Darwiniana
by
Thomas Henry Huxley

Part 4 out of 6



probable source for that inability to refrain from forming an hypothesis on
every subject which he confesses to be one of the leading characteristics
of his own mind, some pages further on (I., p. 103). Dr. R. W. Darwin,
again, was the third son of Erasmus Darwin, also a physician of great
repute, who shared the intimacy of Watt and Priestley, and was widely known
as the author of "Zoonomia," and other voluminous poetical and prose works
which had a great vogue in the latter half of the eighteenth century. The
celebrity which they enjoyed was in part due to the attractive style (at
least according to the taste of that day) in which the author's extensive,
though not very profound, acquaintance with natural phenomena was set
forth; but in a still greater degree, probably, to the boldness of the
speculative views, always ingenious and sometimes fantastic, in which he
indulged. The conception of evolution set afoot by De Maillet and others,
in the early part of the century, not only found a vigorous champion in
Erasmus Darwin, but he propounded an hypothesis as to the manner in which
the species of animals and plants have acquired their characters, which is
identical in principle with that subsequently rendered famous by Lamarck.

That Charles Darwin's chief intellectual inheritance came to him from the
paternal side, then, is hardly doubtful. But there is nothing to show that
he was, to any sensible extent, directly influenced by his grandfather's
biological work. He tells us that a perusal of the "Zoonomia" in early life
produced no effect upon him, although he greatly admired it; and that, on
reading it again, ten or fifteen years afterwards, he was much
disappointed, "the proportion of speculation being so large to the facts
given." But with his usual anxious candour he adds, "Nevertheless, it is
probable that the hearing, rather early in life, such views maintained and
praised, may have favoured my upholding them, in a different form, in my
'Origin of Species.'" (I., p. 38.) Erasmus Darwin was in fact an
anticipator of Lamarck, and not of Charles Darwin; there is no trace in his
works of the conceptions by the addition of which his grandson
metamorphosed the theory of evolution as applied to living things and gave
it a new foundation.

Charles Darwin's childhood and youth afforded no intimation that he would
he, or do, anything out of the common run. In fact, the prognostications of
the educational authorities into whose hands he first fell were most
distinctly unfavourable; and they counted the only boy of original genius
who is known to have come under their hands as no better than a dunce. The
history of the educational experiments to which Darwin was subjected is
curious, and not without a moral for the present generation. There were
four of them, and three were failures. Yet it cannot be said that the
materials on which the pedagogic powers operated were other than good. In
his boyhood Darwin was strong, well-grown, and active, taking the keen
delight in field sports and in every description of hard physical exercise
which is natural to an English country-bred lad; and, in respect of things
of the mind, he was neither apathetic, nor idle, nor one-sided. The
"Autobiography" tells us that he "had much zeal for whatever interested"
him, and he was interested in many and very diverse topics. He could work
hard, and liked a complex subject better than an easy one. The "clear
geometrical proofs" of Euclid delighted him. His interest in practical
chemistry, carried out in an extemporised laboratory, in which he was
permitted to assist by his elder brother, kept him late at work, and earned
him the nickname of "gas" among his schoolfellows. And there could have
been no insensibility to literature in one who, as a boy, could sit for
hours reading Shakespeare, Milton, Scott, and Byron; who greatly admired
some of the Odes of Horace; and who, in later years, on board the "Beagle,"
when only one book could be carried on an expedition, chose a volume of
Milton for his companion.

Industry, intellectual interests, the capacity for taking pleasure in
deductive reasoning, in observation, in experiment, no less than in the
highest works of imagination: where these qualities are present any
rational system of education should surely be able to make something of
them. Unfortunately for Darwin, the Shrewsbury Grammar School, though good
of its kind, was an institution of a type universally prevalent in this
country half a century ago, and by no means extinct at the present day. The
education given was "strictly classical," "especial attention" being "paid
to verse-making," while all other subjects, except a little ancient
geography and history, were ignored. Whether, as in some famous English
schools at that date and much later, elementary arithmetic was also left
out of sight does not appear; but the instruction in Euclid which gave
Charles Darwin so much satisfaction was certainly supplied by a private
tutor. That a boy, even in his leisure hours, should permit himself to be
interested in any but book-learning seems to have been regarded as little
better than an outrage by the head master, who thought it his duty to
administer a public rebuke to young Darwin for wasting his time on such a
contemptible subject as chemistry. English composition and literature,
modern languages, modern history, modern geography, appear to have been
considered to be as despicable as chemistry.

For seven long years Darwin got through his appointed tasks; construed
without cribs, learned by rote whatever was demanded, and concocted his
verses in approved schoolboy fashion. And the result, as it appeared to his
mature judgment, was simply negative. "The school as a means of education
to me was simply a blank." (I. p. 32.) On the other hand, the extraneous
chemical exercises, which the head master treated so contumeliously, are
gratefully spoken of as the "best part" of his education while at school.
Such is the judgment of the scholar on the school; as might be expected, it
has its counterpart in the judgment of the school on the scholar. The
collective intelligence of the staff of Shrewsbury School could find
nothing but dull mediocrity in Charles Darwin. The mind that found
satisfaction in knowledge, but very little in mere learning; that could
appreciate literature, but had no particular aptitude for grammatical
exercises; appeared to the "strictly classical" pedagogue to be no mind at
all. As a matter of fact, Darwin's school education left him ignorant of
almost all the things which it would have been well for him to know, and
untrained in all the things it would have been useful for him to be able to
do, in after life. Drawing, practice in English composition, and
instruction in the elements of the physical sciences, would not only have
been infinitely valuable to him in reference to his future career, but
would have furnished the discipline suited to his faculties, whatever that
career might be. And a knowledge of French and German, especially the
latter, would have removed from his path obstacles which he never fully
overcame.

Thus, starved and stunted on the intellectual side, it is not surprising
that Charles Darwin's energies were directed towards athletic amusements
and sport, to such an extent, that even his kind and sagacious father could
be exasperated into telling him that "he cared for nothing but shooting,
dogs, and rat-catching." (I. p. 32.) It would be unfair to expect even the
wisest of fathers to have foreseen that the shooting and the rat-catching,
as training in the ways of quick observation and in physical endurance,
would prove more valuable than the construing and verse-making to his son,
whose attempt, at a later period of his Life, to persuade himself "that
shooting was almost an intellectual employment: it required so much skill
to judge where to find most game, and to hunt the dogs well" (I. p. 43),
was by no means so sophistical as he seems to have been ready to admit.

In 1825, Dr. Darwin came to the very just conclusion that his son Charles
would do no good by remaining at Shrewsbury School, and sent him to join
his elder brother Erasmus, who was studying medicine at Edinburgh, with the
intention that the younger son should also become a medical practitioner.
Both sons, however, were well aware that their inheritance would relieve
them from the urgency of the struggle for existence which most professional
men have to face; and they seemed to have allowed their tastes, rather than
the medical curriculum, to have guided their studies. Erasmus Darwin was
debarred by constant ill-health from seeking the public distinction which
his high intelligence and extensive knowledge would, under ordinary
circumstances, have insured. He took no great interest in biological
subjects, but his companionship must have had its influence on his brother.
Still more was exerted by friends like Coldstream and Grant, both
subsequently well-known zoologists (and the latter an enthusiastic
Lamarckian), by whom Darwin was induced to interest himself in marine
zoology. A notice of the ciliated germs of _Flustra_, communicated to
the Plinian Society in 1826, was the first fruits of Darwin's half century
of scientific work. Occasional attendance at the Wernerian Society brought
him into relation with that excellent ornithologist the elder Macgillivray,
and enabled him to see and hear Audubon. Moreover, he got lessons in
bird-stuffing from a negro, who had accompanied the eccentric traveller
Waterton in his wanderings, before settling in Edinburgh.

