The foundation of health; a manual of personal hygiene for students

Preface

Too few of our intelligent people share the modern enlight¬ enment on personal hygiene and allied health problems. Health campaigns always suffer from the inability of the public to comprehend their purposes. Leading physicians and others who are not satisfied with this popular want of hygienic understanding look to the schools for its correction. School hygienists urge that the work of all periods of school life include some instruction concerning the maintenance of health. This text is designed for use in the early college years. It is based upon courses prepared for Junior College students at the University of Chicago, and for students enter¬ ing the study of medicine at the University of Texas.

I have taken a middle ground between the strictly applied and the physiological methods of teaching hygiene. My aim is not only to outline hygienic practices, but also to show how the functions of the body are affected thereby. If the student sees the connection between such practices and the health of his body, he is the less likely to be led astray by ridiculous fads, or to misapply scientific rules of health. On the other hand, too much stress on physiology diverts the theme of a short course from practical hygiene.

With the idea that scattered collateral reading is no less valuable than text-book study, I have suggested at the end of each chapter some appropriate references. Most of these are selected to afford. a broader, familiarity with the better

IV

PREFACE class of popular literature on personal health. A few inter¬ esting and non-technical chapters from scientific hooks are also listed for reading, to illustrate the immediate sources of our principles of hygiene.

I am indebted to Professors Edwin 0. Jordan and Dudley B. Reed of Chicago and Harry V. Atkinson of Galveston, to the Reverend James R. Sharp of Nashville, and to my wife, for suggestions and criticisms. Dr. Herman E. Dustin made the diagrams and sketches for me, using specimens in the collections of the University of Texas.

Galveston, Texas, 1924.

W. B. S.

Chapter I. The Problem Of Health And Disease

Hygiene.— Hygiene is the science of health; while in many particulars new, it is in principle very old. The name dates back to that of the goddess Hygieia and the Greek work for health (uyUta), and even when ancient Greece flourished the study itself was old. Health had been written about centuries before in Egyptian, and it had stirred man’s thoughts before he attempted to write at all. All primitive impulses are directed toward a healthful existence.

The knowledge of health at first was crude and merged into mysticism. Observations could not be made with refinement until modern science opened the way. Science enables us to care for our bodies much more sensibly than could our forbears. Recent advances have come so rapidly, however, that for many they have confused rather than clari¬ fied the issue. To be helpful, they must be so comprehended as to augment, and not confusedly supplant, the hygiene of common sense which has come down from antiquity.

Divisions of Hygiene.—Individual or personal hygiene covers what each individual should know in order to preserve his health. His responsibility is broader in an unhealthful than in a healthful locality. The avoidance of intestinal infection is an important personal care in Asiatic countries. To drink unsterilized water or to eat uncooked green foods there would be to invite an attack of dysentery or of typhoid fever. This is not the case in other regions with better sanitary 2 standards. Principles of personal hygiene are aimed at the preservation of one’s health amid existing surroundings.

In community life, where one disease threatens many persons, it is often economical to band together, employ a sanitary expert, and treat the problem as a whole. Purifi¬ cation of a polluted water supply is an instance. The per¬ son’s environment becomes safer by such collective action, which constitutes public hygiene. Instead of personally guarding his health, the individual surrenders his freedom of action and follows the direction of an accepted authority. The community decides for the welfare of all, and not each of its members for his own welfare. One problem after another is passing into the field of public hygiene: Contam¬ ination of water and food, contagion, use of habit forming drugs, and even the use of alcoholic drinks.

In the School.— Hygiene has not always attracted the attention of the general student, nor has physical health always been rated as a scholarly attainment. The ancient Greeks emphasized the need of a sound body for a sane mind, but the ascetics who kept learning alive through the dark ages lost this vision. To them the debasement of the body seemed to exalt the mind. Chinese civilization also has represented a wide divergence between mental and physical well-being; the stoop-shouldered learned classes would have abhorred the physique of a coolie laborer.

Modern scholars, of the West and of the East, idealize again the outstandingly healthy body and mind. Football and other school athletics are encouraged because they bring into the ideals of students the thought of health. Physical culture departments may concentrate on the few who least need development, but by doing so they lead all the students to admire a high physical standard.

