Popular Science Monthly/Volume 7/June 1875/The Conservative Design of Organic Disease
|THE CONSERVATIVE DESIGN OF ORGANIC DISEASE.|
By Prof. A. F. A. KING, M. D.
IF we should say that diseases prolong life, that without them man would be more liable than he is to sudden death, the announcement would be received by most medical thinkers, and by all those who have never studied pathology at all, as a transcendental idea, quite insusceptible of logical proof. But it is otherwise: that certain processes of disease are really conservative, and contribute to the longevity of the individual, is an absolute fact, as we shall now endeavor to demonstrate.
Let it be noted that almost from time immemorial physicians have recognized in the body a certain power of resisting injuries, and of returning spontaneously to health, when disordered; and this they have called the power of Nature—the vis medlcatrix naturæ. The growth of this idea culminated, during the sixteenth century, in the establishment of the so-called "Stahlian system of medicine." And, while the doctrines of Stahl were sustained and elaborated by many of the leading physicians of his day, we now know they were erroneous, for he maintained that there resided in the organism a "rational soul" which, he affirmed, not only formed the body, but excited and directed all of its motions; it was alleged to perceive intelligently the tendency of all external impressions acting upon the body, and to excite such motions as would favor the beneficial and obviate the injurious influence of such impressions. Hence, generally speaking, diseases were considered to be salutary efforts of the "presiding soul," and were to be assisted, and not interrupted, by the interference of art; it was, however, admitted that the "rational soul," owing to surprise, fear, or despair, occasioned by too sudden or vehement impressions made upon it, would sometimes excite adverse motions which it was right to moderate.
Prevailing only for a season, the system of Stahl was finally abandoned as a visionary hypothesis; it was deprecated, as leading physicians to neglect the use of remedies; for its followers, trusting chiefly to the attention and wisdom of Nature, adopted the inactive mode of curing by expectation—la médecine expectante, as the French term it. The use of opium, cinchona, mercury, and other potent medicines, was zealously opposed by the Stahlian physicians, and they were extremely reserved also in the use of bleeding, emetics, and other evacuant remedies.
Before we dismiss this part of the subject, it may be worth while to note, as illustrating the not uncommon cyclical revolution of opinion on scientific questions that are yet unsettled, that the medical practitioners of to-day—at least the best or most successful of them—have adopted the identical mode of practice for promoting which the doctrine of Stahl was allowed to fall into disrepute. Nowadays, like the Stahlians of old, we have laid aside bleeding and emetics, mercury and evacuants, and, content with feeding the patient and contributing to his comfort, we leave the disease to take care of itself—e trust again to the vis medicatrix naturæ. The physician of to-day who should boast of curing a disease (unless, indeed, it were an ague, with quinine), would be considered, by his more highly-informed fellow-practitioners, as profoundly ignorant of the recent advances made in the science of pathology.
Another erroneous hypothesis, not differing very widely from the idea of Stahl, and which may be named and dismissed before we proceed, is that which supposes the existence, in the nervous system, of some tangible, central point of nerve-matter, from which, as from a seat of government, mandates are issued to control the motions and changes that take place in every quarter of the organism; and which leads us to infer that processes of disease, since, as it would seem, they are allowed to take place by this governing "central point," would be rather protective than-suicidal to the individual. This view—never very widely acknowledged—received its final death-blow by the publication of Virchow's "Cellular Pathology," in which it was shown that the entire organism, in all its parts, is really composed of an indefinite number of individual centres, in fact cells, each of which has a life of its own, performs its own functions, and dies its own death: it is the invisible motions of these millions of microscopic entities, which, in the aggregate, constitute the visible changes and actions which we say characterize life. The anatomist has never discovered any "central point," nor the microscopist any "single cell," which governs the motions of the rest. Every supposed "central point" has been found, on microscopic examination, to split up into innumerable millions of centres, or individual cells. Moreover, in plants, in which the processes of life appear to be directed quite as intelligently as they do in animals, no trace of a nervous system has yet been demonstrated.
To many of my readers it would perhaps be a much more acceptable explanation of the (what seem to be) intelligently-directed processes going on in living bodies, than either of those already mentioned, to say that they must be ascribed to the rational will of a Creator urging an unconscious organism, by the laws he has ordained, to perform certain acts necessary to its preservation.
But, as the absolute scientists and those who religiously believe in a Creator are just now crossing swords, I will not press this third explanation, but rather choose to sustain the position I have assumed on the broader middle ground of natural philosophy.
