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Entered according to the Act of the Parliament of Canada, in the year One Thousand Eight Hundred and Seventy-nine, by Edward Playter, M.D., in the Office of the Minister of Agriculture. The nec< structure anc of avoiding is very gene in the public expressed, f ally the yoi this want tl there are a [the public, general use, fold evidenc sede the ne( these impoi cian, to kno be familiar elementary to present, ; its environ n to touch upi attention ai familiar lau have, for th The auth amid the us of a health DUDLEY & BURNS, PRINTERS, TORONTO. Parkdai PREFACE. The necessity for much more wide-spread and universal knowledge on the structure and functions of the human body and the causes of disease and means of avoiding them and preserving the health is admitted by every one. And it is very generally admitted, too, that these subjects should be regularly taught in the public schools. A want however has been much felt and frequently expressed, for an elementary work, suited to the masses of the people, especi- ally the youthful portion, on the subjects of Physiology and Hygiene ; and this want the author of this little book has endeavored to supply. While there are a number of excellent works on the same subjects in the hands of the public, they are, for the most part, either too large or too technical for general use, or too elementary and incomplete. And besides, we have mani- fold evidence on every hand that their influence has not been such as to super- sede the necessity for another. In this the author has endeavored to give, on these important studies, about all that is necessary for any one, not a physi- cian, to know, yet not more than every girl and boy, without exception, should be familiar with before leaving school or completing education : from a more elementary work the requisite knowledge could hardly be obtained. In order to present, as clearly as is desirable, the human organization in its relatir ns to its environments, or to the essentials of life, the author has deemed it necessary to touch upon almost all parts of the subjects treated of, but he has given most attention and space to the most important and practical parts. Simple and familiar language has been used, though proper scientific names and terms have, for the most part, necessarily, been retained. The author desires critics to bear in mind that the book has been written amid the usual diities and interruptions of a practising physician and Editor of a health magazine. Parkdale, Toronto, 1st June, 1879. ELE ERRATA. Page lo, 7th line, for jelU-y, read jelly. M II, description of fig. 2, last word, for ^'vz/mlation, read ^^rt«u- lation. „ 25, 3rd line from bottom of next to last paragraph, for palmi?r, read palmar. „ 36, 5th line, for Chap, viii, read Chap. ix. M 81, 4th line, the letters t i have dropped out of the word diges- tion. „ 84, 3rd paragraph, 2nd line, the letter 1 has dropped out of the word lungs. HAPTER II II I II J II II II V II VI II ] M > II X M X II 1 J. II X II x^ II XV II X Questions Index . . CONTENTS. PART I. ELEMENTARY ANATOMY AND PHYSIOLOGY. JHAPTER d gran\x- ■ palmifr, id diges- ut of the I'AOK. L— Introductory:— Elements, cells, life, waste .... 7 Il.—Constituents, tissues, structure, and divi>ions, of tlu- human body '3 in. — The nervous system ^° IV. — The bones and joints 27 v.— Organs of motion— the muscles 34 VI.— Sensation:— Touch; taste; smell; hearing; seeing . 39 VII.— The blood and its circulation 49 VIII. — Respiration; animal heat and force; the voice . . . 65 IX. — Digestion and absorption 74 X. — Secretion and excretion . ■ °4 PART II. ELEMENTARY HYGIENE. ti XI.— Preliminary :— Health and disease ; causes of disease, insidious nature of ; value of hygiene 87 „ XII.— The air as regards health 9^ „ XIII.— Water as regards health ^°' „ Xi'V.— Food as regards health ^°7 „ XV.— Exercise as regards health ^24 „ XVI.— Rest and sleep in regard to health 131 M XVII. — Clothing as regard^ health '35 „ XVIII.- Bathing as regards health 14° „ XIX. — Recapitulation of the chief causes ol disease and how to avoid them ; and \vhat to do in cases of sickness and certain accidents '44 Questions ^ , Index . . ■ ELEME INTRC The 1 be dividec first, beloi everythini rocks, am ferent, co the foot c a definite bodies ar three stat and a thi an egg._ and a tin away, am Not-livin their pari not orgai Now — hands, s[)ecial u stantly w lungs, ar always t^ first of a' of flesh, IS made. of air, w phorus, : notice sc PART I. ELEMENTARY ANATOMY AND PHYSIOLOGY. CHAPTER I. INTRODUCTORY- ELEMENTS, CELLS, LIFE, WASTE. The living and the not-living. — All known objects may be divided into two great classes, living and not-living. To the first, belong all plants and animals, including man; to the second, everything in nature not included in the first, the air, water, earths, rocks, and other metals. All living objects are made up of dif- ferent, complete, more or less independent, parts, or organs^ as the foot or eye of an animal, the leaf of a plant, each part having a definite structure and a special use or office. Hence, all living bodies are organized and are called organic. They are found in three states or conditions : one, that of ///f what is eyes, or if agency of lind, and body, con- 1th mental the blood, ; preceded n or func- THE NERVOUS SVSTEM. 23 a message from one station to another. Suppose yourself to be lying on your back upon a lounge, and some one touches the skin of your foot with a feather, or a fly lights upon it, the contact of either with the skin, acting as a stimulus^ produces upon the numerous minute sensory nerve-filaments in the part touched, an impression ; this gives rise to some change in the molecules of the filaments, which change extends quickly along them up the nerve of the leg and thigh to a centre, the cord or brain, or both. What next follows depends somewhat upon circumstances. If your mind is particularly engaged, intent upon some other matter — if you are in deep thought, or sound sleep, you probably do no\. perceive that anything touches your foot ; though perhaps it may be withdrawn. But if your mind is not ]> irticularly intent upon something else, and you are awake when the change which commenced in the distant filaments in the part touched reaches, or is comm'.' 1 cited to, the brain, the impression is feii, — a sen- sation is expcilenced, — you become conscious that something has touched your foot. But what consciousness is, or how it is that anything so remarkable should result from touching or irritating nervous tissue, we do not know. Look at your leg as you lie there. It is a part of your body nd you can raise it off the lounge if you wish, if you loill to do 0. Suppose you do raise it. The first act in this, a voluntary iiovement (volo, to will), is a mental act, remember ; some change akes place in some point in the brain most intimately and directly onnected with the mind. This change or influence passes out land, your of the brain along motor nerve fibres, down the cord, down the arge nerve supplying branches to the limb, down the branches to the muscles of the thigh and leg, and in some unaccountable way auses the fleshy fibres of certain muscles to become shorter and, drawing on the bony levers, move the limb. It would prove that nerves convey nervous influence if he large nerve that supplies this iimb, the largest nerve trunk n your body, the sciatic, which is deep down in the flesh below moniously md behind your hip, were by any strange accident entirely cut I increased icross and no other tissue injured, and then some one were to this fluid ouch or even pinch the skin of your foot. You would not feel and the he pinch, you would have no sensation or consciousness that mything touched you, unless you were to see it plainly, and then to convey ^ou would hardly believe it. If you placed your own hand on ;he centres ^our leg, the sensation to your hand would be like that of placing re conveyspt on the leg of another person. If you willed, now, to raise your \h I 24 EI.EMEN'TARV ANATOMY AND PHYSIOLOGY. leg from the lounge you could not do so, by any effort of the will, — unless you lifted it with your hands or other leg, any more than you could raise a mountain. The mental act, the act of the will, takes place in your brain, but the medium of communication be- tween the brain and the muscles in the leg is severed, and the influence cannot pass the disconnected cut ends of the nerve any more than a telegraphic message can pass from one station to another when the communicating wire is cut in two. A condition of the limb very like this supposed one, you have probably experienced from sitting or lying in a certain position on a hard chair or bed, causing firm pressure upon this nerve for some time, and thus temporarily destroying its conducting power, when the whole limb gets into that peculiar state in which it is said to be * asleep,' — it is (]uite numb, and you cannot move it. When a nerve is injured, pain is experienced at, or refer- red to, the distant part in which its sensory fibres end ; as is un- pleasantly illustrated when one receives a blow upon the 7i/naf nerve, at the elbow, which gives rise to a disagreeable sensation about the little finger, where the sensory filaments of this nerve terminate. Functions of the spinal cord. — These are: — ist, that of conveying nervous influence to and fro between the brain and distant parts, through its white fibrous matter ; and 2nd, that of originating certain movements, in virtue of its cellular matter. Suppose, again, for example, you had the misfortune to have your spinal cord severely injured or cut across in the neck; you might continue to live, but all parts supplied by nerves arising from the cord below this point would be paralysed, numbed. You would not feel any touching or pinching of these parts ; you could not by any effort of the will move them. You might will to raise your leg or arm, but you could not, in the slightest degree. The mental act in your brain would take place, you would be conscious you were making an effort to move, but it could not avail. The great cable between the brain and the limbs would be broken. The function of parts supplied by nerves from above the injury would remain unchanged. You could move the muscles of your face, and feel anything touching the skin there. But to have sensation and voluntary motion in a part, it must have uninterrupted nervous connection with the brain. No mental act, no sensation, can take place in the cord. The involuntary functions, in these circumstances, it may here be observed, — digestion, circulation, etc., being presided THE NERVOl'S SYSTEM. 25 the will, lore than the will, ation be- and the he nerve e station yon have position nerve for ig power, ^hich it is move it. , or refer- as is un- the u/uar sensation his nerve st, that of brain and d, that of natter, le to have leck; you es arising numbed. ;se parts ; fou might e slightest Dlace, you )ve, but it 1 and the by nerves k^ou could iching the otion in a with the I the cord. :es, it may ? presided over by the sympathetic, and a pair of nerves from the brain (pneumogastric, see page 22), would probably not be interfered with for an indefinite time, and then only indirectly. If any one now, as you lay thus paralysed, were to prick the sole of your foot, the impression would cause some change to fly up the sensory nerve fibres ending at the point pricked, to the cord, and a mofor influence, originating in the cord, would perhaps be returned from it back along motor fibres to the mui>cles of the limb, which would contract and draw the foot away. You would be quite unconscious of the pricking, or of the subsequent move- ment, which indeed you would be unable to prevent if you tried. Such movements a^e called refltx^ — //^voluntary. A reflex action, then, is one which takes place in your body without your knowledge. These actions frequently originate in the cord or smaller ganglions. They are very important, and you should understand them ; they are continually going on in your body, especially in the organs of organic life. If the foot of one m a sound sleep were pricked, a reflex movement would likely take place, — the foot would probably be withdrawn, without the consciousness of the sleeper. Neither connection with the brain, therefore, nor consciousness, is necessary for such actions. A double stimulus is required for the perfect development of some movements, and the mental effort is assisted by this reflex function of the cord. In walking, the pressure against the soles of your feet may give rise to sufficient reflex action for main- taining the upright posture, while the harmonious movements required for progression originate in the brain. The most firm hold may be obtained upon that object which best adapts itself to the palmer surface of your hand, and thus, pressing upon the largest number of the sensory filaments ending there, gives rise to the most reflex action. Reflex actions arise in the brain, especially in the me- dulla. The closure of the eyelids by a threatened blow, or the 'starting' at a loud noise, are reflex actions. When you read aloud, a vast number of delicate but unconscious reflex actions go on. The book is held in the hand, at proper distance from the eyes, these are moved from side to side and down the page, while most delicately adjusted and rapid movements of the lips, tongue, and chest take place ; you may be standing, and accom- panying the words with appropriate gestures; yet all these actions are performed with utter unconsciousness on your part of anything but the subject-matter of the book. 26 ELEMENTARY ANATOMY AND PHYSIOLOGY. An artificial or acquired reflex action is one which, after having been frequently repeated consciously, becomes, as it were, a part of your organization, — a ' second nature,' and is per- formed without an act of the will, or even without consciousness. A well-drilled soldier will perform, instantly, at the mere sound of the word of command, and without thought, certain acts in which he has been well drilled. Education is largely based upon the existence of this power possessed by the nervous system, of thus organizing conscious actions into those which are more or less unconscious or reflex. Functions of the brain. — These are not so well understood. The medulla appears to be the centre of the involuntary move- ments necessary to breathing and swallowing. Other ganglions in the under part of the brain are centres of the senses of seeing, liearing, etc. They receive impressions from the special organs of these senses, as the eye and ear, with which they are connected by sensory nerves, and inform the mind of the nature c hese impressions. It is believed to be the work of the lessei .rain to harmonize, or co-ordinate, muscular movements. Animals deprived of it are unable to so combine the actions in different sets of muscles as to be able to assume or maintain any attitude. The intellect and the convolutions— that thick folded sheet of grey cellular matter forming the whole outer part of the greater brain, are most intimately connected. Without doubt the convolutions are the centre of intellectual action. Every idea, every thought, however simple, is associated with a corresponding change in some part of this broad surfiice. It is the great recep- lacle m which the various sensations become perceptible to the animal. Here all sensations take a distinct form and leave last- ing traces of their impressions. It is a * seat to memory,' by which we are furnished with materials for our judgments. As proof of the above, the convolutions are but very imper- fectly developed in infancy, and the increase in mental capacity is simultaneous with their further development. If anything arrests their growth, the mental powers remain of the feeblest kind ; and they are very imperfect in idiocy. Furthermore, we find a progressive increase in their development and complication, and in the extent of the convoluted surface, as we ascend from inferior to higher animals. They are not essential to life in ani- mals, and appear to be insensible to pain from injury. 1 THK HONES AND JOINTS. 27 ch, after s, as it d is per- oLisness. ■e sound acts in ed upon stem, of more or ierstood. :y move- glions in f seeing, )rgans of )nnected c hese iCi ..rain Animals different attitude, k folded t of the oubt the ixy idea, .ponding xt recep- ile to the jave last- lory,' by y imper- capacity anything feeblest more, we plication, ind from fe in ani- CHAPTER IV. THE BONES AND JOINTS. The original design of bone seems to have been that of pro- tecting the softer tissues, or more vital organs. Some of the lower animals are almost completely encased in dense bone. Only the essential or most vital organs in man are so protected ; while bones give him a fixed form and serve other purposes. Composition of bone. — Bone is, simply speaking, cartilage infiltrated and hardened by lime salts, — chiefly phosphate and carbonate of calcium (page 13). In children, the cartilagi- nous matter predominates, and their bones will bend rather than break ; while in the aged, the lime salts are in excess, and the bones are brittle. If, for example, you immerse a slender bone in dilute hydrochloric acid — one part of acid to about ten of water — in a few days the acid will dissolve all the mineral matter, leaving a gristly model of the bone, so soft and flexible that it may be tied in a knot. By placing such a bone in a clear fire for a little time, the cartilaginous matter will be all burned out, and the remaining lime salts may be almost picked in pieces with the fingers. Fi''. 10. I'iy. 11. Transverse section of bone, showuij,' two of the canals with the cavitie.s (the dark spots) and pores arranged coneentically around them (highly magnified). Longitudinal section of hone, sliowini; canals and their branches and the cavities and pores (less magnified than Fig. 10). The structure of bone is illustrated in Figs. lo, ii. The tissue is traversed throughout by a system of minute tubes, or canals^ which contain the blood-vessels for carrying nutrient mat- ter into the bone. Around and between the canals are minute 28 ELEMENTARY ANATOMY AND PHYSIOLOGY. irregular cavities, from which radiate numerous branches, or pores. that unite with the pores of other cavities. The cavities and jjorous ramifications are apparently apertures left in the bony matter, and as they are usually arranged in concentric zones around each canal, bony tissue has the appearance of being arranged in thin circular layers around the canals. In the long bones of the extremities is a large cavity, nearly as long as the bone, containing fatty tissue and blood-vessels, called marro7v. The ends, or extremities, of these bones being usually enlarged for the formation of joints, the tissue heie is more porous and lighter than that of the shaft. On the surface of many bones are certain depressions and projections ox processes. Some of these are designed for the better construction of joints \ while to many of the processes muscles are attached. The broad flat bones, which enclose cavities, especially the cranial, consist of two thin but dense plates, or tables, separated by a spongy structure ; this gives lightness with strength. A thin membrane (periosteum) closely invests bones, and the central cavities are lined by a similar one. In these the blood-vessels subdivide into minuter vessels, which enter the little canals in the bone. If any part of these nutrient membranes covering a bone is destroyed, death of the bone beneath results, as the blood supply is thus cut off. Marks and features similar to these on human bones, you will find if you look for them on the bones of domestic animals. In the * round ' of beef-steak you have a transverse section of the large thigh-bone of the ox, with its large central cavity, filled with mar- row. The chief depressions and projections, the enlarged extre- mities for joints, and the membranes, you will find on the bones of a lamb or even a turkey. Number and variety of bones.— The entire bony frame- work is called the skeleton. No one of the domestic animals has an entire skeleton closely resembling that of man, but Fig. 1 2 is a good representation of it. The number of bones in it varies a little with age; in the adult there are two hundred distinct bones, l)esides the thirty-two teeth, three minute bones in each ear, and eight small osseous masses near certain joints. They may be classified as follows : — s''""!^."""":::::::::;:;::;:;::::::::::;::::::::::::,* Trunk, including neck 52 Upper extremities — right and left 64 Lower extremities, with hip bones, right and left 62 200 ■L or pores, ities and the bony ric zones of being :y, nearly d-vessels, les being J heie is e surface processes. )f joints j daily the separated nes, and .hese the the little ' embranes 1 results, , you will nals. In . ' the large rt'ith mar- ked extre- he bones ny frame- imals has g. 12 is a t varies a ict bones, ear, and y may be . 8 . 14 . 52 . 64 . 62 200 " Fie 12 Fig. 12. — The skeleton. Pt, parietal bone ; Fl, frontal bone ; Tl, temporal bone ; O, occipital bone ; M, M, upper and lower raaxillaries, or jaw bones ; S, S, spine ; C, clavicle, or collar bone ; H, humerus, or arm bone ; H, radius ; U, ulna ; Sa, scapu- la, or shoulder-blade ; St, sternum ; R, R, riba ; P, pelvic, or hip bones ; Fa, femur, or thigh bone ; T, tibia ; F, flbula. Figs. 13 and 14. —Vertebrae, or spinal bones ; first one, side view ; second one, viewed from above ; B, body ; S, spine. Fig. 15.— Sternum, or breast bone, show- ing costal cartilages, C, between it and the ribs, K. i THE HONKS AND JOINTS. 29 Sa In your head it is ihe/ro/ifa/ bone which gives prominence to your forehead, and it is prominent as the front of your brain is prominent. The tiasa/ bones give prominence to your nose, and the malars to your cheeks. The upper and Xowtx jaiv bones (superior and inferior maxillary) carry the teeth ; the lower one only having a movable joint. The eight bones forming your b'"ain-case are as it were dove-tailed together^ forming immovable joints (sutures). In the skull of any domestic animal, just where it joins the backbone, you will find a large rounded opening. Through this the spinal cord passes ; it is the opening into the spinal canal, to be noticed presently. If you pass a pen-handle through the opening you will find it leads into a large cavity, the cranial cavity^ filled during life with the brain. There are, you may observe, several smaller openings in the floor of this brain case, through which nerves pass out, and blood vessels enter to supply the brain freely with blood. There are like openings (foramen) for like purposes through the bones of your own head. The back bone or spine, (vertebral column)^ supports the skull. Your spine is not all in one piece ; if it were you could not bend your back. But it is built up of twenty-four small, round- ish, flat pieces of light porous bone, called vertebrce (Fig. 13), — joined together one on top of the other, in the natural state, with intervening, connecting discs of cartilage, — and a triangular bone, the sacrum, upon which the vertebrae rest. Each vertebra has, ex- tending back from the rounded part, or body, two flat dense pro- cesses of bone, which, with the body, form a sort of ring (Fig. 14), and unite behind in a spine. When the column is built up, these rings form a continuous canal for the spinal cord. Little open- ings between the vertebrae permit the passage of nerves. The large opening in the skull is, in life, directly over the upper end of this canal, which is then continuous with the cranial cavity ; both being filled with nerve tissue, the brain and cord. The spine is not straight, as you may see (Fig. 12), but forms curves, which add to its elasticity ; and thus it assists in protecting the brain from the effects of jars in the acts of running and leaping. It supports the head and also the upper extremities or limbs and most of the trunk. The ribs, twelve half-hoops of bone on each side, are fastened to the spine behind j and in front, excepting the two last (floating ribs)y to Xht breast bone {sternum) by intervening cartilages (Fig. 15). In the upper extremity is the shoulder-blade (scapula), a flat triangular bone, somewhat loosely held in position, at the 30 ELEMENTARY ANATOMY AND PHYSIOLOGY. outer and back part of your chest, by fleshy attachments chiefly, which afibrd the arm a great degree of motion. At its upper and outer angle is a shallow cavity into which the rounded head of your arm-bone is received, forming the shoulder joint. Near this, the shoulder-blade is attached to the outer end of the collar- bone (clavicle)^ which keeps your shoulder in position and prevents it pressing on your ribs. In your arm (above elbow) there is only one bone (humerus) ; in your fore-arm (below elbow) there are two (radius and ulna). There are eight small bones in your wrist, and nineteen in your hand. In the lower extremity, the irregular, flairing hip bones (mnominaice) approach each other behind and support the spine. In each of the bones forming the hips is a deep, cup-shaped cavity, which receives the rounded, prominent head of the thigh- hone (femur), forming the hip-joint. The thigh-bone is the longest and largest bone in the skeleton. Below it, in the leg, there are two bones (tibia and fibula ), as in the fore-arm, and in I he foot, 26 bones. Functions of the bones. — For affording protection to the delicate nervous tissue, the bones of the cranium are most admirably adapted, in form and structure. You may receive a hard blow upon the head and your brain be uninjured thereby. * When we reflect on the strength displayed by the arched film of an egg-shell, we need not wonder at the severity of the blows which the cranium can withstand.' The spongy structure between the two plates of dense bone tends greatly to lessen the shock to the brain from a blow ; the outer plate may even be broken and the inner one not at all injured. The organs of sight, hearing, and smell are greatly protected by bone; as is the spinal cord, too, in its most admirable bony, but flexible sheath. So, also, are the great organs of supply and waste, by the flexible ribs and breast bone and the spine and hip bones. Bones form the frame of the body, giving it a fixed form and supporting other tissues. The skeleton indeed is a most wonderful piece of mechanism, combining perfect symmetry with the greatest freedom of motion. In the extremities, the long bones being hollow cylinders, are best adapted to support weight and resist violence. Bones form levers and fixed points to which the muscles are attached. But in order that you may understand how they form levers, it is necessary for you to have some knowledge of the different kinds of levers. A lever is an inflexible bar, movable on a prop or support, called the fulcrum, which is absolutely or relatively fixed. The lever is point oi motion 1 or weigh the fulcr the pow weights :vv The upp< mode of act The lowe F, fulcrum There second, a crum, th represen other, ai ground, ing the beneath of this ] The rais cles at ' being at ding yo the pow sented > The sim the toes the fulc: its chiefly, ipper and head of It. Near he collar- i prevents re is only there are '^our wrist, hip bones the spine, ip-shaped the thtgh- le is the 1 the leg, in, and in iction to oium are Du may uninjured d by the i severity £ spongy greatly to Diate may he organs ine ; as is t flexible te, by the p bones, xed form s a most lelry with the long irt weight joints to you may 1 to have support, ;d. The THE BONES AND JOINTS. 31 lever is used by causing some force, or power^ to act upon one point of the movable bar for the purpose of communicating motion to another point of it, in order to move some resistance or weight. In the arrangement of the bony levers in your body the fulcrum is usually at a joint ; the muscles in acting constitute the power ; while the various parts of the body are treated as weights (Figs. 16, 17, 18). Fipr. 16. Fisr. 17. Fig. 18. A- The upper three flaures represent the three kinds of levers; the first illustrating tin- mode of action in two directions, the fulcrum being supposed to be fixetl. The lower figures represent the foot when it takes the character of each kind of lever. F, fulcrum ; P, power; W, weight or resistance ; M. muscle, affording the power. There are three kinds or orders of levers, called first, second^ and thirds according to the relative positions of the ful- crum, the power, and the weight. A lever of the first order is represented when the power is at one end, the weight at the other, and the fulcrum between. If, when your foot is off" the ground, you raise your heel by contracting the muscles form- ing the calf of your leg (the power), as in pressing something beneath your toes (Fig. 16), you give an example of the action of this kind of lever, the ankle-joint representing the fulcrum. The raising of your face (the weight) by the contraction of mus- cles at the back of your neck is another example, the fulcrum being at the joint between the skull and spine. Again, in nod- ding your head, the same is exemplified, but the weight and the power are reversed. A lever of the second order is repre- sented when the weight is between the power and the fulcrum. The simplest example of its action is the raising of the body upon the toes by the action of the muscles of the calf, the ground being the fulcrum; as in standing on tiptoe (Fig. 17). When the 32 ELEMENTARY ANATOMY AND PHYSIOLOGY. power is between the weight and fulcrum the lever is said to be of the third order. When your foot is off the ground, and you raise your toes by means of muscles on the front of your leg, you exemplify the action of a lever of this kind (Fig. i8). Thus, the same part of your body, in different circumstances, may represent the three kinds of levers. When you have a bet- ter knowledge of the muscles and their actions you will more readily understand, and be able to think out for yourself, other examples in your body of the different kinds of levers. You will also then better understand how bones furnish fixed points for the exercise of muscular i)Ower OF THK JOINTS. Vou need hardly be told that, if your bony framework were made of one bone instead of two hundred, you would be like a piece of statuary and could not move. But as it is made up of so many pieces, joined together, you have in your body many Joints, or articulations. If each of your fingers instead of con- taining three short bones joined together, contained only one long bone, you would be unable to close your hand. In shutting your hand tightly, many joints, about fifteen, are brought into use. But joints are not all movable. In the cranium they are unyield- ing. Most joints however permit movement, varying in degree, from slight elasticity, to that of the shoulder -joint, the most mova- ble of all. So the joints form an interesting and important study. The tissues of movable joints are : — ist, cartilages. which form a smooth elastic covering for the opposed ends of the bones; 2nd, synovial membranes, small serous sacs (page i6) svhich line the civities of many joints, and contain a fluid, the synovia, for preventing friction ; and 3rd, ligaments, strong, flexible, fibrous straps, which stretch across the joint from one bone to the other and retain them in position. In the figure of the skeleton (Fig. 1 2), ligaments are represented at the joints of one side. They will be easily recognized in the joints of the leg of most animals. In some joints the bones are firmly united by an intervening disc of slightly elastic cartilage, permitting but slight movement. Of this sort are those of the spine, to which, however, as a whole, these joints give considerable /?>^ Section of ;inn bone ; I )cket of th< li|,'anients ; {posterior li the arm is s is bent. A ba face of permits directior The hip- cavity, shoulder and in it The of the Is floor of the com the opp( the forw In rotat, like pro( a pivot, aid to be and you r leg, you Tistances, ive a bet- will more >elf, other You will points for ork were be like a ade up of Ddy many d of con- only one a shutting into use, e unyield- in degree, lost mova- ant study. cartilages, nds of the 1 6) Nvhich le synovia, >le, fibrous i the other eton (Fig. tde. They >t animals, ening disc nent. Of ) a whole, ; — Flexion 'imduction. I, it is ex- )ody, it is THE BONF.S AND JOINTS. 33 dhducted ; adducted when moved toward the centre. It is rotated when made to turn more or less on its own axis ; and circumducted when the distant end of a limb is made to describe a circle without moving the trunk. The hinge-joint permits the movement of bones upon each other in two directions only, — forward and backward, — flexion and extension. The cylindrical head of one bone fits into a corres- ponding socket upon the other. The most perfect example of this form of joint is that of the elbow (Fig. 19). The knee and ankle-joints and those of the fingers and toes belong to this class. Fijr. 10 .Section of the elbow joint ; A, .sliaft of huincnis or ;inn bone ; B, its cylindrical bead, fittiiiir in the I )cket of the ulna, tlie inner forcann bone, C ; D, 1), Hi)) joint ; A, part of liip or ;)e/ei ■ li|,'ament8; that below, at the back of the elbow bone; B, cup-shaped cavity; 1), {posterior lxgav\ent), is folded, as in tlie figruro, when rounded, prominent head of fenuir or the arm is straight, and become strai^'lit as the arm thi<,'h-bone, C, drawn out of the ca- js bent. vitv; E, interarticular lirfaim'nt. A ball-and-socket joint is formed when a spheroidal sur- face of one bone plays in a cup-shaped cavity in another. It permits all the above movements ; — motion may take place in any direction, the extent of it depending on the de/^tli of the cavity. The hip-joint is a perfect example of this articulation with a deep cavity, and motion in it is somewhat restricted (Fig. 20). The shoulder-joint is an example of the same with a shallow cavity, and in it the most varied and extensive movements are permitted. The cranio-spinal articulation is peculiar. On each side of the large opening for the passage of the spinal cord in the floor of the skull, is a smooth, convex, oblong prominence, called the condyle, which rocks on a smooth, concave facet on the opposing surface of the first vertebra, the atlaSy and admits of the forward and backward movements of the head, as in nodding. In rotating the head, the atlas (first vertebra) plays round a peg- like process on the body of the second vertebra, the axis, as upon a pivot, an(J this is called a pivot-joint The body of the ^4 ELEMENTARY ANATOMY AND PHYSIOLOGY. atlas being small, the opening or ring is large and oblong, and divided into two by a strong fibrous band, or /i[i;;amenf, stretch- ing across the opening, behind the pivot, and the spinal cord passes down behind the ligament. Two c/iec/i ligaments prevent excessive rotation of the head. A second example of a pivot, joint exists at the upper articulation between the two fore-arm bones, at the elbow. chaptp:r v. ORGANS OF MOTION— THE MUSCLES. Structure of muscle. — The muscles are the flesh. They constitute the great bulk of the body, and bestow upon it form and symmetry. The 'round' of beef and the leg of lamb are nearly all muscular tissue. It consists of fine thread-like fila ments, ox fibres, arranged in small bundles (fasciculi) ; a number of these united together with connective tissue form a muscle. The muscular fibres of animal life, those controlled by the will, called voluntary fibres, which form the bulk of the body, are in man about j?;^ of an inch in diameter. When examined with a pow- erful microscope, they appear as if composed of rectangular cells. Each fibre may be split into a great number of most minute threads, ox fibrils, which may sometimes be divided transversely into discs (Fig. 21). The sides of muscular fibres are more or less flattened from being packed closely together ; and each is enclosed in a very delicate, transparent, but tough, elastic sheath (Fig. 22). Minute blood-vessels and nerves are plentifully dis Fijj. 21. Fitf. 22. Sliort piece of muscular fibre with much less bulky tendonous fibre attached (highly magnified). Fragments of rujjtured muscular fibre, I held together by the untorn but twi8tcil| sheath. tributed in muscular tissue, running in the angles between ihel fibres. The muscular fibres of organic life, which form layers in I blong, andl nt, stretch] pinal cordl Its preventl Df a pivot! 3 fore-arnil ish. Theyl Don it forml f lamb are! id-like filal a numberl muscle. 3y the will,! are in man) vith a pow- gular cells, ost minute ransversely e more or xid each is istic sheath itifully dis iiuscular fibre, I rn but twisteill etween ihel m layers in Fig. 23. The muscles. A, orbicularis pal)iebra- runi, surroumling the eye ; B. orbicu- laris oris, surround- ing the mouth ; C, masseter (to chew); D, outer, front mus- cles of neck ; F, su- pinators (turn out or back) of fore arm, and extensors (stretch out or open) of wrist and fingers ; G, pronators (turn in or down) of fore- arm, and flexors (ben- ders) of wrist and fin- gers. le walls itructure Attacl (ions, V0I1 by both ( I bone th s attache^ ivhite, ine Tendc ing much tthere mi ;ion of jo )eing attj inner side on the pa firmly clo of muscle forced ba( Muscle examine i hardly mi There body ; so rounded, muscles i muscular With few of each j There arc your exti upon the the other: at the ba( fibreslf^x liquely b( Three pa ina/) sun cavity; b( to the hij fibres pas ly, and w its contei ORGANS OF MOTION — THE MUSCLES. 35 he walls of the intestines and blood-vessels, are more simple in itructure than the other variety. Attachments of muscles— tendons— With few excep- ions, voluntary muscles are attached, either directly or indirectly, by both ends, to bone. Usually, one end is directly fastened to 1 bone that is absolutely or relatively fixed ; while the other end s attached to a movable bone, and through the intervention of a white, inelastic, fibrous band or cord, called a tendon. Tendons are much smaller and denser than muscles, occupy- ing much less space (Fig. 21). They are therefore employed fthere muscle would be too bulky for free motion, as in the re- gion of joints. They usually pass over one or more joints before )eing attached to bone. The tendons of tlie muscles on the nner side of your fore-arm you may readily feel, as dense cords, on the palmer surface or front of your w-ri^t when your hand is rmly closed and your \\x\'=X flexed ; and those of the outer group of muscles, on the back of your hand when this is opened and forced back. Muscles and tendons, and their connections, you may easily xamine in a leg of any of the domestic animals ; and you can liardly mistake them for any other tissue. There are about five hundred distinct muscles in your body ; some very small, others very large, some broad, others rounded, and a few forming a circle or ring. Many of the principal muscles are shown in Fig. 23. Besides, there are layers ot muscular fibres in the vvalls of the intestines, blood vessels, etc. With few exceptions, the five hundred are arranged in pairs, one of each pair being on each side of the middle line of your body. Tliere are over fifty muscles belonging, in their actions, to each of your extremities or limbs ; nineteen being in the hand, acting upon the fingers. Over thirty pairs are connected with your head ; the others are in the trunk. There are a large number of muscles at the back, connected with the spine. Two layers of muscular ^\>\QsXexternal and internal mtercostais, eleven pairs) f^vtend ob- liquely between the adjacent ribs, and move the ribs i^ b-eathing. Three pairs of broad muscles {external^ middle^ and internal, abdom- inal) surround, and form the bulk of the walls, of the abdomiPial cavity; being attached above to the ribs, behind to the spine, below to the hip bones, and in front to those of the opposite side. Their fibres pass in three different directions, crossing each other oblique- ly, and when they act they lessen the size of the cavity, pressing on its contents A broad, thin, somewhat circular muscle (the dia- h 36 ELEMENTARY ANATOMY AND PHYSIOLOGY. I I I I phragm or midriff)^ with its circumference attached to the ribs and spine, separates the abdominal, from the thoracic cavity. Its centre arches up deeply into the chest when at rest, and when acting it presses on the organs in the abdomen, and increases the capacity of the chest. (See Fig. illustrating nutrient organs, chap. viii). Functions of muscles— mode of action. — The special use of the muscles is to produce motion. Every act, from running and leaping to closing the eye or even to slightly varying the expression of the features, from wielding the heavy sledge of the smith to the most delicate stroke of the artist upon canvas, is produced directly by muscular fibre ; and this simply by their pro- perty of shortening, called contractility. But besides this special function, muscles enclose cavities, as described above, forming protective walls ; they assist in keeping joints in position ; and they give bulk and symmetry to the body. How do muscular fibres produce motion? By means of a power which each fibre possesses of shortening itself. When a muscle becomes shorter, it necessarily brings its two ends, with whatever is fastened to them, nearer together. They are so ar ranged that they act upon the various levers formed by the bones, and in thij way they give rise to nearly all voluntary movements. Circular, or orbicular, muscles surround the orifices of the body, and when they act, the size of the orifices is diminished, as ini puckering the lips. The property of shortening of muscular fibre differs en tirely from that byl which elastic substan I ces contract after hav- ing been stretched, and is called musciX lar contractility. The! lengthened condition! of muscle is the na[ tural one, the condi tion of rest, and thJ shortening can onlvj be continued a cer tain length of time In shortening, musi cles increase in other! dimensions, beconij ing thicker, and thtj If you place your right hand! Bones of the tipper extremity, with the biceps miisole, A, and triceps, C ; B, the "PPer and outer angle of the scapula or shoulder-blade. The fine lines at the biceps show the form of the mu.scle wlien it has contracted and drawn the hand up near the shoulder, as represented. actual volume remains the same ORGANS OF MOTION — THE MUSCLES. 37 enmg, mus on the front of your left arm, midway between the shoulder and elbow, and flex or bend the arm at the elbow, you will feel the flesh under your hand swell or rise up and become harder. This mass of flesh is the biceps muscle, and it is the shortening of it, as it swells out, which bends your arm. Its lower tendon is attached to the outer bone of the fore arm — the radius, just below the elbow; whtn this bone is pulled on by the muscle, it forms, with the inner bone, ulna, a lever of the third order, working at the elbow joint, on the lower end of the arm bone, or humerus, as a fulcrum, the hand representing the weight (Fig. 2<). This shortening is caused by some influence conveyed from your brain by the nerve fibres extending from the spinal cord and distributed in the muscle. By the exercise of your will, some change takes place in your brain, some influence is started there, which passes to the spinal cord, leaves the cord and picks its way among the bundles of delicate nerve fibres which pass from the upper part of the cord to the arm, until it reaches the biceps muscle. The muscle, directly this influence reaches it, contracts, becoming shorter and thicker, and by means of its lower tendon, pulls at the radius, and bends the arm. Hence, if the nerve which supplies your biceps muscle were severed, you could not shorten it, or bend your arm. You would do well now to turn back and read over page 23. When you wish to leave off" bending your arm, the influence dies away in your brain, and also in the cord and nerve fibres, and the muscle, no longer thus influenced, ceases to contract and pull on the radius, and the fore-arm falls by its own weight ; the arm becomes straight, and the muscle is drawn to its former length. Nearly all muscles act upon levers formed by the bones. A few examples were mentioned on page 3 1 ; the action of the biceps, above explained, is another example. In the forward and backward movements of the head upon the first spinal bone, as the fulcrum, representing the action of a lever of the first order, the power and weight are reversed according to circum- stances. When the face is depressed, the sterno-mastoid, in front of the neck (Fig. 23), represents the power ; when the face is raised, as a weight, the trapezius^ at the back of the neck, represents the power. The movements of the body upon the heads of the thigh bones furnish examples of the same sort of lever. When the thigh is raised by the rectus muscle (Fig. 23), the lower k 38 ELEMENTARY ANATOMY AND PHYSIOLOGY. tendon of which is attached to the leg bone (tibia) beyond the knee joint, the action of a lever of the second order is represented, the fulcrum being at the hip joint. And when the leg is extended and the foot thrown forward as in the act of kicking, by the same muscle and others on the front of the thigh, the thigh being a little raised, the movement represents the action of a lever of the third order. Again, when these muscles have their fixed point below, they steady the thigh aiid trunk upon the leg at the knee joint, the fulcrum ; also exemplifying a lever of the third order. There is great loss of power in the adjustment of muscles, and extent and velocity of motion, and beauty and adaption of form, are in many cases only obtained by such loss. In bending your mm, for example (Fig 24), by the shortening of the biceps one inch, yotjr hand is moved in the same period of time through the extent of twelve inches ; but the movement requires the mus- cle to exert twelve times as much force as would be necessary if its lower end were attached to the hand instead of near the elbow. It would be most inconvenient however to have the muscle ex- tend like a bowstring from your shoulder to your hand. Many muscles have antagonists. For example, the tri ceps, on the back of the arm (Fig, 24), is antagonistic to the biceps, and extends the arm after it has been flexed by the biceps, as in striking a blow with the fist. The fleshy mass on the inner side of your fore-arm consists of flexor and pronator muscles. The former flex the wrist and fingers, closing the hand ; the latter turn the palm inward toward the body. As you perform these acts, you will find these muscles become harder and swell out, showing that they contract. On the outer side of your fore- arm are the antagonists of these, which extend the wrist and fin- gers, opening the hand ; and also turn the palm outward. When antagonists act together, the part upon which they act be- comes fixed ; thus when the sterno-mastoid and trapezius in the neck act at the same time, the head is made firm, as in carrying a weight upon it. In this way fixed points are provided for the more efficient action of muscles in some movements. Muscles associate with each other in many actions. Indeed there are but few muscles which act entirely alone in j)roducing any movement or effect. In the animation of the features and in the act of swallowing, we have examples of the association of many muscles for the production of one effect. The muscular effort in standing is very considerable. II you stand constantly for a long time you are obliged to relieve THE MUSCLES. 39 one set of muscles by bringing another set into action. In order that any attitudes may be most easy, the centre of gravity or weight must be maintained within the base of support. For example, if when standing, one arm is raised, the equilibrium of weight is disturbed, and an inclination toward the opposite side becomes necessary. In walking and running the body is again and again forced forward, by muscular effort, beyond the base of support, and the base is brought again and again, also by muscular effort, under the centre of gravity of the body. In changes of attitude, in general, the more accurately they are effected, and the more eco- nomically in regard to the outlay of muscular power, the more graceful and pleasing are the movements and postures themselves. Tlie power of muscle may be increased wonderfully by regular use or exercise, and in this way men have become a le to display astonishing feats of strength. With increase in strength, muscles increase in size and firmness. Mere size however is not a positive criterion of strength ; for strength depends somewhat on the quality of the fibre, and also on the development and power of the nerves. This fact is sometimes overlooked, or not under- stood, and muscle is developed without due regard to the devel- opement of nerve. CHAPTER VI. SENSATION.— TOUCH ; TASTE ; SMELL ; HEARING ; SEEING. Sensation, as we have seen, is an affection of the mind, occasioned by an impression made upon a certain part of the nervous system (page 23). Sensations may be excited by causes arising within, or by causes without, the body. They may be divided into common and special sensations. Common sensation is referable to most parts of the body, and is that which ministers principally to the organic functions, and to the preservation of the organism. The feelings of comfort and discomfort, of faintness, fatigue, warmth, chilliness, nausea, and of hunger and thirst ; are common sensations. They are probably the results of affections of the sensory cranio-spinal nerves (page 21), arising through certain conditions of the various tissues in which these nerves end, or perhaps of the h'"^-^ 40 ELEMENTARY ANATOMY AND PHYSIOLOGY. blood, and however largely they may enter into the sum of our pleasures and pains, regarding the outer world they tell us nothing. The sensation of resistance, or the muscular sense, ex- perienced on lifting a weight, arises when anything opposes the movement of any part of the body, and is quite distinct from the feeling of contact, or touchy or even of pressure. Although not a very definite, it is a very delicate sense. The higher or special sensations are referable to five leading forms, to each of which is assigned a definite part of the body — a special organ. They are known as the sensations of touch, taste, smell, hearing and seeing ; and the organs adapted to receive the impressions which incite or give rise to these sensations, are, respectively, minute projections, called papilla^ in the skin, especially on the balls of the fingers, similar papilhe on the tongue, the membrane lining the nostrils, the .<;•, I .