. 
 
 Boric acid. A saturated solution is valuable for cleansing 
 and soothing the conjunctiva of the eye. Used after being 
 
 exposed to wind and dust or 
 in mild infections of the eye. 
 Aromatic spirits of ammonia. 
 
 FIG. 238. -Four-tailed bandage. ~ F r fainting, shock, Or 
 
 marked depression, it serves 
 
 as a stimulant. One teaspoonful in a half glass of water is 
 the dose. It may be repeated. 
 
 Picric acid. For burns. (See page 418.) 
 
 Sterile vaseline. Vaseline may be used in all wounds so 
 that the dressing will not adhere. It should be sterile. 
 
 Chlorazene surgical cream. Superior to vaseline because 
 of its disinfectant powers, it should be used on infected 
 wounds. It is very valuable. 
 
Appendix 
 
 425 
 
 Castor oil. This is a mild cathartic. Dose for adult, 
 1 tablespoonful ; for child 6-12 years, 1 to 2 teaspoonfuls ; 
 for infant, % to 1 teaspoonful. 
 
 Seidlitz powder. Mild purge for headache, and symptoms 
 of constipation and sluggishness of excretions. 
 
 Mustard powder. Used to 
 provoke vomiting by giving a 
 teaspoonful in a glass of luke- 
 warm water. May also be. 
 used in mixture with flour 
 (4 parts mustard and 7 parts 
 flour) for a mustard plaster 
 in bronchial and throat con- 
 ditions. 
 
 Syrup of ginger. One third teaspoonful in a glass of 
 water is used for cramps and diarrhoea. 
 
 Syrup of ipecac. One teaspoonful used with children 
 to produce vomiting. Valuable in croup because it increases 
 
 FIG. 239. Many-tailed bandage. 
 
 FIGS. 240 and 241. Four-tailed bandage 
 for the head. 
 
 FIG. 242. Four-tailed 
 bandage for the jaw. 
 
 the secretion in trachea and lessens the obstruction. 
 
 Talcum powder. Used in sunburn and for drying and 
 soothing action on skin. 
 
 Red Cross first-aid packet. This outfit contains a gauze 
 bandage, a triangular bandage, and two safety pins. The 
 gauze and triangular bandage are arranged to permit 
 
426 Appendix 
 
 application to wound without danger of contamination. 
 It is very valuable for those who are unfamiliar with the 
 handling of sterile equipment. 
 
 EQUIPMENT FOR AN EMERGENCY ROOM IN A PUBLIC 
 
 SCHOOL 
 Furniture 
 
 Two couches (rattan) 
 
 One table 
 
 Two chairs (wood) 
 Closet 
 
 Four woolen blankets 
 
 Two hot-water bags 
 
 One ice bag 
 
 Two granite basins 
 
 One dozen clean towels 
 
 Splints for broken bones 
 Medicine case 
 
 Aromatic spirits of ammonia 
 
 Toothache plasters 
 
 Bi-carbonate of soda 
 
 Picric acid (65 grains) 
 
 Alcohol (grain) 
 
 Mustard 
 
 Olive oil 
 Surgical case 
 
 Sterile absorbent cotton 
 
 Sterile gauze 
 
 Sterile bandages 
 
 Zinc oxide adhesive plaster 
 
 Sterile vaseline in tubes 
 
 Tincture of iodin 
 
 Dressing forceps 
 
 Surgical scissors 
 
 Safety pins 
 
 Book on the treatment of emergencies 
 
INDEX 
 
 Abduction, 92 
 
 Absorption from stomach, 166 
 
 Adduction, 92 
 
 Adenoids, 20, 105, 270 
 
 Adrenal, 359 
 
 Air, composition of, 268; foul and 
 fresh, 268 
 
 Albumin, 128, 
 
 Alcohol, 3, 128, 404; and the blood, 
 249; and gout, 105; and insanity, 
 411; and lead poisoning, 383; and 
 physical efficiency, 46, 408; and 
 sunstroke, 382; as a food, 405; 
 effect of, on blood vessels, 232; 
 effect of, on nervous system, 322 
 