To return, therefore, to the main proposition, namely, that organic diseases are naturally designed for, and do in fact accomplish, the prolongation of life, it will be observed that I have purposely omitted from consideration those other and more simple kinds of derangement which we call functional diseases. The conservative use of many of these latter has been universally recognized. The vomiting that occurs when poisons or indigestible matters have been introduced into the stomach, does good, by removing the offending substances. In like manner, the functional derangement of cough secures the expulsion of irritating gases or powders that have been inhaled, and of the accumulations of mucus that occur in every bronchial catarrh, and which would otherwise clog the tubes and induce suffocation. The watery diarrhœas that arise from indigestible articles having passed into the intestine, cure themselves by washing away the irritating materials, and the intelligent physician, instead of curbing the derangement, assists it with a laxative, and so helps Nature with the cure.
When, however, we come to speak of the more permanent structural changes, which neither Nature nor art can remove, and which have seemed to produce premature death, scarcely any one will acknowledge that the processes which develop them are at all conservative. Yet they are. And the error of supposing they are not has arisen chiefly from a total misunderstanding as to the nature of disease. A very prevalent idea, if not indeed a universal one, seems to be, that disease is a separately-existing entity—a thing independent of the body and inimical to it. We constantly hear, for example, of an individual being "attacked" with pneumonia; of an army "assailed" with small-pox; of a city "assaulted" with cholera, and of its inhabitants being decimated by the "stealthy ravages" of consumption. Now, so considered, there is no such thing as disease. Who has ever seen it isolated from the body?—And when, in accordance with this view, we ask the question, "What is disease?" there is but one answer, namely: Disease is the tertiary product of two factors: 1. Of impressions or stimuli acting upon the body from without; and, 2. Of the reactions performed by the organism in response to the impression of such stimuli. The tertium quid following the action without, and the reaction within, is the thing "disease." Exactly in the same manner a stone thrown against a pane of glass makes a hole in it; yet, when we try to consider the hole as a separately-existing entity, we find it does not so exist. If it did, we might take away the pane of glass, and leave the hole by itself, but this is impossible. The aperture in the glass is a tertium quid resulting from two factors, viz., 1. The action of the stone from without; and, 2. The reaction of the glass when struck by the projected missile. Furthermore, it is evident that the quality of the resulting tertiary product can be made to vary indefinitely, either by varying the character of the action (i, e., by modifying the shape, size, direction, velocity, etc., of the stone), or by altering the reactive properties of the glass (i. e., by modifying its thickness, elasticity, inclination, etc.). Equally so the quality of disease will vary in different individuals in accordance with the variation in the quality of their reactive powers, as well as in conformity with the character of the actions by which the reactions are elicited.
Now, since the external stimuli which act upon the body in the manner we have described only produce their effect in living organisms (for in dead bodies and inorganic matter they do not elicit similar reactions), it is evident that the tertiary products which we call organic disease are purely the result of vital processes, and for this reason alone must be conservative, as are all the phenomena of life. Once dispute this and we should have to adopt the other alternative, that the organism would be better off if the reactive powers with which we find it to be endowed were annulled; and this conclusion would compel us to acknowledge the possibility of our thinking out an improvement upon Nature—a monstrous assumption, which no student of science will for a moment entertain.
In a condition of health the various processes going on in the body, which we call vital phenomena, are nothing more than a series of internal reactions provoked and maintained in obedience to the impression of surrounding conditions that act upon the organism from without. The reactive powers possessed by the healthy organism are perfectly natural to it, and, so long as the external stimuli impressing the body from without are also perfectly natural, the resulting tertium quid will simply consist of a naturally-constructed, a physiologically-developed organism. And if we now ask ourselves, "What is the use or design of organs and structures that have thus followed a perfectly normal course?" we are soon able to discover that there exists between the developed organs and the external stimuli which provoked their development a mutual relation of such a kind that one is perfectly adapted to the other; in a perfectly natural state, physiological organisms are nicely adjusted to the external conditions surrounding them, in which it is natural for them to live, and which require of the organs developed just such functions as their formation and power adapt them to perform. Adaptation of the organism to its environment is, therefore, the grand purpose of the peculiarities of structure observed in different animals and plants. It is almost needless to present illustrations; they occur without number, and are quite apparent to the most superficial observer. The digestive organs are differently constructed in the herbivorous and carnivorous animals, and are thereby adapted to the different kinds of food on which the animals subsist. The gills of fish and the lungs of mammalian quadrupeds are structurally and functionally unlike; the differences adapting the breathing-apparatus of each animal to the particular kind of respiratory medium in which it is to live. And so of all other organs.
