series of eloquent tributes have been paid to the merits of that great
man by successive Hunterian orators. I will not delay the commencement
of the proper subject of this course by endeavouring to speak of Hunter
either as a philosopher, a physiologist, or a surgeon, but I cannot
refrain from making a passing allusion to his work in relation to the
special subject of these lectures--_Comparative Anatomy_. And even this
would have been superfluous, after the able analysis of Hunter’s work in
this branch of science contributed by Professor Owen to the fourth
volume of Palmer’s edition of his collected writings, if it had not been
for the vast elucidation of the nature and amount of that work by the
subsequent publication of the two closely-printed octavo volumes of
_Essays and Observations on Natural History, Anatomy, Physiology,
Psychology, and Geology, by John Hunter, being his Posthumous Papers on
those Subjects_, arranged and revised by Professor Owen (1861).
Hunter’s reputation has suffered grievously from the extreme difficulty
he always met with in giving adequate expression to his ideas. Mr.
Clift, who acted for a time as his amanuensis, has told us how he has
often “written the same page for him at least half a dozen times over,
with corrections and transpositions almost without end;” and those who
are familiar with his writings must own that, after all this labour, the
result was often far from satisfactory. Hunter was himself painfully
aware of the deficiency. This it is which has detracted much from the
estimate in which many of his published works are held, and it is this
which was, I suspect, the reason why his published writings bear so
small a proportion to the vast mass of rough manuscript which he left
behind him, especially on the subjects with which we are at present
engaged.
The perusal of the work just mentioned will show how, while occupied
with a large and anxious practice--in itself labour enough for ordinary
men--while cultivating with what I might describe as a passionate energy
the sciences of physiology and pathology, while collecting and arranging
a museum such as never has been formed before or since by a single
individual, he had also carefully recorded a series of dissections of
different species of animals which, as his learned editor justly says,
if “published _seriatim_, would not only have vied with the labours of
Daubenton as recorded in the _Histoire Naturelle_ of Buffon, or with the
_Comparative Dissections_ of Vicq d’Azyr, which are inserted in the
early volumes of the _Encyclopédie Méthodique_ and in the _Mémoires de
l’Académie Royale de France_, but they would have exceeded them both
together.”[16] In fact they would have established Hunter’s fame as by
far the greatest contributor to the knowledge of animal structure of his
time, and, what is more important, would have aided most materially in
the advancement and diffusion of that knowledge.
The work as now published contains notes of dissections, more or less
complete, of no less than 129 species of mammalia, 80 species of birds,
20 species of reptiles, 9 of amphibia, and 19 of fishes, besides
numerous invertebrated animals of various classes; and these appear to
be by no means the entire series of dissections left by Hunter.
The fate of the original manuscripts forms a sad page in the history of
our science, and, I must also add, in the history of a man whom our
Profession, and this College especially, might otherwise have regarded
with feelings of respect and gratitude. Exactly thirty years after
Hunter’s death, his brother-in-law and executor, Sir Everard Home, who
had retained possession of them when the collection was transferred to
the College, committed them all to the flames. The use that he had made
of them in composing the lectures which he delivered from this chair,
though often previously surmised, has become but too obvious since the
publication of this work.[17]
Happily, Hunter’s devoted assistant and friend, the assiduous and
excellent custodian of his collection for nearly fifty years, William
Clift, had occupied himself in the interval between Hunter’s death and
the removal of the manuscripts to Sir Everard Home’s house, in making
copious extracts from these precious documents. The publication of these
extracts, nearly seventy years after their author had passed away,
however meritorious a labour on the part of their editor, can
unfortunately do little to regain for Hunter that place among the
leaders of science which his own untimely death, and the negligence, or
worse, of his executor had deprived him. Highly original and valuable as
are the observations contained in these volumes, they have by this time
been nearly all anticipated by others. A crowd of workers in the same
field, pressing in from all directions, have covered the ground which
ought to have been occupied by the figure of Hunter, and from which no
tardy recognition of his merits can ever dispossess them. We shall still
continue to look to Cuvier and to Meckel as the main sources of our
modern knowledge of comparative anatomy, and not to Hunter. Let us,
though, never forget that our illustrious countryman had, before their
time, collected materials for a work which needed but the finishing
touches to have made it one of the greatest, most durable, and valuable
contributions ever made by any one man to the advancement of the science
of comparative anatomy.
* * * * *
The present course of lectures, as just said, are intimately associated
with the museum; their annual delivery was one of the conditions on
which the care of the Hunterian collection was entrusted by the
Government to our College, and it was expressly stipulated that they
should be “illustrated by the preparations.” I am bound, therefore, in
my choice of subjects to consider what the museum teaches, and what it
does not teach. The museum teaches one subject, and, primarily, only one
subject--namely, the variations in the form and relations of the
different parts or organs of which the bodies of various animals are
composed. In brief, it teaches _Animal Morphology_, which is nearly
synonymous with _Comparative Anatomy_.
