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Darwiniana

T >> Thomas Henry Huxley >> Darwiniana




The collector's instinct, strong in Darwin from his childhood, as is
usually the case in great naturalists, turned itself in the direction of
Insects during his residence at Cambridge. In childhood it had been damped
by the moral scruples of a sister, as to the propriety of catching and
killing insects for the mere sake of possessing them, but now it broke out
afresh, and Darwin became an enthusiastic beetle collector. Oddly enough he
took no scientific interest in beetles, not even troubling himself to make
out their names; his delight lay in the capture of a species which turned
out to be rare or new, and still more in finding his name, as captor,
recorded in print. Evidently, this beetle-hunting hobby had little to do
with science, but was mainly a new phase of the old and undiminished love
of sport. In the intervals of beetle-catching, when shooting and hunting
were not to be had, riding across country answered the purpose. These
tastes naturally threw the young undergraduate among a set of men who
preferred hard riding: to hard reading, and wasted the midnight oil upon
other pursuits than that of academic distinction. A superficial observer
might have had some grounds to fear that Dr. Darwin's wrathful prognosis
might yet be verified. But if the eminently social tendencies of a vigorous
and genial nature sought an outlet among a set of jovial sporting friends,
there were other and no less strong proclivities which brought him into
relation with associates of a very different stamp.

Though almost without ear and with a very defective memory for music,
Darwin was so strongly and pleasurably affected by it that he became a
member of a musical society; and an equal lack of natural capacity for
drawing did not prevent him from studying good works of art with much care.

An acquaintance with even the rudiments of physical science was no part of
the requirements for the ordinary Cambridge degree. But there were
professors both of Geology and of Botany whose lectures were accessible to
those who chose to attend them. The occupants of these chairs, in Darwin's
time, were eminent men and also admirable lecturers in their widely
different styles. The horror of geological lectures which Darwin had
acquired at Edinburgh, unfortunately prevented him from going within reach
of the fervid eloquence of Sedgwick; but he attended the botanical course,
and though he paid no serious attention to the subject, he took great
delight in the country excursions, which Henslow so well knew how to make
both pleasant and instructive. The Botanical Professor was, in fact, a man
of rare character and singularly extensive acquirements in all branches of
natural history. It was his greatest pleasure to place his stores of
knowledge at the disposal of the young men who gathered about him, and who
found in him, not merely an encyclopedic teacher but a wise counsellor,
and, in case of worthiness, a warm friend. Darwin's acquaintance with him
soon ripened into a friendship which was terminated only by Henslow's death
in 1861, when his quondam pupil gave touching expression to his sense of
what he owed to one whom he calls (in one of his letters) his "dear old
master in Natural History." (II. p. 217.) It was by Henslow's advice that
Darwin was led to break the vow he had registered against making an
acquaintance with geology; and it was through Henslow's good offices with
Sedgwick that he obtained the opportunity of accompanying the Geological
Professor on one of his excursions in Wales. He then received a certain
amount of practical instruction in Geology, the value of which he
subsequently warmly acknowledged. (I. p. 237.) In another direction,
Henslow did him an immense, though not altogether intentional service, by
recommending him to buy and study the recently published first volume of
Lyell's "Principles." As an orthodox geologist of the then dominant
catastrophic school, Henslow accompanied his recommendation with the
admonition on no account to adopt Lyell's general views. But the warning
fell on deaf ears, and it is hardly too much to say that Darwin's greatest
work is the outcome of the unflinching application to Biology of the
leading idea and the method applied in the "Principles" to geology.
[Footnote: "After my return to England it appeared to me that by following
the example of Lyell in Geology, and by collecting all facts which bore in
any way on the variation of animals and plants under domestication and
nature, some light might perhaps be thrown on the whole subject [of the
origin of species]." (I. p. 83.) See also the dedication of the second
edition of the _Journal of a Naturalist_]. Finally, it was through
Henslow, and at his suggestion, that Darwin was offered the appointment to
the "Beagle" as naturalist.