Now, if, instead of permitting the organism to remain living in its natural state, we change the surrounding natural conditions to others that are unnatural, the action of these latter will excite in the organism corresponding unnatural reactions: at first an unnatural modification of function will ensue; and in time, if the modified functions are in this manner continued, we observe a corresponding modification of structure to follow. But the modifications of structure, thus induced, are nothing else than organize diseases; they are departures from the physiological standard of health. And if we ask, "What is the conservative use and designed purpose of these unnatural deviations?" the answer is, that the modifications of structure adapt the affected organs to modified functions that they have been called upon to perform and mould the organism to new conditions that have been brought to act upon it; just as variation in the physiological construction of different animals adapts them to the various differences of surrounding media in which they are designed to live. Pathology, therefore, is really nothing else than modified physiology. Physiological development is the evolution of organs and the growth of organisms under the impression of natural external conditions; pathological development is the evolution of organs and the growth of organisms under the impression of unnatural external conditions. Adaptation of structure to function—of organisms to surrounding media—is the designed conservative purpose of both kinds of growth.
Furthermore, as no two human organisms are ever, in any particular, precisely similar, and as between organisms that have followed a strictly physiological development, and those whose development has been decidedly pathological, there are still others of intermediate character, whose deviation from physiological and approach to pathological development have been less decided, or extremely slight, it is evident there exists between the two kinds of growths no well-defined line of demarkation; physiology and pathology run gradually into each other. It is not possible to say where one ends and the other begins. That this must be the true state of the case is unmistakable when we consider that the change of external conditions from natural to unnatural may be in any—the slightest or the most extreme—degree. Thus we frequently observe modifications of structure induced by exceptional conditions that have been brought to act upon the body, of so trivial a character that they can hardly be called diseases, while at the same time they are in some measure anomalous deviations from the typical standard of the species; but in these, as in the higher grades of structural modification, it will be seen that the conservative purpose of adaptation is carried out. For example, the muscles in the right arm of the blacksmith, those of the leg-calf in the limbs of the dancer, and the crural adductors of the jockey, undergo a process of increased growth (a physiological hypertrophy) by which they become adapted to the increase of function imposed on them. So the thickened epidermis of a laborer's palm adapts the hand—by protecting the softer tissues underneath from being bruised—to the rough handling of manual instruments; an adaptation altogether wanting in one unaccustomed to labor, as evidenced by the inflamed and blistered condition of his hands when first beginning to practise such exercises. By the same kind of thickening and induration the finger-ends of the violinist become adapted to sustain without inconvenience prolonged pressure upon the strings of his instrument. When the main artery of a limb has been obstructed, or tied by the surgeon's ligature, we find the nutrition of the tissues beyond is supported by the blood finding its way through the smaller anastomosing arteries, and in time we observe these smaller arterial branches to become considerably enlarged, thus adapting themselves to the increased amount of blood they have been called upon to transmit. In cases where obstruction to the arterial circulation is more general, so that it requires an increased heart-force to pump the blood through its channels, we observe the heart itself to become larger, and thus its increase of structure (like the blacksmith's arm) is adapted to the required increase of function. The head of the thigh-bone, when irreducibly dislocated, becomes surrounded in its new position with fibro-ligamentous and muscular structures, which so far resemble an articulation as to permit the patient to walk about. Similarly in ununited fractures, we find the ends of the broken bone, when the muscles attached to them cause the fragments to move one against the other, become covered with cartilage and encapsulated with fibrous and ligamentous tissues, so as to form the "false joint" of surgeons. Mucous membranes, when continuously exposed to the air, adapt themselves to their new situation by becoming covered with a layer of epidermis closely resembling skin. Of this we have a good illustration in long-standing cases of procidentia uteri, where the vaginal mucous membrane is often continuously exposed.
The vegetable world also furnishes numerous illustrations showing how plants adapt themselves, by modification of structure, to new conditions in which they have been placed. The geranium in our window, instead of growing in its naturally vertical direction, disposes its twigs and branches obliquely on one side, thereby adapting them, their leaves, blossoms, etc., the better to receive the rays of light that come in slanting through the window. Plants kept more or less in the dark, have a deficiency of color; they become bleached and white, but this lessened opacity of their skin, this increased transparency of tissue, enables them to make the most of what little sunshine is allotted them.
The sprouts of an onion or potato, when kept in a dark chamber, grow to an unusual length, and, although this elongation can accomplish no good when the bulb is packed in a barrel, or housed in a cellar, still it is evident that the plant is obeying the same laws of adaptive growth by which, when buried deeply in the earth, its sprouts increase in length until they reach the sunny surface of the soil.
Now, while these instances (and many others might be added) certainly furnish unequivocal evidence of a disposition on the part of organs and organisms to adapt themselves to new conditions in which they have been placed, and to altered functions they have been required to execute, yet it must be admitted they exhibit little or no proof that those other organic alterations, which we regard as fatal diseases, are imbued with the same conservative design. In fact, to meet the issue at once—to strangle the serpent before we take out his fangs—it is necessary to dispose of the objection that organic diseases, structural formations resulting from pathological development, produce physical pain, and lead to death; for that they do so is the common belief.
