COLUMBIA LIBRARIES OFFSITE HEALTH SCIENCES STANDARD RA431 D74 HX64074013 Good health, how to HOWIOKEEF • r*j*n^5 w>i>:>5«wr'««B3»M»»»! \ r t '• H * D O 1 Columbia Winibtv^itp in tJeCitp olMtix^ |?ork College of S^^p^itian^ anb ^urseon2( l^titxmtt Hiijrarp Digitized by the Internet Arcinive in 2010 with funding from Open Knowledge Commons http://www.archive.org/details/goodhealthhowtogOOdoty GOOD HEALTH GOOD HEALTH HOW TO GET IT AND HOW TO KEEP IT BY ALVAH H. DOTY, M.D. AUTHOR OF "THE PREVENTION OF INFECTIOUS DISEASES," "THE MOSQUITO,' "A MANUAL OF INSTRUCTION IN THE PRINCIPLES OF PROMPT AID TO THE INJURED," ETC. ILLUSTRATED D. APPLETON AND COMPANY NEW YORK LONDON 1917 Copyright, 1917, by D. APPLETON AND COMPANY TO MY FRIEND DR. T. MITCHELL PRUDDEN A TRIBUTE TO MANY YEARS OF PLEASANT PERSONAL AND PROFESSIONAL ASSOCIATION PREFACE Years ago it was believed that matters relating to the preservation of health and the prevention of disease should be left in the hands of physicians, and little effort was made by the pubhc in aid of this important work. Now we know that the health of a community depends chiefly upon the exertion of its individual members in maintaining not only their own well-being, but also that of their neighbor. This newer conception has recently led to a stimulation of interest in this subject, and societies are being organized to bring about personal cooperation in carrying out the laws of hygiene and sanitation. It is essential that the public should become familiar with recent advances which have been made along these lines, for many of the older theories regarding the care and protection of the body, and the means by which diseases are transmitted, have been proved to be erroneous. It is an extremely difficult task for the medical profession, as well as health departments and other public agencies, to attempt to combat physical inefSciency, ill health, and disease without the cooperation of those for whom their efforts are so generously expended. There should be not a mere passive acquiescence in following the teaching of sanitarians or in complying with health ordinances, but an intelligent appre- ciation of the fundamental principles which animate them and a definite sense of responsibility in maintaining bodily health for both individual and social ends. The terms "hygiene" and "sanitation" are very much alike in their meaning and are commonly used interchangeably. By vii viii PREFACE way of clearer definition, it may be said that hygiene refers more particularly to the care of the body, while sanitation relates rather to the methods of maintaining healthful con- ditions in the environment and covers matters of a more general and extended character; for instance, school sanita- tion, sanitation of the workshop, and municipal sanitation. It is sufficient to know that both refer to the preservation of health and the prevention of disease. It has been the aim of the author to include in this book the essential and salient points in the construction of the body and function of its various parts; also to discuss pub- lic health problems, the maintenance of individual physical well-being, the means by which infectious diseases are trans- mitted and how they may be prevented, the importance of pure air, good water and nourishing food, as well as other matters connected with the subject of hygiene. The author has endeavored to present these in a clear and simple manner, and in a way that will make the application of the information practicable in everyday life and conduct. CONTENTS CHAPTER I PAGE THE STRUCTURE OF THE BODY i The Skeleton — Articulation — ^Joints — Muscles — Blood. CHAPTER II THE VITAL PROCESSES: CIRCULATION, RES- PIRATION, DIGESTION, NERVOUS SYSTEM AND LYMPHATIC SYSTEM 23 Circulation — Blood-vessels — Heart — Respiration — Digestion — Kidneys — Skin — Spleen — Nervous System — ^Lymphatic System. ^ CHAPTER III AIR • . 62 CHAPTER IV WATER 69 Preparation of Food — Distribution of Meals — Re- duction of Weight. CHAPTER V FOOD 86 Nutrition — Diet — Preparation of Food — Distribu- tion of Meals — Reduction of Weight. CHAPTER VI DISPOSAL OF WASTE 122 Sewage — Garbage . ix X CONTENTS CHAPTER VII PAGE VENTILATION 133 CHAPTER VIII / HEATING AND LIGHTING 141 Heating — Lighting. CHAPTER IX PERSONAL HYGIENE 147 Food and Drink — Exercise — Bathing — Teeth — Eyes — Hands and Feet — Sleep — Clothing — Constipation — ^Vacations. CHAPTER X HYGIENE OF THE HOME, SCHOOL AND WORK- SHOP 176 Hygiene of the Home — Hygiene of the School — Hygiene of the Workshop. CHAPTER XI ,, BACTERIA, INFECTIOUS DISEASES AND THE MEANS BY WHICH THEY ARE TRANSMITTED 192 Bacteria — Infectious Diseases and the Means by Which They are Transmitted. CHAPTER XII MOSQUITOES AND FLIES AND THEIR EXTER- MINATION 204 Flies. CHAPTER XIII TUBERCULOSIS 225 CHAPTER XIV DISINFECTANTS AND DEODORANTS .... 235 CONTENTS xi CHAPTER XV PAGE PROMPT AID TO THE INJURED 242 Hemorrhage — Shock — Collapse — Electric Shock — Instructions for Resuscitation — Syncope — Fainting — Apoplexy or Stroke of Paralysis — Epilepsy — Hys- teria — Heat-Stroke, Sun-Stroke, Insolation, Sun Fever, Fever Heat — ^Asphyxiation — Suffocation — Drowning — Burns and Scalds — Frost-Bite — ^Wounds — Fractures — Dislocations — Sprains. INDEX 289 LIST OF ILLUSTRATIONS FIGURE PAGE I. — The skeleton 7 2. — Biceps at rest i6 3. — Biceps contracted 16 4. — Human red blood corpuscles and two white corpuscles . 19 5. — The heart and large blood-vessels ... 29 6. — Diagram showing course of the blood through the heart -30 7. — Showing the relative position of heart and lungs in the cavity of the chest ... 33 8. — The jaws and the teeth 37 9. — Salivary glands 38 10. — The stomach 41 II. — Position of abdominal contents .... 43 12. — Under surface of the liver, showing the gall- bladder and a section of blood-vessels . . 45 13. — The pancreas 46 14. — Vertical section of a kidney .... 48 15. — Section of skin greatly magnified . . . 5^ 16. — The cerebrospinal system of nerves ... 54 17. — Side view of the brain 55 18. — Under surface of brain 56 19. — The mosquito: female 205 20. — Manner in which the eggs of the Culex pipiens, or common house mosquito, are deposited . 207 21. — Eggs of the anopheles 208 22. — The mosquito larva 209 xiii xiv LIST OF ILLUSTRATIONS FIGURE PAGE 23. — Position of larva of common mosquito in ob- taining air 210 24. — Position of anopheles larva in obtaining air . 21a 25. — Pupa. (Smith.) 211 26. — Culex pipiens, or common house mosquito, female 212 2^. — Anopheles, or malarial mosquito, female . . 215 28. — Stegomyia, or yellow fever mosquito, female . 215 29. — Culex sollicitans. Salt water swamp, or striped-legged mosquito 219 30. — Diagram showing the position of the important arteries 244 31. — Artificial respiration: inspiration. Pressure off 255 32. — ^Artificial respiration: expiration. Pressure on 255 GOOD HEALTH GOOD HEALTH CHAPTER I THE STRUCTURE OF THE BODY The owner and master of a human body cannot hope to manage it properly, secure and maintain its usefulness and enjoyment, safeguard it in the diverse struggles of life and occupation, and protect it against sickness and disease without some precise knowledge of its construction and the various things which its organs are made to do. Some glimpses in brief of the structure and func- tion of the body will therefore fittingly introduce a book designed to foster in direct and practical fash- ion the welfare of its readers. THE SKELETON In the study of this subject it is proper that we should begin with an examination of the skeleton, for this constitutes the framework of the body and supports and protects the various organs which are found within the several cavities formed by the struc- tures. In order to perform these functions, the skele- ton must be composed of a hard and unyielding ma- terial which retains its shape, but it must have at the same time a certain degree of elasticity. For these I 2 GOOD HEALTH reasons the skeleton is constructed of bone, and it will be of interest to learn something of the composition and peculiarities of this substance. Bone consists of animal and earthy matter. The former is chiefly a substance which is converted by boiling into gelatin. It also contains fat and blood- vessels. The animal tissue in bone makes it tough and elastic, while the earthy matter, known as *'bone earth," consisting principally of phosphate of lime, furnishes the required hardness. In very early life the animal matter forms about one-third and the earthy matter two- thirds of bone; later in life, the proportion of lime is somewhat in- creased in amount, and the bone becomes denser. This explains why the bones of children are more elastic than those of adults. When considerable force is used a child's bone is apt to bend like a green stick, rather than break through, as in the case of adult bone. Rickets is a disease of childhood, and is due chiefly to an insufficient amount of earthy matter. In this condition the bones, for want of hardness, become bent and distorted, the deformity being particularly marked in the bones of the lower extremity which, for the time being at least, are unable to support the weight of the body properly. Bone is composed of compact and cancellated tis- sue. The former consists largely of earthy matter and is exceedingly dense and hard like ivory. The latter is a network of thin plates or columns and is sponge-like in appearance. The compact tissue forms THE STRUCTURE OF THE BODY 3. the outer portions of bone and is increased in amount where great strength is required, as in the shaft of the femur or thigh bone. The cancellated tissue is par- ticularly abundant where bones become enlarged in order to form joints, as in the ends of the long bones. Although cancellated tissue is very light, it is also very strong ; a portion corresponding in size and shape to a piece of loaf or lump sugar will support a weight of three or four hundred pounds. A piece of com- pact tissue an inch square and half an inch in thick- ness will support a weight of five thousand pounds.. In formation of the skull, where great strength is- necessary to protect the brain, the bone is composed of two layers of compact tissue with a small amount of cancellated tissue between. The long bones are hollow for the same reason that tubular columns are used in constructing a building — to secure strength with the minimum weight. The hollow part or canal in the shaft of long bones, as well as cancellated tissue, contains a substance called marrow or oil of bone. In the canals this substance is known as yellow marrozv, and is composed almost entirely of fat. That found in the cancellated or spongy tissue of bone and known as red marrow is three-fourths composed of water and contains but a small amount of fat. In very early life all the mar- row of bone is of the red kind. It is now known that all of the red corpuscles and some of the white cor- puscles, or leukocytes, of the blood, which will be referred to again later, are formed in the red marrow of bone. In addition, the yellow marrow has some- 4 GOOD HEALTH thing to do with the nourishment of the tissues, par- ticularly in emergencies. The canals in the bones of birds communicate with the lungs, and contain air instead of marrow, thus rendering them very light and properly adapted to flight. Bone is supplied with nutrition from two sources : the periosteum and the nutrient arteries. The periosteum is a firm and resisting fibrous mem- brane, pinkish in color and closely adherent to the bone. It covers it at all points except at the ends where joints are formed and where cartilage exists. In the substance of periosteum are found blood-ves- sels which divide and subdivide and pass into minute openings in the compact tissue of bone to supply its outer surface with nutrition. When the periosteum is detached from a bone, either by accident or other- wise, the compact tissue is deprived of its principal means of nutrition, and death or '"necrosis" — corre- sponding to ''gangrene" in the soft tissues — follows. The nutrient arteries supply the interior of the bone with nourishment. Bones are also supplied with nerves and absorbents or lymphatics. The power of absorption possessed by the latter is so great that ivory pegs employed to hold in place the broken ends of bone unable to unite by natural processes, have been absorbed. The shape of a bone depends largely upon its use. The long bones, of which the femur or thigh bone is a type, are not only used for support, but act as levers to lift or move the various parts of the body THE STRUCTURE OF THE BODY 5 through muscular attachment. They are composed of a shaft and two extremities. The short bones are found where a number of joints are required for Hm- ited motion combined with strength — for instance, the carpus or wrist. Flat bones aid in the construction of cavities, help to protect their contents, and provide for muscular attachment, as the bones of the skull and shoulder blades. Examples of irregular bones are the superior and inferior maxillary bones, or the upper and lower jaw, and the vertebrae or bones forming the spine. The skeleton, which is composed of two hundred bones, not including some small ones in the ear, is the framework of the body; it supports the soft tis- sues, protects the internal organs, and serves for the attachment of muscles. It consists of a central col- umn or spine, four extremities — two upper and two lower — and three bony cavities, namely, the cranium or skull, containing the brain, the thorax or chest, enclosing the heart and lungs, and the pelvis or basin, holding the pelvic and some of the abdominal or- gans. The arrangement of the bones is as follows : Spine 26 Skull 22 Hyoid bone I Sternum i Ribs 24 Upper extremities 64 Lower extremities 62 200 6 GOOD HEALTH The spine or backbone, which is about one-third the length of the body, is an articulated column com- posed of a number of bones (vertebrae) joined to- gether and forming three slight curves which aid in the formation of cavities for the protection of in- ternal organs. These curves also add strength to the column and go far to diminish shocks to the spinal cord and brain which might occur if the column were straight. The spine supports the skull and its contents and protects the spinal cord, which is contained in a canal formed by the union of the vertebrae. The spinal column rests upon the posterior and upper portions of the pelvis. The freest movement of the spine is found in the neck or cervical region, and the least in the back be- tween the shoulders where the ribs are connected with the spine. The weakest part of the spine is at its lowest part where the column is very movable. The skull is for the lodgment and protection of the brain and its membranes, blood-vessels and nerves. In A'ery early life bone is not hard but is somewhat simi- lar in consistence to cartilage. The fontanelles, or ''soft spots," on an infant's head represent bones which have not become hardened or ossified, or brought closely and firmly together by this process. This condition usually disappears after the child is a year or so old. At birth and for some time after- wards even the long bones are not sufficiently hard or dense to be capable of supporting the body; and for this reason infants should not be placed on their feet too early. Fig. I. — The skeleton. . 