Читать книгу Preventable Diseases - Woods Hutchinson - Страница 6

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The evil in things always bulks large in our imaginations. It is no mere coincidence that the earliest gods of a race are invariably demons. Our first conception of the great forces of nature is that they are our enemies. This misconception is not only natural, but even necessary on the sternest of physical bases. The old darky, Jim, in Huckleberry Finn, hit upon a profound and far-reaching truth when he replied in answer to Huck's question whether among all the signs and portents with which his mind was crammed—like black cats and seeing the moon over your left shoulder and "harnts"—some were not indications of good luck instead of all being of evil omen:—

"Mighty few—an' dey ain't no use to a body. What fur you want to know when good luck's a-comin'? Want to keep it off?"

It isn't the good, either in the forces of nature or in our fellows, that keeps us watchful, but the evil. Hence our proneness to declare in all ages that evil is stronger than good and that "all men are liars." One injury done us by storm, by sunstroke, by lightning-flash, will make a more lasting impression upon our memories than a thousand benefits conferred by these same forces. Besides, evil has to be sharply looked out for and guarded against. Well enough can be safely let alone.

The conviction is steadily growing, among both physicians and biologists, that this attitude has caused a serious, if not vital, misconception of the influence of that great conservative and preservative force of nature—heredity. We hear a great deal of hereditary disease, hereditary defect, hereditary insanity, but very little of hereditary powers of recovery, of inherited vigor, and the fact that ninety-nine and seven-tenths per cent of us are sane.

One instance of hereditary defect, of inherited degeneracy, fills us with horror and stirs us to move Heaven and earth to prevent another such. The inheritance of vigor, of healthfulness, and of sanity we placidly accept as a matter of course and bank upon it in our plans for the future, without so much as a thank you to the force that underlies it.

When once we clear away these inherited misconceptions and look the facts of the situation squarely in the face, we find that heredity is at least ten times as potent and as frequently concerned in the transmission and securing of health and vigor as of disease and weakness; that its influence on the perpetuation of bodily and mental defects has been enormously exaggerated and that there are exceedingly few hereditary diseases.

It is not necessary for our present purpose to enter into a discussion of the innumerable theories of that inevitable tendency of like to beget like, of child to resemble parent, which we call heredity. One reference, however, may be permitted to the controversy that has divided the scientific world: whether acquired characters, changes occurring during the lifetime of the individual, can be inherited. Disease is nine times out of ten an acquired character; hence, instead of the probabilities being that it would be inherited, the balance of evidence to date points in exactly the opposite direction. The burden of proof as to the inheritance of disease is absolutely upon those who believe in its possibility.

Another fundamental fact which renders the inheritance of disease upon a priori grounds improbable and upon practical grounds obviously difficult, is that characters or peculiarities, in order to be inherited certainly for more than a few generations, must be beneficial and helpful in the struggle. A moment's reflection will show this to be mathematically necessary, in that any family or race which tended to inherit defects and injurious characters would rapidly go down in the struggle for survival and become extinct. An inherited disease of any seriousness could not run for more than two or three generations in any family, simply for the reason that by the end of that time there would be no family left for it to run in. A slight defect or small peculiarity of undesirable character might run for a somewhat longer period, but even this would tend toward disappearance and elimination by the stern, selective influence of environment.

Naturally, this great conservative tendency of nature has, like all other influences, "the defects of its virtues," as the French say. It has no gifts of prophecy, and in the process of handing down to successive generations those mechanisms and powers which have been found useful in the long, stern struggle of the past, it will also hand down some which, by reason of changes in the environment, are not only no longer useful, but even injurious. As the new light of biology has been turned on the human body and its diseases, it has revealed so many of these "left-overs," or remnants in the body-machine—some of most dramatic interest—that they at first sight have done much to justify the popular belief in the malignant tendencies of heredity.

Yet, broadly considered, the overwhelming majority of them should really be regarded as honorable scars, memorials of ancient victories, monuments to difficulties overcome, significant and encouraging indications of what our body-machine is still capable of accomplishing in the way of further adjustment to conditions in the future. The really surprising thing is not their number, but the infrequency with which they give rise to serious trouble.

