Part 20

Reflex action, the mechanical sympathy, if I may so call it, of distant parts; Instinct, which is crystallized intelligence,--an absolute law with its invariable planes and angles introduced into the sphere of consciousness, as raphides are inclosed in the living cells of plants; Intellect,--the operation of the thinking principle through material organs, with an appreciable waste of tissue in every act of thought, so that our clergymen's blood has more phosphates to get rid of on Monday than on any other day of the week; Will,--theoretically the absolute determining power, practically limited in different degrees by the varying organization of races and individuals, annulled or perverted by different ill-understood organic changes; on all these subjects our knowledge is in its infancy, and from the study of some of them the interdict of the Vatican is hardly yet removed.

I must allude to one or two points in the histology and physiology of the organs of sense. The anterior continuation of the retina beyond the ora serrata has been a subject of much discussion. If H. Muller and Kolliker can be relied upon, this question is settled by recognizing that a layer of cells, continued from the retina, passes over the surface of the zonula Zinnii, but that no proper nervous element is so prolonged forward.

I observe that Kolliker calls the true nervous elements of the retina “the layer of gray cerebral substance.” In fact, the ganglionic corpuscles of each eye may be considered as constituting a little brain, connected with the masses behind by the commissure, commonly called the optic nerve. We are prepared, therefore, to find these two little brains in the most intimate relations with each other, as we find the cerebral hemispheres. We know that they are directly connected by fibres that arch round through the chiasma.

I mention these anatomical facts to introduce a physiological observation of my own, first announced in one of the lectures before the Medical Class, subsequently communicated to the American Academy of Arts and Sciences, and printed in its “Transactions” for February 14, 1860. I refer to the apparent transfer of impressions from one retina to the other, to which I have given the name reflex vision. The idea was suggested to me in consequence of certain effects noticed in employing the stereoscope. Professor William B. Rodgers has since called the attention of the American Scientific Association to some facts bearing on the subject, and to a very curious experiment of Leonardo da Vinci's, which enables the observer to look through the palm of his hand (or seem to), as if it had a hole bored through it. As he and others hesitated to accept my explanation, I was not sorry to find recently the following words in the “Observations on Man” of that acute observer and thinker, David Hartley. “An impression made on the right eye alone by a single object may propagate itself into the left, and there raise up an image almost equal in vividness to itself; and consequently when we see with one eye only, we may, however, have pictures in both eyes.” Hartley, in 1784, had anticipated many of the doctrines which have since been systematized into the theory of reflex actions, and with which I have attempted to associate this act of reflex vision. My sixth experiment, however, in the communication referred to, appears to me to be a crucial one, proving the correctness of my explanation, and I am not aware that it has been before instituted.

Another point of great interest connected with the physiology of vision, and involved for a long time in great obscurity, is that of the adjustment of the eye to different distances. Dr. Clay Wallace of New York, who published a very ingenious little book on the eye about twenty years ago, with vignettes reminding one of Bewick, was among the first, if not the first, to describe the ciliary muscle, to which the power of adjustment is generally ascribed. It is ascertained, by exact experiment with the phacueidoscope, that accommodation depends on change of form of the crystalline lens. Where the crystalline is wanting, as Mr. Ware long ago taught, no power of accommodation remains. The ciliary muscle is generally thought to effect the change of form of the crystalline. The power of accommodation is lost after the application of atropine, in consequence, as is supposed, of the paralysis of this muscle. This, I believe, is the nearest approach to a demonstration we have on this point.

I have only time briefly to refer to Professor Draper's most ingenious theory as to the photographic nature of vision, for an account of which I must refer to his original and interesting Treatise on Physiology.

It were to be wished that the elaborate and very interesting researches of the Marquis Corti, which have revealed such singular complexity of structure in the cochlea of the ear, had done more to clear up its doubtful physiology; but I am afraid we have nothing but hypotheses for the special part it plays in the act of hearing, and that we must say the same respecting the office of the semicircular canals.

The microscope has achieved some of its greatest triumphs in teaching us the changes which occur in the development of the embryo. No more interesting discovery stands recorded in the voluminous literature of this subject than the one originally announced by Martin Barry, afterwards discredited, and still later confirmed by Mr. Newport and others; namely the fact that the fertilizing filament reaches the interior of the ovum in various animals;--a striking parallel to the

## action of the pollen-tube in the vegetable. But beyond the mechanical

facts all is mystery in the movements of organization, as profound as in the fall of a stone or the formation of a crystal.

