How WE Live OR THE HUMAN BODY AND HOW TO TAKE CARE OF IT M^^ ^0^ *»ii^ 31 OP TH« UNIVEilSITf iim; ■m-^ t HM ^^ Q^^rtV^ Son. pCc ( '^^'h. end d./^y '^&fc/i cc '^ o HOW WE LIVE OR, THE HUMAN BODY, AND HOW TO TAKE CARE OF IT. AN ELEMENTARY COURSE IN ANATOMY, PHYSIOLOGY, AND HYGIENE. BY JAMES JOHONNOT AND EUGENE BOUTON, Ph.D. REVISED AND APPROVED BY HENRY D. DIDAMA, M.D., WIOFESSOR OF THE PRINCIPLES AND PRACTICE OF MEDICINE IN THE COLLEGE OF MEDICINE, SYRACUSE UNIVERSITY; EX-PRESIDENT OF THE MEDICAL SOCIETY OF THE STATE OF NEW YORK, AND OF THE NEW VOKK STATE MEDICAL ASSOCIATION. NEW YORK •:• CINCINNATI •:• CHICAGO AMERICAN BOOK COMPANY. FROM THE PRESS OF D, APPLETON & COMPANY. JimocAa'ioa iiBH,'' Copyright, 1884, 1885. Bv D. APPLETON AND COMPANY. WHY AND HOW. For a long time the conviction has been grow- ing that there is a radical defect in an elementary course of study which admits technical grammar, but excludes physiology, and which makes more of the classifications of expression than of the thought to be expressed. The urgent need has long been felt of giving more attention to subjects pertaining to life, those that may be a guide to thrift, health, and happiness. Legislative Action. These convictions seem to have been shared by the law-makers of New York and several other States. The recent enactments making physiology a part of the course of instruction in the public schools are evidences of this conviction ; and from every point of view the measures appear wise and beneficent. If wisely carried out, this law must be produc- tive of great good. fThe attention of pupils will be directed to the laws which govern their own being. The truths set forth will find lodgment in the brain, and in time they will find expression in daily prac- tice. As a result, we may look for improvements in food, in dress, in ventilation, in habits, in hours M750313 6 IVHV AND HOW. of work and recreation, and in everything that per- tains to living. Plan of the Book. The manifest importance of the subject is the *' why " of the book. The "■ how " remains to be considered. The book is elementary, not a scientific treatise for advanced students. Beginning with obvious relations, its method is inductive, each new topic growing out of the one that precedes it. It aims to present the laws of life in such a practical and rea- sonable way that they will become a guide to living. In the treatment of each topic, function is con- sidered before structure. The first step is to show that, for purposes of life and growth, there is a need. Then, in answer to the query as to what is done to satisfy the need, a full description is given of the organs used and the methods employed. This prop- erly subordinates structure to use, and shows the true relations of all the agencies of life. The limitations set by the term ''elementary" have forbidden minute details, abstruse discussions, and ultimate analyses. All these are left for the " High-School Physiology." Hygiejiic Lazvs. An endeavor has been made to present the rela- tions of part to function in such a way that the hygienic law applicable to the case follows as a matter of course, and scarcely needs to be stated, A law derived in this way compels assent and com- IVHV AND HOW, 7 mands obedience ; while one learned from the book is likely to remain in the mind as a mere formula. Incentives to Study. At the close of each chapter a list of questions is appended, not on the text, but rather on subjects which the text suggests. The answers to these questions wall test the pupil's powers of inference, and will incite to careful observation and study in various directions. When the questions are not matters of mere inference, one at a time should be given out at the close of each recitation, so as to allow ample time for mquiry and study. The good which will come from a judicious use of these topics may be lost by a rigid demand for a specific answer in a specified time. Alcohol and Narcotics. The provision in the new laws in regard to al- cohol and narcotics seems to be another wise and timely measure. It assumes that bad habits are largely due to ignorance. It would diminish the evils by removing the cause. It submits the solu- tion of a great social problem to science. It es- pouses no theories, but demands the exact truth. It calls upon the teacher to furnish the weapons that shall conquer prejudice, and arm the inexperi- enced against temptation. In this work, alcohol and narcotics, in their rela- tions to life, are duly treated. Wherever they are found in the body, their effects upon organ and 8 • lV//y AND HOW. function are fully described. These effects, on the whole, are seen to be so pernicious that a knowl- edge of them would seem to be an almost sufficient safeguard against evil example, which is continually inciting to evil habits. The error of over-statement has, however, been carefully avoided. Assertion without reason weak- ens a cause. The facts are sufficient. A serious mistake is made when the suspicion is aroused that an effort is made to establish a case, rather than to ascertain and state the truth. Practical Application. This and all kindred works will be of little use if thought stops with the text. What is said is valua- ble only as it "■ wakes up mind," and leads to further study, and to the observance of hygienic laws in daily practices. The teacher who allows his pupils to sit in draughts, and pays no heed to ventilation and the arrangement of light, and who is careless in regard to his own diet, dress, and hours, of sleep, will teach physiology to little purpose. The pupils should be made to see, to study, and to experiment. The word should lead to work. Prin- ciples should direct practices. The understanding of conditions must precede conscious obedience to law, but obedience is the desired end. Full mental conception of the subject in its relations will, in time, yield fruit in the direction of more healthful bodies, more vigorous minds, and lives made richer by the accomplishment of good deeds. WHAT AND WHERE. CHAPTER J. PAGE The Body and its Parts 13 Why we should Study our Bodies : Some Things easily seen — Others require Study — Natural to avoid injur- ing Outward Parts of the Body — Study needed to know how to take care of Organs within the Body — Why we should look well and keep healthy. About Parts of the Body : The Arms — The Legs — The LimBs and Joints — Parts of the Body in Pairs — The Bodies of other Animals — Uses of the Parts of the Body. Something to Find Out. CHAPTER n. Eating, and what Comes of It 21 Why we Eat : The Body always wearing out — We eat that we may live. What we Eat : Kinds of Food — ^Value of Different Kinds — Special Foods — Mixed Foods. How we Eat : Mastication— The Teeth— Care of the Teeth— How to keep the Teeth clean. How we Swallow : How Saliva flows — Amount of Saliva — How Saliva is wasted — Tobacco — The Esophagus. Hygiene of Mastication. Some- thing to Find Out. CHAPTER HI. How Digestion Goes On 35 The Stomach : Structure — Muscular Action — Gastric Juice — Changes in the Stomach — Chyme — The Absorbents — 10 WHAT AND WHERE. PACK Drink — Alcohol in the Stomach — Absorbing Power — The Alcohol Habit. The Intestines : Structure — Intestinal Juices — The Duodenum — The Pancreas — Office of the Pan- creatic Juice — The Liver — Bile — Office of the Bile — Chyle — Alcohol in the Liver — Absorption — The Portal System — The Lacteals — The Thoracic Duct — Summary of Changes. Hy- giene OF Digestion. Something to Find Out. CHAPTER IV. How THE Blood gets Purified 46 The Heart: Its Position— The Plan of the Heart- Auricles and Ventricles — Pulmonary Action. The Lungs : Structure of the Lungs — Bronchial Tubes — The Trachea — The Larynx — The Pleura — How the Chest varies — Forces in Breathing — Inspiration — Expiration — Action in the Lungs — Results of Breathing — Return of the Blood — Alcohol in the Lungs — An Unnecessary Burden — Tobacco in the Lungs — Produces Stupor — The Need of Pure Air. Hygiene of Respiration. Something to Find Out. CHAPTER V. How the Blood Nurtures the Body .. . . .58 Waste and Repair — The Arteries — The Capillaries — The Veins — Action in the Heart — Action in the Arteries — Action in the Capillaries— Action in the Veins — Alcohol in the Blood — Does not become a Part of the Blood — Hinders the Effect of Oxygen — Injures the Walls of the Heart — Enlarges Mi- nute Divisions of the Arteries. Hygiene of Circulation. Something to Find Out. CHAPTER VI. How the Body is Able to Move 66 Motion necessary to Life. The Muscles : General Structure— Connective Tissue — Parts of Muscles — Tendons — Hollow Muscles — How the Muscles act — Voluntary and In- voluntary Muscles — Flexors and Extensors — How the Muscles WHAT AND WHERE. \i PAGE gain Strength — The Muscles need Rest — Exercise for Health, not for Strength. Hygiene of the Muscles. Something TO Find Out. CHAPTER VH. How THE Body is Able to Stand . . . , yy The Need of a Bodily Frame. The Bones : Uses of the Bones — Forms of Bones — Structure of the Bones — Materials of which the Bones are made — Growth and Repair of the Bones — Bones of the Head — Sutures of the Skull — Bones of the Trunk — Bones of the Arms — Bones of the Legs — Bony Cavities of the Body. Bodily Movements : How the Mus- cles move the Bones — How Shocks are distributed. Hygi- ene OF the Bones. Something to Find Out. CHAPTER VIII. How the Body is Covered . . . . . .91 The Usefulness of the Bodily Covering. The Skin : General Structure of the Skin — Layers of the Skin — How the Skin is kept soft — How the Skin casts out Waste Matter — How the Skin regulates Heat — How the Skin absorbs — Why the Skin should be kept clean — How to keep the Skin clean. The Hair: What it is — How to keep the Hair healthy — Thinning and Grayness of the Hair. Clothing; Why the Body should be clothed — How the Body should be clothed. Hygiene of the Skin. Something to Find Out. CHAPTER IX. How Bodily Motion is Directed 107 Bodily Organs must act in Harmony. The Nervous System ; How the Nerves are distributed — Nerve-Matter — The Brain — The Spinal Cord — The Ganglions — Sympathetic System — Use of the Nerves — Direct Nerve-Action — Reflex Action — Sympathetic Action — Habit and Training — Exercise of the Nerves — Rest of the Nerves — How Alcohol affects the Nerves — Staggering — Effect on the Mind — The Lower Na- 12 WHAT AND WHERE. PAGB tiire in Control — How Tobacco affect^ the Nerves — Inherit- ance. Hygiene of the Nerves. Something to Find Out. CHAPTER X. How THE Mind gets Ideas and Expresses Them . 122 Sensations — The Need of Special Senses. The Sense of Taste : The Taste as a Sentinel — Flavors — Taste not a Per- fect Guide in the Choice of Foods. The Sense of Smell : Odors. The Sense of Hearing: Sound — Its Production — The Ear — Care of the Ear. The Sense of Seeing: Light — Need of Light — The Eye — Its Structure— Muscles of the Eye — Action of Light — Care of the Eye. The Organs OF Speech : The Need of Expression— The Voice — Speech — Care of the Voice. Hygiene of the Organs of Special Sense. Something to Find Out. CHAPTER XI. Stimulants and Narcotics 137 I. Stimulants : Unnecessary — Injurious. 2. Narcotics. What the Words Mean 141 Topical Analysis 156 Bones of the Body 166 Where to Find Things 169 HOW WE LIVE. CHAPTER I. THE BODY AND ITS PARTS. IV/iy we should Study our Bodies. When we look at our bodies, we see that they are made up of parts. Each of these parts has a name and one or more uses. We know the most common of these names and uses ; but, unless we have studied them with care, there are many im- portant and interesting things about them that we do not know. If any one should ask us the name of the highest part of the body when standing erect, we would answer that it is the head. We could also tell the names and the uses of the outer parts of the head. Perhaps we could make pictures of them. We would, likewise, be able to tell that the part of the body next below the head is the neck ; that the largest part of the body is the trunk ; that the parts attached to the upper portion of the trunk are the arms ; and that those attached to the lower portion of it are the legs. But, if some one should ask us about what is inside of the head, neck, or trunk, we would be un- 14 HOW WE LIVE. able to answer from observation, and we could not tell either the names or the uses of the parts. Yet each of these inside organs has a work to do in the support of life ; and the peculiar work which each does and its curious way of doing it are matters of great interest. When a bee stings us, or we burn our fingers, we can tell the cause of the pain ; and we shall be careful to avoid it in the future. But when we have earache or headache, we can not always tell the cause. By the study of those parts of the body which we can not see, we may so change our course of conduct as to avoid many aches and diseases. If we see a person's tooth broken off, or his eye bhnded by some accident, we shall never know- ingly expose ourselves to the same danger ; yet, by want of knowledge, we may neglect or abuse our teeth or e3^es in such a way that they will be as surely destroyed as by a visible accident. Most of the internal organs are soft and deli- cate ; and when once injured they are afterward, in many cases, weak and nearly useless. By knowing what care they need, we may avoid injuring them, and so escape pain and disease. It is necessary, therefore, that we should know a great deal about the parts of the body. We should know not only their names and uses, but also what will make them stronger or weaker. Then we shall know how to preserve our health, and thus be able to keep ourselves in the best con- dition to do our work in the world. Looks are important. We like to see good- THE BODY AND ITS PARTS. 