To meet this objection it is simply required to follow out the analogy, already alleged, between structures resulting from physiological development and those produced by development that is pathological. That the causes and objects of the two kinds of growths are the same, has been previously intimated. We proceed by calling attention to (what may surprise those who have not given the subject proper consideration) the great fatality attending physiological evolution:
Very young animals, and indeed young plants, are peculiarly liable to die before reaching maturity. This is especially the case in animals, at least during the first few days of life, but the liability continues, though in a gradually-decreasing ratio, until physiological development is complete. Breeders of stock know very well the difficulty of rearing the young; and even in wild animals that live in a perfectly natural state, untrammeled by domestication, a good proportion of new-born individuals perish in early life. Gardeners and agriculturists drop more seeds in a place (of corn "in a hill," for instance) than they intend shall remain as plants, knowing that in the earlier stages of growth many of the "seedlings" will die; and, if more shall remain than is advisable, they are afterward "thinned" by hand. Surely every mother of a family knows the difficulty of rearing children, and our "bills of mortality" sufficiently attest the immense fatality attending physiological development in the human family.
Now, while in each of the instances I have cited the causes and mode of death are similar to or at least analogous with each other, it is only in the case of our own species that, generally speaking, we say death has been caused by disease. In the young chick, the wild animal, and the seedling plant, we are content to say they die because they are young, or "tender." The truth is, that death has been due, in each case, to an arrest of, or interference with, the quite normal process of physiological development, and to put this conception to a further test we may begin still a little earlier in life by studying embryonic development. In the case of oviparous animals, for example, we know many of the eggs never come to perfection; the young embryos they contain die during incubation. And while the pathologist, if he were to delve with his microscope into the secret physiology and pathology of the growing embryo, might find different membranes and organs fatally affected (congested or inflamed) according to the different stages of development at which the mortal disturbance took place, it would seem very odd, in case it should happen to be the rudimentary lungs of the growing embryo that were found specially congested, if he should say the egg had been "attacked" with pneumonia (inflammation of the lungs); or, if he should find the heart or intestines congested, how queer it would sound to say the egg had died from an attack of carditis (inflammation of the heart), or enteritis (inflammation of the intestines)! yet these so-called diseases are just as much causes of death in the egg as in the child after it is born.
The relevancy of the facts mentioned to the question at issue—the bearing of the argument—is this: organisms undergoing physiological evolution, and those in which pathological evolution is going on, are alike liable to be fatally affected by certain disturbing causes that interfere with the typical progress of development in each; hence the great mortality incident to childhood and early life is strictly analogous with the mortality attending organic diseases in the adult.
This analogy may now be further sustained by considering what these disturbing causes really are; and here I may premise they will be found to be the same both in physiological and pathological development.
Most prominent among the conditions necessary to secure the normal progress of physiological development is warmth; and nothing moreinterferes with it, or more quickly arrests it, than exposure to cold. In fact, an elevated temperature is the initial power—the first mover of the developmental process in all organisms, vegetable as well as animal. It is solar heat that forces the seed to germinate, the plant to bud, and the flower to bloom. Without warmth the fecundated egg of the oviparous animal would ever remain an inert mass; hence the snake deposits her germs in a dunghill of rotting vegetable matter where they may be warmed by the heat of fermentation. The ostrich intrusts her egg almost entirely to the sun-baked sand of the African desert; and birds in general incubate for days or weeks to supply the necessary heat for securing the development of their eggs. Fish inhabiting waters that are deep and cold, seek shallower and warmer streams in which to deposit their spawn. The difference between the warm and the cold seasons of the year, as regards the prevalence of reproduction, in both animals and plants, is familiar to every one.
But, besides heat being the primum mobile of normal evolution, it is equally necessary to maintain it when already begun. Exposure to cold is fatal. The shivering of young animals—their great liability to become chilled on exposure-to a depressed temperature—has been observed by every one; and in the breeding of domestic animals, as in the cultivation of plants, there is probably no more potent source of mortality than insufficient warmth; and, further, this mortality is found to be more prevalent during unusually cold seasons. Now, the young of our own species form no exception to this rule; they, too, are liable to suffer a fatal arrest of physiological development on being exposed to cold. Thus, in a statistical inquiry as to the average number of deaths at different seasons, and at different ages, from a table prepared by M. Quetelet, of Brussels, it appears that, during the first month of infant life, the external temperature has a very marked influence; for the average mortality during each of the three summer months being 80, that of January is nearly 140, and the average of February and March 125. This is confirmed by the result obtained by MM. Villermé and Milne-Edwards in their researches on the mortality of the children conveyed to the foundling hospitals in the different towns in France; for they not only ascertained that the mortality is much the greatest during the first three months in the year, but also that it varies in different parts of the kingdom according to the relative severity of the winter.