Now, _morphology_, I need hardly say, is not _physiology_, though it may
be one of the foundations on which that complex science is based. But,
contrary as it may seem to some of the most cherished notions of the
founder of the collection, an anatomical museum can scarcely do more in
teaching physiology than a collection of minerals can in teaching
chemistry. The physiologist should certainly be well versed in the
nature of the materials and organs by which the functions of which he
treats are carried on--having, indeed, need of all the help he can
obtain from all quarters in the solution of the difficult problems which
come before him; but his science is, in the main, experimental. Whether
it be from the inherent difficulties that attend such inductions, or
from the hasty and illogical way in which they have often been made,
hitherto a large proportion of the attempts to solve physiological
inquiries by an appeal to morphology alone have ended in failure, often
of a mortifying character. We still have to confess our ignorance of the
purpose and application of innumerable most obvious and striking
modifications of structure, which no amount of reasoning or guessing,
without actual observation on the living organism, seems able to remove.
I am speaking of physiology in the sense in which the term is ordinarily
restricted. There is a more general and higher physiology, to which I
shall refer presently, to elucidate which morphology is one of the most
essential aids.
When morphology was first cultivated with anything like scientific
precision, views since called “teleological,” exclusively prevailed.
Every animal was looked upon as an isolated machine; every part of that
animal was supposed to have been formed expressly for carrying on the
economy of that particular species or individual in the most efficient
manner, without any reference to other species or individuals. If
anything further was looked for in anatomising an animal beyond the mere
gratification of curiosity or love of knowledge for its own sake, it was
_direct adaptation to purpose_.
Many, indeed, are the curious speculations indulged in by anatomists of
this school, impelled, as they appear always to have been, to find an
immediate use for every modification of form. In numerous instances
these were mere conjectures, which an enlarged knowledge of the habits
and economy of the animal treated of, or of kindred species, showed to
be fallacious.
As time went on, however, and men began to obtain a deeper insight into
these subjects, resemblances either between the whole structure or
between particular parts of different animals, which could not be
explained on the utilitarian principle, became strikingly obvious.
Moreover, such things as rudimentary and functionless organs in one
animal, representing developed or functional organs in another, became
known in the further prosecution of morphology. Then the idea gradually
dawned that there was some “secret bond” which linked creature to
creature, and which permitted deviation only to a certain point from a
certain given pattern of construction.
This was the doctrine of _type_ or _common plan_. A “type” or a “common
plan” for each natural group of the animal kingdom was supposed to have
influenced, or to have been held in view at, the creation of every
different species composing that group, the deviations from this type
being related to the special exigencies of the particular species.
This was a great step in advance when regarded as a mere exposition of
the facts of morphology, and when the idea was not carried out by
fanciful imaginations beyond the point warranted by these facts. Upon
this view many anatomists of great eminence seemed to rest. But still it
explained nothing, accounted for nothing. It gave not even a shadow of a
reason for the resemblances amid diversity found everywhere. It only
asserted that the Creator had imposed certain apparently quite arbitrary
restrictions to His power; but, beyond this almost paradoxical
assertion, it gave no clue to elucidate anything like a theory of
creation.
In the meanwhile, however, the great results arrived at in other
branches of science, the increasing accumulation of facts from various
sources, all tending to show that the orderly and harmonious working of
the whole universe was due to constantly acting causes or laws, acting
now, having acted for immeasurable time past, and, as far as we can see,
about to act for immeasurable time to come,--the great work of the
astronomers and the geologists, leading to “the general conception of
some _great principle of orderly evolution_, according to which the
present as well as past systems of existence have been produced out of
preceding orders of things,”[18]--could not pass unnoticed by the
biologists.
First with a faint and uncertain sound, but in later times more boldly
and confidently, an hypothesis has been propounded which does profess to
account for some, at least, of the facts of animal creation, and to
afford a guide to the solution of the problem, if not of the original
beginnings, at least of the present diversities, as well as
resemblances, among the animal and vegetable life on the globe.
This theory has for its basis that the secret bond of union is not
“conformity to type,” is no ideal to which the operations of Creation
were limited, but is one of actual consanguinity, or, as otherwise
expressed, “genetic affinity.”
The fundamental part of the theory is that, as individuals are known to
come into being by a process of generation acting according to fixed and
certain laws, the same to-day and yesterday and to-morrow, in like
manner have races, varieties, species, and other larger groups of
animals and plants come into being--that the species existing at any one
period on the earth’s surface are, in fact, the direct descendants,
modified according to definite laws, of the creatures inhabiting the
earth in previous periods.