During the latter part of Darwin's residence at Cambridge the prospect of
entering the Church, though the plan was never formally renounced, seems to
have grown very shadowy. Humboldt's "Personal Narrative," and Herschel's
"Introduction to the Study of Natural Philosophy," fell in his way and
revealed to him his real vocation. The impression made by the former work
was very strong. "My whole course of life," says Darwin in sending a
message to Humboldt, "is due to having read and re-read, as a youth, his
personal narrative." (I. p. 336.) The description of Teneriffe inspired
Darwin with such a strong desire to visit the island, that he took some
steps towards going there--inquiring about ships, and so on.

But, while this project was fermenting, Henslow, who had been asked to
recommend a naturalist for Captain Fitzroy's projected expedition, at once
thought of his pupil. In his letter of the 24th August, 1831, he says: "I
have stated that I consider you to be the best qualified person I know of
who is likely to undertake such a situation. I state this--not on the
supposition of your being a _finished_ naturalist, but as amply
qualified for collecting, observing, and noting anything worthy to be noted
in Natural History.... The voyage is to last two years, and if you take
plenty of books with you, anything you please may be done." (I. p. 193.)
The state of the case could not have been better put. Assuredly the young
naturalist's theoretical and practical scientific training had gone no
further than might suffice for the outfit of an intelligent collector and
note-taker. He was fully conscious of the fact, and his ambition hardly
rose above the hope that he should bring back materials for the scientific
"lions" at home of sufficient excellence to prevent them from turning and
rending him. (I. p. 248.)

But a fourth educational experiment was to be tried. This time Nature took
him in hand herself and showed him the way by which, to borrow Henslow's
prophetic phrase, "anything he pleased might be done."

The conditions of life presented by a ship-of-war of only 242 tons burthen,
would not, _primâ facie_, appear to be so favourable to intellectual
development as those offered by the cloistered retirement of Christ's
College. Darwin had not even a cabin to himself; while, in addition to the
hindrances and interruptions incidental to sea-life, which can be
appreciated only by those who have had experience of them, sea-sickness
came on whenever the little ship was "lively"; and, considering the
circumstances of the cruise, that must have been her normal state.
Nevertheless, Darwin found on board the "Beagle" that which neither the
pedagogues of Shrewsbury, nor the professoriate of Edinburgh, nor the
tutors of Cambridge had managed to give him. "I have always felt that I owe
to the voyage the first real training or education of my mind (I. p. 61);"
and in a letter written as he was leaving England, he calls the voyage on
which he was starting, with just insight, his "second life." (I. p. 214.)
Happily for Darwin's education, the school time of the "Beagle" lasted five
years instead of two; and the countries which the ship visited were
singularly well fitted to provide him with object-lessons, on the nature of
things, of the greatest value.

While at sea, he diligently collected, studied, and made copious notes upon
the surface Fauna. But with no previous training in dissection, hardly any
power of drawing, and next to no knowledge of comparative anatomy, his
occupation with work of this kind--notwithstanding all his zeal and
industry--resulted, for the most part, in a vast accumulation of useless
manuscript. Some acquaintance with the marine _Crustacea_,
observations on _Planariæ_ and on the ubiquitous _Sagitta_, seem
to have been the chief results of a great amount of labour in this
direction.