No doubt Darwin picked up a great deal of valuable knowledge during his two
years' residence in Scotland; but it is equally clear that next to none of
it came through the regular channels of academic education. Indeed, the
influence of the Edinburgh professoriate appears to have been mainly
negative, and in some cases deterrent; creating in his mind, not only a
very low estimate of the value of lectures, but an antipathy to the
subjects which had been the occasion of the boredom inflicted upon him by
their instrumentality. With the exception of Hope, the Professor of
Chemistry, Darwin found them all "intolerably dull." Forty years afterwards
he writes of the lectures of the Professor of Materia Medica that they were
"fearful to remember." The Professor of Anatomy made his lectures "as dull
as he was himself," and he must have been very dull to have wrung from his
victim the sharpest personal remark recorded as his. But the climax seems
to have been attained by the Professor of Geology and Zoology, whose
prælections were so "incredibly dull" that they produced in their hearer
the somewhat rash determination never "to read a book on geology or in any
way to study the science" so long as he lived. (I. p. 41.)

There is much reason to believe that the lectures in question were
eminently qualified to produce the impression which they made; and there
can be little doubt, that Darwin's conclusion that his time was better
employed in reading than in listening to such lectures was a sound one. But
it was particularly unfortunate that the personal and professorial dulness
of the Professor of Anatomy, combined with Darwin's sensitiveness to the
disagreeable concomitants of anatomical work, drove him away from the
dissecting room. In after life, he justly recognised that this was an
"irremediable evil" in reference to the pursuits he eventually adopted;
indeed, it is marvellous that he succeeded in making up for his lack of
anatomical discipline, so far as his work on the Cirripedes shows he did.
And the neglect of anatomy had the further unfortunate result that it
excluded him from the best opportunity of bringing himself into direct
contact with the facts of nature which the University had to offer. In
those days, almost the only practical scientific work accessible to
students was anatomical, and the only laboratory at their disposal the
dissecting room.

We may now console ourselves with the reflection that the partial evil was
the general good. Darwin had already shown an aptitude for practical
medicine (I. p. 37); and his subsequent career proved that he had the
making of an excellent anatomist. Thus, though his horror of operations
would probably have shut him off from surgery, there was nothing to prevent
him (any more than the same peculiarity prevented his father) from passing
successfully through the medical curriculum and becoming, like his father
and grandfather, a successful physician, in which case "The Origin of
Species" would not have been written. Darwin has jestingly alluded to the
fact that the shape of his nose (to which Captain Fitzroy objected), nearly
prevented his embarkation in the "Beagle"; it may be that the sensitiveness
of that organ secured him for science.

At the end of two years' residence in Edinburgh it hardly needed Dr.
Darwin's sagacity to conclude that a young man, who found nothing but
dulness in professorial lucubrations, could not bring himself to endure a
dissecting room, fled from operations, and did not need a profession as a
means of livelihood, was hardly likely to distinguish himself as a student
of medicine. He therefore made a new suggestion, proposing that his son
should enter an English University and qualify for the ministry of the
Church. Charles Darwin found the proposal agreeable, none the less,
probably, that a good deal of natural history and a little shooting were by
no means held, at that time, to be incompatible with the conscientious
performance of the duties of a country clergyman. But it is characteristic
of the man, that he asked time for consideration, in order that he might
satisfy himself that he could sign the Thirty-nine Articles with a clear
conscience. However, the study of "Pearson on the Creeds" and a few other
books of divinity soon assured him that his religious opinions left nothing
to be desired on the score of orthodoxy, and he acceded to his father's
proposition.

The English University selected was Cambridge; but an unexpected obstacle
arose from the fact that, within the two years which had elapsed, since the
young man who had enjoyed seven years of the benefit of a strictly
classical education had left school, he had forgotten almost everything he
had learned there, "even to some few of the Greek letters." (I. p. 46.)
Three months with a tutor, however, brought him back to the point of
translating Homer and the Greek Testament "with moderate facility," and
Charles Darwin commenced the third educational experiment of which he was
the subject, and was entered on the books of Christ's College in October
1827. So far as the direct results of the academic training thus received
are concerned, the English University was not more successful than the
Scottish. "During the three years which I spent at Cambridge my time was
wasted, as far as the academical studies were concerned, as completely as
at Edinburgh and as at school." (I. p. 46.) And yet, as before, there is
ample evidence that this negative result cannot be put down to any native
defect on the part of the scholar. Idle and dull young men, or even young
men who being neither idle nor dull, are incapable of caring for anything
but some hobby, do not devote themselves to the thorough study of Paley's
"Moral Philosophy," and "Evidences of Christianity"; nor are their
reminiscences of this particular portion of their studies expressed in
terms such as the following: "The logic of this book [the 'Evidences'] and,
as I may add, of his 'Natural Theology' gave me as much delight as did
Euclid." (I. p. 47.)

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.)

In science no man can safely speculate about the nature and relation of
things with which he is unacquainted at first hand, and the acquirement of
an intimate and practical knowledge of the process of species-making and of
all the uncertainties which underlie the boundaries between species and
varieties, drawn by even the most careful and conscientious systematists
[Footnote: "After describing a set of forms as distinct species, tearing up
my MS., and making them one species, tearing that up and making them
separate, and then making them one again (which has happened to me), I have
gnashed my teeth, cursed species, and asked what sin I had committed to be
so punished." (II. p. 40.) Is there any naturalist provided with a logical
sense and a large suite of specimens, who has not undergone pangs of the
sort described in this vigorous paragraph, which might, with advantage, be
printed on the title-page of every systematic monograph as a warning to the
uninitiated?] were of no less importance to the author of the "Origin of
Species" than was the bearing of the Cirripede work upon "the principles of
a natural classification." (I. p. 81.) No one, as Darwin justly observes,
has a "right to examine the question of species who has not minutely
described many." (II. p. 39.)

In September, 1854, the Cirripede work was finished, "ten thousand
barnacles" had been sent "out of the house, all over the world," and Darwin
had the satisfaction of being free to turn again to his "old notes on
species." In 1855, he began to breed pigeons, and to make observations on
the effects of use and disuse, experiments on seeds, and so on, while
resuming his industrious collection of facts, with a view "to see how far
they favour or are opposed to the notion that wild species are mutable or
immutable. I mean with my utmost power to give all arguments and facts on
both sides. I have a _number_ of people helping me every way, and
giving me most valuable assistance; but I often doubt whether the subject
will not quite overpower me." (II. p. 49.)

Early in 1856, on Lyell's advice, Darwin began to write out his views on
the origin of species on a scale three or four times as extensive as that
of the work published in 1859. In July of the same year he gave a brief
sketch of his theory in a letter to Asa Gray; and, in the year 1857, his
letters to his correspondents show him to be busily engaged on what he
calls his "big book." (II. pp. 85, 94.) In May, 1857, Darwin writes to
Wallace: "I am now preparing my work [on the question how and in what way
do species and varieties differ from each other] for publication, but I
find the subject so very large, that, though I have written many chapters,
I do not suppose I shall go to press for two years." (II. p. 95.) In
December, 1857, he writes, in the course of a long letter to the same
correspondent, "I am extremely glad to hear that you are attending to
distribution in accordance with theoretical ideas. I am a firm believer
that without speculation there is no good and original observation." (II.
p. 108.) [Footnote: The last remark contains a pregnant truth, but it must
be confessed it hardly squares with the declaration in the
_Autobiography_, (I. p. 83), that he worked on "true Baconian
principles."] In June, 1858, he received from Mr. Wallace, then in the
Malay Archipelago, an "Essay on the tendency of varieties to depart
indefinitely from the original type," of which Darwin says, "If Wallace had
my MS. sketch written out in 1842 he could not have made a better short
abstract! Even his terms stand now as heads of my chapters. Please return
me the MS., which he does not say he wishes me to publish, but I shall, of
course, at once write and offer to send it to any journal. So all my
originality, whatever it may amount to, will be smashed, though my book, if
ever it will have any value, will not be deteriorated; as all the labour
consists in the application of the theory." (II. p. 116.)

