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Darwiniana

T >> Thomas Henry Huxley >> Darwiniana




"The doctrine of _epigenesis_ is derived from Harvey: following by
ocular inspection the development of the new being in the Windsor does, he
saw each part appear successively, and taking the moment of
_appearance_ for the moment of _formation_ he imagined
_epigenesis_." (p. 165.)

On the contrary, says M. Flourens (p. 167),

"The new being is formed at a stroke (_tout d'un coup_), as a whole,
instantaneously; it is not formed part by part, and at different times. It
is formed at once at the single _individual_ moment at which the
conjunction of the male and female elements takes place."

It will be observed that M. Flourens uses language which cannot be
mistaken. For him, the labours of Von Baer, of Rathke, of Coste, and their
contemporaries and successors in Germany, France, and England, are
non-existent: and, as Darwin "_imagina_" natural selection, so Harvey
"_imagina_" that doctrine which gives him an even greater claim to the
veneration of posterity than his better known discovery of the circulation
of the blood.

Language such as that we have quoted is, in fact, so preposterous, so
utterly incompatible with anything but absolute ignorance of some of the
best established facts, that we should have passed it over in silence had
it not appeared to afford some clue to M. Flourens' unhesitating, _ à
priori_, repudiation of all forms of the doctrine of progressive
modification of living beings. He whose mind remains uninfluenced by an
acquaintance with the phænomena of development, must indeed lack one of the
chief motives towards the endeavour to trace a genetic relation between the
different existing forms of life. Those who are ignorant of Geology, find
no difficulty in believing that the world was made as it is; and the
shepherd, untutored in history, sees no reason to regard the green mounds
which indicate the site of a Roman camp as aught but part and parcel of the
primæval hillside. So M. Flourens, who believes that embryos are formed
"tout d'un coup," naturally finds no difficulty in conceiving that species
came into existence in the same way.




IV

THE GENEALOGY OF ANIMALS [Footnote: _The Natural History of Creation_.
By Dr. Ernst Haeckel. [_Natürliche Schöpfungs-Geschichte_.--Von Dr.
Ernst Haeckel, Professor an der Universität Jena.] Berlin, 1868.]

[1869]


Considering that Germany now takes the lead of the world in scientific
investigation, and particularly in biology, Mr. Darwin must be well pleased
at the rapid spread of his views among some of the ablest and most
laborious of German naturalists.

Among these, Professor Haeckel, of Jena, is the Coryphæus. I know of no
more solid and important contributions to biology in the past seven years
than Haeckel's work on the "Radiolaria," and the researches of his
distinguished colleague Gegenbaur, in vertebrate anatomy; while in
Haeckel's "Generelle Morphologie" there is all the force, suggestiveness,
and, what I may term the systematising power, of Oken, without his
extravagance. The "Generelle Morphologie" is, in fact, an attempt to put
the Doctrine of Evolution, so far as it applies to the living world, into a
logical form; and to work out its practical applications to their final
results. The work before, us, again, may be said to be an exposition of the
"Generelle Morphologie" for an educated public, consisting, as it does, of
the substance of a series of lectures delivered before a mixed audience at
Jena, in the session 1867-8.

"The Natural History of Creation,"--or, as Professor Haeckel admits it
would have been better to call his work, "The History of the Development or
Evolution of Nature,"--deals, in the first six lectures, with the general
and historical aspects of the question and contains a very interesting and
lucid account of the views of Linnæus, Cuvier, Agassiz, Goethe, Oken, Kant,
Lamarck, Lyell, and Darwin, and of the historical filiation of these
philosophers.

The next six lectures are occupied by a well-digested statement of Mr.
Darwin's views. The thirteenth lecture discusses two topics which are not
touched by Mr. Darwin, namely, the origin of the present form of the solar
system, and that of living matter. Full justice is done to Kant, as the
originator of that "cosmic gas theory," as the Germans somewhat quaintly
call it, which is commonly ascribed to Laplace. With respect to spontaneous
generation, while admitting that there is no experimental evidence in its
favour, Professor Haeckel denies the possibility of disproving it, and
points out that the assumption that it has occurred is a necessary part of
the doctrine of Evolution. The fourteenth lecture, on "Schöpfungs-Perioden
und Schöpfungs-Urkunden," answers pretty much to the famous disquisition on
the "Imperfection of the Geological Record" in the "Origin of Species."

