to be discouraged; and it appears to me to deserve other treatment
than that adopted by the Quarterly Reviewer, who deals with Mr. Darwin
as an Old Bailey barrister deals with a man against whom he wishes
to obtain a conviction, _per fas aut nefas_, and opens his case by
endeavouring to create a prejudice against the prisoner in the minds
of the jury. In his eagerness to carry out this laudable design, the
Quarterly Reviewer cannot even state the history of the doctrine
of natural selection without an oblique and entirely unjustifiable
attempt to depreciate Mr. Darwin. "To Mr. Darwin," says he, "and
(through Mr. Wallace's reticence) to Mr. Darwin alone, is due the
credit of having first brought it prominently forward and demonstrated
its truth." No one can less desire than I do, to throw a doubt upon
Mr. Wallace's originality, or to question his claim to the honour of
being one of the originators of the doctrine of natural selection; but
the statement that Mr. Darwin has the sole credit of originating the
doctrine because of Mr. Wallace's reticence is simply ridiculous. The
proof of this is, in the first place, afforded by Mr. Wallace himself,
whose noble freedom from petty jealousy in this matter, smaller folk
would do well to imitate; and who writes thus:--"I have felt all my
life, and I still feel, the most sincere satisfaction that Mr. Darwin
had been at work long before me, and that it was not left for me to
attempt to write the 'Origin of Species.' I have long since measured
my own strength, and know well that it would be quite unequal to that
task." So that if there was any reticence at all in the matter, it
was Mr. Darwin's reticence during the long twenty years of study which
intervened between the conception and the publication of his theory,
which gave Mr. Wallace the chance of being an independent discoverer
of the importance of natural selection. And, finally, if it be
recollected that Mr. Darwin's and Mr. Wallace's essays were published
simultaneously in the _Journal of the Linnaean Society_ for 1858, it
follows that the Reviewer, while obliquely depreciating Mr. Darwin's
deserts, has in reality awarded to him a priority which, in legal
strictness, does not exist.
Mr. Mivart, whose opinions so often concur with those of the Quarterly
Reviewer, puts the case in a way, which I much regret to be obliged to
say, is, in my judgment, quite as incorrect; though the injustice may
be less glaring. He says that the theory of natural selection is,
in general, exclusively associated with the name of Mr. Darwin, "on
account of the noble self-abnegation of Mr. Wallace." As I have said,
no one can honour Mr. Wallace more than I do, both for what he has
done and for what he has not done, in his relation to Mr. Darwin. And
perhaps nothing is more creditable to him than his frank declaration
that he could not have written such a work as the "Origin of Species."
But, by this declaration, the person most directly interested in the
matter repudiates, by anticipation, Mr. Mivart's suggestion that Mr.
Darwin's eminence is more or less due to Mr. Wallace's modesty.
XI.
THE GENEALOGY OF ANIMALS.[1]
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.
[Footnote 1: "The Natural History of Creation." By Dr. Ernst Haeckel
(_Natürliche Schöpfungs-Geschichte._--Von Dr. Ernst Haeckel, Professor
an der Universität Jena.) Berlin, 1868.]
Among those, Professor Haeckel, of Jena, is the Coryphaeus. 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 systematizing 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
Linnaeus, 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, is 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 oneself 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 "Gynaecomasty," 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.
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 in the direct influence of
the external conditions of his life for the cause of the development
of the sixth finger and toe in the famous Maltese.
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 organizing 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 recognized 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," "Antecocen-zeit," &c. And he conceives that the
abrupt changes between the Faunae 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 Palaeozoic epoch; and I should
apply a similar argumentation to all other groups of animals.
IV. Professor Haeckel proposes a number of modifications in Taxonomy,
all of which are well worthy of consideration. Thus he establishes a
third primary division of the living world, distinct from both
animals and plants, under the name of the _Protista_, to include the
_Myxomycetes_, the _Diatomaceae_, and the _Labyrinthulae_, which are
commonly regarded as plants, with the _Noctilucae_, the _Flagellata_,
the _Rhizopoda_, the _Protoplasta_, and the _Monera_, which are most
generally included within the animal world. A like attempt has been
made, by other writers, to escape the inconvenience of calling these
dubious organisms by the name of plant or animal; but I confess,
it appears to me, that the inconvenience which is eluded in one
direction, by this step, is met in two others. Professor Haeckel
himself doubts whether the _Fungi_ ought not to be removed into his
_Protista_. If they are not, indeed, the _Myxomycetes_ render the
drawing of every line of demarcation between _Protista_ and Plants
impossible. But if they are, who is to define the _Fungi_ from the
_Algae_? Yet the sea-weeds are surely, in every respect, plants.
On the other hand, Professor Haeckel puts the sponges among the
_Coelenterata_ (or polypes and corals), with the double inconvenience,
as it appears to me, of separating the sponges from their immediate
kindred, the _Protoplasta_, and destroying the definition of the
_Coelenterata_. So again, the _Infusoria_ possess all the characters
of animality, but it can hardly be said that they are as clearly
allied to the worms as they are to the _Noctilucae_.
On the whole, it appears to me to be most convenient to adhere to
the old plan of calling such of these low forms as are more animal in
habit, _Protozoa_, and such as are more vegetal, _Protophyta_.
Another considerable innovation is the proposition to divide the class
Pisces into the four groups of _Leptocardia, Cyclostomata, Pisces_,
and _Dipneusta_. As regards the establishment of a separate class for
the Lancelet _(Amphioxus)_, I think there can be little doubt of the
propriety of so doing, inasmuch as it is far more different from all
other fishes than they are from one another. And there is much to
be said in favour of the same promotion of the _Cyclostomata_, or
Lampreys and Hags. But considering the close relation of the
Mudfish with the _Ganoidei_, and the wide differences between the
_Elasmobranchii_ and the _Teleostei_, I greatly doubt the propriety of
separating the _Dipneusta_, as a class, from the other _Pisces_.
Professor Haeckel proposes to break up the vertebrate sub-kingdom,
first, into the two provinces of _Leptocardia_ and _Pachycardia;
Amphioxus_ being in the former, and all other vertebrates in the
latter division. The _Pachycardia_ are then divided into _Monorhina_,
which contains the Cyclostome fishes, distinguished by their single
nasal aperture; and _Amphirhina_, comprising the other _Vertebrata_,
which have two nasal apertures. These are further subdivided into
_Anamnia (Pisces, Dipneusta, Amphibia)_ and _Amniota (Reptilia, Aves,
Mammalia)_. This classification undoubtedly expresses many of the most
important facts in vertebrate structure in a clear and compendious
way; whether it is the best that can he adopted remains to be seen.
With much reason the Lemurs are removed altogether from the
_Primates_, under the name of _Prosimiae_. But I am surprised to
find the _Sirenia_ left in one group with the _Cetacea_, and the
_Plesiosauria_ with the _Ichthyosauria_; the ordinal distinctness of
these having, to my mind, been long since fully established.
V. In Professor Haeckel's speculations on Phylogeny, or the genealogy
of animal forms, there is much that is profoundly interesting, and
his suggestions are always supported by sound knowledge and great
ingenuity. Whether one agrees or disagrees with him, one feels that
he has forced the mind into lines of thought in which it is more
profitable to go wrong than to stand still.