It was otherwise with the terrestrial phenomena which came under the
voyager's notice: and Geology very soon took her revenge for the scorn
which the much-bored Edinburgh student had poured upon her. Three weeks
after leaving England the ship touched land for the first time at St. Jago,
in the Cape de Verd Islands, and Darwin found his attention vividly engaged
by the volcanic phenomena and the signs of upheaval which the island
presented. His geological studies had already indicated the direction in
which a great deal might be done, beyond collecting; and it was while
sitting beneath a low lava cliff on the shore of this island, that a sense
of his real capability first dawned upon Darwin, and prompted the ambition
to write a book on the geology of the various countries visited. (I. p.
66.) Even at this early date, Darwin must have thought much on geological
topics, for he was already convinced of the superiority of Lyell's views to
those entertained by the catastrophists [Footnote: "I had brought with me
the first volume of Lyell's _Principles of Geology_, which I studied
attentively; and the book was of the highest service to me in many ways.
The very first place which I examined, namely, St. Jago, in the Cape de
Verd Islands, showed me clearly the wonderful superiority of Lyell's manner
of treating Geology, compared with that of any other author whose works I
had with me or ever afterwards read "-(I. p. 62.)]; and his subsequent
study of the tertiary deposits and of the terraced gravel beds of South
America was eminently fitted to strengthen that conviction. The letters
from South America contain little reference to any scientific topic except
geology; and even the theory of the formation of coral reefs was prompted
by the evidence of extensive and gradual changes of level afforded by the
geology of South America; "No other work of mine," he says, "was begun in
so deductive a spirit as this; for the whole theory was thought out on the
West Coast of South America, before I had seen a true coral reef. I had,
therefore, only to verify and extend my views by a careful examination of
living reefs." (I. p. 70.) In 1835, when starting from Lima for the
Galapagos, he recommends his friend, W. D. Fox, to take up geology:--"There
is so much larger a field for thought than in the other branches of Natural
History. I am become a zealous disciple of Mr. Lyell's views, as made known
in his admirable book. Geologising in South America, I am tempted to carry
parts to a greater extent even than he does. Geology is a capital science
to begin with, as it requires nothing but a little reading, thinking, and
hammering." (I. p. 263.) The truth of the last statement, when it was
written, is a curious mark of the subsequent progress of geology. Even so
late as 1836, Darwin speaks of being "much more inclined for geology than
the other branches of Natural History." (I. p. 275.)

At the end of the letter to Mr. Fox, however, a little doubt is expressed
whether zoological studies might not, after all, have been more profitable;
and an interesting passage in the "Autobiography" enables us to understand
the origin of this hesitation.

"During the voyage of the 'Beagle' I had been deeply impressed by
discovering in the Pampean formation great fossil animals covered with
armour like that on the existing armadillos; secondly, by the manner in
which closely-allied animals replace one another in proceeding southwards
over the continent; and, thirdly, by the South American character of most
of the productions of the Galapagos Archipelago, and, more especially, by
the manner in which they differ slightly on each island of the group; some
of the islands appearing to be very ancient in a geological sense.

"It was evident that such facts as these, as well as many others, could
only be explained on the supposition that species gradually become
modified; and the subject haunted me. But it was equally evident that
neither the action of the surrounding conditions, nor the will of the
organisms (especially in the case of plants) could account for the
innumerable cases in which organisms of every kind are beautifully adapted
to their habits of life; for instance, a woodpecker or a tree-frog to climb
trees, or a seed for dispersal by hooks or plumes. I had always been much
struck by such adaptations, and until these could be explained it seemed to
me almost useless to endeavour to prove by indirect evidence that species
have been modified." (I. p. 82.)

The facts to which reference is here made were, without doubt, eminently
fitted to attract the attention of a philosophical thinker; but, until the
relations of the existing with the extinct species and of the species of
the different geographical areas with one another, were determined with
some exactness, they afforded but an unsafe foundation for speculation. It
was not possible that this determination should have been effected before
the return of the "Beagle" to England; and thus the date which Darwin
(writing in 1837) assigns to the dawn of the new light which was rising in
his mind becomes intelligible. [Footnote: I am indebted to Mr. F. Darwin
for the knowledge of a letter addressed by his father to Dr. Otto Zacharias
in 1877 which contains the following paragraph, confirmatory of the view
expressed above: "When I was on board the _Beagle_, I believed in the
permanence of species, but, as far as I can remember, vague doubts
occasionally flitted across my mind. On my return home in the autumn of
1836, I immediately began to prepare my journal for publication, and then
saw how many facts indicated the common descent of species, so that in
July, 1837, I opened a note-book to record any facts which might bear on
the question. But I did not become convinced that species were mutable
until, I think, two or three years had elapsed."]

"In July opened first note-book on Transmutation of Species. Had been
greatly struck from about the month of previous March on character of South
American fossils and species on Galapagos Archipelago. These facts
(especially latter) origin of all my views." (I. p. 276.)