Additional proof of the disastrous influence of cold in early life, and, by-the-way, an explanation of the apparent natural defect in growing organisms implied by the existence of a liability to be fatally injured by it, may be found in the fact that Nature has amply provided for maintaining all very young animals at an elevated temperature, and protecting them from external cold. Note, first, how animals usually breed during the seasons of spring and summer; and observe, further, how the bird feathers her nest for the reception of her young, and shelters them under her wings, at the same time imparting heat by the contact of her own warm body. Rabbits and other animals tear off the fur from their own skins in order to provide a warm bed for the young while the parent is away in search of food. Frequently, too, animals are born in broods, or litters, especially those that are nearly nude at birth, and incapable of generating heat by exercise, and thus warmth is generated, or at least maintained, by the crowding together of a number of individuals in a small space.
Whether the liability, on the part of young animals, to be injuriously influenced by cold, is owing to their vital forces being so taken up with the process of growth as to leave a smaller surplus of vitality to resist the chemical agency of a diminished temperature, or whether it is that the lack of muscular exercise in them prevents the development of heat, we may not be able to determine; but this question is immaterial so far as the fact itself is concerned, that cold acts injuriously. It seems not improbable that the liability to be unusually affected by cold may depend upon rapidity of organic change. Thus those organs are most readily affected whose evolution is in most rapid progress; hence the digestive organs of the child and its pulmonary tissues are more apt to suffer from a depressed temperature than its reproductive organs; the former are undergoing rapid development, the latter are in a state of almost complete quiescence. Similarly the increased rate of tissue-change incident to violent activity of function appears to increase the susceptibility to cold; thus any one who has unusually exercised certain muscles will, after exposure, find those muscles become painful, "stiff," tender, and inflamed, while the remaining muscles of the body will have escaped any such manifestations. Buds that have withstood the severest cold of winter are often killed by the late but more moderate frosts of spring, because at this latter period they are in a state of more rapid tissue-change. The egg of the fowl will bear a considerable degree of cold without losing its vitality so long as its evolutionary processes are at a stand-still; but, when the rapid changes of structure incident to embryonic development have been set up, exposure even to the ordinary atmospheric temperature of spring and summer, if at all prolonged, is sufficient to destroy its life.
The greatest security against injury, therefore, from exposure to cold, would seem to be (comparative) structural stability—organic rest. But, in whatever manner to be explained, the fact remains that processes of physiological development may be disastrously embarrassed by the want of a continuous sufficiently elevated temperature, and fatally injured by direct exposure to cold.
It now remains to show that organs undergoing pathological evolution (conservative structural modification) are affected exactly in the same manner by exposure to cold. Speaking, first, theoretically, we find organs thus circumstanced are the seat of an exalted rate of tissue-transformation, of a change additional to that which belongs to the ordinary process of waste and repair, and therefore we should a priori expect to find in them the same liability to inflammation, on exposure, as was observed in organs being rapidly developed physiologically. Speaking practically, we find, a fortiori, that this is actually the case. What is more common, with a patient who is the subject of some chronic organic disease, than to be suddenly cut off by the occurrence of acute inflammation in the affected organ after exposure to cold? Every medical practitioner can answer. In remarking upon the influence of cold as a cause of mortality. Dr. Carpenter, in his "Human Physiology," refers to the Report of the Registrar-General for March, 1855, in which it appears that the rate of mortality, not only in infants and aged persons, but also in those affected with chronic disease, increases during the winter months, and diminishes in summer. The deaths in many instances (in old persons) were due to pneumonia, bronchitis, asthma, and various chronic diseases; so that Dr. Carpenter is led to observe that "cold brings quickly to a fatal termination many maladies which it does not directly induce." Nay, the acute inflammatory attack, under such circumstances, is often enough the first intimation, to the patient, and perhaps to the physician, of the existence of organic change in the affected organ. A most common error, and, as far as I know, a universal one, is to date the real beginning of the disease from the acute inflammation, and ascribe any recognizable lingering symptoms to the acute attack having "lapsed into the chronic form;" when, in fact, the slow, chronic changes of structure were present only in their naturally-designed latent form, long before, and were only made manifest to the patient by the disturbing action of cold.