\S\Qeye. From these organs the impressions are conveyed by sensory nerves to the brain. These sensations are designed to inform the mind of the condition of things outside the body. In t, ~, to cv certain extent, they assist each other; the sense of seeing, for example, is aided by the sense of touch in determining the solidity of bodies. The stimuli which may excite three of these sensations — touch, taste, and smell, are various in character; while the sensations of hearing and seeing can only be awakened, under natural circumstances, by sound and light. SENSE OF TOUCH. — PAPILLAE. The sense of touch may be regarded as an exalted form of common sensation, which becomes very highly developed in some particular parts. It acquaints you with the degree of solidity of bodies and the nature of their surfaces, and thus educates the sense of vision. It is situated in minute, conical prominences, called papillae, which project from the surface of the cutis, or true skin, under the cuticle. Each contains a filament of a sensory nerve, and minute blood-vessels (Fig. 25). They are found all over the surface of the body, but much more numerously in some regions than in others. The greater the number of them in any part, the greater is its sensitiveness. You may learn the degree of tactile sensibility of the various parts of your body by placing the separated points of a pair of compasses in contact with the skin of the parts : where the papillae are numerous, a double impression may be recognized though the Thet chiefly o direction )lied wit urprise t chiefly si nucous I lelection linder p; Thef The sma mmerou; )apillae ith a pa I I SENSE OF TASTE, 41 m of our ; nothing, sense, ex- iposes the L from the ugh not a le to five art of the isations of he organs ;ive rise to ns, called ;rs, similar jstrils, the ; conveyed : designed the body, e sense of etermining *ee of these character ; awakened, points be very near each other ; while in parts where the papillae are few in number, the impression is of a single point though they may be far asunder. It has been found that the two points can be distinguished by the tip of the tongue if only -^ of an inch apart, and by the finger ends if ^ of an inch apart ; while if separated one inch on the cheek and three inches on the back, the points cease to be distinct. The balls of the fingers and thumb may be regarded as the organs of touch. Here the papillae are long, of large size, and very numerous. The soft cushion-like condition of these parts, caused by fat beneath the skin, is particularly favourable to the delicacy of this sense. Papillae are also numerous on the palmar surface of the fingers and hands, and on the soles of the feet, where the skin, as you may see, is finely and regularly grooved in various directions. The grooves are caused by the cuticle sinking into the interval between rows of papillae. In a square inch of the palm, about 250 papillae may usually be counted. The sense of temperature of bodies is distinct from that of touch, and is attributed to the nerves of common sensation. It is of a relative rather than of an absolute kind. For if one hand be dipped into hot, and the other into cold water, and both be then plunged into tepid water, this will appear cold to the hand taken from the hot water, and warm to the hand from the cold water. Again, the heat of warm water appears greater when the whole hand is immersed than when only one finger is dipped in it. SENSE OF TASTE. — THE TONGUE. The tongue, which is regarded as the organ of taste, consists chiefly of pairs of muscles, with their fibres extending in various directions, and an investment of mucous membrane, all freely sup- )lied with blood-vessels and nerves. Hence it is not a matter of iurprise that this is a most movable organ. The sense of taste is chiefly situated in papillae, similar to the papillae of touch, in the mucous membrane of the tongue, where it acts as a guide in the lelection of food. The sense also exists to some extent in the under part of the roof of the mouth, or palate. The papillae of the tongue are of two sorts, small and large. The small ones seem quite like those of touch, and are most numerous at the tip of the tongue. They are probably chiefly apillae of touch, as this sense is most acute in this region, which though thelvith a pair of compasses you can prove for yourself. The large ed form of )ed in some solidity of iucates the ominences, le cutis, or iment of a They are mch more greater the nsitiveness. the various )f a pair of the papilla 42 ELEMENTARY ANATOMY AND PHYSIOLOGY. papillae are most numerous at the back part or base of the organ, where the sense of taste is most acute, as you probably know from experience. It is in these that the filaments of the nerves of taste terminate. They are compound in form, having branch papillae upon their surfaces (Fig. 25) ; the sense of taste seemingly demanding a more complicated and delicate structure Fig. 25, Papillae. — A, grdup of papillse of palm, the cuticle being removed— magnified 3.5 times. B. compound papillee of mucous membrane of tongue, the larger one showing, on one side, its covering of epithelium (see page 15). C, blood-vessels of a papillaa. than that of touch. With the help of a looking glass you can see that the papillae on your tongue, if it is clean and healthy, are larger and more distinct than those on your fingers. It is a condition of taste that substances to admit of being tasted must be soluble in the fluids of the mouth, so that they may pass through the tissues of the papillae and come in contact with the nerve filaments ; which then convey to the brain the nature of the sensation produced. Taste may be greatly modi- fied by habit ; as indeed may all the special senses. Substances which at first are absolutely disgusting to the taste, become, through use, agreeable and even longed for ; as in the case of the filthy and vulgar habit of tobacco chewing, for example. If you abuse this sense, therefore, as by the use of tobacco, or too free use of condiments or ardent spirits, it will cease to be a reliable guide in the selection of food. Taste is intimately connected with the sense of smell, and some substances lose their taste when the nostrils are closed. SENSE OF SMELL. — THE NOSTRILS. In the nostrils, or nares, the sense of smell is located. The nostrils extend high up to the floor of the cranium or brain case ; and above and behind they open into the upper part ol the throat (or pharynx). They thus give free passage to tlie air we breathe, mn SENSE OF SMELL. 43 se of the probably Its of the [11, having e of taste ; structure magnified larger one -vessels of ou can see ealthy, are it of being that they in contact brain the tly modi- Substances J, become, case of the le. If you or too free i a reliable lected with e when the cated. The brain case ; )t the throat we breathe, and so enable us the most readily to detect odorous particles in it. Projecting from the outer wall of each nostril are three scroll- like, spongy {turbinated) bones, which partly divide the cavity into three passages, extending from before backward (Fig. 40). These, and also the partition [septum) between the two nostrils, are lined with a delicate mucous membrane — Schneiderian membrane. This membrane is very freely supplied with blood, in minute, delicate vessels, probably for the purpose of promoting warmth. Hence it bleeds, and sometimes very freely, from slight violence or injury, and then we say the ' nose bleeds.' Near the outer opening of the nostrils, numerous hairs grow, which serve to aid in straining the air of certain impurities. The sense of smell is situated in this delicate mucous mem- brane which lines the nostrils ; in it the filaments of the nerves of smell terminate. The greater proportion of the filaments, for their better protection, end in the upper part of the membrane ; and here the sense of smell is most acute. Consequently, when you wish to perceive a faint odor, or to smell something more dis- tinctly, you snuff up the air, or sniif. There are no papillae con- nected with the sense of smell. This sense acquaints you with the nature of odorous particles in the air, and thus aids you in judging as to its purity ; it also aids in the selection of food. It may be much modified and injured by habit, and you may improve it much by cultivation. You should therefore endeavor to preserve the delicate lining of the nostrils in a clean and healthy state, and not expose it habitually to irritating or foul odors. A most perfect natural respirator is formed by the nostrils. The walls tend to warm and moisten the air, while the irregular passages and the hairs, as well as the somewhat tenacious moisture, strain and greatly aid in purifying the air; especially retaining many of its solid particles, as proved by the dust and other foreign sub- stances often collected in the nostrils. Endeavour, therefore, to form the habit of breathing through the nostrils only, by keeping the lips closed. SENSE OF HEARING. — THE EAR. — SOUND. The ear is made up of a number of distinct parts, but it is usually described as having three divisions : — the outer (external)^ the middle, and the inner ear. The outer ear consists of the visible part, the pinna, commonly known as the ear, and the auditory canal. This canal leads mto the head, about an 44 ELEMENTARY ANATOMY AND PHYSIOLOGY. inch, where it is closed by the drum or middle ear. The pinna is composed of cartilage covered with skin, and collects and brings together sounds, which are then conveyed by the canal to the drum. Numerous hairs, as you can see, grow upon the skin that lines the canal, which with a waxy substance given out by glands in the skin, tend to prevent the entrance of insects (Fig. 26). Fig. 26. Fig. 27. Semicircular canals and cochlea^ magnified. (( Fig. 26.— The Ear— A, pinna; B, audi- tory canal ; C, tympanic membrane ot drum ; P, drum'or middle ear ; E, eus- tachian tube leading from throat ; F, F, F, semicircular canals ; G, Cochlea. The middle ear, or drum, is an irregular cavity, lined with mucous membrane, situated at the inner end of the auditory canal, in the bony floor of the skull. It contains three little bones, which stretch across the cavity, from the outer to the inner ear ; and which have moveable joints, and give attachment to four little muscles. That part of the lining of the drum which covers and closes the inner end of the auditory canal is called the tympanic membrane. Sometimes this is lax, and at other times it is stretched and made tense by the action of one of the little muscles above mentioned ; thus modulating or regulating the intensity of the sounds striking it. A small open canal, the eus- tachian tube, leads from the middle ear to the throat, and thus admits air into the drum. The inner ear, or labyrinth, has three distinct parts : — a com- mon central cavity or vestibule, three semicircular canals, and the cochlea. The canals are three bony passages, each forming more than half a circle, and opening by both ends into the vestibule. The cochlea is a winding or spiral tube or canal, and much resembles a common snail-shell (Fig. 27). The canal is The pinna md brings nal to the : skin that by glands ^ 26). and cochlea. )inna; B, audi- membrane ol le ear ; E, eus- )m throat ; F, s ; G, Cochlea. lined with i auditory ttle bones, inner ear ; nt to four ich covers :alled the ther times r the little ating the the eus- , and thus : — a com- nals, and h forming into the :anal, and canal is SENSE OF HEARING. 45 divided from end to end by a thin partition into two smaller canals. At the large end, one of these opens into the vestibule and the other into the drum ; while at the small end, the two communicate with each other, where, it is supposed, waves of sound meet and destroy each other. Within this bony labyrinth, and considerably smaller than it, is a membranous labyrinth, a sort of irregular sac. This is surrounded, and also nearly filled, with a fluid, and contains, besides, floating in the fluid, two very small stone-like bodies, the otoliths. Upon the wall of this sac, minute filaments of the nerve of hearing (auditory nerve) are so arranged that they are touched or knocked by the little otoliths when these are set in motion, as they always are, by the waves of sound which enter the ear. The sac and the otoliths are the essential parts of the organ of hearing. In some little animals, the entire ear consists simply of a small sac, filled with a fluid and an otolith, with the nerve of hearing spread upon the sac. But these little animals, though they can hear, cannot, as you can, with your much more complicated structure, comprehend the beauties nor the qualities of sound. While one part of the nerve of hearing is distributed on the little membranous sac in your inner ear, the other part of it is distributed on the partition which divides the canal of the cochlea into two tubes. Here, the filaments are of different lengths, being shorter and shorter as they are nearer the inner end or apex of the cochlea, where both the canal and the partition are much narrower than at the base. In this respect the filaments resemble the strings of a piano or harp. The three divisions of the ear, then, are quite distinct from each other. The outer division is exposed to the outer air; the middle one is filled with air, which enters readily through the tube lead- ing to it from the throat ; and the inner division, in which are the most essential parts, contains a fluid. The nature of sound must be understood in order to under- stand the functions of the ear. All bodies which give rise to sound are in a state of vibration — moving rapidly to an'' ^ro, and they communicate like vibrations to any medium or linng with which they are in contact. You have no doubt seen a stretched cord or a violin string vibrate. You have, too, most likely, dropt a stone into water and observed that the water is thrown into circular waves. Now a vibrating body throws the air into similar waves, but there is this difference ; while the water waves pass along a single plane, as on the surface of the water only, waves of sound pass in every imaginable plane — in every direction. I' !l 46 EI.rMENTARY ANATOMY AND PHYSIOU)GY. The sensation of sound is produced by these waves. If you strike the table with your fist, the blow sets the tabic vibrat- ing ; the church bell is set vibratini^ by the stroke of its tongue or clapper; the vibrations of the table and bell cause like vibrations, or waves, in the air, which rapidly reach the drum of your ear, and hence, are communicated to the nerve fibres of the inner ear. The functions of all the different parts of the ear are not fully understood, but the organ deals with the di '•'^y quantity or intensity y and quality of sounds. The direc tiom which sounds come are believed by some to be determined simply by the relative intensity of the sound on the two ears ; others believe it to be determined by the semicircular canals. Intensity of sound is measured and regulated by the tympanic membrane, the tension of which is varied, as stated above, by a little muscle. The waves of sound, collected into a sort of focus by the pinna, flow with accumulated intensity through the auditory canal, and striking the tympanic membrane of the drum, are communicated, probably both by the chain of little bones and the air in the drum, to the fluid in the inner ear. The otoliths in the mem- branous sac are now set vibrating, and they knock against the nerve filaments in the memi)rane, and the filaments convey a sensation of sound to the brain. The quality of '■• id or tone is seemingly determined by the cochlea. SENSE OF SEEING. — THE EYE. LIGHT. The eye, whicti gives to the countenance its most important element of beauty, is a nearly globular body, moving freely, in a sort of fatty cushion, in a cavity (the orbital) in the front aspect of the skull. You should get from a butcher an eye ball, carefully removed from the head of a sheep or, better, an ox, with, if pos- sible, a portion of the nerve trunk attached, behind. The eye in all the higher animals is almost exactly like the human eye. You will find on the outside of the ball, if they have not been cut away, some fleshy fibres — little muscles, which served to move or roll the ball in the socket. Beneath the muscles is a thick, strong, white, fibrous layer, or membrane (the sclerotic), which main- tains the globular form of the eye-ball and gives attachment to the muscles. In some respects it resembles an india-rubber toy ball. The front fifth of this layer is perfectly transparent, being quite different in structure, and is called the cornea. Immediately within the other four-fifths is a dark lining membrane (the choroid); aves. If Ic vibrat- ts tongue 'ibrations, your ear, inner ear. ar are not quantity otn which simply by rs believe tensity of jrane, the e muscle. he pinna, :anal, and lunicated, air in the the mem- gainst the convey a or tone is important "reely, in a t aspect of 1, carefully th, if pos- i eye in all ?ye. You been cut move or is a thick, bich niain- ent to the r toy ball, jing quite mediately 3 choroid)] SENSE OF SEEING. 47 and immediately within this again, is a third membrane, of great delicacy ('the retina). This last consists chiefly of filaments of the optic fierre, which enters behind and at once spreads into this membrane. So you will find, if you dissect the eye-ball care- fully, first, a thick strong membrane; next, a thinnish dark one; and lining them, a third, a very delicate nervous one. The contents of the eye-ball, — or of the chamber walled in by these membranes, are mostly perfectly transparent fluids. If you cut the eye-ball, from before backward, with a sharp knife, into two lateral halves, you will find its cut surface closely re- semble Fig. 28. Near the Iront of the chamber, a little behind the cornea, is the lens. A lens is a transparent substance, so formed as to change the direction of rays of light passing through it. The glasses in spectacles are lenses. In your eye the lens is doubly convex — swells out on both sides, and is soft and highly elastic. It is held in its place by a membranous frame, and connected with its border are muscular fibres which draw on it and lessen its convexity — make it thinner, at times, and so adapt it to the different distances at which objects are when you look at them. The lens, observe, divides the chamber of the eye into two smaller chambers ; quite a ^^inall one in front, which is filled with a thin fluid, and a much larger one behind, filled with a thick fluid, like soft jelly. The iris is the most interesting part of the eye. It is a sort of circular curtain, hanging in the thin fluid in front of the lens. It is so named (iris, from a Greek word signifying rainbow) on ac- couni of its various colours ; it has different colors and shades in difi rent individuals. If one's iris is blue, one is said to have blue eyes. In the centre of the iris is a round opening, the pupil, which always appears black, because you see through it into the dark chamber of the eye. The iris consists chiefly of delicate muscular fibres, some circular, some radiating, so arranged as to lessen or increase the size of the pupil, and thus regulate the quantity of light entering the eye. In a strong light the pupil. be- comes smaller, in a feeble light it gets larger. If you bring a lighted lamp near to the eyes of another person you will find the pupils of his eyes become gradually smaller, and larger as you withdraw the light. Light is believed to consist of the undulations or waves of an exceedingly thin, elastic substance, diffused throughout all space. It is supposed that the waves of this substance give rise to the sen-/ sation of light to the eye, as the waves of air give rise to the sen- 48 ELEMENTARY ANATOMY AND PHYSIOLOGY. sation of sound to the ear. Luminous bodies, as the sun or the flame of a lamp, produce the waves, it seems, and so give rise to, or give off light, and in every direction. A ray of light is a single line or wave of light proceeding from a luminous body. When a ray meets in its course with any substance, the ray either passes throui^h the substance, or is taken in or ab- sorbed by it, or turned back or reflected by it. You know what a reflector is ; a piece of bright metal placed behind the flame of a lamp for reflecting, or turning back, the rays of light falling upon it from the lamp, and diffusing them through the room. A lamp shade reflects or turns the rays down on your book so that you can see the print better. Rays of light pass through transparent bodies, as glass, water, air. Black substances take in the rays. You know if you place your hand on anything black lying in the sun it feels hot ; this is because it has absorbed the sun's rays. Most substances reflect more or less of the rays which fall upon them, but light colored substances reflect the most. Fig. 28. Fig. 29. E.ve-ball, in section, showing the three layers of membranes forming its walls, and the cornea swel- ling out a little in front, with a portion of the optic nerve behind. A, lens ; B, large chamber, behind ; C, the pupil. Above and below C, faint outline of iris, cut throTigh the middle. Eye-ball in its socket in the skull, showing muscles, and blood-vessels entering behind. Objects are seen by means of the rays of light which are re- flected from them. The reflected rays enter the eye through the pupil, pass through the lens and fluids, and are absorbed by the dark membrane lining the chamber, producing a sort of heat pic- ture. This picture is ' felt ' by the filaments of the nerve spread out here in infinite numbers, and the nature of it, — of the im- pression produced, is by them conveyed to the brain. I have told you that a lens is for the purpose of changing the course or direction of rays of light. Fluids do the same thing. And the in or the '^e rise to, f light is luminous tance, the in or ah- )w what a lame of a ig upon it A lamp at you can ansparent the rays, ing in the un's rays. fall upon SENSE OF SEEING. 49 Dcket in the luscles, and ng behind. lich are re* lirough the ed by the f heat pic- rve spread -of the im- . I have course or And the use of the lens and fluids of your eye is to slightly turn the rays of light which are reflected from the object at which you look, and bring them to a focuSy or nearer together ; so that they will im- press the heat picture of the object in the most favorable position and manner upon the dark membrane and nerve filaments. There are a number of appendages to the eye ; some motive^ for moving it, others protective. Attached to the outside of the ball, are six muscles (Fig. 29), which move or roll the ball in all directions, and which have been referred to. With these muscles you can turn your eyes at will toward any point. The eye-lids contain plates of cartilage, and afford great protection to the eye. Connected with the upper lid, and serving to raise it, is a little muscle. The eye lashes, when touched by any object, cause the lids to close suddenly over the eye. A very delicate transparent mucous membrane, the conjunctiva, is spread over the front of the eye ball, and also lines the inner surface of the lids. Near and above the outer corner of the lids of each eye is a small body, the lachrymal gland, which produces a fluid, the tears, for moistening or lubricating the outer Fig. 30. surface of the conjunctiva, and preventing friction during the movements of the ball and lids. Near the inner corner of the lids is the upper opening of a little tube, the nasal duct^ which leads into the nostril and ordi- narily conducts the fluid of the eye into this cavity (Fig. 30). Dust and other particles are often washed from the surface of the eyes through these ducts into the nostrils. The eye-brows, besides adding to the rnFtho"na8ri''ductrB. beauty of the face, prevent the ' sweat of the brow ' flowing into the eyes. Front view of the eye with the lids 80 removed as to show the lachrymal ^'lanU.A; CHAPTER VII. THE BLOOD AND ITS CIRCULATION. We now come to the study of the organs and functions most directly concerned in the nutrition of the body, — in sustaining life^ —the vegetative organs and functions. You have been told, you will remember (pages 12, 17), that your body is continually wearing away, just as a machine wears from use ; that you cannot think or move without the destruction of some particles of your- so ELEMENTARY ANATOMY AND PHYSIOLOGY. II self; and that nutrient matter — food, is required for renewing the worn parts. Food is also required for the formation or growth of| the tissues. You also require heat to keep you warm, and there- fore fuel must be provided for burning ; and a part of the food! you eat is burned, that is, oxidised, in your body, as fuel, and pro- duces heat. And furthermore, you cannot think or move without force, or it might be called strength. The locomotive steam engine ; however perfect and complete in all its parts, cannot move or be moved without a something not exactly a part of the engine, and this something is called force — the force which steara supplies. To produce the steam there must be heat, and fuel- wood or coal — is burned. So, though yo ' ave your bones and joints, muscles and nerves, all in perfect jndition, you cannot move without something more, and this something is force. It ap- pears that the heat generated in your body, gives rise to, oil becomes force. If the supply of the nutrient blood is cut offi iVom your arm, the arm soon becomes cold, and you are unable,] from want of strength, to exercise its muscles and bend the limb. The most prominent functions of nutrition are digestion andl circulation. Digestion is concerned in dissolving and preparing nutriment — tissue matter and fuel for burning ; and in the blood these are carried about, or circulated, to every part of the body, We will first study the blood and how it is circulated. A circulating nutritive fluid, which in plants is called sap and in animals blood, is found in all living objects. Every plant, from the smallest flowf^r that adorns the garden, to the lofty oak, — roots, stem or trunk, and branches — is full of sap. Perhaps you have seen it flow from the sugar-maple, in the early spring- time, as it does in pail-fulls, after the tree has been * tapped ' by| the wood-man ; who obtains from it large quantities of maple sugar. Or you have seen the milky sap ooze from the dandelion! stalk after you have broken or cut it in two. You know ifl you cut yourself with a knife or prick yourself with a needle through the cuticle into the true skin, anywhere on your body, (the cuticle, as you have been told, remember, contains no blood) the red blood comes out, and, too, through the smallest wound you can make. In all the highei ."nimals the blood is red, like your own, but in fishes and the lower animals it is white. In all,[ it is continually moving, as also is the sap in plants, moving, orj circulating. Blood is a very complex fluid, and a very wonderful fluid! It is considerably thicker than water, and contains, in solution— THE BLOOD AND ITS CIRCULATION. 51 lewing the growth of and there- f the food 1, and pro- ve without ive steam ts, cannot part of the hich steam and fuel- bones and 'ou cannot ce. It ap- rise to, or is cut off are unable, d the limb, ^estion and i preparing the blood Df the body. s called sap wery plant, e lofty oak. Perhaps :arly spring- tapped ' by s of maple- s dandelion )u know if :h a needle your body, IS no blood) .llest wound is red, like lite. In all, moving, or iderful fluid. \ solution- dissolved in it, a vast number of substances, — more or less, indeed, of every element and compound of which the body is composed ; and it also contains many waste compounds, which, however, are usually quickly removed by certain organs, the scav- engers of the body. Besides all these, blood contains — i.ot dis- solved, but suspended or floating in it — and carries about with it, an immense number of minute cells, which we may look upon almost as little organisms (see page 10). They are not like any other cells in the body, and are called corpuscles. The blood corpuscles give to blood its red color : all the redness in blood is in the corpuscles. Remove these, and the remainder is almost colorless. If you examine a drop of your own blood with a microscope of high power — and if you never have so examined a drop of blood, you sh uld endeavor to get an early opportunity to do so — you will see many of these little bodies in it. Most of them are circulai, with flattened sides, some- what like a piece ot coin, and thicker about the border than at the centre — dimpled. They sometimes form in clusters, which look. like piles of coins (Fig. 31). They Fig. 31. are so thin that placed thus, ten thous- and of them would only extend the length of an inch. Put edge to edge, on a flat surface, about three thousand would extend across an inch. When you see one by itself, it appears of a yellowish color, but a number of them together are distinctly red. They are soft and delicate, and very easily broken in pieces, and may be compared to minute discs of red jelly ; yet they bear a great degree of pressure. They con- Blood corpuscles, Wghiy magnified, tain iron combined with oxygen. And they are made use of constant- ly in the nutritive processes; while they are as constantly reprodu- ced. You can form an idea of the vast numbers of these corpuscles in the blood, when I tell you it has been estimated that twenty mil- lions of them are used or destroyed during each pulsation of the heart. If you look attentively, you may see, besides the red cor- puscles, a few others, which are larger, colorless, and round, like little balls. These are called white corpuscles. They have a strange power of changing their form, and assuming odd, irregular shapes, even while you look at them. Blood then consists of a fluid containing a great many sub- stances dissolved in it, with countless millions of cells floating in< 52 ELEMENTARY ANATOMY AND PHYSIOLOGY. it, most of which are red, and which give to the blood its red color. Blood becomes solid, or clots, soon after it leaves the living body. Possibly you have seen a person * bled ' by a phy- sician, or a horse bled in the neck, or an animal butchered, and observed, first, how freely the fluid blood flowed from the cut of the lance or of the butcher's knife ; and, secondly, that this blood soon became so solid that you could take it up in lumps, — that it had coagulated or clotted. Whenever blood is drawn from the living body, some change very soon takes place in it, or some- thing is formed in it which was not in it before, and il solidifies in this way. But it does not become solid because it has become still, nor because it is exposed to the air, nor because it gets cool. If it is kept warm it clots just the same ; and if kept cold enough it will not clot at all. If you wish lo learn all you can about blood, you should ob- tain two bowls filled with it, fresh, say from a butcher ; that from any of the domestic animals can hardly be distinguished from human blood. Set one bowlful aside, and take a little bundle of twigs and stir that in the other bowl rather quickly for a little time. But, remember, you should commence to stir it the minute it flows from the living body. When you withdraw the twigs you will find adhering to them a soft, stringy, reddish mass ; and if you wash this in a stream of clean water you will thus remove the red color — consisting of red corpuscles — and you will have a white net-work of soft, delicate, elastic threads L.f nearly pure fibrine. If you wash a clot of blood in a like way you obtain a net-work of the same (see page lo). Some believe that fibrine exists in the blood while it circulates in the body, and that this solidifying into threads is, as it were, its last living act ; others believe it is formed only, though immediately, after the blood leaves the body. How- ever this may be, by stirring the blood with the twigs, you removed most of the fibrine ; and for this reason, observe, the blood in this bowl will not clot. If you now examine the blood in the other bowl, say in half an hour or an hour after it has been taken from the body, you perceive it is no longer a fluid, but a soft solid, and if you were to turn it out of the bowl it would keep its form, that of the inside of the bowl, like a shape of jelly. But you should let it stand till the next day, and then examine it, and you will find, not a large clot filling the bowl, as you might ex- pect, and as you find on the first examination, but a clot con- siderably smaller and harder, floating in a clear, straw-colored fluid. This fluid is called serum. h its red iaves the by a phy- ered, and he cut of :his blood ips, — that from the or some- Dlidifies in i become gets cool. Id enough hould ob- ;her ; that ished from bundle of little time, ite it flows you will nd if you >ve the red Lve a white ire fibrine. let-work of ists in the lifying into t is formed dy. How- »u removed e blood in )od in the been taken but a soft Id keep its jelly. But line it, and might ex- a clot con- aw-colored THE BLOOD AND ITS CIRCULATION. 53 The clot is formed in this way : almost immediately after (blood is drawn from a living body, the fibrine commences to form into a multitude of very fine threads, which become a close net-wcrk, and the other constituents of the blood are held or shut up in an immense number of minute chambers or meshes, formed by the threads of fibrine, somewhat like water is held in a sponge. The threads of fibrme, as soon as formed, begin to shrink, and the fluid in the little chambers is squeezed by the shrinking of the thread walls of the chambers, and the thin parts of the blood —the serum with the dissolved substances in it, escape, but the floating corpuscles are caught and retained in the meshes. This shrinking and squeezing goes on until the clot consists of little dse than the corpuscles entangled in a net-work of fibrine, and which floats in the forced-out serum. The serum contains all the other substances which exist in blood. It holds in solution a large quantity of albumen (7 or 8 parts in 100). White of egg is nearly pure albumen. In twelve ounces (about a tea-cupful and a half) of serum, there would be nearly an ounce of albumen, about equal to the white of one egg. You know if an egg is placed for a little time in boiling water, the white soon becomes hard, so hard that you can cut it in thin slices with a knife. Heat causes albumen to become solid. So if you were to try to boil some serum, before it would boil, it would be- come almost if not quite solid, because of the albumen in it. The albumen is the great representative of the nutritive substances, and is obtained from the albuminous foods eaten. You have now learned that the blood contains red and white corpuscles ; that it contains fibrin, — if not as such when in the body, something so like it that it becomes fibrin almost as soon as the blood escapes from the body ; and that it contains a large amount of albumen. Besides these substances serum contains fatty matter and many mineral salts, such as are found as constituents of the body (see page 13.) The fats are derived from fatty and oily foods, and are chiefly employed as fuel in the generation of heat within in the body ; though a portion is used by the nervous tissue. Any surplus is stowed away with cellular tissue in certain spaces, as a reserve supply, and constitutes the fatty tissue. The mineral salts, too, can only be obtained from the foods. Hence, the importance of a properly selected diet ; containing all the essen- tial constituents for the growth and renewal of the body. The blood flows in canals, or vessels, in your body, and does not ooze about hither and thither among the fibres of 54 ELEMENTARY ANATOMY AND PHYSIOLOGY. the tissues, in simple passages. It is contained in special walled vessels, and moves in one constant direction, and in continued streams. In the sabstance of the tissues many of these vessels are far finer than any of the hairs on your head, and have the thinnest and most delicate walls. These are called capillaries (from capillus, a hair). Each of the little papillse in your skin contains a number of these little vessels ; each of the little, soft, muscular fibres of which your flesh is made up is wrapped round with a net work of capillaries. And not only in your skin and flesh, but in your brain and in almost all other parts and organs of your body, so thickly set are these little vessels that you cannot thrust in even the finest needle without piercing one or more of them, when out will flow the crimson drop. If you have never looked through a good microscope at a thin^ transparent, living animal membrane — as the wing of a bat, or the web of a frog's foot — and '"itched the blood coursing in its nar- row channels, you should not fail to do so on the first possible opportunity. It is a very in- Fig. 32. teresting and instructive sight. Figure 32 will give you an idea of its appearance until you can get an opportunity to see it in the living tissue ; where you would see the corpuscles mov- ing along, as if chasing each other, in the little vessels, in a fluid — the serum — so clear that you could not see it. Now, in almost every part of your body, hear in minH «5r»niPt-liincr v^^rir CapiHary circulation of a frogs foot, highlj Dear m mma, SOmetnmg very magnifled. Tlie corpuscles are shewn, resemb- similar would be seen if the l«ng chains, in the minute vessels, moving u ^- ^^„„^^„ ij u I u^ ^ the direction indicated by the arrows. The microscope could be brought to Wack spots between the vessels arc pigment bear upon it. Larger vessels •-'®^'^' ^'^'*^*^ ^'^® '° *^® ^^^ '*^ ^'^'^'^ '^°^°'' as you will learn presently, convey the blood from the heart to the capillaries in the tissues ; and larger ones, too, convey it back to the heart again. The blood is like a great circulating market in the body. It supplies to all the various tissues nutriment for their growth and repair, fuel for burning, and materials to the stomach, liver, and other organs, for the exercise of their functions. From it, all that is wanted by the various parts— by the skin, the brain, the bones, the flesh, is obtained ; while, on the other hand, it ;ial walled continued vessels are le thinnest ries (from contains a , muscular with a net esh, but in your body, ust in even when out e at a thin, bat, or the in its nar- it possible THE BLOOD AND ITS CIRCULATION. 55 ■og's foot, highly 3 shewn, resemb- ssels, moving in he arrows. The els arc pigment ts black color. he heart to nvey it back ket in the int for their the stomach, ions. From ti, the brain, her hand, it takes, as it were in exchange, and carries away, the refuse, the used, worn-out matters of the parts. We might compare your body to a great city, having a complete net-work of canals, con- taining flowing water, in its streets, for conveying to the houses, say in little boats, the various commodities and merchandise required by the inhabitants, and for carrying away, at the same time, the waste or refuse matters of the households. What each household requires it obtains from the boats on the canals, giving them at the same time the refuse of the house. What your muscles want, they obtain from the blood ; what your brain wants, it obtains f^rom the blood ; and so with every other part of your body. What they have used and do not require any longer, they give back to the blood — to be soon though, remember, taken, for the most part, from the blood, by certain scavengers — glands of the skin, kidneys — and cast off from the body. Your muscles cannot act without blood circulating in them ; nor indeed can any of your organs If you were to tie a thread round the little vessel which carries the supply of blood to your biceps muscle, in a little time you would not be able to shorten the muscle or bend your arm. There would not be any strength or force in the muscle ; and it would become colder than usual. So you see that although a muscle cannot act without un- broken nervous connection with a nerve centre (see page 37), something more than this is necessary. Nerves influence and control muscles, but do not give anything to them ; but blood supplies something — oxygen and other elemeiits, heat and strength —without which muscles cannot act. Nerve matter cannot act without blood. If anything were to prevent the blood flowing to your brain you would instantly become insensible. No organ can perform its function without a supply of blood — fresh blood, flowing constantly through it. But the blood flows in closed vessels ; how do the nourishing elements get from the blood to the little bits of tissues, and the waste elements get into the blood, through the walls of the vessels? The property called osmosis, as you will learn, plays a most important part in the nutrition of the body. It is a property which all membrar es, such as a bladder, have of letting substances paso through them. If you take a very fine glass tube, open at both ends, and put one end of it in a drop of water, the water will rise in the tube ; and the smaller the tube, the higher the water will rise in it. All membranes have minute tubes or pores passing through them from one surface to the other, — however thick and 4 s* ELEMENTARY ANATOMY AND PHYSIOLOGY. firm, they are all more or less porous. You know that if you put your foot with your boot on into water, the leather, which is a thick membrane, allows the water to pass through its little pores and wet your sock and foot. If there are some substances, as washings or particles of the soil, or salt, in the water, the leather will allow these also to pass through it. The walls or coats of the capillaries are made of very thin membrane, and it is chiefly by this property, osmosis, that the nourishing materials in the blood get through their walls to the bits of flesh and other tissues between the capillaries. The serum of the blood passes through with ease, but the corpuscles are retained in the vessels. It is chiefly by osmosis, too, that the waste stuffs from the tissues ge: into the blood. Now about the blood-vessels. You have been told tha: besides the capillaries in the substance of the tissues, there are larger blood-vessels — two sets — one set to convey blood to the capillaries from the heart, and another set to convey \X.from the capillaries back to the heart, which is the great central blood-ves sel, and starting point of the circulation. These two sets oi vessels differ much from each other in structure: those which con- vey the blood from the heart to the capillaries have thick, stiff, though elastic walls, and, even when empty, are round like a piece of small rubber hose, and they are called arteries ; those which carry the blood back to the heart from the capillaries have thinner, flabby walls, and when empty their sides fall together, and they arc called veins. The blood-vessels then are, following the course of the blood, heart, arteries, capillaries and veins. The capillaries have been sufficiently noticed. Now you have two circulations, in reality, quite distinc: from each other, except that they are connected at one point — a: the great centre, the heart. You have two sets of arteries, two sets of capillaries, two sets of veins, and, in fact, two hearts, joined in one. One circulation is that in which the blood flow.s from the heart through arteries to all the capillaries in all the tissues of the body, through these capillaries, and back along veins to the heart again. This is called the greater or systemic circulation. The other is confined to the lungs, and is called the lesser or pulmonary circulation (fulmo, lung). In it the blood, just returned to the heart — loaded with waste matters from the tissues — flows again from the heart, through other arteries to the lungs, through other capillaries here — not to nour ish the lungs, observe, but to get rid of waste matters and obtain a load again oxyger throug tion loi just ho diagrai The all part circulal sisting ; ing a la blood i breast I the size called ■^ and an lungs, a ventricl auricle. but quit You pluck, the lo; and veil the two| all, the relation] you hav place respiratj parts or pluck is most, iind a s| with a closely faces of ments. pointing it, one organ, THE BLOOD AND ITS CIRCULATION. 57 if you put rhich is a ittle pores stances, as tie leather r coats of t is chiefly lis in the her tissues 2S through ;els. It is I tissues gei 1 told that I i, there are ood to the xifrom the blood-ves wo sets of I which con- thick, stiff, I like a piece hose which ave thinner.! ind they are the course e capillaries uite distinct le point — all arteries, two two hearts. blood flows 5 in all the back along greater or ne lungs, and sttlmo, lung). i with waste hrough other -not to nour s and obtain! a load of oxygen from the air in the lungs — and then along veins again back to the heart ; to be again sent with its lo.id of oxygen to all parts of the system. And so the blood flows first through one circulation and then through the other. In this connec- tion look over Fig. 36, but remember it is not a picture, representing just how the blood-vessels are really arranged in your body, but a diagram, to give you an idea of the course of the blood. The heart is a great forcing-pump, which drives blood to all parts of the body ; while it is also the great regulator of the circulation, equalizing the flow of blood. It is a fleshy organ, con- sisting almost entirely of fine, closely packed, muscular fihrcs, form- ing a large hollow muscle, which, by its act of contracting, forces the blood into the arteries. Your lieart is situated just behind your breast bone, a little toward the left, and is (on the average) about the size of your fist (Fig. 41). It has four chambers, two below, called ventricles, and two above, called auricles ; a ventricle and an auricle on each side. It lies slantingly between your lungs, and consequently the auricles are not directly above the ventricles. The heart of fishes has only one ventricle and one auricle. And you have really two hearts joined together into one, but quite separated by a thick partition (Figs. 33, 36). You should get a heart for dissection. Get a sheep's pluck, or a pig's pluck will do as well. And get one with the longest possible portions of the blood-vessels — arteries and veins — attached to the heart. The pluck consists of the heart, the two lungs, or lights, with the wind-pipe attached, and, below all, the liver; all closely resembling, both in structure and in their relations to each other, these organs in the human body. When you have done with the heart, put the lungs and liver in a cool place until you require them for examination when studying respiration and digestion. Cut away the liver now. Lay the other parts on a table with the wind-pipe — the large tube by which the pluck is usually hung up — pointing from you, and the heart upper- most, between the lungs. Entirely covering the heart, you will find a strong membraneous sac, the pericardium. This is lined with a thin serous membrane (page 16), another layer of which clcsely surrounds the heart, and the smooth, moist, opposing sur- faces of thetwo layers prevent friction during the heart's move- ments. Cut this sac away carefully, and with a sharp knife, pointing towards the centre of the heart, make two deep cuts into it, one on each side, extending from the largest part or base of the organ, down near to its point or apex, for you see it is somewhat 58 ELEMENTARY ANATOMY AND PHYSIOLOGY. Fig. 33. cone-shaped. You thus cut into the two ventricles, and you can see the great thickness of their walls (especially of those of the left one), and that they form the great bulk of the heart. Above them are the irregular, ear-shaped auricles, which have thin flabby walls. Examine the large vessels — arteries and veins — which ap- pear as if growing out of the upper part of the heart, and compare them with those represented in Figs. 33, 41. Cut open the auri- cles and you will find a large opening — a sort of trap-door, be- tween each of them and the ventricle of the same side ; but the partition between the two auricles and that between the two ven- tricles you will find entire, without openings. Now open wide the cut you made into the right ventricle (that toward your left) and you will find hanging down from the large opening between it and the auricle three pointed pieces of thin, whitish membrane, the tri- cuspid valve. In the left ventricle you will find two similar pieces of membrane, the bicuspid valve (Fig. 33). The flaps do not hang loosely, observe, but are all connected by means of delicate, tendonous threads with the wailsof the ventricles. These valves, while they permit the blood to flow freely from the auricles into the ventricles, as the ventricles fill, the blood gets behind the flaps, and they Diacrram of heart and the arteries , , • /,-.• v ^i iv^i and veins attao'..ed to it. A, A, auri- cloSe the Openmgs(Flg. 34); the little cies; v, v, veniricies ; B, B, aorta, giv- threads attached prevent them turn- ing branches to head, arms, etc. ; C, . . ^ . 0111 pulmonary artery, dividing into two mg Up mtO the auricles. bO blOOQ large branches, one to each hing ; D, ponnnt- flow hnrW into fVif nnrirlpc superior vena cava; E, inferior vena CannOC nOW OaCK miO ine aUHClCS cava ; F, F, pulmonary veins ; G, tri- from the VCntricleS. How doeS it get cuspid valve: H, bicuspid valve. .. r^i. ,. • 1 •% •.. outof the ventricles? as it moves on in its course. You will find near the openings just no^^iced, two others, one for each ventricle, leading into the two — the only two, large, round, stifl"-walled arteries attached to the heart. When the ventricles contract and their walls come close together, as they do at every beat of the heart, causing the beat, they force out all the blood that was in them into these arteries. But they at once dilate again, their walls separate, to receive more blood from the auricles. What prevents the blood, just Oiienil the aur| away, lunar v^ do.;D,: ventricll C, C, oj ventricl The branc you (Fig. artej of b^ tree, alle^ THE BLOOD AND ITS CIRCULATION. 59 you can of the Above n flabby ■hich ap- compare the auri- door, be- but the two ven- ^'ou made it toward i hanging ^between ted pieces ;, the tri- t ventricle pieces of alve(Fig. ig loosely, nected by )us threads lies. These le blood to es into the es fill, the s, and they [); the little them turn- So blood tie auricles does it get t moves on onced, two — the only the heart. 36 together, beat, they se arteries, to receive blood, just pumped into the arteries, flowing right back into the ventri- cles again, as they dilate ? Slit up both arteries, and just where their yellow, firm walls join the soft fleshy heart, you will find, in each, a row of three most beautiful, sort of watch-pocket, semi- lunar valves, surrounding the opening. The instant the ven- tricles start to dilate, after pumping the blood into the arteries, with a click, these valves fly back and close the openings (Fig. 34), and so the backward flow of blood is prevented. Now about the arteries, which carry the blood from the heart to the capillaries. The two large ones which we have just now noticed, leading from the ventricles, are the two great arterial trunks of the two circulations, — trunks of two great arterial trees. Fig:. 34. Fi^'. 