Attainment of Health.— While the athlete is in most respects healthy and has always been accepted as a convenient model of health, the perfectly healthy individual need not be athletic at all. The ancients based their conception of health rather loosely on physical prowess and grace of posture, but with the advent of modern science the conception has crystallized more definitely into that of a proper functioning of all organs.

A model of supreme health might better be sculptured as a composite individual with all body functions perfected, about as the superman has been described.

An understanding by each individual of the needs of his own functions is the means to better health. Imitation of the physical habits of healthy men does not constitute a highway to health, because the functional needs of all indi¬ viduals are not uniform. While swimming improves the health of most boys, it occasionally kills one whom a defective heart exposes to cramps. The prize fighter’s enviable health can be credited to his pugilistic training, but men without his inherent neuromuscular capacity could be injured by such a course. The aim of personal hygiene is to have each person know how to overcome the impediments of his own bodily functions.

Environmental Hazards.—Raising the function of an organ to its greatest perfection only halfway assures the health of that organ. The athletic attainments from years of training can be wiped out in a day by a rheumatic infection; infection is one of the many adverse powers which stand ready to contest man’s development. The forces of nature are always ready to destroy those who are not protected from them. An unguarded child, without intelligent protection, could hardly survive them. They can burn or freeze, can smash one against the rocks at the foot of a cliff, or can kill the body tissues by an invasion of the germs of disease.

To these hazards of the primitive world, civilization has added its dangers. As man gets away from nature the chances of long life diminish; the industrial worker does not attain the average age of the farmer. The natural environ¬ ment of man’s origin favors his survival more than the artificial one which he has built up. Powers of destruction lurk in both, however, and to all of the environmental hazards must be added the hereditary taints and other personal faults which stand in the way of normal develop¬ ment. The forces of an enemy can thus be regarded as responsible for all the maladies suffered by man.

Protective Powers.—A condition of health implies the avoid¬ ance or surmounting of these obstacles. Man has a protective faculty with which to overcome them, and into this many factors enter. Ferments and other substances dis¬ solved in the body fluids tend to destroy those germs and germ products which gain admittance. Few would have gained admittance, for the body’s structural arrangement is such that the parts subject to attack are the parts least exposed. A tissue which is injured tends to grow and repair itself, and surviving organs do the work of parts which are lost. These shielding and compensating powers have been given the name vital resistance. The trained intelligence is also a protective force, when it supplements and guides our vital resistance.

Natural Resistance.—The resistive capacity is largely an inheritance. Structure and growing properties of tissue, certain instincts for self-preservation, and to a degree the substances which react against germs, all develop naturally. They are handed down from those who went before us. How the ancestral line built up this resistance is a question. Some would have it that as obstacles were encountered our progenitors acquired the power to overcome them and that they passed this power on to their descendants. Others argue that through vagaries of heredity some few chanced to be resistant, while untoward attacks killed off or checked the breeding of all others, so that only those with the greater resistance now have descendants. The first argument reads: Survival requirement-lability to overcome->transmissible trait, and the second just the reverse: Transmissible trait^ability to overcome^survival. Most of the evidence supports the latter view (selective survival), and does not suggest a likeli¬ hood that characteristics acquired due to environment can be passed on to offspring.

Acquired Resistance.—Resistant factors for the protection of the individual himself are certainly acquired, to the extent at least of a tremendous increase over what is inherited. Types of intelligence are acquired which protect better than the inherited instincts. In order to overcome certain infec¬ tions, protective ferment must be increased enormously over what was naturally present. An inherited quality which provides for much of this increase in resistive power is referred to as overrepair of injured tissue.

Most tissues repair themselves by the building of new tissue at the point injured. They build a great excess over the amount destroyed. If the tough layers of skin are worn from the hands, the repair is an excess of this tough skin, or a callous. Repair of broken bone is effected by a thick deposit of bony substance about the point of fracture; later the useless bony excess is gradually absorbed. Similarly, if the germ of scarlet fever attacks the substance protecting the tissues from

Fig 1.—Overrepair. Bone, several days after fracture.

it, that substance is replaced and reaches such excess that this variety of germ is overcome and cannot ever gain a second foothold.