Thus, Darwin's first impulse was to publish Wallace's essay without note or
comment of his own. But, on consultation with Lyell and Hooker, the latter
of whom had read the sketch of 1844, they suggested, as an undoubtedly more
equitable course, that extracts from the MS. of 1844 and from the letter to
Dr. Asa Gray should be communicated to the Linnean Society along with
Wallace's essay. The joint communication was read on July 1, 1858, and
published under the title "On the Tendency of Species to form Varieties;
and on the Perpetuation of Varieties and Species by Natural Means of
Selection." This was followed, on Darwin's part, by the composition of a
summary account of the conclusions to which his twenty years' work on the
species question had led him. It occupied him for thirteen months, and
appeared in November, 1859, under the title "On the Origin of Species by
means of Natural Selection or the Preservation of Favoured Races in the
Struggle of Life."

It is doubtful if any single book, except the "Principia," ever worked so
great and so rapid a revolution in science, or made so deep an impression
on the general mind. It aroused a tempest of opposition and met with
equally vehement support, and it must be added that no book has been more
widely and persistently misunderstood by both friends and foes. In 1861,
Darwin remarks to a correspondent, "You understand my book perfectly, and
that I find a very rare event with my critics." (I. p. 313.) The immense
popularity which the "Origin" at once acquired was no doubt largely due to
its many points of contact with philosophical and theological questions in
which every intelligent man feels a profound interest; but a good deal must
be assigned to a somewhat delusive simplicity of style, which tends to
disguise the complexity and difficulty of the subject, and much to the
wealth of information on all sorts of curious problems of natural history,
which is made accessible to the most unlearned reader. But long occupation
with the work has led the present writer to believe that the "Origin of
Species" is one of the hardest of books to master; [Footnote: He is
comforted to find that probably the best qualified judge among all the
readers of the _Origin_ in 1859 was of the same opinion. Sir J. Hooker
writes, "It is the very hardest book to read, to full profit, that I ever
tried." (II. p. 242.)] and he is justified in this conviction by observing
that although the "Origin" has been close on thirty years before the world,
the strangest misconceptions of the essential nature of the theory therein
advocated are still put forth by serious writers.

Although, then, the present occasion is not suitable for any detailed
criticism of the theory, or of the objections which have been brought
against it, it may not be out of place to endeavour to separate the
substance of the theory from its accidents; and to show that a variety not
only of hostile comments, but of friendly would-be improvements lose their
_raison d'être_ to the careful student. Observation proves the
existence among all living beings of phenomena of three kinds, denoted by
the terms heredity, variation, and multiplication. Progeny tend to resemble
their parents; nevertheless all their organs and functions are susceptible
of departing more or less from the average parental character; and their
number is in excess of that of their parents. Severe competition for the
means of living, or the struggle for existence, is a necessary consequence
of unlimited multiplication; while selection, or the preservation of
favourable variations and the extinction of others, is a necessary
consequence of severe competition. "Favourable variations" are those which
are better adapted to surrounding conditions. It follows, therefore, that
every variety which is selected into a species is so favoured and preserved
in consequence of being, in some one or more respects, better adapted to
its surroundings than its rivals. In other words, every species which
exists, exists in virtue of adaptation, and whatever accounts for that
adaptation accounts for the existence of the species.

To say that Darwin has put forward a theory of the adaptation of species,
but not of their origin, is therefore to misunderstand the first principles
of the theory. For, as has been pointed out, it is a necessary consequence
of the theory of selection that every species must have some one or more
structural or functional peculiarities, in virtue of the advantage
conferred by which, it has fought through the crowd of its competitors and
achieved a certain duration. In this sense, it is true that every species
has been "originated" by selection.

There is another sense, however, in which it is equally true that selection
originates nothing. "Unless profitable variations ... occur natural
selection can do nothing" ("Origin," Ed. I. p. 82). "Nothing can be
effected unless favourable variations occur" (_ibid_., p. 108). "What
applies to one animal will apply throughout time to all animals--that is,
if they vary--for otherwise natural selection can do nothing. So it will be
with plants" (_ibid_., p. 113). Strictly speaking, therefore, the
origin of species in general lies in variation; while the origin of any
particular species lies, firstly, in the occurrence, and secondly, in the
selection and preservation of a particular variation. Clearness on this
head will relieve one from the necessity of attending to the fallacious
assertion that natural selection is a _deus ex machinâ_, or occult
agency.

Those, again, who confuse the operation of the natural causes which bring
about variation and selection with what they are pleased to call "chance"
can hardly have read the opening paragraph of the fifth chapter of the
"Origin" (Ed. I, p. 131): "I have sometimes spoken as if the variations ...
had been due to chance. This is of course a wholly incorrect expression,
but it seems to acknowledge plainly our ignorance of the cause of each
particular variation."

Another point of great importance to the right comprehension of the theory,
is, that while every species must needs have some adaptive advantageous
characters to which it owes its preservation by selection, it may possess
any number of others which are neither advantageous nor disadvantageous,
but indifferent, or even slightly disadvantageous. (_Ibid_., p. 81.)
For variations take place, not merely in one organ or function at a time,
but in many; and thus an advantageous variation, which gives rise to the
selection of a new race or species, may be accompanied by others which are
indifferent, but which are just as strongly hereditary as the advantageous
variations. The advantageous structure is but one product of a modified
general constitution which may manifest itself by several other products;
and the selective process carries the general constitution along with the
advantageous special peculiarity. A given species of plant may owe its
existence to the selective adaptation of its flowers to insect fertilisers;
but the character of its leaves may be the result of variations of an
indifferent character. It is the origin of variations of this kind to which
Darwin refers in his frequent reference to what he calls "laws of
correlation of growth" or "correlated variation."

These considerations lead us further to see the inappropriateness of the
objections raised to Darwin's theory on the ground that natural selection
does not account for the first commencements of useful organs. But it does
not pretend to do so. The source of such commencements is necessarily to be
sought in different variations, which remain unaffected by selection until
they have taken such a form as to become utilisable in the struggle for
existence.

It is not essential to Darwin's theory that anything more should be assumed
than the facts of heredity, variation, and unlimited multiplication; and
the validity of the deductive reasoning as to the effect of the last (that
is, of the struggle for existence which it involves) upon the varieties
resulting from the operation of the former. Nor is it essential that one
should take up any particular position in regard to the mode of variation,
whether, for example, it takes place _per saltum_ or gradually;
whether it is definite in character or indefinite. Still less are those who
accept the theory bound to any particular views as to the causes of
heredity or of variation.

That Darwin held strong opinions on some or all of these points may be
quite true; but, so far as the theory is concerned, they must be regarded
as _obiter dicta_. With respect to the causes of variation, Darwin's
opinions are, from first to last, put forward altogether tentatively. In
the first edition of the "Origin," he attributes the strongest influence to
changes in the conditions of life of parental organisms, which he appears
to think act on the germ through the intermediation of the sexual organs.
He points out, over and over again, that habit, use, disuse, and the direct
influence of conditions have some effect, but he does not think it great,
and he draws attention to the difficulty of distinguishing between effects
of these agencies and those of selection. There is, however, one class of
variations which he withdraws from the direct influence of selection,
namely, the variations in the fertility of the sexual union of more or less
closely allied forms. He regards less fertility, or more or less complete
sterility, as "incidental to other acquired differences." (_Ibid_., p.
245.)

Considering the difficulties which surround the question of the causes of
variation, it is not to be wondered at, that Darwin should have inclined,
sometimes, rather more to one and, sometimes, rather more to another of the
possible alternatives. There is little difference between the last edition
of the "Origin" (1872) and the first on this head. In 1876, however, he
writes to Moritz Wagner, "In my opinion, the greatest error which I have
committed has been not allowing sufficient weight to the direct action of
the environments, i.e., food, climate, &c., independently of natural
selection. ...When I wrote the 'Origin,' and for some years afterwards, I
could find little good evidence of the direct action of the environment;
now there is a large body of evidence, and your case of the Saturnia is one
of the most remarkable of which I have heard." (III, p. 159.) But there is
really nothing to prevent the most tenacious adherent to the theory of
natural selection from taking any view he pleases as to the importance of
the direct influence of conditions and the hereditary transmissibility of
the modifications which they produce. In fact, there is a good deal to be
said for the view that the so-called direct influence of conditions is
itself a case of selection. Whether the hypothesis of Pangenesis be
accepted or rejected, it can hardly be doubted that the struggle for
existence goes on not merely between distinct organisms, but between the
physiological units of which each organism is composed, and that changes in
external conditions favour some and hinder others.