35. Openings or orifices of heart, from above ; the auricles, arteries and veins being cut awaj. B, opening into aorta, with semi- lunar valves, closed ; A, pulmonary artery, do.;D, D, opening between left auricle and ventricle, with bicuspid valves, closed ; C, C, C, opening between right auricle and ventricle, with tricuspid valves, closed. The carotid artery in the neck, dividing near the jaw into two branches ; one pa.ss- ing inwardly to the brain, the other sup- plying the scalp and other tissues covering the bruin. The one from the left ventricle is called the aorta, and sends branches to all parts of the body ; and it was necessary to cut it you see before the pluck could be separated from the carcase (Fig. 33). The other, from the right ventricle, the pulmonary artery, sends branches to all parts of the lungs. The branches of both divide again and again, and the branches, like those of a tree, become smaller as they become more numerous, until they all end finally in the minutest twigs (Figs. 35, 41), which always 6o ELEMENTARY ANATOMY AND PHYSIOLOGY. end and empty in capillaries. If you cut an artery across, the blood gushes out principally from the end nearest the heart ; which proves that the blood moves from the heart toward the ca- pillaries. And if you wish to stop the bleeding you must tie the artery between the cut and the heart. When a vein is cut across the blood flows most from the end nearest the capillaries. Often smaller branches of arteries, and likewise of veins, in the systemic circulation, unite (anastomose) with other branches, so that when a branch vessel supplying any part is injured, or cut or tied by a surgeon, the part receives a partial supply of blood indirectly through other branch vessels. The aorta in man is about an inch in diameter, and after ascending a little, curves backward and then downward, forming the arch, which gives off large branches to supply the head and arms (Fig. 33). The aorta then extends down through the chest and abdomen, resting against the spine, and gives off small branches to the walls of these cavities, and larger ones to the organs in the cavities — heart, lungs, liver, stomach, intestines. It then divides into two vessels, one of which passes down each of the lower limbs, giving off branches in its course down to the foot. If you press the balls of your fingers firmly on your groin — just where the front of the thigh seems to join the belly — you will feel the throb of this large artery. It now dips deeply into the flesh and passes down the inner side of the thigh, as the femoral artery, to the flat space behind the knee, where you can feel it throb. The artery supplying the arm you can feel in the arm- pit ; again at the inner side of the biceps tendon at the elbow ; and lastly, the chief division, at the front of the wrist, near the outside, where it is usual to feel the pulse. You can feel the throb of the two large carotid arteries in your neck, and that of the temporal, just in front of your ear. The pulmonary artery soon divides into two branches, one for each lung (Fig. 33). The veins commence, like the arteries end, by minute branch- es, or rootlets^ at the capillaries ; from which they collect the blood — which has just flowed through the rafiil ' from the arteries — and carry it back to the heart V He tlie arteries di- vide and subdivide, as in Figs. 35, 41, »ib follow t' •? opposite course ; the little rootlets unite with a other and rm larger vessels, which again and again unite in*. * still ^ rger, until at last all those of the systemic circulation have jc ned into two great venous trunks. All from the head, neck, and arms join and forr" the superior vena cava ; and all from the trunk and legs fori.i THE HLOOD AND ITS CIRCULATION. 6i Lcross, the :he heart ; ird the ca- nst tie the cut across 2S. Often e systemic lat when a tied by a indirectly and after d, forming head and I the chest off small les to the intestines, own each ►wn to the your groin telly — you ly into the femoral Li can feel I the arm- le elbow; , near the . the throb hat of the rtery soon te branch- :ollect the from the .rteries di- ^ opposite rm larger til at last two great and forr" legs foriii the inferior vena cava. These both empty into the right au- ricle (Fig. 33 and heart). All the veins in each lung unite into two large pulmonary veins, and all empty into the left auricle. The walls of veins, unlike those of arteries, are soft and fall flat together when the vessels are empty. All the larger veins in the limbs, and many in the trunk, have in them a number of valves (Fig. 36), which close the vessels on any backward movement of the blood in them, and so prevent a backward flow. In their course the deep veins lie close beside the arteries. You will find a vein with the blood in it flowing toward the heart and an artery with the blood in it flowing/r^;;/ the heart, lying side by side (Fig. 41). The course of the veins just beneath the skin you can trace by the bluish tint they give to the skin over them. If on one of these on the back of your hand or arm you press your finger firmly, and move the finger back at the same time toward the hand, you will force the blood back, and the vein will swell up in front of your finger as you move it, but remain flat and empty behind it. If you look closely you may see a little knot here and there in the course of the vein you have pressed, caused by a bulging out at the valves, which partly close the passage but cannot fully resist the pressure of your finger. If you now remove your finger quickly, you will see a movement of the skin along the course of the vein you had emptied, caused by the blood as it rushes up toward the heart. Arterial blood and venous blood, as the blood in the arteries and veins, respectively, is called, differ from each other very much, both in appearance and composition. You would naturally expect this ; that blood in passing from the arteries to the veins through the systemic capillaries, and supplying the various tissues with new matter and carrying away the waste stuffs, would be much changed. In color, arterial blood is bright scarlet ; venous, dark purple. If you could obtain some blood from each of the vessels separately, you would be surprised at the diff"erence in color. The difference is caused by the blood giving up oxygen to the tissues, and taking in carbonic acid. Blood contains, besides the ingredients already mentioned, a large amount of gas, about half a pint to a pint of blood, chiefly oxygen and car- bonic acid. But the gas from arterial blood contains twice as much oxygen as that from venous blood, but not nearly so much carbonic acid. This is the principal diff"erence, though there are others. There is a third set of capillaries through which a part of 62 ELEMENTARY ANATOMY AND PHYSIOLOGY. the blood must flow in its every round, and which has not yet been referred to. This is in the liver. The capillaries of the stomach, intestines, and some other organs in the abdomen, unite into veins and form at last one large portal vein (Fig. 36), which Fig. 30. instead of joining the -ena cava, like other veins, passes to the liver. In the liver it divide? into smaller veins, which finally break up into another set of capillaries. These capillaries, together with the capillaries proper of the liver — into which the hepatic artery supplying the liver breaks up (Fig. 36) — unite togetherinto veins, which unite into larger and largei veins, and then empty into the vena cava. The course of the blood in your body is then as follows :-Start- ing from the left auricle (Fig. 36), the blood flov.s into the left ventri- cle, then into the aorta and on into the arteries, capillaries, and veins in the tissues of the body, and through the venoe cavse back into the right auricle. That part which leaves the aorta at the arch and goes to the head or arms, comes back to the heart by way of the superior vena cava ; that part which flows on down the aorta to the lower part of the body comes back by way of the in- ferior vena cava ; whatever part chances to turn off from the aorta in- to the branches leading to the stom- ach, intestines, and some other ab- dominal organs, must pass through Diagram of heart and other vc8sels, tWO SetS of Capillaries, One in the showing the course of the blood indicated tissucs of these organs, another in by the arrows; viewed from be 'una, s'> . *=•.'. that the sides wdl corresponcl «ith tlie the IlVCr, before gCttmg TitO tiie Bides of the observer. P, A, pulmonary _„„ _ _ TTrnm thp riaht n-iriVlp artery; P, V, pt)rtal vein ; H, A, hepatic ^^"* Cava. rrom me rigni aariClC artery; Ly. Ly, lymphatics; Lt, lacteals; the b^OOd flowS intO the right Ven- V, V, V, valves iu veins. . • i ^i • ^ ^v i ' ' ' tricle, then mto the pulmonary ar- tery anc through started, hearts, ( Blood 1 to the the less In \\ inches i slowly, not so f go the 1 space ol bably p; Wha at least of them or set 01 lacid in have a nerve ii they so in fact all that great foi the wall nected to do th ventricl All ries ana takes p measure whence opening open, bi arteries, round o: other en thi blotj walls of Elastic s t 5 not yet ies of the nen, unite 56), which I cava, like liver. In allerveins, to another :apillaries, ies proper the hepatic breaks up intoveins, ind largei :o the vena blood in >\ys :-Start- (Fig^ 36). left ventri- ,nd on into nd veins in id througli the right leaves the DCS to the ack to the erior vena ;^s on down Dart of the ^ of the in- tever part heaortain- the stom- e other ab- Lss through Dne in the another in 1 Jnto the ght auricle right ven- monary ar- THE BLOOD AND ITS CIRCULATION. 63 tery and on into the arteries, capillaries, and veins in the lungs, and through the pulmonary veins back to the l<;ft auricle, whence it started. Observe now, while you have two circulations and two hearts, each heart is not specially connected with either circulation. Blood flows from the left ventricle through the greater circulation to the right auricle ; and from the right ventricle through the lesser circulation to the left auricle. In the arteries the blood flies along rapidly, probably ten inches in a second of time. In the short capillaries it moves slowly. While back along the veins it moves faster again, but not so fast as in the arteries. It has been estimated that it will go the round of the circulations in about one minute ; and in this space of time, then, the whole of the blood in your body will pro- bably pass through each side of your heart. What makes the blood move or circulate ? There are at least four or five forces which aid in moving it ; but the chief of them is in the ventricles. The heart is a great hollow muscle, or set of muscles, with fibres passing in every direction, and inter- laced in a wonderful manner. Muscular fibres, you remember, have a property of shortening or contracting (page 36) — under nerve influence, and each time the fibres of the heart contract they so lessen the size of the chambers of the heart that there are in fact no chambers, so closely do their walls come together ; and all that was in them is forced out. The ventricles contract with great force, and both at the same instant, 'i'ou observed how thick the walls were, especially of the left ventricle ; which being con- nected with the greater circulation has a great deal harder work to do than has the right ventricle. The sudden contraction of the ventricl.s is called the beat of the heart. All the blood-vessels, bear in mind — heart, arteries, capilla- ries and veins — are always pretty well filled with blood. What takes place when the left ventricle contracts? where does its measure of blood go to ? It cannot get back into the auricle whence it just came, because the bicuspid valve has closed the opening. The semilunar valves at the opening into the aorta will open, but the aorta is already full of blood. The walls of the arteries, however, are elastic and will stretch. Tie a string tightly round one end of a piece of large artery, and pour water into the other end and you will find it will stretch considerably. So when th.^ blood in the left ventricle is pressed on by the thick, strong walls of the ventricle, the aorta will stretch enough to receive it. Elastic substances, as india-rubber, when stretched, try at once to 64 ELEMENTARY ANATOMY AND PHYSIOLOGY. get back lo their former size again. And the stretched aorta tries to regain its former size, and squeezes the blood in it, which, as it cannot now get back into the ventricle, because the semilunar valves are already closed, is forced on into the branches of the aorta ; these, in turn, send it to the smaller branches, and so it is forced on into the capillaries. And thus the over-full aorta and its branches relieve themselves by forcing blood on into the capil- laries; and the blood in the capillaries is pushed on into the veins. The veins were already full, but at the same time that the left ventricle pumped its blood into the aorta, the right ventricle emptied itself into the pulmonary artery, and almost instantly the right auricle emptied itself into the ventricle. So that almost before the blood is forced from the capillaries into the rootlets of the veins, the right auricle at the other end of the veins is ready to receive, and does receive — probably by some suction force — its measure of blood, and thus permits the blood to flow readily from the capillaries into the veins. And thus the blood is moved through the round of the greater circulation. Through the lesser, in- the lungs, it is moved in precisely the same way. Through the little bits of capillaries the movement of the blood is assisted by the chemical affinity or attraction (page 8) which exists between certain elements in the blood and others in the tissues. In the veins, muscular action — exercise, favors the movement of the blood. In acting, the muscles press on the veins, and the blood in them is forced toward the heart because it cannot flow backward by| reason of the valves in the veins. The regular action of your heart, as it beats, beats, beats,! and pumps out at every beat a measured quantity of blood, reguf lates and equalizes the flow of blood ; somewhat as the pendulum | of a clock regulates the movements of the wheels of the clock, Oftener than once every second your heart contracts and squeezes! out its contents. The auricles contract, both at the same time,[ then the ventricles contract, both at the same time ; then there isl a very brief pause, and this is all the rest the busy heart gets,[ The muscles of your limbs contract, for the most part, only whenl you will that they should, and then they rest. Your heart conf tracts without any influence from your will, indeed your will hail no direct control over it, and excepting the brief pause of a fracf tion of a second after every contraction, it gets no rest. Whetherj you are asleep or awake, lying down or running about, as long asl you live your heart works on incessantly, — its fibres shorteningj and lengthening, contracting and relaxing. THE BLOOD AND ITS CIRCULATION. 65 aorta tries which, as semilunar hes of the and so it I aorta and > the capil- ) the veins, lat the left t ventricle istantly the nost before tlets of the is ready to I force — its eadily from I is moved 1 the lesser, rhrough the assisted by 3ts between es. In the )f the blood od in them ickward by beats, beats, blood, regu- e pendulum f the clock, md squeezes same time, then there is heart gets, t, only when ir heart con- tour will has ise of a frac- est. Whether t, as long as! s shortening! What r..akes your heart contract ? Little sensory nerve fibres extend fror. a delicate membrane lining the chambers of your heavt to p,;rve-centres — ganglions (page 19), and little motor nerve fibres extend back from the centres to the muscular fibres of your heart. When blood is poured into the chambers a mes- sage is sent along the sensory nerve fibres to the centres, from which a motor influence is sent back along the motor fibres to the muscles of the heart, and they contract and force out the blood. And so every time the auricles get full of blood, round flies the nervous influence to their muscular walls, and they instantly con- tract, and pour the blood into the ventricles ; and every time the blood is thus poured into the ventricles, round flies another ner- vous influence to their thick muscular walls, and they instantly contract, and force the blood into the arteries, just as if they were resolved never to allow blood to remain in them a single instant. The pulse, or throb, felt when the finger is placed on an artery, s caused by the wave of blood moving along and stretching the rtery as it mov^s, and follows immediately every contraction of he ventricles. In a very young infant the heart and pulse beat 140 times per minute ; during childhood about 100 times ; while Iter the age of twenty years the average is 70 or 75 beats per inute. They beat more frequently when one is standing than ivhen lying ; and they are quickened by exercise and excitement. Thus vour restless heart pumps and pumps, and blood is forced all pa 'ts of your body ; and by the help of the elastic arteries, hemical attractions in the capillaries, muscular pressure on the eins, and some suction force by the auricles, it moves on in its ound — round after round. And as long as life lasts this continues nceasingly ; this wonderful, circulating, trading mart, supplying ew matter in exchange for old, flows restlessly on. When it eases to flow, life, too, at once ceases, in all parts of the body. CHAPTER VIII. RESPIRATION ; ANIMAL HEAT AND FORCE ; THE VOICE. Respiration is the function by which an interchange of gases |ikes place between the inner parts of a living body and the air water in which it lives. Animal bodies take in oxygen and give it carbonic acid gas ; vegetable bodies take in carbonic acid and 66 ELEMENTARY ANATOMY AND PHYSIOLOGY. give out oxygen. In the higher animals the special organs for this interchange of gases are the lungs ; in fishes, the gills ; in plants, the leaves. As, through your stomach the food you eat gets into your blood, so, through your lungs the gaseous food — oxygen- gets into your blood. But your lungs are something more than nutrient organs ; they are partly excretory organs, scavengers, for throwing off waste matter. A lung is nothing more than a broad, thin, delicate membrane, with one side exposed to the air, and the blood, in capillary vessels, spread out on the other. But the mem- brane is so folded as to form little sacs or cells, thus occupying as little space as possible, consistent with its function. So broad is this membrane, that it is said if it were spread out its surface would be thirty times that of the skin of the body. You know how readily liquids pass through membranes, by osmosis. Gases pass through them with equal readiness. Yoi remember that arterial blood is bright red, because it contain; twice as much oxygen and much less carbonic acid than venous blood, which is dark purple (page 6i). If you w'ere to fill a blad der with dark, venous blood and hang it up in the air, with the neck tied tightly, oxygen would pass in through the membrane and unite with the blood, and carbonic acid would pass out of the blood into the air, and in a little time the blood next the mem brane would be changed to the bright red ti.it of arterial blood. The lungs are made up, then, of two vast membranes (oni for each lung) folded into minute bladders, called air cells, witl little tubes, called bronchial tubes, leading from the wind-pipe for conveying air into the cells (Fig. 37). The air cells are irregu lar in shnpe, and each is covered with a close net-work of capilk ries ; so that the blood is on the outside of the cells and the airi within them. The cells cluster round the little tubes and thi branch tubes somewhat like grapes upon their stems. Imagine j^reat many clusters of grapes packed closely together, and tin stem of each cluster fastened to a larger stem, like the branche of a little bushy tree, and imagine all the stems and grapes hollow and each grape wrapped in a close net-work of hollow threads and you have in mind something, in structure, not very urn ike on of your lungs. The stems represent the bronchial tubts ; thi grapes, the air cells ; and the threads, the capillaries. Only some thing to represent the arteries and veins, for conveying the bloo to and fro between the capillaries and heart, would be wantins These in your lungs extend along beside the bronchial tubes. Yo have two lungs, one on each side, which with the heart and othe large ves the lungs water; h the air c see if yot of the pi The ^ tube, line taining ri sure and Below, i chial ti divide ai tubes, wh 37). At larger tul which CO The chiefly b; cular fibr tween e£ ribs are each by may see or those siderably spine, so raised b) lifted an( thus the creased, from the thin mus up deepl its fibres ward tht hand on chest is the depi The everythi Your ch ans for this in plants, at gets into -oxygen- more than vengers, for an a broad, air, and the It the meni' ccupying as So broad is its surface nbranes, by iness. You it contains :han venous fill a blad lir, with the : membrane ss out of the ct the mem- rial blood, [ibranes (oni r cells, ^yi le wind-pipe Is are irregu •k of capilla md the air i bes and thi Imagine; her, and tb :he branche rapes hollow low thread: ry umike on 1 tubes ; thi Only some ng the blooi be wantins [tubes. Yoi art and otht RESPIRATION. 67 large vessels quite fill your chest (Fig. 41). After air once enters the lungs, at birth, they always contain some air, and will float on water ; hence the vulgar name, * lights.' The membrane forming the air cells is elastic and will stretch considerably ; as you will see if you blow into the lungs of a small animal, or even into those of the pluck you have, by means of a quill tied in the wind-pipe. The wind-pipe, or trachea, is a stiff fi-. 37. tube, lined with mucous membrane, and con- taining rings of cartilage, which resist pres- sure and prevent closure of the air passage. Below, it divides into two large bron- chial tubes, one for each lung. These divide and divide into smaller and smaller tubes, which extend to all the air cells (Fig. 37). Above, the trachea swells out into a larger tube, or sort of box, called the larynx, which contains the vocal apparatus. The walls of the chest are formed chiefly by the ribs, with two layers of mus- cular fibres the intercostal muscles, be- ^^^ tubes oTone ^ tween each pair of ribs (rig. 38). Ihe leading to air cells, ribs are attached behind to the spine. Fig. 38. each by a movable joint, and, as you may see by examining your own ribs or those of another person, they are con- siderably lower in front than at the spine, so that when the front ends are raised by the muscles, the breast bone is lifted and moved forward (Fig. 38) ; and thus the breadth of the chest is much in- creased. The floorof the chest (dividing it from the abdomen) is formed by a broad, thin muscle, the diaphragm, which arches position ortheVibs "in inspiratio^^ up deeply into the chest, like an inverted dish (Figs. 40, 43). When its fibres contract — shorten, it becomes flattened, and presses for- ward the contents of the abdomen, as you can feel by placing )'our hand on your stomach when you draw in air, and the depth of the chest is thereby greatly increased. Thus both the breadth and the depth of the chest are increased by muscular action. The air, or atmosphere, has weight, and is always pressing on everything. It pours, a^ you know, into every crack or opening. Your chest is an air-tight chamber, and air cannot get between its Three ribs, showinj; the two lay- ers of intercostal muscles between. The dotted ines show the raised 68 ELEMENTARY ANATOMY AND PHYSIOLOGY. walls and your lungs. But air enters your lungs freely through the ever open nostrils, throat, and wind-pipe, and the lungs are kept so stretched as to always just fill the chamber. When you blow into a bladder it stretches, because the pressure of the air which you force in is greater than the pressure of the atmosphere outside the bladder. If, instead of blowing air into the bladder, you remove the pressure from the outside of it by means of an air pump, air will rush into the bladder and expand it. The walls of your chest keep or remove the air pressure from the outside of your lung? more perfectly than an air pump could, and so the lungs are always expanded by the air pressure on the inside of them. Some- times when an opening is made through the walls of the chest, and especially when one is made on each side, as by stabs, air enters in between the walls and the lung , and so compresses the lungs as to make brcaihing difficult or quite 'mpossible, and suffocation follows. Between the walls of the ch^.l and the lungs, on all sides, is a delicate serous membrane (page i6), having a double layer, which, like all such membranes, prevents friction during the movements of the parts on each other. It is called the pleura ; and an inflam- mation of it is pleurisy, of which disease you have likely heard. Breathing consists of two acts : I St, that of increasing the size of the chest and permittmg air to flow into the lungs ; and, 2nd, that of lessening the size of the chest and forcing the air out again. The size of the chest, remember, is increased in both breadth and depth : the front ends of the ribs are raised, chiefly by the outer layer of intercostal muscles, making the chest broader; and the diaphragm is flattened and drawn down by the contraction of its fibres, making the chest deeper; and air rushes through the wind-pipe into the lungs, keeping them pressed close to the wails of the chest. This is inspiration (Fig. 39). The outer intercostals and diaphragm now cease to contract, the ribs are drawn down, chiefly by the inner intercostals, and the diaphragm rises hi^h up into the chest again, helped up by the contents of the abdomen, which are pressed upon by the muscular walls of this cavity, and the stretched lungs return to their former size again. This is expiration (Fig. 40). We breathe thus from 16 to 20 times even minute; from 16 to 20 times every minute the ribs rise and the dia- phragm descends, and then both return to their former state again. \ .^hat causes the movements, so regular and so beautiful, of til i walls of your chest ? Not your will. You breathe without knowing it. You can breathe quicker or slower, take a long deep breath or a short one, but breathe you must. You cannot by any .: rough the re kept so blow into vhich you )utside the oil remove pump, air Is of your de of your ungs are m. Some chest, and ir enters in lungs as to on folio «s. sides, is a yer, which, novements 1 an inflam- y heard. ing the size ; and, 2nd, r out again. ireadth and y the outer ;r; and the itraction of hrough the to the walls intercostals awn down, ses high up : abdomen, cavity, and I. This is times even ind the dia- state again. beautiful, the without 1 long deep not by any RESPIRATION. 69 Fig. 39. Fig. 40. effort of the will prevent it. It is essentially an involuntary or reflex act (page 25). After each inspiration and expiration there is a pause of a second or more, and now carbonic acid accumulates and oxy- gen diminishes in the air cells, until the sensory nerve filaments, in the delicate membrane forming the cells, are affected, and they call for fresh air; a message in- stantly flies up nerve fibres to the medulla, at the base of your brain (page 2 1 ), the nerve centre of the breath- ing movements, and a motor influence (page 22) comes down other nerve fibres to the diaphragm and intercos- tal miicr>lf»c KirlrlinfT tViom WaUs of the chest dilated as ill inspiration, ami tai muscles, Oiaamg tnem contracted as in expiration. A. trachea ; B, breast act; they obey, your chest di- bone; C, cavity of the chest; D, iliaphraijm. lates, and air rushes in, — you breathe again. About 18 times every minute these messages fly up and down between your lungs and brain. If your medulla should get seriously injured, by disease or accident, the messages would no longer be sent down to the muscles of your chest, and you wjuld at once cease to breathe, and, very soon, to live. The quantity of air drawn into your lungs at each breath is small when compared with the quantity the lungs will hold. Your lungs are not filled to their greatest capacity, nor nearly emptied, at each breath. The lungs of a full sized man will hold, when stretched to their utmost, about 300 cubic inches of air. But after an ordinary inspiration they actually contain only about 200 cubic inches, or about two-thirds of what may be drawn into them by a forced inspiration. And only one-eighth of this, on an average — or 25 cubic inches, is pumped in and out at each respir- ation. After an ordinary expiration, therefore, his lungs will contain 175 cubic inches. The one-eighth o^ -e air contents of your lungs, which you pump in and out at every breath, is called tidal air, and that remaining after each ordinary expiration is called stationary air. There is then, observe, always a large amount of stationary air in your lungs. Now how does the tidal 70 ELEMENTARY ANATOMY AND PHYSIOLOGY. air get down deep into your lungs, and a free interchange of gases take place between the blood and outer air ? Gases diffuse and mix rapidly. If you fill a jar with one sort of gas and turn it mouth downward over a jar filled with another sort of gas, the gases immediately commence to mingle together, and in a short time both jars will be filled with the tho- roughly mixed gases. This mixing takes place rapidly and against gravity. It is constantly going on in your lungs. The tidal air you draw in at each inspiration quickly mingles with the stationary air already in your lungs, and the few cubic inches of air you almost immediately expel by expiration is not the same you had just drawn in by inspiration, but a mixture of tidal and stationary air. The blood in your lungs, as it moves along in the capillaries, is thus constantly bathed with air, which is partly renewed and purified at every breath. As often as once every minute, it ap- pears, all the blood in your body flows through the capillaries in your lungs, giving off all the while, to the air in your lungs, car- bonic acid, watery vapor, and other matters, which have greater affinity (pages 8, 9) for air than for blood, and taking in all the while, from the air in your lungs, oxygen, which has a greater affinity for blood than for air. You remember the principal difference between arterial blood and venous blood. Bright scarlet arterial blood, while passing through the systemic capilla- ries to the veins, gives up half its oxygen to the tissues and takes in a lot of waste matters, chiefly carbonic acid and watery vapor, and changes to dark purple venous blood. This flows to the heart, and is at once sent on to the lungs and into the pulmonary capillaries. Here it gets rid of the waste stuffs and obtains a load of oxygen, and becomes again bright scarlei in color. Expired or breathed air contains therefore a large excess of carbonic acid and watery vapor, besides some organic poison- ous matter, and much less oxygen than ordinary air. While ordinary air contains about 20 per cent, of oxygen and .035 per cent, of carbonic acid, expired air contains only 1 7 per cent, of oxygen, and fully 4 per cent, of carbonic acid. You consume pro- bably 12 or 13 cubic feet of oxygen every 24 hours, and throw off, by the lungs, in the same period of time, 16 cubic feet of carbonic acid — equal to 7^ ounces of solid carbon — and from 20 to 40 ounces of water, in the form of vapor. If you put a wineglassiui of Urae water in a half-pint bottle and blow your breath two or three times into the bottle, on shaking it, the lime water will be- come quite milky from the formation of insoluble carbonate ot e of gases ■ with one illed with to mingle 1 the tho- nd against lal air you tionary air ou almost just drawn air. capillaries, lewed and lute, it ap- pillaries in lungs, car- ave greater ; in all the > a greater ; principal i. Bright nic capilla- ; and takes ,tery vapor, ows to the pulmonary ;ains a load arge excess nic poison- dr. While 1 and .035 per cent. 01 msume pro- d throw off, of carbonic n 20 to 40 kvineglassfui eath two or Iter will be- larbonate ot ANIMAL HEAT AND FORCE. 7i lime (carbonic acid and lime, combined), which after a little time will settle at the bottom of the bottle. You know your every breath contains a great deal of moisture, as proved when you breathe on a cold mirror. You know, too, how the moisture from your breath collects and freezes about your mouth on your muffler in a cold winter morning. The carbonic acid and watery vapor are chiefly the products of combustion — burning, of the union of oxygen with carbon and hydrogen, by which your body is kept warm. In cold weather you breathe more air and oxygen, and give off more carbonic acid, than in warm weather : as you do likewise when taking exercise. The organic matter in expired air has a very disagreeable smell, and is very poisonous to re- breathe. ANIMAL HEAT AND FORCE. Heat is always produced whenever oxygen unites with any substance, as with the carbon and hydrogen of fats, — forming arbonic acid and water. It is the oxygen of the air uniting with the carbon and hydrogen of the oil in the lamp which produces the heat and flame. But things burn without giving light, when they burn very slowly. In the laboratory of the chemist, by the combinations taking place between the various chemicals used, heat is being constantly produced without light. You proba- bly know how the gardener warms the soil to force on his plants in the early spring. He puts under the soil a lot of refuse organic matter from the stable, which is in the act of decomposing — rotting. All organic substances in the act of rotting are simply undergoing natural chemical changes ; — the oxygen of the air is gradually uniting with the elements of the dead matter, which is therefore in reality burning, and heat is generated, and carbonic acid, watery vapor, and other substances are formed. Heat generated in this way the gardener utilizes to warm the soil for his plants. Now the union of oxygen with other elements, which is constantly going on in your body, gives rise to heat just as such union gives rise to it out of the body. The warmth of your body depends chiefly on the union, or combination, as it is called, >f oxygen with carbon, forming carbonic acid, and, in a less degree, of oxygen with hydrogen, forming water ; which products of burning are thrown out by your lungs. Most of the oxygen taken into your blood through your lungs, instead of remaining in the body and increasing its weight, unites with carbon and hydrogen, — elements which, for the most iJl 72 ELEMENTARY ANATOMY AND PHYilOLOGV. part, you take in as food, and is thrown off again through your lungs as a part of the carbonic acid and water; the remainder unites with other elements and gives rise to a certain amount of heat, and the compounds thus formed are removed from your body in various ways. The heat is distributed and equalized by the blood cur- rent. The chemical combinations which produce the heat take place in all parts of your body. But the quantity generated varies in different parts, and in certain parts it varies at different periods. The brain, the muscles, and the liver, are great generators of heat. The blood in the large vein in the neck, as it flows from the brain, is warmer than that in the large artery beside the vein, as it flows to the brain. The exercise of a muscle or set of muscles, as of the arm, bear in mind, increases the generation of heat therein, and the muscles exercised become warmer. And then the surface of your body is continuously losing heat, which passes into the clothes you wear or the bed you sleep in. So the temperature of your body would be very unequal in different parts and at different times if heat were not distributed by the circulation. The blood distributes heat therefore as well as fuel and nutriment ; and the blood-vessels may be compared to a vast system of hot-water pipes. The heat of your body is regulated, or kept within cer- tain limns, by the evaporation of moisture from the lungs, and from the skin, in the form of perspiration ; as, perhaps you know, a large amount of heat is required to convert water into vapor. When too much heat is generated in the body, or when one is in an atmosphere considerably warmer than the blood, the excess of heat, instead of making the body much warmer, is applied in the form of force or energy, which prepares the perspiration and forces it through the pores of the skin. You know that when any one is burning with fever (the heat of the body in fevers is greater than in health, by several degrees) the doctor tries to bring on free per- spiration, and as soon as the skin, instead of being dry and parched, beco mes moist or wet with perspiration, the patient gets cooler and feels more comfortable. The temperature of the deep parts of the body in health is usually about 100 degrees (F.), while that of the parts near the surface are 5 or 6 degrees lower. And while man has within him the power to maintain this temperature, if he eats and digests sufficient heat-producing food, though surrounded by an atmosphere 160 degrees lower or colder than his body — 60 degrees below zero ; he can, on the other hand, endure, by reason of the excess of heat being used in the evaporation of watery vapor, a temperature as high as 130 degrees or more. ugh your emainder amount rom your )lood cur- heat take ted varies t periods, rs of heat, the brain, as it flows , as of the erein, and surface of he clothes re of your different rhe blood ; ; and the ater pipes, jvithin cer- lungs, and you know, nto vapor. 1 one is in 2 excess of ilied in the and forces in any one reater than »n free per- d parched, cooler and Darts of the that of the le man has le eats and ded by an •60 degrees .son of the ry vapor, a THE LARVNX — VOICE — SPEECH. 73 Force, power, or streng^th, 1 have referred to on several occasions ; but that part of physiology which relates to the source of the vital forces within the body, which give you power to exercise your muscles — which produce motion, is not very well understood. Heat is in some way converted into force or power. Heat itself, indeed, appears to be motion, more or less rapid, of the minutest particles or atoms of anything heated. If you put a bar of iron into burning coals, the particles of the iron are set in motion amongst each other, and if you take the bar in your hand the motion, rapid tliough invisible, is coumumicated to the delicate little nerves in the skin of your palm, and gives you pain ; — in popular language, your hand is burned. And so what we call heat, which is generated in your body, is in some way turned into a force, in virtue of which your muscles contract, your blood is sent to all parts of your body, and you are enabled to move about. THE LARYNX. — VOlCt. — SPEECH. The larynx, by the agency of which voice is produced, is the upper expanded part of the wind-pipe, and forms the promi- nence in the front of the neck, commonly called 'Adam's apple* (Fig. 42). It is formed of plates of cartilage, and is lined by mucous membrane. It is placed at the top of the wind-pipe, to take ad- vantage, as an exciting force, of the air forced out of the lungs during expiration. The vocal cords are tense, elastic membranes, which stretch across within the larynx, and form the boundaries of a chink, which is the only opening for the air to pass either into or out of the lungs. The chink or opening is called the glottis, and is in shape like the letter V, the cords coming almost together in front. By the action of little muscles, when about to use your voice, the cords are brought nearer together behind, and their edges are made par- allel. And when you force air out of your lungs it must pass through the larynx, and between these cords, causing them to vi- brate, and thus a musical note, the voice, is produced. A valve, the epiglottis, prevents the food entering the '•ynx (Fig. 42). The pitch of the voice depends on the tension of uie vocal cords — on the degree to which they are stretched by muscular action. Speech is the voice modulated by the tongue and lips as it passes through the mouth. You may produce voice without speech ; and you may speak without the voice, as in whispering. u ELEMENTARY ANATOMY AND PHYSIOLOGY. CHAPTER IX. DIGESTION AND ABSORPTION. Digestion is the function by which the foods we eat are made fit to mingle with the blood, and so feed the blood as the blood feeds the tissues. The foods are made into blood. It is only with the foods we eat, and oxygen, that the blood can be so nour- ished and renewed that it can continue to supply either the wants of the tissues, or fuel to burn and give us warmth and strength. Foods contain the elements which the blood and tissues require ; but they must all be brought into a fluid state, mingled thoroughly with the blood, and become a part of it, before they can be used by the tissues, and become a part of the body, or be burned as fuel. Meat, bread, and vegetables, as such, cannot be put right into the circulating blood ; and therefore in all animals. Special organs are provided for manufacturing the foods into fluids which can be mixed with the blood in the body and readily become a part of it. Organs, with cavities, as the stom- ach, for receiving the foods, are provided, and also other organs, as the teeth and certain bodies called glands, for breaking down the foods and making them into fluids. Some little animals have, as for a stomach, for holding the foods, only a simple pouch, with one opening, like the finger of a glove ; but the higher animal; have a tube passing quite through the body, called the alimentary canal. In some this canal is not any longer than the body, in others, as the sheep, it is thirty times as long. In man it is of medium length, and is much folded. The glands prepare, or extract from the blood, and pour into this canal, certain fluids or juices for mingling with the foods and liquefying or dissolving them ; or as it is called, digesting, which is as nearly as possi ble the same thing as dissolving, — to loosen, or bear apart, the minute particles of which anything is composed. Water, you know, readily dissolves many things, as sugar and salt. But water will not thus dissolve beef and bread. There are many things, however, which, when added to water, greatly increases its dissolving powers. The membranes of which the stomach of animals is formed always contain some of the stomach juice, in which, with water, is a peculiar ferment and some acids. If you put some bits of roast beef in a bottle containing water and! a piece of the stomach of a pig or a dog, and keep the mixture / it are made i the blood It is only be so nour- r the wants d strength, les require ; thoroughly :an be used ; burned as )e put right !s. ig the foods e body and LS the stora- ther organs, laking down limals have, pouch, with her animals e alimentary ;he body, in man it is of prepare, ori ain fluids or )r dissolving irly as possif ir apart, the| is sugar and I ead. There prater, greatly! )f which thel the stomadil I some acids. I ng water and! the mixtuiel It <^^ t '"T Fig. 41. Heart, lungs and 4f reat vessels ;— front view. A, A, aorta ; P, P, pulmonary ar- tery, right and left branches, the rifrlit passing behind tlio iiorta and superior vena cava, V ; L, L, left lung, with front edge turned bacit ; c, c, large arteries and veinsof the neck; T, tracliea. Front of right lung is cut a- way, sliowing divi- sions of artery. ^^ig- 43- Orgons of thorux, or chest, and abdon en, or belly, in po- sition. Pharynx, or throat, f ; b, oesopli.igus ; k, tongue ; c. trachea, or wind-pipe ; d, larynx ; e, epiglottis, a valve wliieh shuts down and closes the opening into tlie la- rynx and winl-iiipo when food iu being swallowed ; (^ scroll-liiie bone on outer wall of nostril, with filaments of nerve spread out abo^c it. DIGESTION. 75 Pk' 43- Orgons of thorux, or chest, and abdon en, or belly, in po- sitiuii. wx about blood warm, in a few hours' time the bits oi flesh will, as such, about all disappear, through the action of the juice from the piece of stomach, and you will have a solution of beef The alimentary canal, which passes through your body, com- mencing at your lips, is lined throughout with a skin very like the true skin of your body, but called mucous membrane (page 15). And when you take food into your stomach, which is simply an expanded part of this canal, the food is in reality still outside your body. It is only after it has been dissolved in the canal, by the aid of the digestive juices, and has passed into the blood, that it can be said to be inside. Something about foods : — A^I foods come under either one or the other of four heads ; they are either proteids, or they are fats, or they are amyloids, or they are minerals. The proteids all contain nitrogen, remember, with other elements. Hence they are call( d nitrogenous foods, to distinguish them from tiie fats and amy oids, which contain no nitrogen. Now the bodily tissues contain nitrogen, and the proteids are the only foods which can supply nutriment for renewing the tissues. Albumen, fibrine, caseine, and gelatine (page 10), are proteid substances; and so are such foods as flesh, milk, and eggs (which contain much proteid matter), and, to a less extent, bread. Fats consist of carbon, hydrogt^n, and oxygen, only. All animal and vegetable fats and oils come under this head. The amyloids, too, consist of car- bon, hydrogen, and oxygen, but they contain only so much hydro- gen as will form water with their oxygen, while fats contain an excess of hydrogen, and are therefore better for supplying heat and force ; which is the chief purpose of the fats and amyloids. Starch and sugar are the princi])al amyloids. Water and the various salts are the mineral foods. Most ordinary food-stuffs contain two or more of these alimen- tary principles of foods. Meat, milk, and eggs, contain proteid and fatty matters and salts. Bread, though consisting largely of starch, contains considerable proteid matter, salts, and traces of fat. Potatoes are nearly all starch. Most fruits con lain consid- erable sugar, with seme proteid matter. Foods are mixed with some substances which are not soluble in the digestive fluids ; such as the skins and some seeds of fruits and vegetables, and the sheaths of fibres in flesh. The digestive apparatus consists then of the alimentary canal and certain bodies, called glands, which produce juices for dissolving the foods. Different parts of the canal are known 7« ELEMENTARY ANATOMY AND PH\SIOLOGY. i ! by different names, as the n. = th, throat, gullet, stomach, and intestines (Figs. 42, 43). The mouth is closed in front by the lips, and at the sides by the cheeks. It contains the organ of taste, for guiding us in the selection of food, and the teeth, for biting off and grinding por- tions of food. The teeth are fitted in sockets in the borders of the jaw-bones, which project into the mouth ; and the jaws are here covered with thick, tough, mucous membrane, forming the gums. Hanging down from the roof of the mouth, behind, is the teat-like uvula ; and on each side of this are two curved folds or ■arches of mucous membrane, between which is the tonsil. The permanent teeth, of adult Hfe, number thirty-two ;— four front teeth, or incisors, two eye teeth, or canines, four bicus- pids, and six m irs, in each jaw. The molars have each three tools, the bicuspids two, and the others only one, which fit into the sockets in the jaw. The part of the tooth above the gum, the cro7un, is covered by a very hard and dense namel, which, remember, when once destroyed is never renewed. In the crown is a cavity which is continued to the point of the root, and con- tains a nerve, blood-vessels, and fatty tissue, called pulp, "^h^ temporary teeth, of infancy, numbc" only twenty, and are usual!' shed between ;lie sixth and fourteenih years. The throat, or pharynx, the back wall of which you see on looking into the widely open mouth, is a muscular tube extending from the skull down through the neck. The nostrils and eusta- chian tubes (of the ears) open into it above, and below, behind and underneath the tongue,is the open- ing into the larynx, the glottis, which ad- mits air to the lungs (Fig. 42). At this opening is a valve, the epiglottis, which shuts down over the opening when we swallow, and prevents food entering the wind-pipe. The gullet, or oesopha- gUS, is like a continuation of the pha- rynx, and extends down through the chest, behind the wind-pipe, pierces the diaphragm, and opens into thestomach. The stomach (Fig. 44) is a great expansion of the alimentary canal, in the upper part of the abdomen, chiefly in the left side. V. here it joins the intestine there is a valve, Pyloric valve (pylorus^ a gate), which closes the canal during certain Stomucli, in section (inside of), A ; B to C, (luodcnuni ; 1>, j^iillet ; E, irall-hladdor ; F, hepatic dnct (to liver), unitinjr with pancreatic (iuct, G, before opening into intestine. macb, and he sides by g us in the nding por- borders of le jaws are Drming the hind, is the ed folds or 'il. irty-two ;— four bkus- each three ich fit into ; the gum, mel, which, I the crown t, and con- tidp. Ti,. are visual' you see on I extending and eusta- ow, behind is the open- s, which ad- 2). At this ottis, which ig when we entering the r cesopha- of the pha- hrough the , pierces the he stomach. \) is a great ry canal, in nen, chiefly is a valve, ring certain DIGESTION. 77 periods of digestion in the stomach. The next part of the canal is called the small intestine, vvhich is about twenty-five feet in length, and much fi Ided. The first part of it forms a peculiar curve, and is a sort of second stomach, called the duodenum (Fig. 44). Two important digestive fluids — bile and pancreatic juice, are emptied into this, by little tubes leading from the liver and an organ called the pancreas. Below, the small intestine opens into the large intestine, or colon. This extends from the lower part of the right side of the abdomen, up to the stomach, crosses to the left side, and then descends to the lower outlet (Fig. 43). The sides or walls of the alimentaiy canal are made up of three distinct layers or coats of membrane, one upon the other. The mucous coat, resembling the outer skin, which lines it, from end to end, we have already noticed. The layer of cells on this, called epithelium (page 15), which on the outer skin would be called cuticle, varies in character in the different divisions of the canal, It is much thinner than the cuticle, and much of it con- sists of only one layer of cells, like that covering the villus (Fig. 45), instead of many layers, like the cuticle (Fig. 49). And this thinness of the ei)ithelium is the cause of the skin of the mouth and other parts of the canal being always red and moist, and not pink and dry, like the skin of your hand. The redness of the blood in the numerous capillaries beneath is seen much more dis- tinctly through the thin epithelium than through the thick cuticle. You know if you shave or rub off the thin surface of your skin anywhere the skin gets redder. Moisture, too, from the blood finds its way more freely through the thin epithelium. In the stomach and intestines the mucous coat is soft and more or less folded or wrinkled. Hanging from its surface, as it were, in the small intestine, are myriads of minute projections, resembling the pile of velvet, called villi. The muscular coat lies next the mucous coat, and commences at the lips. Some of its fibres extend lengthways and others encircle the canal. By the con- traction of these fibres the contents of the canal are gradually moved onward. The serous coat is outside the other two, as regards the canal, but really on the inside. It is an immense membrane, and besides investing most of the canal, and the liver, it lines the walls of the abdominal cavity ; and being very smooth — as you will find the intestines of any animal — it prevents friction. It also keeps the parts in proper position. You should get a piece of both the stomach and intestine of a pig and dissect them carefully. hi I 78 ELEMENTARY ANATOMY AND PHYSIOLOGY. Fig. 46. The villi, above referred to (Fig. 45), which hang from the mucous surface, are not unlike papillae of the skin (Fig. 25), but are longer and covered with only one layer of cells. Just be- neath the cells is a net-work of blood capillaries, as in the papillae. But besides this, each villus contains, what a papilla does not, a minute tube, commencing like the rootlet of a plant, called a lacteal. I'he villi suck up or absorb the digested food from the intestine. The glands connected with digestion are very numerous. Most of them are small and in the _ _ substance of the mucous membrane lining the ali- A Villus. A, lac- mentory canal ; just as the sweat glands, as you will teal tube, surrounded jgarn by-and-byc, are in the substance of the skin. capiUaries connecting Besidcs thesc, there are the much larger salivary i^'anfc'Way^ of glands, near the mouth, the still larger pancreas, epithelium cells. near the stomach, and the huge liver ; all similar in structure. The simplest of the glands each consists of a minute tube, closed at one end, like the finger of a glove, and lined with a layer of epithelium cells (Fig. 47). The larger glands are made up of many tubes, or branch tubes, the branch tubes ending in Fig 46. closed swollen ends (Fig. 46) : indeed, in structure, very like a lung. The largest trunk tube, which may be compared to the windpipe, is called the duct of the gland (duco, to lead), and leads or conveys out the fluid formed in the gland. All the tubes and branches are lined to their closed ends with a layer of epithelium, and are wrapped round with net-works of capillaries, and all are held and packed closely together with connective tissue. In each gland, from the blood flowing in the capil- lary net-works around the tubes, a certain fluid sub- view of structm^e of stance is attracted, or passes by osmosis, into the glands of intestine, tubes, and, increasing in quantity, flows into the larger branches and out along the duct. The fluid is called a secre- tion. And it is said to be secreted by the gland. Different sorts of glands, as you will learn, take from the blood or secrete very different sorts of fluids. The largest of the salivary glands, the parotid gland, is just beneath the skin under the ear, behind the jaw (one on each side). Its duct leads forward and opens at the inner side of the cheek, DIGESTION. 