 Alimentary canal, structure and 
 function of, 158 
 
 Amoeba, 3, 245 
 
 Animals, one-celled, 3; and primi- 
 tive society, 7 
 
 Antagonist, 125 
 
 Antiseptic, 394 
 
 Antitoxin, 375 
 
 Appendicitis, 176 
 
 Appendix, vermiform, 175 
 
 Appetite, 191, 202, 207 
 
 Artery, 212, 217; hardening of, 249 
 
 Astigmatism, 342 
 
 Athlete, 46; effect of alcohol on, 47 
 
 Athletics, 131, 138 
 
 Auricle, 218 
 
 Autonomic system, 300; function of, 
 305 
 
 Axone, 289 
 
 Bacteria, 214, 216, 371; work of, 372 
 
 Bathing, 28, 389; sea, 133 
 
 Blind spot, 341 
 
 Blood, amount of, in body, 227; 
 coagulation of, 215; carbohydrate 
 of, 216; composition of, 211, 212, 
 245; effect of alcohol on, 249; 
 effect of exercise on, 134; effect 
 of sleep on, 247; fat of, 216; gases 
 
 of, 214; germicidal power of, 214; 
 growth determiners of, 216; pro- 
 tective substances of, 216; pro- 
 teins of, 216; purification of, 250; 
 salts of, 216; table of elements in, 
 213; waste products in, 216 
 
 Blood pressure, 228; how to measure, 
 229; modification of, 230 
 
 Bone, broken, 96, 419; composition 
 of, 88; function of, 73; growth of, 
 41, 104; nourishment of, 95, 104; 
 structure of a long, 87 
 
 Boxing, 134 
 
 Brain, 292, 305; weight of, 306 
 
 Breathing, abdominal, chest, and 
 natural, 273; muscular action in, 
 271; nose, 270 
 
 Bronchus, 259 
 
 Burns, 418 
 
 Calorie, 151 
 
 Camping, 133, 139 
 
 Capillary, 217, 220, 228 
 
 Carbohydrate, 147, 151, 216, 240 
 
 Carbon dioxide, 4, 185, 211, 214, 
 220, 240, 256-281, 313 
 
 Cartilage, structure of, 40 
 
 Cells, 1, 211, 288; origin of, 4; prop- 
 erties of, 4 
 
 Cerebellum, 312; function of, 312 
 
 Cerebrum, 307; effect of removing, 
 308 
 
 Cheese, 197 
 
 Cholera, 372 
 
 Choroid, 340 
 
 Chyme, 167 
 
 Cilia, 260 
 
 Circulation, aids of, 235; action of 
 lungs on, 238; course of, 222; 
 effect of exercise on, 237, 247; 
 effect of massage on, 238; hygiene 
 of, 245; importance of good, 245; 
 lymphatic, 239; modification and 
 control of, 230, 248 ; nature of, 212 
 
 427 
 
428 
 
 Index 
 
 Circumduction, 92 
 
 Coagulation of blood, 215 
 
 Cold, taking, 246 
 
 Conductivity, 5 
 
 Constipation, 171, 177; and appen- 
 dicitis, 177 ; use of foods in, 177 
 
 Contractility, 5 
 
 Cooker, fireless, 205 
 
 Coordination of muscles, 123, 287, 
 298 
 
 Corpuscles, 212, 244; work of red, 
 213; work of white, 214 
 
 Dancing, 137 
 
 Dandruff, 24 
 
 Degeneration, 7; fatty, 128 
 
 Dendrites, 288 
 
 Development, 9, 212; of jaw, 17; 
 
 over-, 140; power of self-, 44 
 Dermis, 16-23 
 Diaphragm, 262 
 Diastole, 218 
 
 Diet, 150; of different peoples, 153 
 Dietary of Atwater, 150; of Voit, 150 
 Digestion, and environment, 191; 
 
 enzymes and, 155; of food, 158; 
 
 and health, 189 
 Diphtheria, 373 
 Disease, 3-7, 214, 374; caused by 
 
 mosquitoes, 385; table of ways of 
 
 communicating, 391, transmission 
 
 of, 393 
 
 Disinfection, 393 
 Dislocation, 96 
 Drugs, 325 
 
 Ear, care of, 349; foreign body in, 
 421; structure and function of, 347 
 
 Eating and exercise, 206; times for, 
 205 
 
 Eggs, 197, 205 
 
 Elasticity of the blood vessels, 226 
 
 Emulsion, 173, 181 
 
 Energy, effect of stimulants on, 402; 
 expenditure of, 123, 125; muscular, 
 123; origin of muscular, 42; po- 
 tential and kinetic, 43; production 
 of, 123, 400-401 
 