After a short stay in Cambridge, Darwin resided in London for the first
five years which followed his return to England; and for three years, he
held the post of Secretary to the Geological Society, though he shared to
the full his friend Lyell's objection to entanglement in such engagements.
In fact, he used to say in later life, more than half in earnest, that he
gave up hoping for work from men who accepted official duties and,
especially, Government appointments. Happily for him, he was exempted from
the necessity of making any sacrifice of this kind, but an even heavier
burden was laid upon him. During the earlier half of his voyage Darwin
retained the vigorous health of his boyhood, and indeed proved himself to
be exceptionally capable of enduring fatigue and privation. An anomalous
but severe disorder, which laid him up for several weeks at Valparaiso in
1834, however, seems to have left its mark on his constitution; and, in the
later years of his London life, attacks of illness, usually accompanied by
severe vomiting and great prostration of strength, became frequent. As he
grew older, a considerable part of every day, even at his best times, was
spent in misery; while, not unfrequently, months of suffering rendered work
of any kind impossible. Even Darwin's remarkable tenacity of purpose and
methodical utilisation of every particle of available energy could not have
enabled him to achieve a fraction of the vast amount of labour he got
through, in the course of the following forty years, had not the wisest and
the most loving care unceasingly surrounded him from the time of his
marriage in 1839. As early as 1842, the failure of health was so marked
that removal from London became imperatively necessary; and Darwin
purchased a house and grounds at Down, a solitary hamlet in Kent, which was
his home for the rest of his life. Under the strictly regulated conditions
of a valetudinarian existence, the intellectual activity of the invalid
might have put to shame most healthy men; and, so long as he could hold his
head up, there was no limit to the genial kindness of thought and action
for all about him. Those friends who were privileged to share the intimate
life of the household at Down have an abiding memory of the cheerful
restfulness which pervaded and characterised it.

After mentioning his settlement at Down, Darwin writes in his
Autobiography:--

"My chief enjoyment and sole employment throughout life has been scientific
work; and the excitement from such work makes me, for the time, forget, or
drives quite away, my daily discomfort. I have, therefore, nothing to
record during the rest of my life, except the publication of my several
books." (I, p. 79.)

Of such works published subsequently to 1859, several are monographic
discussions of topics briefly dealt with in the "Origin," which, it must
always be recollected, was considered by the author to be merely an
abstract of an _opus majus_.

The earliest of the books which may be placed in this category, "On the
Various Contrivances by which Orchids are Fertilised by Insects," was
published in 1862, and whether we regard its theoretical significance, the
excellence of the observations and the ingenuity of the reasonings which it
records, or the prodigious mass of subsequent investigation of which it has
been the parent, it has no superior in point of importance. The conviction
that no theory of the origin of species could be satisfactory which failed
to offer an explanation of the way in which mechanisms involving
adaptations of structure and function to the performance of certain
operations are brought about, was, from the first, dominant in Darwin's
mind. As has been seen, he rejected Lamarck's views because of their
obvious incapacity to furnish such an explanation in the case of the great
majority of animal mechanisms, and in that of all those presented by the
vegetable world.

So far back as 1793, the wonderful work of Sprengel had established, beyond
any reasonable doubt, the fact that, in a large number of cases, a flower
is a piece of mechanism the object of which is to convert insect visitors
into agents of fertilisation. Sprengel's observations had been most
undeservedly neglected and well-nigh forgotten; but Robert Brown having
directed Darwin's attention to them in 1841, he was attracted towards the
subject, and verified many of Sprengel's statements. (III, p. 258.) It may
be doubted whether there was a living botanical specialist, except perhaps
Brown, who had done as much. If, however, adaptations of this kind were to
be explained by natural selection, it was necessary to show that the plants
which were provided with mechanisms for ensuring the aid of insects as
fertilisers, were by so much the better fitted to compete with their
rivals. This Sprengel had not done. Darwin had been attending to cross
fertilisation in plants so far back as 1839, from having arrived, in the
course of his speculations on the origin of species, at the conviction
"that crossing played an important part in keeping specific forms constant"
(I, p. 90). The further development of his views on the importance of cross
fertilisation appears to have taken place between this time and 1857, when
he published his first papers on the fertilisation of flowers in the
"Gardener's Chronicle." If the conclusion at which he ultimately arrived,
that cross fertilisation is favourable to the fertility of the parent and
to the vigour of the offspring, is correct, then it follows that all those
mechanisms which hinder self-fertilisation and favour crossing must be
advantageous in the struggle for existence; and, the more perfect the
action of the mechanism, the greater the advantage. Thus the way lay open
for the operation of natural selection in gradually perfecting the flower
as a fertilisation-trap. Analogous reasoning applies to the fertilising
insect. The better its structure is adapted to that of the trap, the more
will it be able to profit by the bait, whether of honey or of pollen, to
the exclusion of its competitors. Thus, by a sort of action and reaction, a
two-fold series of adaptive modifications will be brought about.

In 1865, the important bearing of this subject on his theory led Darwin to
commence a great series of laborious and difficult experiments on the
fertilisation of plants, which occupied him for eleven years, and furnished
him with the unexpectedly strong evidence in favour of the influence of
crossing which he published in 1876, under the title of "The Effects of
Cross and Self Fertilisation in the Vegetable Kingdom." Incidentally, as it
were, to this heavy piece of work, he made the remarkable series of
observations on the different arrangements by which crossing is favoured
and, in many cases, necessitated, which appeared in the work on "The
Different Forms of Flowers in Plants of the same Species" in 1877.

In the course of the twenty years during which Darwin was thus occupied in
opening up new regions of investigation to the botanist and showing the
profound physiological significance of the apparently meaningless
diversities of floral structure, his attention was keenly alive to any
other interesting phenomena of plant life which came in his way. In his
correspondence, he not unfrequently laughs at himself for his ignorance of
systematic botany; and his acquaintance with vegetable anatomy and
physiology was of the slenderest. Nevertheless, if any of the less common
features of plant life came under his notice, that imperious necessity of
seeking for causes which nature had laid upon him, impelled, and indeed
compelled, him to inquire the how and the why of the fact, and its bearing
on his general views. And as, happily, the atavic tendency to frame
hypotheses was accompanied by an equally strong need to test them by
well-devised experiments, and to acquire all possible information before
publishing his results, the effect was that he touched no topic without
elucidating it.

Thus the investigation of the operations of insectivorous plants, embodied
in the work on that topic published in 1875, was started fifteen years
before, by a passing observation made during one of Darwin's rare holidays.

"In the summer of 1860, I was idling and resting near Hartfield, where two
species of Drosera abound; and I noticed that numerous insects had been
entrapped by the leaves. I carried home some plants, and on giving them
some insects saw the movements of the tentacles, and this made me think it
possible that the insects were caught for some special purpose.
Fortunately, a crucial test occurred to me, that of placing a large number
of leaves in various nitrogenous and non-nitrogenous fluids of equal
density; and as soon as I found that the former alone excited energetic
movements, it was obvious that here was a fine new field for
investigation." (I, p. 95.)

The researches thus initiated led to the proof that plants are capable of
secreting a digestive fluid like that of animals, and of profiting by the
result of digestion; whereby the peculiar apparatuses of the insectivorous
plants were brought within the scope of natural selection. Moreover, these
inquiries widely enlarged our knowledge of the manner in which stimuli are
transmitted in plants, and opened up a prospect of drawing closer the
analogies between the motor processes of plants and those of animals.

So with respect to the books on "Climbing Plants" (1875), and on the "Power
of Movement in Plants" (1880), Darwin says;--

"I was led to take up this subject by reading a short paper by Asa Gray,
published in 1858. He sent me some seeds, and on raising some plants I was
so much fascinated and perplexed by the revolving movements of the tendrils
and stems, which movements are really very simple, though appearing at
first sight very complex, that I procured various other kinds of climbing
plants and studied the whole subject.... Some of the adaptations displayed
by climbing plants are as beautiful as those of orchids for ensuring
cross-fertilisation." (I, p. 93.)