79 S), which ot unlike )nger and Just be- apillaries, ach villus uite tube, t, called a B digested istion are and in the ig the ali- as you will f the skin. salivary ancreas, all similar f a minute lined with are made ending in I structure, ivhich may the duct OT conveys the tubes nds with a round with ,nd packed n the capil- 1 fluid sub- s, into the 's into the d a secre- Different or secrete ind, is just each side), the cheek, where its secretion is poured into the mouth. At the inr jr side of each lower jaw is another similar body, ':he submax- Fig. 47. illary gland, the duct of which empties its secretion into the mouth under the tongue. Two others, sublingual glands, are under the mucous membrane of the floor of the mouth. In the abdomen, behind the stomach, is a gland, five or six inches long, called the pancreas (the sweet dread of a.nimah) ; a duct conveys its secretion into the duodenum. When the mucous membrane of the stomach is stretched, the openings or mouths of its nu- merous little glands, here called gastric follicles, may be seen with the unaided eye. In the small intestine the openings of the glands are concealed by the villi. The liver, with the appearance of which, in animals, ',|^^^*ghQ^.' you must be familiar, is made up of a vast number of inKia.vcr of minute glands, or lobules^ connected together by branches eeu's^near of its duct, blood vessels, and connective tissue. It is itstnouth. much the largest gland in your body, flattened, and stretched across the upper part of the abdominal cavity, from the right nearly to the left side, close to the diaphragm. Its blood vessels, of which it has three sets, and its duct, enter or proceed from its under surface, all near together. You should examine a liver, cutting into it, and using a small magnifying glass. You remember that the blood in returning toward the lieart from the stomach, intestines, and some other organs, mstead of being conveyed direct to the vena cava, is collected by ihe portal vein (Fig. 36) and carried to the liver, and through a third set of capillaries (page 61), into which this vein breaks up, in the little lobules of the liver. The hepatic artery (hepar, liver) supplies the tissues of the organ with fresh arterial blood. And hepatic veins collect the blood from the capillaries, observe, of both the portal vein and hepatic artery, and convey it into the vena cava. From the venous blood in the net-works of capillaries around the little tubes in the lobules, bile (or the materials for making it) passes into the little tubes, accumulates, and flows into the hepatic dtict^ by which it is conveyed out of the liver, and to the duodenum. A pear-shaped sac, the gall bladder^ on the under surface of the liver, serves as a reservoir for any excess of bile (Fig. 44). The digestive fluids, secreted by these gland.s, are, the saliva, gastric (stomach) juice, intestinal juice, pancreatic juice, and bile. The mixed saliva, of the salivary glands, is a watery fluid, and contains a peculiar sort of ferment (piyaline). It is poured into 8o ELEMENTARY ANATOMY AND PHYSIOLOGY. the mouth in considerable quantities while the food is being ground or chewed. The expectation of food, even, you know, sometimes * makes the mouth water,' — excites these glands, through nervous influence, and they pour out their secretion. Saliva lias a wonderful power of converting starch into sugar, which is very soluble, though starch is not. It you hold in your mouth some thick, sticky, boiled starch, in a little ti;vje it will become quite sweet, from the presence of sugar. Gastric juice oozes freely from the mouths of the gastric follicles, directly food reaches the stomach. This fluid is acid (sourish), and contains a peculiar substance, called pepsin. It has great power in dissolving proteid matters, as meat, curd of milk, and white of egg (page 75). Pancreatic juice is a viscid, colorless fluid, which, like saliva, converts starch into sugar; while it has also a special action upon fats. The intestinal juice dissolves proteid matters much as gastric juice does. Bile is a thickish, stringy fluid, of a greenish yellow color, nauseous smell, and bitter taste. It and the pancreatic juice together dissolve the fats. Oil and water, you know, do not mix well together. But if you shake some oil with bile and pancreatic juice, a milky fluid is formed, which will mix with water and pass readily through membranes. When pancreatic juice and bile cannot get into the intestine, the fiits eaten remain undigested in the intestine a long time and finally pass out as useless. Why do the glands pour out their secretions as they do, just when these are needed by the foods in the canal? Your will has nothing to do with it : but your nerves have. The pre- sence of food in any part of the canal stimulates little nerve fila- ments, chiefly of the sympathetic (pages 20, 22), in the mucous membrane of the part, and an impression is conveyed by them to a ganglion — a centre, from which an impulse is sent back, by other filament; , to the glands, and they form and pour out their secretions. The sensations of hunger and thirst probably arise through a want of nutrient matter and fluids in the blood, or perhaps in the tissues, and are conveyed to the brain by certain sensory nerve fibres of the cranio-spinal system. In response to these sensations — to satisfy these cravings of nature, you eat food and drink water. The foods you eat are treated as follows : — You bite off a morsel, and while you grind or masticate it, chiefly with your molars, saliva is poured into the mouth in abundance, at both is being ou know, e glands, secretion, ito sugar. Id in your ;v>e it will trie juice ectly food contains a dissolving (page 75), ike saliva, ction upon s much as low color, eatic juice io not mix pancreatic r and pass I and bile digested in 3. ►ns as they lal ? Your The pre- I nerve fila- he mucous by them to t back, by ir out their jably arise : blood, or by certain response to ou eat food Von bite off Y with your ce, at both DIGESTION. 8l sides of the teeth. The saliva, with more or less air w/iich enters the mouth, is mingled with the food, which is then col- lected into a lump, or bolus, on the tongue. If the food con- tains starch, and most vegetable foods contain starch, its diges ( has already commenced ; a part of the starch has been converted into sugar. The tongue, with the bolus of food upon it, is now moved back and pressed against the roof of the mouth, com- mencing at the point, and the food is forced into the pharynx. The sides of the arch of mucous membrane at the throat come together and prevent the food passing up into the nostrils, while the backward movement of the tongue causes the epiglottis to shut down over the glottis and prevent it getting into the wind- pipe. The muscular fibres of the pharynx, and later, of the gullet, contract from above downward, causing a sort of wavy or wormy movement in the walls of the canal, commencing above the bolus, and it is forced quickly down — swallowed, and enters the stomach. These acts are repeated with other morsels of food until you have eaten all you want. The food is retained in the stomach for a time, longer or shorter, according to the nature of the food, the quantity eaten, and the degree ot fineness to which it has been ground by the teeth. The muscular fibres of the stomach produce a sort of rolling or churning movement of the organ, which mingles the food thoroughly with the gastric juice poured into it from the follicles. The proteid parts are thus gradually dissolved, and portions of them, at least, probably pass at once, by osmosis, into the numerous capillaries in the mucous membrane of the stomach, and mingle directly with the blood, ..hich is forever moving in these vessels. Som.c sugar, too, gels into the blood in this way. The remainder of the proteids and sugar, the fats and the starch, all now forming a tawny yellow mixture, called chyme, are poured into the duodenum. Here, any proteids not dissolved in the stomach are disposed of by the intestinal juice ; the remainder of the starch is dissolved by the pancreatic juice ; the pancreatic juice and bile together dissolve the fats. And the whole now form a creamy fluid, called chyle. By the action of the muscular fibres in the walls of the intestine, the chyle is moved along, and little by little its goodness is sucked up by the blood vessels and lacteal tubes in the villi. The villi, standing out from the mucous membrane, actually bathe in the chyle. How the fatty portions, in the la<_teals, reach the blood you will learn presently, when I tell you something about the function called absorption. And 82 ELEMENTARY ANATOMY AND PHYSIOLOGY. II thus, as the creamy mass, made from the food you had eaten, moves on, it gradually loses its nutrient particles ; until at last, all the undigested and superfluous parts are cast out of the body. ABSORPTION AND THE LYMPHATICS. Absorption means to suck or take in. All organized bodies live and grow by absorbing matter from without and mak- ing it a part of their bodies. Absorption takes place by virtue of the property of osmosis, by which fluids pass through membranes, and about which you have learned something already (page 55). Membranes permit some fluids to pass through their pores more freely than others ; and the nature of the membrane influences the direction in which a fluid will pass through it most freely. If you attach a narrow glass tube to a small bladder filled with alcohol, and fix the bladder in a vessel of water, water will pass by osmosis into the bladder and mingle with the alcohol {end- osmosis) ; while at the same time alcohol will pass out of the bladder into the water f'^jfosmosis). The water however will pass in more rapidly than the alcohol will pass out, — the membrane appears to have a greater attraction for water than for alcohol, water wets the inside of its little pores most readily — and the fluid will accumulate in the bladder, rise to the top of the tube, and flow over. If, on the other hand, you fill the bladder with water and place it in alcohol, it will soon become partially empty. If, instead of alcohol, you use syrup or gum water, the same results follow. Now the chyle in the intestine is absorbed by the villi hanging from the mucous membrane lining the intestine, and passes into the fiapillaries and lacteals, — the fatty parts are drawn into the lacteals and forced up the tubes toward a common cen- tral receptacle, by the same sort of force which draws water into the bladder and raises the fluid in the tube attached to it And by the same sort offeree, too, in the vegetable world, moisture is absorbed, and sap is raised to the leaves of the loftiest trees, along minuie tubes leading from little bladders in the rootlets in the moist soil. Lymphatics. — In most parts of your body (excepting the brain, spinal cord, and bones) there are, besides the blood capil- laries, numerous minute, delicate tubes, containing a thin, color- less fluid. The fluid is called lymph (from lympha, water), and the little tubes are called lymphatics, or absorbents. Within the tubes are numerous valves, resembling those of veins, and the ABSORPTION. 83 ad eaten, at last, the body. organized and male- virtue of embranes, page S5). 3res more influences freely, filled with will pass ohol (end- nit of the T will pass membrane )r alcohol, I — and the ■ the tube, adder with ally empty. the same by the villi istine, and are drawn mmon cen- raws water iched to it d, moisture tiest trees, rootlets in epting the lood capil- thin, color- ivater), and S. Within ns, and the lymph ca only flow toward the centre of the body. The lymph- atics are most numerous in the skin, mucous membrane, and sur- face of organs, and they all seem to start out of the tissues like the rootlets of a plant in the soil ; and like these, and the rootlets of veins, they join together and form larger tubes, which, for the most part, follow the course of the veins, and nearly all join at last in a great trunk, about the size of a goose-quill, in the upper and back part of the abdomen, called the thoracic duct. Now the lactealSy observe, are simply lymphatics which have their roots in the villi of the intestine. And they are called lac- teals (from lactis, milk) because during the digestion of fatty foods they contain the milky chyle. At other times, or when no fat is eaten, or when, from any cause, fat is not dige.sted, they contain colorless lymph, like other lymphatics. They all join together, too, and form larger trunks which empty Fig, 43. into the thoracic duct (Fig. 48). This duct, oddly enough, passes up through the chest and empties its contents — chyle and lymph, into the great veins of the neck. And this is how the fatty parts of the chyle, at least, if not other parts, get into the blood and keep it nourished and renewed. Bodies called lymphatic glands are found at numerous points in the course of the lymphatics and lacteals (Fig. 48). They consist of a net-work or cluster of lymphatics associated with a net-work of capillaries. You can usu- ally feel one or more of the largest of duct, b ; c, lymphatics ; d, aorta these beneath the skin under the arm, or in the groin. The function of the lymphatics is not altogether understood. Probably the more watery part of the blood, after passing through the capillary walls and carrying with it nutrient matter to the little islets of tissues, may, after giving up this nutrient matter, be re- ceived more readily into these new channels (the lymphatics) than into those it had just left. And with it some of the waste matters may be returned to the blood, at the neck, to be again utilized in the circulation. Both lymph and chyle, after passing through lym- phatic glands, contain colorless, globular cells, or corpuscles, quite like the colorless corpuscles of blood. And these are regarded as the * mother cells' from which blood corpuscles are formed. A, portion of Bmall intestine, with lacteals luadint; from it to thoracic 84 ELEMENTARY ANATOMY AND PHYSIOLOGY. CHAPTKR X. ■ - ^ SECRETION AND EXCRETION. About all that remains now to be told about your body refers to the getting rid of the waste matters — the products of wear and tear and combustion. Were these not removed continually, as they are produced, your whole organism would soon be so choked that it could not perform its functions. The waste matters are chiefly water, carbonic acid, and ammonia (nitrogen and hydrogen, combined), and some salts. The body is built up of many elements (page 13), and when it is broken down, in whatever way, these elements, and these only, are the products, though they form various combinations. Whe- ther it be burned quickly in a furnace, or be slowly consumed by oxidation in the grave after death, or be oxidised or burned gra- dually by living arterial blood, the products are all the same. Besides such waste matters, there are the indigestible parts, and any excess, of foods eaten. And lastly, a large quantity of water is consumed with drinks of one kind and another, which besides aiding in digesting the foods and keeping the blood sufficiently fluid, dissolves and washes out waste matters. You have, so to speak, a continuous stream of water passing through your body, washing away impurities ; and you have to get rid of this washing water as well as the water arising from the burning of food. The organs which throw off the waste matters are the ungs, the glands of the skin, and two familiar glands, called kid- neys. You have already learned that a great deal of carbonic acid, watery vapor, and some other matters, are thrown out by the lungs. You remember what a gland is, — a tube or tubes wrap- ped round with net-works of capillaries — and that it takes from the blood a certain fluid substance, called a secretion. The secretions of many glands, as those of digestion, as you have learned, are retained and used in the body ; but the secretions of the glands we are about to consider are cast out of the body, and hence they are usually called excretions (ex, out of). The lungs are, in one sense, excretory glands, which excrete carbonic acid and watei. GLANDS OF THE SKIN, AND THE PERSPIRATIONS. The skin has been briefly described at page 15. The outer layer, or coat, of cells, the cuticle, — which you can shave off dy refers kvear and ually, as ) choked cid, and me salts, ^hen it is ese only, s. Whe- lumed by rned gra- he same. )arts, and r of water n besides Litficiently Lve, so to jur body, s washing 3d. •S are the ailed kid- carbonic >ut by the Des wrap- 5 from the jccretions irned, are le glands ence they gs are, in ,nd watei. s. rhe outer shave off SECRKTION AND KXCRETION. 85 without giving pain or * drawing' blood, because it contains neither nerves nor blood vessels — affords great |)rotection to the coat be- neath, the cutis, which is made up almost entirely of nerves, blood vessels, glands, and strong connective tissue. The nails and hairs are composed of hardened cells, which gradually coal- esce into the horny continuous plate of the nail, or the shaft of the hair. They are in fact continuations of the cuticle. The sweat glands are each composed of a minute tube, lined with epithelium. One end is closed, and coiled into a sort of knot, in the deepest part of the skin, and is interlaced with a net-work of capillaries ; the other end serves as a duct, and passes out through the skin to the c-uter surface, upon which it opens (Fig. 49). The openings of these glands are known as the j 'pores' of the skin. It is estimated that in the skin of I the palm and sole there are between two thousand and three thousand of these glands to the square inch of] surface ; and that in the skin of the whole body there are over two millions of them. They are greatly under the influence of the nervous system. A watery fluid, the sweat, or perspiration, is always passing from the blood in the capillaries into the tubes and escaping at their open ends upon the surface of the skin. The perspiration consists chiefly of water, with some salts dissolved in it, and a small quantity of car- bonic acid and nitrogenous and fatty matters. It is passing off continuously in small quantities without you knowing it, as it escapes quickly by evaporation through ^|j."^ ^'c" "u- your clothes into the air; and hence this is called in- tis- d. sweat sensible perspiration. When from exercise or other fonUliiSt^E! cause the capillaries of the glands get over-full of blood, 'at cells, the excretion becomes so abundant that it accumulates in drops on the skin, and is called sensible perspiration. The amount of this varies immensely. By means of it alone, heat and violent exercise may reduce the weight of the body two or three pounds in an hour. Not only is the heat of the body kept within certain limits, and regulated, by the perspiration, as you have learned (page 72), but with it a great quantity of waste matter is carried out of the body. The glands of the skin therefore help greatly to purify the blood. Sebaceous glands, simple, pouch-like bodies, are found in most parts of the skin, the ducts of which usually open beside the hairs. They secrete an oily substance which serves to keep the cuticle and hairs soft and pliable. Suction IMAGE EVALUATION TEST TARGET (MT-3) 1.0 I.I 1.25 IIIM 112.5 illM 2.0 12.2 111— 14 III 1.6 V] (^ n / '/ /A / ^c>T" .>' / o 7 Photographic Sciences Corporation 23 WEST MAIN STREET WEBSTER, NY. MS80 (716) 872-4503 ^ \ iV '^v\ V % v "^ % V %^ 6^ Si" C^x W ///// ^^ k 36 ELEMENTARY ANATOMY AND PHYSIOLOGY. THE KIDNEYS AND THEIR SECRETION. The kidneys are two bean-shaped glands, placed against the back wall of the abdominal cavity, and with the appearance of which, in animals, you are probably familiar. Large branches of the aorta supply them freely with blood. Each kidney consists Fig. 50. of many long tubes, not very unlike the sweat glands, much folded and interlaced with capillaries, and all arranged and bound together in a most beautiful and regular way. The tubes all open into a common central cavity, from which r large lube, the ureter, conveys their secretion to a receptacle, call- ed the urinary bladder (Fig. 50). Urine is secreted — separated from the blood, by the tubes in the kidney, just as sweat is secreted by the sweat glands, and flows into the central cavity, and hence down the ure- ter into the bladder, to be cast out at in- tervals. It is water holding in solution various salts, chief of which is ammonia in combination with a little carbonic acid, Kidneys, K. K; bladder, B; forming what is called urea. U, ureters ; A, aorta ; V, vein. The lungS, the glaudS Of the Skill, and the kidneys, then, are the three great channels by which the blood gets rid of its waste matters and purifies itself. Each organ ■consists, fundamentally, of a moist, thin membrane, which separates the blood from the atmosphere ; and water, carbonic acid, and urea, are the three principal forms of waste matters, which pass out of the blood through the membranes. As the blood in its rounds passes through these organs, little by little it gets rid of the waste matters, and returns from each purer and fresher. But, observe, to get rid of carbonic acid and some poisonous organic matter — as well as to obtain oxygen — is the most important, and hence at every round of the circulation all the blood passes through the lungs, while only a small part of it passes through the skin and kidneys. There are in the body several soft, glandular organs, without special ducts, called ductless glands, the functions of which are not well understood. The spleen, in the left side, is the most important of these, and is believed to have something to do with the blood corpuscles. against the pearance of branches of ley consists unlike the d interlaced i and bound regular way. men central the ureter, eptacle, call- 50). Urine le blood, by as sweat is id flows into own the ure- st out at in- in solution ammonia in rbonic acid, f the skin, jy which the Each organ ch separates ic acid, and which pass blood in its its rid of the esher. But, lous organic portant, and sses through the skin and lans, without of which are is the most g to do with PART II. ELEMENTARY HYGIENE CHAPTER XI. PRELIMINARY :— HEALTH AND DISEASE ;— CAUSES OF DIS- EASE, INSIDIOUS NATURE OF ;— VALUE OF HYGIENE. In the first part of this book we examined the structure and functions of the various parts and organs of the body when in a natural healthy state. I^et us now, in this part, enquire into, and study the nature of, those essentials of life — those agencies, by which a healthy state is preserved and life prolonged. Health is that condition in which all actions or functions proper to the body are performed in the most perfect and har- monious manner. This necessitates a perfect and natural state of the organs of the body. The perversion or partial cessation of one or more of the functions or processes of life constitutes disease. And anything which prevents, or interferes with, the perfect and harmonious performance of these functions, or which obstructs any of the vital processes, is a cause of disease. The continued operation of any such cause will sooner or later give rise to altered organic structure, and we then have diseased organs as well as diseased functions. Health is an active, uninterrupted renewal of the worn parts of the body, and a prompt throwing off of all the worn-out, waste substances, giving rise to the most active life in every part and organ. Disease has been termed a partial death. The human organization is of the highest com- plexity, and is therefore very liable to derangement, and its func- tions to perversion, by the many and various causes of disease by which we are surrounded. We will now briefly notice the nature of these causes. The essential conditions of health and of life, as I have told you (page 12), are a supply of air, water, and food, and also sleep, clothing, exercise, and bathing, without some of which you cannot live. These conditions or agencies of health and life are, as you know, very liable to changes. The air around you becomes impure from your breath ; foods are 5 ■T^Pi 88 ELEMENTARY HYGIENE. often improperly prepared ; or one may take too much or too little exercise. Now as the functions of your body are directly dependent upon these agencies, when any one of them is dete- riorated, or not good and appropriate, it is at once a cause of disease, and more or less functional derangement — disease, will assuredly speedily follow its use. Nearly all causes of disease, and of premature death, are, in fact, intimately associated with these agencies or essentials of life; or, in other words, they are to be found in perverted conditions of these agencies, which of necessity we are con- tinually making use of. Breathing foul air, drinking impure water, eating bad or too much food, too little sleep, improper clothing, or want of exercise and perfect cleanliness, each and all interfere directly, more or less, with the natural or healthy actions of the organism, and cause disease. Moreover, a very large pro- portion of the causes of disease arise from the imperfect manner in which the waste matters from our own bodies are disposed of; from these waste matters being conveyed back into our bodies again, and chiefly along with the air and water consumed. Many persons, in their bedrooms, breathe — take into their lungs, over and over again, air laden with excrement given off by the lungs and skin, a highly injurious practice, as you will learn by-and-by, and a very common cause of disease. Other excrete matters from the body are often thrown in proximity to wells of water, and hence find their way into the water, and with it get back into the system. These waste matters, if not absolutely poisonous when thrown off, soon undergo changes and become in many cases highly deleterious. All in the long list of contagious dis- eases — small-pox, cholera, scarlet-fever, typhoid, and the like — are often spread, and therefore may be said to arise, in this way. The contagion is in the excrete matters, and if these are not properly disposed of, as by free ventilation and disinfection, such diseases will readily spread to other persons. The contagion is conveyed to others usually with the air or water, sometimes with foods. Besides the above causes of disease, there are what may be called climatic causes — sudden changes in the state of the atmos- phere or weather, mental or emotional causes, and hereditary causes — those inherited from parents, over all of which we have less control. Nevertheless, with proper regard to the state of the skin, and to the clothing and other agencies, climatic causes would be almost inoperative ; and by careful attention to the laws of GENERAL PRELIMINARY REMARKS. 89 ch or too e directly n is dete- cause of sease, will ieath, are, essentials perverted are con- jg impure improper .ch and all ;hy actions large pro- ;ct manner sposed of; 3ur bodies ed. Many lungs, over the lungs by-and-by, atters from water, and back into poisonous e in many agious dis- the like— [1 this way. :se are not iisinfection, e contagion sometimes hat may be [ the atmos- hereditary ich we have state of the auses would the laws of health generall)', hereditary causes and hereditary diseases would disappear in a few generations, and diseases arising from mental or emotional causes would be rare. By means of knowledge regarding the nature of these agencies in all their varying condition^^ and of their relations to, and effects upon, the organs and functions of your body, you are enabled to control the causes which disturb and pervert these or- gans and functions, and thus prevent disease. Happily, it is much easier for you — much less knowledge is required — to take care of and preserve your health, than to regain it when lost ; to keep your organs and functions in a perfect and healthy condition, than to get them into such condition again after they have become deranged or perverted. When the parts and their functions become altered from their natural state, the most ex- tended knowledge and profound skill and experience may be required to set them right again, if indeed it be possible to set them right, as it may not be. You have, then, in your own hands, to a great extent, the power to prevent disease and to pro- long your life, which disease might greatly shorten. A high remedial value, too, attaches to hygienic measures ; and in all diseases their practical application is of the first im- portance. On the near approach or actual occurrence of disease, the prompt removal and avoidance of all causes, as well those which gave rise to the disease as all others, will very materially assist in restoring health. There is in our bodies a tendency toward perfection ; a tendency to set matters right when they have gone wrong ; in disease, a natural inclination to health. Hygienic remedies assist this natural effort, and are sometimes sufficient to restore health. Sometimes medicine is required. But one should never take any medicine, commonly so called, except under the advice of a physician, because the simplest of them might interfere with, rather than assist, the natural efforts. Besides, you should know, physicians rely much less on drug medicines now than they did in earlier times. False ideas regarding disease have in times past proved unfavorable to hygienic effort, and operated against the employ- ment of means to prevent disease. In early ages diseases were believed to be due to evil spirits which in some mysterious man- ner found their way into the system. Many now regard disease as something having an independent existence ; something to be thrust out of the system by medicine ; something that comes arbi- trarily, or is ' sent ' by Divine Providence as punishment for '!< I 90 ELEMENTARY HYGIENE. sins committed. Many of the semi-religious story books now in libraries for the young, teach or convey these erroneous ideas. True, diseases come because of our transgressions, not of the moral laws exactly, but rather of the simple physical laws of health. VVe bring them upon ourselves, for the most part, by our own acts or neglects. Since more enlightened views have somewhat prevailed, there have been numerous proofs of the great benefits to health and vitality from giving practical attention to the laws of health, to the condition of the essentials or agencies of life —air, water, food, etc. It must be borne in mind that the injurious effects on the organism of any of these causes of disease are not always, or even usually, immediately perceivable, but are frequently slow and cumulative, and not noticeable until much mischief has been done. The breathing of air contaminated by the products of respiration, as in unventilated rooms, is believed to be a common cause of that most fatal of all diseases, consumption. Yet, this disease, so caused, often arises and increases so impercep- tibly, that it is not manifested until too late to be remedied. So, intemperance, in both drinking and eating, is a very common cause of disease. Yet the diseases arising therefrom do not commonly attract attention until the intemperate habits have been indulged in for a long time, perhaps not until serious organic disease has been produced. Pain, in some form or degree, whether severe or only amount- ing to slight uneasiness, is the most common symptom of disease, and not unfrequently acts as a kindly monitor to warn us that something is going wrong in our body, or that we have com- mitted some error. Intelligence that something is wrong is con- veyed to the brain by sensory nerve fibres (page 22). But we are not always thus warned. Causes of disease may continue to act, and produce effects of a more or less serious or permanent character, without causing pain or giving us any warning whatever. One thing is certain, that is, causes always produce effects ; and this ought never to be forgotten. If we breathe foul air, or use bad water or improper food, some ill effect is certain to follow ; though it may not be appreciable to our senses, or possibly not of a permanent character. We will now consider separately each of those essential vital agencies, and the effects of them, in their various conditions, upon the body or the health. AIR AND riEALTH. 9^ i now in s ideas, t of the laws of part, by ws hftve fs of the attention agencies s on the Iways, or itly slow has been )ducts of common n. Yet, mpercep- •emedied. common 1 do not oits have is organic f amount- )f disease, a us that lave com- ng is con- But we continue jermanent whatever, fects ; and air, or use to follow; )ssibly not jntial vital ions, upon CHAPTER XII. THE AIR AS REGARDS HEALTH. Pure atmospheric air consists of nearly 21 parts, by volume, of oxygen, about 79 parts of nitrogen, .033 parts of carbonic acid gas (carbon dioxide), and minute traces of ammonia and vapors of sodium salts ; it always contains watery vapor — which varies much in quantity — and, usually, traces of ozone. Oxygen is the life sustaining element, a considerable proportion of that continually entering the lungs being used in the body. Nitrogen may be regarded as serving to dilute the oxygen. The carbonic acid is absorbed by plants. Ozone is regarded as nature's great disinfectant and deodorizer. Dr. Parkes infers that the highest degree of health is only possible when to other conditions is added that of a proper sup- ply of pure air. The supply of air is practically unlimited, an immense ocean of it, many miles in depth, surrounds the earth, and we may always have it in abundance, fresh and pure. The impurities which find their way into the air are very numerous ; but a wonderful series of processes goes on in the outer atmosphere, or on the earth, which preserves it in a state of purity. It is in enclosed spaces — rooms, schools, shops, factories, and close yards, where these purifi ing processes are not in full operation, that the air becomes impure and too fre- quently quite unfitted for respiratory purposes ; as it does also near collections of decomposing organic matters, which rapidly foul the air. The habitations and works of man, in a hygienic point of view, furnish the most important impurities in the air. These are : — the products of respiration, effluvia from decomposing filth near dwellings, and sewer gases ; emanations from work in factories, such as the grinding of steel, stones, and paints, and carding and spinning textile fabrics, the manufacture of flour, and of friction matches ; in rooms, the coloring matters from wall papers, the products of lighting and warming, and particles from the skin and clothing. In the outer atmosphere are vapors from marshes and decomposing vegetable and animal substances, particles of soil, germs, spores, bacteria, and numerous living creatures. But here, noxious matters are usually rapidly destroyed by free dilution, diffusion, and oxidation. ITT 93 ELEMENTARY HYGIENE. Air vitiated by respiration and perspiration, in dwellings, shops, schools, etc., from want of free ventilation, is probably more generally injurious — productive of more disease, than air in any other condition. Expired air, as it passes from your lungs, as you have been told, contains a large amount of carbonic acid, — about seventy-five times as much, indeed, as ordinary air. It also contains a large proportion of moisture ; while the oxygen has been very materially diminished, and its value thus lessened. And most important of all, it contains an 'organic' compound which, when re breathed in large quantities, produces most perni- cious eflfects upon the body. Detached cells from the mucous surface of the air passages are also in expired air. By the skin, too, much moisture is given off, as perspiration, and with it fatty matters, epidermic cells, and other impurities. You may readily understand now, and know, that the air very quickly becomes foul in a close room occupied by two or three persons. The organic matter in expired air has a peculiar, very letid smell, and when it is passed through water, this is rendered very offensive. The fetid odor in unventilated bed-rooms and crowded rooms is owing to this impurity. It is nitrogenous, yielding ammonia on decomposition, and is but slowly oxidized, and seems to float in clouds like tobacco smoke. It is most readily absorbed by wool, feathers, and damp walls ; and has been found in large quantities in the plaster removed from the walls of hospital wards. The bare thought of inhaling the above substances from the lungs and skin of another person, or even from our own, is very repulsive. Yet they are being constantly and universally breathed by all classes. In the open air, or in well ventilated rooms, they are quickly dissipated and rendered innoxious by oxidation. The effluvia from sewers, cesspools, middens, and all collections of fecal matter, consist of a number of gases and vapors, among which are sulphuretted and carburetted hydrogen, carbonic acid, and ammonium sulphide. The peculiar fetid smell of the effluvia is due to the presence of an organic com- pound ; this quickly taints meat and sours milk, and promotes the growth of fungus plants. These poisonous gases are very light, and therefore tend to the highest points. Into houses connected with sewers they frequently find their way ; passing through the minutest flaw in the pipes, or forcing the water-traps. And though laden with organic poison, — perhaps with the contagion of typhoid or other fever, they may not, — and this is AIR AND HEALTH. 93 dwellings, probably han air in >ur lungs, onic acid, inary air. le oxygen lessened. :ompound lost pemi- e mucous y the skin, ith it fatty ay readily becomes uliar, very ) rendered ooms and trogenous, oxidized, [t is most ; and has , from the the above n, or even constantly air, or in I rendered IS, and all gases and hydrogen, :uliar fetid ;anic com- promotes ) are very ito houses y; passing irater-traps. with the ind this is very important for you to remember, they may not be detected by the sense of smell ; though their pernicious effects may be most serious. The air near marshes and swamps—malaria, contains, among others, the above mentioned gases, as emanating from sewers, etc., with organic effluvia, spores, and many other impuri- ties of this sort. It contains also usually the specific poisons which give rise to ague and remittent fever. These poisons are sometimes carried by winds to distant places, where they produce their pernicious effects. The air from cellars, from being usually confined and deprived of sun light, is frequently very unwholesome. Cellars are frequently badly drained, and, at best, are usually damp, and often contain decaying organic matter, as partly spoiled vege- tables, etc. These are conditions very favorable to the growth of poisonous fungi, spores of which, with the dank, unwholesome air, readily pervade the rooms above, and no doubt give rise to various diseased conditions, of a more or less serious character, in those who dwell there and breathe the air. Humid air from wet, undrained soil interferes with free perspiration and favors the development of rheumatism, con- sumption, and other diseases. As such soil is not favorable to the growth of good crops of grains and fruits, so it is not favorable to the health of man or beast dwelling upon it. Few facts are better established than that drainage of the soil promotes health. The effects of breathing impure air may be both local and general. The local effects involve the lungs and air passages, and are most marked in steel grinders, flax and shoddy workers, millers, potters, and miners, who are very liable to diseases of these structures, — consumption, bronchitis, and asthma. They are caused by the direct mechanical irritation of the parts by the fine particles of steel and other dust produced by these occupations. The general effects involve the entire organism, and from a hygienic point of view, especially in this country, are of much the greater importance. The breathing of air contain- ing decomposed, or probably decomposi«^, excrement itious mat- ters, besides frequently ^^iving rise directly to some of the more specific diseases mentioned further on, produces a condition of the blood and other fluids predisposing the system to these and other diseases of a definite and serious character ; a sort of 'putrid' condition, in short. The poisons pass through the delicate lung tissue into the blood, and though not usually in \v^^ 94 ELEMENTARY HYGIENE. Kufficient quantity i.o speedily overwhelm the organs and func- tions of the body, and produce marked immediaic effects, must necessarily interfere with or prevent healthy vigorous action. The consequences are general lassitude, want of vigor, dyspep- tic symptoms, diarrhoea, headache, and other disagreeable symp- toms, if nothing more serious. Of all causes of death which usually are in action, statistics prove that impurity of air is the most important. Speedily fatal effects from breathing a vitiated atmosphere are familiar enough. It is authentically recorded that the master and mate of a Shetland trading vessel, at Leith, went to sleep at night in the cabin with the companion and skylight shut, and were found the following morning ' almost dead ' from breathing and re-breathing the exhalations from their own bodies. The captain died in 24 hours ; the mate recovered. The captain and mate of a French ship, at Jersey, both died under like cir- cumstances, from the same cause. In 1848, 70 out of 150 pas- sengers died during a stormy night in the tightly closed cabin of the steamer Londonderry, from the same cause. Every one is acquainted with the history of the Calcutta * black-hole,' in which 123 of 146 prisoners died in eleven hours, — poisoned by their own exhalations. Occasionally we hear of a sudden death from breathing the gases of burning coal or illuminating gas. Now, when breathing such poisons in large quantities gives rise to these fatal consequences, it cannot be doubted that breathing them in even very minute quantities is productive of mischief, though we may not be able to appreciate it, or to trace the effects direct to the cause. It is admitted by all i»hysiologists that the re-breathing of matter thrown off by the lungs and skin, produces a * kind of putrescence in the blood ' in proportion to the amount inhaled and the period of exposure to it. Scrofula — consumption being one of its most common forms, is caused by re-breathing breathed air. A celebrated French physician, Baudelocque, writes that, the repeated respira- tion of the same atmosphere is a primary and efficient cause of scrofula j and that invariably it will be found on examination that a truly scrofulous disease is caused by a vitiated air, and it is not always necessary that there should have been a prolonged stay in such an atmosphere. Often, a few hours each day is sufficient; as sleeping in a confined room when the air has not been renewed. Large numbers of the pupils at a school in Norwood, England, some years ago, fell victims to scrofula, and on investigation it and func- Fects, must :)us action, or, dyspep- able symp- I, statistics itmosphere the master to sleep at t shut, and I breathing dies. The he captain er like cir- 3f 150 pas- id cabin of 'ery one is J,' in which :d by their death from ?as Now, 1 gives rise : breathing »f mischief, ; the effects ts that the 1, produces :he amount t common celebrated :ed respira- it cause of ation that a id it is not ged stay in fficient; as 1 renewed. I, England, stigation it AIR AND HEALTH. 95 was decided that insufficient ventilation and the consequent atmospheric impurity was the cause. Twenty years ago con- sumption was very prevalent among the British soldiers. A sanitary commission, consisting of men of the highest standing, after investigation, declared it was caused by over-crowding and deficient ventilation ; — in other words, by re-breathing breathed air. When this cause was removed, — more space in barracks and better ventilation provided — the number of cases of this disease materially diminished. The seeds of contagious diseases— small-pox, scarlet fever, typhoid fever, diphtheria, cholera, measles — may be, and frequently are, communicated from one person to another through the medium of air alone. The contagion particles — the disease germs, from the body — the lungs or skin, of an infected person may pass, as they do in some cases, directly into the air of the room, and be inhaled by another ; or they may be thrown with other excrement into a sewer, or midden, or yard, and sooner or later escape into the air, perhaps into a house, through defective soil pipes or water-closets, and hence into the body of some unsuspecting person ; to work, in either case, their deadly mis- chief These germs are wonderfully tenacious of life ; for living vegetable growths they probably are, germs of the lowest forms of minute plants, which develop, grow, and multiply in the body of the infected person. Abundance of fresh, pure air, containing probably nature's great disinfectant, ozone, seems in some way, probably by oxidation, to render these germs innocuous. Artificial disinfectants may be employed also in rooms to assist in their destruction. Typhoid fever, diphtheria, and cholera are diseases the origin of which is closely connected with collections of fecal and other excrementitious matters. These matters seem to constitute the favorite soil for the development of the germs which give rise to these diseases. Where there is not a free circulation of fresh air, as in sewers and close yards, the germs develop and multiply rapidly, and find their way with the foul air into dwellings, and hence into the bodies of those who inhale the air. The maximum of safety is only secured by having such excrete matters at once destroyed or carried far away from inhabited places. Diarrhoea and other forms of sickness are frequently caused by breathing the foul gases generated in the decom- position of various sorts of filth, and the utmost care should be exercised in reference to this. Of 22 boys at a school at Clap- l!^ 96 ELEMENTARY HVGIENE. ham, England, 20 were seized with violent purging, vomiting, prostration, and fever, within three hours, two of whom died, from inhaling the air from a drain at the back of the house, which drain had been opened two days before, after having been closed for years. Usually, as they were in this case, the effluvia are most offensive to the sense of smell. How to keep the air we breathe pure. — The air may be kept almost perfectly pure around us by free ventilation and constantly removing far away from us all excrete and refuse organic matter — all filth of- every kind and description. There are other means which may be employed, as disinfectants and direct sun- light, but ventilation and the removal of all filth are the two great remedies for foul air ; or, better, the two great means for preventing foulness. The removal of filth, especially from cities and towns, being a matter of public health, we will not discuss the subject of it here further than to state that good sewerage, with abundance of water for flushing or washing the sewers, and a good outfall, — the water carriage system — constitutes probably the best method for removi-^" filth, chiefly because it is almost automatic — self acting. Without these conditions, scavenging or carting away, daily, or onct ..r twice a week, with the use of dry earth or ashes, — the dry j^j/^w— answers, admirably if properly carried out. In this there are few sewer gases clothing to contend with. Every sort of excremental matter and refuse, debility, however, should be taken away in some manner. No slops or washings of any kind must be thrown on the ground near dwell- ings or wells of water. They soon render the soil foul, and it fcoducir becomes a source of poisonous gases. ;nd it is Ventilation — changing the air — is the replacement ot 00m. impure air in a room, or any enclosed space, by pure fresh air current i from without. Want of ventilation is one of the most prolific Ther causes of disease, perhaps the most prolific. It is quite marvel- aising £ mpure s t increai ommen iy takin without endows ufficien ood vei s usuall lous that persons who are very fastidious or squeamish in regard to most matters, will, seemingly without an unpleasant thought,, draw into their lungs, over and over again, air moist and laden with waste excremental matters from their own or another's lungs. People are doing this constantly ; in bed-rooms, in school-rooms, in churches, in shops ; but not in the open air. Hence, chiefly, the great advantage of living much in the open air. When you are in a room of any sort, as at night in your bed-room, contrive in some way to have a supply of fresh outer air reaching you continually. If there is no special means for ventilating, lowerifindow or raise \ glass. 1 head, tO( also, and luxury ; the first Drau draughts and fron strong ci head or ; it is bett to face a ourself even air patients widely o between ifer ve hghtly 01 cool enc They sir reme< resh air vomiting, n died, from ouse, which been closed via are most ) air ma)' be tilation and fuse organic e are other direct sun- ire the two : means for towns, being jct of it here nee of water , — the 7uater for removi"'^ g. Without )nct .-r twice fw— answers, f sewer gases ■ and refuse, No slops or [ near dwell- foul, and it lacement ot ire fresh air nost prolific luite marvel- ih in regard ant thought,, ;t and laden )ther's lungs, chool-rooms, ;nce, chiefly, When you om, contrive eaching you lating, lower AIR AND HEALTH. 