When sufficiently resisted, therefore, a hostile attack leads to further increase in the resistance. The popular practice of carelessly overtaxing the functions of the body as a means to forcing up the resistance—spoken of as hardening, or as “growing more like a weed than a hothouse plant”—is not unsound in principle. It is better though, to know where the limit of endurance lies than to chance it, for permanent or fatal harm is done when the tissues suffer so greatly that they cannot repair themselves.

Toleration Limit.—The utmost limit of resistance, beyond which there is no control over an attack of disease, is spoken of as the limit of tolerance, or toleration limit to that disease. Such limits vary so widely among individuals that the same sort of abuse might further increase one’s resistance but break down another’s. It is this which precludes universal application of any set code of health rules. Natives can endure the tropical sun bareheaded, but only by wearing a protecting helmet can the visitor from temperate zones ward off sunstroke. The limit to most forms of natural resistance varies among individuals, and that to acquired resistance still more. It is usually possible, however, to make a work¬ able estimate of the amount of abuse which a body could stand.

The toleration limit to some antagonistic forces shows itself only by the signs of an approaching breakdown. It is often the prodromal symptoms, wdiich precede the regularly defined course of a disease, that first put people on their guard. By understanding these it is sometimes possible to check or abort the disease in its incipient stage, or if not, to avert some of its consequences. The earliest sign of a con¬ tagious disease, for instance, marks the time for isolation from other susceptible people.

Specificity of Resistance.—The powers within the body which protect from one particular disease are collectively termed a specific resistance to it. The resistance to scarlet fever above mentioned, with which the patient had been feebly endowed at the start and which multiplied so greatly as he recuperated, resists only this one disease. A specific resistance to many of the infectious diseases is abundantly acquired on recovery, and repetition of the attack becomes unlikely or impossible. Such resistance can be acquired only through an exposure of the tissue to action of the respective germ or of its products; in some fortunate instances this can be brought about otherwise than through an attack of the illness.

Other types of resistance are not limited to particular ailments and are termed general resistance. A healthy tissue is more resistant to many diseases than an injured one. Proper feeding, exercise, and temperance improve the func¬ tioning power of tissue and increase its general resistance; the reverse is the case with improper feeding, fatigue and dissipation. Many rules of hygiene are designed for the control of such general factors as these.

Production of Disease.—Health continues so long as the resistive powers of the body rise above the capacity of any destructive agents present. These agents are harmless if they do not exceed the body’s toleration limit to them. The campaign for health becomes a strife to subordinate the antagonistic powers; it is not always desirable to wipe them out, for the same powers may be useful. One does not go barefoot because shoes produce corns; instead the shoe is so fitted that its evils are within the control of the foot’s resist¬ ance. Only the agent which is sufficiently powerful to break the resistance, disturb some function, and do injury, produces disease.

Causative Agents.—Before detailing such functional dis¬ turbances, we might briefly survey and systematize the list of injurious agents. For present purposes, it will suffice to classify these into three groups, according to whether they are biological, physical, or personal. First, there are the living parasites, some of them animals, some plants and some bacteria. Second, there are the agents which injure the tissues mechanically, chemically, or by temperature extremes. Finally, there are upsets in the tissue economy from within.

Parasitism.—The first of the three groups requires the most explanation, for to many people germs are hazy and indefinite creatures. Parasites are organisms which attack living matter; from it they get their nourishment, and its life they thereby destroy. Their attack is not with any vicious intent, but because of an unfortunate defect which hinders the assim¬ ilation of other food than fresh tissue juices. All three of the kinds of parasites mentioned include many forms which can be fed from human tissues, though some of these show preference for the tissue of other animals.

Typically the unchecked course of a parasitic disease would run somewhat as follows: The germs find a pathway to some tissue on which they can live, and to grow there they kill and dissolve the tissue for food. The tissue is gradually thrown out of function; the patient dies if the function is one necessary to life, as is that of the heart valves. While grow¬ ing on the tissue, some germs would excrete into the blood stream a soluble toxin which is carried to and poisons other tissues. Action of toxin on nervous tissue leads often to paralysis or death.

a be

Fig. 2. —Microscopical parasites, a, Animal; b, bacterial; c, plant.