To the chemist and the microscopist the living body presents the same difficulties, arising from the fact that everything is in perpetual change in the organism. The fibrine of the blood puzzles the one as much as its globules puzzle the other. The difference between the branches of science which deal with space only, and those which deal with space and time, is this: we have no glasses that can magnify time. The figure I here show you a was photographed from an object (pleurosigma angulatum) magnified a thousand diameters, or presenting a million times its natural surface. This other figure of the same object, enlarged from the one just shown, is magnified seven thousand diameters, or forty-nine million times in surface. When we can make the forty-nine millionth of a second as long as its integer, physiology and chemistry will approach nearer the completeness of anatomy.

Our reverence becomes more worthy, or, if you will, less unworthy of its Infinite Object in proportion as our intelligence is lifted and expanded to a higher and broader understanding of the Divine methods of action. If Galen called his heathen readers to admire, the power, the wisdom, the providence, the goodness of the “Framer of the animal body,”--if Mr. Boyle, the student of nature, as Addison and that friend of his who had known him for forty years tell us, never uttered the name of the Supreme Being without making a distinct pause in his speech, in token of his devout recognition of its awful meaning,--surely we, who inherit the accumulated wisdom of nearly two hundred years since the time of the British philosopher, and of almost two thousand since the Greek physician, may well lift our thoughts from the works we study to their great Artificer. These wonderful discoveries which we owe to that mighty little instrument, the telescope of the inner firmament with all its included worlds; these simple formulae by which we condense the observations of a generation in a single axiom; these logical analyses by which we fence out the ignorance we cannot reclaim, and fix the limits of our knowledge,--all lead us up to the inspiration of the Almighty, which gives understanding to the world's great teachers. To fear science or knowledge, lest it disturb our old beliefs, is to fear the influx of the Divine wisdom into the souls of our fellow-men; for what is science but the piecemeal revelation,--uncovering,--of the plan of creation, by the agency of those chosen prophets of nature whom God has illuminated from the central light of truth for that single purpose?

The studies which we have glanced at are preliminary in your education to the practical arts which make use of them,--the arts of healing,--surgery and medicine. The more you examine the structure of the organs and the laws of life, the more you will find how resolutely each of the cell-republics which make up the E pluribus unum of the body maintains its independence. Guard it, feed it, air it, warm it, exercise or rest it properly, and the working elements will do their best to keep well or to get well. What do we do with ailing vegetables? Dr. Warren, my honored predecessor in this chair, bought a country-place, including half of an old orchard. A few years afterwards I saw the trees on his side of the fence looking in good health, while those on the other side were scraggy and miserable. How do you suppose this change was brought about? By watering them with Fowler's solution? By digging in calomel freely about their roots? Not at all; but by loosening the soil round them, and supplying them with the right kind of food in fitting quantities.

Now a man is not a plant, or, at least, he is a very curious one, for he carries his soil in his stomach, which is a kind--of portable flower-pot, and he grows round it, instead of out of it. He has, besides, a singularly complex nutritive apparatus and a nervous system. But recollect the doctrine already enunciated in the language of Virchow, that an animal, like a tree, is a sum of vital unities, of which the cell is the ultimate element. Every healthy cell, whether in a vegetable or an animal, necessarily performs its function properly so long as it is supplied with its proper materials and stimuli. A cell may, it is true, be congenitally defective, in which case disease is, so to speak, its normal state. But if originally sound and subsequently diseased, there has certainly been some excess, deficiency, or wrong quality in the materials or stimuli applied to it. You remove this injurious influence and substitute a normal one; remove the baked coal-ashes, for instance, from the roots of a tree, and replace them with loam; take away the salt meat from the patient's table, and replace it with fresh meat and vegetables, and the cells of the tree or the man return to their duty.

I do not know that we ever apply to a plant any element which is not a natural constituent of the vegetable structure, except perhaps externally, for the accidental purpose of killing parasites. The whole art of cultivation consists in learning the proper food and conditions of plants, and supplying them. We give them water, earths, salts of various kinds such as they are made of, with a chance to help themselves to air and light. The farmer would be laughed at who undertook to manure his fields or his trees with a salt of lead or of arsenic. These elements are not constituents of healthy plants. The gardener uses the waste of the arsenic furnaces to kill the weeds in his walks.

If the law of the animal cell, and of the animal organism, which is built up of such cells, is like that of the vegetable, we might expect that we should treat all morbid conditions of any of the vital unities belonging to an animal in the same way, by increasing, diminishing, or changing its natural food or stimuli.