 Environment, 369; and digestion, 
 191 
 
 Enzyme, 155, 173 
 
 Epidermis, 24 
 
 Ergograph, 46, 142 
 
 Esophagus, 165 
 
 Eugenics, 110 
 
 Eustachian tube, 348 
 
 Evolution of the nervous system, 65 
 
 Excretion, 15 
 
 Exercise, 3, 127, 172; an aid to the 
 
 circulation, 237; corrective, 99; 
 
 effect on complexion, 29; for foot, 
 
 97; forms of, 132; and growth, 129; 
 
 and health, 131 ; the heart in, 230; 
 
 respiratory, 272 
 Expiration, 265 
 Extension, 91 
 Eye, black, 418; care of, 344; foreign 
 
 body in, 420; internal structures 
 
 of, 339 ; muscles of, 335 
 
 Fainting, 420 
 
 Fat, 147, 151, 240 
 
 Fatigue, 46, 321; meaning of, 402; 
 
 muscular activity and, 127; sub- 
 stances, 127 
 Fencing, 134 
 Fibrin, 216 
 Fibrinogen, 216 
 Flexion, 91 
 Flour, 199 
 Food, 146-157; composition of, 148; 
 
 digestion of, 158; poisons in, 378; 
 
 sources of, 193, 194; sources of 
 
 food elements, 148 
 Food values, calculation of, 151; 
 
 table of, 153 
 Foot, exercises for, 97; hygiene of, 
 
 85; proper shoe for, 87; structure 
 
 of, 85; weak, 96 
 Fruits, 196 
 Function, 6; of epithelial tissue, 13; 
 
 of skin, 24 ; of nerves, 293 
 
 Ganglion, 49, 66, 290 
 
 Germs, 214 
 
 Glands, 14; lachrymal, 337; lym- 
 phatic, 244; oil or sebaceous, 26; 
 salivary, 160; sweat, 25 
 
 Glucose, 216 
 
 Glycogen, 45, 181, 182 
 
 Grains, 198, 203 
 
 Growth, 4, 211, 216, 358; of bone, 
 41; determiners of, 216, 358; 
 effect of exercise on. 129; effect of 
 
Index 
 
 429 
 
 tobacco on, 414; and repair of 
 tissue, 52 
 
 Haemoglobin, 213, 215 
 
 Hair, 30; care of, 31; superfluous, 31 
 
 Health, 4; cleanliness and, 279; 
 digestion and, 189 ; essentials for, 
 139, 251, 280-281, 317-318, 404; 
 golden rules of, 326 ; indications 
 of, 32 ; influence of exercise on, 
 131, 140, 244; importance of cir- 
 culation for, 245 ; rules, 395 
 
 Hearing, 347 
 
 Heart, activity affecting, 230, 231 ; 
 as a pump, 217 ; rate of, 232 ; rate 
 in animals, 233 ; rate in man, 233 ; 
 tobacco, 249 ; valves of, 219 ; 
 work of, 291 
 
 Heat a form of energy, 124 
 
 Height, 129, 130 
 
 Hemorrhage, 248, 421 
 
 Heredity, 110, 129 
 
 Hockey, 136 
 
 Humidity, 269 
 
 Hunger, 353 
 
 Hyperopia, 343 
 
 Immunity, 375 
 
 Impulse, nerve, 5-8, 45, 50, 51, 232; 
 nerve, in coordination, 123 
 
 Infection, 211 
 
 Influenza, 389-390 
 
 Injury, to blood vessels, 248 ; to 
 nerves, 294 ; of body by poisons 
 in food, 378-382; of body by 
 physical agents, 382-383 ; of body 
 by chemical agents, 383-384 
 
 Insanity, 325,411 
 
 Inspiration, 264 
 
 Instincts, 132, 191, 280 
 
 Intestine, absorption from large, 176 ; 
 absorption from small, 173 ; large, 
 175 ; small, 169 ; support of, 170 
 
 Irritability, 5, 127 
 
 Joints, 89 : ligaments of, 90 ; motion 
 in movable, 90-93 
 
 Juice, digestive, 14, 156, 172; gas- 
 tric, 166; intestinal, 173; pan- 
 creatic, 172 ; salivary, 161 
 
