Medical Essays, 1842-1882 Part 15

The problem of force meets us everywhere, and I prefer to encounter it in the world of physical phenomena before reaching that of living actions. It is only the name for the incomprehensible cause of certain changes known to our consciousness, and a.s.sumed to be outside of it. For me it is the Deity Himself in action.

I can therefore see a large significance in the somewhat bold language of Burdach: "There is for me but one miracle, that of infinite existence, and but one mystery, the manner in which the finite proceeds from the infinite. So soon as we recognize this incomprehensible act as the general and primordial miracle, of which our reason perceives the necessity, but the manner of which our intelligence cannot grasp, so soon as we contemplate the nature known to us by experience in this light, there is for us no other impenetrable miracle or mystery."

Let us turn to a branch of knowledge which deals with certainties up to the limit of the senses, and is involved in no speculations beyond them.

In certain points of view, HUMAN ANATOMY may be considered an almost exhausted science. From time to time some small organ which had escaped earlier observers has been pointed out,--such parts as the tensor tarsi, the otic ganglion, or the Pacinian bodies; but some of our best anatomical works are those which have been cla.s.sic for many generations.

The plates of the bones in Vesalius, three centuries old, are still masterpieces of accuracy, as of art. The magnificent work of Albinus on the muscles, published in 1747, is still supreme in its department, as the constant references of the most thorough recent treatise on the subject, that of Theile, sufficiently show. More has been done in unravelling the mysteries of the fasciae, but there has been a tendency to overdo this kind of material a.n.a.lysis. Alexander Thomson split them up into cobwebs, as you may see in the plates to Velpeau's Surgical Anatomy. I well remember how he used to shake his head over the coa.r.s.e work of Scarpa and Astley Cooper,--as if Denner, who painted the separate hairs of the beard and pores of the skin in his portraits, had spoken lightly of the pictures of Rubens and Vandyk.

Not only has little been added to the catalogue of parts, but some things long known had become half-forgotten. Louis and others confounded the solitary glands of the lower part of the small intestine with those which "the great Brunner," as Haller calls him, described in 1687 as being found in the duodenum. The display of the fibrous structure of the brain seemed a novelty as shown by Spurzheim. One is startled to find the method antic.i.p.ated by Raymond Vieussens nearly two centuries ago. I can hardly think Gordon had ever looked at his figures, though he names their author, when he wrote the captious and sneering article which attracted so much attention in the pages of the "Edinburgh Review."

This is the place, if anywhere, to mention any observations I could pretend to have made in the course of my teaching the structure of the human body. I can make no better show than most of my predecessors in this well-reaped field. The nucleated cells found connected with the cancellated structure of the bones, which I first pointed out and had figured in 1847, and have shown yearly from that time to the present, and the fossa ma.s.seterica, a shallow concavity on the ramus of the lower jaw, for the lodgment of the ma.s.seter muscle, which acquires significance when examined by the side of the deep cavity on the corresponding part in some carnivora to which it answers, may perhaps be claimed as deserving attention. I have also pleased myself by making a special group of the six radiating muscles which diverge from the spine of the axis, or second cervical vertebra, and by giving to it the name stella musculosa nuchaee. But this scanty catalogue is only an evidence that one may teach long and see little that has not been noted by those who have gone before him. Of course I do not think it necessary to include rare, but already described anomalies, such as the episternal bones, the rectus sternalis, and other interesting exceptional formations I have encountered, which have shown a curious tendency to present themselves several times in the same season, perhaps because the first specimen found calls our attention to any we may subsequently meet with.

The anatomy of the scalpel and the amphitheatre was, then, becoming an exhausted branch of investigation. But during the present century the study of the human body has changed its old aspect, and become fertile in new observations. This rejuvenescence was effected by means of two princ.i.p.al agencies,--new methods and a new instrument.

Descriptive anatomy, as known from an early date, is to the body what geography is to the planet. Now geography was pretty well known so long ago as when Arrowsmith, who was born in 1750, published his admirable maps. But in that same year was born Werner, who taught a new way of studying the earth, since become familiar to us all under the name of Geology.