That is an aliment which nourishes; whatever we find in the organism, as a constant and integral element, either forming part of its structure, or one of the conditions of vital processes, that and that only deserves the name of aliment. I see no reason, therefore, why iron, phosphate of lime, sulphur, should not be considered food for man, as much as guano or poudrette for vegetables. Whether one or another of them is best in any given case,--whether they shall be taken alone or in combination, in large or small quantities, are separate questions. But they are elements belonging to the body, and even in moderate excess will produce little disturbance. There is no presumption against any of this class of substances, any more than against water or salt, provided they are used in fitting combinations, proportions, and forms.

But when it comes to substances alien to the healthy system, which never belong to it as normal constituents, the case is very different. There is a presumption against putting lead or arsenic into the human body, as against putting them into plants, because they do not belong there, any more than pounded glass, which, it is said, used to be given as a poison. The same thing is true of mercury and silver. What becomes of these alien substances after they get into the system we cannot always tell. But in the case of silver, from the accident of its changing color under the influence of light, we do know what happens. It is thrown out, in part at least, under the epidermis, and there it remains to the patient's dying day. This is a striking illustration of the difficulty which the system finds in dealing with non-assimilable elements, and justifies in some measure the vulgar prejudice against mineral poisons.

I trust the youngest student on these benches will not commit the childish error of confounding a presumption against a particular class of agents with a condemnation of them. Mercury, for instance, is alien to the system, and eminently disturbing in its influence. Yet its efficacy in certain forms of specific disease is acknowledged by all but the most sceptical theorists. Even the esprit moqueur of Ricord, the Voltaire of pelvic literature, submits to the time-honored constitutional authority of this great panacea in the class of cases to which he has devoted his brilliant intelligence. Still, there is no telling what evils have arisen from the abuse of this mineral. Dr. Armstrong long ago pointed out some of them, and they have become matters of common notoriety. I am pleased, therefore, when I find so able and experienced a practitioner as Dr. Williams of this city proving that iritis is best treated without mercury, and Dr. Vanderpoel showing the same thing to be true for pericarditis.

Whatever elements nature does not introduce into vegetables, the natural food of all animal life,--directly of herbivorous, indirectly of carnivorous animals,--are to be regarded with suspicion. Arsenic-eating may seem to improve the condition of horses for a time,--and even of human beings, if Tschudi's stories can be trusted,--but it soon appears that its alien qualities are at war with the animal organization. So of copper, antimony, and other non-alimentary simple substances; everyone of them is an intruder in the living system, as much as a constable would be, quartered in our household. This does not mean that they may not, any of them, be called in for a special need, as we send for the constable when we have good reason to think we have a thief under our roof; but a man's body is his castle, as well as his house, and the presumption is that we are to keep our alimentary doors bolted against these perturbing agents.

Now the feeling is very apt to be just contrary to this. The habit has been very general with well-taught practitioners, to have recourse to the introduction of these alien elements into the system on the occasion of any slight disturbance. The tongue was a little coated, and mercury must be given; the skin was a little dry, and the patient must take antimony. It was like sending for the constable and the posse comitatus when there is only a carpet to shake or a refuse-barrel to empty. [Dr. James Johnson advises persons not ailing to take five grains of blue pill with one or two of aloes twice a week for three or four months in the year, with half a pint of compound decoction of sarsaparilla every day for the same period, to preserve health and prolong life. Pract. Treatise on Dis. of Liver, etc. p. 272.] The constitution bears slow poisoning a great deal better than might be expected; yet the most intelligent men in the profession have gradually got out of the habit of prescribing these powerful alien substances in the old routine way. Mr. Metcalf will tell you how much more sparingly they are given by our practitioners at the present time, than when he first inaugurated the new era of pharmacy among us. Still, the presumption in favor of poisoning out every spontaneous reaction of outraged nature is not extinct in those who are trusted with the lives of their fellow-citizens. “On examining the file of prescriptions at the hospital, I discovered that they were rudely written, and indicated a treatment, as they consisted chiefly of tartar emetic, ipecacuanha, and epsom salts, hardly favorable to the cure of the prevailing diarrhoea and dysenteries.” In a report of a poisoning case now on trial, where we are told that arsenic enough was found in the stomach to produce death in twenty-four hours, the patient is said to have been treated by arsenic, phosphorus, bryonia, aconite, nux vomica, and muriatic acid,--by a practitioner of what school it may be imagined.