As we have seen that, in organisms undergoing physiological development, those organs are most liable to be attacked with inflammation after exposure, whose rate of growth happens to be at the time most rapid, so in after-life it is not all the organs in the body that are liable to inflame after exposure, but only those in which pathological evolution is taking place. And this explains why it is, when several persons have been equally exposed, that one suffers from acute pneumonia, another from acute nephritis (kidney-inflammation), another from acute arthritis (joint-inflammation), while some altogether escape any unpleasant effect: these last were organically sound before exposure, and the same after it. In external, visible parts, that are the seat of injury or disease, or that have been wounded by the surgeon's knife, and which are undergoing the process of tissue-repair, we see redness and congestion follow exposure to cold, and often enough hear the patient not only complain of pain, but date its commencement from known exposure, and express his belief—reached as if by instinct—that "cold had settled on the part."
Again, as young animals instinctively dread cold, and as Nature provides them means for warmth, so in individuals undergoing evolution of a pathological kind, we observe a like instinctive dread of exposure, and a liability to be easily "chilled," while means of protection are also instinctively resorted to. The extra quilt at night; the heavy wrapper during the day; the thick woolen under-garments; the flannel "chest-protector;" the late fires in spring, and early ones in autumn, so necessary for the comfort of the invalid—what are they but imitations of the means supplied by Nature for the preservation of warmth in young animals undergoing physiological development?
We have further proof that organs undergoing pathological evolution are liable to be disturbed by cold in the manner referred to, and also that the existence of the evolutionary process is itself one of the conditions without which (in the absence of others) inflammation, after exposure, would not take place, in the fact that attacks of inflammation occur repeatedly in the same organ. Thus, to take a familiar illustration, it has been long ago observed that some people are liable to repeated attacks of inflammation of the lungs (pneumonia). Andral records a case of a patient who had fifteen attacks in eleven years; Chomel has seen ten recurrences, J. P. Frank eleven, and Rust has recorded twenty-eight attacks, in the same individual A patient of Ziemssen's had four attacks in five years. It is also observed that, of the two lungs, the one first affected is most liable to suffer from subsequent attacks. In thirty-five cases of recurrence collected by Grisolle, the return of the disease was noted twenty-five times in the lung first affected. In the other ten, the disease changed sides (see Reynolds's "System of Medicine," vol. iii., p. 613).
The limits of the present paper precluding a very prolonged argument, we leave this part of the subject, hoping that what has been said is sufficient to account for the mortality of pathological processes which, we have said, are designedly conservative.
We may now further follow out the analogy between physiological and pathological evolution, by observing that structures undergoing pathological development (conservative organic modification), like those that are being developed physiologically, manifest an intrinsic tendency, when undisturbed in their progress, to pursue a fixed, typical course to their naturally-designed termination. When permitted to pursue such a typical course, the observed structural changes are exceedingly slow, and are attended with little or no physical suffering.
Let us speak, first, of physiological evolution. And, to begin, let us ask, "How shall we know when physiological development is following its natural course, and when it is not?" There are two striking characteristics which can always here be taken as guides, viz., slowness of organic change, and latency. The physiological growth of tissue is always gradual in its progress, both as regards change of shape, bulk, and variation in physical properties. These go on with an insidious progression that is, for the most part, quite imperceptible to ordinary methods of observation. Natura non facet saltem. Abrupt changes of shape, size, etc., incident to function, are, of course, quite common, but these are only temporary, and quite distinct from the more stable organic changes constituting growth. Indeed, it may be taken as an invariable rule that structural changes of any considerable extent, that occur abruptly and remain permanent, are always unnatural, and are to be attributed to the action, direct or indirect, of some disturbing cause.
Secondly, we notice that the natural course of physiological development is characterized by painlessness—unconsciousness on the part of the individual that any tissue-changes at all are taking place. As the height of perfection in function, as in digestion, for example, consists in ignorance or unconsciousness of the existence of the organs performing it, so is it an invariable quality of every perfectly natural organic change that it should take place without the knowledge of the individual—I mean without any knowledge derived from unpleasant sensations. No argument is needed to support this statement; we will only add that, when physiological organic changes are accompanied with pain, it is always attributable to some injurious influence leaving caused the changes that are taking place to deviate from their natural and typical course.
A third characteristic of undisturbed physiological evolution is this: the developed organs, when their evolution is complete, and indeed during their development, present a typical uniformity of structure; that is to say, organisms whose development has been perfectly natural, provided they are of the same age, sex, species, etc., are alike; and the several organs of different individuals present a uniform standard of size, shape, and functional power, any slight existing differences being so inappreciable as to evade ordinary methods of observation. This uniformity of type, however, will only be observed in wild animals that have led a strictly natural life, untrammeled by domestication, such as ocean and river fish that have not been removed from their natural waters, wild birds, reptiles, insects, and the untamed mammalian animals. So exactly similar in such instances are the nutritive changes of waste and repair, growth and development, that not only are the size and shape uniformly the same, but even the color of the exterior presents the same unvarying uniformity of shade. The spots on the leopard and on the butterfly's wing, the speckles and stripes on the reptile, the scales of the fish, the plumage of the bird, and the fur of quadrupeds, are tinted so precisely alike in different individuals of the same species, age, etc., that we find it difficult to detect the slightest variation. Any appreciable deviation from the standard type must always be attributed to the action of some unusual cause disturbing the normal course of evolution, unnumbered instances of which appear among domesticated animals, where, in fact, uniformity is the exception and variety quite common.