7 8 GOOD HEALTH A large opening exists at the base of the skull called the foramen magnum, through which the spinal cord passes from the brain to the canal in the vertebral column. Other and smaller openings are found in the skull for the passage of blood-vessels and nerves. The hyoid hone is a small and somewhat horse- shoe shaped bone found above the *'Adam's apple." It helps to support the tongue and also furnishes at- tachment for muscles. The sternum or breast hone is flat and narrow, about seven inches long, and may be easily felt under the skin in the front and upper part of the chest. It supports the clavicles, or collar bones, and the front end of the ribs with the exception of the last two. There are twenty- four rihs, twelve on each side, being numbered from above downwards. All of them articulate or join in the back with the vertebrae or spinal column, and in the front the upper ten con- nect through the medium of cartilage with the ster- num. The two lower ribs, the eleventh and the twelfth, are connected only with the spinal column behind, and are known as ^'floating ribs." These are rarely broken, for when struck or rested upon, they sink inwards because they have but one attachment, and usually escape injury. The peculiar arrangement of the ribs renders them very important agents of respiration, for when they are elevated by muscular action during inspiration, the chest becomes enlarged and the air passes readily into the lungs. In expiration the ribs are depressed, the chest cavity is diminished in size, and the air in the THE STRUCTURE OF THE BODY 9 lungs is expelled. The diaphragm, which will be re- ferred to again later on, plays an even more important part than the ribs in connection with respiration. Each upper extremity is composed of thirty-two bones, named as follows : scapula or shoulder blade ; clavicle or collar bone; humerus or arm bone; ulna and radius, the bones of the forearm; eight carpal bones, composing the wrist; five metacarpal bones, forming the framework of the palm and back of the hand, and fourteen phalanges or bones composing the fingers and thumbs. The scapula is a thin, flat, triangular bone, situated at the upper part of the back. It joins the clavicle and humerus at its outer end or border. It helps to pro- tect the contents of the chest and forms a broad sur- face for the attachment of muscles. The clavicle is shaped somewhat like the italic letter s, and may be easily felt as the upper and most super- ficial bone at the base of the neck in front. It extends from the sternum to a process on the outer portion of the shoulder blade; it holds the latter upward, back- ward and outward. , The humerus is the longest and strongest bone of the upper extremity. It has a shaft and two extremi- ties, the upper one being received in a cup-like depres- sion in the outer part of the shoulder blade. The humerus has a greater range of motion than any other bone in the body, and is most often removed from i4;s position and dislocated. The ulna and radius compose the forearm ; the ulna with the humerus forms the elbow- joint. The upper 10 GOOD HEALTH end of the radius does not take part in this joint or articulation. It is attached by ligaments to the outer side of the ulna, over which it freely ghdes or rotates, allowing the hand to move inwards and outwards. Its lower end, which is comparatively broad, takes part in the formation of the wrist-joint. The ulna takes no part in this articulation. The carpus or wrist is composed of eight small irregular bones arranged in two rows. This arrange- ment insures strength, motion and elasticity. The metacarpus consists of five long bones con- necting the wrist with the bones of the fingers and thumb, and forms the framework of the palm and back of the hand, where they may be easily identified. The phalanges, which are miniature long bones, are fourteen in number : three for each finger and two for the thumb. ' Their position may be easily demon- strated by bending or flexing the fingers. This ar- rangement is such that when the hand is opened, the fingers do not correspond in length ; but when closed, as in grasping an object, there is no apparent differ- ence. This is necessary, for if the fingers when closed were uneven, the grasping power of the hand would be diminished. Each lower extremity consists of thirty-one bones, one less than in the upper extremities. They are as follows : the haunch or pelvic bone ; the femur or thigh bone ; the tibia, leg or shin bone ; and the Hhula or splint bone; the tarsal bones (seven) or instep; the metatarsal bones (five) or ankle; the phalanges or toes, and the patella or knee cap. THE STRUCTURE OF THE BODY ii The pelvis is composed of the haunch bones and two smaller ones which join them behind, the sacrum and coccyx, constituting the lower portions of the ver- tebral column. The pelvis supports the trunk of the body and protects the pelvic and some of the abdom- inal organs. The femur is the strongest and longest bone in the body. Its length is characteristic of the human skele- ton. In the erect position of man, the tips of the fingers reach to about the middle of the thigh, while in the orang-outang, the fingers reach to the ankle. This difference is also due to the comparative short- ness of the arms in the human skeleton. The upper end of the femur is composed of a spherical head which connects obliquely with the shaft of the bone by a long neck. The function of the latter is to keep the thigh bone a proper distance from the pelvis and to prevent interference with locomotion. This round head rests in a depression or socket in the pelvis. The lower end of the femur i^ very large and broad, and articulates with the upper extremity of the tibia and, with the patella, or knee cap, forms the joint. The tibia or shin bone and fibula or splint bone form the leg. The tibia, which is very superficial, having only the skin as a cover, is the larger of these two bones, and is constructed mainly for strength and support, although some muscles are attached to it. The fibula, companion bone of the tibia, is external to it and very slim. It aids in supporting the tibia, takes part in the formation of the ankle-joint, and furnishes attachment for a number of muscles. 12 GOOD HEALTH The tarsus, or instep, corresponds to the carpus, or wrist, in the upper extremities ; it consists of seven bones, while eight bones form the wrist. The tarsal bones, which form the arch of the foot, possess great strength; this is necessary to support the weight of the body. If the ligaments and other tissues which hold the bones of the tarsus together, particularly underneath, become relaxed, torn, or otherwise dis- abled, the instep sinks, the arch of the foot is more or less destroyed, and what is known as ''flat foot" or ''broken arch" occurs. This not infrequently follows certain diseases of the bone. Some people are natu- rally flat-footed. The metatarsal bones of the foot correspond to the metacarpal bones of the hand and are the same in number. They form the framework of the foot. The phalanges are fourteen in number and corre- spond to the phalanges of the hand. The patella, or knee cap, is situated in front of the knee-joint. It lies in the tendon of a large muscle, and assists in the formation and protection of this joint. When the leg is extended and the muscle re- laxed, the patella will be found to be freely movable. Sometimes the little closed sack over the patella, the interior of which is moistened with a fluid to prevent friction, becomes injured and inflamed and very much increased in size, due to the presence of the fluid. This is known as "house-maid's knee," for it is some- times produced by resting on the knees, as in the act of scrubbing. There are, however, other and probably more frequent causes for this affection. THE STRUCTURE OF THE BODY 13 ARTICULATION— JOINTS Bones are connected at different points in the skele- ton ; such a connection is called an articulation or joint. Some are immovable — those in the skull, for instance; others slightly movable, as the joints of the spine ; while the greater number are freely movable, as the knee and shoulder joints and joints of the fingers and toes. Some joints have a gliding movement, as the wrist and instep. A ball and socket joint, where a globular head is received in a cup-like cavity, permits move- ment in several directions, as in the shoulder and hip. In a hinge joint the motion is limited to a forward and backward movement, as at the elbow and knee. The structures entering into the formation of joints are as follows : bone, cartilage, ligaments, tendons, synovial memhranes, blood-vessels, and nerves. Bone has already been described. Cartilage, or ''gristle,"' covers the ends of bones which form joints. It acts as a buffer, protecting the adjacent bony surfaces from friction and prevent- ing shock which would occur if these surfaces were directly applied to each other. This is particularly noticeable in the vertebrae of the spinal column. The continual pressure brought to bear on cartilage would cause pain, inflammation and disease if it were supplied with blood-vessels and nerves ; consequently it is destitute of these structures, and is known as non-vascular tissue. It absorbs its nourishment from the surrounding parts by the process known as 14 GOOD HEALTH imbibition. Cartilage is also- found lining tubes, such as the air passages, ears and nose, where it is necessary that channels be kept permanently open. Continued pressure on cartilage diminishes its thick- ness, and during the day we may lose half an inch or so in height. However, rest and the recumbent posi- tion at night restore the cartilage to its proper thick- ness. Leaning too much on one side may cause a per- manent change in the cartilage, and consequent de- formity. Ligaments are composed of two kinds of tissue : white Hhrous and yellow elastic. The former are more common and connect the extremities of bones forming the joints. White fibrous tissue is very strong and flexible but it does not stretch; and while it permits the necessary movements of the joints, it does not al- low the articular ends of the bone forming the joint to become displaced. When a bone is dislocated, the ligaments, as a rule, are either ruptured or torn from their attachment. The ligaments composed of yellow elastic tissue are very elastic, and are found in parts where con- siderable range of motion is required, as in the cervi- cal region of the spinal column. This elasticity aids in returning the parts to their proper place after movement. Synovial membranes are delicate structures con- nected with the movable joints lining the inner side of ligaments; but they do not extend between the articular surfaces of the bone. They secrete a thick, glairy fluid, resembling the white of egg, and known THE STRUCTURE OF THE BODY 15 as synovia or "joint oil/' the function of which is to lubricate the surfaces of the joint, and thus prevent friction. These membranes often become inflamed; this condition is called ''synovitis." MUSCLES Muscles are bundles of reddish-brown fibers, having the power of contraction. There are two kinds : vol- untary or striped muscles, and involuntary or un- striped muscles. The terms "striped" and "unstriped" refer to the microscopical appearance of the individual fibers composing the muscles. The voluntary muscles are under the control of the will, and comprise the bulk of the muscular system. They are attached to the different parts of the skele- ton and act on the bones as levers ; they are agents of locomotion. They also protect the various struc- tures beneath them, and give grace and symmetry to the form. When the muscles are poorly developed or become diminished in size, a person becomes angular and bony. The lean meat of animals used for food is voluntary or striped muscular tissue. The voluntary muscles differ in length and shape, and are designated as long, short, broad, etc. They are arranged in pairs, for as a rule there are corre- sponding muscles on each side of the body. There are over four hundred muscles attached to the human frame. At many points their outlines are apparent to the eye, and are used by physicians as guides to the location of important vessels and nerves. Muscles are surrounded by thin web-like tissue i6 GOOD HEALTH known as fascia, which serves as a support and les- sens friction while the muscles are in action. Fig. 2. — Biceps at rest. Voluntary muscles are composed of a belly and two extremities. The more fixed extremity is called the Fig. 3. — Biceps contracted. origin, and the movable one the insertion, though in some muscles the origin and insertion are equally mov- THE STRUCTURE OF THE BODY 17 able. During contraction the origin and insertion draw closer together, the muscle in action thereby becoming shorter and thicker. This can be easily dem- onstrated by raising a heavy weight with the hand, when the ''biceps," the large muscle on the front of the upper arm, will be seen to thicken and bulge forward. Muscles gradually diminish in size towards their extremities. The fibers at this point are replaced by a firm and resisting substance composed of white fibrous tissue known as "tendon." This is directly and intimately connected with the periosteum, and sometimes directly with the bone. Tendons differ in appearance from the muscular tissue in being white and glistening. An "aponeurosis" is simply an ex- panded tendon and is found where the muscle has a broad attachment. Muscles are abundantly provided with blood-vessels, nerves and lymphatics in order that there may be a constant supply of nourishment, that there may be a prompt response to stimulus from the nerve cen- ters, and also that waste matter may be absorbed. Tendons have but few blood-vessels, and only those of larger size have nerves. In the disease known as tetanus or "lock jaw," the nerve stimulus is so strong and the contraction of the muscles so powerful that fibers are sometimes rup- tured. The stiffness of the body which ensues after death, known as "rigor mortis," is due to the solidifi- cation of some of the fluid portions of the muscles; this again is followed within a few hours by the re- i8 ^ GOOD HEALTH laxation of the body. It is believed that this rigidity is not so apt to occur in persons killed by light- ning. If muscles are not sufficiently used they become diminished in size and atrophy takes place. From continued non-use they may undergo degeneration, from which there is no recovery, for nature is not favorable to tissue which is of no use. Thus the value of exercise is apparent. Hypertrophy repre- sents the opposite condition to atrophy, and the mus- cles become increased in size. This is due to unusual and continued exercise and activity. The heart muscle becomes hypertrophied when it is necessary that this organ make up for the partial loss of function due to diseased valves. The involuntary or unstriped muscles, which are not under the control of the will, are not connected with bones, but form the muscular covering of some of the internal organs, as the stomach and intestines, and also the muscular coat of the blood-vessels. The contraction of this form of muscular fiber is not abrupt and rapid as in voluntary muscles, but slow, worm-like and unequal, and does not affect all portions of the muscles at the same time. The value of this during digestion will be referred to later. The invol- untary muscles have no tendons, the muscular fibers simply interlacing with each other. Although the heart is an involuntary muscle and not under the con- trol of the will, the fibers are striped in a manner somewhat similar to voluntary muscular fibers. This is the only instance of the kind. THE STRUCTURE OF THE BODY 19 BLOOD Blocxi is the great nutritive fluid of the body; it distributes to the different tissues oxygen and nourish-^ ment necessary for their existence. If the system is not constantly supplied with oxygen, death quickly^ Fig. 4. — Human red blood corpuscles and two white corpuscles. follows, as in drowning. The blood has also the Yery important function of removing from the body through certain organs, principally the kidneys, lungs and skin,, worn out and waste matter which, if retained, may either seriously affect the health or prove fatal. Blood is composed of liquid and solid matter. The former is known as plasma and constitutes about two-thirds of the blood; it is almost colorless whea separated from the soHd matter, or corpuscles. The 20 GOOD HEALTH plasma contains the principal elements of nutrition which it distributes to the various tissues through the body, receiving in return waste matter to be discharged through the different excretory organs. The corpuscles or solid portion of the blood in the plasma are divided into red and white corpuscles, the latter being known as *ieukocytes." The red corpuscles are far more numerous and con- spicuous than the leukocytes or white corpuscles, and resemble in appearance a coin thinned in the center on both sides, or bi-concave. These little bodies are ex- ceedingly small, thirty-five hundred of them laid side by side on their flat surface being required to cover the space of an inch, and they of course are not visible to the naked eye. Physiologists have calculated that there are over fifty billion red corpuscles in the human body. When examined individually under the micro- scope they appear straw-colored, but when vast num- bers are crowded together, they present the charac- teristic red color. They are oxygen carriers. They re- ceive this gas from the air in the lungs and distribute it to the tissues throughout the system. The white corpuscles are much larger than the red ones, and are more globular in form. Until recent years the function of the white corpuscles was in doubt; now it is known that besides other uses they are extremely important agents in the destruction of bacteria or germs which find their way into the sys- tem. The leukocytes are most lusty fighters, and with the aid of the microscope may be seen actually to draw the infectious germs within themselves for the THE STRUCTURE OF THE BODY 21 purpose of destruction. This exceedingly important and interesting function will be referred to again in a subsequent chapter. The amount of blood in the human body represents about one-twelfth of its weight. It is an alkaline fluid and heavier than water, having a specific gravity of 1055. Arterial blood, or that which has been purified in the lungs, is bright red owing to the presence of oxygen; while the venous blood, which is largely de- prived of oxygen and contains poisonous gas and waste matter, is of a bluish or purplish color. Some tissues, such