The following five lectures contain the most original matter of any, being
devoted to "Phylogeny," or the working out of the details of the process of
Evolution in the animal and vegetable kingdoms, so as to prove the line of
descent of each group of living beings, and to furnish it with its proper
genealogical tree, or "phylum."

The last lecture considers objections and sums up the evidence in favour of
biological Evolution.

I shall best testify to my sense of the value of the work thus briefly
analysed if I now proceed to note down some of the more important
criticisms which have been suggested to me by its perusal.

I. In more than one place, Professor Haeckel enlarges upon the service
which the "Origin of Species" has done, in favouring what he terms the
"causal or mechanical" view of living nature as opposed to the
"teleological or vitalistic" view. And no doubt it is quite true that the
doctrine of Evolution is the most formidable opponent of all the commoner
and coarser forms of Teleology. But perhaps the most remarkable service to
the philosophy of Biology rendered by Mr. Darwin is the reconciliation of
Teleology and Morphology, and the explanation of the facts of both which
his views offer.

The Teleology which supposes that the eye, such as we see it in man or one
of the higher _Vertebrata_, was made with the precise structure which
it exhibits, for the purpose of enabling the animal which possesses it to
see, has undoubtedly received its death-blow. Nevertheless it is necessary
to remember that there is a wider Teleology, which is not touched by the
doctrine of Evolution, but is actually based upon the fundamental
proposition of Evolution. That proposition is, that the whole world, living
and not living, in the result of the mutual interaction, according to
definite laws, of the forces possessed by the molecules of which the
primitive nebulosity of the universe was composed. If this be true, it is
no less certain that the existing world lay, potentially, in the cosmic
vapour; and that a sufficient intelligence could, from a knowledge of the
properties of the molecules of that vapour, have predicted, say the state
of the Fauna of Britain in 1869, with as much certainty as one can say what
will happen to the vapour of the breath in a cold winter's day.

Consider a kitchen clock, which ticks loudly, shows the hours, minutes, and
seconds, strikes, cries "cuckoo!" and perhaps shows the phases of the moon.
When the clock is wound up, all the phenomena which it exhibits are
potentially contained in its mechanism, and a clever clockmaker could
predict all it will do after an examination of its structure.

If the evolution theory is correct, the molecular structure of the cosmic
gas stands in the same relation to the phenomena of the world as the
structure of the clock to its phenomena.

Now let us suppose a death-watch, living in the clock-case, to be a learned
and intelligent student of its works. He might say, "I find here nothing
but matter and force and pure mechanism from beginning to end," and he
would be quite right. But if he drew the conclusion that the clock was not
contrived for a purpose, he would be quite wrong. On the other hand,
imagine another death-watch of a different turn of mind. He, listening to
the monotonous "tick! tick!" so exactly like his own, might arrive at the
conclusion that the clock was itself a monstrous sort of death-watch, and
that its final cause and purpose was to tick. How easy to point to the
clear relation of the whole mechanism to the pendulum, to the fact that the
one thing the clock did always and without intermission was to tick, and
that all the rest of its phenomena were intermittent and subordinate to
ticking! For all this, it is certain that kitchen clocks are not contrived
for the purpose of making a ticking noise.

Thus the teleological theorist would be as wrong as the mechanical
theorist, among our death-watches; and, probably, the only death-watch who
would be right would be the one who should maintain that the sole thing
death-watches could be sure about was the nature of the clock-works and the
way they move; and that the purpose of the clock lay wholly beyond the
purview of beetle faculties.

Substitute "cosmic vapour" for "clock," and "molecules" for "works," and
the application of the argument is obvious. The teleological and the
mechanical views of nature are not, necessarily, mutually exclusive. On the
contrary, the more purely a mechanist the speculator is, the more firmly
does he assume a primordial molecular arrangement, of which all the
phenomena of the universe are the consequences; and the more completely is
he thereby at the mercy of the teleologist, who can always defy him to
disprove that this primordial molecular arrangement was not intended to
evolve the phenomena of the universe. On the other hand, if the teleologist
assert that this, that, or the other result of the working of any part of
the mechanism of the universe is its purpose and final cause, the mechanist
can always inquire how he knows that it is more than an unessential
incident--the mere ticking of the clock, which he mistakes for its
function. And there seems to be no reply to this inquiry, any more than to
the further, not irrational, question, why trouble one's self about matters
which are out of reach, when the working of the mechanism itself, which is
of infinite practical importance, affords scope for all our energies?