97 or raise a window sash ; if you cannot do this, break a plate of glass. If the weather is cold, put on extra clothing, cover your head, too, if you will, but not your face. Use a little extra fuel also, and if necessary, to compensate, deny yourself some common luxury ; deny yourself almost anything rather than pure, fresh air, the first essential of li*e. Draughts of air inspire terror in some persons — even slight draughts ; but this arises chiefly from habitually avoiding them, and from confinement indoors. To sit or lie for some time in a strong current of air might give you a * cold ' — a ' stuffing ' in the head or a sore throat, especia '..y if not accustomed to draughts, and it is better to avoid steady draughts of cool air ; but much better to face a pretty strong, cool draught, especially after habituating yourself to it, gradually, than to ]')reathe air once breathed, or even air with more than a tiace of br*. . hed air in it. Very sick patients in hospitals, well wrapt, are low sometimes laid near widely open windows, just a little ^o one side of a strong current between the window and an oper, ioor or grale. This is called / jper ventilation. Understand, I do r '>t wish you to think too lightly ot cool draughts of air. They aro injurious when they are cool enough to give rise to chilliness, general or only partial. They simply cool the body more rapidl> , and in a draught more clothing or more exercise is demanded. But It is a sign of debility, weakness, of a diseased condition, in short, which should .' remedied, when one is unable to bear a moderate draught of resh air without taking * cold.' But we can ventilate without )roducing draughts appreciable to one in fair health. To this nd it is necessary to have the air diffused as soon as it enters a oom. This may be best and most simply done by directing the current at once against the ceiling. There are various ways of ventilating, from simply aising a window, to elaborate appliances for withdrawing the mpure air and forcing in the fresh. You know if air is warmed, increases in volume and becomes lighter, bulk for bulk, and :ommences to rise, while cooler air flows down to take its place. )y taking advantage of this law, it is possible to ventilate fully without artificial means for forcing the air. In warm weather, indows and doors may be widely opened, and there is usually ufficient motion of the outer air — more or less wind — to secure ood ventilation. In cold weather the air in any occupied room s usually made much warmer than the outer air, and when a nndow is opened, the cold air flows in ; the quantity depending ii 98 ELEMENTARY HYGIENE, on the degree of difiference in temperature between the inner am outer air, as well as on the size of the opening. With a fire in an open grate to withdraw the impure air, am an opening for the pure air to enter, very complete ventilatioi may be secured. A good tn/et may be provided by raising th( f^f-^' lower sash of a window about two inches, and closing the lowei opening, as by fitting in a piece of wood, or in any other way fresh air will then come in between the sashes, and be directe( ^^^^'^} toward the ceiling. In a room without a grate, an ouf/d may b( ~"^^^^ provided by making an opening into a chimney-flue if there ii f"^^^^ one adjacent. Take care to provide in some way that the fresh aii after entering shall not take a too direct course to the outlet, as it may, and not be thoroughly diffused through the room. You can test and follow the currents by means of a small flame, as o a lighted match. The more directly the current strikes the ceil mg, remember, the better it will be diffused The amount of fresh air required, and which should entei inhabited rooms every hour, for each individual occupant, in ordei that the air in the rooms shall be sufficiently pure for the purpose? of health, has been placed by the best authorities at 3,000 cubic " feet. You breathe more than 1,000 times every hour, and aiJ'^S'^^^^ The eetofro perm lead pt na roo hree re or eacl iven in chool r( t be le t is quit The 3pen gn efore it every breath you render unfit for breathing again at least three Even itoves n cubic feet of fresh air. Even with a supply of 3,000 cubic feet "^'^S*"! per head per hour, the air in the rooms would not be quite so \ ^^^^^ pure as ordinary atmospheric air. Indeed it is almost impossible ^^ 5^^ to keep the air in confined inhabited pl.-ces quite as pure as that "^^^ outside. Sick people require more fresh air than those in health, In ordinary conditions of the atmosphere, in moderately cold weather, with the temperature of the air in rooms considerably higher than that outside, air will enter a room through an opening ,. . at an average speed of about five feet per second. With this '^'°S ^^ itmospl The iniform average speed ot about nve leet per velocity, an inlet opening having a sectional area of 24 square *""^='^' inches, — that is, an opening i inch by 24 inches — would permit* ^° * the entrance of 3,000 cubic feet of air per hour. Three in dividuals occupying a room would therefore require an inlet foi fresh air 3 inches by 24 inches. Two or more smaller inlets are better than one large one. Outlet openings for the escape ol the impure air should be fully as large as the inlets, excepting those around which the temperature is increased, as in the case of a chimney warmed by a grate fire ; then the area of outlets may be smaller than that of inlets, as the air would be drawn out more rapidly . warm re and thi warm re giving e ?o° F. ; warmer with thi to wear Grei injure t the inner am mpure air, am 2le ventilatiot by raising th ;ing the lowei ny other way id be direct© outlet may b( liie if there ii at the fresh aii he outlet, asil \ room. Yoi ill flame, as o rikes the ceil \ ;h should ente ipant, in ordei r the purpose at 3,000 cubi hour, and at least thre« 000 cubic feel ot be quite so ost impossible s pure as thai lose in health derately cold considerablj jh an opening d. With this of 24 square -would permit r. Three in^ re an inlet fo iller inlets are the escape ol ets, excepting as in the case rea of outlets be drawn out AIR AND HEALTH. 99 The amount of cubic space — that is, the number of cubic eat of room space — allowed for each individual should be sufficient permit the passage through it of 3,000 cubic feet of air per lead per hour without producing perceptible or disagreeable Iraughts. The larger the cubic space the less frequently will the lir in it require to be changed or replaced with fresh air, and the asier it will be to ventilate it without draughts. If you were in room or closet five feet square on the floor and eight feet high, -having 200 cubic feet of space, the air in it would require to be renewed 15 times every hour, or once every four minutes ; while a room five times as large, — having 1,000 cubic feet of space^ hree renewals every hour would be sufficient. The space allowed or each individual ought not to be less than 1,000 cubic feet, ven in the case of a large room, having many occupants, as ichool rooms, for example ; never, under any circumstances, should be less than 500 cubic feet, for each. With over-crowding, it is quite impossible to keep the air sufficiently pure. The best methods for warming dwellings are, that of the open grate fire in the rooms, and that by which the air is warmed lefore it enters the rooms by means of pipes filled with hot water 3r steam. The objections to warming rooms by means of air tight itoves may be largely overcome by providing ample means for :hanging the air in the rooms, — inlets and outlets, and by never llowing the stove to become very hot. Iron at a high temperature enders the air which comes in contact with it more injurious to )reathe than it otherways would be. A stove of highly polished imooth metal is better for warming air than one of ordinary :ast iron. The temperature of the air in rooms should be kept as miform as possible ; and a thermometer ought to hang in every living room, as a guide. It is debilitating to live in a too warm itmosphere, and the system is thereby rendered more susceptible 10 cold. One takes cold easily who is accustomed to live in a varm room. Besides, as air expands b\ heat, warm air is rarer and thinner than cold air, and contains less oxygen ; and in a warm room therefore you breathe and consume less of this life ;iving element. The air around us should not usually exceed 70° F. ; and if only 60° or 65° it will be better. Some require a ivarmer atmosphere than others, though habit has much to do (vith this. It is not good to sit almost shivering, but it is better wear extra clothing than breathe too warm thin air. Great and sudden changes of temperature are apt to injure the health, more or less, though with due caution they tend ■ lOO ELEMENTARY HYGIENE, to invigorate the skin and system generally. You should never go from a very warm room into the cold air when your body is in the act of cooling. If you are over heated in a warm room, either go out at once, while quite warm, or wait until you have become comfortably cool. And always put on an extra coat or shawl on going out, in such circumstances. If the difference in temperature between the inner and outer air is very considerable it would be safer for you to breathe, for a little time at least after you go out, through a fold or two of a muffler or handkerchief, or persistently through your nostrils, keeping your lips closed, so that the air may be slightly warmed before it reaches your lungs. Disinfectants are substances which destroy, or oxidise and render harmless, or less injurious, decomposing organic matters, offensive or poisonous gases, and the specific contagions of disease, in the air. Substances which simply deodorize, or conceal bad odors, as burnt coffee or rags, or even fragrant substances, as cologne and camphor, are not necessarily disinfectants. Some disinfectants are quite odorless. More or less Ozone, natures great disinfectant, is believed to be always in good pure air. Ozone seems to be a peculiar condensed form of oxygen, which oxidises, or combines with, poisonous organic substances more readily or forcibly than does even ordinary oxygen itself. Hence, many believe that abundance of fresh pure air is the best disinfec- tant. It disperses or scatters foul matters of every sort, and then soon decomposes and destroys them'by oxidation. Ozone, it is said, is developed by fragrant flowers; it may be artificially prepared. Many substances are used for purifying the air in rooms and other limited spaces. Carbolic acid destroys organic impurities and low forms of vegetable and animal life, and prevents putre- faction. Diluted, it is useful for disinfecting privies and water- closets, scrubbing floors and cleansing infected clothing. Fumes of burning sulphur are excellent for disinfecting empty rooms, as after sickness ; the rooms should be closed ; and the furniture may first be removed into the open air, and repolished. Potas- sium permanganate in solution is a good and odorless dis infectant, and may be frequently and freely sprinkled about a sick room with advantage. Ferrous sulphate (copperas), in fine powder or in strong solution, is very useful for disinfecting and deodorizing privy vaults and other collections of filth. Many compounds for disinfecting purposes are in the market, some of which are valuable. Dry heat, if sufficiently great, is destructive of all organic matter, and is probably the best disinfectant for clothing, bedding, and like articles. lould never your body is warm room, itil you have ixtra coat or difference in :onsiderable, ime at least andkerchief, ps closed, so our lungs. oxidise and inic matters, IS of disease, conceal bad abstances, as ants. Some me, natures od pure air. ^ygen, which stances more elf. Hence, best disinfec- ort, and then Dzone, it is illy prepared. I rooms and lie impurities events putre- :s and water- ng. Fumes mpty rooms, the furniture d. Potas- odorless dis- about a sick ras), in fine nfecting and filth. Many •ket, some of s destructive linfectant for AIR AND HEALTH. lOI Sun light may be regarded as a disinfectant. Where it can- not penetrate, the air soon becomes dank and unwholesome. It is no doubt essential to the preservation of the air in a pure state. The direct rays of the sun, indeed, seem necessary to the well being of both plants and animals. Look at the puny, frail plants which grow in shaded places. Statistics show that there is more sickness in shaded dwellings than in those freely exposed to the sun. Dwellings should be well lighted, — provided with abundance of window glass. Especially should sun light be ad- mitted freely into bedrooms. Never fear the sun light, but seek it, even the direct rays of the sun, when the weather is not very warm. When the rays pour down very hot, you should however when exposed to them, especially if you are at play or work, be very careful to keep your head and even your whole body well shaded and protected, as with a broad rimmed and rather high crowned hat, or they may injure you. Respirators, to strain or filter the air and also, sometimes, to slightly warm it, before it enters the lungs, are sometimes worn over the mouth. Many impurities may no doubt be removed from the air by straining it, as through cotton batting. A silk handkerchief worn over the mouth in a malarious district will, it is said, prevent the entrance into the lungs and body of the poison which gives rise to ague. The practice of wearing respirators of this sort habitually, however, is not a good one. The best res- pirator is the nostrils (page 43). These, in most circumstances, are sufificient. They are the natural air passages, and you should accustom yourself to breathe through them constantly, by keep- ing the lips closed. CHAPTER Xni. WATER AS REGARDS HEALTH. Perfectly piire water, entirely free from all foreign matter, is never found in a natural state, and can be obtained only by the most careful distillation. All waters in ordinary use contain some foreign substances, some of which are essential to good water, while others are more or less objectionable, and are regarded as impurities. Good water always contains atmospheric air. with an excess, or extra amount, of oxygen and carbonic acid gas. These give ).H :i I02 ELEMENTARY HYGIENE. to water its agreeable taste and sparkle; without them it is very in- sipid. Boiling drives them off, and hence boiled water is tasteless and flat ; though it soon absorbs air again when exposed to it. Mineral salts, chiefly salts of lime, are also usually found in good ordinary water. Water containing the above substances, and even also traces of some others, and not an excess of lime salts, is called good or pure water ; it is suflicienlly pure for all domestic purposes. It is only when it contains an excess of minerals, or, more especially, organic matter, or lead, that water is regarded as too impure, and dangerous, for domestic purposes. To be good, water should be quite colorless, clear and transparent, and without odor or peculiar taste, and it should not give a deposit of any sort on standing for some time. Water is a most powerful solvent. It quickly takes in gaseous, liquid, or solid substances, when in contact with them. If you drop a lump of white sugar into a glass of good water, in a little time you know all the sugar disappears — dissolves, and you cannot see any trace of it ; its minute particles have been separated and scattered by the solvent power of the water. If you taste any part of the fluid, you know by the taste that it con- tains sugar, particles of sugar are in every drop of it. If you put almost anything into water, if it is not all dissolved, like the sugar, some portion of it is soon extracted and taken in by the water. It is because of its great solvent powers that water is so apt, as it is well known to be, to contain impurities of different sorts. Almost every where on the surface of the earth are more or less dead or- ganic matters, animal and vegetable, usually in a decomposing or putrefying state, and therefore the more readily soluble. Water in flowing over the ground, as after a rain fall, or in picking its way, as it does, through the upper stratas of the soil, comes in contact with these decomposing organic matters, and dissolving and taking up parts of them, thus becomes contaminated and impure. All fresh water is derived from the watery vapor in the at mosphere, which becomes abundant, and is condensed and falls to the earth in the form of rain or snow. When rain falls, a portion of it evaporates into the air again from where it falls ; more of it is used in the processes of growth of vegetables and animals ] a large portion runs off" the surface of the ground, collects in streams, and flows towards the sea; while the remainder filters or strains its way through the soil and reappears in springs and wells. Rain water, in falling through the air, takes down with it and retains a large amount of air, with an excess of oxygen and car- WATER AND HEALTH. 103 t is very in- is tasteless osed to it. nd in good tances, and lime salts, ill domestic linerals, or, regarded as o be good, ind without •sit of any kly takes in with them. )d water, in isolves, and have been water. If that it '.on- If you put :e the sugar, water. It is apt, as it is ts. Almost ess dead or- )mposing or ble. Water picking its 1, comes in I dissolving linated and or in the at 1 and falls to Is, a portion more of it is lals ; a large in streams, or strains its Us. 1 with it and gen and car- bonic acid gas, besides ammonia, organic matter, and any other impurities which the atmosphere may contain. The air, oxygen, and carbonic acid, make the water much more palatable as a drink. The peculiar * soft ' feel of rain water, as distinguishing it from ' hard ' water, is in part due to the absence of lime salts, afterward acquired in the soil, and in part to the ammonia de- rived from the air. The first portion of a rain fall, especially if collected from roofs of buildings, is always impure, from contain- ing organic matters of various sorts, washed from the air and the roofs. But when collected after rain has been falling for a short time and purified the air, and especially if collected in the open country, rain water is the purest of all natural waters. It is a much more powerful solvent than hard water, and in cooking, when the object is to soften the texture of substances, animal or vegetable, or to extract their valuable parts, as in preparing broths, tea, and coffee, it is much superior to hard. It is believed by many to be less objectionable as a beverage than water containing lime and other salts. Spring and well waters hold in solution more or less mineral or saline matters, derived from the soil ; and their quality and com- position depend largely on the nature of the soil through which they have passed. The mineral salts confer upon water its condition called hardness, and cause it to decompose or curdle soap. In pass- ing through the soil, rainwater undergoes two important changes: it loses organic matter which it had acquired in the air or on the sur- face of the earth ; and it dissolves, and retains in solution, inor- ganic or mineral matter from the soil. On the one hand, the earth acts as a filter, and gradually strains out, and the oxygen of the air in the soil oxidises, the organic impurities ; hence deep well waters, which have trickled through much soil, are usually most free from organic matter. On the other hand, in trickling through the soil, water acquires a still larger amount of carbonic acid gas from the air in the soil — which is rich in this gas— and while this makes the water more sparkling, it greatly increases the solvent powers of the water upon mineral matters. This is proved by boiling hard water. The heat expels the gas, and the lime and other salts previously held in solution are set free, and settle and form crusts on the sides and bottom of the vessel in which the water has been boiled. You will find crusts of metallic salts, formed in this way, in most tea-kettles. These waters there- fore vary with the amount of carbonic acid and lime and other minerals in the soil. 7 I04 ELEMENTARY HYGIENE. River and lake waters receive the washings of the sur- rounding districts, and hence they sometimes hold in solution considerable impure, organic matter. They contain less mineral matter, and are therefore softer, than spring and well waters. In large bodies of water, as in the air, natural processes go on which tend to purify the water : many of the impurities are oxidised, and thus rendered harmless, by the free oxygen in the water. The constant movement of river water favors the oxidation. The presence of growing plants, too, in water, aids in the purifying process. Impure water has long been regarded as a common cause of disease ; and within the last few years, close investigation has shown conclusively that a large amount of disease and many deaths are caused by it. Water may be rendered impure by ex- cess of mineral matter, as lime and other salts, or by vegetable and animal matter. Mineral impurities in water, with the excep- tion of salts of lead, have not been shown to have given rise to much positive injury to the health. When in large quantities, they are apt to cause dyspeptic symptoms ' nd other disorders of the alimentary canal. It is the organic, fiequently excremental, matters, in a state of decomposition, with, sometimes, contagion particles of specific disease, which cause the great mischief. Some- times water, seemingly pure to the senses, contains minute living organisms, which cannot usually be seen without a microscope, and such water should never be used for drinking purposes. Water contaminated with lead, as from leaden pipes, fre- quently produces symptoms of lead-poisoning. When water con- taining oxygen and carbonic acid is in contact with lead, a salt of the metal is formed which readily dissolves in the water. A high authority, Dr. Stille, tells us that poisoning by water contaminated with lead, is probably of more frequent occurrence than is gener- ally supposed, for in some of the most deplorable instances of it, the real cause of the mischief remained unsuspected for a long time. He says it often acts secretly and insidiously, as I have told you other causes of disease do, and that it undermines health and even destroys life without a suspicion existing of the real cause. When the use of water from a leaden pipe is unavoidable, as it too frequently is, the risk may be greatly lessened by reject- ing the first portions drawn off — that which has been standing in the pipe ; and this should invariably be done. The organic impurities in water have numerous sources, f the sur- solution ss mineral aters. In on which dised, and ■ter. The ion. The purifying n cause of yaiion has ^nd many )ure by ex- ' vegetable the excep- ven rise to quantities, isorders of xremental, contagion lief. Some- nute living nicroscope, OSes. I pipes, fre- water con- id, a salt of ;r. A high ntaminated in is gener- inces of it, for a long as I have lines health of the real navoidable, i by reject- standing in )us sources, WATER AND HEALTH. I OS but for the most part, they are furnished, like the impurities in the air, by the habitations and trades of men. The washings, after a rainfall, from all collections of filth, in back yards, barn-yards, or elsewhere, from cess-pools, piggeries, slaughter-houses, and cer- tain manufactories, find their way into wells and other sources of water-supply, often through porous soil, or perhaps soil previously saturated with impurities. It is very important, too, to bear in mind that water will sometimes carry org^anic impurities a long distance through the ground. It has been known to carry the specific poison of typhoid fever nearly a mile in this way. The presence of putrescent animal matter converts drinking water into a dangerous poison. A trace of faecal matter, when under the process of active change or decomposition, in a well of water, may so poison the water that it becomes the means of prostrating with sickness an entire family, or all who use the water. The principal diseases which it is well known have been directly caused by the use of water containing organic impurities of different sorts are, typhoid fever, cholera, diarrhoea, and dysen- tary ; while the specific contagions of other diseases, as diphtheria and erysipelas, are in all probability sometimes carried by water from one individual to another. Besides giving rise in this way to these diseases, the use of such water, like the breathing of foul air, gradually induces an impure condition of the blood and other bodily fluids, causing general unhealthfulness, debility, and a pre- disposition or tendency to colds, inflammations, and other diseases. How shall we know when water is pure enough for drinking and domestic purposes ? We can only know this posi- tively after the water has been examined by a practical chemist. The source and history of the water should be learned, however, and this will assist us in judging of its purity. If taken from a deep well, situated a safe distance from any putrefying organic matter, and so constructed that surface washings cannot get into it, and the water is perfectly clear and without smell or disagreea- ble taste, it is most likely good. Water giving a bad smell or bad taste should always be rejected. Water for examination should be put in a glass vessel, but the vessel must first be carefully cleaned, and then rinsed two or three times with some of the water to be examined. Hold a portion of the suspected water in a clear glass bottle before a good light to see if it is perfectly clear and transparent, as good water should be. Lay the bottle on white paper to ascertain the color or tint I ' T 1 06 ELEMENTARY HYGIENE. of the water. Organic matter in water usually gives a yellow, green, or blue tinge ; though the same may be given by mineral substances. Peat and clay give water a brownish tinge. If you put a little water in a wide-mouthed flask and shake it well, and an unpleasant odor is emitted, the water is unfit to drink. If no odor, warm the water by heating the flask, and add a little caustic potash ; if a disagreeable odor is now given out, the presence of considerable organic impurities is indicated. Get a little nitric acid and some nitrate of silver in solution, from a druggist, slightly acidulate some of the suspected water with the acid, and add a little of the silver solution ; if the water now becomes decidedly turbid or riled, it is probably contaminated with sewage or such like impurities. Water may be purified in various ways, but the most practical methods are those of boiling and filtration. The addi- tion of some chemical substances, as alum or permanganate of potash, helps to purify water, but this means of purification is not to be relied upon. Boiling destroys all vegetable and animal organisms in water, and probably the specific contagions of dis- ease ; it drives off gases of all sorts, and sets free or separates lime salts, which adhere to the vessel. After boiling, water should stand off the fire for a short time before being used, in order that lime salts or any other suspended matters may settle tc the bot- tom of the vessel and be rejected. By straining or filtering water through certain substances many impurities, organic and mineral, are removed. The best filtering substances are animal charcoal and magnetic carbide of iron. Ordinary vegetable char- coal and sand are often used. Whatever material is used it soon loses in a measure its purifying properties, and requires to be ex- posed for a time to the sun and air, or to be renewed. If this is neglected the water may eventually pass through the filter with but little change. All wells should not only be securely covered, but the upper few yards of their walls should be made as impervious to water as possible, in order to prf.vent the entrance of surface water. The greatest care must be observed in locating, as well as in construct- ing, a well. It must be a safe distance, and the further the better, from any cess-pool, piggery, stable, or refuse matter; and the walls should be carrieii up a foot or more above the level of the surrounding surface of the ground. It is never safe to use water from wells in cities and towns, where there are sewers, and where WATER AND HEALTH. 107 5 a yellow, by mineral e. If you t well, and nk. If no ttle caustic )resence of little nitric ;ist, slightly and add a 5 decidedly ge or such t the most The addi- mganate of ation is not and animal ions of dis- parates lime ater should 1 order that tc the bot- filtering )rganic and are animal etable char- ised it soon es to be ex- If this is filter with It the upper to water as n'ater. The n construct- r the better, r; and the level of the to use water and where the dwellings and outhouses are near to each other, and the yards small. With such conditions and surroundings it is almost impos- sible to prevent the contamination of well water. Wells at best should be occasionally inspected, and thoroughly cleaned when necessary. Cisterns which receive rain-water should be well cleaned once or twice a year, at least. Both wells and cisterns should in all cases be ventilated. This may be done by having a tube, or better, two tubes, three or four inches in diameter, com- municating with the well through the cover, and extending up- wards a yard or two above the top of it, and through which air may pass in and out of the well. The tubes should be kept cov- ered with wire gauze. Water as a beverage, for allaying thirst, is probably supe- rior, under most circumstances, to all other liquids. Natural thirst is a desire for some diluting fluid, and the more perfect and sim- ple this is, the better. Acidulated drinks, as the juices of fruits, are often useful, and sometimes seem to allay the thirst more com- pletely than water. Persons in good health, who eat only whole- some, not highly seasoned food, and masticate this well, usually have but little thirst or desire for liquids. Water about lilood or new milk-warm, sweetened, m akes a palatable drink for many who have not been accustomed t o * stronger ' drinks. The addition of milk improves it. It is a pity that so large a number of com- pound, artificial drinks have been brought into popular and gen- eral use. When over-heated by exercise, one should not drink much cold water, though it may quite safely be sipped slowly at any time. CHAPTER XIV. FOOD AS REGARDS HEALTH. The purpose of food is to supply material for the growth and repair of the bodily tissues, and fuel for generating heat and force. It is evident therefore that foods must contain the elements out of which the tissues are formed and substances which may be readily oxidised or burned. And foods must be of such a nature as to be capable of solution or digestion in the alimentary canal, so that they may be emptied into the circulating blood. There are four groups into which the whole of our food-stuffs io8 ELEMENTARY HYGIENE. I. may be divided, as stated in the chapter on digestion (page 75). These are proteids, fats, amyloids, and minerals. The first three are organic foods. The proteids contain nitrogen and are flesh or tissue forming substances. Fats and amyloids — the latter con- sisting chiefly of the starches and sugars — contain no nitrogen, and are, for the most part, used as fuel — for burning. Starch you will remember is converted into sugar in the alimentary canal. There are, then, the amyloids or nitrogenous foods ; the fats, and sugars or starches, which are non-nitrogenous ; and the minerals. This classification relates rather to the nourishing prin- ciples of foods. Most of our articles of food contain two or three of these principles, and many foods contain all four ; but not any one of them in the proportion to constitute it alone a perfect food for constant use. Bread contains the four, but only a very minute quantity of fat ; hence it is usually eaten with butter. Flesh con- sists chiefly of proteid matter, and is eaten with bread — which, though containing considerable proteid matter, too, consists largely of starch — or with potatoes, which are nearly all starch. Milk is the most perfect food, but it does not contain sufficient of the amyloid principle (sugar) for adults. The proteids then all contain from fifteen to sixteen per cent, of nitrogen. The nutrient compounds, albumen, fibrine, caseine, gelatine (page 10), syntonin, gluten, and legumin, with most of which you must be already familiar, contain nitrogen, in about this proportion, and they are all proteid substances. Foods which contain one or more of these are called nitrogenous foods or pro- teids. The most common and abundant of these substances is called albumen. It is a transparent, glairy fluid, which becomes solid on being heated. White of egg is nearly pure albumen, and you know how readily it becomes solid or hard when placed in boiling water ; it gets solid in fact before it gets as hot as boiling water. It is found in large quantities in all animal fluids, and also, or something very like it, but to a less extf'nt, in the juices and seeds of plants. Fibrine, you will remember, is the stringy substance which gives rise to the clot in blood (page 52). A somewhat modified form of it, seemingly, called muscle fibrine, or syntonin, is the chief constituent of flesh. Gluten, or vegetable fibrine, is the tough, stringy principle of grains, and is most abundant in wheat. If you chew a few grains of wheat for a few minutes you obtain some of it, as a grayish, tough mass, while the other constit- h FOOD AND HF.ALTH. 109 (page 75)- first three d are flesh latter con- nitrogen, Starch alimentary foods ; the and the shing prin- vo or three )ut not any lerfect food ery minute Flesh con- id — which, lists largely 1. Milk is ient of the n per cent, ne, caseine, th most of n, in about bods which )ods or pro- :es is called comes solid ;n, and you d in boiling iling water, ind also, or s and seeds y substance i somewhat - syntonin, le fibrine, is ibundant in ciinutes you ther constit- uents of the grain, chiefly starch, seem to dissolve in your mouth. It is the gluten which makes dough tough and stringy, and which retains the gases, generated in the dough by the yeast ; and thus the bread becomes porous or spongy. Caseine is the curdy principle which forms in milk when this is heated with an acid, and is the chief constituent of cheese. Legumin, or vegetable caseine, exists in large quantities in peas and beans. The jelly- like principle of animal jellies is called gelatine. It is obtained chiefly from bones and the tissues of joints. All these substances except gelatine are very like each other in composition, and may to a great extent replace each other in nu- trition. Though they differ in appearance and physical proper- ties, as in their behaviour with heat, etc., they serve a common purpose in the organism. Whatever other purpose they serve, they furnish material for the formation, growth, and renewal of the tissues. Every structure in your body in which any form of force is manifested — nerves, muscles, cells — is nitrogenous. And hence, though heat, force, and mechanical motion in the body are owing to the oxidation or burning of fat or sugar, or of nitrogen- ous foods, all manifestation or show and direction of force and motion must be given by the nitrogenous structures. The fats and amyloids contain no nitrogen, and they are the most important constituents in giving rise to heat. All fats have a great similarity of composition, and are found in abundance in both plants and animals, often in the form of oil. The amyloids — sugars, starches, and gums — are principally vegetable products, and enter largely into our ordinary foods. Sugar is obtained from the sap, fruits, and seeds of various plants. Sago, arrow-root, and tapioca are chiefly starch. Potatoes and rice, too, are mostly starch. The mineral constituents of foods are water and various inor- ganic salts, as common table salt, and salts of lime, potash, soda, etc. All these except common salt are furnished in sufficient quantities as constituents of the various foods. A well mixed diet, containing a proper proportion of food from each one of the four groups of almients is very essential to health. If you were to confine yourself for any lengthened period of time to any one group, you would get sick. True, the proteids contain elements for burning — carbon and hydrogen — as well as nitrogen, and you could live on them the longest, even for a long time; but it would not be economical to do so, neither as regards [If i- no ELEMENTARY HYGIENE. the foods consumed nor your bodily functions. Because, in order to get from the proteids — as bread and flesh — sufficient carbon and hydrogen for burning in your body, you would have to consume and digest more nitrogen than you would require ; and certain organs, notably the kidneys, would be overtaxed in getting rid of it. Hydrocarbons then — fats and amyloids — are essential to health. But it seems, furthermore, that these two non-nitrogenous foods will not entirely replace each other, and that both are neces- .sary. Fats are best for the purposes of combustion, and a certain amount of fatty food seems indispensable to health. It has been observed that people who do not eat a moderate quantity of fat are not well nourished, and are disposed to consumption, a veiy fatal disease. Finally, the desire for starch and sugar is almost universal ; and in no case in which it can be obtained is starch, in some form — as potatoes, rice, bread — omitted from the diet. What proportion of each group of foods is necessary ? This it is not easy to estimate and determine precisely, and to apply the estimation to ordinary foods, and to individuals in all circumstances. You should study carefully your own natural ap- petite and desire, in compliance with rules laid down in future pages, while the study of the following table may assist in guiding you. It has been compiled partly from observation on a great number of persons and dietaries, and partly from physiological experiment : Water-free substances, per day. Moderate work. Ounces avoir. Very hard work. Ounces avoir. Rest, without work. Ounces avoir. Proteids Fats 4.6 2.95 H-25 I. 6 to 7 3-5 to 4-5 16 to 18 1.2 to 1.5 2.5 I. Amyloids 12. Minerals •5 Total 22.80 26.7 to 31.0 16.0 Man is omnivorous, — that is, he eats all sorts of foods : and because he habitually eats such a variety of foods he is the more li.ible to errors in diet. If you were to subsist wholly on a few simple articles of food you would be less likely to eat improper substances, or to eat too much, as many do. Variety in foods contributes to man's pleasures, but it demands greater care and study in regard to his diet. What you have now learned about foods relates to their various c, in order arbon and ) consume id certain ting rid of sential to itrogenous are neces- i a certain t has been itity of fat on, a veiy is almost 1 is starch, the diet. necessary ? ely, and to luals in all latural ap- i in future in guiding 3n a great lysiological ithoiit work. ;es avoir. !.S >.o foods : and s the more • on a few t improper ty in foods r care and leir various FOOD AND IIKALTH. Ill nutrient principles, and to the relations of these to digestion and to the requirements of your body. You must next learn some- thing about the various food-stufifs as you find them, at the butch- ers, the bakers, the fruiterers, and the grocers. It will be most convenient for you to study them under the following heads : — animal foods, vegetable foods, liquid fooc's or drinks, and condi- ments or seasoning agents. Animal foods include flesh, and other parts of the bodies of animals, eggs, milk, butter, and cheese. The flesh of the various animals is almost exactly the same in constitution, and contains a large amount of nitrogenous matter in a concentrated form, and easy of digestion, when properly cooked. It is mixed with more or less fat, and contains some essential salts. The quality of flesh depends very much on the manner in which the animals had been fed. The best is from animals fattened on fresh pasture, with a I t:le grain. This method of feeding secures the most healthy and ocst developed animals, with better diffusion of fat through the flesh than stall-feeding. Animals fattened on the refuse of distil- leries, breweries, and slaughter-houses, or on decaying or dis- eased food, as musty or mouldy grain, are not fit for food. The flesh of good beef, mutton, or pork, is of a light red, approach- ing a scarlet hue, firm to the touch, not sodden or moist, and not easily torn across the fibres. Pale, moist flesh marks that of a very young animal ; and very dark, red flesh, that of the old tough one, or one that had been diseased. Flesh should be entirely free from disagreeable odor or marbled spots. It should not be too fat, and the fat should be firm and white, or but very slightly tinged with yellow, and free from bloody points. Bad flesh is usually flabby or sodden or mottled, the fat dirty looking, and the smell unpleasant. Pork, though highly nutritious, is not so diges- tible as beef or mutton, being closer in texture, and usually con- taining much more fat. It is not well suited for those not engaged in active or laborious work. Flesh of most poultry and fish is lighter in color, less juicy, and contains less fat, than butchers' meat. The flesh of crabs and lobsters is difficult of digestion. The heart and tongue are muscular organs, and very nutritious, but being denser in texture, are not so easily digested as other flesh. The parts about joints are used to make soups, which are nutritious and, when properly prepared, easily digested. The glandular organs, as the liver and kidneys, are nutritious, but rather difficult of digestion. Tripe, on account of containing some digestive juices, is readily dissolved in the stomach. ^np 112 ELEMENTARY HYGIENE. All salted and cured meats are less nutritious and more in- digestible and unwholesome than fresh meats. The salt hardens the fibres and extracts the juices of flesh. Eggs consist chiefly of albumen (the white) and fatty matter (the yolk), with considerable salts, especially those containing sul- phur and phosphorus. They are a highly concentrated food, and when fresh and properly cooked they usually agree with the healthy stomach and digest readily. Like flesh, they contain no starch or sugar, a'ld should be eaten with starchy foods, when they form an excellent article of diet. Eggs of the barn-door fowl are prefer- rable to those of the water fowl. The food of the fowls greatly in- fluences the flavor and goodness of the eggs. Eggs should be cooked only by boiling, or better, in water not quite boiling, and to only thicken or ' set ' the white, leaving the yolk soft. Raw eggs after thorough 'whipping', to a froth, are easily digested. Milk contains all the constituents necessary for complete nutri- tion, and approaches nearer to a perfect food than any other article of diet. It is in fact a perfect food for the young ; but in active adult life it must be combined with more solid or starchy foods. No two cows give milk exactly alike in composition, and the milk of the same cow will vary much with the food she gets. The food affects the milk perhaps more than it affects the flesh, and milch cows should never be fed on refuse or bad food of any kind. A hundred parts of good, average cow's milk contains about 13 parts of solid matter, as follows: 4^ parts of caseine ; 4}^ of milk sugar; 3^ of fat or butter, and the remainder of salts. It should yield from 7 to 12 per cent., by volume, of cream. The milk of goats is richer in solids. Human milk contains only about one-third as much caseine as cow's milk, but a little more butter, and nearly 50 per cent, more sugar. Good, pure milk is almost perfectly white, opaque, not at all sticky or stringy, free from any disagreeable smell or taste, and without sediment of any kind on standing. When not up to this standard it should be rejected. Milk from very old, badly fed, or, especially, diseased cows should never be used. Milk is peculiarly disposed to absorb foul odors and such like impurities, and never should stand for a moment near any such. It should be kept in a clean place, and nearly at a freezing point if possible. Milk is a wholesome and valuable ar- ticle of diet, agreeing best with some persons after it has been boiled. But you must remember that it is much more than a dri]ik, and you should never use it simply as a drink, as it too ind more in- salt hardens fatty matter )ntaining sul- ed food, and h the healthy I no starch or they form an f\ are prefer- Is greatly in- ;s should be oiling, and to Raw eggs ted. mplete nutri- other article but in active y foods. No the milk of The food 1, and milch ny kind. A Dout 13 parts f milk sugar; should yield [k of goats is one- third as nd nearly 50 rfectly white, disagreeable on standing. Milk from lid never be DTs and such loment near I nearly at a valuable ar- it has been nore than a ik, as it too FO>"»D AND HEALTH. "3 frequently is used, when food is not needed, as after a full meal. It contains half as much solid matter as flesh and more than some solid vegetable foods. Butter, the almost indispensable addition to bread, is the fatty part of the milk, united or ' gathered ' into a mass by churning, with a little of the caseine of the milk. Good butter when melted yields a clear oil, with but little sediment. It is an easily digested fat, and is said to favor the digestion of those foods which are de- ficient in fat, when it is eaten with them. The less caseine butter contains the more digestible it is, and the better it will keep. As little milk as possible should be churned with the cream, and the milk should be well ' worked ' out of the butter. Rancid or strong smelling butter is more or less decomposed and should never be eaten. Butter, and all fats, when melted at a heat much above that of the blood (100° F.) undergo change,and become more difficult to digest. Hence pastry, and even toast buttered when very hot, are not wholesome. Cheese consists of the caseine (curd), fat (butter), and con- siderable of the sugar, of the milk. Hence it is very nutritious. Being a highly concentrated food it should not be eaten alone, but always with more bulky vegetable foods, such as bread. When good and fresh, and eaten in this v/ay, cheese digests readily enough, though it is more suited to those engaged in the more active bodily occupations. The peculiar flavor of old cheese is owing to com- mencing decomposition, to which the caseine is liable ; it is then more indigestible, and should be eaten only sparingly. When heated, as in toasting, cheese becomes tough, and is then highly rebellious in the stomach. Of vegetable foods, a much greater variety is used than of animal foods. We may consider them all under the following heads : bread producing or cereal grains, « fruits, and succulent vegetable?. Of bread producing grains, wheat, both as regards the nourishment it contains, and the ease with which it is digested is the most valuable. It approaches nearer to a perfect food than any other vegetable product, being next to milk in this respect. Wheat will sustain life longer than any other food except milk. It con- tains more solid matter than any other article of diet ; the propor- tion of water averages only about 10 or 12 per cent. It contains about 12 percent, of gluten, and 70 per cent, of starch, a small pro- portion of fat and sugar, and some important phosphates and other 114 ELEMENTARY HYGIENE. salts. The most valuable parts, the gluten and phosphates, are immediately beneath the skin, and a considerable portion of them is lost, with the bran, in the usual process of making fine flour. Wheaten meal, or unbolted flour — which contains the bran, ground fine — and cracked wheat are therefore more valuable foods than fine white flour, and usually more digestible. Wheaten flour should be free from lumps, or the lumps should break down with the slightest pressure. It should be free from grittiness, as grittiness indicates a change in the starch grains. After being compressed in the hand, good flour adheres in a lump and retains the prints of the fingers longer than inferior flour ; and if cast against a wall a portion should adhere firmly to the wall. Dough made with good flour may be rolled into thinner sheets and drawn into longer strips than that made with inferior flour. Though flour that has been ground for some length of time is usually preferred to that wl* .ch is quite fresh, old flour is less sweet and nutritious than that which is ^wer. Flour is sometimes contaminated with minute living ai... "1 or vegetable growths — insects or fungi. Of the other grains, the oat is nearest to wheat in nutritive value, though barley and rye are but little less nutritious. No one of these gives a flour from which good bread can be made, chiefly because they contain too little gluten. Indian corn contains a large proportion of starch and fat, but much less nitrogen than wheat. Buckwheat is rich in starch, but poor in nitrogen and fat. Rice alsc abounds in starch, but contains little nitrogen, fat, or salts. It is easily digested, and is said to be more extensively cultivated than wheat. Many millions of people subsist almost entirely upon it. Peas and beans belong to a different group, called leguminous, and are very rich in nitrogenous matter ; containing from 20 to 30 per cent, of vegetable caseine, oxlegumin. They are therefore highly nutritious ; though they ore rather deficient in phosphates. They are not so easily digested as wheat. Fruits contain but little nitrogenous matter, with a large amount of water, more or less sugar, and some potash, lime, and soda, in combination with vegetable acids. They all contain a gelatinous substance (pectine), which is the basis of the various fruit jellies. Fruits are valued chiefly for the salts they contain, and for their cooling properties during the warm season. When fully ripe, sound, and eaten in moderation, with more con- osphates, are rtion of them ig fine flour, bran, ground ; foods than r the lumps lould be free starch grains, adheres in a :han inferior idhere firmly e rolled into t made with ■ some length :sh, old flour 2r. Flour is or vegetable in nutritive ritious. No :an be made, dian corn much less but poor in )ut contains nd is said to millions of leguminous, from 20 to ire therefore phosphates. rith a large lime, and 1 contain a the various ley contain, on. When more con- FOOD AND HEALTH. "5 centrated foods, as bread and milk, fruits form valuable and wholesome foods, easy of digestion. The grape, when sweet, is regarded as one of the most valuable, safe and nutritious. The strawberry and raspberry are very safe fruits ; and so are the better varieties of the apple, pear, and peach. The cherry and plum are less so. Of imported fruits, the orange, pine- apple, and date are wholesome and digestible. The tomato, though highly prized by many, contains very little nutriment, and is less digestible than some other fruits. Melons and such like fruits are rather difficult of digestion and liable to disturb the stomach. All fruits should be well masticated when eaten, and the seeds and usually the skins should be rejected. Unripe fruits contain much less sugar and more water than ripe fruits. They are for the most part very indigestible and you should never eat them. Of the succulent vegetables, the potato is the most im- portant and the most extensively used, coming next to grains in nutritive value. It contains about twenty-six per cent, of solid matter, nearly all starch ; and hence it is habitually eaten with flesh meats. Potatoes which boil dry and mealy are much easier of digestion than those which are hard and waxy when boiled. The turnip, parsnip, carrot, and beet contain much less solid matter than the potato, but more sugar. They contain a volatile oil, which contributes to their flavor, and they are used chiefly as a relish. They are not so digestible and universally acceptable to the stomach as the potato. Asparagus, cauliflower, cabbage, and the onion contain somewhat more nitrogenous matter, and when properly prepared, are usually more acceptable to the stomach. The onion contains a large amount of an in- digestible, volatile oil ; which is mostly expelled however by long boiling, which onions require. Celery and lettuce, when well cultivated and crisp, are usually digestible and wholesome, when taken in moderation, as a relish. The radish is less so. Liquid foods and drinks are upon the whol^^ less digestible than solid foods. The digestive juices are probably poured out less freely when liquid foods are taken, and the dissolving powers of the juices are lessened by the presence of too much fluid. Such foods are not masticated nor insalivated, and when used habitually, except in very moderate quantities, as a few spoonfuls of soup, are relaxing and debilitating to the system. As a rule, in health, liquids should only be taken habitually to allay thirst. ii6 ELEMENTARY HYGIENE. \ ! I Those who eat slowly and moderately of wholesome foods have usually but little thirst, and require but little drink during meals ; and the less taken then the better. The fresh juices of fruits, next to pure water, are perhaps the most natural and least object- tionable drinks. They contain most of the valuable parts of the fruit. They soon undergo change — fermentation, however, and alcohol is formed in them, from the sugar, when they become alcoholic beverages. In this condition they may be more properly regarded as medicines than as foods or drinks. Tea and coffee seem to be almost indispensable drinks in the present state of society ; though in a strictly hygienic point of view society would be better without them, as they are luxuries not at all essential to health. They contain a large amount of astringent matter (tannic acid), which can hardly fail to act injuriously upon the tissues, especially the mucous membrane of the alimentary canal. Their injurious effects are increased by the use of inferior and adult- erated articles, and by the too free use of them, pure or otherwise. Commercial tea consists of the leaves of an evergreen shrub, and its active principle, for which it is most prized, is a vegetable alkali, called theine. This is dissolved by water only at the boiling temperature ; but the peculiar flavor of tea is owing to a volatile oil, which is expelled and lost by boiling. Bright green teas are usually adulterated or * faced * with coloring matters. The pure article has a dull, faded green appearance ; the leaves varying somewhat in color, and also in size. The best teas are said to contain portions of the stalk and flower, and the leaves are not much broken. Coffee is the seed of an evergreen shrub, and contains a volatile oil, and a vegetable alkali, its active principle, called caffeine. The best coffee comes from Mocha; while that from Java is also good. Ground coffee is frequently adulterated with chicory, carrots, peas, etc., when it is more likely to oppress the stomach. The value of tea and coffee depends largely upon their age and manner of preservation and preparation. Tea should be kept in tightly closed vessels. Coffee keeps best in the green state. Chocolate and cocoa are also dispensable luxuries, consist- ing principally of the seeds of a small tree (the cacao). Chocolate is the ground seeds mixed with sugar and cinnamon, and contains a large amount of volatile oil. It is rather difficult of digestion, and not suitable for a weak stomach. Cocoa is prepared differ- ently, and contains less oil and is more easily digested. The FOOD AND HEALTH. 