as hair, cartilage and nai!s, are not supplied with blood, but receive their nutriment by their absorption or imbibition in a manner similar to cartilage. Coagulation, which occurs when a blood-vessel is opened, is nature's means of arresting hemorrhage. Coagulation sometimes takes place within vessels them- selves under certain abnormal conditions of the blood or vessels. In connection with the various subjects contained in this book reference will frequently be made to Organs, glands, secretions, excretions, and mucous and serous membranes. For the sake of convenience, these terms will be explained together. An organ is a part of the animal system having a definite function to perform; for instance, the heart. A gland is also an organ, but in addition it either takes from the blood certain waste or poisonous mat- ter which it discharges from the body unchanged, Z2 GOOD HEALTH known as an excretion — as the urine — or it manu- factures from material removed from the blood a product which is found nowhere else and is employed in the body for a special purpose ; this is a secretion and the gastric juice is an example. Mucous and serous membranes are found in the interior of cavities, sacs and tubes. Mucous mem- branes line structures which open externally, such as the respiratory and alimentary tracts, while serous membranes cover the inner surface of cavities and tubes which are closed and have no communication with the outer world, such as the pleural and peri- cardial cavities. CHAPTER II THE VITAL processes: CIRCULATION, RESPIRATION^ DIGESTION, NERVOUS SYSTEM AND LYMPHATIC SYSTEM. CIRCULATION Blood-Vessels In order that our bodies may be kept alive, there must be some form of transmission or circulation by which the various tissues are supplied uninterruptedly with nourishment. The need of that is not confined to human beings and animals, but applies to the lower forms of life as well as to plants and trees. The tree obtains its nourishment from the ground and trans- mits to its branches material to maintain their exist- ence and growth. A beautiful illustration of this may be found in the leaf in which the stem divides into many little ramifications for the distribution of nour- ishment. In the higher order of animal life nourish- ment is transmitted through the medium of blood, which is carried tO' every part of the system by tubes or blood-vessels. These are divided into arteries,, capillaries and veins. Arteries are vessels which carry blood away fran the heart. The aorta, which is the largest artery in the body and the beginning of the arterial system, is 2% 24 GOOD HEALTH connected with the left ventricle of the heart, and through it the blood passes to the various parts of the body. The walls of the arteries are composed of three coats or layers, namely, the external, middle and in- ternal coat. The external coat consists of white fibrous tissue which is very strong and tough and whose func- tion is protective. The strength and resistance of this coat are well exhibited when ligating or tying an artery, as surgeons are often obliged to do. The liga- ture is passed around the vessel and the ends drawn tightly together and tied for the purpose of closing the artery. This constriction usually severs the middle and internal coats, but leaves the external coat practi- cally intact or without serious injury. The middle coat of the arteries is composed of mus- cular and yellow elastic tissue which exerts a pressure upon the contents of the vessel and helps to regulate and force along the blood supply. The large amount of yellow elastic tissue in the arteries explains why the coats of these vessels are much thicker than those of the veins. It also accounts for the elasticity which is characteristic of arteries, and for the fact that arteries remain open when empty. The latter condi- tion gave rise in very early times to the belief that these vessels contained only air, and for this reason were named arteries or *'air carriers." Arteries pulsate, and when severed the blood es- capes in spurts and jets. This is due principally to the action of the heart and partly to the contraction of the arteries thems'elves. THE VITAL PROCESSES 25 An artery in its normal condition may be likened to a rubber tube. If water is forced into a rubber tube it stretches a little to receive the fluid, and immediately contracts to its original caliber, thus aiding in forc- ing along its contents; this is elasticity. Time and exposure will render the rubber tube stiff, brittle and weakened. Under these conditions it is not elastic, and when force is applied within it may, under suffi- cient pressure, crack or break open with an escape of its contents. This is practically what occurs in so-called "hard- ened" arteries which frequently develop late in life. The middle coat containing the elastic and muscular tissue undergoes degeneration and becomes weak and brittle, and its elasticity largely disappears. When this occurs the smaller arteries particularly are often unable to resist the pressure of blood. The rupture of one of these little vessels in the brain giving rise to hemorrhage and pressure upon this organ causes pa- ralysis in some part of the body, known as apoplexy. A hemorrhage on one side of the brain causes paraly- sis on the opposite side of the body. The reason for this will be explained in the section relating to the nervous system. As arteries go farther into the tissue, they become exceedingly small and lose their external and middle layer, and have but one coat. They are then known as capillaries and become so minute that the red cor- puscles in order to pass through are sometimes obliged to "double up" and pass one by one. The thinness of the capillary walls and the slow and uniform current 26 GOOD HEALTH of blood in these vessels enable them, as already stated, to supply the tissues with oxygen and nourishment urgently needed, and to receive in exchange waste matter which is thrown out of the body by the excre- tory organs. The capillaries, after having supplied nourishment to the tissues and received waste matter in return, take on a second coat, and later still another one. These vessels, now having three coats, are known as veins. The middle coat contains but little of yellow elastic tissue, which accounts not only for the rela- tive thinness of the walls of these vessels com- pared with arteries, but also for the fact that they collapse when empty. Veins do not pulsate as arteries do, for they are further removed from the action of the heart; therefore, hemorrhage from a vein is a continuous flow rather than the spurt which occurs when an artery is severed. With the exception of those in the cranial, thoracic and abdominal cavities, veins are supplied with valves formed by a duplication or folding over of the in- ternal coat of these vessels ; this allows the blood to flow in one direction only, towards the heart. These valves are very necessary, as the current of blood in the veins is mainly upward and against the force of gravity; moreover, the pressure of the blood in the veins is about only one-fourth of that in the arteries. Sometimes the valves become useless, and distention and distortion of the vessels occur. This is noticeable in the condition known as "varicose veins," which often occurs in the legs. THE VITAL PROCESSES 27 The circulation of the blood throughout the body- takes place in the following manner: The venous blood, containing worn out and waste matter and prac- tically deprived of oxygen, is collected throughout the body by two large veins which discharge their contents into the right auricle of the heart. The right auricle contracts and forces its contents into the right ven- tricle. The contraction of the ventricle follows. The valve guarding the opening between these two cavities closes, and the blood, unable to return to the auricle, is driven into a large blood-vessel which divides and carries the blood into the lungs. Upon reaching the lungs the veins grow smaller and exceedingly numer- ous, and at last become capillaries and surround the minute vesicles or pockets composing the lungs. Here a most important change takes place ; for it is at this point that the blood frees itself of carbonic acid gas and other waste and poisonous products collected throughout the system and receives in return oxygen from the air contained in the vesicles. The blood, now purified and enriched and in a condition to nour- ish the tissues of the body, is forced by the continuous action of the right side of the heart from the lungs into the left auricle. The latter then contracts and the blood passes into the left ventricle. The valve between these two cavities closes as it does on the right side, and the blood is driven into the aorta, the largest artery in the body. Thence it proceeds into the smaller arteries, and ultimately the capillaries where the in- terchange of nourishment and waste matter takes place. After performing this function, the capillaries 28 GOOD HEALTH become continuous with the veins and the circulation is completed. Heart The heart is a pear-shaped muscular organ or pump, about the size of a closed fist of a man. The average adult heart is about five inches long, three inches through, and weighs from eight to twelve ounces. It occupies a position in the chest just behind the sternum, or breast-bone, and lies between the lungs mainly on the left side. The large end, or base, of the heart is above and points towards the right side, while the smaller end, or apex, is downward and to the left. A line drawn across the sternum or breast bone, at the upper border of the cartilage of the third rib in front, would indicate the base of the heart. The apex, or smaller end, of the heart is found between the fifth and sixth rib's and three and a half inches to the left of the middle line of the chest ; at this point, the pulsa- tion of the heart can be distinctly felt. The heart is composed of four cavities or chambers : two auricles and two ventricles. The auricles are above and the ventricles below. Again, the heart may be divided into a right and left side, each having an auricle and ventricle. The ventricles do not connect with each other nor do the auricles, but an auricle connects with a ventricle of the corresponding side. The opening between the auricle and ventricle is guarded by a valve which is so arranged that the blood may pass from the auricle to the ventricle, but in nor- mal condition it cannot return. If this were not so THE VITAL PROCESSES 29 the circulation of the blood would be constantly inter- fered with. The ventricles are larger than the auricles and their muscular walls are much stronger, particu- FiG. 5. — The heart and large blood-vessels. A, right ventricle; B, left ventricle; C, right auricle; D, left auricle; E, aorta; F, pulmonary artery. larly those of the left ventricle, which must drive the blood received from the lungs throughout the entire system. The auricles contract together, as do the ven- tricles. Between the complete contraction of the ventricles 30 GOOD HEALTH and the beginning of the contraction of the auricles there is a pause which, although imperceptible, pro- vides a measure of rest for the heart — a very import- ant consideration. Otherwise the heart would be un- able to perform its function, for nature requires that all organs and tissues shall have a period of repose. Fig. 6. — Diagram showing course of the blood through the heart. This double action — the contraction of the auricles and ventricles — represents one pulsation of the heart. There are from sixty to eighty pulsations a minute. The heart is endowed with enormous power ; it is esti- mated that the energy exerted by this organ in twenty-four hours would raise a ton weight one hun- dred and twenty-five feet from the ground. THE VITAL PROCESSES 31 The cavities of the heart are lined with a very deli- cate and smooth membrane known as the endocardium. The endocardium is continuous throughout the whole system of blood-vessels, forming the internal coat or lining of the arteries and veins, and the only coat of the capillaries. The function of this lining membrane is largely to prevent friction. It is also necessary to protect the outside of the heart from contact. For this reason it is surrounded by a closed sac lined with a serous membrane called the pericardium. One side of this sac is attached to the walls of the heart; the other to the surrounding tissue. Below, considerable space is provided in which the lower portions, or apex, of the heart may move about. The interior of this sac is exceedingly smooth and contains a small amount of fluid; this is very necessary as the constant action of the heart would otherwise excite friction. RESPIRATION Respiration is the act or process of breathing, and IS the means by which oxygen contained in the air and necessary to our existence reaches the blood for dis- tribution throughout the body, and is also the means by which poisonous gases and waste matter are thrown off from the blood. Respiration is divided into inspiration and expira- tion. The structures involved in this function are ^s follows : Mouth, nose, larynx, trachea, bronchial tubes and the air vesicles or cells, of which the lungs are 32 GOOD HEALTH chiefly composed. These different structures consti- tute the respiratory tract. A close examination of the throat will show two openings. The back, or posterior, one is the upper part of the esophagus or ''gullet." In front of this and just behind and below the base of the tongue, is the upper part of the larynx or ''wind-pipe." This consists of a cartilaginous box containing fibrous bands which stretch from the front backward, two on each side, one above the other. These are called vocal cords. The upper, or superior, pair have no special function known at present; the lower, inferior or true, vocal cords are extremely important, for it is their vibration during expiration, or when the air is expelled from the lungs, that produces the voice. The larynx may be easily located externally. The prominence known as "Adam's apple" in the neck forms its upper portion, the lower border being about one and a half inches below. The opening into the larynx is covered with a little leaf-shaped piece of cartilage known as the epiglottis, which aids in pre- venting food and other foreign substances from en- tering the wind-pipe. The tongue also aids in this protection, for in the act of swallowing, the base of the tongue is carried backward and partly covers the open- ing of the larynx. The trachea, or wind-pipe, is a continuation of the larnyx in the form of a tube about four or five inches long, and three-quarters of an inch to an inch in diameter. It is composed of rings of cartilage, fibrous membrane and a small amount of muscular tissue. THE VITAL PROCESSES 33, These rings have the same function as the cartilage which forms the larnyx, i. e., to keep the walls sepa- rated or the tube open at all times. The trachea di- vides into two branches known as the right and left bronchi. Fig. 7. — Showing the relative position of heart and lungs in the cavity of the chest. Upon entering the lungs, the bronchi further divide and subdivide until the parts become exceedingly small and end in little pouches known as vesicles, or ''air cells." It is interesting to note that in the division of the trachea into two branches, the one on the right is somewhat larger than the one on the left and appears. 