In the midst of all this amount of work, remarkable alike for its variety
and its importance, among plants, the animal kingdom was by no means
neglected. A large moiety of "The Variation of Animals and Plants under
Domestication" (1868), which contains the _pièces justificatives_ of
the first chapter of the "Origin," is devoted to domestic animals, and the
hypothesis of "pangenesis" propounded in the second volume applies to the
whole living world. In the "Origin" Darwin throws out some suggestions as
to the causes of variation, but he takes heredity, as it is manifested by
individual organisms, for granted, as an ultimate fact; pangenesis is an
attempt to account for the phenomena of heredity in the organism, on the
assumption that the physiological units of which the organism is composed
give off gemmules, which, in virtue of heredity, tend to reproduce the unit
from which they are derived.

That Darwin had the application of his theory to the origin of the human
species clearly in his mind in 1859, is obvious from a passage in the first
edition of "The Origin of Species." (Ed. I, p. 488.) "In the distant future
I see open fields for far more important researches. Psychology will be
based on a new foundation, that of the necessary acquirement of each mental
power and capacity by gradation. Light will be thrown on the origin of man
and his history." It is one of the curiosities of scientific literature,
that, in the face of this plain declaration, its author should have been
charged with concealing his opinions on the subject of the origin of man.
But he reserved the full statement of his views until 1871, when the
"Descent of Man" was published. The "Expression of the Emotions"
(originally intended to form only a chapter in the "Descent of Man") grew
into a separate volume, which appeared in 1872. Although always taking a
keen interest in geology, Darwin naturally found no time disposable for
geological work, even had his health permitted it, after he became
seriously engaged with the great problem of species. But the last of his
labours is, in some sense, a return to his earliest, inasmuch as it is an
expansion of a short paper read before the Geological Society more than
forty years before, and, as he says, "revived old geological thoughts" (I,
p. 98). In fact, "The Formation of Vegetable Mould through the Action of
Worms," affords as striking an example of the great results produced by the
long-continued operation of small causes as even the author of the
"Principles of Geology" could have desired.

In the early months of 1882 Darwin's health underwent a change for the
worse; attacks of giddiness and fainting supervened, and on the 19th of
April he died. On the 24th, his remains were interred in Westminster Abbey,
in accordance with the general feeling that such a man as he should not go
to the grave without some public recognition of the greatness of his work.

Mr. Darwin became a Fellow of the Royal Society in 1839; one of the Royal
Medals was awarded to him in 1853, and he received the Copley Medal in
1864. The "Life and Letters," edited with admirable skill and judgment by
Mr. Francis Darwin, gives a full and singularly vivid presentment of his
father's personal character, of his mode of work, and of the events of his
life. In the present brief obituary notice, the writer has attempted
nothing more than to select and put together those facts which enable us to
trace the intellectual evolution of one of the greatest of the many great
men of science whose names adorn the long roll of the Fellows of the Royal
Society.




XI

ON OUR KNOWLEDGE OF THE CAUSES OF THE PHENOMENA OF ORGANIC NATURE

[_Six Lectures to Working Men_.--1863.]



I. THE PRESENT CONDITION OF ORGANIC NATURE


When it was my duty to consider what subject I would select for the six
lectures which I shall now have the pleasure of delivering to you, it
occurred to me that I could not do better than endeavour to put before you
in a true light, or in what I might perhaps with more modesty call, that
which I conceive myself to be the true light, the position of a book which
has been more praised and more abused, perhaps, than any book which has
appeared for some years;--I mean Mr. Darwin's work on the "Origin of
Species." That work, I doubt not, many of you have read; for I know the
inquiring spirit which is rife among you. At any rate, all of you will have
heard of it,--some by one kind of report and some by another kind of
report; the attention of all and the curiosity of all have been probably
more or less excited on the subject of that work. All I can do, and all I
shall attempt to do, is to put before you that kind of judgment which has
been formed by a man, who, of course, is liable to judge erroneously; but,
at any rate, of one whose business and profession it is to form judgments
upon questions of this nature.

And here, as it will always happen when dealing with an extensive subject,
the greater part of my course--if, indeed, so small a number of lectures
can be properly called a course--must be devoted to preliminary matters, or
rather to a statement of those facts and of those principles which the work
itself dwells upon, and brings more or less directly before us. I have no
right to suppose that all or any of you are naturalists; and, even if you
were, the misconceptions and misunderstandings prevalent even among
naturalists, on these matters, would make it desirable that I should take
the course I now propose to take,--that I should start from the
beginning,--that I should endeavour to point out what is the existing state
of the organic world--that I should point out its past condition,--that I
should state what is the precise nature of the undertaking which Mr. Darwin
has taken in hand; that I should endeavour to show you what are the only
methods by which that undertaking can be brought to an issue, and to point
out to you how far the author of the work in question has satisfied those
conditions, how far he has not satisfied them, how far they are satisfiable
by man, and how far they are not satisfiable by man.

To-night, in taking up the first part of the question, I shall endeavour to
put before you a sort of broad notion of our knowledge of the condition of
the living world. There are many ways of doing this. I might deal with it
pictorially and graphically. Following the example of Humboldt in his
"Aspects of Nature," I might endeavour to point out the infinite variety of
organic life in every mode of its existence, with reference to the
variations of climate and the like; and such an attempt would be fraught
with interest to us all; but considering the subject before us, such a
course would not be that best calculated to assist us. In an argument of
this kind we must go further and dig deeper into the matter; we must
endeavour to look into the foundations of living Nature, if I may so say,
and discover the principles involved in some of her most secret operations.
I propose, therefore, in the first place, to take some ordinary animal with
which you are all familiar, and by easily comprehensible and obvious
examples drawn from it, to show what are the kind of problems which living
beings in general lay before us; and I shall then show you that the same
problems are laid open to us by all kinds of living beings. But, first, let
me say in what sense I have used the words "organic nature." In speaking of
the causes which lead to our present knowledge of organic nature, I have
used it almost as an equivalent of the word "living," and for this
reason,--that in almost all living beings you can distinguish several
distinct portions set apart to do particular things and work in a
particular way. These are termed "organs," and the whole together is called
"organic." And as it is universally characteristic of them, the term
"organic" has been very conveniently employed to denote the whole of living
nature,--the whole of the plant world, and the whole of the animal world.

Few animals can be more familiar to you than that whose skeleton is shown
on our diagram. You need not bother yourselves with this "_Equus
caballus_" written under it; that is only the Latin name of it, and does
not make it any better. It simply means the common horse. Suppose we wish
to understand all about the horse. Our first object must be to study the
structure of the animal. The whole of his body is inclosed within a hide, a
skin covered with hair; and if that hide or skin be taken off, we find a
great mass of flesh, or what is technically called muscle, being the
substance which by its power of contraction enables the animal to move.
These muscles move the hard parts one upon the other, and so give that
strength and power of motion which renders the horse so useful to us in the
performance of those services in which we employ him.

And then, on separating and removing the whole of this skin and flesh, you
have a great series of bones, hard structures, bound together with
ligaments, and forming the skeleton which is represented here.

In that skeleton there are a number of parts to be recognised. The long
series of bones, beginning from the skull and ending in the tail, is called
the spine, and those in front are the ribs; and then there are two pairs of
limbs, one before and one behind; and there are what we all know as the
fore-legs and the hind-legs. If we pursue our researches into the interior
of this animal, we find within the framework of the skeleton a great
cavity, or rather, I should say, two great cavities,--one cavity beginning
in the skull and running through the neck-bones, along the spine, and
ending in the tail, containing the brain and the spinal marrow, which are
extremely important organs. The second great cavity, commencing with the
mouth, contains the gullet, the stomach, the long intestine, and all the
rest of those internal apparatus which are essential for digestion; and
then in the same great cavity, there are lodged the heart and all the great
vessels going from it; and, besides that, the organs of respiration--the
lungs: and then the kidneys, and the organs of reproduction, and so on. Let
us now endeavour to reduce this notion of a horse that we now have, to some
such kind of simple expressions as can be at once, and without difficulty,
retained in the mind, apart from all minor details. If I make a transverse
section, that is, if I were to saw a dead horse across, I should find that,
if I left out the details, and supposing I took my section through the
anterior region, and through the fore-limbs, I should have here this kind
of section of the body (Fig. 1).