Now, to go back to pathological evolution, we find the three qualities of graduality, latency, and uniformity of type, to belong also to it, i. e., when it has followed its undisturbed typical course. We observe, however, that graduality—slowness of organic change—is common only to so-called chronic pathological changes; in acute organic diseases (those that we have seen destroy life) the change of tissue is rapid; hence an organ undergoing pathological modification that becomes the seat of an acute process (of an acute inflammation) can no longer be said to have followed its designed typical course, and we can no longer anticipate the same attaining of the pathological evolution to its designed conservative, typical completion. The acute disease is accompanied with fever, hence with rapid wasting and reduced assimilation of food; it leaves the whole organism reduced in vital power, and there remain behind inflammatory products which require to be removed; the normal progress of the gradual pathological development has been arrested; the vitality of the part has been weakened; there is set up in it a tendency to degeneration or local death. Indeed, time would fail us to enumerate all the injurious consequences, immediate and remote, general and local, that are liable to follow even a single acute inflammatory attack. No wonder, when such attacks occur more than once, or are repeated over and over again, that the pathologically developing organ fails of reaching its designed conservative termination; it need never surprise us, under such circumstances, that the final result is degeneration and death instead of preservation and repair.
In the several instances (very simple ones) of admitted conservative modifications of structure previously mentioned, we observed that time was an important element. The enlargement of anastomosing arteries that took place after the main vessel had been tied, did so by slow degrees; so did the hypertrophy of the heart that followed more general arterial obstruction; so did the transformation of mucous membrane into skin when exposed to air; and so do all conservative modifications of structure when they have been allowed to pursue, undisturbed, their designed typical course.
Secondly, when typical pathological evolution follows its designed course, it is devoid of symptoms, latent; the tissue-changes going on do not make known their existence by pain or unpleasant sensations. Did space permit I might quote without limit from medical authorities to prove not only the occurrence, but the quite frequent occurrence, of organic changes of structure in their "latent form." The index of almost any text-book on "Pathology," or "Practice," will direct the reader to ample evidence on this point. I will, however, cite one or two well-known authors. Prof. George B. Wood, of Philadelphia, remarks that "sometimes inflammation" (he must refer to sub-acute or chronic inflammation) "runs its accustomed course, so far as relates to its effects upon the textures in which it is seated, with scarcely any of those evidences by which its existence in the interior of the body is usually detected, such as pain, disordered function, and constitutional disturbance. Under such circumstances it is said to be latent, and often escapes detection."
Prof. Austin Flint ("Practice of Medicine," pp. 307, 308) refers to cases of what he calls "spontaneous" or "idiopathic endocarditis" (organic modification of the lining membrane of the heart) "which present the physical signs and anatomical characters of the disease without the first symptom having been noticed either by the patient or his physician." The terms "latent pleurisy," "latent phthisis," "latent pneumonia," etc., are familiar to every pathologist. With regard to this latter disease I cannot refrain from inserting one other citation from the "Works of Dr. Thomas Addison" (see "New Sydenham Society's Publications," article "Pneumonia," p. 11). Dr. Addison remarks that Laennec referred to pneumonia without symptoms as of rare but occasional occurrence, and adds: "I am convinced that these reputed deviations and exceptions, regarded as obscure, are of extremely frequent occurrence; and that they are met with at every period of life, and in every variety of constitution; and that they are very far indeed from being limited to old persons, or to what have been called complicated cases.... Cases with symptoms are in truth themselves the exceptions in a pathological sense; and, although most frequently met with in practice, are in fact cases of complication." This most apt statement is replete with wisdom, and true to Nature. Truly, the simplest form of the disease, that in which the tissue-changes are gradual (chronic), and without symptoms (latent), is rarely met with in practice, because the pathological evolution has followed so closely its designed course undisturbed, that the physician is never sent for and never needed any more than he would be in a case of undisturbed physiological evolution. Both are more or less precarious conditions, liable to disturbance and complication; but, while uncomplicated and undisturbed, they are both equally conservative, equally devoid of symptoms, and seldom come under the surveillance of the practitioner. Thus the supposed "insidious stealth" and "fatal subtlety" of organic disease is, in reality, the normal latency of typical pathological evolution.
It is almost unnecessary to add that latent changes are of necessity slow; hence the two qualities of chronicity and latency go hand-in-hand, and both are wanting in supervening acute inflammatory complications.