34 GOOD HEALTH to be the continuation of the trachea. It is for this reason that small articles accidentally sucked into the air passages are more often found in the right bronchus. The respiratory tract is lined throughout with mu- cous membrane which is kept moist and prevents fric- tion during the passage of air through the tube. The construction of this membrane in the upper portion is very peculiar and extremely interesting, for upon its surface are found little hair-like processes which are constantly waving towards the outer world. This is of valuable aid in preventing the entrance into the lungs of dust and other irritating particles. The lungs are two pyramidal-, cone- or triangular- shaped organs situated in the chest with the base be- low and longer behind than in front. Each lung weighs about twenty ounces, the right being a little heavier than the left. They are divided by deep fis- sures into lobes or sections, the right lung having three lobes and the left two. The small, or upper, portion or apex extends to, or just above, the clavicle or collar bone; the larger, or lower, portion or base descends in front to the sixth rib ; the side to the eighth, and the back to the tenth. The lungs are surrounded by a closed sac lined with a serous membrane called the pleura, similar to the pericardium covering the. heart and possessing the same functions, i. e., fur- nishing protection and preventing friction. This sac or membrane frequently becomes inflamed by dis- ease or accident: the condition is known as pleu- risy. THE VITAL PROCESSES 35 The lungs are composed of millions of minute pouches or air cells about one-two hundredths of an inch in diameter. They have already been referred to as the termination of the bronchial tubes. The enor- mous surface represented by these little pockets, which receive the air taken in with respiration, would, if spread out, cover an area of about six hundred square feet. The walls of the air cells and the capillaries surrounding them are so exceedingly thin that the interchange of gases and other products between the blood and the inspired air readily takes place. Under ordinary conditions we breathe from sixteen to twenty times each minute. During inspiration the air is carried into the lungs by the descent of the diaphragm, which exerts a suction force as it is carried downward, and also by the elevation of the ribs which increases the size of the chest. Expiration, or the expulsion of air from the lungs, is effected by the elevation of the diaphragm' and the descent of the ribs and a partial collapse of the lung. Although these are the principal agents of expiration, there are other elements, notably the ac- tion of certain muscles which, although of lesser im- portance, render valuable aid when there is great diffi- culty in breathing, as in certain affections of the lungs. Then the action of muscles about the neck and shoul- ders becomes very apparent. The diaphragm is a muscular partition which sep- arates the contents of the chest from the abdominal organs. Above the diaphragm are found the heart and lungs, and below, the stomach, liver, intestines and 26 GOOD HEALTH other abdominal contents. Its function is very im- portant both in connection with respiration and di- gestion. The lungs during life are never completely collapsed. Complete collapse is prevented by about one hundred cubic inches of air, which cannot be expelled, called ''residual" air. Another hundred cubic inches known as ''reserve" air usually remain in the lungs after ex- piration, and are used during increased physical exer- tion as in running, rowing, etc. The "tidal" air repre- sents the amount taken into the lungs at each ordinary inspiration, and consists of about thirty cubic inches. During violent exercise, however, an additional hun- dred cubic inches may be taken into the lungs at each inspiration. This is known as "complemental" air. The extreme capacity of the lungs would therefore be the sum of the residual, reserve, tidal and comple- mental air, amounting to three hundred and thirty cubic inches. The vital, or respiratory, capacity, how- ever, is the amount which can be breathed out after the deepest possible expiration, and would therefore not include the residual air. DIGESTION The alimentary tract, or canal, comprises the several structures or organs through which food and drink enter the body to be digested and absorbed. The alimentary tract is nearly thirty feet long. It b)egins at the mouth and continues through the pharynx, or throat; the esophagus, or gullet; the stomach, and the small and large intestines, the latter terminating THE VITAL PROCESSES 37 at the external opening, or anus. These structures will be spoken of in their order from above down- wards. Mastication is the first step in digestion. This takes place in the mouth, the most important agents involved Fig. 8. — The jaws and the teeth, i, 2, incisors; 3, canines; 4, 5, bicuspids; 6, 7, 8, molars; a, vein; b, artery; c, nerve; d, vein, artery, and nerve. being the teeth. In man these are so fashioned and arranged that food may be cut, torn and ground, the teeth for each process being respectively incisors^ canines and molars, or grinders. Their formation 38 GOOD HEALTH shows that man is adapted to all sorts of food. Among the animals, the cow, for instance, which obtains its food principally by grazing, has well developed molars or grinders ; while dogs, or animals that depend prin- cipally upon meat for sustenance, have sharp or tusk- FiG. 9. — Salivary glands. like teeth called ''canines," which enable them to tear meat from the bone. The teeth are inserted along the edges of the alveolar processes of the superior and inferior maxillary bones, or upper and lower jaw bones. There are thirty-two teeth in all, sixteen in each jaw, arranged as shown in the diagram (Fig. 8). The portion of a tooth pro- jecting beyond the gum is called the crown ; the rest is imbedded in the bone. The crown is covered with THE VITAL PROCESSES 39 enamel, the hardest structure of the body, which pro* tects the teeth against various destructive agents and prevents too rapid wear as the result of friction dur~ ing mastication. The teeth cut and grind the food so that all parts of it can be exposed to the digestive fluid. When food is introduced into the mouth, it is made soft and wet by an alkaline secretion known as saliva or ''spittle" which is secreted by three glands, the parotid, the submaxillary and the sublingual, which discharge their contents into the mouth through small ducts or tubes. The flow of saliva may be stimulated by the anticipa- tion of palatable food, i. e., through a mental influence. The parotid, the largest of the three glands, is situated behind the angle of the jaw. The characteristic de- formity or swelling below and in front of the ears in the disease known as ''mumps," is due to the enlarge- ment of these glands. The secretion of the parotid accomplishes mainly the moistening of the food; the submaxillary and sublingual secretion is more viscid or "slippery" and greatly facilitates the passage of the food downwards. In reptiles where there is no mas- tication, it is this slimy secretion that enables them to swallow substances of a very large bulk; by this means a comparatively small snake is able to swallow a good- sized rat. Saliva also renders important aid in diges- tion by changing starch into sugar, the form in which it is taken into the system. If food is not properly masticated the digestive ap- paratus sooner or later is sure to suffer, and indirectly, serious results may follow. Therefore, the importance 40 GOOD HEALTH of giving proper and early care to the teeth cannot be overestimated. The pharynx, or throat, is a continuation of the mouth and has no special digestive action. The esophagus, or gullet, is a muscular tube about eight or nine inches long which is collapsed when not functioning. It begins at the lower border of the phar- ynx and passes downward through an opening in the diaphragm and becomes continuous with the upper, or cardiac, end of the stomach. This tube accelerates by its muscular action the passage of food downward to the stomach. Were it not for its muscular coat, swal- lowing, or deglutition, would be practically impossible. Difficulty in this direction sometimes occurs when the nerve supply in this tissue is interfered with. When one eats too rapidly, particularly of food which is dry and has not been properly masticated, it is difficult for the esophagus for the moment to force the food down- ward. The common phrase, "stuck in the throat," in- dicates the discomfort which occurs in this condition. For many reasons it is necessary that we should eat slowly and thoroughly masticate our food. The stomach is one of the principal organs of diges- tion. It resembles a bag-pipe in appearance, having a greater and lesser curvature. It lies crosswise in the abdominal cavity below the diaphragm, but when dis- tended with food, its position is materially changed. It has two openings, one on the left side continuous with the lower end of the esophagus already referred to, and called the cardiac opening from its proximity to the heart, and the other on the right side connected THE VITAL PROCESSES 41 with the small intestines. This opening is guarded by a valve-like constriction called the pylorus or "gate keeper," which aids in preventing food from return- ing to the stomach, although in certain conditions this m.ay occur. The stomach is ten to twelve inches long, about five inches in diameter and weighs something over four imm.;!iirl!ii!!V-,ViJ„!.| M' ,1 ' ■ \ ;^ , I Fig. 10. — The stomach. ounces. Its capacity is from five to eight pints. In a newborn child it holds about one ounce. The stom- ach is composed of three coats or layers : the external, Hhroserous ; the middle, muscular; and the internal, mucous coat. The external covering supplies strength and prevents friction during the movement of the stomach. The muscular coat, composed of involun- tary muscle fibers, furnishes the movement neces- sary for the proper digestion of food, for it manipu- lates the stomach so that the food may be freely ex- posed to the gastric juice. The internal coat, or 42 GOOD HEALTH mucous membrane, is the most important layer of the stomach, for in the substance of this membrane are found innumerable little glands which open upon its surface. These are known as ''peptic" or "gastric" glands, and secrete the gastric juice necessary to di- gestion. When food enters the stomach, or even at the beginning of mastication, the contents of these glands appear on the surface of the membrane, and the muscular coat begins its slow and worm-like con- traction to bring the food into contact with this secre- tion. The food is then changed in character and be- comes a uniform mass, some of which is absorbed by the capillary blood-vessels of the stomach ; the greater part, however, passes into the small intestines for further digestion and absorption. The stomach is collapsible when empty, but when full lies against the abdominal walls and presses up- ward against the diaphragm, and in this manner often interferes with the action of the heart and lungs. The distress which commonly occurs after a full meal is usually due to this cause. The gastric juice, of which about fourteen pints are secreted in twenty-four hours, is an acid secretion, differing from all other digestive fluids, which are alkaline. The small intestine is also a very important organ of digestion. It begins at the pyloric, or right, ex- tremity of the stomach, and is a tube about twenty feet long and one inch in diameter and is composed of three coats similar to the stomach. Although there is no line of demarcation, anatomists have for certain THE VITAL PROCESSES 43 reasons divided the small intestine into three portions, the first, or duodenum, being the shortest portion — Fig. II. — Position of abdominal contents. about eight inches long. The second is called the jejunum, and the last portion is known as the ileum. The jejunum is generally empty after death and re- ceives its name from this fact. In the mucous mem- 44 GOOD HEALTH brane of the intestine are found glands yielding an alkaline secretion which plays an exceedingly import- ant part in digestion. For instance, while meats are broken up and dissolved by the gastric juice, they are digested and absorbed in the small intestine. The large intestine is about five feet long and twice the diameter of the small intestine. It begins on the right side of the body and is divided into three por- tions: the ascending, the transverse and the descend- ing colon. The lower part of the last is called the rec- tum and terminates at the external opening, or anus. The small intestine is continuous with the lower por- tion of the ascending colon. The digestive power of the large intestine is very feeble and unimportant; it is rather a temporary receptacle for undigested food and refuse matter which is to be discharged from the body. The transverse colon, which crosses the center of the abdomen about on the level with the navel, frequently becomes irritated by an accumulation of waste matter, and is the seat of intense pain known as "colic." The appendix, the inflammation of which, known as appendicitis, is familiar to the public, is a small tube about two or three inches long and about a quarter of an inch in diameter, given off from the lower end of the ascending colon. Its function is not known. The liver is the largest organ of the body. It is situated in the abdominal cavity below the diaphragm and above the stomach, principally on the right side, its longest diameter being from right to left. This organ, moderately filled with blood, weighs about four THE VITAL PROCESSES 45 pounds. The surfaces of the liver are smooth and dark brown. In its normal healthy condition it extends downward on the right side as far as the lower border of the ribs. Under certain conditions, however, such as tight lacing, it may be pressed below this point. Fig. 12. — Under surface of the liver, showing the gall-bladder and a section of blood-vessels. The liver has three distinct and separate functions: First, it renders very important aid to digestion through a certain secretion known as bile. It also pro- duces sugar which subsequently becomes changed chemically and helps to generate the body heat. Finally it removes a small amount of waste matter from the system ; in other words, it excretes as well as secjretes. 46 GOOD HEALTH The bile is discharged through a small tube into the first portion of the small intestine, the duodenum. On the under surface of the liver is found a pouch about four inches long and one inch in width, called the gall-bladder. This acts as a reservoir for the bile, the flow being continuous. The pancreas, or ''belly sweetbreads," compared with the liver is a very small gland, being about six Fig. 13. — The pancreas, partly cut away, so as to show the duct which collects the pancreatic juice and empties it into the duo- denum. inches long and one inch in thickness, but it has an exceedingly important function. It is located at tlie upper and back part of the abdominal cavity, mainly on the left side and behind the stomach. It secretes an alkaline fluid called the pancreatic juice, which is discharged through a small tube into the duodenum where the bile is also received, at which point these two important secretions act together. The chief function of the pancreatic juice is to prepare the oil and fat contained in the food for absorption by the process known as ''emulsification." During this trans- THE VITAL PROCESSES 47 formation the oil and fat of the food are converted into a whitish fluid called ''chyle," which is absorbed by the lymphatic vessels that follow along the intes- tinal tract. They are called lacteals, or milk carriers, on account of their color when filled with chyle. These empty into a pouch located in the lower part of the back, from which point the chyle is carried through a tube, the thoracic duct, to a large vein on the upper left side of the chest, and in this way reaches the circulation and forms a necessary element of nutrition. In addition to the above, the pancreatic juice has an all-round function in digestion, and as- sists other digestive fluids in their work. KIDNEYS The kidneys are excretory organs. They consist of two large, bean-shaped glands situated at the back of the abdominal cavity on each side of the spinal column, extending from the eleventh rib downward nearly to the upper portion of the pelvis, the right kidney being a little below the left. They are about four inches in length and two in width and weigh from four to six ounces each. The kidneys are constructed of tubes which may be called waste pipes, for their purpose is to drain oif from the blood refuse and poisonous matter consisting largely of worn out tissue. The fluid excreted by these organs is known as urine, and consists of water holding in solution the various products just referred to, the principal one being known as urea. If this is 48 GOOD HEALTH not promptly removed from the body serious or fatal results follow. This usually occurs in the advanced stages of kidney disease. The amount of urine ordi- narily discharged from the body in twenty-four hours is about three pints, although this is subject to great change, depending upon climatic conditions and vari- ous organic and functional affections. The urine passes from the kidneys to the bladder Fig. 14. — Vertical section of a kidney, showing the minute tubes which excrete the urine; also the pelvis, or basin of the kidney, which receives the urine before it passes downward to the blad- der. The beginning of a ureter is also shown. THE VITAL PROCESSES 49 through two small tubes, one for each kidney about the size of a goose-quill, and sixteen to eighteen inches long; these are known as ureters. Small concretions from the kidneys, popularly known as "gravel," vary- ing in size from a grain of sand to larger dimensions, often pass through these tubes to the bladder, usually causing intense pain. The bladder or reservoir which receives the urine is situated in the lower part of the pelvic cavity in front, and is a sac or pouch having three coats or lay- ers similar to the layers of the stomach and intestines. When moderately distended the bladder is about five by three inches, and usually contains about one pint, although it may hold considerably more. The mus- cular coat, consisting of involuntary, or unstriped, muscle fibers, is the principal factor in expelling the urine, although