The human automobile is not only astonishingly well built, with all the improvements that hundreds of thousands of generations of experience have been able to suggest, but it is self-repairing, self-cleaning, and self-improving. It never lets itself get out of date. If only given an adequate supply of fuel and water and not driven too hard, it will stand an astonishing amount of knocking about in all kinds of weather, repairing itself and recharging its batteries every night, supplying its own oil, its own paint and polish, and even regulating its own changes of gear, according to the nature of the work it has to do. Simply as an endurance racer it is the toughest and longest-winded thing on earth and can run down and tire out every paw, pad, or hoof that strikes the ground—wolf, deer, horse, antelope, wild goat. This is only a sample of its toughness and resisting power all along the line.

These wide powers of self-support and adjustment overbalance a hundred times any little remnant defects in its machinery or gearing. Easily ninety-nine per cent of all our troubles through life are due to inevitable wear and tear, scarcity of food-fuel, of water, of rest, and external accidents—injuries and infectious diseases. Still, it occasionally happens that these little defects may furnish the point of least resistance at which external stresses and strains will cause the machine to break down. They are often the things which prevent us from living and "going to pieces all at once, all at once and nothing fust, just as bubbles do when they bust," like the immortal One-Hoss Shay. It is just as well that they should, for, of all deaths to die, the loneliest and the most to be dreaded is that by extreme old age.

These vestigia or remnants—instances of apparently hidebound conservatism on nature's part—are very much in the public eye at present, partly on account of their novelty and of their exceptional and extraordinary character. Easily first among these trouble-breeding remnants is that famous, or rather notorious, scrap of intestine, the appendix vermiformis, an obvious survival from that peaceful, ancestral period when we were more largely herbivorous in our diet and required a longer and more complicated food-tube, with larger side pouches in the course of it, to dissolve and absorb our food. Its present utility is just about that of a grain of sand in the eye. Yet, considering that it is present in every human being born into the world, the really astonishing thing is not the frequency with which it causes trouble, but the surprisingly small amount of actual damage that arises from it. Never yet in even the most appendicitis-ridden community has it been found responsible for more than one half of one per cent of the deaths.

Then there is that curious and by no means uncommon tendency for a loop of the intestine to escape from the abdominal cavity, which we call hernia. This is one of a fair-sized group of dangers clearly due to the assumption of the erect position and our incomplete adjustment thereto. In the quadrupedal position this necessary weak spot—a partial opening through the abdominal wall—was developed in that region which was highest from the point of view of gravity and least exposed to strain. In the bipedal position it becomes lowest and most exposed; hence the much greater frequency of hernia in the human species as compared with any of the animals.

Another fragment, of the impertinence of whose presence many of us have had painful proof, is the third or last molar, so absurdly misnamed the wisdom tooth. If there be any wisdom involved in its appearance it is of the sort characterized by William Allen White's delicious definition: "That type of ponderous folly of the middle-aged which we term 'mature judgment.'" The last is sometimes worst as well as best, and this belated remnant is not only the last to appear, but the first to disappear. In a considerable percentage of cases it is situated so far back in the jaw that there is no room for it to erupt properly, and it produces inflammatory disturbances and painful pressure upon the nerves of the face and the jaw.

Even when it does appear it is often imperfectly developed, has fewer cusps and fewer roots than the other molars, is imperfectly covered with enamel and badly calcified. In no small percentage of cases it does not meet its fellow of the jaw below and hence is almost useless for purposes of mastication. But it comes in every child born into the world, simply because at an earlier day, when our jaws were longer—to give our canine teeth the swing they needed as our chief weapons of defense—there was plenty of room for it in the jaw and it was of some service to the organism. If the Indiana State Legislature would only pass a law prohibiting the eruption of wisdom teeth in future, and enforce it, it would save a large amount of suffering, inconvenience, and discomfort, with little appreciable lack of efficiency!

In this list of admitted charges against heredity must also come the gall-bladder, that curious little pouch budded out from the bile ducts, which has so little known utility as compared with its possibility as a starting-point for inflammations, gall-stones, and cancer.

Then there is that disfiguring facial defect, hare-lip, due to a failure of the three parts of which our upper jaw is built to unite properly—this triple construction of the jaw being an echo of ancestral fishlike and reptilian times when our jaws were built in five pieces to permit of wide distention in the act of swallowing our prey alive. All over the surface of the body are to be found innumerable little sebaceous glands originally intended to lubricate hairs, which have now atrophied and disappeared. These useless scraps, under various forms of irritation, both external and internal, become inflamed and give rise to pimples, acne, or "a bad complexion."