The traditional idea of always poisoning out disease, as we smoke out vermin, is now seeking its last refuge behind the wooden cannon and painted port-holes of that unblushing system of false scientific pretences which I do not care to name in a discourse addressed to an audience devoted to the study of the laws of nature in the light of the laws of evidence. It is extraordinary to observe that the system which, by its reducing medicine to a name and a farce, has accustomed all who have sense enough to see through its thin artifices to the idea that diseases get well without being “cured,” should now be the main support of the tottering poison-cure doctrine. It has unquestionably helped to teach wise people that nature heals most diseases without help from pharmaceutic art, but it continues to persuade fools that art can arrest them all with its specifics.

It is worse than useless to attempt in any way to check the freest expression of opinion as to the efficacy of any or all of the “heroic” means of treatment employed by practitioners of different schools and periods. Medical experience is a great thing, but we must not forget that there is a higher experience, which tries its results in a court of a still larger jurisdiction; that, namely, in which the laws of human belief are summoned to the witness-box, and obliged to testify to the sources of error which beset the medical practitioner. The verdict is as old as the father of medicine, who announces it in the words, “judgment is difficult.” Physicians differed so in his time, that some denied that there was any such thing as an art of medicine.

One man's best remedies were held as mischievous by another. The art of healing was like soothsaying, so the common people said; “the same bird was lucky or unlucky, according as he flew to the right or left.”

The practice of medicine has undergone great changes within the period of my own observation. Venesection, for instance, has so far gone out of fashion, that, as I am told by residents of the New York Bellevue and the Massachusetts General Hospitals, it is almost obsolete in these institutions, at least in medical practice. The old Brunonian stimulating treatment has come into vogue again in the practice of Dr. Todd and his followers. The compounds of mercury have yielded their place as drugs of all work, and specifics for that very frequent subjective complaint, nescio quid faciam,--to compounds of iodine. [Sir Astley Cooper has the boldness,--or honesty,--to speak of medicines which “are given as much to assist the medical man as his patient.” Lectures (London, 1832), p. 14.] Opium is believed in, and quinine, and “rum,” using that expressive monosyllable to mean all alcoholic cordials. If Moliere were writing now, instead of saignare, purgare, and the other, he would be more like to say, Stimulare, opium dare et potassio-iodizare.

I have been in relation successively with the English and American evacuant and alterative practice, in which calomel and antimony figured so largely that, as you may see in Dr. Jackson's last “Letter,” Dr. Holyoke, a good representative of sterling old-fashioned medical art, counted them with opium and Peruvian bark as his chief remedies; with the moderately expectant practice of Louis; the blood-letting “coup sur coup” of Bouillaud; the contra-stimulant method of Rasori and his followers; the anti-irritant system of Broussais, with its leeching and gum-water; I have heard from our own students of the simple opium practice of the renowned German teacher, Oppolzer; and now I find the medical community brought round by the revolving cycle of opinion to that same old plan of treatment which John Brown taught in Edinburgh in the last quarter of the last century, and Miner and Tully fiercely advocated among ourselves in the early years of the present. The worthy physicians last mentioned, and their antagonist Dr. Gallup, used stronger language than we of these degenerate days permit ourselves. “The lancet is a weapon which annually slays more than the sword,” says Dr. Tully. “It is probable that, for forty years past, opium and its preparations have done seven times the injury they have rendered benefit, on the great scale of the world,” says Dr. Gallup.

What is the meaning of these perpetual changes and conflicts of medical opinion and practice, from an early antiquity to our own time? Simply this: all “methods” of treatment end in disappointment of those extravagant expectations which men are wont to entertain of medical art. The bills of mortality are more obviously affected by drainage, than by this or that method of practice. The insurance companies do not commonly charge a different percentage on the lives of the patients of this or that physician. In the course of a generation, more or less, physicians themselves are liable to get tired of a practice which has so little effect upon the average movement of vital decomposition. Then they are ready for a change, even if it were back again to a method which has already been tried, and found wanting.

Our practitioners, or many of them, have got back to the ways of old Dr. Samuel Danforth, who, as it is well known, had strong objections to the use of the lancet. By and by a new reputation will be made by some discontented practitioner, who, tired of seeing patients die with their skins full of whiskey and their brains muddy with opium, returns to a bold antiphlogistic treatment, and has the luck to see a few patients of note get well under it. So of the remedies which have gone out of fashion and been superseded by others. It can hardly be doubted that they will come into vogue again, more or less extensively, under the influence of that irresistible demand for change just referred to.