this may be aided by the action of the powerful abdominal muscles which are under the con- trol of the will. SKIN The skin covers all portions of the body and pro- tects the deeper parts, and aids in giving grace and symmetry to the body. Like the liver, it is an organ of secretion and excretion, its principal function be- ing similar to that of the kidneys. It also contains the sense of touch, which is highly developed at the finger ends. Contrary to general belief, the power of ab- sorption through the unbroken skin of the human be- ing is extremely slight. The skin is composed of two layers, the outer and 50 GOOD HEALTH inner. The outer is known as the epidermis, false or scarf skin; the inner receiving the name of derma or true skin. The epidermis contains neither blood- vessels nor nerves, and is simply a scaly layer which protects the true skin underneath, and becomes easily detached from it under certain abnormal conditions. A sunburn will show the separation of these layers often with a small amount of fluid between them which constitutes a blister. The derma, or true skin, is richly supplied with blood-vessels and lymphatics. The true skin contains millions of minute suderif- erous, or sweat, glands, sebaceous, or fat, glands and hair follicles. The sweat glands, like the ducts in the kidneys, are constantly removing from the body a watery vapor known as perspiration or "sweat," an excretion which by rapid evaporation from the sur- face has largely to do with the regulation — usually reduction — of the body temperature. This wonder- ful activity of the skin and the large quantity of per- spiration thrown off and rapidly evaporated enable one to endure a very high degree of heat. In addition to the action just described, the sweat glands eliminate from the system waste matter simi- lar to that excreted by the kidneys, chiefly urea. For this reason the skin is regarded somewhat as a sup- plementary organ to the kidneys, and they relieve each other. In warm weather when the skin is most ac- tive, the amount of perspiration is largely increased, and the amount of urine is correspondingly diminished, while in winter the condition is reversed. About two pints of perspiration is excreted in twenty-four hours THE VITAL PROCESSES 51 in temperate weather, although this may be largely increased, for it is subject to great variations depend- ing upon the outside temperature, exercise, etc. It is very important that the similarity of function of the skin and kidneys should be recognized, for when one is disabled, the other may to a certain extent perform its work. For instance, if the kidneys are impaired either temporarily or permanently, much relief may be obtained by stimulating the skin. Impairment of the function of either of these organs becomes a seri- ous matter if it is prolonged or if one does not quickly relieve the other. Physiologists have proven this by shaving and varnishing the skin of animals ; grave or fatal results soon follow.- The importance of keeping Sweat pore Epidermiia Dennis Sweat gland | - - ( j / , Oil glands WW) ' } Fat eel! Hair bulb Blood-vessel " Fig. 15. — Section of skin greatly magnified. . 52 GOOD HEALTH the skin and kidneys in a good healthy condition by a proper mode of living is apparent. The product of the fat, or sebaceous, glands which lie close to and discharge their contents into the hair sheath, or follicle, in the skin is a secretion. It pro- tects and keeps the skin, as well as the hair, in an oily and pliable condition. With few exceptions, the hair follicles cover the surface of the body, although in some portions it is so fine that it is hardly noticeable. The hair and nails are for the purpose of protection and are regarded as appendages of the skin; they re- ceive their nourishment by absorption. The experience of "hair standing on end'* is not entirely a fancy, for attached to the sheath, or folli- cle, which conducts the hair to the surface of the skin are involuntary muscle fibers which, when for- cibly contracted, raise the hair to a more erect posi- tion. This contraction may be brought about by men- tal stimulus, such as fright, etc. SPLEEN The spleen is a soft and spongy organ situated in the abdominal cavity on the left side near the stomach, and extends from the ninth to the eleventh rib. It measures about five inches long, three inches wide and two inches thick and weighs about eight ounces. It is called a ductless gland, not having the characteris- tic of either a secretory or excretory organ. Its func- tion has not yet been definitely settled, although it is not absolutely essential to life, for, as a surgical neces- sity, it has been removed from the body with recovery THE VITAL PROCESSES 53 of the patient. Under certain conditions it becomes inflamed and enlarged; for instance, in malaria the spleen becomes very much increased in size, and in sections of the world where this disease is prevalent the enlargement, which is quite apparent, is referred to as "ague cake," the term ague meaning malarial fever. NERVOUS SYSTEM The activity of the mind and body, the harmonious working of the several organs, and the sympathy exist- ing between the different parts of the body depend upon the nervous system which is divided into the cerebrospinal axis, or central nervous system, and the sympathetic system. The cerebrospinal axis comprises the brain, the spinal cord and the nerves. The brain, which is the seat of the intellect, the will and the emotions, is contained in the cranial cavity. It is divided into four principal parts : the cerebrum, cerebellum, the pons Varolii and the medulla oblongata. The cerebrum constitutes about four-fifths of the entire brain. It is egg-shaped or oval in form and is divided into two portions by a deep groove running from the front backward. It is composed of gray mat- ter and white matter and is about the consistence of sweetbreads. The white matter forms the internal and greater portion of the cerebrum, the gray matter form- ing the external layer. The surface of the cerebrum is not smooth, but is thrown into deep folds called con- volutions ; this arrangement increases its area, and consequently its function. These convolutions are not Fig. 1 6. — The cerebrospinal system of nerves. 54 THE VITAL PROCESSES 55 well marked in the brain of an infant, but grow deeper and larger until this organ has practically reached its full development at about the fortieth year. The deep convolutions referred to are characteristic of the Fig. 17. — Side view of the brain. human brain; they are present in a far less degree in the lower animals. The cerebrum is the seat of the mind and its func- tions which distinguish man from the lower animal. The exact points in the cerebrum where these vari- ous functions are located have not yet been fully determined, although there is no doubt that they are connected with the gray matter. The cerebellum, or little brain, corresponds in struc- ture closely to the cerebrum with which it is connected, being situated beneath it and at the back part of the 56 GOOD HEALTH cranial cavity. The cerebellum regulates and keeps in perfect harmony the different movements of the body, particularly the extremities. Cerebrum. Pons Varolii, Medulla oblongata. Cerebellum. Fig. 1 8. — Under surface of brain, showing the cerebrum, cerebellum, pons Varolii, and medulla oblongata. The pons Varolii, or "bridge," is the small portion of the brain situated in front of the cerebellum; it binds together the different parts of the brain already enumerated, and also transmits the different nerves passing between the brain and the spinal cord. THE VITAL PROCESSES 57 The medulla oblongata is beneath the pons Varolii, and appears to be the upper end of the spinal cord somewhat extended. In the substance of the inedulla, nerves which supply motion, passing from the brain to the spinal cord, cross each other, or decussate. Con- sequently, a motor nerve fiber having its origin in the right side of the brain crosses to the left when it reaches the medulla, and therefore becomes identified with the left side of the spinal cord from which point it supplies motion to the same side of the body. This will explain why a hemorrhage on one side of the brain will produce paralysis on the opposite side of the body, as in apoplexy. The medulla also presides over the function of respiration. The human brain weighs about fifty ounces, being heavier than that of any lower animal, with the ex- ception of the elephant and the whale. The spinal cord is that portion of the central ner- ^^ous system contained in the spinal or vertebral col- umn. The cord is cylindrical in shape, extending downward from the brain to the first lumbar vertebra ; it is from fifteen to eighteen inches long. Through its branches it transmits nerve impulses to and from the brain. It is to a certain extent capable of acting as a separate nerve center and generating force independ- ently of the brain, as far as motion and sensation are concerned, but not special sense. Nerves are classified as those having a motor in- fluence, those having sensory influence, and nerves of special sense. Motor nerves are fibers which conduct from the 58 GOOD HEALTH brain, and to a certain extent from the spinal cord, the force necessary to animate muscular fiber, thus pro- ducing the different movements of the body. Motor nerves, therefore, transmit an influence from within outward. If wt desire to walk, the mind wills that certain muscles shall be put into action ; this communi- cation is transmitted from the brain through the motor nerves in the spinal cord to the muscles. In the ordi- nary movement of the body we do not direct the ac- tion of each muscle, for this is done mechanically; but the mind starts and stops the machine and directs its course. Sensory nerves are fibers which convey sensations from the different portions of the body to the brain from without inward. For instance, when a finger is burned or injured, the sensation of the pain experi- enced indicates the impression made upon the sensory nerve at the point of injury and communicated to the great nerve center or brain. There are thirty-two nerves given off from each side of the spinal cord, forming thirty-two pairs. Each pair of nerves contains motor and sensory filaments or fibers which are distributed to the body to perform the function already described. Nerves of special sense, as the name implies, have a separate function from those referred to above. They do not transmit motion or common sensation, but preside over the special senses, such as sight, hear- ing, taste, etc. Twelve pairs of nerves are provided from the under surface, or base, of the brain for this purpose. THE VITAL PROCESSES 59 The central nervous system controls the functions of animal life, the intellect, general sensation, motion and the special senses. There is still another system comprising the sympathetic nerves, which presides over secretions and excretions, the proper distribution of blood and nourishment to the tissues, the control of the involuntary muscle fibers in the alimentary tract, blood-vessels, stomach, bladder, etc. These must be unaffected by outer conditions. Were they sub- ject to the will and to the influence that governs the cerebrospinal axis, the functions of organic life would soon be disturbed and the most serious consequences would follow. This system must work uninterruptedly in health and disease both day and night and at all times. For this purpose, nature has supplied a sepa- rate and independent nerve force, the sympathetic, or ganglionic, system, consisting of a series of little bod- ies or ganglia which begin at the under surface of the brain and continue downward on each side of the spinal column to its lower extremity. Although this system is independent of the cerebrospinal axis and its special function, it communicates with and accom- panies the cranial and spinal nerves to the various organs. In this manner, the sympathetic system brings the different organs into sympathetic relation with each other. This relation will explain why a disordered stomach will produce headache and why death may follow a severe blow at the pit of the stomach. In the latter event the large sympathetic ganglion at the back of the stomach is injured and the shock conveyed to the heart is sufficient to arrest its action. 6o GOOD HEALTH • LYMPHATIC SYSTEM A description of the circulation and the means by which nourishment is supplied to and waste matter re- moved from the body would be incomplete without a reference to the lymphatic or absorbent vessels. It has been stated in an early part of this chapter that the tissues are directly nourished by the minute capillaries which have an exceedingly thin coat through which the fluid portion of the blood containing sustenance readily escapes into the surrounding tissues. After the nourishment is extracted much fluid remains and were it not quickly removed the tissues would be overcharged with fluid and become *'soggy." It is true that the capillary blood-vessels reabsorb some of this liquid but only a small part of it; therefore some other agent for this purpose is necessary : This is the function of the lymphatic vessels. These ves- sels begin close to the capillaries and coming together form larger vessels which, with the exception of those draining the right arm and the right side of the face and neck, discharge their contents into a common trunk known as the thoracic duct. The thoracic duct lies in front of the vertebral column and, passing up- ward, discharges its contents into a large vein on the left side of the neck ; this empties into the left auricle of the heart. The lymphatics from the right arm and right side of the face and neck empty into a cor- responding vein on the right side of the neck. There are two sets of lymphatics : a superficial one just under the skin, and one which drains the cavities THE VITAL PROCESSES 6i and deeper structures of the body. In the course of the lymphatics and intimately connected with them are found small bodies of varying sizes known as lymphatic glands. These have a very important func- tion ; they constitute a filter or trap which prevents the passage of infectious or poisonous matter into the system. In doing this they often become inflamed and enlarged and sometimes a surgical operation is neces- sary. The enlarged glands in the neck which accom- pany diphtheria or other throat affections are familiar to all. In describing the pancreas it was stated that the fats and oils taken with the food were emulsified by the pancreatic juice and transformed into a product resembling milk and known as **chyle." This is also taken up by the intestinal lymphatics and carried to the thoracic duct and thence to the general circula- tion for nourishment. It will thus be seen that the principal function of the lymphatics is to return to the circulation fluid which was removed during the process of nourishment. CHAPTER III AIR We live in a sea of air or atmosphere which sur- rounds the earth to a depth of many miles. The com- position of this aeriform envelope was unknown until about the middle of the eighteenth century, when the researches of Joseph Priestley, an English chemist, led to the discovery that air consists chiefly of oxygen and nitrogen. It was subsequently found that a very small amount of carbon dioxid, commonly known as carbonic acid, forms part of the atmosphere. The following are the proportions : nitrogen, over 79 per cent ; oxygen, over 20 per cent, and carbon dioxid, less than i per cent. These gases exist in the air as a mechanical, and not a chemical, compound. In addition, a varying amount of moisture is always found in the atmosphere. Air also contains impurities, either gases or solids, which differ in character and amount according to the locality, the purest air being found at sea and in the mountainous regions. The composition of air and the fact that the propor- tion of the gases which compose it is subject to very little change call for more than passing notice. It is with oxygen we are chiefly concerned, for of this we must have a constant supply to maintain our existence. 