Vegetable Parasites Parasites of the first two varieties are tiny plants and animals, usually complicated in structure. Many varieties of either can live, feed, and multiply in one or another of the human tissues. The plants parasitic to man are all fungi. Many of them attack the skin, and many the lung or other deep tissue. Among them are included yeasts (blastomycetes), molds (hyphomycetes), and other fungi. Most authorities speak of bacteria also as fungi ( schizomy - cetes ) but for convenience we will regard them separately. When the bacteria are excluded, parasitism for human tissue is distributed much less widely through the plant than the animal kingdom.

Animal Parasites. —Four different phyla of the animal kingdom contain forms parasitic to man. Among the arthro¬ pods are mites and insects, the parasitic insects including lice, bugs, fleas, flies and mosquitoes. These attack most commonly the skin itself, or the deeper tissues through the skin. Other animal parasites are worms, of which the majority attack the intestine; these are of two phyla, consisting respectively of round and flat worms. The latter include leaf shaped {flukes) and tape shaped {tapeworms) forms. Many varieties of single-celled animals {protozoa) are para¬ sitic; some are found in the blood and others in the intestine.

A group of long spiral forms {spirochcetes), either protozoal or closely allied to the protozoa, has many parasitic members. In apparently close relationship with these are the filterable parasites {filterable virus; ultramicroscopic virus) . The latter cannot as a rule be seen, even with the highest powered mi¬ croscope. Some of them pass through a stage of existence in which they do reach microscopic dimensions; various shapes are assumed, among them the long spiral. Of all the para¬ sites, those of this variety alone can be carried with the fluids containing them through a fine pored filter. We recognize the diseases caused and we know that the patient’s blood has the invisible parasite in it, for this blood can trans¬ mit the disease to others, but we sometimes can only guess at the nature of the parasite. Most of the parasites of this group cause general systemic infections.

Bacteria.—Bacterial infections are the most frequently encountered of all parasitic diseases. The bacteria constitute an enormous group of living beings, leaning toward the plant but not falling clearly into either of the main biological kingdoms, as ordinarily defined. They are small and simply formed, measuring about 2 TTroo' of an inch across, and taking the form of a sphere {coccus), a rod {bacillus), or a spiral {spirillum)^ There are conditions under which they assume irregular shapes.

The simple forms break in two after perhaps fifteen or twenty minutes’ growth, each of the two parts then growing and dividing similarly; in this way they reproduce. In some cases there is only one division and in some cases many before the newly formed individuals separate from one another. The rods, which always divide crosswise, can thus form into pairs or chains. Some of the spheres divide off in different direc¬ tions, which can group them into clumps as well as into pairs or chains. The pair, chain, or clump is not the organism, however, but a group of distinct and functionally independent organisms.

Habitat and Culture— Bacteria are numerous, as a rule, wherever animals or plants could live. They are found chiefly near the surface of the land. Dust, and likewise whatever dust can reach, usually harbors them. Innumerable billions could be obtained from ordinary foods, water and milk, or from people’s mouths and intestines. Yet, due to minute size, their presence is appreciable only to technical observers. Not only are bacteria for the most part harmless, but in many instances they are of great service to man. Fertility of the soil, many industries, and even public sanitation plants, depend greatly on bacterial activity.

Fig. 3.—Bacterial cultures.

As food for their growth, most bacteria absorb water containing animal or vegetable matter in solution. Labora¬ tory workers feed them with a broth, made from partially digested animal tissue. A solution of commercial peptone and meat extract (culture bouillon) is sterilized in cotton plugged test-tubes, and to this broth the bacteria under observation are inserted with a sterilized wire. The pre¬ cautions are to keep out dust, contaminated with other bacteria. The bacteria in the broth absorb the food dissolved there and reproduce rapidly, until in a few hours they have produced a cloudiness or other visible evidence of growth. This is the bacterial culture. For convenience the broth may be soaked up into a mass of gelatin or of a seaweed jelly (agar-agar), the solids being melted into the broth by heat. When the mass cools, there is produced a fine sponge of gelatin or agar-agar filled with the broth, on the flat, solid surface of which the bacteria may be grown.