[Illustration: Fig. 1]

Here would be the upper part of the animal--that great mass of bones that
we spoke of as the spine (_a_, Fig. 1). Here I should have the
alimentary canal (_b_, Fig. 1). Here I should have the heart
(_c_, Fig. 1); and then you see, there would be a kind of double tube,
the whole being inclosed within the hide; the spinal marrow would be placed
in the upper tube (_a_, Fig. 1), and in the lower tube (_d d_,
Fig. 1), there would be the alimentary canal (_b_), and the heart
(_e_); and here I shall have the legs proceeding from each side. For
simplicity's sake, I represent them merely as stumps (_e e_, Fig. 1).
Now that is a horse--as mathematicians would say--reduced to its most
simple expression. Carry that in your minds, if you please, as a simplified
idea of the structure of the horse. The considerations which I have now put
before you belong to what we technically call the "Anatomy" of the horse.
Now, suppose we go to work upon these several parts,--flesh and hair, and
skin and bone, and lay open these various organs with our scalpels, and
examine them by means of our magnifying-glasses, and see what we can make
of them. We shall find that the flesh is made up of bundles of strong
fibres The brain and nerves, too, we shall find are made up of fibres, and
these queer-looking things that are called ganglionic corpuscles. If we
take a slice of the bone and examine it, we shall find that it is very like
this diagram of a section of the bone of on ostrich, though differing, of
course, in some details; and if we take any part whatsoever of the tissue,
and examine it, we shall find it all has a minute structure, visible only
under the microscope. All these parts constitute microscopic anatomy or
"Histology." These parts are constantly being changed; every part is
constantly growing, decaying, and being replaced during the life of the
animal. The tissue is constantly replaced by new material; and if you go
back to the young state of the tissue in the case of muscle, or in the case
of skin, or any of the organs I have mentioned, you will find that they all
come under the same condition. Every one of these microscopic filaments and
fibres (I now speak merely of the general character of the whole
process)--every one of these parts--could be traced down to some
modification of a tissue which can be readily divided into little particles
of fleshy matter, of that substance which is composed of the chemical
elements, carbon, hydrogen, oxygen, and nitrogen, having such a shape as
this (Fig. 2). These particles, into which all primitive tissues break up,
are called cells. If I were to make a section of a piece of the skin of my
hand, I should find that it was made up of these cells. If I examine the
fibres which form the various organs of all living animals, I should find
that all of them, at one time or other, had been formed out of a substance
consisting of similar elements; so that you see, just as we reduced the
whole body in the gross to that sort of simple expression given in Fig. 1,
so we may reduce the whole of the microscopic structural elements to a form
of even greater simplicity; just as the plan of the whole body may be so
represented in a sense (Fig. 1), so the primary structure of every tissue
may be represented by a mass of cells (Fig. 2).

[Illustration: Fig. 2.]

Having thus, in this sort of general way, sketched to you what I may call,
perhaps, the architecture of the body of the horse (what we term
technically its Morphology), I must now turn to another aspect. A horse is
not a mere dead structure: it is an active, living, working machine.
Hitherto we have, as it were, been looking at a steam-engine with the fires
out, and nothing in the boiler; but the body of the living animal is a
beautifully-formed active machine, and every part has its different work to
do in the working of that machine, which is what we call its life. The
horse, if you see him after his day's work is done, is cropping the grass
in the fields, as it may be, or munching the oats in his stable. What is he
doing? His jaws are working as a mill--and a very complex mill
too--grinding the corn, or crushing the grass to a pulp. As soon as that
operation has taken place, the food is passed down to the stomach, and
there it is mixed with the chemical fluid called the gastric juice, a
substance which has the peculiar property of making soluble and dissolving
out the nutritious matter in the grass, and leaving behind those parts
which are not nutritious; so that you have, first, the mill, then a sort of
chemical digester; and then the food, thus partially dissolved, is carried
back by the muscular contractions of the intestines into the hinder parts
of the body, while the soluble portions are taken up into the blood. The
blood is contained in a vast system of pipes, spreading through the whole
body, connected with a force-pump,--the heart,--which, by its position and
by the contractions of its valves, keeps the blood constantly circulating
in one direction, never allowing it to rest; and then, by means of this
circulation of the blood, laden as it is with the products of digestion,
the skin, the flesh, the hair, and every other part of the body, draws from
it that which it wants, and every one of these organs derives those
materials which are necessary to enable it to do its work.

The action of each of these organs, the performance of each of these
various duties, involve in their operation a continual absorption of the
matters necessary for their support, from the blood and a constant
formation of waste products, which are returned to the blood, and conveyed
by it to the lungs and the kidneys, which are organs that have allotted to
them the office of extracting, separating, and getting rid of these waste
products; and thus the general nourishment, labour, and repair of the whole
machine are kept up with order and regularity. But not only is it a machine
which feeds and appropriates to its own support the nourishment necessary
to its existence--it is an engine for locomotive purposes. The horse
desires to go from one place to another; and to enable it to do this, it
has those strong contractile bundles of muscles attached to the bones of
its limbs, which are put in motion by means of a sort of telegraphic
apparatus formed by the brain and the great spinal cord running through the
spine or backbone; and to this spinal cord are attached a number of fibres
termed nerves, which proceed to all parts of the structure. By means of
these the eyes, nose, tongue, and skin--all the organs of
perception--transmit impressions or sensations to the brain, which acts as
a sort of great central telegraph-office, receiving impressions and sending
messages to all parts of the body, and putting in motion the muscles
necessary to accomplish any movement that maybe desired. So that you have
here an extremely complex and beautifully-proportioned machine, with all
its parts working harmoniously together towards one common object--the
preservation of the life of the animal.

Now, note this: the horse makes up its waste by feeding, and its food is
grass or oats, or perhaps other vegetable products; therefore, in the long
run, the source of all this complex machinery lies in the vegetable
kingdom. But where does the grass, or the oat, or any other plant obtain
this nourishing food-producing material? At first it is a little seed,
which soon begins to draw into itself from the earth and the surrounding
air matters which in themselves contain no vital properties whatever; it
absorbs into its own substance water, an inorganic body; it draws into its
substance carbonic acid, an inorganic matter; and ammonia, another
inorganic matter, found in the air; and then, by some wonderful chemical
process, the details of which chemists do not yet understand, though they
are near foreshadowing them, it combines them into one substance, which is
known to us as "Protein," a complex compound of carbon, hydrogen, oxygen,
and nitrogen, which alone possesses the property of manifesting vitality
and of permanently supporting animal life. So that, you see, the waste
products of the animal economy, the effete materials which are continually
being thrown off by all living beings, in the form of organic matters, are
constantly replaced by supplies of the necessary repairing and rebuilding
materials drawn from the plants, which in their turn manufacture them, so
to speak, by a mysterious combination of those same inorganic materials.

Let us trace out the history of the horse in another direction. After a
certain time, as the result of sickness or disease, the effect of accident,
or the consequence of old age, sooner or later, the animal dies. The
multitudinous operations of this beautiful mechanism flag in their
performance, the horse loses its vigour, and after passing through the
curious series of changes comprised in its formation and preservation, it
finally decays, and ends its life by going back into that inorganic world
from which all but an inappreciable fraction of its substance was derived.
Its bones become mere carbonate and phosphate of lime; the matter of its
flesh, and of its other parts, becomes, in the long run, converted into
carbonic acid, into water, and into ammonia. You will now, perhaps,
understand the curious relation of the animal with the plant, of the
organic with the inorganic world, which is shown in this diagram.

[Illustration: Inorganic World Fig. 3.]