62 AIR 63 Oxygen is far too stimulating to be used alone, for under this condition we would soon be worn out from overexcitement. Therefore, nature dilutes it with ni- trogen, a very bland and inactive gas. For this reason it is of great importance that the normal proportion of gases composing the air should remain undisturbed. Carbon dioxid is found even in the purest air. This gas is the result of innumerable forms of decay upon the earth's surface, and also within the earth. It is not injurious to health in the proportion in which it exists in good outside air, but when there is an exces- sive amount present, due to some form of contamina- tion, particularly within doors, unpleasant or serious results may follow. The moisture which is more or less constantly pres- ent in the air is due to the invisible vapor which rises from the great bodies of water upon the earth's sur- face and which returns in the form of mist, rain and snow. Through the respiratory tract the air reaches the lungs, where a vitally important interchange takes place. Here about one-fourth of the oxygen contained in the air entering the lungs is extracted for the pur- pose of enriching the blood, to renew the worn out tissue of the body and to produce heat. In exchange, carbon dioxid and other products representing waste matter are thrown off with the expired air. The inter- change referred to takes place in the minute air cells which have been described in the preceding chapter. In connection with this part of the subject it is very interesting to note that while animals absorb oxy- 64 GOOD HEALTH gen and give off carbon dioxid as a waste product, plants depend upon carbon dioxid for their growth, and liberate oxygen. It is largely by this means that the proper proportions of these gases in the air are maintained. Impure air is found within and without the house. Outside the usual sources of contamination are the va- rious industrial occupations — particularly where coal is used in large quantities, the combustion of which gen- erates gases injurious to health — too closely con- structed buildings, narrow and filthy streets and vari- ous forms of decomposing matter. Nature goes far to neutralize these conditions by oxi- dation, by winds which rapidly displace or change the air and freshen it and by rains which wash or carry down all sorts of contamination. We recognize the improved condition of the air after a storm. Sunlight and vegetation are also important factors in securing this result. The law of diffusion of gases by which the latter mix with or work through each other is an exceedingly im- portant factor in our protection, for if it were not so, the heavier or poisonous gases would lie close to the surface of the earth, and our life would be very brief. Within a building the sources of impurities are the exhalations from the lungs, mouth and skin of those present, dust, filth, improper ventilation, bad plumb- ing and other insanitary conditions. In factories and mines there are, in addition to these impurities, prod- ucts arising from particles of coal, stone, metal, and poisonous gases, which are largely responsible for the AIR 65 diseases commonly found among the workers in these places. Air is carried into the soil and when mixed there with decomposed organic matter, becomes un- healthful and offensive. Poisonous and inflammable gases are also generated beneath the surface and may be found at a considerable depth. When excavations are made, or during mining operations, they are fre- quently released and are not only detrimental to health, but when exposed to a flame or the oxygen of the air may cause explosions. Carburetted hydrogen or ''fire- damp" is an illustration. Contamination from underground sources is not in- frequently the cause of unhealthful and offensive cel- lars, for their walls, particularly those in the country, are often improperly constructed and may permit un- derground gases to pass through. These not only cause unpleasant odors, but are likely to contaminate milk and other foodstuffs which may be present. These gases may also permeate the house. It is not difficult to understand why those who work in mines or places where the air is contaminated are frequent victims of tuberculosis. In marked contrast to this is the fact that those who are most free from this disease are farmers and fishermen whose occupa- tions keep them constantly in the open air. There is a popular belief that impure air may be the origin of infectious diseases. This i^ not true. The danger of impure air lies in the fact that it lowers the resisting power of the body and renders it more sus- ceptible to disease. However, this only occurs where there is a long continued exposure to polluted air. 66 GOOD HEALTH Modern sanitation has brought about a more serious realization of the necessity of pure air both to the sick and the well. Physicians have studied its importance in disease, and the windows of sickrooms are no longer kept closed. Certain affections, especially tuberculosis, are often treated in the open air with most satisfactory results, and medication in these instances has to a great extent been discarded. Sleeping in the open air is now a common practice and those who adopt it under proper and reasonable conditions discover its stimulating and invigorating effect. Fresh air is therefore a tonic both in health and sickness, and a powerful factor in com- bating disease. While we cannot expect to find absolutely pure air, for the air we breathe contains some form of contam- ination, we should seek for good fresh or moving air, and also remember that it is the maximum and not the minimum that is desired, and that this can only be found out of doors. The belief that night air is detrimental to health has little or no foundation. Ozone is a modified form of oxygen. Its existence in the lower stratum of atmosphere, except under spe- cial or local conditions, has not been definitely proved. It is generated during thunderstorms as the re- sult of the action of electricity in the air, and it is often present in the immediate vicinity of an electric appa- ratus. At these times it may be recognized by its peculiar odor, which somewhat resembles that of rub- ber. The popular notion that ozone is a great purifier has been responsible for many theories concerning its healing properties in connection with certain diseases. AIR 67 The fact that comparatively little investigation has been made in regard to the use of this gas for practical purposes furnishes meager information as to its pos- sibilities. Ozone is artificially produced by electricity for commercial and disinfecting purposes. It is a much more powerful oxidizer than oxygen. It bleaches, and is destructive to bacteria. The term humidity relates to the moisture contained in the air. Sometimes the amount is very great during the summer and goes far to increase the uncomfort- able and depressing effect of the hot weather. The regulation and cooling of the body temperature de- pends largely upon the proper evaporation of the wa- ter or perspiration discharged upon the surface of the skin. This takes place much more rapidly when the air is dry than when the air is very humid. There- fore, if the atmosphere is well saturated with water, less heat is given off from the body, and the physical effect is far more uncomfortable and oppressive. It is for this reason that high localities are sought for during the hot season, for in these places the humidity is usually lower and the air is correspondingly dry and bracing. Agitation of the air cools the body by causing more rapid evaporation from the skin. Therefore, electric fans used during the warm weather have a very grate- ful and beneficial effect, provided they are properly situated in the apartment and not too close to its oc- cupants. Otherwise, they may have the effect of drafts. A very important and interesting' part of the sub- 68 GOOD HEALTH ject of atmosphere relates to its weight. The weight of the atmosphere is equivalent to about fifteen pounds' pressure upon every square inch of surface at the level of the sea. This pressure has an important effect as far as the human body is concerned, for it main- tains the equilibrium of the heart's action and the cir- culation of the blood. When a high altitude is reached this control is somewhat lessened as the weight of the air is diminished and the heart is apt to become dis- turbed and very small blood-vessels, particularly those in the mucous membrane of the air passages, frequent- ly burst. Nose bleed often takes place under these conditions. These occurrences are familiar to travelers who ascend lofty mountains, and are usually unattend- ed with danger, unless some serious organic disease of the heart or blood-vessels exists. It should be noted that this is not due to a change in the proportion of the gases composing the air, but to the lessened density of the atmosphere. The pressure of the air affects not only the earth's surface, but also every object upon the earth. There- fore a man of ordinary size probably sustains a weight of fifteen or sixteen tons. The question very naturally arises : Why are we not crushed by this enormous pressure? It is because it is equally distributed and because there is air in the tissues and cavities of the body which presses outward. These conditions bring about an adjustment, prevent interference with the various functions and render us unconscious of any pressure ; yet when the air is in rapid motion, as dur- ing windstorms, we can appreciate its force and power. CHAPTER IV WATER Chemically pure water consists of two volumes of hydrogen and one of oxygen. We do not drink pure water, for the natural supply always contains vari- ous salts as well as some form of contamination. Some of these salts are necessary for our well-being, and the contamination which occurs in good healthful water, which may be termed practically pure, is so slight that it may be regarded as a negligible factor. The chief danger from potable water lies in the fact that it may contain infectious germs. Water, next to air, is most necessary to our ex- istence; without it we could live only a few days. It plays an exceedingly important part in maintaining the functions of the organs and tissues, and forms at least four-fifths of all the food we take. It is constantly needed to make up for the loss of moisture from the skin and lungs, and also aids in preserving the shape and symmetry of the body which is composed of sev- enty-five per cent of water. Water supplies life to plants and to all living things beneath its surface through the oxygen it contains. Fish removed from it quickly die of suffocation. Their respiratory apparatus cannot take oxygen from the air, 69 70 GOOD HEALTH although they abstract it from the water, which we are unable to do. A person who is submerged for more than four or five minutes is not usually resusci- tated. The ocean, which covers more than three-fourths of the surface of the globe, is the natural source of our water supply. From it arises, through the action of the sun's rays, a continuous invisible stream of va- por to the atmosphere. This is afterward condensed and precipitated in the form of mist, rain and snow. At least three-fourths of this returns directly to the ocean, while the part falling on the land forms rivers, lakes or pools or, penetrating into the earth, becomes the great underground system upon which we depend largely for drinking purposes. It is important to know something of the course taken by the water entering the ground and the vari- ous combinations it forms during its descent. A sec- tion of the earth will show the soil arranged in various layers or strata. The significance of this as indicating the formation and age of the earth is well known to the geologists. It is also of great interest in connection with the underground water system, for it explains the manner in which it is collected and distributed. The layers referred to are variously composed of sand, gravel, chalk, clay and other like substances. Some of these^ clay for instance, are practically im- permeable, i. e., water cannot pass through them. On the other hand, sand is easily penetrated. Therefore, water in its descent passes without difiiculty through the sand and upon reaching a layer of clay or some WATER 71 other impermeable stratum is directed along until it finds an exit somewhere. This may occur in the form of a spring or as a supply to some body of water, or it may remain below until an outlet is made for it in the form of a well. The strata found at various levels are not uniformly arranged and are frequently curved, sometimes form- ing large underground basins. As a result, water upon entering the earth may reach an impermeable stratum at different depths and supply superficial or deep wells. Innumerable forms of impurities are carried into the ground by the surface water. Many of these are filtered out by the soil; some are destroyed by oxida- tion, for air passes into the ground; and some are de- stroyed by certain forms of bacteria or germs which live upon organic matter. For this reason water be- comes purer as it goes farther into the earth, and we may expect to find a better and safer water supply in a deep well than in a superficial one. Certain gases confined in the earth sometimes force underground waters to the surface, although this is usually brought about by the pressure of the water from behind in its efforts to reach its own level. A supply frequently has its origin in mountainous regions, or where there is considerable elevation, and may follow along impermeable strata, sometimes to a con- siderable depth, and appear at the surface by natural or artificial agencies many miles away. Not infrequently heated water, which probably has its origin in the earth, reaches the surface and forms what are known as "hot springs." The various condi- ^2 GOOD HEALTH tions above referred to have led to the establishment of many celebrated resorts, water cures and springs throughout the world. Water is one of the most important of solvents, and during its transit through the earth, various chemical changes take place. The soil is rich in carbonic acid, and the underground water, holding this gas in solu- tion, dissolves out various mineral substances con- tained in the strata with which it comes in contact. In some instances, the presence of these salts is so pro- nounced that the water is unfit for general use, al- though in this condition it is sometimes employed for medicinal purposes. Water most frequently combines with lime and magnesia, particularly the former. When a comparatively large amount of it is present, the water becomes ''hard," i. e., the lime or magnesia com- bines with the fatty acids of soap and prevents the prompt formation of lather. For this reason, the hard water is neither satisfactory nor economical for bath- ing or domestic purposes. While it is believed by some that the long continued use of hard water for drink- ing purposes may cause certain affections, it is prob- able that there is little danger from this source pro- vided the water is not too hard, although it may not be as palatable as some other kind. Water which contains little or no Hme is called ''soft" and is better and pleasanter for general use. If it were possible to collect rain water above the point of contamination, it would be the purest and softest supply we could obtain ; but during its descent, some form of pollution always takes place, for it WATER 73 washes out the air. In the country the contamination is comparatively sHght, but in cities and manufacturing towns, where the air is constantly charged with poison- ous gases, products of offensive trades and the usual pollution of these places, the rain water, unless puri- fied, is usually unfit for drinking purposes. In regions where there is no general water supply to draw from, such as springs, rivers, lakes, etc., and where little can be secured from underground sources owing to the peculiar formation of the soil, rain water is carefully and eagerly collected. In emergencies it is often caught upon canvas or rubber cloths, and for general use large ground areas with cemented floors and underground storage cisterns are sometimes em- ployed. Although the more common method is to col- lect it in receptacles as it runs from the roofs of build- ings. As a rule, little attention is given to the clean- liness of these surfaces, yet it is of great importance if the water is used for drinking purposes. A meas- ure of protection against contamination may be se- cured by having the waste pipe from the roof so constructed that it can be quickly disconnected from the storage tank or barrel at the beginning of the rain and allowed to discharge over the ground for a few minutes in order that the roof may be cleaned, and then reconnected with the receptacle. A high- pitched slate roof offers the best advantages so far as this form of rain water collection is concerned; it is much easier to clean. Careful attention should be given to the construc- tion of storage tanks or cisterns. They should not be 74 GOOD HEALTH made of lead, for rain or other soft water will dis- solve the metal and render the water unfit for drinking purposes. For the same reason lead pipes should not be used for the transmission of drinking water. Iron tanks may discolor the water and also make it un- pleasant for drinking. These tanks should be con- structed preferably of Portland cement, slate or enam- eled ware, which gives off no objectionable product and can be cleaned easily and promptly. Galvanized iron may be used, although it is inferior to the ma- terials just referred to. Wood is commonly used for the construction of storage tanks, particularly on the tops of buildings where it is necessary that the weight of these receptacles should be reduced to the