117 ; foods have iring meals; s of fruits, least object- parts of the owever, and hey become ore properly drinks in the >oint of view ies not at all )f astringent usly upon the intary canal, or and adult- Dr otherwise. 1 shrub, and a vegetable t the boiling to a volatile een teas are The pure Lves varying are said to aves are not shrub, and ve principle, • while that adulterated y to oppress argely upon ation. Tea best in the ries, consist- . Chocolate md contains f digestion, Dared differ- ested. The beverages are usually prepared with milk, and in this way they are very nutritious, but not well adapted for invalids. Condiments or seasoning agents.— Under this head may be noticed those substances which are taken with foods to im- prove their flavor. Some of them, as sugar and salt (in some form), are indispensable to the organism ; while others, as the spices, are not essential to health. Sugar is a respiratory food, and is objectionable only when taken in large quantities. While the practice of eating candies and confectionary prepared from sugar is a bad one, and a common cause of disordered digestion and debility in children, the desire for sugar, so universal in children, should be moderately indulged. Preserves — fruits cooked and preserved in sugar — as commonly prepared, are for the most part indigestible. Fruits are more digestible when only cooked for a short time, with a little sugar, and ' canned,' in air- tight vessels. Salt is one of the essentials of life, but it is easy to take more of it than is necessary or wholesome. In modera- tion, especially in connection with vegetable foods, it aids digestion and contributes to nutrition. Vinegar, pickles, and the various sauces, are substances you should avoid if you desire to preserve your digestive organs in good condition. Spices — pepper, ginger, etc., may assist digestion for a time, but the continued use of them, except in very minute quantities, eventually produces debility of the digestive organs, and you should not habituate yourself to foods more than very moderately seasoned with these. About Cooking Foods. — The purpose of cookery is to render foods more digestible and at the same time to develop their flavor. Bad cookery is a common cause of disease, es- pecially of indigestion and dyspepsia, while it is destructive of the nutrient properties of foods, and is therefore a cause of waste. As mankind use such a great variety of prepared foods, the art of cookery is one of much importance, and should receive more attention than it does. It often happens that foods which, when taken alone, are digestible and wholesome, are mixed and cooked together and thereby rendered indigestible and irritating to the stomach, and also less nutritious. Many puddings, most pastry, and, especially, rich cake, are unwholesome and innutritious, chiefly on account of containing so many ingredients cooked together. Two important points to bear in mind in preparing and cooking foods are the following : First, to avoid the mixing and 1 ^ ii8 ELEMENTARY HYGIENE. I cooking together of a number of foodstuffs ; and, se-^ond, to see that the heat employed in cooking is applied properly, for the most part, moderately and regularly. By boiling, meat is rendered easy of digestion, but from one- fifth to one-third of its nutrient matter is removed by the water. To prevent this loss as far as possible the cuts should be large, and they should be placed in boiling water : at this temperature the albumen near the surface of the pieces is quickly hardened, and the escape of the juices is thus greatly impeded. After a few minutes' boiling, the temperature of the water should be lowered to about 170 degrees (F.), or to a point considerably below boiling, and be retained at this temperature until the meat is sufficiently cooked ; that is, until it is made tender and the fibres are easily separated. When the cooking is continued at a temperature above 170 degrees, the fibres shrink and become hard and more difficult of digestion. In making broths and SOups. when the object is to draw out the juices, the meat should be cut smaller and placed in cold water — soft water being best, the temperature of which should then be gradually raised to about 100 degrees. With this degree of heat the albumen is not coagulated, and the largest proportion of nutriment is extracted. After two or three hours of this slow cooking, a few minutes of rapid boiling will com- plete the process. Vegetables require to be boiled until they are thoroughly softened, when they must be removed at once from the water, or they lose a part of their nutrient matter, and become water soaked; this is especially the case with potatoes. Green corn, peas, and beans are better cooked slowly. Hard water withdraws less of the nutrient properties of vegetables than soft water. The process of roasting is perhaps the best for cooking meats, as it retains most of their juices and best develops their flavor. Though the meats lose about a third of their weight, this is chiefly owing to the evaporation of water and the melting of fat. Roast meats are therefore more nutritious than boiled. The process should be commenced with a high temperature, in order to form a sort of crust of hardened albumen on the surface of the cut, which will pre- vent the loss of much nutrient matter. But the temperature must soon be lowered, and the cooking completed slowly, as in boiling. In the process of broiling, the effect on the flesh is much the same as in that of roasting. It should be conducted with a high temper- ature at first, and afterward with a lower. In stewing, the meat is continually moistened with its own juices, and the process FOOD AND HEALTH. 119 nd, se-'ond, to see i properly, for the tion, but from one- oved by the water. Its should be large, at this temperature 1 quickly hardened, eded. After a few should be lowered rably below boiling, meat is sufficiently the fibres are easily at a temperature •me hard and more d soups., when the Duld be cut smaller st, the temperature about mo degrees, coagulated, and the After two or three id boiling will com- poiled until they are ed at once from the latter, and become tatoes. Green corn, rd water withdraws in soft water. It for cooking meats, /elops their flavor, eight, this is chiefly ting of fat. Roast The process should er to form a sort of cut, which will pre- i temperature must owly, as in boiling, h is much the same ivith a high temper- itewing, the meat and the process should be conducted with a low temperature. Old or tough meats are best cooked in this way. Frying is the most objectionable of all methods of cooking foods, animal or vegetable ; the heat being applied through the medium of boiling fat, the foods are rendered more difficult of digestion. Bread is a most important article of diet, as it is so uni- versally used. A vast amount of bad, unwholesome bread is eaten, especially in towns and cities, where it is chiefly made in baking establishments, and from inferior flour ; alum being used to whiten and improve the appearance of the bread. In the method of pre- paring fermented bread — that in general use — a considerable proportion of the nutrient matter is destroyed and lost in the pro- cess of fermentation. The sugar, and perhaps some of the starch, in the flour is decomposed, and alcohol and carbonic acid gas are formed. The object of the fermentation is to produce this g?s, which becomes entangled in the mass and distends or * raises ' it. In ihis way the little cavities or eyes are produced in the bread, and it is made spongy and * light.' To make good bread, good flour and fresh active yeast are indispensable. These with water and a little salt are all that are necessary. The addition of good mealy potatoes is not objectionable; but bread made with potatoes is less nutritious. The mixture, or * sponge*, as it is called, should be kept at a temperature of about 70° (F.) until it is raised sufficiently. It should then be well baked in a hot oven. The heat drives off the excess of water and the alcohol. Unfermented or aerated bread is made either by forcing carbonic acid into the dough, or by caus- ing the gas to be formed within the dough by the action of an acid (as hydrochloric) on carbonate of soda or ammonia. In this way a very nutritious, wholesome, and palatable bread may be made. Bread, especially the fermented, should never be eaten when newly baked. Most puddings, and pancakes, pastry (baked paste, with fat), and all such foods, are more indigestible than good bread, and often prove highly irritating to the stomach. It would be much better if people never indulged in such substances. Having secured plain, nutritious, unmixed food, properly cooked, The best time to eat it is when you have most leisure. In order that digestion may be performed in the most perfect and iiealthful manner, there must be a period of mental and bodily rest both before and after each meal, and abundant time must be given for the mastication and insalivation of the food. Next to this im- portant point of devoting plenty of time to the eating and digesting 8 Z20 ELEMENTARY HYGIENE. of food, is that of regularity in the time of eating. When the diges- tive organs are accustomed to receive food at or about certain hours every day, digestion is performed more perfectly and with greater ease. Perhaps you have observed that, if you are accustomed to do certain work at a regular hour every day the work seems easier when done at that hour than if done at any other. So it is with the digestive organs. Habit has much influence, in fact, over all the bodily functions. To eat three meals a day is the most uni- versal practice ; and it seems better for persons in health to eat three moderate meals a day than two larger ones, or four or more smaller ones. And from four to six hours should elapse between each meal. Of the three meals. — The breakfast is a very important meal. There has been a long fast, and most persons in good health require a good substantial breakfast; and it is usually a sign of good health and vigor when one has a desire and a relish for such a meal at any early hour. It is especially desirable that the breakfast be simple and easily and readily digested, as well as sub- stantial, or nutritious, in order that the blood may receive an early and a full supply of material. The nature of the mid-day meal, whether it be called luncheon or dinner, must depend largely upon circumstances. If you are attending school, or are engaged in some light occupation, especially perhaps during the middle part of the day, and without much exercise, a light repast, a luncheon, will supply your bodily wants until you have more leisure for a fuller meal. But for the large class of workers, who are actively employed in bodily labor, a substantial repast — a dinner, after hav- ing worked about five hours, is very necessary. Luncheon should not be too light, or you will be more liable to eat over-much at dinner. While much depends upon habit, it is generally believed that the evening meal, whether called dinner, tea, or supper, if at all a full one, should be taken at least three or four hours before bed time ; in order that the organs concerned in digestion may have nearly completed their work before the time for sleep. And whether you have eaten a full meal about mid-day, and worked hard all the afternoon, or eaten only a light luncheon, and worked less, you will need a fair, substantial meal about six o'clock. The amount of food necessary for a meal, or for the daily re- quirements of the body, varies with circumstances. It is not what is eaten, but what is digested and absorbed, which nourishes the body. Hence the amount will depend much on the degree of com- pleteness of both digestion and absorption ; a fact which is com- FOOD AND HEALTH. I2X len the diges- certain hours with greater customed to seems easier So it is with fact, over all le most uni- lealth to eat four or more ipse between ry important ons in good asually a sign i a relish for able that the well as sub- leive an early lid-day meal, pend largely are engaged ; middle part , a luncheon, leisure for a • are actively er, after hav- :heon should )ver-much at ally believed r supper, if hours before ion may have leep. And and worked , and worked ^'clock. the daily re- t is not what ourishes the gree of com- lich is com- monly overlooked. You have perhaps observed that somepeopleeat a good deal who are yet badly nourished. lixercise or work, you know, increases the demand for food ; and more food is required in cold than in warmer weather; and likewise when one is only thinly clothed than when thickly clothed. It is usually estimated that a man in full work requires from one and a half to two pounds or more of solid, water-free food per day. But it is believed, and experi- ments have shown, that considerably less than this will suffice. Most people eat too much. A very celebrated physician, Dr. Abernethy, believed that, on an average, of the amount of food a man eats, one-fourth is sufficient for his support, while the other three-fourths he takes at the risk of his health and life. Immodera- tion in eating is regarded as the first shortener of life. It has been found that all those who lived to advanced age were very temperate in eating. Over-eating is prejudicial in many ways. Organs and powers are provided for digesting sufficient food for all the wants of the system, and nothing more. If you eat more than your body requires you eat more than can be properly digested and absorbed, or used in your body ; and the nutritive organs are over-worked and become deranged. The excess of food eaten interferes with the perfect digestion of any part of the food, and the results are inferior fluids generally, and crudites in the ali- mentary canal. The quantity of blood will probably become too abundant, while its quality, by reason of the digestive and excretory organs being over-taxed, soon becomes impaired, and the circulation quickened and irregular. When in this condition, the organism is more apt to become affected with specific disease — inflammations or fevers. And then, every body has some organs which are less perfect or weaker than the other organs. Some parts of every machine are weaker and more easily broken than other parts. Some one of your organs is weaker than any of the others. The organs of your body are not like the parson's fabled chaise, every part of which, we are told, finally went to pieces at the same instant. The weakest or least perfect organ in your body l)reaks down first. It may be your stomach, or your liver, or your kidneys, or your heart, or your lungs ; whichever it is, it will be the first to become diseased from the over-work ; and the breaking dov/n of one organ hastens on the time at which others will fail. You will learn best by experience as to how much food you require. You should eat very slowly and at the same time carefully attend to the first feeling of satisfaction, rather than of satiety, which, if your stomach is in a healthy state, will be mani- 122 ELEMENTARY HYGIENE. fested, especially if looked for, just as soon as enough, or as much as the stomach can digest with ease, has been eaten. There is a moment when the relish given by the appetite ceases. But appe- tite must be distinguished from taste. A disposition or desire to gratify the palate or sense of taste with delicate viands must not be mistaken for appetite. And one great objection to more than one kind of dish — that is, a dish of meat and vegetables, for example — lies in this : by the flavor and taste of new viands the appetite seems to be resharpened and a false desire for more food is there- by created. Any great change in the diet, especially as to quantity, must be made cautiously. When you have been a long time accustomed to a certain quantity of food, if you wish to reduce the quantity, you must do it slowly and gradually. The appetite should not be coaxed, either with spices or seasonings, or bitters or alcoholic liquors. If you cannot eat moderately of plain, simple, well cooked foods you will be better without eating anything for a time, until you have a relish for such plain foods. And with these, eaten very slowly, you will not be likely to take too much. By attending to these rules, even if you have been in the habit of eating too much, you will in a little time learn to eat only about what you need. These rules do not always apply to the sick. Thorough mastication and insalivation, especially of starchy foods, are very essential, and are great aids to digestion. In chewing food, a good deal of air gets entangled in the mass and separates the particles of the food, which is then, when in the stomach, penetrated much more readily by the gastric juice, and digestion is easier and more perfect And by always endeavoring to thoroughly grind the food with your teeth before swallowing it, you will acquire the habit of eating slowly. But for perfect masti- cation, good teeth are necessary. In order to preserve your teeth you must keep them very clean and free from particles of food between meals. Very hot or iced cold foods or drinks tend to injure the teeth. And very hot or very cold foods cannot be well masticated, but are usually swallowed hastily, to the injury of the stomach. Hence you should not partake of such foods. Cold and exercise increase the demand for food, and therefore in cold weather and when taking much exercise you re- quire the most nutriment. In very warm weather and when taking but little exercise you need but little food ; but as the wea- ther becomes colder or you take more exercise you will have an api ThI thel war tier tial] limj fore inu dig^ rec«! in tl FOOD AND HEALTH. 183 1, or as much There is a . But appe- or desire to I must not be ore than one for example the appetite ood is there- lanlity, must accustomed :he quantity, with spices 1 cannot eat all be better :lish for such 1 will not be , even if you a little time not always specially of digestion, in the mass when in the c juice, and endeavoring sallowing it, 5rfect masti- eserve your particles of drinks tend cannot be le injury of foods. food, and cise you re- 'hen taking the wea- 111 have an appetite for more again. In cold weather more fats are required. The most important point perhaps in connection with this part of the subject of diet is, to take less food as the weather becomes warmer or as you adopt more sedentary habits. Careful observa- tion of the wants of the body will then be especially required. A period of repose both before and after meals is essen- tial to good digestion. When the voluntary muscles — those of the limbs and trunk — are in full action, an excess of blood and nerve force is drawn to them from other organs ; and if food is taken into the stomach at such a time it will not be readily or well digested. The digestive organs will then not be in a fit state to receive or digest food. And when food lies for even a short time in the stomach before natural digestion commences it undergoes morbid or unnatural changes — sometimes sours — and irritates the stomach. Active mental or brain work likewise draws blood from the stomach and other organs. So you should never take a meal directly after you have been actively engaged in either physical or mental work, and especially when quite fatigued from such work. You may take a few mouthfuls of some simple food if you are very hungry or weak, but you should rest — sit. or, better, lie down — for a few minutes or half an hour before you take your meal ; in order that the circulation may become equalized. So also after a meal you should not commence active work, and so withdraw blood and force from the stomach, too soon, or until the digestive process has become fairly set up, or partly completed. The general surroundings of the meals demand consid- eration. While a full supply of nerve influence should be concen- trated on the digestive organs, it is very important that the mind be pleasantly occupied. Mental depression, anxiety, and fear retard digestion, and people should not eat much when the mind is in any one of these states. The dining room should be kept cool and well ventilated ; or else blood will be drawn from the digestive organs to the skin and lungs. The light should per- haps be somewhat subdued ; a reddish shade being usually most pleasing. Sweet flowers and scents are agreeable accompaniments of the meal. Pleasant conversation during meals, and after, is a great aid to digestion ; while music and the plashing of water are agreeable, and contribute to the necessary mental condition. An occasional fast for a longer time than usual, as by omit- ting a meal, unless one is habitually very abstinent, is an excellent appetizer and promoter of the digestion and absorption of the fol- lowing meals. The digestive organs not only get rest, but a sort rr 124 ELEMENTARY HYGIENE. of cleansing and renewing ; they relieve themselves of all collec- tions and remnants of any previous excess. But after the fast more care is required to prevent over-eating. CHAPTER XV. EXERCISE AS REGARDS HEALTH. Man is designed for action. He must exercise in order that he may obtain food. It was the unalterable and almost the first destination of man that he should * earn his bread by the sweat of his brow,' A certain amount of action or exercise is then an essential condition of life. You have a most beautiful and admirably constructed jointed and flexible skeleton, and at- tached to it are nearly half a thousand muscles — making up half the gross weight of your body — the sole function of which is to produce motion : and do not all these proclaim that you are formed for physical action ? And then, compared with other ani- mals, you have an immense brain, evidently designed for great mental activity. And being thus designed, if you do not exercise your muscles and your brain in some way, these structures, and along with them, through nervous influence, all the structures in your body, will become weakened and at length diseased, from want of use. The effects of exercise are to impart a sort of stimulus to all the tissues and organs of the body, whereby their nutrition is promoted. You probably remember that I told you (page 64) that exercise of the muscles hastens or increases the flow of blood in the veins which lie amongst the muscles. The contraction of the muscles, you know, causes pressure on the veins — squeezes them, and the biood in them is pushed on more rapidly toward the heart ; the heart is then called upon to act more quickly in order to pump the blood out faster, and in this way the whole circulation is quickened, and the blood courses more rapidly in all the vessels. And as the blood flows faster through the little bits of capillaries covering the air cells of the lungs, there is a call for a greater supply of oxygen, and breathing becomes deeper and fuller ; and hence more oxygen is consumed, and oxidation and nutrition are increased throughout all the tissues of the body. It is., in short, a sort of law of most of the tissues, especially of EXERCISE AS REGARDS HEALTH. "5 of all collec- after the fast :ise in order d almost the jread by the »r exercise is ost beautiful eton, and at- iking up half f which is to lat you are th other ani- led for great not exercise uctures, and f5tructures in eased, from stimulus to nutrition is I (page 64) ow of blood ntraction of —squeezes idly toward ; quickly in the whole : rapidly in gh the little >, there is a mes deeper 1 oxidation )f the body, specially of muscle, that within certain limits, use increases their bulk and strength. Judicious exercise increases the number or size, or both, of the bodily cells and tibres, and probably produces other chemical or vital changes. The poet tells us, and truly, that ' Use, use is life ; and he most truly lives, Who uses best.' It is use — exercise, which makes the muscles on the arm of the carpenter or smith large, firm, and powerful ; and it is want of vigorous exercise which causes the arms of many boys and gir!s, and grown up people too, to be small and soft, and not very strong. With the increased circulation following muscular exercise, all the other organs or parts of the body — the bones, the nerves, the heart, the lungs, the stomach, are made stronger and better able to perform their functions. Mental exercise, in like manner, developes and strengthens the brain ; and the mind grows stronger and cr.pable of doing more and better work. Though bodily or physical exercise im- parts vigor to the whole organism, including the brain, and the brain is the immediate organ of the mind, it is only by exercise of the mind, apart, as it were, from the body, that the mental fac- ulties can be strengthened and developed. However vigorous your brain, as an organ, may become, through physical exercise, without well directed mental discipline your mind may remain in- capable of much good work. Memory is vastly improved by the judicious exercise of it ; and almost lost if not properly used and cared for. And it is believed that memory involves the develop- ment and growth of new cells and fibres. So that mental and physical exercise should go hand in hand together. The effects of too little physical exercise then are small, soft, flabby muscles, resulting in muscular and general weakness. Should you ever get into this condition and attempt to make much exertion, your heart, from being weak, would beat faster, and flutter, as if to make up for its want of power, and pumpin^^ the blood faster into your lungs, you would have to breathi; quicker and shorter, and you would be easily exhausted. When one is a long time without exercise, the muscular tissue actually changes in structure, and the bones become softer and lighter. The fibres of the muscles in the thigh of a man who has lost his leg and does not use his thigh, but a crutch, become whitish and re- semble fatty tissue, and lose the beautiful cross-marked appearance represented in Fig's. 21 and 22. The bones of the spine and extremities of those engaged in light occupations, as shopkeepers 136 ELEMENTARY HYGIENE. and tailors, are found to be smaller, and lighter in proportion to size, than the bones of those engaged in more vigorous work. If you stoop habitually and do not frequently exercise and expand the walls of your chest and your lungs to their full capacity, the size of your chest will gradually become smaller, and your lungs contracted and weaker. Too much exercise produces conditions very like the con- ditions following too little exercise. If physical exertion is pro- longed without sufficient rest, or continued long after fatigue, the destructive changes become greater than the reparative, and the muscles degenerate and become small, flabby, and weak. And this weakened condition soon extends to the entire organism. So you see that either too little exercise or too much exercise or over- work, produces nearly the same state of body — general weakness. Over-exertion is particularly injurious when the organs are growing, during childhood and youth. Mental overwork is of not uncommon occurrence, esptc- ially among those competing for prizes and honors at schools and colleges, and is productive of much mischief. If after a period of close mental application you are unable to keep your attention fixed on the subject or study on which you iiave been engaged, you should discontinue your efforts — further attempts will be lost labor — and either take some muscular exercise, or take up some other study of a lighter nature. Continued overwork of the mind, especially if accompanied with trouble cr worry of any kind, soon gives rise to wakefulness or disturbed sleep, to troubled dreams and visions, talking, moaning, and starting daring sleep, often followed in the morning by a sense of fatigue and general weak- ness, with probably weight or pain in the head, and disordered digestion ; the forewarnings of more serious troubles. Unequal or incomplete exercise gives rise to much func- tional irregularity in different organs, and eventually to disease. Very few of the many occupations by which men and women ob- tain their livelihood bring into action all parts or evMi most parts of the body. The tendency of neirly all the occupations of modern civilized life is to use, and too often to overwork, a por- tion of the body only, and to underwork the other portions. Hence a part, and frequently a large part, of the organism is not brought into that activity for which it is designed, and which is necessary to health. In some vocations, while the muscr.lar sys- tem is, for the most part, brought into action, the brain is almost entirely unused ; in others, the braii are smal T those ploy( whic engi; muse EXERCISE AS REGARDS HEALTH. 127 roportion to JS work. If and expand :apacity, the I your lungs ke the con- rtion is pro- fatigue, the ve, and the 'eak. And ;anism. So cise or over- il weakness, ire growing, ;nce, esptc- schools and ter a period ur attention igaged, you vill be lost ce up some f the mind, kind, soon ed dreams leep, often eral weak- disordered much func- to disease, women ob- most parts nations of ork, a por- portions. iism is not i which is sci.lar sys- 1 is almost le muscles are not exercised ; and in a large number, the hands only and a small portion of the brain are employed. The chief object of hygienic exercise is to supply to those portions of the body which are, for the most part, unem- ployed during the ordinary pursuits of life, that amount of action which is essential to the well-being of the whole body. If you are attending school or college your brain will get exercise enough, but you should take care that all the muscles in your body are brought into action for a certain length of time every day. Again, if you are employed at something which requires only almost constant walking about, you should engage in vigorous action your arms and the muscles of your trunk, as well as your brain, in mental exercise, for a certain period every day. In short, if you want to secure the best of health, you must bring into active use, every day, your brain and every muscle and joint in your body. On the other hand, it is an object of hygienic exercise to some- what soften and make more flexible the very hard and stiff muscles and joints of those engaged in laborious work. You must not think it is of the first importance to produce by exercise mere bulk or quantity and hardness of muscle ; the quality of the fibre must also be considered. The hard working farmer and mechanic are much benefited by engaging for a little time every day in some light, active exercise which promotes flexibility and softness of muscle, and which requires agility rather than strength For this purpose, fencing, base-ball, and the lighter forms of gym- nastics are valuable. Hence if you are obliged to work very hard, in order to preserve your muscles and joints especially in a healthy condition, you should devote a little time every day to some light pleasant exercise — to play, in short. This, with the warm bath (page 142), will tend greatly to prolong youthful vigor and activity and to retard the stiffening and hardening effects of approaching old age. organs may be The power of the will over the bodily strengthened and increased by judicious, systematic physical exer cise. There is doubtless muscular effort i.. •'.x determination to carry out certain plans, and in the unflinching resolution to bear severe pain without outward manifestation. Hence a well-devel- oped muscular system promotes ^^elf-control. Now, you know very well, much disease arises, directly or indirectly, from want of self-control, want of will power to prevent excessive indulgence in the gratification of the appetites, as, for example, in both drinking and eating. So that, you see, while muscular exercise up^ 128 ELEMENTARY HYGIENE. directly promotes health and vigor of body, it indirectly prevents disease by favoring muscular development, and thus increasing the power of the will. Regularity in taking exercise is essential, in order that you may receive the full benefit of the exercise, — regularity as to time, quantity, etc. As at school and college you receive regular, methodical mental culture or exercise, so you should receive regular, methodical bodily culture or exercise. The latter is as necessary to good physical development and growth, as is the former to good mental development and growth. And you should endeavor not to take a little of one sort of exercise in the morn- ing of one day, and a good deal of another sort in the evening of another day, but observe regularity as far as possible. Taking exercise, like taking food, should be a regular, persistent daily habit. Occasional attempts at it may do more harm than good. Exercise should be commenced moderately. The mus- cles when in motion require more blood than when at rest; and as the circulation of the blood can only be safely, if at all, increased in a gradual manner, when your muscles have been in a state of repose, you should not bring them suddenly into vigorous action. If you have a few hours' work to do, by commencing moderately, and doing a smaller proportion the first hour or two, you will be the better able to do more at a later period, and can accomplish the whole with less fatigue. If you have been for a length of tmie without much exercise, as from illness or other cause, when you commence to take exercise again, it should be at first of a, light sort, and of short duration ; and gradually the length of time spent in exercising may be prolonged, and exercises of a more vigorous character be substituted. You know that persons not accustomed to work are easily made tired ; though by practice they may acquire great powers of endurance. Perhaps you have heard about the man who commenced the practice of lifting a calf off the ground every day, and continued to lift the animal with the same apparent ease after it became an ox. As the animal grew the man's strength incrccsed. It is believed, furthermore, that it is better not to sit or lie down imtnediately after great exertion, but to leave off somewhat grad- ually, or move about for a few minutes. Exercise should be taken in the open air when possible. During active muscular exertion, nutrition being highly promoted, the demand for oxygen, and consequently for pure atmospheric air, is greatly increased, and the open air provides these in greatest EXERCISE AS REGARDS HEALTH. 129 ctly prevents Lis increasing n order that jularity as to :eive regular, lould receive The latter is ifth, as is the d you should in the mom- lie evening of )le. Taking rsistent daily I than good, r. The mus- Ltrest; and as all, increased 1 in a state of ;orous action. 5 moderately, , you will be accomplish r a length of cause, when ; at first of a, ;he length of ixercises of a that persons h by practice ips you have e of lifting a the animal )x. As the it or lie down newhat grad- hen possible. ily promoted, atmospheric se in greatest abundance. Muscular action can be continued longer without fatigue in the open air than in a closed room. When the weather prevents out-door exercise, free ventilation in-doors is very es- sential. Experiments have shown that exercise can be endured with less fatigue in sunshine than in shade, the temperature being the same. Active exercise should not be engaged in soon after a full meal, nor just before a meal, as you have been told. And in order to get the full benefit of exercise, the clothing should be loose, that it may not interfere in any degree with the free action of the muscles. The mind should be engaged in the exercise. You will be most benefited by that kind of exercise in which you naturally take the greatest interest ; while you can continue it for a longer period of time without fatigue. The walk or other exer- cise engaged in with some object in view, as that of accomplishing something agreeable, will be attended with the greatest benefit. Probably you have heard the story about the little boy who, after a long walk with his father, appeared to get very tired, and finally objected to walk any further. The father, to encourage the little fellow, gave him his gold-headed cane to * ride ' upon, when the tired boy at once became cheerful and apparently as little fatigued as at the commencement of the walk, and gave no more trouble while completing the journey astride the gold-headed cane. Of the different forms of exercise there are none pro- bably of greater value than gardening, especially if you sit a good deal, and have, or can acquire, any taste for this form of exercise. But if you take up gardening as an exercise, you should do all the work of the garden, and not the lighter work only ; the digging and trenching, as well as the planting and pruning. This would bring into action all the muscles, and occupy, and, if properly conducted, interest the mind. Besides, gardening may be made profitable ; the exercise is not lost labor. There is a great deal of force bestowed on hygienic exercises which might be turned to more profitable account, and confer, at the same time, just as much hygienic benefit. Gymnastics consist of a number and variety of scientific movements, many of which are very valuable in promoting symmetry of body anu flexibility and grace of action. They are too often considered, however, as certain feats or contortions to be done, instead of certain physiological effects to be produced upon the system. For example, some make great efforts to be able to strike the back of the hands together behind the trunk at the height of the ^imrwi 130 ELEMENTARY HYGIENE. shoulders ; whereas, it is not desirable that the shoulder joints and other parts should be so loose as to permit of this feat, and if the hands were carried only just back of a line parallel with the shoulders, the benefit would be greater. Walking and skating are valuable exercises. In walking up and down hills, and over rough ground, this exercise is more vigorous and fatiguing. When the arms are allowed to hang loosely and swing to and fro, as they always should be in these exercises, nearly all the muscles are brought into action ; those of the trunk and neck maintaining the body in the erect posture. Swinging the arms is an important part of the exercise. Walking and skating with the hands locked behind or in front, or as in carrying them in a muff, interferes with the free action of the chest and lungs, and is highly injurious. For reasons which you ought now lO be able to understand, you should keep your whole body erect, with your head and shoulders well back, giving full play to your lungs and free passage tO the air into these organs. Running and leaping are much more violent exercises, and should be indulged in with prudence and caution, especially by those who have not been gradually habituated to them. Cricket, base-ball, and lacrosse, involve such exercises, and to such games these remarks are applicable. Dancing, moderately in- dulged in, at suitable hours, in appropriate clothing, and in properly ventilated rooms, is a good form of exercise for the young. It agreeably interests the mind, while it gives full play to all the muscles. Rowing is a good exercise, and tends greatly to develop the muscles of the chest. The amount of exercise required by each individual, or of labor which each can accomplish, varies considerably with cir- cumstances and with habit. Exercise or work should never be carried so far as to produce great fatigue ; especially by those who are not very vigorous. If the exertion passes beyond the point of slight fatigue to that of exhaustion or restlessness, it has been carried too far. These remarks apply to mental as well as to physical exercise. The development of the muscles and other parts is a gradual process, and is retarded rather than favored by over-exertion, as you have been told, and instead of strength weakness will follow. An eminent physician and hygienist has told us that every man and woman ought to take an amount of daily exercise of some sort equivalent to a nine miles' walk, or 150 fool-tons, as it is called (the power required to raise one ton a foot high) ; 500 foot-tons is regarded as a hard day's work. REST AND SLEEP IN REGARD TO HEALTH. 131 •ulder joints his feat, and .llel with the In walking cise is more ^ed to hang be in these :tioH ; those rect posture. 2. Walking )nt, or as in of the chest h you ought whole body ; full play to is. :ercises, and specially by Cricket, and to such )derately in- l in properly young. It .y to all the greatly to dividual, or Dly with cir- ild never be ly by those beyond the mess, it has il as well as s and other favored by of strength ygienist has amount of es' walk, or ise one ton day's work. Any one between twelve and twenty years of age might take from one-half to three-fourths of that amount. One very injurious practice, which is not so uncommon as it ought to be among men and women, is that of taking, when tired, some sort of stimulant, tea or coffee, or some alcoholic drink, and thus lashing on their flagging powers to an injurious ex- tent, instead of ceasing their exertions and seeking rest. CHAPTER XVI. REST AND SLEEP IN REGARD TO HEALTH. After exercise or work, rest is of the first importance. It is during the period of repose that the process of repair in the tissues is greater than that of waste, and a proper balance is re- stored. So if you do not take sufficient rest, you will wear out too fast. Wherever we find a nervous system, there we also find, as it were, antagonistic to its activity, the periodical invigorator, 'balmy sleep ;' the exact nature of which peculiar and mysterious condition physiologists and philosophers have in vain attempted to fathom. All the bodily organs must have rest. Even the busy heart pauses — rests, for a brief fractional period before each beat, each contraction, or act of pumping the blood out of its chambers. The brain cannot any more than other organs continue to work without ceasing. And as it is the direct instrument of the mind, in order that it may get perfect rest, it appears necessary for us to cease to think, and so we sleep. The most perfect rest to all parts of the organism is ob- tained when the body is in the recumbent posture — lying down flat, on a level surface. In this position the heart beats slower than in any other, and the breathing is calmer, so that the organs of the circulation, and the chest and lungs, are taxed in the least possible degree, while all the voluntary muscles are entirely inac- tive. The more perfect the repose and the lower the degree of excitement, the more complete will be the renovation of the tissues, and the greater the after ability to endure labor. The wild Indian, the Tartar messenger, and the wandering Arab, yielding to a sort of instinct, when weary, stretch themselves prone upon the ground or upon mats or cushions ; and they rise again wonderfully refreshed and ready for more of their wonderful iinr 132 ELEMENTARY HYGIENE. pedestrian feats. We might take a valuable hygienic lesson from these creatures of nature. So when you are tired, instead of taking some stimulating drink, as too many do, or sitting in a stih, straight-backed chair, lie down or recline as much as you possibly can. Weariness of brain is best relieved by muscular exercise, and by sleep. Sleep is said to form, as il were, stations for our physical and moral existence ; and we are thereby daily reborn, and pr ss every morning into a new and refreshed life. And without this continual change, this incessant renovation, life would soon become insipid and wretched. Want of sufficient refreshing sleep is believed to lead to insanity. It first gives rise to nervous irritability and peevish- ness, and to general derangement of the whole organism. Nothing hastens consumption so much, or wastes us so much, and makes It; »eem old, as want of sleep. If ever you attempt to economise or save time by depriving yourself of sufficient sleep, you will make a grave mistake, and unfit yourself to do your full amount t. eitiicr mental or physical work. The ill effects may not be manifested for a long time, but they are certain to come. The amount of sleep necessary for each individual every twenty-four hours, like other hygienic essentials, varies with cir- cumstances. It depends somewhat on the temperament, or ability to sleep soundly, and on the amount of mental and physical work done by each — on the amount of exercise and wear. It is said that, of adult persons, one should not sleep less than six, nor more than eight hours ; for it is possible to take too much sleep, and thereby debilitate both mind and body. The younger we are the more sleep we require. Babies sleep most of their time ; and growing boys and girls during school life require nine or ten hours' sleep, at least. You may easily learn how much sleep you require, how much is necessary for the complete renovation of your entire body, but especially your brain. With your mind tranquil and your stomach unburdened, go to bed, habitually, at a regular and seasonable hour, in a properly constructed, comfortable bed, in a quiet, well ventilated room, and get up in the morning imme- diately, or in a very few minutes, after waking. Unless disturbed in your sleep, you will most probably not waken until you have slept enough, and you will not be at all likely to sleep too much. In this way you may soon form a habit of sleeping just long enough and no longer. You must not lie dozing or drowsing lesson from i, instead of sitting in a luch as you by muscular >hysical and i pr ss every lis continual :ome insipid i^ed to lead ind peevish- n. Nothing , and makes 3 economise ;p, you will full amount may not be ne. vidual every ies with cir- It, or ability lysical work It is said X, nor more h sleep, and r we are the r time ; and nine or ten equire, how your entire :ranquil and regular and lie bed, in a ning imme- 3S disturbed ;il you have [) too much. y just long or drowsing REST AND SLEEP IN REGARD TO HEALTH. 133 after waking, or sleep will come more tardily the next night, and will be less sound and refreshing ; and you will not be able to form or to continue a habit of sleeping soundly and well for the necessary period. The best time to sleep seems plainly pointed out to us by the mechanism of the solar system, by which the stimulation and activity of day and light, are alternated or followed by the silence and quietude of darkness and night. Few practices are more pernicious than that of turning, as it is said, night into day. The benefit of sunlight cannot then be obtained to the greatest de- gree ; and the sleep, when all nature is active, cannot be sound and refreshing. Whatever artificial light is used at night, it is not so good for the eyes, or any part of the organism, as sunlight. The eyes of night workers are very liable to suffer. It has been asserted by good authorities that two hours of sleep just before midnight are better than four hours in the day-time. Regularity as to the time devoted to sleep is very essential, and you should go to bed at as nearly as possible the same hour every night ; when sound sleep will be obtained more readily, from habit. On early rising many have become eloquent, in setting forth the advantages of being astir at an early hour in the morning, in- stead of being * couched in a curious bed.' It has been found that those who lived to old age, were, for the most part, in the constant habit of leaving their * easy couch at early day.' The morning is the freshest and most youthful part of the day, and if you spend the most of it in bed, you lose much of the best part of your life. But in order to rise early you must go early to bed ; and to rise with the sun, or soon after it, in the long days of summer, you would require to go to sleep at a very early hour. It is of more importance for you to get sufficient sleep than to get a reputation for early rising. In many localities it is better, especially during warm weather, to remain indoors until the sun has been up for a little time. Sun-light purifies the air near the surface of the earth, which during the night becomes more or less impure. The sleeping-room, you must bear in mind, is a place in which you spend about one-third of your life, and it therefore claims much consideration. It should be as large as possible, well lighted, and opened and exposed to the air by day, and well ven- tilated during the night. Do not be afraid of letting in the ' night air,' especially at the upper part of a window, which, even in ground-floor rooms, is usually three or four yards above ground. 