15 looking people. We should desire to look well, so that our appearance will please others. One of the most important elements of good looks is health. A sickly person loses that clearness of complexion, that sparkle of the eye, and that elasticity of step and vigor of motion which we all admire. By keeping in health we also enjoy life much better. We suffer less from bodily pain ; we see things more clearly, and succeed better in what we undertake ; we can take care of ourselves, and thus avoid becoming a burden to our friends; and we are more ready to perform any duty that may pre- sent itself. Besides, we are more cheerful. We do not take gloomy views of life, and make ourselves generally disagreeable ; and, while we are happier ourselves, we make others happier also. About Parts of the Body, The Arms. — We see that the arms form a pair, and are fastened sidewise to the trunk just below the neck. They extend in opposite directions, and end in hands, which continue in the same direction as the arms. The hands terminate in fingers, and the ends of the fingers are protected by nails. The Legs. — The legs are joined to the lower part of the trunk and extend downward, ending in feet, which are at right angles to the legs. At one extremity the foot has a heel, and at the other it terminates in toes, which, like the fingers, are pro- tected by nails. The Limbs and Joints. — The arms and legs when taken together are called limbs. All the i6 HO IV WE LIVE. limbs are attached to the body in such a way that they can move in every direction. The point of at- tachment is called a joint. If we examine a leg of mutton, or the leg of a chicken, which we may have on the table at dinner, we find in each a bone with a round head fitting into another bone having a cup-like cavity. These bones form what is called the ball-and-socket joint. Such a joint we have at the shoulders and the hips, where the arms and the legs are attached to the body. The sockets at the shoulders are not so deep as those at the hips, and this arrange- ment allows the arms much greater freedom of movement. We see that a door is attached to the jamb in such a way that it can swing in only two direc- tions, backward and forward. This kind of attach- ment is called a hinge. The arms at the elbows, and the legs at the knees, have only a forward and backward movement, and hence these joints are called hinge-joints. The double or compound joints at the wrists and the ankles admit of a great variety of move- ments, and are made up of several small, rounded bones which move about each other. The knuckles Fig -Ball-and-socket joint of the hip. THE BODY AND ITS PARTS. 17 2. — Hinge -joint of the elbow. and the toe-joints, like those of the elbows and the knees, are hinge-joints. The lower parts of the arms and legs have also a turning or twisting motion, so that we can turn our hands completely over and our feet in and out. This motion is brought about in the arm by an arrangement of two bones which extend through the lower part of the limb, and which turn about one another. Parts of the Body in Pairs. — Besides the pairs of arms and yig. of legs, we have two ears, two eyes, and twp cheeks. If we examine closely, we shall see that the nose has two nostrils, and that the two sides of the mouth are ahke in structure. This arrangement of the exter- nal parts of the body in pairs makes it double ; so that, if it were divided by a line running down from the middle of the forehead, it would be in halves, each with the same parts turned in opposite directions. The Bodies of other Animals. — If we examine other animals, we shall see the same general plan of structure — parts in pairs, and opposite sides alike. The parts of other animals correspond to parts of our own bodies in many respects, agreeing in num- ber, position, and general use, but differing some- what in form. Thus the cat and the dog have four limbs each : but their arms are fore-legs ; their hands, paws ; and their nails, claws; l8 HOW WE LIVE. The horse and the cow also have four limbs each ; but, in the place of toes, the horse has a sin- gle hoof, and the cow a double one. The chicken's arms are wings ; the bat's four limbs are connected by a thin, delicate skin, forming wings with which it can fly ; the four limbs terminate in feet, two of them webbed for swimming ; the fish's four limbs are fins ; and nearly all the vertebrates are provided with the same number of limbs, showing a general plan in creation, or, as Agassiz expresses it, "a thought of God." Uses of the Parts of the Body. — In each one of us the part that thinks, or the mind, is the most im- portant. The mind in thinking makes direct use of the brain. The brain is in the head, and is pro- tected by the skull. Every time the mind thinks, a tiny part of the brain wears out and must be repaired. The ma- terials for the repair come from the blood. Hence we must have a way of making blood. For this pur- pose we have a trunk ; and this is large, so that it may contain everything necessary for the process. To make blood, we must have food ; and to get food, we have arms to reach out and take it, and legs to go in search of it. We thus see that all the parts are made expressly for the service of the mind ; and that by their proper action alone can the mind be kept in good condition. One would think, then, that the mind, if it is sensible, would take good care of the body. THE BODY AND ITS PARTS. 19 Something to Fifid Out, . 1. Why should we try to look as well as we can ? 2. What are some of the things necessary to good looks that we all can attend to ? 3. Which of the ball-and-socket joints are most easily put out of joint ? Why ? 4. What kind of joint unites the thumb to the hand? 5. How many joints have the fingers ? the toes? 6. How does the great-toe differ from the thumb? 7. How does the ankle differ from the wrist? 8. How do the cat's toes correspond in number to our fingers and toes ? 9. How do the cat's fore-paws differ from our hands ? 10. What joint in the dog's hind -legs corre- sponds to our hips ? knees ? ankles ? 11. What bone in the cat's leg represents our heel? 12. On what part of the foot do we tread? On what part does the dog tread ? 13. Explain what is meant by the term digiti- grade — plantigrade. 14. Give two examples of digitigrade animals — of plantigrades. 15. To which of these classes does the horse belong? the cow? the sheep? the bear? the ele- phant ? 16. Why are the bones of the skull made very strong ? 20 ^OW WE LIVE. 17. What animals use their fore-paws to hold their food while eating ? 18. How does the duck's foot differ from that of a chicken ? 19. What do birds have in the place of mouth and nose ? 20. In what way can we best avoid mistakes in taking care of the body ? Note. — At the latter end of the book, commencing on page 156, will be found a topical analysis for each general subject treated in the several chapters. These outline statements may be made of great value to teacher and pupil, as showing the relations of the topics and sub-topics to each other, and as affording a scientific basis for exami- nations and reviews. CHAPTER II. EATING, AND WHAT COMES OF IT. W/ij^ we Eat, Every motion that we make, and every thought that we think, destroys some of the minute cells of which the various parts of the body are composed. If this waste goes on without repair, the parts soon wear out, and the body dies. The process of re- pair is called nurture, and the elements of nurture are found in food. Before the food can nurture the body, it must undergo many changes. It must be broken up ; parts of it must be dissolved ; different parts must be mixed with each other; and the useful parts must be separated from those which are worthless. The first step in this process is eating. We eat, then, that we may live. We eat, that every part of our bodies may be strengthened, and that we may be able to do our daily work. What we Eat. Upon our tables, for breakfast or dinner, we have meat, bread, potatoes, fish, fruit, and many other articles of food to eat ; and water, milk^ and 22 HOW WE LIVE. other liquids to drink.* We must take this food and drink at regular times, to satisfy the demands of appetite and the needs of the system. As the body is composed of many different ele- ments, the food and drink which we take must con- tain these elements. If we take no food, we starve ; if we take food that lacks some needed element, after a time we starve just as certainly. More of the elements which the body needs are found in some articles of food than in others. But, as no one food contains all kinds and sufficient quantities of needed elements, we are obliged to take a variety of foods — one kind furnishing the elements which the others lack. Kinds of Food. — One of the most valuable of all the foods is the gluten, or sticky part, of flour. It contains all the elements which the body needs, but not all of them in sufficient quantity.f Nearly the same elements are found in the albumen, or white, * The pupil should here enumerate the different kinds of food in common use, and find out all he can about each. For example : bread is made of wheat ; the wheat grows in our fields ; the grain is taken to the mill and ground ; and the meal or flour is made into bread. This treatment of the subject serves to introduce both farming and manu- facturing operations, and to show their relation to our needs. Again, take rice, another common article of food. This grain does not grow in our fields, but is the product of a warm, lowland region. The description of its place and manner of growth serves to show the relations of food to geography, and to give a new and vital interest to that branch of study. In like manner, tea, coffee, sugar, salt, and many othei articles may be made to serve a similar purpose f Wheat, the most valuable of our grains, contains a large amount of gluten. Fine white flour contains little gluten, and, when we make bread of it, we lose the best part of the grain. The " new-process " flour retains the gluten, and makes excellent bread. EATING, AND WHAT COMES OF IT 23 of ^gz^\ in the myosin, which is the principal part of lean meat; in the caseine, or curds, of which cheese is made ; and in the fibrine which constitutes the clot of the blood. These foods are known as proteids, or albuminoids. Another substance of great value as food is the starch that forms a large part of the grains and other vegetable products. Starch does not, how- ever, contain so many of the needed elements as gluten, and is therefore less valuable as food. The same elements in differing proportions are found in sugar and in the vegetable gums. These foods are known as amyloids y' The third class of foods includes all oily sub- stances, both animal and vegetable, and are known as fats. They are composed of the same elements as starch and sugar, but they so differ in form that they need a different treatment before they can nourish the body.f Minerals form the fourth class of substances that may be ranked as foods. They include lime, soda, potash, iron, salt, and water. These are all found * Starch forms a large part of all the grains. Potatoes contain but little besides starch and water. Peas and beans are more than half starch. Tapioca, sago, arrowroot, and rice are nearly all starch. Beets, turnips, and other garden vegetables are principally made up of starch, sugar, and water. f All the kinds of food given above not only furnish the elements of nurture, but each helps to furnish the heat necessary for the well- being of the body. But, while the proteids are best for nurture, the sugars and the starches are also needed. The amyloids have great power of producing heat, but the fats have still greater. In the frozen regions of the extreme north, oil is one of the most necessary articles of diet. 24 ffOlV WE LIVE. in the body, and must be contained in the different articles of food. These substances, with the excep- tion of salt, are found in sufficient quantities in meat, in fruit, and in vegetables. Special Foods. — Of the vegetable foods, Avheat- flour and oatmeal contain the greatest number of needed elements, and come the nearest to perfect foods. Corn-meal is rich in starch and fats, but has little gluten. Peas and beans have a large portion of vegetable caseine, a substance that resembles glu- ten, and they are ranked very high as foods. As they are not easily digested, however, they should be taken only in small quantities by those who have weak stomachs.* Beef is the best of all the kinds of meat. Next to this comes mutton. Chicken and turkey have nearly the same elements, with the exception of the fats. Veal, lamb, and pork have less of the elements which the body needs, and are harder to digest. Eggs and milk are nearly perfect foods. Fish and oysters are among the best of foods. Clams, crabs, and lobsters are less easily digested. f * Graham-flour, containing the whole of the wheat-grain, makes sweet and wholesome bread. Rolls made of this flour, by simply mix- ing the flour with water or milk, and then pouring the thin batter into a hot roll-pan, and baking in a hot oven, are among the best forms of bread that can be made. The garden vegetables generally are made up of starch and sugar and a large amount of water. f Meats are best when broiled or roasted. They should be exposed to a hot fire at first, so that a crust may be formed on the outside to preserve the inside juices. In making soups, the meat should be put in cold water, and brought very slowly to the boiling-point, so as to extract the juices. EATING, AND WHAT COMES OF IT. 25* Fruits are mostly made up of starch and sugar, but they also contain more of the mineral matter needed by the system than is found in most other foods. The acid of fruits is also an aid to diges- tion. Fruits are chiefly valued, however, for their agreeable flavors, which gently excite the digestive organs ; and when taken in moderate quantities they are very wholesome.^ Mixed Foods. — Our study so far has shown us that no one substance is a perfect food, and there- fore that a mixture of foods is necessary to secure all the needed elements. Experience has taught us the same lesson, and the custom is general of mix- ing foods in such a way that one will supply the needed elements which the others lack. Thus bread, rich in gluten, lacks starch or fat, and butter is added ; potatoes, mostly starch, are eaten with meat, gravy, or butter. How we Eat. Mastication.— The first step toward reducing food to a condition in which it can nourish the When milk produces an unpleasant effect upon the stomach, it should be mixed with a little lime-water. Fish and oysters should not be eaten unless perfectly fresh. * Strawberries, raspberries, blackberries, currants, cherries, peaches, apples, melons, and oranges are all excellent, and their moderate use, each in its season, will, many times, make the doctor's visit unneces- sary, and save us from a course of medicine. The puipy substance of unripe fruits is often hard and tough, and the juice strong and sour. When fruits, in this condition, are eaten, they can not be digested, and both pulp and juice cause irritation and often inflammation of the digestive organs. Fruits are made whole- some by ripening and by cooking. 