mini- mum. The objection to it is that it rots and leaks, ab- sorbs unpleasant odors and cannot be properly cleaned. A storage tank should have an outlet at the bot- tom which will permit the free escape of its contents in order that it may be properly cleaned. For cleaning there is no better agent than a solution of soda and hot water applied with a long-handled brush ; the tank afterwards should be carefully rinsed out. The brush should be boiled in water for at least five minutes immediately preceding its use, to destroy any bacteria which may be present. If the tank is of a very large size, it is a common practice for the cleaner to go inside the receptacle. Infective material is in this way undoubtedly transmitted by the feet. If this method is employed the cleaner should wear rubber boots, which have just previously been heated in boiling water. WATER 75 Underground tanks for the storage of water are to be condemned under all circumstances. If improperly constructed, they are not only liable to admit poison- ous gases from the surrounding soil, but are subject to all sorts of surface contamination. Besides, when not efficiently covered, small animals not infrequently fall into them and are drowned. Like all tanks, they are favorite breeding places for mosquitoes. Further- more, this class of tanks cannot be properly cleaned. The demand for modern methods of waste disposal in country homes, which is referred to later on, calls for the construction of storage tanks on the roof or in the top floor of the house. These should have a capacity of about five thousand gallons for drinking, flushing and other purposes. These tanks should be closed with a tight-fitting cover and ventilated by a pipe from the cover to the outside of the building, which should have a bend in order that foreign bodies cannot reach the contents of the tank. Rain water barrels found about country homes are usually in an unsanitary condition and imperfectly covered. They also serve as breeding places for mos- quitoes. This is so notorious that the common torm of this insect is known as the "rain-barrel" mosquito. Spring water is usually cold, sparkling and re- freshing, and therefore very palatable. Spring water may be quite free from impurities in the country, but in towns and cities there is always danger of contami- nation, for the water may come through superficial strata and receive impurities from the surface. When spring water is used, it should be protected against 'jd GOOD HEALTH contamination at its exit by a stone or cement walls and floor. In addition, a pipe may be introduced into the opening, not only for protection but to conduct the water more effectively to its exit. Lake water, particularly from the mountain slopes, furnishes a very satisfactory drinking supply, for it is relatively pure. The water is still and the organic matter and other forms of impurities which it contains easily settle to the bottom; moreover, oxidation goes far to destroy impurities on the surface. There is considerable truth in the saying that lakes clean them- selves. When this supply is used for drinking pur- poses, there should be the most rigid and constant con- trol to prevent the discharge of sewage or other forms of filth into the water, and the intake should be some distance from the shore to prevent still further the danger of contamination. The safety of this form of water supply must always be seriously ques- tioned if the border of the lake is inhabited. River water, which is often used as a general water supply, is very apt to be unfit to drink except at its head in rriountains and tributaries which are not con- taminated, or before it receives the waste and sew- age of towns. The ease and economy with which municipalities can draw water from these sources have led to many serious results as far as general infection is concerned. River water used by large communities for drinking purposes is generally filtered or otherwise treated for the purpose of purification. The former method usually consists, in brief, of passing the water over WATER y-j filter beds composed of gravel on top of which is a layer of fine sand three or four feet in depth. Impuri- ties are removed as the water passes down through the permeable layers to its destination or receivers. If this method is properly carried out the intake is largely freed from bacteria and other forms of con- tamination. The important protective factor in this process is the sand, although a scum or layer, ex- tracted from the water, which forms on the top of the sand, also acts as a filter and is of value as a puri- fying agent. This means of purification, however, cannot be de- pended upon and river water for drinking purposes in inhabited regions is always a menace to the public health. The ancient Romans were aware of this, for although the River Tiber runs through the City of Rome, water was brought from distant sources by aqueducts so splendidly constructed that some por- tions are still in use. Well water is a common source of supply in this country, and, like spring water, is cool and pleasant to drink. Unfortunately, wells are frequently contami- nated, and in this way may convey infectious ma- terial; for instance, typhoid fever is sometimes trans- mitted by this means and partly explains why this dis- ease often occurs in rural districts. Deep wells are less dangerous as far as infection is concerned than superficial ones, for the water from the former is usually drawn from a deeper stratum; yet defective construction will allow surface impuri- ties to reach the interior of even deep wells throug^h 78 GOOD HEALTH their walls. Artesian wells constitute an exception to this, for they are sometimes bored to a depth of many hundred feet to reach below or between imper- meable strata where water is held under pressure. This escapes to the surface through a continuous pipe or tube which if properly constructed admits of but little danger from contamination, particularly if the exit is carefully protected. For this reason, arte- sian well water may often be used with safety in built- up communities, although in all instances they should be under the observation of health authorities. There is need of protection about the opening of an ordinary well, as the space immediately surrounding it is often a fruitful source of contamination, and for a distance of a few feet at least this should be graded and cemented from the edge of the wall outward and downward. The open or ''old oaken bucket" system is anything but sanitary. In its place a modern pump- ing apparatus should be used so that the opening of the well can be closed and protected against pollution and the entrance of small animals. The ordinary dug well is cylindrical and is usually lined with brick or stone and cement. The safety of this means of water supply is greatly enhanced if the outside of the wall or structure of the well is tarred. As a well may receive infectious matter from a nearby broken drain or privy vault, cesspool or the like through the soil, it is necessary in addition to the proper construction that it be placed at the highest practicable point and as far as possible from all chance of pollution. A safe distance cannot be arbitrarily WATER 79 stated, for the danger of infection depends largely upon the arrangement of the underground strata. However, a well may be placed fairly out of harm's w^ay by a careful study of the conditions already re- ferred to. The danger of contaminating a well from surface drainage is probably much exaggerated, yet it may occur where fissures or cracks exist in the grounds. It is a practice among those who frequently make short excursions into the country to drink clear cold well water whenever it can be found. This is un- safe, particularly where the wells are not in constant use. Water from this source should not be used for drinking purposes unless after careful inquiry and ob- servation there is reasonable evidence that it is not contaminated. Some form of infection might be the result of omitting this precaution. The ova, or eggs, of various parasites, such as the tapeworm, hookworm, and roundworm, which are ex- pelled from the intestinal tract, may reach a water supply. Not infrequently small streams or creeks, which furnish water cool and pleasant to drink, are contaminated through sewage which empties into them. Therefore, water from these streams should not be used for drinking purposes, nor should the wa- tercress or other vegetation which grows in them be eaten unless there is substantial proof that there is no pollution present. The need of water in the preservation of health is far from being appreciated and as a rule we do not drink enough of it. A lack of water often leads to 8o GOOD HEALTH indigestion, torpidity, constipation, headache, dryness of the skin, etc. It is estimated that the adult human being requires about two quarts of water within the twenty- four hours. One-third of this is usually taken in with the food. "In addition, four or five glasses during the day under ordinary conditions would be a fair estimate of the amount required by the system. It is subject to great variations, depending largely upon exercise and climatic conditions, for during the warm weather the activity of the skin rapidly abstracts large quanti- ties of water from the body which should be promptly replaced. Contrary to the general belief, there is no objection to drinking a reasonable amount of water with meals, although it should not be confined to this time but distributed more evenly throughout the day. It is not harmful to drink moderately of iced water, particu- larly during the warm weather, for it aids in cooling the body. It may be added that horses under ordinary conditions drink about eight gallons of water daily and cattle somewhat less. The importance of water in maintaining health re- quires that the supply shall be as pure as possible. We shall learn as we go further into the subject that nature does not demand, that what we eat and drink and the air we breathe shall be absolutely pure, for it is tolerant of a certain amount of adulteration. Some form of impurity almost always exists, particularly in municipal water supplies. The danger is not so much from ordinary contamination but rather from the WATER 8t presence of infectious germs which are not apparent from the appearance, for the clearest and apparently purest specimens of the water may contain germs of disease. It is reasonable to assume that if there is no marked prevalence of water-borne diseases, such as typhoid fever and dysentery, the general supply of a town or city may be drunk with safety. Reliable information regarding this matter may usually be obtained from the local health officer. It is a common practice, even in cities and towns where the safety of the general water supply has been reasonably established, to drink bottled waters for the alleged purpose of escaping infection. This practice not only inspires fear but is usually without justifica- tion and should not be resorted to unless in some special instance it is recommended by the municipal health authorities. Furthermore, there is doubt as to the purity of some of the bottled waters offered for sale. There are many methods proposed and innumerable types of water filters offered for sale for the clarifica- tion and purification of drinking water, chiefly for domestic purposes. A large percentage of these filters find their way to country homes in response to a demand for some appliance or means which will afford protection against contaminated water. While not attempting to discuss the relative merits of the various filters, it may be said that some render very efficient aid in the purification of water, but a large proportion of them are practically worthless. 82 GOOD HEALTH Furthermore, the public does not as a rule seek proper advice in the selection of these apparatus, but are quite willing to accept the very plausible recommendation of their makers. The home practice of clarifying water by the use of alum, tea leaves, etc., is not entitled to considera- tion, for it is worse than useless. It suggests a pro- tection which is only imaginary, for these methods do not destroy infectious organisms which may exist in the water. In small communities and in the country where no properly organized health protection exists one should be particularly alert in guarding against impure drink- ing water. This may be done by carefully bearing in mind the way in which water supplies are collected and the ordinary means of contamination. But fur- ther and still more important is the need of a periodical bacteriological examination of all drinking water which is not a part of a general or common supply and un- der the careful observation of municipal health au- thorities. Moreover, such an examination should be made whenever there is suspicion of contamination. There is no filter or domestic remedy which may be safely accepted as a substitute for this. This is in line with modern sanitation and not an impracticable procedure, for it is quite probable that every State in the Union as well as every city is equipped with laboratory facilities where water and other suspected fluids and solids are examined free of charge. Be- sides, the means of communication throughout the country are now so extended and rapid that even in a WATER 83 remote section a report may be obtained within a com- paratively short time. In addition there are many pri- vate laboratories located throughout the country where such examinations are made for a small fee. A de- creased mortality would furnish proof as to the value of this means of public protection. There are, of course, many instances where a lab- oratory report cannot be obtained promptly and the exigencies of the occasion demand that some immedi- ate action be taken to protect the community against a presumably contaminated water supply. Fortunately there is a means which is unfailing in its action, always available and practically without cost; that is, the ap- plication of heat by boiling the water. By this means all disease-bearing germs which affect human beings are promptly destroyed. To accomplish this water should be continuously boiled for at least five minutes ; simply bringing the water to a boiling point does not always answer the purpose. Boiling renders the water somewhat flat to the taste as the air which it contains is expelled by the heat. This may be overcome by aeration, or by agitating the water in an ordinary churn which is known to be clean^ or letting it escape through a receptacle containing numerous little holes in order that it may be finely divided and better combine with the air in its descent to another receiver. It is far safer, while the emer- gency exists, to drink the water as it is boiled rather than employ means which through carelessness may again infect it, unless some person in the house is aj>- pointed personally to take charge of the work. l^ GOOD HEALTH One of the dangers of traveling by sea in the past was due: to the contamination of drinking water on chipboard. This supply was carried in casks or tanks which were often in a filthy condition, and through •carelessness infectious germs were not infrequently in- troduced into these receptacles and diseases transmitted to those on shipboard. Now all war vessels and the .great ocean passenger steamships have distilling appa- ratus on board which render sea water fit and pure for drinking purposes in an inexhaustible amount. There is no doubt that in the future this method of 'Obtaining water free from contamination will be greatly •extended. In connection with the subject of water, it is proper •that some reference be made to ice. It is a common belief that infectious organisms existing in water are destroyed when freezing takes place. This does not .always occur, for some special organisms survive the reduction of temperature. This has been proved in the case of the germs of typhoid fever. Although natural ice may be obtained from sources ivhere there is no serious contamination, it is well Icnown that it frequently comes from bodies of water which receive sewage from large towns. To what ^extent ice under these circumstances becomes involved, it is, of course, impossible to determine, although the danger from this source is largely overestimated. In guarding against the danger from impure ice it would seem practica} and logical to use the kind of ice which so far as we can ascertain is least harmful. Ar- tificial ice is more apt to be pure, for it is usually made WATER 85 from distilled water. It is sometimes stated that it is rendered unsafe by the ammonia used in its manufac- ture. That is not so, for the ammonia does not come in direct contact with the water, but is confined in pipes, and used simply for freezing purposes. The more common danger from ice relates to the careless manner in which ice is stored and conveyed from the storehouse to the table. This may constitute a very fruitful source of contamination. Unfortu- nately, this