134 ELEMENTARY HYGIENE. The uppermost rooms should be used for bed-rooms. It is a hundred times better to breathe night air than to breathe, again and again, the same vitiated air in a close room (see page 92). A good bed to lie upon is very essential to good rest and good sleep. It should not be very soft nor very hard, but mod- erately elastic. Beds receive a large quantity of waste matters from the human skin, and should be made in such a way and of such material that they may be readily cleansed or renewed. Feather beds are, happily, fast going out of use ; and much better had they never been used. Hair and wool make good mattresses, but they are not easily cleaned, and are too costly to renew often. When in constant use, such mattresses should be opened, and the contents carded and beaten and exposed well to the sun and air, at least once or twice a year. Fine wire mattresses are coming into use, and are admirable for beds. They are easily cleaned and kept clean, cool in summer, and, with only blankets over them, readily made to retain sufficient warmth in winter. Pillows may be made of the same material as the mattress ; and they require the same management. The use of feather pillows, es- pecially the large soft ones, should be discontinued. The bed-clothing should be light, and of such a kind as to be also easily cleaned. Woollen blankets are therefore decidedly best. Thick quilts and coverlets are objectionable, chiefly because they cannot be easily washed and cleaned. It is of great importance to have all the bedding thoroughly dry before it is used. Every day the clothing should be turned down and ex- posed as much as possible to the sun and air ; and the sheets should be well shaken in the open air, to free them from the emanations from the skin. No one who desires comfort and health should wear next the skin when in bed, the same article of clothing worn while at work or stirring about during the day. On going to bed, darken your room, and endeavor to lay aside with your clothes all the cares and burdens of the day. Place yourself in the easiest possible position, — that with the body and limbs rather straight, and the head slightly raised on a pillow, being best, as being most favourable to the free circulation of the blood. And, after committing yourself to the keeping of the Great Ruler of the universe, court sleep. As it is not desirable that you should remain in bed, or even in your bed-room, much longer than the hours devoted to sleep, you should not read or study in bed. When you are well, remember, the bed is solely the place for sleep. CLOTHING AS REGARDS HEALTH. 135 ms. It is a eathe, again page 92). Dod rest and d, but mod- aste matters I way and of Dr renewed, much better i mattresses, renew often, opened, and the sun and s are coming sily cleaned lankets over r. Pillows ; and they pillows, es- a kind as to re decidedly ble, chiefly It is of great before it is )wn and ex- . the sheets jm from the comfort and lie article of he day. savor to lay of the day. ith the body on a pillow, ation of the ping of the ot desirable 00m, much not read or is solely the CHAPTER XVII. CLOTHING AS REGARDS HEALTH. The principal object of clothing is, not to supply heat to the body, but to prevent the escape of animal heat from the body. Perhaps you know that some substances carry away or conduct heat better than other substances do. If you put your hand on a piece of linen cloth, especially fine linen, it feels cold, while if you put your hand on a piece of woollen cloth it feels warm. This is because the linen carries away or conducts the heat from your hand more rapidly than the woollen. Air carries heat but slowly, and is therefore a bad conductor of heat. Those clothes, then, which contain within their textures the largest amount of air, are the poorest conductors of heat ; they best retain warmth, and are said to be the 'warmest' On the other hand, the finer and denser the fabrics, and the closer they are packed in the weaving, the less air they will hold, and the * cooler' they are said to be. When, therefore, warmth and protection from sudden changes in the weather are the objects, the texture should be loose, though not loose or open enough to permit the passage of currents of air ; but up to this point, the more open it is, the better. Another property of clothing, which must be considered, is that by which it takes in, retains, and gives out moisture. Some clothes lake ia moisture very quickly, will hold but little, and hence give it out rapidly. If ever you have worn a cotton or linen shirt next your skin in warm weather when you have been perspiring freely, you doubtless observed that it became wet quickly, and felt colder than when dry. Cotton and linen readily absorb the perspiration from the surface of your body, and not having much capacity for water, they soon get wet, and give off moisture freely from the outer surface, and with the moisture heat is carried off. You remember how the evaporation of moisture or perspiration from the surface of your body keeps your body from getting too hot (pages 72 and 85). On the other hand, woollen takes in the perspiration, and also gives it out, but much more slowly ; and hence it does not feel so cold to your skin as linen or cotton. Besides woollen has a greater capacity for mois- ture, and will hold a great deal more than linen or cotton, before giving off any. Woollen cloth will hold, within its fibres, at least 9 nr 136 ELEMENTARY HYGIENE. twice as much moisture as the same weight of linen or cotton, after all have been compressed or wrung as dry as possible. The materials used for clothing are cotton, wool, linen, silk, and the dressed skins of animals — furs. Cotton is very universally worn, and forms excellent articles of clothing. It is much warmer than linen, being a poorer conductor of heat. When manufactured somewhat loosely it is almost as warm as woollen. Woollen is very generally believed to form the most valuable materials for clothing in use. Both theoretically and practically it has been shown to be the best. It affords the best protection against both cold and dampness ; and for counteract- ing the effects of sudden changes in the weather in this country it is particularly applicable. Linen is cool and suitable for very warm weather only. Silk makes warmer clothing than linen or cotton, but it is too costly for common wear. Fur is useful for outer wear in very cold weather, but it is expensive and not easily cleaned. Impervious clothing, that which will not permit the passage of air or water, and hence the exhalations from the body, should never be worn habitually. The oil-cloth or india-rubber coats in common use are very objectionable, and at most should only be worn for a brief period, as during a heavy shower of rain. For under-wear, next the skin, during the day, woollen flannel is decidedly the best. It is especially valuable for those who lead an active life and perspire considerable. For equalizing the temperature of the surface and preventing sudden chills it cannot be surpassed ; chiefly on account of its non-conducting properties and its capacity for moisture. Woollen causes gentle friction of the surface of the body, too, which is believed to pro- mote a vigorous and healthy condition of the skin. There area few who cannot wear woollen next the skin, on account of this friction, which causes too much irritation. The very finest woollen can nearly always be worn, however, but when it cannot, cotton, flannel, or silk, may be worn under the woollen. During the night, or in bed, you need not wear woolk/ next your body, except in some unusual circumstances. You never should wear the same garment next your body when you are in bed, which you wear when you are up and about during the day. There is no economy in doing so, and a change is both refreshing and healthful. Nothing makes a better bed-gown than thick soft cotton ; which should be shaken in the morning and ex- posed to light and air for an hour or two. The beneficial effects CLOTHING AS REGARDS HEALTH. 137 en or cotton, ossible. I, wool, linen, )tton is very othing. It is :tor of heat. St as warm as 3rm the most jretically and ords the best ir counteract- 1 this country table for very than linen or r is useful for ind not easily it the passage body, should bber coats in lould only be rain. day, woollen ble for those 'or equalizing dden chills it n-conducting causes gentle ieved to pro- There are a count of this in est woollen nnot, cotton, vear woolk/i inces. You dy when you ibout during lange is both ;d-gown than rning and ex- eficial effects of wearing woollen next the skin in the daytime are believed to be greatest when it is not worn during the hours of sleep. The frequent changing of the garments worn next the skin is very essential. They soon become more or less saturated with the excretions from the skin, and require to be shaken and exposed to the air or washed frequently, in orJer to preserve the skin in a clean and vigorous state. Woollens need not be washed very often if they are left off at night, and are frequently well aired and shaken. After working and perspiring, and when the exertion is finished, evaporation still goes on from the surface of the body^ often to such an extent as to cause chilliness. If you put on dry woollen clothing, as a thick coat or shawl, immediately after ex- ertion, the vapor from your body will be condensed in the wool, and will give out again the large amount of heat which was re- quired to convert the perspiration into vapor, or which was given off from the body. A woollen covering, therefore, for this cause alone, feels warm when used during sweating. If cotton or linen is used, the perspiration passes through and evaporates into the air from the outer surface, taking heat from the body with it. The color of clothing influences its value. The universal black is not economical ; and does not contribute to health. Black clothes absorb the sun's rays most freely, when directly ex- posed to the sun, as you learn by placing your hand on black cloth in the sunshine : but except in the direct rays light colored clothes are warmer than black in cold weather. White is a bad radiating color, and does not give out heat readily, but it in- tercepts and retains the heat which is given off from the body. Some who are habitually out during cold weather know from ex- perience that light colored overcoats are warmer than black,, except when in the bright sunshine. In very warm weather, in the sun's rays, as white reflects the rays best, — turns them off in- stead of absorbing them, it is cooler than black. Black clothes absorb moisture more freely than white, and hence they become damp more readily Odors and other emanations are taken in more readily, • \ by black than by white, and it is thought that the contagions of disease are there- fore more likely to be carried and communicated to others by black than by white. White is therefore recommended for the dress of nurses and hospital attendants. The manner of wearing the clothes is of the first import- ance. Any fabric or color improperly put on may cause disease. 138 ELEMENTARY HYGIENE. All clothing should be loose, so as not to compress, in the least degree, any part of the organism. Compression of any part of the body, especially of the young and growing, interferes with perfect development and growth, and is a source of disease. Tight fitting garments of any sort are not so warm as those which are loose. You have probably learned this already, if you have ever worn tight boots or tight gloves. The loose dress encloses more air than the tight one ; while the lattt ^rferes with the free circulation of the blood, and hence, witu the generation and dis- tribution of heat in the body. The effects of tight clothing are sometimes of a serious character. Compression of the chest and abdomen by corsets or stays is a fruitful cause of disease ; doubtless often giving rise, more or less directly, to dyspepsia, liver affections, and con- sumption. In these cavities are the great organs of supply and waste, and there is no part of the body where free action, and free circulation of the blood, are more essential ; and no part is so greatly and so universally constricted. The perfect perforuiance of every function of the body depends much on the greatest free- dom of action being permitted to the vital organs in the region of the waist. You never should wear yoi • clothes so tight about your waist as to prevent them slipping ( i over your liips ; but have them supported by straps over yc>- lOulders. You must, especially, allow your lungs full play and be able to breathe full and deep, or you cannot continue healthy and vigorous. With any tight clothing around the chest you cannot expand your lungs to their fullest capacity. Enlarged and diseased veins of the leg are not unfrequently caused by tight garters. Garters are less objectionable when worn above the knee ; but stockings should be supported in some other way, as by other clothing suspended from the shoulders. Tight boots give rise to corns, bunions, and in growing toe-nails. The sole of a boot or shoe should be quite an wide and somewhat longer than the foot when the weight of the body is resting upon it. The amount of clothing required by each varies much with the constitution and vigor of the individual, and with habit and use. Those who lead au active life and have a well devel- oped chest and digestive organs, and a vigorous circulation, require much less than those with an opposite constitution. While you may accustom yourself to a moderate amount of clothing, you should exercise caution in any attempts to 'harden * yourself by wearing too little. Too little clothing permits the rapid escape npress, in the n of any part nterferes with isease. Tight ise which are ^ou have ever jncloses more with the free ation and dis- :s of a serious 1 by corsets ; often giving ions, and con- >f supply and e action, and d no part is so t performance ! greatest free- 1 the region of so tight about our hips ; but 1. You must, o breathe full ;orous. With ,nd your lungs unfrequently ionable when orted in some le shoulders, ving toe-nails, ind somewhat jsting upon it. varies much nd with habit a well devel' ation, require While you clothing, you * yourself by ; rapid escape CLOTHING AS REGARDS HEALTH. 139 of heat from the body, and the surface becomes cold, and the little blood-vessels in the skin contract and get smaller, — as you know everything does with cold — draw up, and too much blood is forced into the inner organs. You get chilly, cold, and inward congestions and inflammations follow. Neglecting to take or wear an extra coat or shawl on going out has cost many valuable lives. Over-clothing, on the other hand, leads to accumulation of heat, and to relaxation and debility, and when confined to par- ticular parts, the vessels there become distended or congested with blood. The practice or fashion of unequally clothing — that of loading the trunk with a large quantity and suffering; the extremities to be but thinly covered, is very pernicious. This practice is adopted to a lamentable extent in the clothing of chil- dren. You should always wear such clothing as will keep your feet and hands always warm. In cold weather wear loose mits instead of gloves, which keep your fingers apart and permit loss of heat, and thick woollen stockings or socks. Felt boots are warmer than leather. The clothing should be light. Weight does not imply warmth, and it is often a source of much discomfort. Warmth is better attained by several layers of light, loose fitting material than by fewer layers of that which is thicker and heavier. It is not the clothing itself, but the air imprisoned in its substance and between its different layers, which retains heat and keeps you warm. This is important for you to remember. Some other points for you to bear in mind in regard to clothing, are the following : Exercise, you know, increases the development of heat in the body, and you cannot work much or take active exercise when you are thickly clothed, or you would soon be overcome with heat, because it could not escape fast enough ; but when you leave off the exertion, the evaporation and loss of heat still goes on, while the generation of it in the body becomes less, and you should at once put on more clothing in order to prevent chilliness. In the evening, too, when the atmos- phere is usually cooler, and when there is less bodily energy, you should put on additional clothing. You may thereby prevent troublesome ailments. Sudden and great changes in the quantity of clothing are bad. Changes from thick to thinner clothing, especially as regards under garments, should be made gradually, and usually in the morning, when the vital powers are greatest. You should not wear only the same amount of clothing in very cold, \iTTT 140 ELEMENTARY HYGIENE. which you wear in moderate weather, on any part of the body, as some do ; but increase or lessen the quantity according to the seventy of the weather, even during the same day. CHAPTER XVIII. BATHING AS REGARDS HEALTH. Bathing or washing is most essential to good health. In order to be free from all excremental or waste matters, the whole surface of the body must be frequently washed. You re- member that the thousands of sweat glands in the skin are con- stantly giving off, through their little ducts (the pores of the skin), more or less perspiration, which is water containing some salts and organic or animal matters — refuse substances which you have done with, for which you have no further use (page 85). The water passes off as vapor through your clothes, but most of the salts and animal matters remain on your skin or in your clothes. Then the outer dried cells of the cuticle are being constantly rubbed loose, and remain on your skin or underclothing unless washed off. Now you do not want to carry about with you a lot of dead, cast-off, waste stuff, and hence you must frequently wash your skin and clothes, especially your underclothes. If you do not wash frequently, these dead matters accumulate, and the little openings of the glands or ducts get clogged, and the perspir- ation, with more worn-out matters, cannot get out of your body freely enough, but accumulate in your blood. And so the blood, instead of being purified b;' the glands of the skin, soon becomes impure. The kidneys now endeavor to do the work which the skin, by reason of these obstructions, is unable to do ; but they cannot do it perfectly, along with their own special work, and are over-taxed in the effort. When you are in this condition you are not well or in good health. If you should now be attacked with any particular or specific disease, as inflammation or fever, it would much more likely be severe, or destroy your life, than if your skin were ^.lean, its pores open, and your blood pure. Fevers are well known to be more severe and fatal among uncleanly people. Furthermore, you know that the heat of your body is regulated and kept within healthy limits by the evaporation of moisture, chiefly the perspiration, from the skin (page 72). If free perspir. !l I he body, as ling to the ood health, "natters, the You re- in are con- )f the skin), some salts :h you have The water le salts and Then the bbed loose, led off. ,ot of dead, wash your you do not ,te, and the the perspir- r body freely Dod, instead nes impure, he skin, l)y ^ cannot do ; over-taxed not well or y particular much more were v. lean, I known to is regulated f moisture, ree perspir. BATHING AS REGARDS HEALTH. 141 ation is obstructed, by reason of the pores of your skin being par- tially closed, the temperature of your body cannot be regulated as it should be, and disordered functions will certainly follow. Again, bathing not only makes the skin clean, but it invigorates the cutaneous circulation. And you are less likely to take a 'cold* from a sudden chill when your skin is in a clean, healthy, and vigorous condition. Finally, the skin may be regarded as the organ of touch — feeling. In the papillae of the skin (page 40) are innumerable nerve twigs, and in order that the skin may per- form all its functions properly, it is most essential that the surface of these little prominences be kept clean and unobstructed. There are many kinds of baths, as the cold bath, warm bath, hot bath, the sponge bath, shower bath, plunge bath, and the vapor bath. While it is the chief object of the bath to clean, purify, and invigorate the skin, and so preserve the health, some baths have a curative effect : the hot bath promotes the flow of blood to the surface and thus relieves inward congestions ; the shower bath is used to relieve certain nervous disorders, as well as to strengthen the skin ; and the warm bath is a great equalizer of the circulation and soother of the nerves. The temperature of the water for ordinary bathing may vary from that near the freezing point (32" F.) to about Mood heat (98° F.). But you never should immerse your whole body in water above this degree of heat, or perhaps 96° or 97° (F.), except under the advice of your physician. Above that heat would be a hot bath, which should not be used habitually. On the other hand, but few individuals can bear with advantage to immerse the body, for even a short time, in water much below 60°. Water at this low temperature soon absorbs a large amount of heat from the body, and cools it too fast. When one is en- gaged in the exercise of swimming, a much lower temperature can be borne with safety, and for a longer time, than when resting quietly in the water. The warm bath should have a tempera- ture nearly equal to that of the blood, or from 92" to 97°; most persons require the higher degree of heat When the water is below 92° it forms a tepid, cool, or cold bath, according to temperature. These, sometimes preceded by the vapor bath, to promote perspiration, are most useful for cleansing and at the same time for invigorating the skin. Cold bathing must be practised with some degree of caution. When cold water comes in contact with your skin, the little blood- vessels near the surface contract, get smaller, and blood is forced 142 ELEMENTARY HYGIENE. from them into the inner organs. If you are vigorous and well^ on leaving the water, or before leaving it if you remain in it some time and rub the skin with youi hands or exercise in the water, the blood is driven back again to the surface, and the skin gets more or less red. This is called reaction. If this bath is not followed by good reaction and a feeling of freshness and invigor- ation, or especially if there is a feeling of chilliness, you should not repeat it often, but use warmer water, or expose less of the body to the water at the one time. Warm bathing, it is believed, may produce most valuable hygienic effects ; though the nature of it is not generally under- stood. The warm bath, at the proper ♦■^mperature, diminishes the frequency of the pulse and of the spirations, equalizes the circulation, and causes the blood to flow with greater ease and freedom throughout all parts of the body ; while it soothes and tranquilizes the nervous system and promotes general healthy action. It is popularly believed that the warm bath is debilitat- ing; but this is a popular error. The frequent use of the hot bath debilitates; but so long as the temperature of the water does not quite equal, or exceed, that of the blood, it will not debilitate, but strengthen. The great Hippocrates, the father of medicine, as he has been called, laid it down as a rule that the bath enfeebled when its temperature exceeded that of the body, or 98°. The celebrated traveller, Bruce, tells us that when he felt an almost intolerable inward heat and was so exhausted as to be ready to faint, a warm bath soon made him feel as much invigorated as when rising from bed in the morning; and that, much better than the cold one, it restored his strength after being over heated and fatigued by physical exertion. Ihe ancients evidently regarded the warm bath as restorative and invigorating, and they dedicated their warm springs and baths instead of their cold ones to Hercules. Another popular error is that, the warm bath renders the system more liable to take * cold.' But those who have recorded their experience of it declared they were less sensible to cold after the bath than before it. The warm bath is believed to retard the approach of the effects of age. While it soothes and invigorates, it relaxes and softens the hardened and rigid fibres of old persons. Its value in this respect was known in the time of Homer. Perhaps you have heard of the tradition of ^son being restored to youth by the medicated cauldron of Mecca ; which was probably a typical representation of the warm bath retarding the approach of old BATHING AS REGARDS HEALTH. I4J s and well, in it some the water, i skin gets bath is not id invigor- ^ou should less of the 3t valuable ally under- diminishes [iializes the r ease and Dothes and ral healthy s debilitat- le hot bath ir does not )ilitate, but edicine, as enfeebled 98°. The an almost e ready to gorated as )etter than »eated and regarded dedicated Hercules, the system rded their i after the the effects id softens lue in this you have th by the a typical ch of old age. This bath is without doubt a wonderful restorative when- ever one is exhausted by either physical or mental labor. A thermometer should invariably be used when taking a warm bath, and the temperature of the water should h:;'-dly reach 98°. It may be necessary to add from time to time a little hot water to the bath, as it will gradually get cooler in a room at an ordi- nary temperature, of about 65°. One may remain in the water an hour or more, though from ten to twenty minutes is usually a long enough time. Many lie and read in a warm bath. The sponge or hand bath is the simplest of all. In it you just wash over the entire surface of the body, as you wash your face, with a sponge or cloth or the hands. The warm hands for applying the water are more agreeable, or less disagreeable, to the skin than is a sponge or mitten, a',d they answer every purpose. Two or three quarts of water in a dish, and a coarse towel, are all that are necessary for this wash. A thin, easily dried mat or a piece of oil-cloth to stand on is desirable. If the room is cool, only a part of the body need be exposed at the one time. Much colder water may be used for this bath than for immersing the whole body. A little friction of the skin with the wet hands has a soothing and beneficial effect. Of other forms of the bath, the immersion of the whole body, the plunge bath, is the most common. But for it a large amount of water is necessary, and this cannot always be obtained. This sort of bath, and also the shower bath — in which the water falls from a height in drops upon the skin, when the temperature of the water is below 60°, or even 70°, produce a sort of shock to the skin and body generally, and when good reaction follows, when the skin gets red and aglow on being dried, they invigorate the skin and the body, and render the system less susceptible to colds from sudden changes in the weather. The vapor bath consists of either dry or moist air heated from 5' to 50° above blood heat. It causes free perspiration and loosening of the outer dried cells of the cuticle, and thus aids greatly in opening the pores and cleansing the surface of the skin. It is in very general use in Eastern Europe. When in health, the body should be afterwards washed with tepid or cool water. The safest rule in bathing is to take habitually that sort of bath, and at that temperature, which gives you the most after comfort. You can learn only by experience what will suit you best in this respect. Commence with warm or tepid water and gradually, from time to time, use it colder and colder until you K. 144 ELEMENTARY HYGIENE. find what agrees best with you. Whether you use the warm bath habitually or not, frequent cool or cold bathing is desirable for promoting vigorous action of the skin. Whatever you do, don't neglect to take a bath — a wash, of some sort, every day, to wash the waste dead matters off your skin. The best time to bathe must depend on the circumstances of your life. You never should bathe when there is much or any food in your stomach, but with an empty stomach. As the bath attracts blood and nervous influence to the skin, it interferes much, at the time, with the digestion of food. Most people prefer to bathe on first rising from bed in the morning ; and as many accu- mulate heat when they are in bed, and their skin is a little hot in the morning, this is a good time to bathe. If you work and per- spire much during the day, it is very refreshing to bathe j ust before going to bed. But you cannot with equal benefit use the water so cold at night as you can in the morning when you have most vigor. While it is not safe to plunge into cold or even cool water when one is over-heated or very warm from exertion, you never should take a cold bath when you feel at all cold or chilly, nor when you are in the act of cooling off after exercise, but only when you are, at least, very comfortably warm. The eyes, ears, nostrils, mouth, and teeth must not be overlooked, but should be thoroughly washed daily, or oftener, if you wish to preserve the full vigor and usefulness of these parts. The teeth should be well washed with warm or tepid water after every meal, using a soft brush at least once a day. A very soft, smooth dentifrice may be used occasionally with advantage. CHAPTER XIX. RECAPITULATION OF THE CHIEF CAUSES OF DISEASE AND HOW TO AVOID THEM; AND WHAT TO DO IN CASES OF SICKNESS AND CERTAIN ACCIDENTS. The chief causes of disease, then, as you have learned, are breathing impure air, drinking impure water, errors in viiet, over-work, and want of rest and sleep, want of exercise, improper clothing, and neglect of bathing and cleansing the skin ; the con- tagions of contagious diseases, too, demand special notice. There are two or three other important causes, to which however I can hardly allude in a book of this sort. CHIEF CAUSES OF DISEASE. MS warm bath esirable for -a wash, of T your skin, cumstances luch or any As the bath •feres much, e prefer to many accu- little hot in )rk and per- ; just before ie the water have most 1 cool water , you never " chilly, nor ;e, but only nust not be or oftener, these parts, water after \ very soft, itage. EASE AND CASES >. ve learned, ors in diet, , improper 1 ; the co.n- tice. There vever I can Breathing impure air is a most common cause of disease. The chief impurities come from the lungs and skin of the human body, and from decaying matters of one sort or another, most commonly waste, excremental matters. They enter the circula- tion through the lungs, with the air, poison the blood, and inter- fere directly with the perfect healthy action of organs. You must •avoid breathing these or you cannot possibly keep in the best of health. The only way to avoid breathing impurities from the lungs and skin in all enclosed places — rooms, shops, etc., i? to admit, in some way, abundance of fresh, out-door air, and to r /r«.i- -vide some means for the impure air to escape ; — in short, to ven- tilate. Keep all decaying matters far away from inhabited places. The use of impure water is another common cause of disease ; chiefly water from wells which receive washings and soakage from decaying excrement — from house, or stable, or yard. Such water, though often clear, has often a slightly softish, saltish taste. If you drink it, if it does not soon make you severely ill, it will certainly injure your health. Avoid it entirely. Errors in diet, as a cause of diseases of the milder sort, is probably more fruitful than any other. Indigestion, dyspepsia, ■constipation, etc., with their long, surely-following train of disa- greeable, life-destroying symptoms, are caused by errors in diet. Besides, the system is thereby made more liable to acute and serious ailments. A large proportion of the cases of sickness in children are caused by over-eating, and eating improper food. If you would be well and strong, you must eat slowly and moder- ately, at proper times, of good, plain, well cooked food ; and not mix many sorts together in your stomach, nor drink much while you are eating. Over-work, with want of rest and sleep, doubdess often cause disease ; while want of exercise, also, not unfrequently gives rise to debility and a diseased condition. You must avoid both extremes. Never try to do a too large amount of work '.n a certain time. After great or even considerable exertion, when the powers of the system are depressed, great care is required to prevent chills and colds. Many, many cases of sickness, ending in death, have been caused by chills just after working or exer- cising freely and perspiring. Hence, Improper clothing is sometimes a cause of most serious dis- ease. You do not clothe properly if you do not put on after exertion and free perspiration, or after a sudden cold change in the weather, extra warm woollen clothing. Tight clothing, espe- II > 146 ELEMENTARY HYGIENE. cially about the waist, remember, gives rise to serious disease ; as likewise does the unequal clothing of children, and also of girls and women, leaving the extremities or neck and shoulders almost bare, sometimes with over-clothed trunk. Neglect of bathing and cleansing the skin is a cause of disease. If you do not keep the surface of your body clean, bear in mind, the pores of your skin will get obstructed, and waste matters will accumulate in your blood. You cannot then be well, and you are more prone to take colds and serious illness. Every one should wash the whole surface of the body every day. Contagions and infections (seeds of contagious diseases) are direct causes, through the agency of air and water, of very many diseases and many deaths. Never go near to, or to the house of, any one who is or has recently been suffering from any contagious disease, especially scarlet-fever, measles, whooping- cough, diphtheria, typhoid fever, or small-pox ; unless you chance to be particularly required to take care of or nurse the patient. When possible, nurse and attendant should be selected who have already had the disease from which the patient is suffering. It but very rarely happens that any one of these diseases attacks the same individual the second time. After having had any such disease yourself, never be so heartless as to go near any one — to school, or church, or public place, until you have perfectly recov- ered your health, and your skin has become quite clean, and you have taken a thorough bath, with some disinfecting soap, four times, at intervals of two days. You must also exercise the greatest care in regard to any clothing which may have become infected through being near you when sick or convalescing. Clothes may hold infection for a long time. Before exposing others, have all possibly infected clothing which you wear, disinfected (page 148) and thoroughly exposed for a long time to air and sunlight, or destroyed. Without such care you may give the disease to others, and so it might spread to hundreds of persons. It is a serious mis- take to expose children to any contagious disease in order that they may get it and ' have it over.' However strictly we may conform to the laws of health, so far js our present knowledge guides us, though we shall often be able to prevent disease and preserve our bodies in good health, and thus to prolong life, more or less disease of one kind or ano- ther will fall to the lot of almost every one. We must therefore be prepared for sickness, and we should know, every one of us, something about the means by which health may be regained isease; as JO of girls srs almost a cause of :lean, bear md waste ;n be well, s. Every ay. diseases) r, of very or to the from any whooping- ou chance le patient. who have fering. It ittacks the any such y one — to :tly recov- ), and you soap, four le greatest e infected othes may s, have all page 148) inlight, or to others, :rious mis- • that they 1th, so far m be able ealth, and id or ano- therefore ;ry one of : regained IN CASES OF SICKNESS OR ACCIDENT. 147 when it chances to have been lost ; for something more than a physician and medicine is required. Then accidents will hap- pen, and may happen to any of us, and sometimes the prompt and timely application of a little knowledge in regard to the means of giving immediate relief, before a physician can possibly be obtained, may save a life. THE SICK ROOM. When any one is very sick, more especially with any conta- S^ious disease, the patient should if possible be placed in a large room, on that side of the house most exposed to sun-light. And that quietness may be secured, and any contagion as far as possible avoided, it is very desirable that the room be isolated far away from living and bed rooms, and in the uppermost part of the house. This will give, at the time, extra trouble to the attendants, but it will make recovery more certain and speedy, and in the case of a contagious disease, there will be much less danger of others getting ill with it. The walls of the sick room should be free from hangings of every sort, pictures, curtains, etc., and the less carpet on the floor the better; only strips to walk on should be permitted. If possible the walls should be varnished, and the floor waxed or coated with some water-proof paint, the cracks between the boards being well filled. The bed should stand out a little from the wall on all sides, and be free from curtains. A fine wire mattress and sheets and blankets alone make the best bed, all being easily cleaned. It is of the first importance to always secure an abundant supply of pure out-door air, and, usually, plenty of sunlight ; oc- casionally in some diseases physicians think it best to darken the room. For the purpose of ventilating, it is very essential to have in the room a grate or some sort of open fire-place ; an open grate stove will answer. And unless the weather is very warm, so that doors and windows may be widely opened, there should always be a little fire, a very little will suffice, to draw off the impure air. If there is no special opening, fresh air should be let in by low- ering the upper sash of a window ; or if the weather is very cold or windy the lower sash may be raised an inch or two and the opening at the bottom be closed in some way, as with a shawl, when sufincient air will enter between the sashes. The tempera- ture of the room should be kept uniform or regular, and the use of a thermometer is indispensable ; this should hang near the bed and register not more than about 65° (F.). , rrr ii fi' 148 ELEMENTARY HYGIENE. After recovery the room must be well cleaned, disinfected, and whitewashed. NURSING OR ATTENDING THE SICK. In sickness, everything which can in any degree contribute to the patient's comfort of body and quietness and tranquility of mind, will assist, often more even than will medicine itself, in the recovery of health. The sick should be kept perfectly clean in every respect. The frequent bathing of the body all over with warm, tepid, or cold water is very desirable, especially in all sorts of fevers. Usually the mouth and teeth require to be repeatedly washed. All discharges from the sick — from the bowels, kidneys, lungs, or stomach, should be closely covered and removed from the room as soon or as frequently as possible. These excreta may, and invariably should in a case of infectious disease, be received at once in a vessel containing a solution of carbolic acid or other disinfectant, and be carried away a safe distance and buried. Fragrant flovvers are usually pleasing to the sick, and should find a place in the sick room. In most cases perfect quiet should be observed, and whispering and low talking avoided. Visitors, except most intimate friends, and frequently even '.hese, are very objectionable. Any food or drink, even water, to be used by the sick, or any one else, should never be allowed to remain, even for a few minutes, in a sick room. You have heard something about disinfectants (page 100). Abundance of fresh out-door air is the best of all disinfectants. By its very abundance it so dilutes and disperses impurities that they have but little power for harm ; and as it contains more or less ozone, the impurities are soon thoroughly destroyed by it. In case of infectious diseases it is recommended to hang a sheet, kept wet with some odorless disinfectant, as a solution of perman- ganate of potash, just inside and across the door of the sick-room, and to sprinkle a like fluid about the room from time to time. An excellent disinfectant is made by mixing i ounce of rectified oil of turpentine, 7 ounces of benzine, and 40 drops of oil of verbena. Clothing, bedding, carpeting, furniture, paper, etc., may be saturated with it without injury. TO ARREST BLEEDING FROM WOUNDS. Should you ever be present when any one is losing^ much blood from a wound in any one of the limbs, in which perhaps a large blood vessel has been cut or injured, cut or tear lisinfected^ contribute inquility of :self, in the :tly clean 11 over with in all sorts repeatedly lis, kidneys, loved from ese excreta disease, be irbolic acid istance and e sick, and ises perfect ng avoided, even '.hese, vater, to be allowed to (j)age loo). isinfectants. )urities that ins more or -oyed by it. ing a sheet, I of perman- i sick-room, to time. I ounce of 40 drops of ture, paper, ing much S, in which cut or tear IN CASES OF SICKNESS OR ACCIDENT. 149 up the clothing quickly, and feel above the wound for the throb of the large artery supplymg the limb with blood, and press your fingers firmly on the vessel, pushing it in against the bone. If the bleeding is from the arm, feel for the vessel in the arm pit or down the inner side of the arm; if from the leg or thigh, feel for the vessel in the groin, on the inner side of the thigh, or behind the knee (see chapter on circulation). If you press hard enough the loss of blood will be greatly lessened. If there is any one near to help you, have a strong band, a necktie or handkerchief, tied loosely around the limb near where you press, or just above the wound if you have not found the vessel, and pass a rule or stick between it and the limb, and twist the bandage as tightly as the sufferer can bear without great pain. If you have found the large artery, before twisting the binder, put a small thick fold of some- thing, as a handkerchief, or piece of a shirt folded small, for a compress, over the vessel, under the binder. You may then cease to press with your fingers, and control the loss of blood by twist- ing the bandage, until a physician arrives. By such means promptly applied you may chance to save a life. In less COpious bleedings from wounds of smaller vessels, a handful of dry earth held or tied firmly on the part may arrest the flow. In very copious bleedings from wOUnds about the temple or in the neck you might render aid by making firm pressure on both the large arteries in the neck, just above the collar bone. Even in case of bleeding from a wound in the groin you might prolong life by firm but gentle pressure on the large aorta, just below the stomach and above the little fold of skin cdled the navel, especially if in a slight or thin person, in whom you can usually feel this artery throb. Never, in giving assistance in case of accidents of any sort, be in too great a hurry. Without delay, act calmly, and think for a moment what is best to do. Search carefully, but not too hastily, for the blood vessel you want to find ; having found it, press gently but harder and harder until the flow of blood is lessened. If you fail to find the leading vessel, try a compress of earth, or anything almost you can get, directly over the wound, or above it. But remember, in all cases of severe bleeding, the only thing to be relied upon is pressure. In bleeding from the lungs, when the blood is coughed up (not vomited), and is bright scarlet in color, and more or less frothy, you might lessen the immediate danger by endeavoring to soothe and calm the sufferer; first, by being calm yourself 150 ELEMENTARY HYGIENE. Have the person lie with the head and shoulders well raised ; en- tirely prevent talking or exertion of any kind. Give a little vinegar with cold water to drink, and sponge the chest with cold vinegar and water. BURNS AND SCALDS. If ever you chance to be near any one whose clothes are in flames, throw the person at once on the ground or floor, and -quickly wrap a large coat or shawl or piece of carpet around the body, and you may thus extinguish the flames ; and then, as ■quickly as possible, have the clothing all thoroughly wet with cold water, to put out any burning cinders. In case of scalds, wet the parts, clothing and all, as soon as possible, with cold water. If the skin has been burned or scalded, get a very sharp pair of scissors, or a knife or a razor, and cut off the clothing. Use the greatest gentleness, and whatever you do, don't further endanger life by trying to save the clothing, and increase the suffering of the patient. Let everything be so cut that it may be taken off with the greatest ease. If any part adheres to the skin let it (remain, and do not break any blisters. The most important thing to do next is to keep the air ifrom the burned skin. And this is best done by laying over the burned parts thick folds of cotton batting spread with fresh lard. If batting and lard are not at hand, use several layers of light cotton cloth and any sort of oil, until better can be had, or the doctor comes. If the injury is extensive, and the sufferer pros- trated and weak, give some warm stimulating drink — wine or spirits and water. FITS OF DIFFERENT SORTS. In these alarming affections but little can be done during the attack ; though their recurrence may sometimes be prevented by proper remedies. When any one falls down in a fit, as quickly as possible loosen all tight clothing, especially about the neck or head. If the face is dark, florid, the limbs motionless, and the breathing slow and like deep snorinr^, raise the head and shoulders well, but be careful not to bend tne neck. Some- thing hot should be applied to the feet and calves. When there is a stiffening, jerking, or throwing about, of the limbs, and great struggling for breath, you can only try and prevent in- jury to the limbs by gently restraining them ; and if possible place a stick or folded handkerchief between the teeth to prevent the biting of the tongue. In like convulsions of infants or IN CASES OF SICKNESS OR ACCIDENT. »5i il raised ; en- Give a little est with cold thes are in or floor, and ;t around the and then, as wet with cold scalds, wet h cold water, sharp pair of ig. Use the tier endanger e suffering of be taken off he skin let it > keep the air lying over the th fresh lard, lyers of lighi i had, or the sufferer pros- nk — wine or le during the prevented by as quickly as the neck or ionless, and lise the head eck. Sorae- When there ; limbs, and i prevent in- ossible place prevent the infants or young children, apply mustard to the feet and calves till the skin is well reddened, and cold to the head. A hot bath, at a tempera- ture of about ioo° to I02** (F.), for five or ten minutes, or until the skin gets red, would be useful. In a fainting fit, the person lies as if dead, very pale, and breathing and pulse at the wrist imperceptible. Never raise the head in the least, by any chance, of one in this state, but leave it low on the ground or floor. Pass sal volatile under the nose, and bathe the forehead and lips with brandy or some alcoholic spirits. If this does not succeed, sprinkle cold water on the face, and shout near the ear. WHAT TO DO WHEN POISON HAS BEEN SWALLOWED. When any one has swallowed a large dose of irritating poison, anything that has blistered the mouth or throat, or caused pain in the stomach, give a large quantity, say a teacupful, of sweet oil, if it can be at all readily obtained, or if not. any bland oil, linseed or even fish oil, melted lard, cream, or beaten eggs ; en- deavour to produce or encourage vomiting, by copious draughts of warm water with teaspoonful doses of mustard or ipecac. Tickling the back of the throat with a feather, if it is not too badly injured, may help to start the vomiting. If one of the strong acids — oil of vitriol, aqua fortis, or muriatic acid, has been swallowed, give at once, after the oil or before it, copious draughts of water, warm if at hand, if not, cold ; and give chalk, or mortar from a wall, broken fine, or carbonate of magnesia (a light floury powder). If potash, strong lye, or ammonia (hartshorn) has been taken, give abundance of water. If arsenic, strychnine, or oxalic acid (salts of sorrel), also give large draughts of water, with mustard or ipecac. If abun- dance of iron rust can be obtained, give it freely in case of arsen- ical poisoning. For strychnine, give 15 to 20 drops of iodine tincture, if at hand, with water. For oxalic acid, give chalk or carbonate of magnesia. If tartar emetic or white vitriol, plenty of warm water. If corrosive sublimate, give the white of eggs until the vomited matter becomes transparent instead of white or opaque. For any form of opium — laudanum or morphia — alcohol, or ardent spirits, encourage free vomiting with warm water and salt and mustard, and use every means to prevent sleep or stupor. Keep the sufferer on his feet, or drive him in a cart or wagon fast over a rough road. Give strong coffee. 10 rrmmfi 152 ELEMENTARY HYGIENE. For prussic acid, bitter almonds or ratafia, if possible, produce vomiting, and give of liquid hartshorn 30 or 40 drops in water, or keep it under the nose constantly with a feather. TO RESTORE THE APPARENTLY DROWNED : The two great objects are to get the patient to breathe again, and to restore warmth. Wait not for anything, but the instant the body is out of the water, turn it with the face downward, or on the belly, and standing astride it, raise the middle of the body as high as you can, keeping it up while you could rather slowly count five, but not raising the forehead off the ground, and giving a jerk or two, to remove water and mucus from the air passages. Some one should at the same time grasp the tongue with a dry cloth, and draw it forward out of the throat. The jerking, with the head down, may throw the tongue forward. Now let the body down and raise the shoulders, with your hands under the arms, keeping them up while you could count three. Lay it down again quickly, with the face a little toward one side, to free the mouth and nose, but with the neck straight ; and now with your elbows against your knees, still astride the body, and your hands upon the sides of the chest, over the lower ribs, press inward with increasing force while you could count two. Then suddenly let go and raise the shoulders as before. Repeat these alternate movements of raising the shoulders and of pressing on the ribs, 15 or 20 times every minute, to imitate breathing. Though air once breathed is very objectionable for breathing again, it is recommended in extreme cases like this for some one to breathe into the mouth or nostrils. This may be best done when the shoulders are raised. A friend, after taking a full inspir- ation, may put his mouth directly to the mouth or nostrils of the patient, and blow in, or pass a quill or other tube into one nostril, and blow through it. The nostril must be firmly closed around the tube, and the other nostril and month must be closed, so that the breath blown in shall not pa s diu ^.y out by the nostrils or mouth. While all this i'^ done, especially if the body has been in the water lonj. ,.gh to get ry cold, which you may learn by pressing your nd firmly for a, few moments on the skin of the trunk, have some one cm off the wet clothing, if any, and wrap the body well in dry warn, blankets or clothing from by- standers. Before putting on clothing, if a warm batl be procur- able, pat the body in one, with a temperature 01 100", for lo or 15 minutes, to restore warmth. If no means for this, apply IN CASES OF SICKNESS OR ACCIDENT. 