 Larynx, 258 
 Legumes, 195 
 
 Lens, crystalline, 341 
 
 Leucocytes, 213-214 ; and bacteria, 
 392 
 
 Lever, 115 
 
 Ligament, 39, 90, 96, 98 
 
 Liver, 178; anatomy of, 178; cir- 
 culation through, 178; disturbance 
 of, 185 ; functions of, 181 ; micro- 
 scopic structure of, 179 
 
 Lung, aid to the circulation by, 238 ; 
 external appearance of, 261 ; in- 
 ternal appearance of, 260; tuber- 
 culosis of, 387 
 
 Lung capacity, 129 
 
 Lymph, 240, 241 ; cause of flow of, 
 243 
 
 Lymphatic, origin and course of, 242 
 
 Malaria, 385 
 
 Massage, 238 
 
 Meat, 196, 203 ; extracts, 197 
 
 Mechanism, neuro-muscular, 122 ; 
 table of digestive, 184 
 
 Medicine, patent, 201 
 
 Medulla oblongata, 232, 312 
 
 Membrane, mucous and serous, 14 
 
 Mesentery, 171 
 
 Metabolism, 5 
 
 Milk, 197 
 
 Molds, 370 
 
 Mosquitoes, 385 
 
 Mucus, 14 
 
 Muscle, 109-121 ; attachment of, 
 113 ; cardiac, 112 ; comparison of, 
 113 ; coordination of, 123 ; kinds 
 of, 110; names and positions of, 
 117; and nerve, 1 10 ; property of, 
 109; involuntary, 112; volun- 
 tary, 111 
 
 Muscular sense, 352 
 
 Myopia, 343 
 
 Nails, 31 ; care of, 32 
 
 Narcotic, 128 
 
 Nerve, structure of, 49-50, 289-290 
 
 Nerve center, 290 
 
 Nerves, accelerator, 232, 304 ; ac- 
 tion of, 292 ; cranial, 295 ; func- 
 tion of, 293 ; inhibitory, 232, 304 ; 
 injury to, 294 ; terminations of, 
 291 ; secretory, 15 ; of the skin, 
 25 ; spinal, 295 
 
430 
 
 Index 
 
 Nervous system, arrangement of, 
 295; effect of activity on, 317; 
 effect of alcohol on, 322 ; effect 
 of fatigue on, 321 ; effect of sleep 
 on, 318; function of, 286 
 
 Neuro-iiiuscular mechanism, 122 
 
 Nourishment, 13, 214, 239 
 
 Nucleus, 3 
 
 Nucleolus, 3 
 
 Nutrition, hobbies about, 192 
 
 Nuts, 195 
 
 Organism, 6 
 
 Organs, 6; of the circulatory system, 
 64 ; of the digestive system, 62-63 ; 
 of the excretory system, 66-67 ; of 
 the muscular system, 61; of the 
 nervous system, 64-65 ; of the 
 reproductive system, 6768 ; of 
 the respiratory system, 63, 64, 
 257; of the skeletal system, 61 
 
 Osmosis, 175 
 
 Ovum, 4 
 
 Oxidation, 42-43 
 
 Oxygen, 211, 213, 214, 220, 240, 256- 
 281 
 
 Pain, sense of, 351 
 
 Pancreas, 172, 359 
 
 Papilla, 16 
 
 Pasteurization, 379 ; value of, 381 
 
 Patent medicine, 201, 251 
 
 Periosteum, 42 
 
 Peristalsis, 165, 166 
 
 Peritoneum, 170, 171 
 
 Perspiration, 15-25 
 
 Pharynx, 163, 258 
 
 Physiology, 3, 12 
 
 Pituitary, 359 
 
 Plasma, 212 ; work of, 214 
 
 Plexus, 300 
 
 Pneumonia, 371 
 
 Poisoning, 422 
 
 Posture, 100 
 
 Pressure, of the blood, 228; sense of, 
 
 352 
 Prevention of communicable diseases, 
 
 388; of influenza, 389-390 
 Process, 4 
 
 Properties of cells, 3-5 
 Protein, 147, 151, 240; of the blood, 
 
 251 
 
 Protoplasm, 2, 213, 288 
 Psycho-motor, 122 
 Pulse, 226 
 Pylorus, 165 
 
 Reflex act, 299 
 
 Reproduction, 5 ; organs of, 67, 
 
 Respiration, 264, 282-284; artificial 
 
 416 ; hygiene of, 269 
 Retina, 340 
 Rheumatism, 162, 239 
 Rotation, 93 
 Running, 134 
 