Professor Haeckel has invented a new and convenient name "Dysteleology,"
for the study of the "purposelessnesses" which are observable in living
organisms--such as the multitudinous cases of rudimentary and apparently
useless structures. I confess, however, that it has often appeared to me
that the facts of Dysteleology cut two ways. If we are to assume, as
evolutionists in general do, that useless organs atrophy, such cases as the
existence of lateral rudiments of toes, in the foot of a horse, place us in
a dilemma. For, either these rudiments are of no use to the animal, in
which case, considering that the horse has existed in its present form
since the Pliocene epoch, they surely ought to have disappeared; or they
are of some use to the animal, in which case they are of no use as
arguments against Teleology. A similar, but still stronger, argument may be
based upon the existence of teats, and even functional mammary glands, in
male mammals. Numerous cases of "Gynæcomasty," or functionally active
breasts in men, are on record, though there is no mammalian species
whatever in which the male normally suckles the young. Thus, there can be
little doubt that the mammary gland was as apparently useless in the
remotest male mammalian ancestor of man as in living men, and yet it has
not disappeared. Is it then still profitable to the male organism to retain
it? Possibly; but in that case its dysteleological value is gone.
[Footnote: The recent discovery of the important part played by the Thyroid
gland should be a warning to all speculators about useless organs. 1893.]

II. Professor Haeckel looks upon the causes which have led to the present
diversity of living nature as twofold. Living matter, he tells us, is urged
by two impulses: a centripetal, which tends to preserve and transmit the
specific form, and which he identifies with heredity; and a centrifugal,
which results from the tendency of external conditions to modify the
organism and effect its adaptation to themselves. The internal impulse is
conservative, and tends to the preservation of specific, or individual,
form; the external impulse is metamorphic, and tends to the modification of
specific, or individual, form.

In developing his views upon this subject, Professor Haeckel introduces
qualifications which disarm some of the criticisms I should have been
disposed to offer; but I think that his method of stating the case has the
inconvenience of tending to leave out of sight the important fact--which is
a cardinal point in the Darwinian hypothesis--that the tendency to vary, in
a given organism, may have nothing to do with the external conditions to
which that individual organism is exposed, but may depend wholly upon
internal conditions. No one, I imagine, would dream of seeking for the
cause of the development of the sixth finger and toe in the famous Maltese,
in the direct influence of the external conditions of his life.

I conceive that both hereditary transmission and adaptation need to be
analysed into their constituent conditions by the further application of
the doctrine of the Struggle for Existence. It is a probable hypothesis,
that what the world is to organisms in general, each organism is to the
molecules of which it is composed. Multitudes of these, having diverse
tendencies, are competing with one another for opportunity to exist and
multiply; and the organism, as a whole, is as much the product of the
molecules which are victorious as the Fauna, or Flora, of a country is the
product of the victorious organic beings in it.

On this hypothesis, hereditary transmission is the result of the victory of
particular molecules contained in the impregnated germ. Adaptation to
conditions is the result of the favouring of the multiplication of those
molecules whose organising tendencies are most in harmony with such
conditions. In this view of the matter, conditions are not actively
productive, but are passively permissive; they do not cause variation in
any given direction, but they permit and favour a tendency in that
direction which already exists.

It is true that, in the long run, the origin of the organic molecules
themselves, and of their tendencies, is to be sought in the external world;
but if we carry our inquiries as far back as this, the distinction between
internal and external impulses vanishes. On the other hand, if we confine
ourselves to the consideration of a single organism, I think it must be
admitted that the existence of an internal metamorphic tendency must be as
distinctly recognised as that of an internal conservative tendency; and
that the influence of conditions is mainly, if not wholly, the result of
the extent to which they favour the one, or the other, of these tendencies.

III. There is only one point upon which I fundamentally and entirely
disagree with Professor Haeckel, but that is the very important one of his
conception of geological time, and of the meaning of the stratified rocks
as records and indications of that time. Conceiving that the stratified
rocks of an epoch indicate a period of depression, and that the intervals
between the epochs correspond with periods of elevation of which we have no
record, he intercalates between the different epochs, or periods, intervals
which he terms "Ante-periods." Thus, instead of considering the Triassic,
Jurassic, Cretaceous, and Eocene periods, as continuously successive, he
interposes a period before each, as an "Antetrias-zeit," "Antejura-zeit,"
"Antecreta-zeit," "Anteo-cenzeit," &c. And he conceives that the abrupt
changes between the Faunæ of the different formations are due to the lapse
of time, of which we have no organic record, during their "Ante-periods."