153 , if possible, • 40 drops in ather. to breathe anything, but ft'ith the face it, raise the up while you ehead off the r and mucus le time grasp of the throat, ngue forward, h your hands count three, ard one side, ;ht ; and now the body, and ver ribs, press two. Then Repeat these iressing on the for breathing "or some one be best done g a full inspir- lostrils of the to one nostril, zlosed around ;losed, so that )y the nostrils if the body d, which you )ments on the ithing, if any, .hing from by- tl be procur- 01 100'', for for this, apply warmth in any way — with flannels from hot water or bottles of hot water to the arm-pits, groin, stomach, and feet. If no hot water can be obtained, use friction with warm hands under the clothing. When the body is in the bath, on the back, stretch the arms up beside the head, rather slowly, and then bring them down again to the sides, and press firmly on the lower ribs, endeavoring to imitate breathing in this way and repeat the movements 15 or 20 times a minute. Restorative means like the above should be continued 3 or 4 hours, if breathing is not sooner established, before giving up hope. When breathing has but just ceased, a vigorous twist of the hair or a slap on the face may restore it. When the body is on the back, have the tongue held forward. After breathing is restored, a little spirits and some hot drinks may be given. Be careful as the body gets warm not to get it over- heated. A physician should be obtained as quickly as pos- sible. All danger is not over when breathing is restored. In suffocation from coal gas, smoke, or other cause, arti- ficial respiration, as above, may restore animation. CHOKING FROM SOMETHING IN THE THROAT, When any one has something fast in the throat and cannot breathe, place the sufferer on a chair, leaning forward, or on the side, inclining a little toward the face, and whoever present has the longest fingers should introduce the two fore ones of one hand back as far as possible into the throat, and the obstruction may be hooked out. Or possibly the irritation of the fingers in the throat may cause an effort to vomit, which may clear the throat. If this fails, lay the patient on the belly on a lounge, bench, or table, with the face projecting past one end of it, raising the other end a little. Now have firm pressure made with hands on the back and sides of the belly, to prevent the descent of the dia- phragm, and make quick, jerking, hard pressure, or forcible blows, with the flat hand, on the sides of the chest, over the lower ribs, when air may be forced out of the lungs and the obstruction in the throat dislodged. In case of a piece of coin or such hard substance lodged in the throat, when breathing is not entirely sus- pended, when the body is in this last position and a finger is pressed far back upon the tongue the obstruction may drop out. In the case of a child, it may be held up by the feet. hi: ^ ! QUESTIONS. PART I.— ANATOMY AND PHYSIOLOGY. Paok. 7. Chapter I. — Introductory. — Into what t^ivo great classes may all things be divided ? Why are living things called organic ? To which class does your own body belong ? Of which class is it built up ? 8. What are simple elements ? How many j;o to form all living bodies ? What are the four principal ones ? What do oxygen and nitrogen united form ? What, oxygen and hydrogen ? What common substance is nearly pure carbon ? Are elements usually found in a separate state ? What about the force which unites them ? And the new substance thus formed ? 9. What element is most inclined to unite with others ? How is it so great a variety of substances are formed by a few elements ? How is it that we can separate the elements in a compound ? What two things are generated or given off when elements unite ? 10. Name some organic compounds. Name something which is mostly caseine ; and something which is mostly albumen. What is the simplest organic form known ? Can you describe a cell ? ,11. In what do cells originate ? How do they multiply ? Where are thej' found ? What is known about the nature of life ? 12. What are the necessaries or essentials of life? To what branch jf study does the consideration of these belong ? What cause wear and waste of bodily substance? What dependency has health on the waste matters? What prevents you getting lighter ? What are the three principal substances thrown off as waste ? 13. What gas enters your blood at every breath? W'hat is anatomy? What physiology ? What does hygiene teach ? Chap. II.— Constituents, etc., of the body. — Of what elements are flesh and other soft solids made ? What makes the bones hard ? 14. Name some other elements found in the blood and other parts. What about the water in your body ? Can you mention some properties and uses of the four simple tissues : fibrous tissue, cartilage or gristle, connective and fatty? 15. Name the compound tissues. For what is the skin designed? De- scribe its structure. What does it contain? What is mucous membrane like? What cavities does it line ? 16. What do serous membranes line? What is their function? Can you name the anatomical divisions and cavities of your body ? What two large chambers or cavities are in your trunk ? How is your body made up ? What part is the special organ of the mind? What makes up the framework of the body ? What is the purpose of the flesh ? 17. How are all parts of your body connected together? What parts are called organs of animal life ? Why ? What of the other organs ? 18. What are the three chief functions of the vegetative organs ? How are these organs of supply and waste brought under the influence of the will ? Chap. HI. — Nervous System. — Through what syst«.;- is the mind made manifest, or revealed .' 19. What are the two forms of nerve matter like ? Which simply conveys nerve influence ? What are the two great centres of nervous influence or port'er? From what parts do the nerves proper seem to start ? What are the t"o systems of nerves called ? 154 QUESTIONS. classes may all To which class living bodies? nitrogen united stance is nearly ; ? What about rmed ? How is it so How is it that gs are generated which is mostly is the simplest Where are Ihej what branch jf wear and waste : waste matters? ncipal substances lat is anatomy? what elements hard? ler parts. What irties and uses of ectiveand fatty? designed ? De- membrane like? :tion? Can you What two large lade up ? What le framework of What parts are ans? ans ? How are of the will ? s the mind made simply conveys ous influence or What are the I5S Name the three parts 20. Say all you can about the sympathetic system. of which the brain consists. 21. What are between the brain and the bones of the cranium ? What are the convolutions ? What is the medulla like ? Where does the cord lie ? How do nerves divide ? How many sorts of nerve fibres are there in nerves ? 22. Where do the sensory nerve fibres end ? Where the motor fibres ? What do they respectively convey ? To what parts do the 12 pairs of nerves from the brain extend ? And to what parts those from the cord ? Do nerves ever act independently of mind ? What are the functions of the nervous sys- tem ? What is the sptcial work of the nerves proper ? 23. When anything touches your foot how do you know it ? When you WILL to raise your leg or arm, where does the first act or change take place ? If the nerve supplying the limb were cut across, what would be the effect ? 24. What are the functions of the spinal cord ? If the cord were injured or severed in the neck might you live on ? In what state would you be ? To have feeling in, or move at will, any part, what must it have nervous connec- tion with ? 2$. What are reflex or involuntary actions ? Have they anything to do with walking, or grasping anything ? How ? 26. When you repeat an action very often, what does it become ? What is the centre of breathing and swallowing? With what parts are the thoughts, ideas, and memory closely connected ? What proof of this ? 27. Chap. IV. — Bones and Joints. — What is bone? Whose bones are most easily broken ? Why ? What of the structure of bone ? its canals ? 28. Where, and what, is the marrow ? What happens when the thin mem- brane closely covering bones is destroyed ? Why does the bone die ? What is the bony framework called ? 29. Where are the frontal bones ? The nasal bones ? Which jaw-bone is movable ? For what is the large round opening in the skull ? For what the smaller ones? Is the spine formed of one piece? What lies in its canal? To what are the ribs fastened ? Which is your shoulder-blade ? 30. How many buiics in your arm ? and forearm ? In your thigh ? and leg ? What are the three functioris of bones ? What is a lever ? 31. In the action of the bony levers, where usually is the fulcrum ? What constitutes the power ? What the weight ? How many kinds of levers are iHere ? Give examples of each kind. 32. When two bones are joined together, what is formed ? What about the tissues of movable joints ? What movements do joints admit of? 33. What movements take place in hinge-joints? Give examples. What in Imll-and -socket joints ? Give examples. What about pivot joints ? 34. Chap. V.— Muscles. — What are the muscles? What about muscle fibres ? blood-vessels and nervv^s ? 35. To whai are muscles .isi ened ? What and where are tendons ? What is their use? Where can you feel any of the tendons? About how many muscles have you ? Are there any between your ribs ? Any covering the abdomen ? Do the fibres of these all pass in one direction ? What sort of muscle separates the chest from the abdomen ? 36. What is the special use of muscles ? What other functions have they ? How do they produce motion ? What is muscular contractility ? 37. What muscle bends your arm at the elbow ? What sort of lever is then represented ? What represents the weight ? How is the shortening of muscle caused ? When a nerve supplying a muscle is cut, can you use the W3 •I- IS6 QUESTIONS. muscle ? Upon what do most muscles act ? Give examples of the different sorts of levers. 38. What about loss of power in the arrangement of muscles ? What mus- cle is opposed to the biceps ? When two opposed muscles act together what is the effect ? Is any muscular action required in standing ? 39. What is said about easy and graceful attitudes ? What will cause mus- cles to increase in size, firmness, and strength ? Have quality of fibre and nerve power anything to do with muscular strength ? Chap. VI. — Sensation. — What is sensation ? Where may sensations arise ? What about common sensations ? 40. What are the five special sensations ? What parts are assigned to these? How are impressions conveyed from these to the brain? In what particular points does the sense of touch arise ? How does this sense aid the sense of seeing ? Describe a papillae. How learn the sensibility of a part ? 41. What parts are regarded as the organs of touch ? What peculiarities on these parts? What of the sense of temperature? Wheie is the sense of taste ? What about the papillae of the tongue ? ' 42. Name one condition of taste. May taste be altered by habit ? Is taste connected with smell ? Where is the sense of smell ? 43. Where is the Schneiderian membrane? What is there peculiar about it? Where do the nerves of smell end? Where is the sense of smell most delicate ? In what does this sense aid you ? May it be improved ? Are the nostrils a good respirator to breathe through ? What are the different parts of the ear ? 44. What is the pinna ? And auditory canal ? What membrane closes the canal within ? What does the middle ear contain ? Where is the Eustachian tube ? What are the parts of the inner ear ? 45. What is within the bony labyrinth ? What are the otoliths ? Where do the filaments of the two nerves of hearing end ? What are the essential parts of the organ of hearing ? Explain the nature of sound. 46. How is the sensation of sound produced ? What is the office of the pinna ? How is sound conveyed to the drum and inner ear ? 47. How many membranes form the ball of the eye ? Which is thick and strong? Of what does the inner one chiefly consist? What color is the middle one? What are the contents of this ball or chamber? What is a lens ? Where and what is the iris? What is there peculiar as to its color? What is the circular opening in it ? Why does the pupil always seem black i What is the effect of light upon the pupil ? What is light supposed to be ? 48. What is a ray of light ? What three things may happen to rays when they meet with different substances ? What is a reflector ? What do ray.o pass through ? What colored substances take in rays ? What colored sub- stances reflect most rays ? What rays enter the eye? What becomes of them there ? What is produced ? How is the nature of this picture communicated to the mind ? 49. What is the use of the lens and fluids of your eye ? What use have the muscles on the outside of the eye-ball ? What parts protect the eye ? What is the conjunctiva ? What does the lachrymal gland near the outer corner of the eye produce ? How do tears get into the nostril ?. What of the eyebrows ? 50. Chap. VII. — Blood and the Circulation. — Having bones, flesh, nerves, brain, and organs of sense, all clothed in skin, could you move or think without something more ? What is this something called ? What gives rise to force or strength ? What is it that flows about all over your body and QUESTIONS. 157 »f the dififerent ? What nius- together what vill cause mus- ty of fibre and nay sensations ire assigned to ain? In what s sense aid the ty of a part ? at peculiarities is the sense of labit ? Is taste peculiar about of smell most •ved ? Are the ifferent parts of irane closes the the Eustachian »liths ? Where the essential le office of the ch is thick and jr is the middle lens? Where What is the What is the to rays when What do ray.-5 at colored sub- comes of them communicated It use have the e eye ? What outer corner of the eyebrows ? J bones, flesh, you move or ? What gives your body and carries with it heat and force, and nutrient matter for the tissues ? How do you know j cur tissues are full of blood ? 51. Jiioes blood contain many substances? What float in it? What are the corpuscles like ? Are the same ones in the blood all the time ? 52. What happens to blood soon after it is taken from a living body ? When you stir fresh blood with twigs, what do you get ? What, when you wash this with water ? After you have removed the fibrine, will that which is lefc form a clot ? What is the liquid in which the clot at last floats ? How is the clot formed ? 53. What is the clot ? What does serum contain ? How would you show that serum contains albumen ? In what does the blood flow ? 54. What are the minutest blood vessels called ? Is your body very full of them ? Can the blood be seen flowing in these in a thin membrane ? Does blood supply all the wants of the tissues ? 55. Does the blood, besides supplying nutriment, carry away anything from the tissues? Can organs perform their function without blood flowing in them? What is meant by osmosis ? 56. How do the nutrient and waste matters get through the thin walls of the minute blood-vessels ? What two sets of vessels carry the blood to and fro between the capillaries and the heart ? What are the arteries like ? Which carries the blood from the heart ? What is the greater circulation? To what parts is the lesser confined ? 57. W^hat is the heart like ? Put your hand over your heart. How many chambers has it ? Which rt-e its ventricles? What membrane covers it? 58. What form the bulk of the heart? What openings are there in the heart ? Where are the tricuspid valves ? Where the bicuspid ? Where does the blood flow to out of the ventricles ? 59. What valves prevent blood flowing back from the arteries ? Where -re they ? What are the two great arterial trunks ? To what parts does the I ^rta send branches ? To what parts the pulmonary artery ? Into what do the final branches empty ? 60. Where can you feel ihe throb of the large divisions of the aorta ? What course do they take next ? At what places can you feel the main artery of your arm ? Where, the carotids and temporal ? Where do the veins com- mence ? In what do they end ? 61. What prevents blctod in the veins flowing backward ? What is the course of tlie deep veins ? Can you see the course of the superficial veins anywhere ? What mt ^s arterial blood brighter than venous blood ? 62. Where is there i- .aird set of capillaries ? From what organs does the blood flow into these ? Give the course of the blood from Fig. 36. 63. In which vessels does the blood move fastest ? In which the slowest ? What forces move the blood ? In what is the chief force ? Which ventricle has the hardest work to do ? What causes the beat of the heart ? Explain the action of the arteries. 64. Do arteries help in moving the blood on ? What helps to move it in the capillaries? What in the veins? What regulates the flow? Does your heart ever rest ? 65. Can you explain how the contractions of your heart are brought about ? W^hat causes the pulse ? How many times does the heart beat in a minute in infancy ? in childhood ? and after the age of twenty ? 66. Chap. VIII.— Respiration and Heat.— What is the function of respiration ? What gases do animals take in and give out ? Through what 158 QUESTIONS. organs does oxygen get into your blood ? What about the membrane form- ing the lung ? Describe the structure of a lung. 67. Why are the lungs called 'lights' ? Describe the trachea and bronchial tubes, Fig. 37. What form the walls of the chest ? How is the breadth of the chest, from side to side and from front to back, increased ? What action has the muscle which forms the floor of your chest ? Is your chest air-tight ? 68. Why does a bladder flretch when you blow into it ? Explain how and why iir enters your lungs. If air gets in between the walls of the chest and the lungs what happens ? What prevents friction between the walls of the chest and the lungs ? Explain the acts of breathing. Figs. 39, 40. By which muscles chiefly are the ribs raised ? By which drawn down again ? How many times do you breathe in a minute ? 69. What gives rise to the breathing movements ? Are your lungs filled and emptied at every breath ? About how much is pumped in and out ? 70. Is the air you expel by expiration the same you had just drawn in by inspiration ? Explain how this is. How long a time does it take for all your blood to flow through your lungs ? What changes take place in the blood ? What is the difference between expired and ordinary air? How much oxygen do you consume every day ? How much water and carbonic acid give off" ? 71. When do you use most oxygen and give off most waste stuffs? What elements unite when oil burns in the lamp? On what unions does the warmth of your body depend ? What are the products ? Does all the oxygen you breathe unite with carbon and hydrogen ? 72. Is heat generated in all parts of your body ? Where most ? How is it equalized and distributed ? What regulates and keeps it within healthy limits ? What is 'he temperature of your body ? 73. What relation has heat to force or power in the body ? Where and what is the larynx ? Where and what are the vocal cords ? How is voice produced with these ? What is speech ? 74. Chap. IX. — Digestion and Absorption. — What nourishes the blood? What must foods contain ? What process must they under{;o ? What two classes of organs are provided for this purpose ? What is meant by di- gestion ? 75. Under what four heads may foods be classified? Why are the proteids also called nitrogenous ? What chief purpose do they accomplish ? Do fats and amyloids contain nitrogen ? What is their chief purpose ? Name some proteid substances ; some amyloids. To what class do water and salts belong? Do ordinary foods contain more than one of these food principles ? What are the parts of the alimentary canal ? 76. Describe the mouth and teeth. Where are the uvula and tonsils? What are the openings in the pharynx? What leads from it into the stomach? Where is the stomach ? Describe it. 77. What part of the canal comes next ? What two tubes open into this ? How long is the small intestine? Into what does it open? How ini.ny layers or coats form the walls of the digestive canal? What does the inner coat resemble? Why is it red and moist? Which coat is muscular? What is its function? What are the pecu'.iarities and uses of the serous coat ? 78. Where and what are villi (Fig. 45) ? and lacteal tubes ? What glands are connected with digestion ? What is the duct ? What is the secretion of a gland ? Whence is it obtained ? 79. Where are the three pairs of salivary glands ? Where is the pancreas ? What are gastric follicles ? Which is the largest gland in the body ? Where tiembrane form- ea and bronchial s the breadth of ? What action chest air-tight ? Cxplain how and )f the chest and the walls of the I 40. By which II again ? How our lungs filled 1 and out ? ust drawn in by :ake for all your ce in the blood ? iw much oxygen icid give off ? e stuffs ? What loes the warmth the oxygen you ost ? How is it healthy limits ? ■ ? Where and How is voice nourishes the nderi;o ? What is meant by di- ire the proteids )lish ? Do fats Name some d salts belong? ciples ? What tonsils? What the stomach? )pen into this ? w uiiny layers the inner coat ? What is its t? What glands secretion of a the pancreas ? ody ? Where QUESTIONS. 159 is the liver ? Describe its structure ? From what is bile secreted ? How does bile get out of the liver ? To where is it conveyed ? What are the five digestive juices ? What peculiar substance does saliva contain ? 80. What effect has saliva on starch ? What is gastric juice like? W^hat effect has it on meat, milk, etc.? Has pancreatic juice any effect on starch or fats ? What of the intestinal juice ? What action has bile and pancreatic juice? What causes the glands to form and pour out their secretions? 81. Does digestion of any part commence in the n»outh? Explain the act of swallowing. How long is the food retained in the stomach ? How is it mingled with the gastric juice ? What foods are dissolved in the stomach ? Do any parts pass directly from the stomach into the blood ? What is chyme ? What changes take place in it in the duodenum ? What is chyle ? What happens to it as it is moved along in the intestine? 82. What is meant by absorption? Describe the property or process called osmosis. What is said of the way chyle is absorbed by the villi and forced up the lacteal tubes? What are the lymphatics and lymph? 83. In what large tube do nearly all lymphatics join at last? W^hat are lacteals ? Why are they so called ? How is it when no fat is eaten, nor digested? Into what veins are the chyle and lymph emptied? What and where are the lymphatic glands ? What of the function of lymphatics ? 84. Chap. X. — Excretion. -If the waste matters were not removed from your body constantly, what would be the result ? In what forms, chiefly, are the waste matters? What of the water thrown off? What organs throw off the waste ? What are excretions ? 85. What of nails and hairs ? What are the sweat glands and pores of the skin ? What do they excrete ? Of what does perspiration consist ? Is much waste thrown off by the sweat glands ? 86. What is the structure of the kidneys? Do they act an important part in purifying the blood ? PART II.— HYGIENE. 87. Chap. XI. — Introductory.— What is the condition called health ? What is disease ? What are causes of disease ? 88. Name the essentials of life ? With what are most causes of disease connected ? What is said in reference to the connection between waste mat- ters and disease ? What are other causes of disease ? 89. How may we avoid or prevent disease ? Will attention to the laws of health help to cure disease ? W^hat of false ideas regarding disease ? 90. Why do diseases come ? How are they often brought upon us? What is said of the slow action of causes of disease ? Are we always warned by pain of the approach of disease ? 91. Chap. XII. — Air. — Of what does pure air consist ? Can we have good health without it? In what places is air most impure? What furnish the most important impurities ? What are the chief impurities ? 92. What condition of the air is most productive of disease ? What is the most important impurity in breathed air ? What is the nature of this organic poison? What effect has the air from sewers, cesspools, etc., on milk and meat ? To what points does such air tend ? May it be readily detected by the sense of smell ? 93. What about the air of marshes, etc. ? And from cellars? What dis- eases are favored by air from wet, undrained soil ? What are the local effects of the air in steel grinding and shoddy works and mills ? How are they pro- i6o QUESTIONS. duced ? Wh^t is the effect of breathing air from excremental matters ? How does the poisoned air gel into the blood ? What symptoms folloM' ? 94. What do statistics prove to be the most important cause of death ? Can you name instances of speedily fatal effects caused by re-breathir.g breathed air? Does breathing this in small quantities do harm? What may be caused by breathing it even for a few hours a day ? 95. How may the germs of specific contagious diseases get from one per- son to another ? How may the germs be destroyed ? Name some diseases which are caused by breathing air from fecal and other waste matters. 96. What are the two general means for keeping the air pure? What about the water-carriage and dry systems of removal of waste matters ? What is meant by ventilation ? Of what is want of it a most fruitful cause ? What is said in reference to securing it ? 97. What is said of draughts of air ? Can we ventilate without producing perceptible draughts ? How may air be best diffused through a room ? Ex- plain how and by what force air may come into a room. 98. What effect has an open grate fire ? How may a good inlet for fresh air be provided ? How, an o 'let when there is no grate ? What is said of air not being diffused through f le room ? How much fresh air does every one require every hour ? With suk supply would the air in a room be as pure as that outside? How large should an inlet be for each person? What of the outlet ? 99. What amount of cubic space for every individual ? Why so large ? What are the best methods for warming dwellings? How may the objections to stoves be obviated ? What should be the temperature of the air in rooms ? What effects come from living in a very warm room ? 100. When should you go from a hot to a cold room ? What about extra clothing and a respirator? What are disinfectants? and deodorants? What about abundance of fresh air? For what is carbolic acid used ? What burning sulphur ? potassium permanganate ? and ferrous sulphate ? What of dry heat ? loi. Is sunlight a disinfectant? What is said of it in reference to rooms, etc. ? When should you be shaded from it ? What about respirators ? Chap. XHI. — Water. — Do all waters contain foreign matters? What gives to water its agreeable taste and sparkle ? 102. What may good water contain ? What is good water like ? What is said of its solvent powers? and in reference to its flowing over and through the ground ? Whence is all fresh water derived ? 103. Why does rain water feel soft ? When is it purest ? Why ? What is said of its solvent powers ? and of it as a beverage ? Why are spring and well waters hard ? What two important changes does water undergo in the soil ? What of deep well waters ? 104. Why are river and lake waters less pure? What natural processes help to purify them ? What of impure water as a cause of disease ? What is said of mineral impurities, especially lead ? What matters then cause the greatest mischief? What is said of living organisms in water? How may danger from the use of leaden pipes be lessened ? 105. What are the chief sources of organic impurities in water ? How far may they be carried through the soil ? How may a well of water become J isonous? What principal diseases and bodily conditions are caused by the uss; of foul water ? How would you judge as to the purity of water ? ko6. What are the most practical methods for purifying water ? What should be done with water after boiling ? What are the best filtering mate- matters ? How )llow ? e of death ? Can jathir.g breathed t may be caused t from one per- e some diseases matters. re ? What about Iters? What is I cause? What ithout producing h a room ? Ex- d inlet for fresh What is said of r does every one >m be as pure as I ? What of the Why so large? y the objections le air in rooms ? lat about extra orants ? What What burning hat of dry heat ? rence to rooms, pirators ? latters ? What ike ? What is er and through Vhv? What is spring and well rgo in the soil ? tural processes !ase ? What is then cause the ? How may ter ? How far water become caused by the ater ? ■ater ? What filtering mate- QUESTIONS. i6i rials ? What about renewing them ? What about the location and construc- tion of wells ? 107. How may wells and cisterns be ventilated ? What about water for allaying thirst ? Chav. XIV. — Foods. — What is the purpose of food? What must foods contain and be capable of ? 108. Into what four groups are foods divided ? Which are nitrogenous ? Which non-nitrogenous ? To what does this classification relate ? Do foods usually contain more than one of these principles ? What as to the propor- tions ? What can you say about albumen, fibrine, gluten, caseine ? 109. What is the chief purpose of the proteids ? What of the fats and amyloids ? What are sago, tapioca, potatoes, and rice chiefly ? What are the mineral foods ? What should a perfect diet contain ? Which group alone would support life the longest ? 1 10. Why are starches, sugars and fats essential to health ? What about the necerary proportions of each group ? What leads to errors in diet ? 111. What are the animal foods? What of the composition and digestibility of flesh ? What method of feeding animals secures the best flesh ? What are the marks of good flesh ? What of bad ? What is said of pork ? What of poultry and fish ? What of the digestibility of lobsters, heart, tongue, liver, and kidneys ? 112. What of salted and cured meats? Of what do eggs chiefly consist? What of their nourishing properties and digestibility? How are they best cooked ? Is milk a perfect food ? Does the food of the cow affect the milk ? What are the chief constituents of milk ? And their proportions ? What are the properties of good milk ? What about milk from old or diseased cows ? Where and how should milk be kept? Why? Is milk much more than a drink? 113. What is butter ? What of rancid, bad smelling butter? What effect has heat on butter and fats? What parts of milk is cheese ? For whom is it best suited? Which is the most valuable bread-producing grain? Is wheat a perfect food? What proportion of solid matter does it contain ? What are its constituents? 1 14. What of wheaten meal and cracked wheat ? Name the properties of good flour and dough ? What of old flour ? To what is it liable ? What grains are next to wheat in nutritive value ? What about corn, peas and beans ? For what are fruits chiefly valued ? 115. Name some of the most valuable fruits. What of unripe fruits? Which is the most valuable succulent vegetable ? What about other succulent vegetables ? What is said of liquid foods ? 116. What, next to water, are the most natural drinks? Are tea and eoflee essential to health ? How are they adulterated ? What of the color of teas ? What of chocolate and cocoa ? 117. What is said of sugar? and candies and confectionary? What of pre- serves and canned fruits ? Is salt essential ? What of vinegar, pickles, sauces and spices? What is the purpose of cooker;'' What are two important points in regard to it ? 1 18. How does boiling affect meat ? How should you conduct the process? Why ? What of making soups and broths ? How about boiling vegetables ? What of roasting ? broiling? stewing? and frying? 119. What is said of fermented bread, and baking it? What of aerated bread ? and new bread ? What about puddings, pastry, etc. ? When is the best time to eat ? l62 QUESTIONS. 1 20. What is said of regularity in eating ? How long a time should elapse between each meal ? What is said of the breakfast ? What of the mid>day meal and dinner? How much time between the last meal and bed time? What of the amount of food necessary ? Is all that is eaten digested ? 121. By what is the demand for food increased ? What is said of eating too much ? How does it produce disease ? 122. How may you know when you have eaten enough ? What of change in diet ? What of appetite and taste ? To what does variety of foods tempt ? What of thorough mastication and insalivation ? Of very hot or very cold foods and the teeth ? 123. Whet class of foods do you require most of in cold weather ? What is of much importance in reference to diet and warmer weather and taking less exercise ? What is said of mental and bodily rest before and after a meal ? What is said of the surroundings of the table ? and an occasional fast ? 124. Chap. XV. — Exercise. — Is exercise necessary to health ? If you do not exercise both mind and body, what follows? What are the effects of exercise and use of the bodily organs ? 125. What of mental exercise and memory? What about too little exercise? 126. What will too much exercise or over- work produce ? What is said of mental over-work and keeping your attention on a subject of study ? What of unequal or incomplete exercise ? 127. What is the object of hygienic exercise ? What is it necessary to bring into active use every day ? What about those who work hard ? May will- power be increased by exercise ? Do diseases arise through want of will-power? 128. What is said of regularity and method in taking exercise ? How should exercise always be commenced? and why? Is this especially necessary at any particular time ? Why should exercise be taken in the open air ? 129. What about taking exercise in sunshine? When should you not take active exercise ? What about engaging the mind in the exercise ? What is said of gardening ? and gymnastics ? 130. What of walking and skating? and running and leaping? cricket and base-ball ? dancing and rowing ? What of the amount of exercise and in reference to fatigue ? What about taking stimulants when tired ? 131. Chap. XVI. — Rest and Sleep. — What must follow work and exer- cise ? For what purpose ? In what position is rest most perfect ? Why ? 132. What effects are certain to follow want of sufficient sleep ? What amount of sleep is necessary ? Who require most sleep ? How would you learn how much sleep you need ? 133. Why is night the best time to sleep ? What about sleep before mid- night ? What is said about rising early ? and morning air ? What about the sleeping room and night air ? 134. Do beds receive much waste matters from the body ? What is said in reference to them? and to feather beds? hair, wool, and wire mattresses? and pillows ? What is best for bed clothing? Why? What should be done with the clothing ? What should you do on going to bed ? 135. Chap. XVII. — Clothing. — Does clothing supply heat? Why does linen feel colder than woollen ? What clothes, then, are warmest ? Explain why cotton and linen feel colder than woollen when wet. Which will hold most moisture ? 136. What materials are used for clothing? What is said of cotton when somewhat loosely made ? What is the best material for clothing ? What of linen? silk? and furs? What of impervious clothing? What is best for wear- QUESTIONS. 163 le should elapse of the mid-day and bed time? jested ? s said of eating Vhat of change jf foods tempt ? )t or very cold jather ? What her and taking id after a meal ? al fast ? ilth ? If you do e the effects ot ) little exercise? What is said of study ? What cessary to bring rd ? May will- t of will-power? xercise ? How cially necessary lopen air ? Id you not take cise ? What is J ? cricket and xercise and in I? ivork and exer- ct? Why? sleep ? What ow would you !p before mid- What about Vhat is said in attresses? and be done with ? Why does st ? Explain lich will hold f cotton when g ? What of Jest for wear- ing next the skin ? Give reasons. What is said about wearing the same garment at night that is worn during the day ? 137. Why must under-garments be frequently changed, aired, and washed ? What should you put on after working and perspiring ? Why ? What is the warmest color, usually? Why ? Why is white best for nurses? 138. What two objections to tight clothes ? What is said of tight corsets ? garters, and boots ? What of the quantity of clothing required ? 139. What are the consequences of too little clothing ? What of over- clothing ? and of unequal clothing ? What about the extremities ? Is heavy clothing necessarily warm ? Why can you not work when thickly clothed ? What about clothing after work, or in the evening ? When should changes in the clothing be made ? What of clothing and the weather ? 140. Chap. XVIII.— Bathing.— Why should you often wash the whole surface of your body ? If you do not, what will be the effects upon the blood and the kidneys ? To what are you then more liable ? And what effect upon the regulation of bodily heat ? 141. What about bathing as relates to taking cold ? And to the sensation of touch ? What is the highest safe temperature for the bath ? What usually the lowest ? What would be a hot bath ? What of the temperature when one is exercising in the water ? What effect has cold water on the blood- vessels in the skin ? 142. What should follow ? What in case reaction does not follow? What effects are produced by the warm bath? Is it of much hygienic value? What is said of it as a restorative ? and as retarding the effects of age ? 143. What should be its temperature? How long may one stay in it? What is said of the sponge bath and the hands ? What effects have the cold plunge and shower baths ? What of the vapor bath ? What should follow it ? What is the safest rule in bathing ? 144. Chap. XIX. — Causes of Disease, Sickness and Accidents.— What is said in reference to the best time to bathe ; the digestion of food, and heat of the body ? Name now the chief causes of disease. 145. Whence come the chief impurities in the air ? How do they get into the blood ? How avoid breathing them ? Whence the chief water impurities ? What diseases arise from errors in diet ? To what is one then more liable ? 146. How avoid contagious diseases? Should you have such disease, what means would you use to avoid giving it to others ? 147. Where shoi'ld the sick room be? What about the walls? floor? bed ? ventilation and an open grate fire ? 148. What about bathing the sick ? What should be done with the excre- mental matters ? What about visitors ? whispering ? and disinfectants ? 149. What should you do in case of copious bleeding from wounds ? What in less copious ? What is chiefly to be relied upon in all bleedings ? How recognize bleeding from the lungs ? What would you do ? 150. How extinguish the flames when one's clothes are on fire ? How remove the clothing when the ^kin has been burned ? What would you apply to the burns ? What action is advised when one is in a fit, with dark florid face and lying quiet ? What when there is jerking or throwing about of the limbs ? 151. What is it very important not to do when the face is pale, and breath- ing and pulse imperceptible ? What would you do ? When any one has swallowed an irritant poison what would you give ? What antidotes would you give for the following poisons : strong acids ? potash or ammonia ? arsenic ? 1 64 INDEX. strychnine ? oxalic acid ? tartar emetic or white vitriol ? corrosive sublimate 7 opium or alcohol ? prussic acid ? 152. What are the two great objects in restoring the apparently drowned? How would you proceed in order to restore breathing ? How to promote warmth ? What about the tongue ? 153. What after suffocation from coal gas or smoke? What when one is suffocating from something fast in the throat ? INDEX. Paos. Abdomen 16 Absorption 82 Air, pure, composition of 91 II impurities in 91 tt amount of required 98 II expired 92 H temperature of. 99 Air-cells, of lungs. 66 Albumen 10, 108 Alcohol, a medicine 116 Alimentary canal 75 Amount of food necessary 120 Amyloids 75, 108, 109 An!'*omical divisions of body ... 16 Anatomy, defined 13 Animal foods 1 1 1 II life, organs of. 17 Aorta 59, 60 Appetite 122 Arm 16, 30 Arteries 56, 59, 60 Arterial blood 61 Articulations 32 Atmospheric air 91 Auricles 57, 58 Back bone or spine 29 Bathing and health 140 II cold 141 Bath, warm 142 Beans and peas 1 14 Beat of heart 63 Bed and bed-clothing 134 Bed-room 133 Biceps' muscle 36, 37 Bile . 80 Black clothes 137 Bladder, urinary 86 Bleeding, how arrested 149 Paob. Blood, and its circulation 49 II arterial ami venous 61 II a complex fluid 50 11 a circulating market. ... 54 II clot 52 II composition of 53 II corpuscles 51 II movements of 63, 64 II purification of 86 Boiling foods 118 Bone, composition of 27 II structure of. 27 Bones, functions of 30 II number of in body 28 II of head and trunk 29 II ot arm and leg 30 Br^iln, and parts of 20 II convolutions of. 26 II functions of 26 II greater and lesser 21 Bread, fermented & unfermented 119 Breast bone 29 Breathing, movements of. 68 Breathed air 70 Broiling 118 Bronchial tubes 66, 67 Burns, management of. 150 Butter 113 Capillaries, and circulation in. . . 54 Carbonic acid in blood 61 II in breathed air. 70, 92 II in water 103 Cartilage , 14 Caseine 10, 75, 109 Cells, simple 10, 11 Cellars, air in 93 Cheese 113 Chest or thorax 16, 67, 68 sive sublimate 7 ently drowned? low to promote lat when one is Paob. tion 49 inous 6i d . . , so narket .... 54 ^ 53 51 63, 64 86 118 27 27 30 ody 28 mk 29 30 20 26 26 er 21 ifermented 119 29 of. 68 70 118 ....66, 67 150 ■ 113 tion in. . . 54 61 edair.70, 92 103 14 10, 75. »o9 .... 10, II 93 i'3 16, 67, 68 INDEX. 165 Paok. Chest, expansion of. 126 Chyle 81 II absorption of 82, 83 Chyme, absorption of. 81 Circumduction 32, 33 Circulation of blood 5^ II course of 62 11 greater and lesser. . . 5^ i> in capillaries 54 Cisterns 107 Clothing and health 135 II amount of required .... 138 II color of. 137 II impervious 136 II manner of wearing. .. . 137 II materials used for 136 II must be loose 1 38 II properties of 1 35 II sudden changes in 139 Chocolate and cocoa 116 Cochlea 44, 46 Coffee and tea 116 Compression in bleeding 149 Colon, or large intestine 77 Condiments or seasonings 117 Conjunctiva 49 Connective tissue 14 Convolutions of brain 21, 26 Cooking foods 117 II meats & vegetables. 118, 119 Cornea 46 Corpuscles of blood 51 Cotton clothing 136 Cranial nerves 22 Cranio-spinal system 19 Cranium 16 Dancing as exercise 130 Deodorizers 100 Diaphragm 67 Digestion 74 II glands connected with. 78 Digestive apparatus 75 II fluids 79 Disease 87 It causes of 88 II causes of, slow in action.. 90 II false ideas regarding.... 89 Draughts of air 97 Drum, of ear 44, 46 Ducts, of glands 78 Ductless glands 86 Duodenum 77 Paoi. Dysentery, cause of. 105 Ear, parts of. 43. 44. 45 II functions of 46 Early rising, on 133 Eating food slowly 122 II best time (or 119 r rest before and after 123 II too much 121 Ei^gs, about, as food 112 Elbow joint 33 Elements, simple 8 Epiglottis 73, 76 Epithelium of mucous mem. .15, 77 Erect posture in walking, etc. . . 130 Essentials of health &iife. 12, 87, 88 Eustachian tube 44. Excremental matter , 96 Excretion and secretion 84 Excretions, waste matters 84 Exercise and health 124 II amount of required. ... 130 II effects of. 124 II forms of 129 II too little 125 II too much 126 II mental 125 II objects of 127 II unequal or incomplete . 126 II regularity in 128 II should engage the mind 129 II should be commenced moderately 128 II should be in open air. . 128 II demands more food.... 122 Exhaustion from exercise 130 Expiration and inspiration 68 Extension, of limbs 32 Eye, parts of. 46, 47 II brows, lids, and lashes.. . . 49 Fats 75, 80, 81, 108, 109 II effects of heat on 113 Fatty tissue 15 Fibrine 10, 52, 75, 108 Fibrous tissue 14 Filte' ind filtering water. 106 Flesh .*nd muscle 34 II as food m Flexion, of limbs 32 Flour, wheaten 114 Food and health 107 Foods, classification of.. 75, 108, IC9 II animal m I i66 INDEX. Paob. Foods, liquid 1 15 M vegetable < 113 II amount of required 120 II preparing and cooking. . 117 Fruits, as food 114 II juices of, as drink 116 Frying foods 119 Gallbladder 79 Ganglions, or nerve centres .... 19 Gastric follicles 79 II juice 80 Gelatine 10, 75, 109 Glands of digestion . . 74, 75, 78, 79 II lymphatic 83 II of skin 84, 85 II salivary 78 Glottis 73, 76 Gluten 108, 1 14 Gullet, or pharynx 76 Gymnastics 129 Hairs 85 Head, bones of 29 Hearing, sense of. 43 Heart 57 11 parts of 58, 59 M beat of 63 II action of. 64 Heat, animal, how generated. . . 71 II how distributed & regulated 72 II and force 73 Hepatic duct and vessels 79 Hinge joint 33 Hip joint 33 Hunger and thirst 80 Hygiene 12, 13 II value of 89 Indian corn 1 14 Injuries, accidental 149, 150 Inorganic bodies 7 Insalivation 122 Intercostal muscles 35» 67 Intestines, small and large 77 Involuntary actions 24, 25 Iris 47 Inspiration and expiration 68 Jaws, upper and lower 29, 76 Joints, the 32, 33 Jumping or leaping 130 Kidnevs and their secretion .... 86 Knee joint 33 Labyrinth 45 Lachrymal gland 49 Paoi Lacteals 78, 83 Lake and river waters 104 Larynx 73 Lead poisoning 104 Legs, bones o(. 30 Levers, the three kinds of. . .30, 31 Life, concerning 11 II essentials of 12, 87 Ligaments, of joints 32 Light 47 Linen, for clothing 135, 136 Lips 76 Liver, its structure and vessels.. 79 II circulation in, etc 62 Living, the, and not living 7 Lungs, the blood in 70 II circulation in 56, 63 11 quantity of air in 69 II as excretory organs . . 84, 86 II air from 92 Lymph and lymphatics 82, 83 Marrow 28 Mastication 80, 81, 122 Meats, flesh in II boiling, roasting, etc.... 1 18 Medulla, and its function .. . .21, 26 Membranes, mucous & serous. 15, 16 Milk, as food 108, 1 12 Mind and matter 18 11 nerve mattei independent of 22 II and sensation 23, 39, 40 II over- work of 126 Mineral foods 75, 109 Mixed diet 109 Molar teeth 76 Motion, organs of. 34 II animal, how produced. . 36 Motor nerve fibres 22 Mouth 16, 76 Mucous membrane 15, 77 Muscles, flesh, structure of. ... . 34 •I attachm'ts& functions of 36 II number of in body. ... 35 II of eye 49 Muscular contractility 36 II fibres 34 II effort, in standing. ... 38 II exercise 124 Mutton Ill Nails, of fingers and toes: 85 Nasal cavities 16 Nerve centres 19 INDEX. 167 Paoi s 104 73 104 30 ids of. •.30, 31 II la, 87 32 47 i35» 136 76 nd vessels . . 79 etc 62 living 7 70 56, 63 ir in 69 organs . . 84, 86 92 cs 82, 83 28 ....80, 81, 122 Ill ng, etc. . .. 118 tion....2i, 26 k serous. 1 5, 16 . ..108, 112 18 ependentof 22 •••23, 39, 40 126 75. 109 109 76 34 reduced . . 36 22 16, 76 15. 77 re of. 34 net ions of 36 body 35 49 36 34 ding.... 38 , 124 Ill les; 85 16 19 Paoi. Nerve matter and mind 22 Nerves, cranial and spinal 22 II functions of. 22 II motor and sensory 22 II structure of 19 Nervous influence 22, 23 II ti.ssue 19 Nitrogen 8, 13, 91 Nitrogenous foo Oxygen 8, 9, 91 II amount of consumed .... 70 « in blood 61 II in water loi Ozone, nature's disinfectant. .91, 100 Palate 41 Pancreas, or sweet-bread 79 Pancreatic juice 80 Papillae of taste 41, 42 II of touch 40, 41 Parotid gland 78 Parsnip, as food 115 Pastry, pancakes, etc 119 Peas and beans 114 Pepsin 80 Pericardium 57 Perspiration, insensible and sen- sible 85 11 amount of 85 II air vitiated by.. . . 92 II and bodily heat. . . 72 Pharynx, or throat 76 Phosphorus and phosphates.. 13, 14 11 in nerve matter .... 19 Physiology defined * . 13 Pinna, of ear 43, 44 II Paoi. Pivot-joint 33, 3 Pleura (of lungs) 6 Poisoning, accidents from 151 Potato, the, as food 115 Poultry, as fo( d iii Proteid foods 75, 108, 109 Puddings, as food 1 19 Pulmonary artery 59, 60 M circulation 56 II veins 61 Pulse, the 65 Pupil, of eye 47 Quality of sounds 46 Quantity of food required 120 Radish, the, as food 115 Rain water 102 Reflection of light 48 Reflex action 25 II artificial or acquired 26 Respiration explained 65, 66 Rest, importance of 1 31 II the most perfect 131 Ribs, arrangement of 29 II movements of, in breath'g67, 68 Rice, as food 114 River and lake waters 104 Roasting meats 108 Rotation of limb 33 Rowing and running 130 Rye, as food 1 14 Saliva in digestion 79, 80 Salivary glands 78, 79 Salt, table, as food 117 Salts in the blood 53 Salted and cured meats 112 Sap in plants $0, 82 Secretion and excretion 84 Secretion of glands 78 Semi-circular canals of ear 44 Semi-lunar valves 59 Sensation 23 II common and special . . 39 II of resistance 40 Senses, the five special 40 Serous membrane 16 II of heart 57 II lining chest 68 M of alimentary canal 77 Serum, of blood ..... 53 Sewers, air from 92 Shoulder-blade 29 Shoulder-joint 33 t68 INDEX. ... I I Paok. Sick room, the 145 Sight, sense of : .... 46 Silk as clothing 136 Skating as exercise 130 Skeleton, number of bones in. . . 28 Skin, glands af, etc 15, 85 Skull, openings in, etc 29 Sleep and rest 131 II amount of required 132 II best time for 133 II effects of want of 132 Sleeping-room 133 Small intestine 77 Smell, sense of 42, 43 Soft water 103 Solvent powers of water 102 Sound, nature of. 45 Soup, as food 115 II and broth, making 118 Speech, how produced 73 Spices, effects of, in food 117 Spine, bones of 29 Spinal cord 21 II II functions of 24 11 nerves 22 Spleen 86 Starch, as food 75, 109, I lO II digestion of, in mouth & stomach 80 Stationary air, in lungs 69 Stomach, 76, glands of 79 II food and digestion in.. 81 Stoves, for warming dwellings. . 99 Sublingual & submaxillary glands 79 Sugar as a condiment 117 II as food, etc 79, 109 II conversion of starch into.. 80 Sulphur, in body 13 Sunlight, its importance.. .. loi, 129 Swallowing, food 81 Sweat glands and sweat 85 II quantity of 85 Sympathetic system of nerves. . . 20 Synovial membranes & synovia.. 32 Taste, sense of. 41 II conditions of 42 II modified by habit 42 Tea and coffee, as a drink 116 Tears, from lachrymal gland ... 49 Teeth, pe nanent and temporary 76 !• care of 122, 124 Paok. Temperature of bodj/, how regu- lated 72 Temporal artery 60 Tendons, their form and uses . . 35 Thirst and hunger 80 Thorax, or chest 16, 67 Thoracic duct 83 Thoughts, instrument of, etc. 17, 26 Tidal air, in lungs 69 Tight clothing 138 Tissues, formation from cells. 10, 1 1 II of body described. . . 14, 15 Tomatoes, as food 115 Tongue and taste 41, 42 Tonsil 76 Touch, sense of 40, 41 Trachea, or wind-pipe 67 Tricuspid valve 58 Turnip, the, as food 115 Tympanic membrane 44 Urea, 12, and ureter 86 Urinary bladder and urine 86 Uvula 76 Valves of heart 58, 59 II of veins ul Vegetable foods 113, 1 15 Vegetative life, organs of 17 Veins, and venous blood. 56, 60, 61 Vena cava, superior & in ferior .60, 6 1 Ventilation 96, 97, 98, 123, 129 II of bed-rooms 133 II of sick rooms 147 Ventricles of heart 57 II contraction of. 58 Vertebra (of spine) 20 Vestibule, of ear 44 Villi, structure of 77, 78 II and chyle 81, 83 Vocal cords and voice 73 V.^alking as exercise 130 Warming rooms, methods of.. . . 99 Warm bathing 142 Wells, structure and location of. 106 II managem't & ventilat'n of 107 Wheat as food 113 Wheaten flour 1 14 Wiud-pipe, or trachea 57, 67 Woolen clothing 135, 136 II under-clothing 136 II after perspiring 137 Wounds, to arrest bleeding from 149 Paob. how regu- 72 60 kd uses . . 35 80 16, 67 • 83 3f, etc. 17, 26 69 138 n cells. 10, 1 1 bed... 14, IS "5 41. 42 76 40. 41 67 58 "S 44 86 rine 86 76 58, 59 01 "3. "5 of 17 Dd.56, 60, 61 nferior.6o, 61 , 98, 123, 129 »s 133 as 147 57 of. 58 20 44 77, 78 81, 83 73 130 lodsof.... 99 142 ocation of. 106 sntilat'n of 107 113 114 57. 67 i35» 136 ; 136 g 137 eding from 149