The plant gathers these inorganic materials together and makes them up into
its own substance. The animal eats the plant and appropriates the
nutritious portions to its own sustenance, rejects and gets rid of the
useless matters; and, finally, the animal itself dies, and its whole body
is decomposed and returned into the inorganic world. There is thus a
constant circulation from one to the other, a continual formation of
organic life from inorganic matters, and as constant a return of the matter
of living bodies to the inorganic world; so that the materials of which our
bodies are composed are largely, in all probability, the substances which
constituted the matter of long extinct creations, but which have in the
interval constituted a part of the inorganic world.

Thus we come to the conclusion, strange at first sight, that the MATTER
constituting the living world is identical with that which forms the
inorganic world. And not less true is it that, remarkable as are the powers
or, in other words, as are the FORCES which are exerted by living beings,
yet all these forces are either identical with those which exist in the
inorganic world, or they are convertible into them; I mean in just the same
sense as the researches of physical philosophers have shown that heat is
convertible into electricity, that electricity is convertible into
magnetism, magnetism into mechanical force or chemical force, and any one
of them with the other, each being measurable in terms of the other,--even
so, I say, that great law is applicable to the living world. Consider why
is the skeleton of this horse capable of supporting the masses of flesh and
the various organs forming the living body, unless it is because of the
action of the same forces of cohesion which combines together the particles
of matter composing this piece of chalk? What is there in the muscular
contractile power of the animal but the force which is expressible, and
which is in a certain sense convertible, into the force of gravity which it
overcomes? Or, if you go to more hidden processes, in what does the process
of digestion differ from those processes which are carried on in the
laboratory of the chemist? Even if we take the most recondite and most
complex operations of animal life--those of the nervous system, these of
late years have been shown to be--I do not say identical in any sense with
the electrical processes--but this has been shown, that they are in some
way or other associated with them; that is to say, that every amount of
nervous action is accompanied by a certain amount of electrical disturbance
in the particles of the nerves in which that nervous action is carried on.
In this way the nervous action is related to electricity in the same way
that heat is related to electricity; and the same sort of argument which
demonstrates the two latter to be related to one another shows that the
nervous forces are correlated to electricity; for the experiments of M.
Dubois Reymond and others have shown that whenever a nerve is in a state of
excitement, sending a message to the muscles or conveying an impression to
the brain, there is a disturbance of the electrical condition of that nerve
which does not exist at other times; and there are a number of other facts
and phenomena of that sort; so that we come to the broad conclusion that
not only as to living matter itself, but as to the forces that matter
exerts, there is a close relationship between the organic and the inorganic
world--the difference between them arising from the diverse combination and
disposition of identical forces, and not from any primary diversity, so far
as we can see.

I said just now that the horse eventually died and became converted into
the same inorganic substances from whence all but an inappreciable fraction
of its substance demonstrably originated, so that the actual wanderings of
matter are as remarkable as the transmigrations of the soul fabled by
Indian tradition. But before death has occurred, in the one sex or the
other, and in fact in both, certain products or parts of the organism have
been set free, certain parts of the organisms of the two sexes have come
into contact with one another, and from that conjunction, from that union
which then takes place, there results the formation of a new being. At
stated times the mare, from a particular part of the interior of her body,
called the ovary, gets rid of a minute particle of matter comparable in all
essential respects with that which we called a cell a little while since,
which cell contains a kind of nucleus in its centre, surrounded by a clear
space and by a viscid mass of protein substance (Fig. 2); and though it is
different in appearance from the eggs which we are mostly acquainted with,
it is really an egg. After a time this minute particle of matter, which may
only be a small fraction of a grain in weight, undergoes a series of
changes,--wonderful, complex changes. Finally, upon its surface there is
fashioned a little elevation, which afterwards becomes divided and marked
by a groove. The lateral boundaries of the groove extend upwards and
downwards, and at length give rise to a double tube. In the upper and
smaller tube the spinal marrow and brain are fashioned; in the lower, the
alimentary canal and heart; and at length two pairs of buds shoot out at
the sides of the body, and they are the rudiments of the limbs. In fact a
true drawing of a section of the embryo in this state would in all
essential respects resemble that diagram of a horse reduced to its simplest
expression, which I first placed before you (Fig. 1).

Slowly and gradually these changes take place. The whole of the body, at
first, can be broken up into "cells," which become in one place
metamorphosed into muscle,--in another place into gristle and bone,--in
another place into fibrous tissue,--and in another into hair; every part
becoming gradually and slowly fashioned, as if there were an artificer at
work in each of these complex structures that I have mentioned. This
embryo, as it is called, then passes into other conditions. I should tell
you that there is a time when the embryos of neither dog, nor horse, nor
porpoise, nor monkey, nor man, can be distinguished by any essential
feature one from the other; there is a time when they each and all of them
resemble this one of the dog. But as development advances, all the parts
acquire their speciality, till at length you have the embryo converted into
the form of the parent from which it started. So that you see, this living
animal, this horse, begins its existence as a minute particle of
nitrogenous matter, which, being supplied with nutriment (derived, as I
have shown, from the inorganic world), grows up according to the special
type and construction of its parents, works and undergoes a constant waste,
and that waste is made good by nutriment derived from the inorganic world;
the waste given off in this way being directly added to the inorganic
world. Eventually the animal itself dies, and, by the process of
decomposition, its whole body is returned to those conditions of inorganic
matter in which its substance originated.

This, then, is that which is true of every living form, from the lowest
plant to the highest animal--to man himself. You might define the life of
every one in exactly the same terms as those which I have now used; the
difference between the highest and the lowest being simply in the
complexity of the developmental changes, the variety of the structural
forms, and the diversity of the physiological functions which are exerted
by each.

If I were to take an oak tree, as a specimen of the plant world, I should
find that it originated in an acorn, which, too, commenced in a cell; the
acorn is placed in the ground, and it very speedily begins to absorb the
inorganic matters I have named, adds enormously to its bulk, and we can see
it, year after year, extending itself upward and downward, attracting and
appropriating to itself inorganic materials, which it vivifies, and
eventually, as it ripens, gives off its own proper acorns, which again run
the same course. But I need not multiply examples,--from the highest to the
lowest the essential features of life are the same as I have described in
each of these cases.

So much, then, for these particular features of the organic world, which
you can understand and comprehend, so long as you confine yourself to one
sort of living being, and study that only.

But, as you know, horses are not the only living creatures in the world;
and again, horses, like all other animals, have certain limits--are
confined to a certain area on the surface of the earth on which we
live,--and, as that is the simpler matter, I may take that first. In its
wild state, and before the discovery of America, when the natural state of
things was interfered with by the Spaniards, the horse was only to be found
in parts of the earth which are known to geographers as the Old World; that
is to say, you might meet with horses in Europe, Asia, or Africa; but there
were none in Australia, and there were none whatsoever in the whole
continent of America, from Labrador down to Cape Horn. This is an empirical
fact, and it is what is called, stated in the way I have given it you, the
"Geographical Distribution" of the horse.

Why horses should be found in Europe, Asia, and Africa, and not in America,
is not obvious; the explanation that the conditions of life in America are
unfavourable to their existence, and that, therefore, they had not been
created there, evidently does not apply; for when the invading Spaniards,
or our own yeomen farmers, conveyed horses to these countries for their own
use, they were found to thrive well and multiply very rapidly; and many are
even now running wild in those countries, and in a perfectly natural
condition. Now, suppose we were to do for every animal what we have here
done for the horse,--that is, to mark off and distinguish the particular
district or region to which each belonged; and supposing we tabulated all
these results, that would be called the Geographical Distribution of
animals, while a corresponding study of plants would yield as a result the
Geographical Distribution of plants.