26 HOPV WE LIVE. body is chewing, or mastication. The organs di- rectly used in chewing are the teeth, the tongue, and the cheeks. The teeth grind the food. The tongue and the cheeks keep the food between the teeth so that it may be ground. The Teeth. — If we examine the mouth of a cat or a dog, we discover four prominent teeth that are long and pointed. The other teeth, both front and back, are shorter and smaller. These sharp teeth can easily pierce soft substances, and seem to be of just the right shape for tearing flesh. In the mouth of a squirrel or rabbit we find the prominent teeth, four in number, directly in front. These teeth are long ; but, instead of being pointed, they have a sharp edge like a chisel, which fits them for cutting hard substances or gnawing. If we look into the mouth of a horse, we find the prominent teeth broad and flat, the exact shape for grinding grain, or for breaking in pieces the soft stalks of plants. In our own mouths we find teeth like those of the dog, the rabbit, and the horse ; but they are all nearly alike in size. The four cutting teeth on each jaw in front are called incisors ; the four pointed teeth, one on each side of each jaw, next back of the incisors, are called ca?iine teeth, or cuspids ; the eight teeth next to the cuspids are the bicuspids ; and the twelve back teeth, six on each jaw, are molars. The parts of the teeth that lie inside the bones of the jaw are the roots, and the part of each tooth that appears outside the gums is the crown. Usu- EATING, AND WHAT COMES OF IT. 27 ally, the molars of the upper jaw have three roots each, and those of the lower jaw have two. The cuspids and incisors have only one root each. - — b d Fig. 3. — The jaws and the teeth : i, 2, incisors ; 3, canines ; 4, 5, bicus- pids ; 6, 7, 8, molars ; a, vein ; ^, artery ; c^ nerve ; d^ vein, artery, and nerve. If we carefully examine a tooth, we find that the crown has a hard, smooth outside. This is called the enamel. Under the enamel is a softer kind of bone called dentine. In the middle of the tooth, and extending to the end of each root, is a cavity in the bone, through which extend a nerve and a net-work of blood-vessels. 28 I/O IV WE LIVE. Fig. 4. — Section of a tooth Ay enamel ; B, nerve cav- ity ; C, C, roots. Care of the Teeth. — When the enamel is broken the tooth decays, causing severe pain and an un- pleasant breath. To prevent these troubles, the teeth should receive special and constant care. Some boys try to crack hard nuts with their teeth, but crack the enamel instead, and so spoil their teeth. Biting hard substances of any kind has the same effect. A pitcher when cold may be easily cracked by pouring into it a stream of hot water. The sudden and irregular change of temperature causes the break. In like manner the enamel of the teeth may be cracked by abruptly changing from cold to hot foods, as from ice-cream to hot tea. When food gets lodged between the teeth and is permitted to remain there, a kind of gas is formed which destroys the enamel and causes the whole tooth to decay. How to keep the Teeth Clean. — After each meal, the food lodged between the teeth should be carefully removed by a tooth-pick of wood or quill. The use of a pin or a penknife is apt to injure the teeth or the gums. On rising in the morning, after each meal, and before going to bed at night, the teeth should be cleaned with water and a tooth-brush.* * The tooth-brush should be stiff enough to remove all food from the teeth, but not so stiff as to injure the gums. EATING, AND WHAT COMES OF IT. 29 A little fine salt may sometimes be used with profit. Powdered orris-root, used sparingly, will help to keep the breath sweet. A hard substance, known as tartar, sometimes collects on the inside of the teeth, next the gums, and, if permitted to remain, will destroy both teeth and gums. When it begins to collect, this tartar may be readily removed by scraping the teeth with the broad end of a quill tooth-pick. How we Swallow. After the food has been chewed enough, it is to be swallowed. Before swallowing, saliva is mixed with it, moistening it, and making it slippery, so that it will go down easily. The saliva is furnished by the salivary glands of the mouth, and is obtained from the blood. How Saliva Flows. — The salivary glands do not pour out saliva all the time, but are excited to ac- tion in various ways. The movement of the jaws will produce a flow of saliva. In chewing, this flow is enough to moist- en the food, and in talking it is usually suflicient to keep the mouth moist. Touching any part of the mouth, or the presence of anything in it, will cause the saliva to flow, as every one knows who has been under the hands of the dentist. The sight, smell, or taste of food when we are hungry will also *' make the mouth water." This may be seen by watching a cow when she is look- ing on while her supper of turnips is in course of 30 HOW WE LIVE. preparation. The saliva is produced in such quan- tities as to flow out of the corners of her mouth. Articles of a pungent taste, like mustard, pep- per, horse-radish, and tobacco, make the mouth hot, causing a free flow of saliva. Amount of Saliva. — We need just enough saliva to moisten our food. When we do not get enough, we find it difficult to swallow, and then there is trouble in the stomach. To get this amount takes time. Those who eat hastily, and bolt their food without chewing, may look forward to a time when they can not eat with any comfort, and when they will have no strength for work, or play, or enjoy- ment of any kind. We need to eat slowly and chew our food very fine, so that the movement of the jaws will cause enough saliva to pour out. Bread and vegetable foods need more chewing than meats. All flow of saliva in excess of the amount needed for the moistening of the food and the mouth is waste. The blood from which it comes is made thinner and poorer, and has less of the materials necessary for the repairs of the body. How Saliva is Wasted. — If we keep our jaws in motion when we are not eating, a useless flow of saliva is produced, which is waste of material and weakening to the body. Chewing gum and all like habits are therefore hurtful. Tobacco. — The most fruitful cause of waste in saliva, however, is the use of tobacco. The pun- gent qualities of this narcotic produce an excessive flow, and, when the exciting cause is constantly kept EATING, AND WHAT COMES OF IT. 31 Up, the amount wasted often becomes serious and exhaustive. Again, by this waste the materials of the blood by which saliva is furnished gradually diminish. The saliva itself becomes weak, inactive, and unable to perform its special work in the stomach ; and, besides, other materials needed elsewhere are con- tinually drained off. , One other effect of the use of tobacco needs to be mentioned here. It gives an unpleasant odor to the breath, and often causes a disagreeable habit of spitting ; so that clean, sensitive, and refined persons do not like to have those who use tobacco come near them. The Esophagus. — The esophagus is the tube through which the food passes from the mouth to the stomach. When the food is sufficiently chewed and moistened, it is pressed backward by the tongue, and falls into the pharynx^ a portion of the throat which lies immediately above the esoph- agus. On its way to the pharynx it passes over the en- trance of the windpipe, but is kept from falling into it by the epiglottis, a valve which shuts down when the food comes along. Sometimes the epiglottis does not close quickly enough, and a particle of food, getting into the windpipe, chokes us, and causes us to cough until it is thrown out. By eat- ing slowly we avoid this danger. Muscles extend around the esophagus, and when the food enters from the pharynx they contract, the upper one first, and then the next in order, thus 32 ^OIV WE LIVE, gradually forcing the food into the stomach. The process of eating is now done, and that of digestion is ready to proceed. Hygiene of Mastication. From the foregoing study of the subject we de- rive the following laws in regard to mastication : I. Take food that will best nourish the body. II. Eat slowly, to give the time necessary for the proper action of all the organs of mastication. III. Chew food until enough saliva is obtained to moisten it. IV. Do not injure the teeth by biting hard sub- stances. V. Avoid exposing the teeth to sudden changes of temperature. VI. Keep the teeth clean. VII. Swallow slowly, so as to give the epiglottis time to act, and thus avoid choking. VIII. Be sparing in the use of highly seasoned foods that induce too great a flow of saliva. IX. Do not keep the jaws in motion by chewing gum and other substances not needed as food. X. Avoid the use of tobacco, as it wastes saliva, weakens the body, and makes the person using it disagreeable. Something to Find Out. 1. What other grains besides wheat are raised on our farms ? 2. What garden vegetables do we raise to eat ? 3. What part of the corn-plant do we eat ? of the EATING, AND WHAT COMES OF IT. 33 potato-plant ? of the beet ? of the onion ? of aspara- gus ? of cabbage ? 4. What substance in dough makes it stick to- gether ? 5. How is wheat-bread made Hght? 6. Why is it more difficult to make corn-bread light? In making corn-bread, what is the effect of mixing the white of eggs with the corn-meal ? 7. Why is fat meat more eaten in winter than in summer? 8. How is the oil necessary for food obtained in the frozen regions ? 9. Why is more wholesome food made from Graham-flour than from fine white flour ? 10. Why is beef as a food better than pork? 11. Why are oysters better than clams? 12. Why is it better to roast beef than to boil it? 13. In boiHng meats, should they be put into cold or hot water at first ? 14. In what condition should oysters and fish be when used for food ? 15. Of what benefit is the acid of fruits? 16. Why are green fruits unwholesome? 17. How may green fruits be made wholesome? 18. What kind of food should be mixed with the proteids ? What with the amyloids ? 19. In cooking, what is usually mixed with maca- roni ? Why ? 20. Mention other foods that are usually eaten together. 2 1 . What are milk-teeth, and what care do they need ? 34 HOW WE LIVE. 22. When the permanent teeth show signs of decay, what should we do ? 23. Why should we be sparing in the use of mustard and horse-radish ? 24. When people know that the use of tobacco is hurtful, why do they not leave it off? 25. What is the best way to avoid the trouble of leaving off the use of tobacco ? 26. What evils follow from eating too rapidly ? CHAPTER III. HOW DIGESTION GOES ON. To nourish the body, food taken into the stom- ach must be converted into blood. The process of preparing food to enter the blood, called digestion, takes place chiefly in the stomach and intestines. Stomach Digestion. Structure. — The stomach is a sack or bag in the lower cavity of the body, and holds from one to two quarts.^ It has two openings. Through the up- FiG. 5. — The stomach. * The trunk has two cavities, the chest and the abdomen. These cavities are separated by a thick, muscular membrane, called the dia- 3 36 HOW WE LIVE. per opening, or cardiac the food comes in Irom the esophagus ; and through the lower opening, or pylorus, the food, when in a proper condition, passes out into the intestines. The stomach is made up of three coats. The outer, or serous, coat is strong and smooth. Its glossy surface is moistened by the serum from the blood, so that, when it rubs against the walls of the trunk, or against any of the other organs, there is no friction. The middle coat is made up of muscles, which extend around the stomach in both the longest and shortest ways. These muscles contract and ex- pand, giving motion to the stomach, and churning its contents. The inner, or mucous, coat is soft, and lies in little ridges or folds, giving a great amount of sur- face. This coat secretes from the blood a fluid, known as the gastric juice, which flows in large quantities when the stomach is full. The churning process brings the gastric juice into contact with the food, and thoroughly mixes the contents of the stomach. Food Changes. — The saliva, mixed with the food, is one of the agencies for changing the amy- loids into grape-sugar — a process necessary to fit these substances to enter the blood. The gastric juice dissolves the proteids, such as the albumen of eggs, the gluten of grain, and the fibrine of meat, and makes them fit to enter the blood. phragm. This membrane is attached to the walls of the trunk, and forms the floor of the chest and the roof of the abdomeri. HOW DIGESTION GOES ON. 11 A small portion of the food is taken up from the stomach by capillaries, called absorbents, and carried at once to the portal vein. But by far the greater part is converted into a slimy, fluid mass, called chyme, and passes through the pylorus into the in- testines. Drink. — At each meal enough drink should be taken with the solid food to moisten the mass in the stomach. If too much is taken, the gastric juice is so diluted and weakened that it can not properly perform its work. For the action of the mucous and muscular coats of the stomach, and of the absorbents, the animal heat must be kept up. By drinking ice-water, or any very cold drinks, with our meals, the heat is diminished, and the work of digestion goes on slowly, or not at all, until the heat is restored. Alcohol in the Stomach. — When stimulants con- taining alcohol are taken into the stomach, the first effect is to excite the mucous coat, and increase the flow of the gastric juice. If the drink is con- tinued from day to day, the gastric flow increases, and is excessive. In consequence, it becomes thin and weak, and is unable to perform its proper work of digestion. But alcohol has a great power of absorbing water. It takes moisture out of the mucous coat of the stomach. By continually drinking it, the stomach becomes hardened, and is unable to supply gastric juice enough for digestion. If the drinking is then kept up, more or less active inflammation always sets in, often causing long illness, or death. 