The third quality which we have said belongs to organs developed (or developing) physiologically is, conformity of structure to a fixed typical standard.
It may, perhaps, be less easy to point out instances of conformity to a fixed type of structure in pathological formations, for the reason, among others, that pathological evolutionary processes are more often interrupted and made to deviate from their intended type than those which are strictly physiological. Organisms follow the course of physiological evolution easily and happily; pathological evolution is something superadded, and, while conservative, is still the result of unnatural external surroundings, and is therefore less easy and auspicious. Furthermore, we may be less familiar with the finished standard of structure which a typical pathological growth is aiming to reach, than we are with one that is physiological, because the former are more rare than the latter, and hence less frequently observed and studied; physiology occurs in every organism; pathology only in some. Physiological organisms may be observed in great numbers together; pathological ones are exceptional and isolated. The typical standard of physiological development is known, because its existence has been believed in and consequently searched for; the standard type of pathological new formations is not so exactly known, because its existence has not been so universally acknowledged, and hence not so diligently sought after.
Again, organisms undergoing pathological evolution frequently die from the direct effect or remote results of acute inflammation, and here the designed type of structure is obscured by the inflammatory process, so that what it would have been in the absence of inflammation cannot always be made out. True, as we have before seen, organisms undergoing physiological evolution die in the same way, and therefore present the same obscurity. In the latter case, however, we observe that, while the designed type of development is obscured in the inflamed parts, the remainder of the organs have pursued their physiological development unimpaired. In pathological evolution this is not the case; that is to say, the organs remaining not inflamed do not present unimpaired pathological evolution, but, on the contrary, furnish still additional instances of physiological development. It is chiefly, therefore, in cases of accidental sudden death from violence that the designed type of development (both pathological and physiological) can be studied best at all. But here, again, specimens of pathological evolution would occur less often than those that are physiological: first, because the whole number of pathological cases is less than the physiological ones; and, second, because individuals undergoing pathological development are less exposed to the liability of death by violence; they, like young individuals undergoing physiological evolution, require more rest, warmth, and frequent feeding, and are less strong and vigorous, than others whose physiological development has been completed, and who are, therefore, more disposed to cope with the risks and hardships of out-door life and labor, under which circumstances death from violence more frequently occurs.
At any rate, it is nothing else than an axiomatic proposition that similar organisms, impressed with similar stimuli, under similar circumstances, will lead to the development of similar structures. Now, it is evidently only by the rarest possibility that we could meet, in the civilized human subject, with a succession of instances in which all these conditions had prevailed. In man and domesticated animals, it is even observed that physiological growth differs widely, but, within certain limits, in different individuals of the same age, species, etc.: it is only in wild animals and plants that we observe uniformity of type; much less, then, need we expect to find this uniformity in evolutionary processes that are pathological; especially, too, when it is only sought for in man and domestic animals.
Finally, notwithstanding the difficulties I have mentioned, enough subservience to a fixed type on the part of pathological new formations has been observed, especially in cases where the new growth and its cause have been limited and simple, to warrant the assertion that pathological evolution in this respect is analogous with physiological development.
This analogy may be further established by considering various other disturbing conditions (in addition to cold) which act disastrously alike in the two kinds of evolution; but this may be reserved for a subsequent paper, when we may also present a new method of study, based upon the views herein laid down, and by the pursuit of which it is possible the nature, cause, and prevention of disease, may be investigated more after the manner of the exact sciences.
- By Perrault in France, Gaubius in Holland, Porterfield and Simpson in Scotland, Juncker in Germany, and by Nichols and Mead in England.
- Stahl's principal work, in which his system was displayed in its most matured form, was entitled "Theoria Medica vera, Physiologiam et Pathologiam sistens." Printed at Halle, in 1708.
- If it should here be alleged that the "inflammation" is the real disease, and that it accomplishes no good, we answer: Inflammation is the process by which the mechanical injury of contusion is to be repaired. It restores the part, just as the "adhesive inflammation" of surgeons heals up the cut of an incised wound.
- See Carpenter's "Human Physiology," American edition of 1856, pp. 419, 420.
- American edition of 1856, p. 864.
- That processes of pathological development can be latent, like physiological evolution, will be shown hereafter.
- "Practice of Medicine," vol. i., p. 38.
- Dr. Wood, in here using the term "inflammation," is still possessed with the old error (long ago set aside by the researches of Dr. Handfield Jones and others), that the growth of fibrous (connective) tissue (the supposed "effect of inflammation upon the textures in which it is seated"), is always due to inflammation. Really this abnormal growth of fibrous tissue is a "new formation," the result of an evolutionary process, and is found after death from inflammation only because it preceded the inflammatory process, and was by this latter brought to a fatal termination.