 Saliva, 161 
 
 Secretion, 14, 168 
 
 Sensation, general, 293, 353 
 
 Senses, classification of, 232 
 
 Serum, 14 
 
 Shoe, characteristics of good, 97 
 
 Sight, 335 
 
 Skeleton, use of, 72 ; parts of, 75 
 
 Skin, dermis of, 16-23 ; hygiene of, 
 
 28; injury of, 28; organs of, 24; 
 
 protection of, 26-28 ; structure of, 22 
 Skull, 75 
 Sleep, 318 
 Smallpox, 376 
 Smell, 334 
 Spermatozoon, 4 
 
 Spinal cord, function of, 297 ; struc- 
 ture of, 296 
 Spine, curves of, 80, 81 ; function of, 
 
 79 ; deformities of, 97-100 
 Spleen, 245 
 Sprains, 96, 422 
 Stimulant, 128, 154; artificial, 402; 
 
 natural, 403 
 Stimulus, 127 
 Stomach, absorption from, 168; as 
 
 a storehouse, 168; structure and 
 
 movements of, 165, 166 
 Sugar, 147 
 Sunstroke, 382 
 Swimming, 133 
 Systole, 218 
 
 Taste sense, 333 
 
 Teeth, 16-18; hygiene of, 20; 
 
 parts of, 19 
 Temperature of the body, 212, 357; 
 
 regulation of, 357 
 
Index 
 
 431 
 
 Temperature sense, 350 
 
 Tendon, 114, 119, 126 
 
 Tennis, 133 
 
 Tetanus, 374 
 
 Theory of spontaneous generation, 
 4 
 
 Thirst, 353 
 
 Thoracic duct, 243 
 
 Thorax, 81 
 
 Thymus, 359 
 
 Thyroid, 359 
 
 Tissues, 2-5 ; building good, 52-54 ; 
 connective, 38-42; epithelial, 13; 
 kinds of, 12; muscular, 42-49; 
 nervous, 49-54 ; how the nourish- 
 ment reaches the, 239 
 
 Tobacco, 139, 413-416 ; effect of, on 
 the heart, 249 ; effect of, on the 
 respiratory organs, 279, 366 ; and 
 diseases of the throat, 163, 366 
 
 Tone, muscular, 126 
 
 Tonsils, 162 
 
 Touch sense, 350 
 
 Toxins, 374 
 
 Trachea, 163, 258 
 
 Trachoma, 338 
 
 Tuberculin, 388 
 
 Tuberculosis, 387 
 
 Typhoid, 374 
 
 Uvula, 164 
 
 Vaccination, 376-377 ; value of, 378 
 Vagus, 232 
 
 Valves, of the heart, 219; of the 
 veins, 236 
 
 Vasomotor, center, 232 ; nerves, 231 
 
 Vegetables, 200, 204 
 
 Vegetarianism, 193 
 
 Vein, 212; valves of, 236; varicos*. 
 249 
 
 Ventilation, 275-279 
 
 Ventricle, 218 
 
 Vermiform appendix, 175 
 
 Vertebra, 77 
 
 Vertebral column, 76 
 
 Vessels, effect of alcohol on blood, 
 232; function of the blood, 225- 
 228; structure of the blood, 223- 
 225 
 
 Viceroptosis, 171 
 
 Vigor, 4'; of the hair, 30 
 
 Villus, 170 
 
 Voice, care and culture, 366 ; con- 
 trol of, 360-366 ; effect of smoking 
 on, 366 
 
 Walking, 104, 131, 134 
 Waste products, 185. 216, 217 
 Water, 147, 153, 389 ; at meals, 201 ; 
 as a solvent for waste products, 214 
 Weight, 129, 130 
 Wounds, 419 
 Wrestling, 134 . 
 
 Yeast, 204, 214, 371 
 Yellow fever, 387 
 Yellow spot, 341 
 
 Printed in the United States of America. 
 
(UNIVERSITY OF CALIFORNIA LIBRARY 
 BERKELEY 
 
 Return to desk from which borrowed. 
 This book is DUE on the last date stamped below. 
 
 MAY 1 1848 
 
 
 LD 21-100m-9,'47(A5702sl6)476 
 
UNIVERSITY OF CALIFORNIA LIBRARY