38 1^0 IV WE LIVE. Alcohol has another peculiar effect. Its action on the stomach often leaves a sickly, sinking sensation, which can be relieved only by alcohol ; and so drink induces drink, until the habit is formed from which no one can escape without great suffering. While the alcohol is busy with its work in the stomach, the absorbents are trying to get rid of it. They take it up unchanged, and pass it on into the blood-vessels, ready to repeat elsewhere the mis- chief it has begun in the stomach. Intestinal Digestion. Structure. — The intestines are tubes lying in a coil, through which the food passes after leaving the stomach. The small intestine is about one inch in diameter and twenty feet long. The large intes- tine is twice as large, and five feet in length. This gives to the whole canal below the stomach a length of about twenty-five feet. Like the stomach, the intestines have three coats, serous, muscular, and mucous. The mucous coat secretes from the blood and pours out in small quantities the intestinal juices. These mix with the chyme coming from the stomach, and convert into sugar a portion of the starch which has before es- caped digestion. The muscular coat of the intestines consists mostly of rings, and these, beginning with the one nearest the stomach, contract, one after the other, like those of the oesophagus. This action forces the contents downward, and finally expels the waste portion from the body. HOW DIGESTION GOES ON. 39 / k j Fig. 6. — The organs of digestion : a, duodenum, leading out of the pylorus; ^, liver ; r, esophagus ; d, pancreas ; e^ stomach ; /, spleen ; g^ t\ j\ k, w, «, parts of large intestine ; //, /, small intestine. The Duodenum. — The upper part of the small intestine, about twelve finger-breadths in length, is called the duodenum. The chyme enters this canal from the stomach, and on its passage receives two fluids known as pancreatic juice and bile^ and these still further prepare the food for the nurture of the body. The Pancreas. — The pancreas is an organ lying back of the stomach, irregular in shape and about 40 HOW WE LIVE. six inches long."^ It secretes pancreatic juice from the blood, and pours it out into the duodenum to mix with the chyme. The pancreatic juice is al- kaline, and neutralizes acids. It also acts upon un- digested amyloids, proteids, and fats. When the chyme enters the duodenum, the oily portion lies on the surface. The pancreatic juice unites with it and divides it into minute particles and mixes it through the whole mass of chyme, as the oily particles of cream are divided and mixed in milk. A part of the oil is converted into a sub- stance resembling soap. The Liver. — The liver is a large organ lying on the right side under the lower ribs. It secretes bile from the blood and pours it out into the duo- denum. The portion of the food taken up by the absorbents and carried to the veins passes through the liver. In the liver-cells a sugary substance called glycogen is secreted, and conveyed by the hepatic veins into the general circulation. The office that bile has to perform is not fully understood. That it is waste matter which the blood must get rid of, is shown by the fact that, when resorption of the bile takes place, the body becomes yellow with jaundice. It is pretty well un- derstood that the bile assists the pancreatic juice in reducing fats ; that it supplies alkali to neutralize the acid of the chyme ; and that it stimulates in the intestines a mucous secretion which lubricates them and renders the passage of waste matter easy. * In animals whose flesh we eat, the pancreas is called sweet-bread, and is considered a great delicacy for the table. HOW DIGESTION GOES ON, 41 Alcohol in the Liver. — The alcohol expelled from the stomach makes its next appearance in the liver, whither it is carried through the portal vein. Here, if continued from day to day, it also changes the tissue, so that the work of the liver is imper- fectly done or suspended altogether. If the drink is then kept up, inflammation often sets in, causing much suffering and frequently ending in death. From the liver the alcohol passes unchanged into the veins. Absorption. — By the action of the pancreatic juice, and the bile in the duodenum, the chyme is converted into a milky substance called chyle, and continues its way through the intestines. In its passage, the portions fit to make blood are taken up by the absorbents and lacteals and are carried to the veins. The mucous coat of the stomach and the intes- tines is covered with a net-work of minute veins, and into these a portion of the food is carried directly. These veins all empty into the portal vein, which terminates in the liver. After a change effected by the liver, through the hepatic veins, this material is poured into the large vein ascending from the lower extremities. The Lacteals. — All along the intestines are little absorbent tubes known as lacteals.'^ These unite in little groups and form larger tubes. These at last all terminate in a single tube, about the size * It is estimated that these lacteals number about seven thousand in each square inch of surface, and that in the entire length of the intestines they number from three to five millions. 42 HOW WE LIVE. of a goose-quill, which lies in front of the spinal column, and is known as the thoracic duct. i- f Fig. 7, — The lacteals and their connections : a, portal vein ; 3, g, thoracic duct ; c, groups of lacteals ; d^ e^ intestine ; /", lacteals. The greater part of the chyle is absorbed by the lacteals. It is carried to the thoracic duct. Ascending through that tube, it is poured into a vein which lies under the left collar-bone, or clavi- cle, and is known as the subclavian vein. It now finds its way to the heart through the currents from the upper extremities. Summary of Changes. — Food is masticated in the mouth by the teeth, and is mixed with saliva. The aiHyiei^s are digested by the action of the saliva, the pancreatic juice, and the intestinal juices, and by a change effected in the liver. HOW DIGESTION GOES ON, 43 The proteids are reduced, or dissolved, in the stomach by the gastric juice. Acids are neutralized by the alkali of the bile. Oily substances are reduced in the intestines by the action of the bile and the pancreatic juice. These several changes complete digestion, and change food so that it readily enters the blood. Hygiene of Digestion. Like other parts of the body, the digestive or- gans need rest. If kept constantly in action, they become weary and unable to perform their proper work. From this fact, and from the lessons which have gone before, we derive the following hygienic laws : I. Take food that can be digested. II. The food should be so prepared as to digest most easily. III. Enough food should be taken to nourish the body, and no more."^ IV. Food should be taken at regular times, with intervals between sufficient to give the digestive organs a chance to rest.f * The best guide to the proper kind and amount of food is a health- ful appetite. As there is a pleasure in eating, however, there is danger of eating too much, especially if the food is taken rapidly. The appe- tite, too, may be spoiled by various indulgences, and then it ceases to be a guide. In such cases the only way we can determine what is best for us is by the study of the nature of foods, and by experience as to what seems to suit our own conditions best. f If children must eat candy and sweetmeats, the best time for them is directly after a meal, as the habit of eating between meals is very injurious. After a long process of digestion, the tiny digestive organs become tired, and it is wrong to overtax them. We ourselven 44 HOW WE LIVE. V. At meal-times, and until digestion in the stomach is nearly finished, water and other liquids should be taken sparingly. VI. Avoid the use of tobacco, as it prevents the changes which should be made by the saliva. VII. Avoid the use of alcoholic drink, because it prevents the changes which should be made by the gastric juice and by the liver. VIII. Avoid all substances, like unripe fruits, that have a tendency to create disturbances in the intestines. Something to Find Out. 1. What would be the effect if the serous coat of the stomach should become rough ? 2. What would be the effect if the muscular coat should cease to act ? 3. What effect has the gastric juice upon starch? 4. When the mouth is full of food, should we take drink to '' wash it down " ? 5. Why is it better to take drink toward the end of a meal than at the beginning? 6. What is the effect of taking ice-cream after a meal? 7. How do vinegar and sour fruit sometimes improve digestion ? 8. Why are biscuits containing a large quantity of soda hurtful ? 9. Under what circumstances may it be proper to take a little soda into the stomach ? need a rest after a hard task, and are discouraged, if, when our work seems to be done, more is given us to do. So it is with the little lacteals and absorbents. It is not fair to keep them constantly at work. HOW DIGESTION GOES ON, 45 10. Should we take food ''between meals"? Why? 11. Should we eat just before going to bed? Why? 12. What is the harm of eating when we are tired ? 13. Should we engage in violent exercise just after a meal ? 14. What is the best condition to be in for the half-hour before and after meals ? 15. What are the best foods for invalids and per- sons with weak stomachs ? 16. What is the general difference between a proper summer and winter diet ? 17. How can we avoid the evil effects which tobacco causes in the stomach ? 18. In what way is the habit of taking alcohoUc drinks formed ? 19. How can we avoid the suffering caused by breaking off such a habit ? 20. Why do people begin the use of strong drink ? 21. What is the effect of eating so much at a meal as to overload the stomach ? 22. Mention some remedy for the evil of over- eating. 23. What is better than medicine to preserve a healthy digestion ? CHAPTER IV. HOW THE BLOOD GETS PURIFIED The newly made blood brought by the lacteals and absorbents is poured into veins, where it min- gles with the currents returning to the heart. This blood is laden with materials which the body no longer needs, and before it can nurture the body it must be purified. For this purpose, it must come in contact with air, to which it may give off the waste matter it contains, and from which it may receive oxygen. The Heart. On its way to the air, the venous blood first en- ters the heart. This organ is placed in the chest between and partly behind the two lungs, and slightly on the left side. It is about as large as the fist, and is shaped somewhat like a pear. It points downward toward the front. It is made up entirely of strong muscular fiber, so that it can con- tract with very great force.* It is surrounded by. * It has been found that, during twenty -four hours, the average healthy human heart does an amount of work equivalent to raising 92.425 tons one foot high, or of raising one ton over 92 feet high. A HOW THE BLOOD GETS PURIFIED, 47 a smooth, satin-like membrane, called the pericar- dium. Fig. 8.— The heart and large blood-vessels : A, right ventricle ; B, left ven- tricle ; C, right auricle ; Z>, left auricle ; E, aorta ; F, pulmonary artery. The Plan of the Heart. — The heart, like many other parts of the body, has a double structure. good climber can only raise his own weight 9,000 feet in nine hours, or 1,000 feet an hour ; while the work done by the heart is equivalent to raising its own weight (ten ounces) 13,860 feet an hour. The most powerful engine ever made by man, the *' Bavaria" locomotive of the Vienna and Trieste Railway, can only raise itself through 2,700 feet in an hour ; that is, its energy is less than one fifth of that of the human heart. — (" The Heart and its Function.") 48 ^OIV WE LIVE. Its right and left sides are entirely separated b}? an unbroken wall of muscle. In structure, the two sides are nearly alike, but each side has its own separate work to do. The right side, which re- ceives the blood from the veins and sends it to the lungs to be purified, is soitietimes called the pulmo- nary heart ; and the left side, which receives the blood from the lungs and sends it out to nurture the system, is called the systemic heart. Each side of the heart has two cavities, the smaller one being above, and the larger below. The upper cavities are called auricles, and the lower ones ventricles. As the blood flows from the veins into the auricles gently, the walls of the upper part of the heart are not so thick and strong as if they were intended to sustain a heavy strain. From the ventricles the blood must be forced or driven, through the blood-vessels, and, in conse- quence, the muscular walls of the ventricles are thick and strong. Between the auricles and ventricles are valves opening downward, which admit blood freely from above, but which close and prevent its return. The blood-vessel leading from the right ventricle to the lungs is called \\yq pulmonary artery. Pulmonary Action. — The currents from the veins, one from the upper extremities and one from the lower,* unite and empty into the right auricle of the heart. The walls of the auricle contract, and force the blood through the valve into the right * The large vein from above is called the superior vena cava ; and that from below, the inferior vena ca-va. HOW THE BLOOD GETS PURIFIED. 49 ventricle. The powerful muscular walls of the ven- tricle then contract, the valve shuts, and the blood is driven through the pulmonary artery to the lungs, where it comes in contact with the air. The Lungs. The lujigs are in two divisions, occupying the right and left sides of the upper part of the chest. Fig. 9. —The cavity of the chest, showing the positions of the heart and the lun^ : Ay left lung ; B, heart ; Z>, pulmonary artery ; E^ trachea, or windpipe. The right side has three distinct parts called lobes^ the left has two. Structure of the Lungs. — The lungs are made so HOW WE LIVE, up of soft, elastic tissue arranged in the form of minute cells. These cells are connected with small Fig. io, — Air-passages in the human lungs : ^, larynx ; *, trachea ; c, d^ bronchi ; pend our breath for a brief time, but soon the motion of breathing will be resumed in spite of the will. A case is on record of a man who could by an effort of his will control the beating of the heart. He tried the experiment of stopping his heart " once too often," and it never began again. The care of the body during sleep is shown when the hand brushes away a fly that lights on the nose, but does not waken the mind. Coughing is caused by spasms of reflex action operating upon the muscles in the lungs. When a bit of food gets into the trachea, the cough-spasm throws it out. Diseases of the lungs produce the same feelings as the presence of foreign substances, and hence lung-diseases are accompanied by coughing. Sneezing is a similar spasm produced by foreign substances or disease in the nose. The hiccough is a nervous spasm of the diaphragm, caused by exhaustion, as from excessive laijgh' \ex. or from the effect of alcohoL 114 i/0^ WE LIVE. to all the vital organs, and these organs are thus placed in direct communication and sympathy with one another. This nervous connection is called the sympathetic system. When the stomach is out of order, the sympathetic nerve gives notice, and the heart and lungs sympathize and become deranged in action. Disturbance in one organ is felt in all the others.