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 classic 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 analysis. 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 coarse
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 anticipated 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 masseterica, a shallow concavity on the ramus of the
lower jaw, for the lodgment of the masseter 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 nuchae. 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
principal 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
practitioner 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 practitioner 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 principally 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 title, 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 Japanese should have anticipated Europe in a kind
of rude regional anatomy. I have seen a manikin of Japanese 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 pronounced 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 glasses 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 Treviranus
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 canal
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 illustrated 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 Agassiz 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 illustrates 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
constituent 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 analyzed 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, homogeneous 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 glassy 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 principal 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
constituents.
Passing 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 canals 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 space. 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 illustrated
in the titles 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 anticipating the plasterer in fibro-cartilage,
so we see her beforehand with the glassblower 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 glass 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 multitudes (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 glassy
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 mass of cells, out
of which the harmonious diversity of the organs arranges itself, worm or
man, as God has willed from the beginning.
This differentiation having been effected, each several part assumes its
special office, having a life of its own adjusted to that of other parts
and the whole. “Just as a tree constitutes a mass 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.