And so the list might be drawn out to most impressive length. But this length would be no indication of its real importance, inasmuch as the vast majority of entries upon it would come under the head of pathological curiosities, or conditions which were chiefly interesting on account of their rareness and unusual character. With the exception of the appendix, the gall-bladder, and hernia, these vestigial conditions may be practically disregarded as factors in the death-rate.

In the main, when the fullest possible study and recognition have been made of all the traces of experimentation and even of ancient failure that are to be found in this Twentieth Century body-machine of ours, the resulting impression is one of enormously increased respect for and confidence in the machine and its capabilities. While they are of great interest as indicating what the past history and experiences of the engine have been, and of highest value as enabling us to interpret and even anticipate certain weak spots in its construction and joints in its armor, their most striking influence is in the direction of emphasizing the enormous elasticity and resourcefulness of the creature.

Not only has it met and survived all these difficulties, but it is continuing the selfsame processes to-day. So far as we are able to judge, it is as young and as adaptable as it ever was, and just as ready to "with a frolic welcome greet the thunder and the sunshine" as it ever was in the dawn of history.

These ancestral and experimental flaws, even when unrecognized and unguarded against, have probably not at any time been responsible for more than one or two per cent of the body's breakdowns; while, on the other hand, every process with which it fights disease, every trick of strategy which it uses against invading organisms, every step in the process of repair after wounds or injury, is a trick which it has learned in its million-year battle with its surroundings.

Take such a simple thing as the mere apparently blind habit possessed by the blood of coagulating as soon as it comes in contact with the edges of a cut or torn blood-vessel, and think what an enormous safeguard this has been and is against the possibility of death by hemorrhage. So well is it developed and so rapidly does it act that it is practically impossible to bleed some animals to death by cutting across any vessel smaller than one of the great aortic trunks. The rapidity and toughness of the clotting, combined with the other ancestral tricks of lowering the blood pressure and weakening down the heart, are so immensely effective that a slash across the great artery of the thigh in the groin of a dog will be closed completely before he can bleed to death. So delicate and so purposeful is this adjustment that the blood will continue as fluid as milk for ten, twenty, forty, eighty years—as long as it remains in contact with healthy blood-vessels. But the instant it is brought in contact with a broken or wounded piece of a vessel-wall, that instant it will begin to clot. So inevitable is this result that it gives rise to some of the sudden forms of death by bloodclot in the brain or lung (apoplexy, "stroke"), the clot having formed upon the roughened inner surface of the heart or of one of the blood-vessels and then floated into the brain or lung.

Then take that matchless and ingenious process of the healing of wounds, whose wondrousness increases with every step that we take into the deeper details of its study. First, the quick outpouring and clotting of the blood after enough has escaped to wash most poisonous or offending substances out of the wound. This living, surgical cement, elastic, self-moulding, soothing, not only plugs the cut or torn mouths of the blood-vessels, but fills the gap of the wound level with the surface. Here, by contact with the air and in combination with the hairs of the animal it forms a tough, firm, protective coating or scab, completely shutting out cold, heat, irritants, or infectious germs.

Into the wedge-shaped, elastic clot which now fills the wound from bottom to top like jelly in a mould, the leucocytes or white blood-cells promptly migrate and convert it into a mesh of living cells. They are merely the cavalry and skirmishers of the repair brigade and are quickly followed by the heavy infantry of the line in the shape of cells born of the injured tissues on either side of the wound. These join hands across the gap, the engineer corps and the commissariat department move up promptly to their support in the form of little vein-construction switches, which bud out from the wounded blood-vessels. The clot is transformed into what we term granulation tissue and begins to organize. A few days later this granulation tissue begins to contract and pull the lips of the wound together. If the gap has not been too wide the wound will be completely closed, its lips and deeper parts drawn together in nearly perfect line, separated only by a thin scar on the surface with a vertical keel of scar tissue descending from it. If the lips cannot be drawn together and there be no surgical skill at hand to assist them with stitches or bandages, then the gap will be filled up by the fibrous transformation of this granulation tissue and a thick, heavy scar result. Meanwhile, the skin-cells of the surface have not been idle, but are budding out on either side of the healing wound, pushing a little line of colonists forward across the raw surface. In longer or shorter time, according to the width of the gap, these two lines meet, and the site of our wound or the scar that it has left is perfectly coated over with a layer of healthy skin. This drama has occurred so many score of times in every one of us that custom has blinded our eyes to its ingenious perfection, but it took a million years to bring it to its present finish.