* Habit and Training. — In every action which comes from thought, the mind, through the brain, directs the first steps. When the actions are re- peated a sufficient number of times, the muscles be- come accustomed to the movement, and the act is performed with ease. When this is the case, the direction of such acts is given over to the lower nervous centers, and the actions are performed with little or no consciousness. The name given to this unconscious repetition of an action is habit.\ The precision and rapidity * This sympathy gives rise to many needless fears. A person eats too much, and the stomach labors hard to get rid of the oppressive load. In sympathy with this effort, the beat of the heart becomes feeble and irregular. Then the terrible fear comes that the heart is diseased, and that death is near. The doctor comes, laughs at the fears, gives a little mustard, and the patient is well the next day. The use of tobacco produces " heart-burn," a trouble of the stomach, and this in turn, through sympathetic action, causes palpitation of the heart. f Habits once formed are difficult to overcome. Habits formed in youth are the most lasting. The old man is slovenly because as a boy he was untidy. The fine scholar can not in his oration entirely get rid of the inelegant expressions of his childhood. The cruel boy becomes the brutal man. Good habits are equally durable. The kindly acts of the boy or the girl ripen into kindness in the man or the woman. When effort to do things well becomes a fixed habit, it makes life rich in well-doing. HOW BODILY MOTION IS DIRECTED. 115 of action which come from habit constitute skill ; and the method by which skill is obtained is train- ing/^ The training which converts acts into habits relieves the mind and the brain, and leaves them free to study new things and to perform new acts. Exercise of the Nerves. — Like the other parts of the body, the nerves require exercise. The food furnishes the elements of nerve-growth, but exer- cise is necessary to make their growth vigorous and to secure strength. When the mind is engaged in observing objects, finding out their qualities, and comparing them with other objects, it is giving direct exercise to the sensory nerves. When the hands are doing something under the direction of the mind, the motor nerves are brought into exer- cise. In both these cases, and in all thinking, the brain is exercised. If nerve-exercise is omitted, the whole body suf- fers, the vital organs are feeble in their action, the blood moves slowly in the veins and the arteries, waste is imperfectly made up, the muscles become flabby and weak, and the brain is so little nourished that at last it becomes incapable of vigorous action. The starved mind, working through the starved brain, gradually loses the vitality it had at first, until it becomes little better than idiotic. To prevent this * A young lady beginning to play the piano is obliged to fix her whole attention upon the position of her hands and upon the keys she is to strike. When training has given her skill, she strikes the keys cor- rectly without thinking, and she is able to give her whole attention to the music. In like manner, skill enables the workman to do his best work with the least conscious attention. 8 Il6 HOW WE LIVE. result, the mind requires daily activity in careful study, or in directing some useful work.* Rest of the Nerves. — The nerves also need rest. Like the muscles, they become tired with exercise. Nightly sleep furnishes the necessary rest for proper daily exercise. If, during the day, the nerves are unduly exercised or strained, they become weary, and sleep does not restore their vigor. If the strain is continued, sleep is broken, the weariness in- creases, and the nervous system breaks down, leav- ing the person a helpless burden to others. Ex-. cessive study, or excessive work of any kind, which requires brain-labor, often results in congestion or softening of the brain, or in paralysis. How Alcohol affects the Nerves. — Alcohol and other narcotics have a tendency to paralyze the nerves, and so diminish their power to act. This effect first shows itself in the nerves which con- trol the passage of the blood through the small arteries. The half-torpid nerves can not sufficiently control the rush of the blood, and the minute ves- sels are gorged. This gives to the skin a peculiar redness, which is very observable in the dehcate skin of the face. The brain is affected in a similar manner, and is gorged with blood, causing great * The nerves are greatly affected by emotion. By a joyous and happy mood nervous action is increased, the vital organs are stimulated to do their v\^ork well, and a glow of health pervades the whole body. Grief diminishes nervous action. Sudden bad news sometimes so para- lyzes the nerves that the heart ceases for a time to beat, and faintness, or even death, is the result. Ill temper, envy, sulkiness, and all kinds of selfishness and meanness, diminish nerve-force, and tend to derange the action of the vital organs. 'how bodily motion is directed. 117 activity and tumult, but not the orderly action which produces good thinking and leads to useful doing. If the alcohol is continued until the habit of drinking is formed, the derangement of the nerves becomes more marked. The heart is weakened and grows feeble in its action ; the nerves lose con- trol of the muscles and the limbs stagger ; and there is a general derangement of all the organs, because the nerves Avhich ought to produce harmony of action are paralyzed. Effect on the Mind. — The cerebrum is the seat of intelligence and of the moral nature. Through the cerebrum the mind directs and controls bodily action. The cerebellum is the seat of the nervous influence that more immediately affects the body, and it controls the regular order of unconscious action, like walking. Alcohol much more quickly paralyzes the cerebrum than the cerebellum. In consequence, when drink has been taken in excess- ive quantities, both the intelligence and the moral nature are dead for a time, and the appetites and passions have full sway. In this way a man is often converted into a brute, dangerous to his family, to his neighbors, and to himself. Continued drunken- ness often ends in delirium and death. How Tobacco affects the Nerves. — The general use of tobacco diminishes nervous action. Its ha- bitual use is not so destructive as that of alcohol, but still it is a substance which enters into the sys- tem without furnishing any needed element. It is in the body, but not of it. When used to excess, it Il8 HOW WE LIVE. has a particularly paralyzing effect upon the nerves which control the muscles of the heart, weakening its action to such a degree as often to cause spasms and insensibility. Inheritance. — Children inherit from their par- ents nerves weakened by the use of alcohol and to- bacco, and the lives of thousands of innocent per- sons are thus made miserable. Usually the first drink and the first smoke are found to be very dis- agreeable, but quite often an inherited appetite shows itself, and the sweet breath of the child be- comes foul with the whisky and tobacco which can not be kept out of his way. Beginning with this unnatural appetite, habits are speedily formed which make his life a burden to himself and to others. Hygiene of the Nerves. As the nerves control all the movements of the body, both conscious and unconscious, and thus affect its nourishment, we need to take the greatest care to keep them healthy, and especially to avoid all courses likely to injure them. I. We must observe all the laws of digestion, so that the brain and the nerves may be supplied with pure blood. II. We must avoid breathing foul air, or the nerves will be paralyzed by the impurities of the blood. III. To keep it in health, the brain should every day be brought into vigorous action by some form of study or thinking. IV. Active daily exercise, by either work or HO IV BODILY MOTION IS DIRECTED. 119 play, is necessary to secure the healthful action of the nerves distributed through the body. V. We need a great variety of objects to ob- serve, to handle, and to study, in order that the sensory nerves may receive sufficient exercise. VI. We need a great variety of work, having the stimulus of a useful purpose, that the motor nerves and the brain may be excited to healthful action. VII. When we are tired we need rest, because as much nervous force as we can spare has been used up. Sleep, the natural rest from daily toil, should be regular, and should continue until the vigor of the nerves is restored. VIII. The hardest study and the closest think, ing should be done when the nerves are most vig- orous, and that is usually during the first half of the day. IX. We should never try to think or study when we are sleepy. In the first place, we then need sleep more than knowledge ; and, in the sec- ond place, we gain very little knowledge when the mind is weary. X. We should avoid continued and excessive mental work, because it may become so exhausting as to break down the whole nervous system. XI. When the nerves have become so exhausted that we can not sleep, we must give up all labor and thinking until the nerves have recovered their lost strength. XII. Cramming for an examination is much more exhausting than a much longer period of regular study, and should be avoided. I20 I/O IV IVE LIVE. XIII. We should try to do those things which will form good habits, so that we may easily and certainly perform good deeds throughout life. XIV. We should take special pains to avoid doing anything which tends to form bad habits, because it will be always difficult, and sometimes impossible, to correct such habits when they have once been formed. Something to Find Out. 1. In study, what should always be our object? 2. In the study of science, what evils come from trying to learn the exact words of a text-book ? 3. What is the effect ol adding careful experi- ment to the study of a subject ? 4. In case we do not understand a subject that we have studied, what is to be done ? 5. Why is it injurious to attempt to hold the breath for any considerable time ? 6. When we have eaten too much, what symp- toms, besides sickness at the stomach, may we ex- pect? 7. After we have learned to walk, what nervous action controls walking ? 8. What trouble would come if the cerebrum were obliged to control walking? 9. Why is it easier to perform an act the second time than at first ? 10. What is the result of doing one act re- peatedly ? 11. When we perform acts without much think- ing, what have we acquired ? HOl^l^ BODILY MOTION IS DIRECTED. 121 12. What kinds of acts lead to the formation of good habits ? of evil habits ? 13. What does a person need in order to be- come a good base-ball player ? 14. What term is applied to persons who do not like to exercise either body or mind ? 15. What good do we get from play that we do not get from work ? 16. What good results from work that does not come from play ? 17. Why is night the best time for sleep? 18. What good comes from having sleep at regu- lar hours ? 19. Why should w^e give up study when we are sleepy ? 20. What kind of games are beneficial to stu- dents while attending school ? 21. What kind of games would rather injure than benefit them? 22. Explam how a game may be beneficial to a farmer when it would injure a student. 23. What class of people is most benefited by a week's fishing in summer? 24. What good comes from the use of alcohol when we are in health? From the use of tobacco? 25. How does alcohol affect speech? 26. Why may a drunken man be considered in- sane? 27. In what way can we best avoid the dangers and miseries which come from drunkenness ? 28. How may we escape from the danger of heart-trouble caused by tobacco? CHAPTER X. HOW THE MIND GETS IDEAS AND EXPRESSES THEM. Sensations. — The sensory nerves receive im- pressions from objects and carry them to the brain. These impressions are called sensations. When the sensation is fully known to the mind, it is called an idea. Since the skin most directly comes in con- tact with objects, it has the greatest supply of sen- sory nerves. From nerves in the muscles we get ideas of pressure and weight. Through the nerves of touch in the skin we get from the surface of ob- jects the ideas which are expressed by the terms hard and soft, rough and smooth, hot and cold. But these ideas are not enough. The mind needs to know about flavors and odors ; it rnust get from sound its meaning and its music ; and from light it must learn the beauty of form and color. For these purposes some of the sensory nerves take the form of special nerves of sense, as those of taste, smell, hearing, and sight. The Sense of Taste. The Taste as a Sentinel. — Special care must be taken that improper food be not admitted into the HOW THE MIND GETS IDEAS. 123 stomach. The mind must keep close watch over all things eaten, and must reject such as will be likely to injure any part of the body. One of the agents which the mind uses to determine whether food is wholesome or unwholesome is the sense of taste. Flavors. — When food is taken into the mouth, it gives an impression which we call flavor."^ The nerves upon which flavors make an impression give us the sense of taste, and are called gustatory nerves. They are distributed over the tongue and the back part of the mouth. Many substances taken in the mouth may be felt but not tasted. Touch takes notice of certain quaUties of all substances; but taste notices flavors only, and is not aroused to activity until the surface of the substance yielding the flavor is dissolved by saliva. We can get no idea of flavor except through the gustatory nerves. Before flavors can be perceived, the substance must come in direct contact with the nerve. When a strong flavor has been tasted, the impression will remain for some time, and will prevent other flavors from making their proper impression. Except in disease, the flavor of most wholesome foods is pleas- * The primary and strongest flavors are sweetness, sourness, saltness, and bitterness. Besides these, there are the flavors peculiar to difter- ent fruits, such as peaches, grapes, etc., and the flavors peculiar to the different varieties of the same fruit, as that of Catawba and of Dela- ware grapes. It is thought by some that all possible flavors are made up of different combinations of the four primary ones ; but this point is not settled. 124 ^^^ ^^ LIVE, ant, and the necessary act of daily eating is thus ren- dered agreeable.