What geology has done for our knowledge of the earth, has been done for our knowledge of the body by that method of study to which is given the name of General Anatomy. It studies, not the organs as such, but the elements out of which the organs are constructed. It is the geology of the body, as that is the general anatomy of the earth. The extraordinary genius of Bichat, to whom more than any other we owe this new method of study, does not require Mr. Buckle's testimony to impress the pract.i.tioner with the importance of its achievements. I have heard a very wise physician question whether any important result had accrued to practical medicine from Harvey's discovery of the circulation. But Anatomy, Physiology, and Pathology have received a new light from this novel method of contemplating the living structures, which has had a vast influence in enabling the pract.i.tioner at least to distinguish and predict the course of disease. We know as well what differences to expect in the habits of a mucous and of a serous membrane, as what mineral substances to look for in the chalk or the coal measures. You have only to read Cullen's description of inflammation of the lungs or of the bowels, and compare it with such as you may find in Laennec or Watson, to see the immense gain which diagnosis and prognosis have derived from general anatomy.

The second new method of studying the human structure, beginning with the labors of Scarpa, Burns, and Colles, grew up princ.i.p.ally during the first third of this century. It does not deal with organs, as did the earlier anatomists, nor with tissues, after the manner of Bichat. It maps the whole surface of the body into an arbitrary number of regions, and studies each region successively from the surface to the bone, or beneath it. This hardly deserves the name of a science, although Velpeau has dignified it with that t.i.tle, but it furnishes an admirable practical way for the surgeon who has to operate on a particular region of the body to study that region. If we are buying a farm, we are not content with the State map or a geological chart including the estate in question. We demand an exact survey of that particular property, so that we may know what we are dealing with. This is just what regional, or, as it is sometimes called, surgical anatomy, does for the surgeon with reference to the part on which his skill is to be exercised. It enables him to see with the mind's eye through the opaque tissues down to the bone on which they lie, as if the skin were transparent as the cornea, and the organs it covers translucent as the gelatinous pulp of a medusa.

It is curious that the j.a.panese should have antic.i.p.ated Europe in a kind of rude regional anatomy. I have seen a manikin of j.a.panese make traced all over with lines, and points marking their intersection. By this their doctors are guided in the performance of acupuncture, marking the safe places to thrust in needles, as we buoy out our ship-channels, and doubtless indicating to learned eyes the spots where incautious meddling had led to those little accidents of shipwreck to which patients are unfortunately liable.

A change of method, then, has given us General and Regional Anatomy.

These, too, have been worked so thoroughly, that, if not exhausted, they have at least become to a great extent fixed and positive branches of knowledge. But the first of them, General Anatomy, would never, have reached this positive condition but for the introduction of that, instrument which I have mentioned as the second great aid to modern progress.

This instrument is the achromatic microscope. For the history of the successive steps by which it became the effective scientific implement we now possess, I must refer you to the work of Mr. Quekett, to an excellent article in the "Penny Cyclopaedia," or to that of Sir David Brewster in the "Encyclopaedia Britannica." It is a most interesting piece of scientific history, which shows how the problem which Biot in 1821 p.r.o.nounced insolvable was in the course of a few years practically solved, with a success equal to that which Dollond had long before obtained with the telescope. It is enough for our purpose that we are now in possession of an instrument freed from all confusions and illusions, which magnifies a thousand diameters,--a million times in surface,--without serious distortion or discoloration of its object.

A quarter of a century ago, or a little more, an instructor would not have hesitated to put John Bell's "Anatomy" and Bostock's "Physiology"

into a student's hands, as good authority on their respective subjects.

Let us not be unjust to either of these authors. John Bell is the liveliest medical writer that I can remember who has written since the days of delightful old Ambroise Pare. His picturesque descriptions and bold figures are as good now as they ever were, and his book can never become obsolete. But listen to what John Bell says of the microscope:

"Philosophers of the last age had been at infinite pains to find the ultimate fibre of muscles, thinking to discover its properties in its form; but they saw just in proportion to the gla.s.ses which they used, or to their practice and skill in that art, which is now almost forsaken."

Dr. Bostock's work, neglected as it is, is one which I value very highly as a really learned compilation, full of original references. But Dr. Bostock says: "Much as the naturalist has been indebted to the microscope, by bringing into view many beings of which he could not otherwise have ascertained the existence, the physiologist has not yet derived any great benefit from the instrument."

These are only specimens of the manner in which the microscope and its results were generally regarded by the generation just preceding our own.