The frequent occurrence of strata containing assemblages of organic forms
which are intermediate between those of adjacent formations, is, to my
mind, fatal to this view. In the well-known St. Cassian beds, for example,
Palaeozoic and Mesozoic forms are commingled, and, between the Cretaceous
and the Eocene formations, there are similar transitional beds. On the
other hand, in the middle of the Silurian series, extensive unconformity of
the strata indicates the lapse of vast intervals of time between the
deposit of successive beds, without any corresponding change in the Fauna.

Professor Haeckel will, I fear, think me unreasonable, if I say that he
seems to be still overshadowed by geological superstitions; and that he
will have to believe in the completeness of the geological record far less
than he does at present. He assumes, for example, that there was no dry
land, nor any terrestrial life, before the end of the Silurian epoch,
simply because, up to the present time, no indications of fresh water, or
terrestrial organisms, have been found in rocks of older date. And, in
speculating upon the origin of a given group, he rarely goes further back
than the "Ante-period," which precedes that in which the remains of animals
belonging to that group are found. Thus, as fossil remains of the majority
of the groups of _Reptilia_ are first found in the Trias, they are
assumed to have originated in the "Antetriassic" period, or between the
Permian and Triassic epochs.

I confess this is wholly incredible to me. The Permian and the Triassic
deposits pass completely into one another; there is no sort of
discontinuity answering to an unrecorded "Antetrias"; and, what is more, we
have evidence of immensely extensive dry land during the formation of these
deposits. We know that the dry land of the Trias absolutely teemed with
reptiles of all groups except Pterodactyles, Snakes, and perhaps Tortoises;
there is every probability that true Birds existed, and _Mammalia_
certainly did. Of the inhabitants of the Permian dry land, on the contrary,
all that have left a record are a few lizards. Is it conceivable that these
last should really represent the whole terrestrial population of that time,
and that the development of Mammals, of Birds, and of the highest forms of
Reptiles, should have been crowded into the time during which the Permian
conditions quietly passed away, and the Triassic conditions began? Does not
any such supposition become in the highest degree improbable, when, in the
terrestrial or fresh-water Labyrinthodonts, which lived on the land of the
Carboniferous epoch, as well as on that of the Trias, we have evidence that
one form of terrestrial life persisted, throughout all these ages, with no
important modification? For my part, having regard to the small amount of
modification (except in the way of extinction) which the Crocodilian,
Lacertilian, and Chelonian _Reptilia_ have undergone, from the older
Mesozoic times to the present day, I cannot but put the existence of the
common stock from which they sprang far back in the Palæozoic epoch; and I
should apply a similar argumentation to all other groups of animals.

[The remainder of this essay contains a discussion of questions of taxonomy
and phylogeny, which is now antiquated. I have reprinted the considerations
about the reconciliation of Teleology with Morphology, about
"Dysteleology," and about the struggle for existence within the organism,
because it has happened to me to be charged with overlooking them.

In discussing Teleology, I ought to have pointed out, as I have done
elsewhere (_Life and Letters of Charles Darwin_, vol. ii. p. 202),
that Paley "proleptically accepted the modern doctrine of Evolution,"
(_Natural Theology_, chap. xxiii.). 1893.]




V

MR. DARWIN'S CRITICS [Footnote: _Contributions to the Theory of Natural
Selection_. By A. R. Wallace. 1870.--2. _The Genesis of Species_.
By St. George Mivart, F.R.S. Second Edition. 1871.--3. _Darwin's Descent
of Man_. Quarterly Review, July 1871.]