Pathogenicity .—Comparatively few kinds of bacteria have the capacity for parasitism. Instead of feeding on dead matter alone, these excrete a poison which kills the tissue and converts it into food for themselves. They are called pathogenic. Life on dead matter gradually reduces their power to kill tissue, while life on the living matter gradually increases this potency. Germs are accordingly most danger¬ ous when carried directly from an infected to a healthy per¬ son. Their power of destroying life is termed virulence, the highly virulent germs destroying very readily.

Some of the pathogenic bacteria, in addition to killing the tissue for food, excrete a soluble toxin. This is dissemi¬ nated through the blood stream and destroys tissues other than the one infected. One of the bacteria which is not parasitic at all causes disease and death by excreting a poison¬ ous toxin into foodstuffs.

Germicidal Influences .—Not only is it the adaptation to a new sort of food that diminishes the pathogenicity of a germ when removed from the tissues of a patient. Many of the forces in nature prove actively destructive to them. Some of the pathogenic bacteria can live only at body temperature, and are killed by variations of a few degrees from this. Others suffer from the action of light; light retards the growth of the germ of tuberculosis, for instance, and exposure to sunlight soon kills it. Oxygen prevents the growth of some germs, such as that of tetanus, and they cannot grow in the air; many other bacteria require a considerable supply of oxygen in order to live. A few of the bacteria escape these harmful influences by passing into a spore stage, having nothing to do with reproduction and serving only to keep them alive amid adverse surroundings. A hygienic signifi¬ cance of the bactericidal forces in nature will appear from later chapters.

Antiseptics.—Germs can often be controlled through ex¬ posure to agents which kill living matter, such as chemical antiseptics and a boiling temperature. Formalin, compound cresol solution, or carbolic acid are used to disinfect contaminated discharges from the body. These agents are about as destructive to tissue as to germs, but only the germs are exposed. It is also possible to prepare a strength of the antiseptic which will destroy germs, but not such tissues as are more resistant to it than the germs are.

Tincture of iodine is widely used to kill bacteria about the skin, though it is somewhat injurious to the tissue as well. Iodine may be used to kill the bacteria in a dirty wound, for the tissue repair remedies any destruction of tissue. Tissue already inflamed has too much bacterial growth to be entirely killed off and the tissue might gain less than it would lose in recuperative power. For application to the body’s external membranes, a 10 or 15 per cent solution of argyrol in water is effective. Boric acid solution is often used for copious washes or irrigations; a saturated or half-saturated solution has hardly any destructive effect on the tissue, and to a degree it does destroy germs.

When using any antiseptic on the body, the effect on the tissue as well as on the germ must be thought of. Anti¬ septics all destroy tissue, unless so weak as to be within the body’s toleration limit to them.

Accidents.—The antiseptics would appear with other poisonous chemicals in the second group of producers of dis¬ ease, as above classified. Little need be said of this group as a whole. The causation of wounds and frostbite is familiar to everyone. Mechanical and chemical injury results, as a rule, from accident. Accidents of childhood occur because the child’s mind is not yet an efficient protector, and because the discipline by its elders is loose. Accidents occur indus¬ trially because the workman’s care of himself is hampered by carelessness, fatigue, or alcoholism, and sometimes because of an unfitness of light, clothing, or working space. Safetyfirst propaganda, temperance, and proper working conditions are the preventives.

Upsets of Tissue Economy.—The final group of injurious factors, those classified above as upsets of the tissue economy from within, can best be taken up in connection with the respective organic functions. There are such faults as hereditary deformities which render the functions defective.

It is not to be inferred that all inherent shortcomings are in the nature of disease; the reference is only to those that bring about a definite malady. Healthy and properly func¬ tioning organs would be stronger in one person than in another.

An inherently normal function can be worn by excessive activity into a condition of disease; the organ becomes strained. Disturbance may also result from depriving a tissue of supplies it needs for its proper functioning; malnu¬ trition ensues.

Defective traits can best be defined when we discuss hered¬ ity, and strains, nutritional defects, etc., will be considered together with the functions with which they interfere. Such faults within ourselves can produce disease just as can antagonistic forces in the environment.