I have referred you to the proper authorities for the account of those improvements which about the year 1830 rendered the compound microscope an efficient and trustworthy instrument. It was now for the first time that a true general anatomy became possible. As early as 1816 Trevira.n.u.s had attempted to resolve the tissues, of which Bichat had admitted no less than twenty-one, into their simple microscopic elements. How could such an attempt succeed, Henle well asks, at a time when the most extensively diffused of all the tissues, the areolar, was not at all understood? All that method could do had been accomplished by Bichat and his followers. It was for the optician to take the next step. The future of anatomy and physiology, as an enthusiastic micrologist of the time said, was in the hands of Messrs. Schieck and Pistor, famous opticians of Berlin.

In those earlier days of which I am speaking, all the points of minute anatomy were involved in obscurity. Some found globules everywhere, some fibres. Students disputed whether the conjunctiva extended over the cornea or not, and worried themselves over Gaultier de Claubry's stratified layers of the skin, or Breschet's blennogenous and chromatogenous organs. The dartos was a puzzle, the central spinal ca.n.a.l a myth, the decidua clothed in fable as much as the golden fleece. The structure of bone, now so beautifully made out,--even that of the teeth, in which old Leeuwenhoek, peeping with his octogenarian eyes through the minute lenses wrought with his own hands, had long ago seen the "pipes,"

as he called them,--was hardly known at all. The minute structure of the viscera lay in the mists of an uncertain microscopic vision. The intimate recesses of the animal system were to the students of anatomy what the anterior of Africa long was to geographers, and the stories of microscopic explorers were as much sneered at as those of Bruce or Du Chailly, and with better reason.

Now what have we come to in our own day? In the first place, the minute structure of all the organs has been made out in the most satisfactory way. The special arrangements of the vessels and the ducts of all the glands, of the air-tubes and vesicles of the lungs, of the parts which make up the skin and other membranes, all the details of those complex parenchymatous organs which had confounded investigation so long, have been lifted out of the invisible into the sight of all observers. It is fair to mention here, that we owe a great deal to the art of minute injection, by which we are enabled to trace the smallest vessels in the midst of the tissues where they are distributed. This is an old artifice of anatomists. The famous Ruysch, who died a hundred and thirty years ago, showed that each of the viscera has its terminal vessels arranged in its own peculiar way; the same fact which you may see ill.u.s.trated in Gerber's figures after the minute injections of Berres. I hope to show you many specimens of this kind in the microscope, the work of English and American hands. Professor Aga.s.siz allows me also to make use of a very rich collection of injected preparations sent him by Professor Hyrtl, formerly of Prague, now of Vienna, for the proper exhibition of which I had a number of microscopes made expressly, by Mr. Grunow, during the past season. All this ill.u.s.trates what has been done for the elucidation of the intimate details of formation of the organs.

But the great triumph of the microscope as applied to anatomy has been in the resolution of the organs and the tissues into their simple const.i.tuent anatomical elements. It has taken up general anatomy where Bichat left it. He had succeeded in reducing the structural language of nature to syllables, if you will permit me to use so bold an image. The microscopic observers who have come after him have a.n.a.lyzed these into letters, as we may call them,--the simple elements by the combination of which Nature spells out successively tissues, which are her syllables, organs which are her words, systems which are her chapters, and so goes on from the simple to the complex, until she binds up in one living whole that wondrous volume of power and wisdom which we call the human body.

The alphabet of the organization is so short and simple, that I will risk fatiguing your attention by repeating it, according to the plan I have long adopted.

A. Cells, either floating, as in the blood, or fixed, like those in the cancellated structure of bone, already referred to. Very commonly they have undergone a change of figure, most frequently a flattening which reduces them to scales, as in the epidermis and the epithelium.

B. Simple, translucent, h.o.m.ogeneous solid, such as is found at the back of the cornea, or forming the intercellular substance of cartilage.

C. The white fibrous element, consisting of very delicate, tenacious threads. This is the long staple textile substance of the body. It is to the organism what cotton is pretended to be to our Southern States.

It pervades the whole animal fabric as areolar tissue, which is the universal packing and wrapping material. It forms the ligaments which bind the whole frame-work together. It furnishes the sinews, which are the channels of power. It enfolds every muscle. It wraps the brain in its hard, insensible folds, and the heart itself beats in a purse that is made of it.