receives but little attention from the public. CHAPTER V FOOD Food has been likened very properly to the fuel which supplies an engine with motive power. Food generates heat and energy and by this means keeps the body in a state of activity. But food in addition to this is required to replace worn out tissues and furnish nourishment for increased growth. Scientists have determined the composition *of the human body and the character of the food best suited for its support, and were it possible to give directly to the various tissues the material most needed for their sustenance, as well as substances best suited for the generation of heat and energy, the problem of nu- trition would be easily solved ; but the food we eat is subjected to the processes of digestion and assimila- tion and therefore reaches its destination in a changed and roundabout way. Still, the knowledge we possess of these processes enables us to do much toward se- curing the desired results. For instance, we have learned that bone is composed of animal and earthly matter which furnishes elasticity and strength. Bone, therefore, must be supplied with food suitable for maintenance of both of these ele- ments ; if not, trouble is quite sure to follow. If there 86 FOOD 87 is not enough earthy matter present in the form of lime, the bones are liable to become bent and distorted, particularly in the lower extremities which support the weight of the body. This frequently takes place in rickets, a disease which not uncommonly affects chil- dren. On the other hand, the muscular system, which renders the body capable of the freest movement, re- quires a different kind of food to maintain its integrity. Then, again, the secretion-producing organs of the body which have most important functions to per- form, must be provided with plenty of water, various salts and other materials from which to manufacture their special product. NUTRITION At the risk of entering a more technical field, some space will be devoted to the consideration of the vari- ous groups of food, the terms which are used to dis- tinguish them from each other, and their relative value as tissue builders and generators of heat and energy. Food is classified as organic and inorganic. Organic substances consisting of animal and vege- table matter are subdivided into those which contain nitrogen and those which do not. The organic nitrogenized foods are known as pro- teins, a word which means ''the most necessary food." This class of food is truly necessary, for the nitrogen contained in it is required in the construction of new and the repair of old tissues and in the proper nour- ishment of the body. Without it we could live but a short time. Nitrogen used in this way is taken 88 GOOD HEALTH into the system in the food and not in connection with the air we breathe. The function of nitrogen in the air, as we have already learned, is chiefly mechan- ical, for it dilutes the oxygen which otherwise would be too stimulating for respiration. Some of the more common and well known forms of proteins are meats, the albumen or white of egg, the casein of milk and the gluten of flour. The chief function of proteins is the building and repair of tis- sues, muscle for instance. They are also used to a certain extent in the generation of heat. The organic non-nitrogenized food, as the name im- plies, contains no nitrogen. It occurs in the forms of su- gars (carbohydrates) and fats. Starches, which through various sources form an exceedingly important part of our diet, are also included with the former, for during digestion they are transformed into sugar, the form in which they enter the system. The organic non-nitro- genized substances are not concerned in tissue building, but are heat and energy producers, and therefore im- portant agents of nutrition. Fat has also a mechanical function. It is deposited immediately under the skin as well as in the deeper ■structures. As it is a poor conductor of heat and cold, it aids in retaining the warmth of the body and pro- tects against the cold from without. Fat is also found over parts exposed to pressure, where it acts as a pad or protector against injury. Furthermore, it goes far towards maintaining the symmetry and beauty of the body. Both organic nitrogenized and non-nitrogenized sub- FOOD 89 stances in supplying nourishment and energy lose their identity, i. e., they become changed in character, and are not recognized in the waste matter expelled from the body through the intestinal tract, kidneys, lungs and skin. Ino7'ganic substances consist of water and various salts, for example, common salt (sodium chlorid), lime, soda and magnesia. These are necessary to maintain life. Everyone who has lived in the country is familiar with the importance of supplying cattle and other livestock with sufficient salt; if deprived of it, they generally decline in health and die. The inorganics are especially needed in connection with the various secretions which have been referred to in a previous chapter. Inorganic, unlike organic substances, are eliminated from the body in the same form in which they enter. Water and salt, for in- stance, enter the body, perform their functions and are discharged as water and salt. Many of the former theories concerning nutrition have been abandoned as the result of recent investiga- tion. For instance, it has been quite clearly demon- strated that proteins do not directly form or repair old tissue, but that all food entering the body undergoes a chemical change, known as digestion; and that fol- lowing this the food products either are used for con- struction and repair of the various tissues of the body, or are burned to produce heat and energy. The latter is due to the presence of oxygen which is abstracted from the air in the lungs by the blood as it passes through these organs. The sum of the chemical 90 GOOD HEALTH changes which take place under the influence of living cells is known as metabolism. DIET Having considered in a general way the material re- quired for the nourishment of the body, we are better able to understand the value of the various articles of food, particularly under special conditions. It has been the custom of athletes while in training to eat sparingly of sugars and fats which increase the weight and are believed to add little to the muscular power of the body, but to depend chiefly upon proteins, such as eggs, meat and the like, from which to secure ad- ditional strength and proper material to replace worn out muscular tissue, for there is a pressing need of this during long continued and excessive muscular exercise. Proteins may be depended upon to do this; however it is now thought that sugars and fats are also factors in maintaining strength — for a while at least. In confirmation of this it is reported that dur- ing the present war, German soldiers have been sub- jected to prolonged and active exercise with a very limited supply of protein food. During convalescence from fevers or where emacia- tion exists, as in tuberculosis and other wasting con- ditions, fats and sugars are particularly indicated to make up for the general drain on the system, although proteins are also required. Aside from these special or temporary conditions, it will not be difficult to understand that a mixed diet which contains all forms of food is essential to continued health and strength. FOOD 91 During the past half century much has been done in the way of excluding fish, flesh and fowl from the diet, and also confining the character of the food within even narrower limits — to fruits and nuts, vari- ous grains, etc. Many societies have been formed for this purpose, the supporters being known as vegeta- rians, fruitarians, etc. Some of the advocates of these theories believe that in their practice they are dispens- ing with proteins. This is not a fact, for protein is not confined to meats and eggs, but is found in vegetables, often in large amount. Peas contain about twenty per cent of nitrogenized food ; some of the cereals are also rich in proteins. Yet vegetarians have done a vast amount of good by furnishing reliable evidence that we eat far too much meat and that this practice impairs digestion, tends to make those who are intemperate in this direction nervous and irritable, and later in life is unquestionably an important factor in causing organic diseases and other serious ailments. Conditions do exist where a generous supply of meat is not out of place, as in the case of those whose work involves con- tinued severe physical exercise. Unfortunately, how- ever, a full diet of meat is commonly partaken of by those of sedentary habits. As we have already learned, the function of food is not limited to the nourishment of the body. It must also generate heat and energy, as fuel does for the en- gine. In order that health may be maintained it is nec- essary that the body shall be kept at a temj>erature of about 98.6° F. With the many influences which af- fect the human system, it is one of the wonders of 92 GOOD HEALTH nature that this standard is mamtained ; yet this is the case, for while food furnishes the fuel which gener- ates the heat, means are provided to regulate it. No more practical or interesting illustration of the latter can be given than the protection which nature extends in this way in the case of firemen or stokers who feed the furnaces in the great ocean steamships and who are often subjected to a temperature of 125° F. or even higher. If the temperature of the body were raised to this point, death would quickly follow. Under these extreme conditions, the normal temperature of the body is maintained chiefly by profuse perspiration which neutralizes the external heat by evaporation. Nature can continue this unusual condition only for a limited time, and men who are thus employed must be frequently relieved by others, otherwise death or seri- ous illness may occur as the result of what is known as ''heat-stroke. " The temperature of the body is often raised by internal causes, such as infection, and medical and surgical treatment is required to assist nature to overcome it. The reduction of the body temperature below its normal register must also be carefully guarded against, for if this goes too far, equally serious results will fol- low. Aside from disease, this condition is usually the result of climatic conditions where the temperature is very low. If the exposure lasts for a short time only and the person is. in good health and well clad, he is not seriously affected ; but when long exposure is con- templated, means must be taken to prevent injury from this cause. In the Arctic regions where the tempera- FOOD 93 ture is continually very low, the person must not only be provided with very warm clothing, but must eat food which generates the greatest amount of heat. The diet of the Esquimaux is largely fat, usually in the form which would be nauseating to an inhabitant of the temperate or torrid zone and which would cause great discomfort and probably disease. We may feed an engine too much fuel, or use fuel of an improper kind. So may we take more food than we need for the nourishment of the body and the gen- eration of heat and energy, or we may partake of food which is deficient in nourishment, difficult to digest and disturbing to the machinery which disposes of it. These various conditions have led scientists to make a most careful and painstaking investigation concern- ing potential energy, or value of the various forms of food. This is now reckoned by calories. In plain words, a calory represents the amount of heat neces- sary to raise the temperature of one pound of water about 4° F. The experiments in this direction are made by burning the various articles of food in an apparatus in which the heat generated may be meas- ured. While this work goes far to establish a standard by which a normal diet may be approximately determined and rendered available for practical use and to furnish suggestion as to the character and amount of food best fitted for our nourishment, it must be borne in mind that this means of estimating food value deals with the subject largely from a theoretical standpoint. The heat developed by a certain form of food in experi- 94 GOOD HEALTH mental or laboratory work probably does not corre- spond to the amount of heat generated by it in the body, for here it is subjected to various changes over which we have little or no control. Besides, every per- son does not respond in the same way to the heat- and energy-producing capacity of food. Not only have scientists determined the relative amount of proteins, sugars and fats in the various foodstuffs, as well as the tissue building and caloric, or heat and energy, value of these articles, but esti- mates have been made as to the number of calories we need during the day to maintain the proper nourish- ment of the body. It is well known that persons of sedentary habits do not need as much food as those who perform man- ual work or are otherwise physically active. Under the former conditions, it is believed that food repre- senting about 2,500 calories is sufficient for the day's supply. An increase in this amount, however, is called for to sustain a person engaged in continued active exercise or at hard labor. This may require a daily supply of 4,000 to 5,000 calories. Naturally there is some difference in the estimates given by various in- vestigators, for the scientific deductions regarding this detail of the subject are largely theoretical. Valuable tables have been prepared enabling us to make practical use of the knowledge above referred to, and they furnish a valuable guide in the selection of a healthful and serviceable diet. It may be said concerning the relative amount of proteins, sugars and fats required for the proper main- FOOD - 95 tenance of the body, that about ten to twenty per cent should be proteins, something less of fat, and the re- mainder, or greatest portion, should be carbohydrates. The latter material constitutes the most important agent in the generation of heat and energy, aided by fats, although they have practically nothing to do with the repair or building of tissues ; whereas the proteins are alone concerned in this work, and contribute com- paratively little toward the production of heat and energy except in emergencies. The accompanying table is presented as a means of elucidating what has just been said regarding this part of the subject of nutrition, and is of practical impor- tance in showing that proteins are not confined to meats, eggs, etc., but are found to a large extent in vegetables and cereals and that proteins in the latter form may often be used as a substitute for meat. The great eco- nomic value of this is apparent. It is important in a general way that the public should be familiar with the scientific researches above referred to; but it would be unwise and impractical for a person to depend upon these data for the ar- rangement of a diet for daily use. It would be not only largely a matter of theory, but it would lead to all sorts of experiments and produce many so- called food cranks. It must be borne in mind that in- stinctively each race of people knows the food best adapted for its use. Besides, the appetite of a healthy person is a most excellent criterion of what form of food is best for him. The digestive apparatus, in its acceptance of the various articles of diet thrust upon ^a •"•M WWMMWfON^MM POM SS 00 Ov t^ O C^ o» ^ O O O w OM o» a.tso o o o 00 r^o o o o 00 00 N Os •-< i>oo t^ c^oo "^ t~ "^-O w o 00 t^ t^ OOOOOooOt^NMfOr^OO J3 ^ ^ OVCNOOOOO C>00 r^f*50\ MO\ ^tN N O ro ■^oo rO^^':^NOOlH^oO^>OrO MMMt-tMCS MMW MMM HHMM t^ M ■Tj- i-i M O N I'SOO O O 0\ fO •^ vO lOOO t^OO t~ MOO c^oo oooooo\'+ •M'+ioi/5»iio)"^Ninpoo(MOvo C4 ro rooo O)"*!^ C^ioro •^00\ t~ l>0 • t~~ • 0\ t>0 M Oi CM~ -cl- cN \0 fO O t^\0 ■^ -^vO M OOOO. OiOfO -t-* •lOC-^t^MOi'*'*'^ MMC^ M MMCS MM MMM. •NC^MMON'^'^ t^ ,i4 jH w § ?T3 c ?3 w O SSS. 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M S t-i (D Co TO CC ^j -tj +j +j . nJ c8 ts ce csXl-S c3 b o i2 - w S JS+^-S^ rt « s 0^ M te S^^^^^PHSStf2wWP-iPqUt/2PHiX!H, 74, 7S Water filters, 81, 82 Water supply, care of, 76, 77- 79, 82, 83 mosquitoes in, 213, 214 on shipboard, 84 pollution of, 72, 7A, 7S, 77j 79, 84, 123, 126 304 INDEX Water supply, public protec- tion of, 82, 83 sources of, 70, ^z, 75» 76, 17 Well water, "JT, 78, 79 Wells, construction of, 78, 79 poisonous gases in, 266 Wet weather, protection in, 170 Wheat, III White corpuscles, 20, 21, 195 White fibrous tissue, in ar- terial walls, 24 in ligaments, 14 in tendons, 17 Whitewash, 179 Wind-pipe, 32 Winter, clothing in, 168, 169 Winter, temperature varia- tions in, 168, 169 Wool, 166, 167, 168 Workshops, sanitation in, 187- 191 Wounds, classification of, 274-276 healing of, 276, 277 treatment of, 277-282 Wrist, 10 movement of, 13 Yellow elastic tissue, in blood-vessels, 24, 26 in ligaments, 14 Yellow fever, transmission of, 206 Yellow marrow, 3 (I) n ^x^ ^.> V