From March, 1837, then, Darwin, not without many misgivings and
fluctuations of opinion, inclined towards transmutation as a provisional
hypothesis. Three months afterwards he is hard at work collecting facts for
the purpose of testing the hypothesis; and an almost apologetic passage in
a letter to Lyell shows that, already, the attractions of biology are
beginning to predominate over those of geology.

"I have lately been sadly tempted to be idle--[Footnote: Darwin generally
uses the word "idle" in a peculiar sense. He means by it working hard at
something he likes when he ought to be occupied with a less attractive
subject. Though it sounds paradoxical, there is a good deal to be said in
favour of this view of pleasant work.]that is, as far as pure Geology is
concerned--by the delightful number of new views which have been coming in
thickly and steadily--on the classification and affinities and instincts of
animals--bearing on the question of species. Note-book after note-book has
been filled with facts which begin to group themselves _clearly_ under
sub-laws." (I. p. 298.)

The problem which was to be Darwin's chief subject of occupation for the
rest of his life thus presented itself, at first, mainly under its
distributional aspect. Why do species present certain relations in space
and in time? Why are the animals and plants of the Galapagos Archipelago so
like those of South America and yet different from them? Why are those of
the several islets more or less different from one another? Why are the
animals of the latest geological epoch in South America similar in
_facies_ to those which exist in the same region at the present day,
and yet specifically or generically different?

The reply to these questions, which was almost universally received fifty
years ago, was that animals and plants were created such as they are; and
that their present distribution, at any rate so far as terrestrial
organisms are concerned, has been effected by the migration of their
ancestors from the region in which the ark stranded after the subsidence of
the deluge. It is true that the geologists had drawn attention to a good
many tolerably serious difficulties in the way of the diluvial part of this
hypothesis, no less than to the supposition that the work of creation had
occupied only a brief space of time. But even those, such as Lyell, who
most strenuously argued in favour of the sufficiency of natural causes for
the production of the phenomena of the inorganic world, held stoutly by the
hypothesis of creation in the case of those of the world of life.

For persons who were unable to feel satisfied with the fashionable
doctrine, there remained only two alternatives--the hypothesis of
spontaneous generation, and that of descent with modification. The former
was simply the creative hypothesis with the creator left out; the latter
had already been propounded by De Maillet and Erasmus Darwin, among others;
and, later, systematically expounded by Lamarck. But in the eyes of the
naturalist of the "Beagle" (and, probably, in those of most sober
thinkers), the advocates of transmutation had done the doctrine they
expounded more harm than good.

Darwin's opinion of the scientific value of the "Zoonomia" has already been
mentioned. His verdict on Lamarck is given in the following passage of a
letter to Lyell (March, 1863):--

"Lastly, you refer repeatedly to my view as a modification of Lamarck's
doctrine of development and progression. If this is your deliberate opinion
there is nothing to be said, but it does not seem so to me. Plato, Buffon,
my grandfather, before Lamarck and others, propounded the _obvious_
view that if species were not created separately they must have descended
from other species, and I can see nothing else in common between the
"Origin" and Lamarck. I believe this way of putting the case is very
injurious to its acceptance, as it implies necessary progression, and
closely connects Wallace's and my views with what I consider, after two
deliberate readings, as a wretched book, and one from which (I well
remember to my surprise) I gained nothing."

"But," adds Darwin with a little touch of banter, "I know you rank it
higher, which is curious, as it did not in the least shake your belief."
(III. p. 14; see also p. 16, "to me it was an absolutely useless book.")

Unable to find any satisfactory theory of the process of descent with
modification in the works of his predecessors, Darwin proceeded to lay the
foundations of his own views independently; and he naturally turned, in the
first place, to the only certainly known examples of descent with
modification, namely, those which are presented by domestic animals and
cultivated plants. He devoted himself to the study of these cases with a
thoroughness to which none of his predecessors even remotely approximated;
and he very soon had his reward in the discovery "that selection was the
keystone of man's success in making useful races of animals and plants."
(I. p. 83.)