D. The yellow elastic, fibrous element, the caoutchouc of the animal mechanism, which pulls things back into place, as the India-rubber band shuts the door we have opened.

E. The striped muscular fibre,--the red flesh, which shortens itself in obedience to the will, and thus produces all voluntary active motion.

F. The unstriped muscular fibre, more properly the fusiform-cell fibre, which carries on the involuntary internal movements.

G. The nerve-cylinder, a gla.s.sy tube, with a pith of some firmness, which conveys sensation to the brain and the principle which induces motion from it.

H. The nerve-corpuscle, the centre of nervous power.

I. The mucous tissue, as Virchow calls it, common in embryonic structures, seen in the vitreous humor of the adult.

To these add X, granules, of indeterminate shape and size, Y, for inorganic matters, such as the salts of bone and teeth, and Z, to stand as a symbol of the fluids, and you have the letters of what I have ventured to call the alphabet of the body.

But just as in language certain diphthongs and syllables are frequently recurring, so we have in the body certain secondary and tertiary combinations, which we meet more frequently than the solitary elements of which they are composed.

Thus A B, or a collection of cells united by simple structureless solid, is seen to be extensively employed in the body under the name of cartilage. Out of this the surfaces of the articulations and the springs of the breathing apparatus are formed. But when Nature came to the buffers of the spinal column (intervertebral disks) and the washers of the joints (semilunar fibrocartilages of the knee, etc.), she required more tenacity than common cartilage possessed. What did she do? What does man do in a similar case of need? I need hardly tell you. The mason lays his bricks in simple mortar. But the plasterer works some hair into the mortar which he is going to lay in large sheets on the walls. The children of Israel complained that they had no straw to make their bricks with, though portions of it may still be seen in the crumbling pyramid of Darshour, which they are said to have built. I visited the old house on Witch Hill in Salem a year or two ago, and there I found the walls coated with clay in which straw was abundantly mingled;--the old Judaizing witch-hangers copied the Israelites in a good many things.

The Chinese and the Corsicans blend the fibres of amianthus in their pottery to give it tenacity. Now to return to Nature. To make her buffers and washers hold together in the shocks to which they would be subjected, she took common cartilage and mingled the white fibrous tissue with it, to serve the same purpose as the hair in the mortar, the straw in the bricks and in the plaster of the old wall, and the amianthus in the earthen vessels. Thus we have the combination A B C, or fibro-cartilage. Again, the bones were once only gristle or cartilage, A B. To give them solidity they were infiltrated with stone, in the form of salts of lime, an inorganic element, so that bone would be spelt out by the letters A, B, and Y.

If from these organic syllables we proceed to form organic words, we shall find that Nature employs three princ.i.p.al forms; namely, Vessels, Membranes, and Parenchyma, or visceral tissue. The most complex of them can be resolved into a combination of these few simple anatomical const.i.tuents.

Pa.s.sing for a moment into the domain of PATHOLOGICAL ANATOMY, we find the same elements in morbid growths that we have met with in normal structures. The pus-corpuscle and the white blood-corpuscle can only be distinguished by tracing them to their origin. A frequent form of so-called malignant disease proves to be only a collection of altered epithelium-cells. Even cancer itself has no specific anatomical element, and the diagnosis of a cancerous tumor by the microscope, though tolerably sure under the eye of an expert, is based upon accidental, and not essential points,--the crowding together of the elements, the size of the cell-nuclei, and similar variable characters.

Let us turn to PHYSIOLOGY. The microscope, which has made a new science of the intimate structure of the organs, has at the same time cleared up many uncertainties concerning the mechanism of the special functions. Up to the time of the living generation of observers, Nature had kept over all her inner workshops the forbidding inscription, No Admittance! If any prying observer ventured to spy through his magnifying tubes into the mysteries of her glands and ca.n.a.ls and fluids, she covered up her work in blinding mists and bewildering halos, as the deities of old concealed their favored heroes in the moment of danger.

Science has at length sifted the turbid light of her lenses, and blanched their delusive rainbows.

Anatomy studies the organism in s.p.a.ce. Physiology studies it also in time. After the study of form and composition follows close that of action, and this leads us along back to the first moment of the germ, and forward to the resolution of the living frame into its lifeless elements. In this way Anatomy, or rather that branch of it which we call Histology, has become inseparably blended with the study of function.