The theory of orderly evolution already applied to most of the phenomena
of the physical world has thus been also applied to organic nature.
This hypothesis, originally promulgated in a comparatively crude form by
De Maillet, Erasmus Darwin, and Lamarck, and more recently advocated by
the author of the _Vestiges of Creation_,[19] for a long time found
little favour with English naturalists of eminence. Indeed, so late as
1856, Baden Powell, in his masterly essay “On the Philosophy of
Creation,” arguing with great force “that one grand overruling
principle, the universality of law, order, and continuity, presiding as
powerfully over the earlier stages of creation as during its continuance
at the present moment, applies equally to organic as to inorganic
existence,” can find little support from the writings of any who had
made the diversities of organic life their special study. It was, in
fact, in opposition to the views then held by most naturalists, and
chiefly from a profound and philosophical analysis of the laws which
govern the physical universe, that, reasoning from the general to the
special, he came to the conclusion that “at least, _as a philosophical
conjecture_, the idea of transmutation of species under adequate changes
of condition, and in incalculably long periods of time, seems supported
by fair analogy and probability.”
Very shortly after, however, these views received an immense stimulus by
the working out of a necessary complement to the main theory, one which
was absolutely essential to its general reception--namely, a suggestion
of a possible and intelligible _modus operandi_--almost simultaneously
by the studies of Wallace amid the exuberant displays of nature in the
unexplored forests of the Malayan archipelago, and by the patient
accumulation and careful and candid examination of fact upon fact, drawn
from every branch of biological science, and all converging on the
theory of “_the origin of species by means of natural selection_,” by
the great naturalist[20] whose name is now so thoroughly identified with
the entire transmutation hypothesis, that already in the German
booksellers’ catalogues “Darwinismus” is made a prominent subdivision in
their classification of scientific literature; and in this country
“Darwinism” is the term popularly, if not quite correctly, applied to
the general doctrine of “organic evolution.”
In reference to the effect which the publication of these researches has
produced, the learned and judicious President of the Linnæan Society,
Mr. Bentham, in his last anniversary address, says that “the
investigation of the origin, development, and life history of species or
races has been termed _the great problem of the day_”; and the impulse
they have given to the study of biology in general, and to our special
branch in particular, is not exaggerated by the eminent German anatomist
Gegenbaur in stating, in a work just published, that “_the theory of
descent will begin a new period in the history of comparative anatomy_.”
On the other hand, it happened rather unfortunately that popular views
of natural theology, probably through the great influence of a famous
work published during what I have described as the first or “utility”
stage of morphology, have attached themselves more or less to the ideas
of that period, and well-meaning but mistaken persons regard with
aversion and alarm the modern theories which are, to a certain extent,
subversive of those ideas. I have no hesitation in saying _mistaken_,
for it is perfectly evident that all arguments as to “the power, wisdom,
and goodness of the Creator,” derived from an animal structure not
miraculously created, but produced by the ordinary laws of generation,
as all known animal structures are, must be entirely and equally valid,
whether the laws producing that structure have been operating for a
shorter or longer period.
As Professor Asa Gray has well put it, “If the argument from structure
to design is convincing when drawn from a particular animal, say a
Newfoundland dog, and is not weakened by the knowledge that this dog
came from similar parents, would it be weakened if, in tracing his
genealogy, it were ascertained that he was a remote descendant of the
mastiff or some other breed, or that both these and other breeds came
(as is suspected) from some wolf? If not, how is the argument for design
in the structure of our particular dog affected by the supposition that
his wolfish progenitor came from a post-tertiary wolf, perhaps less
unlike an existing one than the dog in question is to some other of the
numerous existing races of dogs, and that this post-tertiary came from
an equally or more different tertiary wolf? And if the argument from
structure to design is not invalidated by our present knowledge that our
individual dog was developed from a single organic cell, how is it
invalidated by the supposition of an analogous natural descent, through
a long line of connected forms, from a cell, or from some simple animal
existing ages before there were any dogs?”[21]
Those who recognise that the ebb and flow of the tides, the
thunderstorms, the rains, and frosts, are beneficent in their effects,
although the result not of direct miraculous interference, but of
unchanging cosmical laws, have not the right to accuse of want of
reverence the men who affirm that the wonderfully complex and
beautifully adjusted contrivances of animal structure may also have been
brought about through the intervention of agencies of similar nature.
This opposition, moreover, may have done harm in another manner, by
evoking the natural tendency that exists in many earnest and intensely
truth-loving minds to recoil against any display of unphilosophical
dogmatism, and any appeal to passions and prejudices, where reason alone
ought to have sway, and may thus have led in some cases to a too warm
and partial adoption of theories condemned on such grounds.