This was the first step in Darwin's progress, though its immediate result
was to bring him face to face with a great difficulty. "But how selection
could be applied to organisms living in a state of nature remained for some
time a mystery to me." (I. p. 83.)

The key to this mystery was furnished by the accidental perusal of the
famous essay of Malthus "On Population" in the autumn of 1838. The
necessary result of unrestricted multiplication is competition for the
means of existence. The success of one competitor involves the failure of
the rest, that is, their extinction; and this "selection" is dependent on
the better adaptation of the successful competitor to the conditions of the
competition. Variation occurs under natural, no less than under artificial,
conditions. Unrestricted multiplication implies the competition of
varieties and the selection of those which are relatively best adapted to
the conditions.

Neither Erasmus Darwin, nor Lamarck, had any inkling of the possibility of
this process of "natural selection"; and though it had been foreshadowed by
Wells in 1813, and more fully stated by Matthew in 1831, the speculations
of the latter writer remained unknown to naturalists until after the
publication of the "Origin of Species."

Darwin found in the doctrine of the selection of favourable variations by
natural causes, which thus presented itself to his mind, not merely a
probable theory of the origin of the diverse species of living forms, but
that explanation of the phenomena of adaptation, which previous
speculations had utterly failed to give. The process of natural selection
is, in fact, dependent on adaptation--it is all one, whether one says that
the competitor which survives is the "fittest" or the "best adapted." And
it was a perfectly fair deduction that even the most complicated
adaptations might result from the summation of a long series of simple
favourable variations.

Darwin notes as a serious defect in the first sketch of his theory that he
had omitted to consider one very important problem, the solution of which
did not occur to him till some time afterwards. "This problem is the
tendency in organic beings descended from the same stock to diverge in
character as they become modified.... The solution, as I believe, is that
the modified offspring of all dominant and increasing forms tend to become
adapted to many and highly diversified places in the economy of nature."
(I. p. 84.)

It is curious that so much importance should be attached to this
supplementary idea. It seems obvious that the theory of the origin of
species by natural selection necessarily involves the divergence of the
forms selected. An individual which varies, _ipso facto_ diverges from
the type of its species; and its progeny, in which the variation becomes
intensified by selection, must diverge still more, not only from the parent
stock, but from any other race of that stock starting from, a variation of
a different character. The selective process could not take place unless
the selected variety was either better adapted to the conditions than the
original stock, or adapted to other conditions than the original stock. In
the first case, the original stock would be sooner or later extirpated; in
the second, the type, as represented by the original stock and the variety,
would occupy more diversified stations than it did before.

The theory, essentially such as it was published fourteen years later, was
written out in 1844, and Darwin was so fully convinced of the importance of
his work, as it then stood, that he made special arrangements for its
publication in case of his death. But it is a singular example of reticent
fortitude, that, although for the next fourteen years the subject never
left his mind, and during the latter half of that period he was constantly
engaged in amassing facts bearing upon it from wide reading, a colossal
correspondence, and a long series of experiments, only two or three friends
were cognisant of his views. To the outside world he seemed to have his
hands quite sufficiently full of other matters. In 1844, he published his
observations on the volcanic islands visited during the voyage of the
"Beagle." In 1845, a largely remodelled edition of his "Journal" made its
appearance, and immediately won, as it has ever since held, the favour of
both the scientific and the unscientific public. In 1846, the "Geological
Observations in South America" came out, and this book was no sooner
finished than Darwin set to work upon the Cirripedes. He was led to
undertake this long and heavy task, partly by his desire to make out the
relations of a very anomalous form which he had discovered on the coast of
Chili; and partly by a sense of "presumption in accumulating facts and
speculating on the subject of variation without having worked out my due
share of species." (II. p. 31.) The eight or nine years of labour, which
resulted in a monograph of first-rate importance in systematic zoology (to
say nothing of such novel points as the discovery of complemental males),
left Darwin no room to reproach himself on this score, and few will share
his "doubt whether the work was worth the consumption of so much time." (I.
p. 82.)

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