The connection between the science of life and that of intimate structure on the one hand, and composition on the other, is ill.u.s.trated in the t.i.tles of two recent works of remarkable excellence,--"the Physiological Anatomy" of Todd and Bowman, and the "Physiological Chemistry" of Lehmann.

Let me briefly recapitulate a few of our acquisitions in Physiology, due in large measure to our new instruments and methods of research, and at the same time indicate the limits which form the permanent or the temporary boundaries of our knowledge. I will begin with the largest fact and with the most absolute and universally encountered limitation.

The "largest truth in Physiology" Mr. Paget considers to be "the development of ova through multiplication and division of their cells."

I would state it more broadly as the agency of the cell in all living processes. It seems at present necessary to abandon the original idea of Schwann, that we can observe the building up of a cell from the simple granules of a blastema, or formative fluid. The evidence points rather towards the axiom, Omnis cellula a cellula; that is, the germ of a new cell is always derived from a preexisting cell. The doctrine of Schwann, as I remarked long ago (1844), runs parallel with the nebular theory in astronomy, and they may yet stand or fall together.

As we have seen Nature antic.i.p.ating the plasterer in fibro-cartilage, so we see her beforehand with the gla.s.sblower in her dealings with the cell. The artisan blows his vitreous bubbles, large or small, to be used afterwards as may be wanted. So Nature shapes her hyaline vesicles and modifies them to serve the needs of the part where they are found. The artisan whirls his rod, and his gla.s.s bubble becomes a flattened disk, with its bull's-eye for a nucleus. These lips of ours are all glazed with microscopic tiles formed of flattened cells, each one of them with its nucleus still as plain and relatively as prominent, to the eye of the microscopist, as the bull's-eye in the old-fashioned windowpane.

Everywhere we find cells, modified or unchanged. They roll in inconceivable mult.i.tudes (five millions and more to the cubic millimetre, according to Vierordt) as blood-disks through our vessels.

A close-fitting mail of flattened cells coats our surface with a panoply of imbricated scales (more than twelve thousand millions), as Harting has computed, as true a defence against our enemies as the buckler of the armadillo or the carapace of the tortoise against theirs. The same little protecting organs pave all the great highways of the interior system. Cells, again, preside over the chemical processes which elaborate the living fluids; they change their form to become the agents of voluntary and involuntary motion; the soul itself sits on a throne of nucleated cells, and flashes its mandates through skeins of gla.s.sy filaments which once were simple chains of vesicles. And, as if to reduce the problem of living force to its simplest expression, we see the yolk of a transparent egg dividing itself in whole or in part, and again dividing and subdividing, until it becomes a ma.s.s of cells, out of which the harmonious diversity of the organs arranges itself, worm or man, as G.o.d has willed from the beginning.

This differentiation having been effected, each several part a.s.sumes its special office, having a life of its own adjusted to that of other parts and the whole. "Just as a tree const.i.tutes a ma.s.s arranged in a definite manner, in which, in every single part, in the leaves as in the root, in the trunk as in the blossom, cells are discovered to be the ultimate elements, so is it also with the forms of animal life. Every animal presents itself as a sum of vital unities, every one of which manifests all the characteristics of life."

The mechanism is as clear, as unquestionable, as absolutely settled and universally accepted, as the order of movement of the heavenly bodies, which we compute backward to the days of the observatories on the plains of Shinar, and on the faith of which we regulate the movements of war and trade by the predictions of our ephemeris.

The mechanism, and that is all. We see the workman and the tools, but the skill that guides the work and the power that performs it are as invisible as ever. I fear that not every listener took the significance of those pregnant words in the pa.s.sage I quoted from John Bell,--"thinking to discover its properties in its form." We have discovered the working bee in this great hive of organization. We have detected the cell in the very act of forming itself from a nucleus, of transforming itself into various tissues, of selecting the elements of various secretions. But why one cell becomes nerve and another muscle, why one selects bile and another fat, we can no more pretend to tell, than why one grape sucks out of the soil the generous juice which princes h.o.a.rd in their cellars, and another the wine which it takes three men to drink,--one to pour it down, another to swallow it, and a third to hold him while it is going down. Certain a.n.a.logies between this selecting power and the phenomena of endosmosis in the elective affinities of chemistry we can find, but the problem of force remains here, as everywhere, unsolved and insolvable.