The rising school of biologists are destined to live in troublous times.
There can be no doubt that many of the questions now opening consequent
upon the rapid and widespread acceptance of the evolution theory, will
give more disquiet to a large class of persons otherwise not indisposed
to welcome the advances of scientific discovery, than was ever given by
the promulgation of the astronomical revelations of the sixteenth
century, or the more recent establishment of the high antiquity of the
earth, and are likely to lead to equally active reprisals.
The astronomers and geologists have in their turn had to confront the
storm--they and their sciences have survived and triumphed; and, on the
other hand, the faith and morality of the world have not suffered. Now
the biologists are standing in the breach. As a part of or necessary
sequel to the great doctrine of organic evolution, the question of the
origin and position of Man will inevitably obtrude itself. In the coming
discussion on this subject, all who take part in it, or alarm themselves
about it, would do well calmly to consider this point. It is one similar
to that just mentioned with regard to the so-called “natural theology.”
Whatever man’s place may be either _in_ or _out_ of nature, whatever
hopes, or fears, or feelings about himself or his race he may have, we
all of us admit that these are quite uninfluenced by our knowledge of
the fact that each individual man comes into the world by the ordinary
processes of generation, according to the same laws which apply to the
development of all organic beings whatever,--that every part of him
which can come under the scrutiny of the anatomist or naturalist has
been evolved according to these regular laws from a simple minute ovum,
indistinguishable to our senses from that of any of the inferior
animals. If this be so--if man is what he is, notwithstanding the
corporeal mode of origin of the individual man, so he will assuredly be
neither less nor more than man, whatever may be shown regarding the
corporeal origin of the whole race, whether this was from the dust of
the earth, or by the modification of some pre-existing animal form.
This, I conceive, is the ground on which those who would maintain
unimpaired the spiritual and moral dignity of the human race may safely
stand.[22]
* * * * *
In 1861 one of the most distinguished of American naturalists wrote:
“Those, if any there be, who regard the derivative hypothesis as
satisfactorily proved must have loose notions as to what proof is. Those
who imagine it can be easily refuted and cast aside must, we think, have
imperfect or very prejudiced conceptions of the facts concerned and of
the questions at issue.” The experience of nine years leaves the case
precisely, in my judgment, as thus stated by Professor Asa Gray.
Anything which assists to throw light upon it, to lead us nearer either
to its acceptance or rejection, is of primary importance to the
biologist. We must not refuse to take it into earnest consideration.
I think, therefore, that it may be worth while to devote a few words to
two objections which are frequently urged, not indeed against this
theory, but against the prominent place I would assign to its
consideration by all who would enter deeply into the philosophy of
biology. Both of these objections are founded upon misconceptions as to
the real nature of the present aspect of the theory of development.
The first, taking its leading idea from the title of Mr. Darwin’s book,
is that it is unprofitable work to trouble ourselves about the _origin_
of species, or, indeed, of anything else. These events of the very
remote past, it is said, are quite beyond our ken; we really can never
know anything certain about them, and had far better occupy ourselves
with things of the present--things which we can really hope to know much
about.
The other, akin to this, has lately been put forth on high authority.
Let the “derivative hypothesis” be granted, the studies of the zoologist
are not thereby in any way affected. “For all intents and purposes of
the descriptive and recording naturalist,” it is said, “species are
constant; they will last our time. When the existing binomial units of
botanical and zoological specific lists cease to show their present
distinctive characters, the _homo sapiens_ of Linnæus will have merged
into another, probably a higher specific form.”[23]
As I have said, both these objections are founded on an entire
misconception of the main question at issue. If the developmental theory
as held by Darwin, Wallace, and their followers is true, the origin of
species is as much a thing of the present as of the past. It is an
essential part of the theory that the laws which have produced the
diversity of organic forms in the world are those by which the world not
only has been, but _is_ governed. They are as constant, ever-acting, and
unchanging as the laws which direct the movements of the clouds or cause
the torrents to flow down from the mountain side. There is no proof
whatever that the laws of variation and natural selection, if such be
the laws which lead to the introduction of new forms and the extinction
of old ones, were ever more potent than they are at present. A large
class of the arguments by which the theory is supported is derived from
observation upon the present phenomena of life. According to the
hypothesis, transitional forms and incipient species are to be met with
everywhere around us. It is this, in fact, which has given rise to the
difficulty zoologists and botanists always meet with in defining the
limits of the various so-called species composing so many groups both
of animals and plants. Until it is settled whether there is an
insensible blending in the conditions expressed by the terms “variety,”
“race,” “subspecies,” “species,” or whether the old idea of the
immutability of species is to be maintained, zoology can hardly be said
to have a philosophical basis.