Prevention and Cure.— By forethought it is possible to assure the harmlessness of many powers of disease. Action based on such forethought is preventive medicine. It consists either in excluding from the body an antagonist, or in so raising the body’s resistance as to make the attack harmless. Pre¬ ventive medicine may be contrasted with curative medicine in that the former strives for the continuance of health and the latter for a reacquisition of lost health. Curative medi¬ cine follows the same fundamental principle as preventive. Disease results from partial destruction of the body’s vital and resistive forces, and the restoration of this broken resist¬ ance constitutes its treatment.

In a few diseases the germs are best destroyed by medicinal preparations, but more commonly the dependence is placed on the resistive substances in the patient himself. The patient goes to bed and waits for his tissues to overcome the antagonist. The usual error of the unskilled consists in doing too much, and particularly in upsetting the physiologic processes with medicines. Modern medicine makes compara¬ tively little use of drugs. The useful medicament is only that which produces in the tissue a specific and needed activity. Curative measures are for the most part entrusted to the physician and therefore assume less importance, in this study, than the preventive.

Health Perspective.— Problems both of prophylaxis and treatment entail the consideration of just how body functions are or might be affected. A true perspective of the problem of health is based on an understanding, first, of what the body’s functions are like when at their best; second, of what obstruc¬ tive powers might tend to interfere; third, of how far the body can be counted on normally to resist such powers; and finally, of what measures might so diminish the obstruc¬ tions or so increase the resistance that the functioning tissue can overcome them. Most of the succeeding chapters will follow this scheme of presentation, and consider in order the main functions of the body.

General, Hough and Sedgwick, Chapters XVI and XXX.

Nature and Disease, Brend, Chapter II.

The Problem of Health, J. F. Williams, Chapter II.

Resistance to Unfavorable Environment, Sedgwick, Chapter IV.

Parasitic Antagonists of Man, Chandler, Chapter I.

Bacteria and Their Relationship to Disease, Jordan, Chapters II and VII.

Hereditary Determinants of Health, Rapeer, Chapter III.

* See bibliography for titles and publishers of books.

Chapter II. Functions Of The Skin

The Body’s Envelope.— The skin and mucous membranes serve as an envelope to enclose and support deeper tissues, and to protect them from physical or parasitic injury. The skin and its appendages are chiefly responsible for an attrac¬ tive appearance. The elimination of any excessive body heat is also accomplished by this outermost tissue. Here, too, nerve endings take note of the environment, by various sensations such as touch, temperature sense, and pain.

Deep Skin.— The skin consists structurally of two layers, an outer or scarf skin ( epidermis ), and a true or deep skin {derma). While fused together into one coating, the two are distinct in that they consist of different kinds of cells. Cells are the tiny units of construction which make up the body. They measure in most cases less than toVo of an inch across, and differ in shape and material according to the sort of tissue which they compose. Most cells have a nucleus, well defined from the rest of the cell, and having a distinctive purpose which will be discussed later.

The cells of the deep skin are long, slender fibers or strands, which interlace and fuse into a tough fibrous tissue {connective tissue). On the strength of this fibrous layer the enclosed tissues depend for such support as the envelope affords. When its continuity is broken by a wound, fibers develop in excess to bridge over the defect. This overgrowth is the scar; the formation of a scar would not follow an injury to the outer skin alone, but only injury to deep skin or other fibrous tissue. Among the fibers which lie closest to the outer skin are innumerable fine bloodvessels and nerve endings. The ridges to be seen in the palms and soles are caused by particularly vascular and sensitive elevations of the deep skin.

Outer Skin.—The cells of the outer or scarf skin («epithelial cells) are irregular and variable in form and arrangement, somewhat comparable to the broken rock built into a mac¬ adam road except that the individual cells fit and are cemented together. Those next to the true skin have a tall, cylindrical form. Outward from these are many layers of cells, with the different dimensions more nearly equal. They are the reproductive or germinal cells of the outer skin, and they are continually in a process of growth and division. As new cells form they force the older ones outward toward the surface, and press them flatter and flatter. The very much flattened cells become tough and horny. Those at the surface are quite thin and scaly, and are gradually rubbed off.