* The Sense of Smell. Odors. — Another of the agents employed to test foods is the sense of smell. When certain sub- stances are brought near the nose, they make an impression which is called odor. The nerves upon which odors make an impression give us the sense of smell, and are called olfactory nerves.f These nerves are distributed through the cavities of the nostrils. Substances smelled do not come in con- tact with the olfactory nerve. Such substances give off something that we call aroma, or odor. In no way can we measure or weigh odor. It is only known through the sense of smell. Agreeable odors give us a sense of pleasure, and also stimulate the whole nervous system. * The sense of taste is not a perfect guide in the choice of foods. One of the conditions of good digestion is that food shall be palatable. But palatable food is not always wholesome, and the mind must have other means of deciding what shall be eaten. The act of eating is agreeable ; but, if we give ourselves up to the pleasures of the appetite, swine have an advantage over us, as they ap- pear to enjoy eating even better than we do. f The olfactory nerve notices nothing but odors. Unpleasant odors denote the presence of something hurtful. Food that is tainted, or that gives off an unpleasant odor, is unfit for the human stomach. Air that smells vile is unfit to breathe. A keen sense of smell is very desirable, and it will be well to always " follow the nose " when it leads away from bad odors. -ikae HO IV THE MIND GETS IDEAS, 125 The Sense of Hearing. Sound. — Whenever an object of any kind moves, a portion of the air is disturbed and set in motion. Whenever an object has a continued motion to and fro, a similar wave-hke motion, or vibration, is set up in the air. These vibrations strike upon the ear, and produce an impression which is called sound!^ The nerves that receive impressions of sound are the auditory nerves, and the sense that has sound for its object is the sense of hearing. It is necessary that the mind should know what movements are going on around it, so that it may avoid danger, and take advantage of circumstances to carry out its purposes. It should be able to dis- tinguish different sounds for the pleasure that music affords. The mind must also be able to distinguish and produce the sounds used in articulate speech for the purpose of understanding and of expressing thought. These ends it accomplishes by means of the ear. The Ear. — The ear, which is the organ of hear- ing, has three parts : the outside or external ear, * The least number of vibrations that produce a sound which the ear can perceive is sixteen per second. As the vibrations increase in rapidity, the sound becomes higher in pitch. The highest sound that the ear perceives is made by about thirty-two thousand vibrations per second. Vibrations below sixteen and above thirty-two thousand per second are silent to the human ear. The sense of hearing may be cultivated so that the ear will detect sounds which are not audible to other ears, and will observe differences which were before unnoticed. This cultivation makes life richer by the new enjoyments which it affords. 126 HOW WE LIVE. which we see ; the middle ear, or tympanum, which is a small passage through the bones ; and the in- Fig. 30. — The parts of the ear: a, external ear; 5, passage; c, membrane cf the tympanum ; d — m^ bones and their connections ; n — r, interior canals and openings ; i, 2, 3, small bones of the ear, highly magnified. ternal ear, which consists of several winding pas- sages in the bony structure of the skull. The three parts of the ear are separated by thin membranes which stretch across each end of the tympanum like the head of a drum. A passage, called the Eustachian tube, opens from the tympanum into the throat.* The vibrations of the air striking the outer mem- * Through the Eustachian tube, air is admitted to the inside of the tympanum, so that the pressure upon both sides of the ** ear-drum " is equal. When we have a cold and the throat is swollen, the mouth of this tube is closed, and we become quite deaf for a time. The remedy is, not to doctor the ears, but to cure the throat. I/OJV THE MIND GETS IDEAS. 127 brane of the tympanum cause it to vibrate, and the motion is conveyed to the auditory nerve, which is spread over the passages of the internal ear. This gives the impression of sound. The quahty and in- tensity of the vibrations are in some measure regu- lated by a chain of minute bones within the tym- panum, and by the hmpid fluid which fills all the passages of the internal ear. The auditory nerve notices nothing but sound. Care of the Ear. — The ear needs little care ex- cept to be kept clean ; otherwise it should be let alone. The wax which lines the inner passage is bitter, and prevents insects from crawling in.* It should not be removed. In summer, boys, while in swimming, often get water into their ears. It fre- quently remains for a considerable time, and is very disagreeable. This difficulty may be prevented by stuffing a little cotton into the ears before going into the water. The Sense of Seeing. Light. — It is now generally believed that light, as well as sound, is produced by vibrations. But while sound comes from vibrations of the air, light is the result of vibrations of a fluid much thinner than air, and which fills all the space between the earth, the sun, and the stars. These vibrations make no impression upon any of the nerves of the * In spite of all care, an insect sometimes gets into the ear, where its movements sound exceedingly loud. When this happens, oil may be used to destroy the life of the intruder, and then the ear may be cleansed by means of a soft cloth. 128 HOW WE LIVE, body except the optic nerve of the eye, and here it gives the impression which is called light.* Need of Light. — The mind needs to know the forms and positions of objects. The body, in travel- ing in search of food, must avoid the abrupt preci- pice, the dangerous pit, the deep water. It must have some sure guide to the things necessary to its existence. The mind must be able to judge of dis- tance for purposes of use and protection. It also has higher needs. For its own growth and happi- ness it must be able to see the beauty which color unfolds, and which is found in the shifting scenes of mountain and sea, and in the varying forms of ani- mal and vegetable life. All these come to the mind by means of light and through the eye. The Eye. — The eyes are spherical bodies about one inch in diameter, and are placed in bony sockets in the front part of the skull. On all sides, except the front, they are protected by strong bones and cushions of soft tissue. The eyelids, with rows of eyelashes along their edges, can close over the front of the eyes, so as to protect them from dust and in- sects. The eyebrows turn the sweat on the fore- head away from the eyes. Tears keep the eyes moist, and winking spreads the tears over their surface.f * By means of a prism it is sliovn that light is composed of many colors. Differences in color are supposed to come from difference in the rapidity of the vibrations which produce light. •)• A tube connects the tear-gland with the nose, so that extra tears usually flow through it. In case of great grief, or anger, the tears overflow, and this excess of tears is called weeping. Sometimes the tube leading to the nose gets obstructed, producing what is termed a " weeping eye." NOW THE MIND GETS IDEAS. 129 Structure. — The eye has three coats. The scle- rotic coat, on the outside, is strong and tough. It serves to keep the eye in shape, and also as a place Ofi.\ Fig. 31. — Horizontal section of the eyeball: Scl, sclerotic coat ; Cn, cornea; Ch, choroid ; /r, iris ; Aq^ aqueous humor ; Cry, crystalline lens ; Vt, vitreous humor ; Rt^ retina ; Op, optic nerve. of attachment for muscles. This coat has an open- ing in front, in which a convex transparent mem- brane called the cornea is placed, very much as a crystal is inserted in a watch. Next, inside, is the choroid coat, made of softer tissue, and containing the blood-vessels that supply the eye. The interior part of this coat is black or very dark-colored.* The retina, or inside coat, is formed by the spread- * The dark interior surface of the choroid coat absorbs the light ■which is not needed for clearness of seeing. When this black coloring- matter is wanting, as in the case of albinos, vision is defective. I30 HOW WE LIVE. ing out of the optic nerve over the back part of the eye. The crystalline lens is a transparent body, shaped like a convex eye-glass, only much thicker in the middle. It lies near the front of the eye, encircled by the sclerotic coat. The space back of the crys- talline lens is filled with a transparent, jelly-like substance called the vitreous humor ; and the space between the crystalline lens and the cornea is filled with a watery fluid called the aqueous humor. In front of the crystalline lens is a colored curtain called the iris. Through the iris is an opening called the pupil, through which light is admitted. The muscles of the iris are so constructed that in a dim hght they enlarge the pupil so as to admit more light, and in strong light they diminish the pupil so that some of the light is shut out.* Muscles of the Eye. — Muscles in the interior of the eye change the form and position of the crys- talline lens, and enlarge and diminish the iris for the purpose of adjusting the light. The motion of the whole eye is controlled by four straight mus- cles which move it up and down, and from right to left. Besides these, one muscle goes through a pulley, and rolls the eye around in its socket.f * The effect of light upon the iris may be seen by observing the eyes of a cat. In a strong light the pupil closes so nearly that it ap- pears only as a faint line. In a dim light the pupil enlarges so much that the iris neai'ly disappears. f When the interior muscles are too strong, the eyes are turned toward the nose, producing internal strabismus, or " cross-eyes." "When the exterior muscles are too strong, exterior strabismus results. These difficulties can be easily remedied by a skillful surgeon. HOW THE MIND GETS IDEAS, 131 Action of Light. — The light enters the eye through the cornea, and passes through the aque- ous humor. The iris here steps in and shuts off all light not needed. The crystalline lens next receives the light that the iris permits to pass, and so adjusts itself that the light falls upon the retina in just the way to make the right impression of form. When vision is perfect, an exact image of the object seen is made upon the retina.* Care of the Eye. — The crystalline lens is some- times too convex, producing short-sightedness. This trouble calls for the use of concave glasses. As old age comes on, the crystalline lens becomes flattened, and convex glasses are needed. When we read or study, the Hght should be thrown upon the book or object, and not into the eyes. A glare of hght in the eyes makes objects appear dim. On the other hand, we should avoid trying to read or see small objects in a dim light. If the strain which such a practice occasions is continued, it is liable to weaken the eyes and produce temporary or per- manent blindness. Cross-Hghts, or lights coming into a room at different angles, are hurtful to the eye. As these lights are of different intensity, the muscles of the iris become weary of trying prop- erly to adjust the ever-changing light. * Get from the butcher the eye of an ox ; carefully cut away the sclerotic coat on the back side ; then darken a room, except one ray of light. In this opening place the eye, as though looking out. On the retina can then be seen a distinct image of objects outside, but they appear upside down. From the same eye may be obtained an idea of the brilliancy and transparency of the vitreous humor. 9 132 HOW WE LIVE. The Organs of Speech. The mind has need to express thought as well as to receive it. It needs not only to learn from the experience of others, but also to give to others the result of its own experience. The most effect- ive means by which this interchange of ideas is brought about is the voice as heard in speech. Cer- tain combinations of sounds are called words, and words express ideas. The Voice. — The larynx is the prominence which lies immediately above the trachea. The triangular opening from the mouth into the larynx is called the glottis. Along each side of the glottis are thin membranes called vocal cords. These mem- branes usually hang loose, but they can be stretched and made to vibrate. They then produce sound in much the same way as it is produced by the vibrat- ing strings of a musical instrument. This sound is the voice. Speech. — The sounds of the voice will be higher or lower as the vocal cords are more or less tight- ened, and so vibrate faster or slower. By slight changes in the opening of the glottis the sound can also be made to vary in quality and quantity. The voice, coming out through the mouth, is shaped into articulate speech by the teeth, tongue, palate, roof of mouth, and lips, under the direction of the mind.* * Speech is chiefly a matter of imitation. Children who are accus- tomed to hear correct speech will usually speak correctly. During the first three or four years of school-life, distinctness of speech may be pro- moted by giving raiher more than the usual prominence to the syllables HO IV THE MIND EXPRESSES IDEAS. 133 Care of the Voice. — Scarcely anything is more to be desired than a pleasant voice. The possessor of such a voice is sure to be heard when no heed is given to others, and his presence gives pleasure where that ot others would give pain. To secure the possession of these pleasant tones, care must be taken not to put too great a strain upon the vocal cords in youth. Screaming, loud wrangling, bois- terous singing, and hallooing, all have a tendency to break or harden the vocal cords, so that afterward they can make none but coarse and harsh tones. Care must also be taken not to use the vocal cords much when the throat is sore from any cause. Hygiene of the Organs of Special Sense. I. When things taste bad, we should examine them with great care, and know that they are not harmful before we eat them. II. We should be careful not to injure the sense of taste by the use of tobacco and other pungent substances. III. Things that smell bad should be avoided. IV. It is well to refresh ourselves and to stimu- late our nerves by a very moderate use of perfumery. V. Keep all hard instruments out of the ear-pas- sages. VI. Do not sit facing the light. VII. Do not use the eyes much in a dim light. VIII. Do not try to study or look closely with cross-lights or other uncertain and varying lights. of words. Later the same object may be gained by short daily drills upon the vocal elements of the language. 