[1871]


The gradual lapse of time has now separated us by more than a decade from
the date of the publication of the "Origin of Species"--and whatever may be
thought or said about Mr. Darwin's doctrines, or the manner in which he has
propounded them, this much is certain, that, in a dozen years, the "Origin
of Species" has worked as complete a revolution in biological science as
the "Principia" did in astronomy--and it has done so, because, in the words
of Helmholtz, it contains "an essentially new creative thought." [Footnote:
Helmholtz: _Ueber das Ziel und die Fortschritte der
Naturwissenschaft_. Eröffnungsrede für die Naturforscherversammlung zu
Innsbruck. 1869.] And as time has slipped by, a happy change has come over
Mr. Darwin's critics. The mixture of ignorance and insolence which, at
first, characterised a large proportion of the attacks with which he was
assailed, is no longer the sad distinction of anti-Darwinian criticism.
Instead of abusive nonsense, which merely discredited its writers, we read
essays, which are, at worst, more or less intelligent and appreciative;
while, sometimes, like that which appeared in the "North British Review"
for 1867, they have a real and permanent value.

The several publications of Mr. Wallace and Mr. Mivart contain discussions
of some of Mr. Darwin's views, which are worthy of particular attention,
not only on account of the acknowledged scientific competence of these
writers, but because they exhibit an attention to those philosophical
questions which underlie all physical science, which is as rare as it is
needful. And the same may be said of an article in the "Quarterly Review"
for July 1871, the comparison of which with an article in the same Review
for July 1860, is perhaps the best evidence which can be brought forward of
the change which has taken place in public opinion on "Darwinism."

The Quarterly Reviewer admits "the certainty of the action of natural
selection" (p. 49); and further allows that there is an _à priori_
probability in favour of the evolution of man from some lower animal form,
if these lower animal forms themselves have arisen by evolution.

Mr. Wallace and Mr. Mivart go much further than this. They are as stout
believers in evolution as Mr. Darwin himself; but Mr. Wallace denies that
man can have been evolved from a lower animal by that process of natural
selection which he, with Mr. Darwin, holds to have been sufficient for the
evolution of all animals below man; while Mr. Mivart, admitting that
natural selection has been one of the conditions of the evolution of the
animals below man, maintains that natural selection must, even in their
case, have been supplemented by "some other cause"--of the nature of which,
unfortunately, he does not give us any idea. Thus Mr. Mivart is less of a
Darwinian than Mr. Wallace, for he has less faith in the power of natural
selection. But he is more of an evolutionist than Mr. Wallace, because Mr.
Wallace thinks it necessary to call in an intelligent agent--a sort of
supernatural Sir John Sebright--to produce even the animal frame of man;
while Mr. Mivart requires no Divine assistance till he comes to man's soul.

Thus there is a considerable divergence between Mr. Wallace and Mr. Mivart.
On the other hand, there are some curious similarities between Mr. Mivart
and the Quarterly Reviewer, and these are sometimes so close, that, if Mr.
Mivart thought it worth while, I think he might make out a good case of
plagiarism against the Reviewer, who studiously abstains from quoting him.

Both the Reviewer and Mr. Mivart reproach Mr. Darwin with being, "like so
many other physicists," entangled in a radically false metaphysical system,
and with setting at nought the first principles of both philosophy and
religion. Both enlarge upon the necessity of a sound philosophical basis,
and both, I venture to add, make a conspicuous exhibition of its absence.
The Quarterly Reviewer believes that man "differs more from an elephant or
a gorilla than do these from the dust of the earth on which they tread,"
and Mr. Mivart has expressed the opinion that there is more difference
between man and an ape than there is between an ape and a piece of granite.
[Footnote: See the _Tablet_ for March 11, 1871.]

And even when Mr. Mivart (p. 86) trips in a matter of anatomy, and creates
a difficulty for Mr. Darwin out of a supposed close similarity between the
eyes of fishes and cephalopods, which (as Gegenbaur and others have clearly
shown) does not exist, the Quarterly Reviewer adopts the argument without
hesitation (p. 66).

There is another important point, however, in which it is hard to say
whether Mr. Mivart diverges from the Quarterly Reviewer or not.

The Reviewer declares that Mr. Darwin has, "with needless opposition, set
at nought the first principles of both philosophy and religion" (p. 90).

It looks, at first, as if this meant, that Mr. Darwin's views being false,
the opposition to "religion" which flows from them must be needless. But I
suspect this is not the right view of the meaning of the passage, as Mr.
Mivart, from whom the Quarterly Reviewer plainly draws so much inspiration,
tells us that "the consequences which have been drawn from evolution,
whether exclusively Darwinian or not, to the prejudice of religion, by no
means follow from it, and are in fact illegitimate" (p. 5).

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