134 ^OlV WE LIVE. IX. Do not attempt to see much when the eyes give notice of exhaustion by sleepiness or pain. X. Do not strain the vocal cords by continued loud and high tones in singing or in speech. XL Use the voice gently at the period when it is " changing," and always when there is any in- flammation of the throat Something to Find Out. 1. What part of the skin is best supphed with sensory nerves, and is therefore the most sensitive ? 2. What can we find out by the sense of touch ? 3. Why does a piece of marble feel cooler than a piece of fur that lies by its side ? 4. Does it ever happen that the marble feels warmer than the fur under the same conditions ? 5.. Why can we not taste a piece of marble ? 6. How can we tell the flavor of a fruit that we have heard described but have never seen? 7. What old fable shows the folly of deciding upon the flavor of grapes that grow out of reach? 8. Why can we not relish the flavor of a peach just after taking quinine ? 9. What difference does the gustatory nerve per- ceive between the surface of a piece of iron and that of a piece of soft, cotton cloth ? 10. Why should we take considerable time for each of our meals ? 11. Why should we not usually spend several hours at a meal ? 12. Why are roses and lilacs so frequently plant- ed about houses ? HOW THE MIND GETS IDEAS. 135 13. What would be the effect, if fragrant flowers could be planted around all homes ? 14. Why should we object to having a tannery or a slaughter-house put up near our dwelling ? 15. In what way can we turn to profitable ac« count the decaying vegetable and animal substances which give off bad odors ? 16. Why should we cultivate a liking for pleas- ant odors, and learn to discriminate between them? 1 7. What animals are noted for keenness of scent ? Of what use is this sense to them ? 18. What are some of the disadvantages of being deaf? 19. What pleasures of a high character do we get through the ear ? 20. What special charms has an early morning walk in the country in summer ? 21. When near by, why is the shrill whistle of a locomotive or the clang of a gong disagreeable ? 22. Read from Goldsmith's " Deserted Village " the description of summer evening sounds. What sounds are described, and why do they all make so pleasant an impression ? 23. What advantage has the cultivated musician over one who has no taste for music ? 24. What difference in shape do you notice be- tween the pupil of a cat's eye and that of your own? 25. What differences do you notice in the iris of the eyes of different persons ? 26. What in other parts of the body corresponds 136 //OIV WE LIVE. to the coloring of the iris, and the black coloring- matter of the interior of the eye ? 27. What is the color of the eyes of an albino, and why is his sight defective ? 28. What are some of the useful ideas which we get through the eye ? 1 29. What pleasurable emotions come from trav- eling among the mountains ? 30. What from observing the sea ? What from a walk in the garden ? 31. How does voice differ from speech ? 32. What are some of the disadvantages of a harsh voice ? 33. What does a pleasant voice indicate ? 34. Why should not httle children be permitted to sing " at the top of their voices " ? 35. What advantage comes from always hearing clear and pleasant tones in speech ? CHAPTER XI. STIMULANTS AND NARCOTICS. /. Stimulants. Unnecessary.-^Continuous exercise without in- termission is impossible. Even the heart, which seems always busy, rests more than it works. It re- poses and feeds between its beats. Its resting spells are short, but they come often. They occupy three fifths of the time, so that in twenty-five hours the heart works but ten and reposes fifteen. When muscular or mental exercise is too violent or prolonged, fatigue is felt. The waste of muscu- lar or brain substance is greater than the repair. Food and rest relieve the fatigue. The repairing materials are supplied by the food ; they are used during rest. The food should be sufficient but not excessive in quantity ; nutritious, easily digestible, and varied in quality. The time devoted to eating and repose should be ample. It should not be stinted nor be- grudged as if it were misspent. When the various parts of the body are in a healthy condition, only food and rest are required to enable them to exercise their functions to the best advantage. 138 HOW WE LIVE. In disease there may be emergencies when stimu- lants are useful and necessary. Like the helping hand extended to an exhausted swimmer, they may save from fatal sinking. Like the whip which is vigorously applied to the overtasked and straining street-car horses, when they falter near the summit of the hill, stimulants may impart an artificial strength which shall be sufficient to overcome the difficulty. But stimulants are goads. They do not nourish. They add nothing to the material from which permanent strength is derived. In health they are useless. The horse which can do its cus- tomary work only while under the constant appli- cation of the lash is really disabled by laziness or disease. And the person who resorts to alcoholic stimulants because he thinks that without their fre- quent goading he can not perform the drudgeries, or even the ordinary duties of life, is in a pitiable condition. If he be in health he is mistaken. Observation proves that, in the long run, more and better mental and physical work can be done ; hunger, fatigue, and long exposure to extreme cold or heat better endured ; and that the average health approaches more nearly a perfect standard without than with the habitual use of stimulants. Injurious. — But stimulants are injurious. Like the too powerful mainspring in a delicate watch, they produce strong and violent manifestations, but they wear out the works. The tendency of alcoholic stimulants — and these are the only ones now under consideration — is to impair the normal action of the various parts of the STIMULANTS AND NARCOTICS. 139 body, and even to produce serious organic disease. How this is accomplished is explained in various parts of this book. One of the saddest results of the use of these stimulants is a diseased craving, which can be satis- fied only by the further use of that which caused the craving and which intensifies it. Daily observation and abundant testimony prove that this acquired appetite may, and in numberless instances does, become almost irresistible, requiring increasing potations to appease its insatiable de- mands, and dragging down its helpless victims, through disease and loss of self-respect and blunted moral perceptions, and even crime, to utter ruin. If alcoholic stimulants are unnecessary, injuri- ous, and dangerous, should they not be avoided "> Is not the path of safety the path of wisdom ?* 2, Narcotics. These are substances which first exhilarate and then induce drowsiness or stupor. There are many of them, but two only will be noticed here : opium and tobacco. * As showing how the habit of using alcoholic beverages dimin- ishes the likelihood of recovery from serious illness, the following statement is of great value. It is from the report of the Investigation Committee appointed by the British Medical Association. The re- port was published in July, 1884. In 1,065 cases of pneumonia there were 192 deaths. The mortality of the temperate was 17 per cent. ; of the intemper- ate, nearly 43 per cent. ; while Of the total abstainers it was but ro per cent. I40 HO IV WE LIVE. The consumption of opium and its various prep- arations has greatly increased within a few years. While its continuous use does not seem to shorten materially the life of its devotees, it renders it miserable. It enfeebles the intellect, enervates the bodily powers, and gives a dull and vacant appear- ance to the face. Habitual opium-eating always weakens and perverts the moral sense. From its firm grasp its victims seldom escape. Their brief struggles for release become more and more im- potent, till finally the captivity is accepted as hope- less. Opium should be taken only when adminis- tered by a wise and prudent physician. Tobacco affects primarily the nervous system. It stimulates and it soothes. It seems to furnish great pleasure to those who chew or smoke it. But it has its drawbacks. Its habitual use impairs di- gestion, often causes palpitation of the heart, trem- bling of the hands, disturbance of the delicate bronchial tissue, and sometimes permanent injury of the nerves. Chewing is specially filthy. Smoking is offen- sive to a large proportion of the best people. Those who have abandoned the use of tobacco declare that they have sweeter breath, cleaner tongues, better digestion, steadier nerves, increased power of endurance, and a higher average of enjoy- . ment ; and that the loss of the fascinating excite- ment is more than offset by freedom from the result- ing depression. Should not a practice, however popular, which is filthy, offensive, hurtful, and expensive, be avoided ? WHAT THE WORDS MEAN. Ab-do'men (Latin, abdo, to hide). The largest cavity of the body, situated beneath the level of the diaphragm, and containing the liver, stomach, intestines, etc. ; the belly. Ab-sor'bents (Latin, ab and sorbeo, to suck up). The vessels which take part in the process of absorption. Ab-sorp'tion. The process of sucking up fluids by means of an animal membrane. Ac'id (Latin, acidtis, from acere, to be sour). A substance usually sour, sharp, or biting to the taste. Ad'am's Ap'ple. An angular projection of cartilage in the front of the neck. It is particularly prominent in males, and is so called from a notion that it was caused by the apple sticking in the throat of our first parent. Al-bi'no (Italian, albino, whitish). A person having a peculiar white- ness of the skin and hair, and a redness of the iris and pupil of the eye. Al-bu'men (Latin, albus, white). An organic substance resembling white of egg. Al-bu'mi-noids (Latin, albumen, and Greek, eidos, form). A class of substances resembling albumen ; they may be derived from either the animal or the vegetable kingdom. Al'co-hol (Arabic, al kohl, a powder to paint the eyebrows with). The intoxicating element of spirituous liquors. Al-i-ment'a-ry Ca-nal' (Latin, alimentarius, from alo, to nourish). A long tube, of varying form and size in its different parts, in which the digestion of the food, or "aliment," is performed. It com* pris€s the mouth, the pharynx, the esophagus, the stomachy and the small and large intestine. 142 WHAT THE WORDS MEAN. Al'ka-li (Arabic, al kali, the soda-plant). A name given to certain substances, such as soda, potash, and the like, which have the power of combining with acids to form salts. A-nat'o-my (Greek, anatome, cutting up, dissection). The study of the different parts and the structure of the body. Am'y-loid (Greek, amulon, fine meal, and eiaos, form). A substance similar to amyle, which is composed of ten parts of carbon and eleven of hydrogen. A-or'ta (Greek, aorteomai, to be lifted up). The largest artery of the body, and main trunk of all the arteries. It arises from the left ventricle of the heart. The name was first applied to the two large branches of the trachea, which appear to be lifted up by the heart. Ap-pend'age (Latin, ad, to, and pendeo, to hang). Something added to a principal or greater thing. A'que-ous Humor (Latin, aqua, water). A few drops of watery, colorless fluid occupying the space between the cornea and crystal- line lens. A-ro'ma (Latin). The agreeable odor of plants or other substances. Ar-te'ri-al Blood. The bright -red blood in the left side of the heart and the arteries of the general circulation. Ar'ter-y (Greek, aer, air, and tereo, to keep). A vessel conveying the blood from the heart outward to the organs ; so called because the ancients thought these vessels contained air. Ar-tic-u-la'tion (Latin, articulo, to form a joint). The movable union of bones ; a joint. Ath-let'ic (Greek, athleo, to contend for a prize). Belonging to wrestling, boxing, running, and other manly exercises and sports. Au'di-to-ry Nerve (Latin, audio, to hear). The special nerve of the sense of hearing. Au'ri-cle (Latin, auricula, the outer ear). The smaller and thinner chamber of the heart on each side, which receives the blood directly from the veins ; so called from a fancied resemblance in shape to a dog's ear. Au-to-mat'ic (Greek, automatos, self-moving). Self-acting ; not de- pending on the will. Bi'ceps (Latin). A muscle situated upon the front part of the arm above the elbow, which serves to bend the elbow-joint. Bi-cus'pid (Latin, bi, two, and cuspis, prominence). The name of the fourth and fifth teeth on each side of the jaw ; possessing two prominences. WHAT THE WORDS MEAN. 143 Bile. The gall, or peculiar secretion of the liver ; a sticky, yellowish fluid, and very bitter to the taste. Blonde. Of a fair, or light, color or complexion. Bone. A firm, hard substance, of a white or pale-rose color, compos- ing the skeleton or firmer part of the body. Brain. The mass of nervous substance contained in the cavity of the skull. Bron'chi (Greek, bronchos, the windpipe). The two larger branches into which the trachea is divided, and into which the bronchial tubes open. Bron'chi-al Tubes. The smaller branches of the trachea within the substance of the lungs, ending in the air-cells. Bru-nette'. Of a brown or dark color or complexion. Ca-Iis-then'ics (Greek, kalos, beautiful, and sthenos, strength). The practice of healthful exercise of the body and limbs, to give strength and grace of movement. Cal'lus (Latin, calleo, to be thick-skinned). Any excessive hardness ol the skin, caused by friction or pressure. Ca-nal' (Latin, canna, a pipe). In the body, any tube or passage. Ca-nine' Teeth (Latin, cams,^Aog). The pointed teeth situated just outside the incisors, one on each side in each jaw ; so called because they are very prominent in the dog, as well as in other flesh-eating animals. Cap'il-la-ries (Latin, capillus, hair). The smallest blood-vessels, be- tween the arteries and the veins ; so called from their minute or hair-like size. Car-bon'ic Ac'id (Latin, carbo, coal). The gas which is present in the air expelled from the lungs ; a waste product of the animal kingdom, and a food of the vegetable kingdom. Car'di-a (Greek, kardia, heart). The upper opening of the stomach, through which the food enters from the esophagus ; so called be- cause it is situated near the heart. Car'di-ac. Pertaining to the heart or to the cardia Car'ri-on (Latin, caro, flesh). The dead and decaying bodies of animals. Car'ti-iage (Latin, cartilago). A firm, elastic substance, like India- rubber, attached to the bones in various parts of the body, fonning a part of the joints, air-passages, nostrils, and ear. Cav'i-ty (Latin, cavusy hollow). A hollow, inclosed space. Ca'se-ine (Latin, caseus, cheese). The albuminoid substance of milk, forming the basis of cheese. 144 WHAT THE WORDS MEAN. Cer-e-bel'lum (Latin, diminutive of cerebrum, brain). The little brain, situated at the back and lower part of the head. Cer'e-brum (Latin). The brain proper, occupying the entire upper portion of the skull. It is nearly divided into two equal parts, called hemispheres, by a cleft extending backward from the front part of the head. Chest. The upper part of the trunk of the body, inclosed by the spinal column behind, the ribs on the sides, and the breast-bone in front. Cho'roid (Greek, chorion, skin, and eidos, like). A brownish-black membrane forming the middle coat of the eye-ball. Chyle (Greek, chulos, juice). Chyme changed in the duodenum, and turned white by the emulsion of fats. Chyme (Greek, chumos, juice). The pulpy liquid formed by digestion within the stomach. Cir-cu-la'tion (Latin, circulus, a ring). The circuit or course of the blood through the blood-vessels of the body, from the heart to the arteries, through the capillaries into the veins, and from the veins back to the heart. Clav'i-cle (Latin, clavis, a key). A slender bone, shaped somewhat like a key, placed horizontally at the bottom of the neck, between the top of the breast-bone and the point of the shoulder. The collar-bone. Col'lar-Bone. The clavicle. Con' cave (Latin, concavus, hollow). Curved or rounded, like the in- side surface of a hollow globe. Con-ges'tion (Latin, con, together, aud gero, to bring). An unnatural gathering of blood in any part of the body. Con-nect'ive Tis'sue. A tissue consisting of loose fibrous bundles, which is placed between the muscles and other parts. Con-sump'tion (Latin, consume, to take entirely). A disease of the lungs, attended with a fever and cough, and causing a gradual de- cay of the bodily powers. Con-trac'tion (Latin, con, together, and traho, to draw). The active shortening of a muscle or muscular fiber. Con'vex (Latin, conveho, to bring together). Curved or rounded, like the outside of a globe. Con-vo-lu'tions (Latin, convolvo, to roll together). The foldings of the external surface of the brain. Cor'ne-a (Latin, cornu, a horn). The transparent, horn-like substance WHAT THE WORDS MEAN. 145 which covers the front part of the eyeball, through which the light passes. Crys'tal-line Lens (Latin, crystallum, ice). A transparent, circular body, rounded on its front and back surfaces, situated in the eye- ball, just behind the pupil. Cus'pid (Latin, cuspis, a point). A . pointed tooth next back of the incisors. Cu'ti-cle (Latin, diminutive of cutisy the skin). The scarf-skin ; also called the epidermis. Cu'tis Ve'ra (Latin). The true skin, lying beneath the cuticle ; also called the derma. Dan'druff. The small scales, or particles, which separate from the scarf-skin of the scalp. De-lir'i-um (Latin). A state in which the ideas of a person are wild, irregular, and unconnected. Den'tine (Latin, dens, a tooth). The bony or ivory-like part of the teeth, lying directly beneath the enamel. Der'ma (Greek, the skin). The soft, moist, and thick underlying layer of the skin ; the true skin, or cutis vera. Di'a-phragm (Greek, diaphragma, a partition). The muscular sheet which separates the cavity of the chest from that of the abdomen. Di-ges'tion (Latin, di, apart, and gero, to bear). The preparation of the food in the alimentary canal. Dig'i-ti-grade (Latin, digitus, finger, and gradi, to walk). An animal that walks or steps on its toes. Dis-ease'. An unhealthy condition of some part of the body. Duct (Latin, duco, to lead). A narrow tube, usually designed to con- vey away a secretion from the gland in which it is produced. Du-o-de'num (Latin, duodeni, twelve each). The first division of the small intestines, about twelve finger-breadths long. E-las-tic'i-ty. The property of bodies by which they recover their former figure or size after the removal of outside pressure or force. £n-am'el. The dense material which covers the crown of the tooth. Ep-i-der'mis (Greek, epi, upon, and derma, skin). The outer layer of the skin ; the scarf-skin, or cuticle. Ep-i-glot'tis (Greek, epi, upon, and glottis'). A leaf-shaped piece of cartilage which covers the top of the larynx during the act of swal- lowing. E-soph'a-gus (Greek, oiso, to carry, and thago^ to eat). The tube 146 WHAT THE WORDS MEAN. leading from the throat to the stomach, through which the food and drink pass in eating. Ex-cre'tion (Latin, excernoy to purge out). The process by which the waste materials of the body are removed ; also the materials ex- creted. Ex'er-cise (Latin, exerceo, to keep busy). Effort or action of the body for the sake of training, or of keeping its organs and functions in a healthy state. Ex-pan'sion (Latin, ex, out of, and pando, to open). The act of ex- tending or spreading out. Ex-pi-ra'tion (Latin, expiro, to breathe out). The act of forcing air out of the lungs. Ex-ten'sor (Latin, ex, out, and tendo, to stretch). A muscle which serves to straighten or extend a joint. Eu-sta'chi-an Tube. A membranous canal, extending from the fore part of the tympanum of the ear to the side of the pharynx ; from Eustachi, an Italian anatomist, Fe'mur (Latin). The thigh-bone. Fi'ber (Latin, Jlbra, a thread). One of the string-like portions which constitute a part of the tissues of plants and animals. Fi'bril (diminutive of fiber). A very small branch of a fiber. Fi'brine (Latin, yf^nz, a fiber). An animal matter found in the blood; so called because, when clotted, it has a fibrous texture. Fib'u-la (Latin, that which serves to fasten two things together). The outer and smaller bone of the leg. Flex'or (Latin, Jlecto, flexum, to bend). A muscle which serves to bend a limb or joint. Flip'per. The broad fin of a fish. Forii-cle (Latin, diminutive of follisy a bag). A little pouch or de- pression in a membrane ; it has generally a secretory function. Func'tion (Latin, fimgor, functus, to perform). The office performed by any organ of the body. Gan'gli-on (Greek, ganglion^ a knot). A knot-like swelling in the course of a nerve ; a smaller nerve-center. Gas'tric (Greek, gaster, the stomach). Pertaining to the stomach. Gel'a-tine (Latin, gelo, to congeal). An animal substance which dis- solves in hot water, and forms a jelly on cooling. Gland (Latin, glans, an acorn). An organ consisting of follicles and ducts, with numerous blood-vessels ; it separates some particular fluid from the blood. IVHAT THE WORDS MEAN. 147- Glot'tis (Greek, glotia, the tongue). The narrow opening between the vocal cords in the upper part of the larynx, by which it com- municates with the throat. Glu'ten (Latin). Literally, glue ; the gluey, albuminous matter of wheat-flour. Gus'ta-to-ry Nerve (Latin, gustOy to taste). The nerve of taste sup- plying the front part of the tongue. Gym-nas'tics (Greek, gutnnazo, to exercise). The practice of athletic exercises. Hic'cough. A spasm of some of the muscles used in breathing, accom- panied by a shutting of the glottis and a sudden sound. Hu'me-rus (Latin). The large bone of the arm between the shoulder and the elbow. Hu'mor (Latin). Moisture : the humors are transparent contents oi the eyeball. Hy'gi-ene (Greek, huygieia, health). The art of preserving health and preventing disease. I-de'a (Greek, outward appearance). The complete conception of an object. In-ci'sor (Latin, incido, to cut). Applied to the four front teeth of both jaws, which have sharp, cutting edges. In-den-ta'tion (Latin, in, and dens, a tooth). A notch in the margin of anything. In-fe'ri-or Ve'na Ca'va (Latin, lower hollow vein). The chief vein of the lower part of the body. In-flam-ma'tion (Latin, prefix in, and flammo, to flame). A peculiar diseased condition of any part of an animal body. In-gre'di-ent (Latin, ingredi, to go into). That which enters into a compound as one of its constituents. In-spi-ra'tion (Latin, in, and spiro, spiratum, to breathe). The act of drawing in the breath. In-ter-cos'tal Mus'cles (Latin, inter, between, and casta, a rib). The muscles which are situated between the ribs, and which move the ribs in respiration. In-tes'ti-nal Juice. A sticky secretion produced by the lining mem- brane of the small intestine. In-tes'tine (Latin, intus, within). The part of the alimentary canal which is continuous with the lower end of the stomach ; also called the bowels. I'ris (Latin, iris, the rainbow). The thin muscular ring which lies be- 148 WHAT THE WORDS MEAN. tween the cornea and crystalline lens, and which gives the eye its brown, blue, or other color. Jaun'dice {Yrenchy jaujte, yellow). A disease in which the skin as- sumes a yellowish color, supposed to be caused by an excess of bile. Lac'te-als (Latin, lac, lactis, milk). The absorbent vessels of the small intestines ; during digestion they are filled with chyle, which has a milky appearance. Lar'ynx (Greek). The box of cartilage situated at the top of the windpipe, through which the air passes from the throat into the trachea ; the organ of the voice. Lens (Latin). Literally, a lentil ; a piece of transparent glass or other substance so shaped as either to bring together or disperse the rays of light. Lig'a-ment (Latin, ligo, to bind). A fibrous band or cord, serving to attach two bones to one another. Liv'er. The largest gland in the body, reddish in color, situated mainly on the right side, below the diaphragm. From the venous blood passing through it, it secretes bile. The liver produces from the blood an animal starch. Lobe. A round, projecting part of an organ, as of the liver, lungs, or brain. Loin. That part of an animal just above the hip-bone. Lu'bri-cate. To make smooth or slippery. Lung. One of the two organs of respiration in an air-breathing animal. Lymph (Latin, lympha, spring-water). The colorless, watery fluid conveyed by the lymphatic vessels. Lym-phat'ic Ves'sels. A set of very thin, delicate vessels, which absorb the lymph from the tissues of the body, and convey it in- ward toward the center of the venous system. Mac-a-ro'ni (Greek, fnakar, blessed). An article of food, composed chiefly of wheat-flour made into long, slender tubes, and much used in Italy. Mar'row. The soft, fatty substance contained in the central cavities of the bones : the spinal marrow, however, is composed of nervous tissue. Mas'se-ter (Greek, massaomai, to chew). A strong muscle situated upon the side of the face, which moves the lower jaw from below upward in chewing. WHAT THE WORDS MEAN. 149 Mas-ti-ca'tion (Latin, mastico, to chew). The act of cutting and grinding the food to pieces by means of the teeth. Me-dul'la Ob-lon-ga'ta (Latin). The "oblong marrow." or nerv- ous cord, which is continuous with the spinal cord within the skull. Mem'brane (Latin, membrum, a limb or member). A thin layer of tissue serving to cover some part of the body. Mi'cro-scope (Greek, mikros, small, and skopeo, to look at). An op- tical instrument which magnifies objects. Molar (Latin, niolay a mill). The name applied to the three back teeth of each side of the jaw, which are adapted for grinding the food, like millstones. Mo'tor (Latin, moveo, tnotum, to move). Causing motion ; the name of those nerves which conduct to the muscles the stimulus which causes them to contract. Mu'cous Mem'brane. The thin layer of tissue which covers those internal cavities or passages which communicate with the external air. Mu'cus (Latin). The sticky fluid which is secreted by mucous mem- branes, and which serves to keep them in a moist condition. Mu-ri-at'ic Ac'id. An acid consisting of one part of hydrogen and one of chlorine. Mus'cles (Latin, musculus^ a little mouse). A band of fibers acting as an organ of motion in animal bodies. The voluntary muscles act in obedience to the will, and contract suddenly ; the involun- tary muscles do not obey the will, and contract slowly. Nar-cot'ic (Greek, narkaoy to benumb). A medicine which, in poi- sonous doses, produces stupor, convulsions, and sometimes death. Na'sal (Latm, nasus, the nose). Pertaining to the nose ; the nasal cavities contain the special nerve of smell. Nerve (Greek, neuron^ a cord or string). A glistening, white cord, shaped like a tube, and connecting the brain or spinal cord with some other organ of the body. The nerves are the telegraph-wires of the body. Nerve-Fi'ber. A very slender thread of nervous tissue found in the nerves ; it is of a white color. Nos'tril (Anglo-Saxon, nosu, nose, and thyrl, a hole). One of the two outer openings of the nose. Nurt'ure. To train up with care ; the food and attention necessary to such training. I50 WHAT THE WORDS MEAN. Nu-tri'tion (Latin, nuUio, to nourish). The processes by which the nourishment of the body is accomplished. 01-fac'to-ry (Latin, olfacio, to smell). Pertaining to the sense of smell. O'pi-um. A narcotic drug obtained fiom the juice of the white poppy. Op'tic (Greek, opto^ to see). Pertaining to the sense of sight. Or'gan (Greek, organon, an instrument). Any part of the body which is adapted to perform a particular service, such as the heart, the stomach, the brain. Ox'y-gen (Greek, oxus, sharp, and genein, to bring forth). A gas forming one fifth part, by bulk, of the atmosphere, and essential to respiration. Pal'ate (Latin, palatum, the palate). The roof of the mouth, con- sisting of the hard and soft palate. Pan'cre-as (Greek, pas, pantos, all, and kreas, flesh). A long, flat gland placed behind the stomach; in the lower animals this organ is called the siveet-bread. Pan-cre-at'ic Juice. The secretion produced by the pancreas. Pa-pil'lae (Latin, plural oi papilla). The minute elevations in which terminate the fibers of the nerves of touch and taste. Pa-ral'y-sis (Greek, parahw, to loosen). A disease of the nervous system marked by the loss of sensation, or voluntary motion, or both ; palsy. Pa-tel'la (Latin, diminutive oi patina, a pan). The knee-pan. Pel'vis (Latin, a basin). The bony cavity at the lower part of the trunk ; the hip-bone. Per-i-car'di-um (Greek, peri, about, and kardia, heart). The sac in- closing the heart. Per-i-os'te-um (Greek, pe7i, around, and osteon, a bone). A fibrous membrane surrounding the bones. Per-spi-ra'tion {I^^XXvl, perspiro, to breathe through). The sweat, or watery fluid poured out from the skin ; when visible, it is called sensible perspiration ; when invisible, insensible perspiration. Phar'ynx (Greek, pharunx, the throat). The muscular passage lead- ing from the back part of the mouth to the esophagus. Phys-i-ol'o-gy (Greek, phusis, nature, and logos, a discourse). The science of the functions of living, organized beings ; the study of the natural actions of the living body. Pig'ment (Latin, /m^