I pass on from that now, as I merely wished to explain to you what I meant
by the use of the term "Geographical Distribution." As I said, there is
another aspect, and a much more important one, and that is, the relations
of the various animals to one another. The horse is a very well-defined
matter-of-fact sort of animal, and we are all pretty familiar with its
structure. I dare say it may have struck you, that it resembles very much
no other member of the animal kingdom, except perhaps the zebra or the ass.
But let me ask you to look along these diagrams. Here is the skeleton of
the horse, and here the skeleton of the dog. You will notice that we have
in the horse a skull, a backbone and ribs, shoulder-blades and
haunch-bones. In the fore-limb, one upper arm-bone, two fore arm-bones,
wrist-bones (wrongly called knee), and middle hand-bones, ending in the
three bones of a finger, the last of which is sheathed in the horny hoof of
the fore-foot: in the hind-limb, one thigh-bone, two leg-bones,
ankle-bones, and middle foot-bones, ending in the three bones of a toe, the
last of which is encased in the hoof of the hind-foot. Now turn to the
dog's skeleton. We find identically the same bones, but more of them, there
being more toes in each foot, and hence more toe-bones.

Well, that is a very curious thing! The fact is that the dog and the
horse--when one gets a look at them without the outward impediments of the
skin--are found to be made in very much the same sort of fashion. And if I
were to make a transverse section of the dog, I should find the same organs
that I have already shown you as forming parts of the horse. Well, here is
another skeleton--that of a kind of lemur--you see he has just the same
bones; and if I were to make a transverse section of it, it would be just
the same again. In your mind's eye turn him round, so as to put his
backbone in a position inclined obliquely upwards and forwards, just as in
the next three diagrams, which represent the skeletons of an orang, a
chimpanzee, and a gorilla, and you find you have no trouble in identifying
the bones throughout; and lastly turn to the end of the series, the diagram
representing a man's skeleton, and still you find no great structural
feature essentially altered. There are the same bones in the same
relations. From the horse we pass on and on, with gradual steps until we
arrive at last at the highest known forms. On the other hand, take the
other line of diagrams, and pass from the horse downwards in the scale to
this fish; and still, though the modifications are vastly greater, the
essential framework of the organisation remains unchanged. Here, for
instance, is a porpoise: here is its strong backbone, with the cavity
running through it, which contains the spinal cord; here are the ribs, here
the shoulder-blade; here is the little short upper-arm bone, here are the
two forearm bones, the wrist-bone, and the finger-bones.

Strange, is it not, that the porpoise should have in this queer-looking
affair--its flapper (as it is called), the same fundamental elements as the
fore-leg of the horse or the dog, or the ape or man; and here you will
notice a very curious thing,--the hinder limbs are absent. Now, let us make
another jump. Let us go to the codfish: here you see is the forearm, in
this large pectoral fin--carrying your mind's eye onward from the flapper
of the porpoise. And here you have the hinder limbs restored in the shape
of these ventral fins. If I were to make a transverse section of this, I
should find just the same organs that we have before noticed. So that, you
see, there comes out this strange conclusion as the result of our
investigations, that the horse, when examined and compared with other
animals, is found by no means to stand alone in Nature; but that there are
an enormous number of other creatures which have backbones, ribs, and legs,
and other parts arranged in the same general manner, and in all their
formation exhibiting the same broad peculiarities.

I am sure that you cannot have followed me even in this extremely
elementary exposition of the structural relations of animals, without
seeing what I have been driving at all through, which is, to show you that,
step by step, naturalists have come to the idea of a unity of plan, or
conformity of construction, among animals which appeared at first sight to
be extremely dissimilar.

And here you have evidence of such a unity of plan among all the animals
which have backbones, and which we technically call _Vertebrata_. But
there are multitudes of other animals, such as crabs, lobsters, spiders,
and so on, which we term _Annulosa_. In these I could not point out to
you the parts that correspond with those of the horse,--the backbone, for
instance,--as they are constructed upon a very different principle, which
is also common to all of them; that is to say, the lobster, the spider, and
the centipede, have a common plan running through their whole arrangement,
in just the same way that the horse, the dog, and the porpoise assimilate
to each other.

Yet other creatures--whelks, cuttlefishes, oysters, snails, and all their
tribe (_Mollusca_)--resemble one another in the same way, but differ
from both _Vertebrata_ and _Annulosa_; and the like is true of
the animals called _Coelenterata_ (Polypes) and _Protozoa_
(animalcules and sponges).

Now, by pursuing this sort of comparison, naturalists have arrived at the
conviction that there are,--some think five, and some seven,--but certainly
not more than the latter number--and perhaps it is simpler to assume
five--distinct plans or constructions in the whole of the animal world; and
that the hundreds of thousands of species of creatures on the surface of
the earth, are all reducible to those five, or, at most, seven, plans of
organisation.

But can we go no further than that? When one has got so far, one is tempted
to go on a step and inquire whether we cannot go back yet further and bring
down the whole to modifications of one primordial unit. The anatomist
cannot do this; but if he call to his aid the study of development, he can
do it. For we shall find that, distinct as those plans are, whether it be a
porpoise or man, or lobster, or any of those other kinds I have mentioned,
every one begins its existence with one and the same primitive form,--that
of the egg, consisting, as we have seen, of a nitrogenous substance, having
a small particle or nucleus in the centre of it. Furthermore, the earlier
changes of each are substantially the same. And it is in this that lies
that true "unity of organisation" of the animal kingdom which has been
guessed at and fancied for many years; but which it has been left to the
present time to be demonstrated by the careful study of development. But is
it possible to go another step further still, and to show that in the same
way the whole of the organic world is reducible to one primitive condition
of form? Is there among the plants the same primitive form of organisation,
and is that identical with that of the animal kingdom? The reply to that
question, too, is not uncertain or doubtful. It is now proved that every
plant begins its existence under the same form; that is to say, in that of
a cell--a particle of nitrogenous matter having substantially the same
conditions. So that if you trace back the oak to its first germ, or a man,
or a horse, or lobster, or oyster, or any other animal you choose to name,
you shall find each and all of these commencing their existence in forms
essentially similar to each other; and, furthermore, that the first
processes of growth, and many of the subsequent modifications, are
essentially the same in principle in almost all.

In conclusion, let me, in a few words, recapitulate the positions which I
have laid down. And you must understand that I have not been talking mere
theory; I have been speaking of matters which are as plainly demonstrable
as the commonest propositions of Euclid--of facts that must form the basis
of all speculations and beliefs in Biological science. We have gradually
traced down all organic forms, or, in other words, we have analysed the
present condition of animated nature, until we found that each species took
its origin in a form similar to that under which all the others commenced
their existence. We have found the whole of the vast array of living forms
with which we are surrounded, constantly growing, increasing, decaying and
disappearing; the animal constantly attracting, modifying, and applying to
its sustenance the matter of the vegetable kingdom, which derived its
support from the absorption and conversion of inorganic matter. And so
constant and universal is this absorption, waste, and reproduction, that it
may be said with perfect certainty that there is left in no one of our
bodies at the present moment a millionth part of the matter of which they
were originally formed! We have seen, again, that not only is the living
matter derived from the inorganic world, but that the forces of that matter
are all of them correlative with and convertible into those of inorganic
nature.

This, for our present purposes, is the best view of the present condition
of organic nature which I can lay before you: it gives you the great
outlines of a vast picture, which you must fill up by your own study.

In the next lecture I shall endeavour in the same way to go back into the
past, and to sketch in the same broad manner the history of life in epochs
preceding our own.



II. THE PAST CONDITION OF ORGANIC NATURE


In the lecture which I delivered last Monday evening, I endeavoured to
sketch in a very brief manner, but as well as the time at my disposal would
permit, the present condition of organic nature, meaning by that large
title simply an indication of the great, broad, and general principles
which are to be discovered by those who look attentively at the phenomena
of organic nature as at present displayed. The general result of our
investigations might be summed up thus: we found that the multiplicity of
the forms of animal life, great as that may be, may be reduced to a
comparatively few primitive plans or types of construction; that a further
study of the development of those different forms revealed to us that they
were again reducible, until we at last brought the infinite diversity of
animal, and even vegetable life, down to the primordial form of a single
cell.

We found that our analysis of the organic world, whether animals or plants,
showed, in the long run, that they might both be reduced into, and were, in
fact, composed of, the same constituents. And we saw that the plant
obtained the materials constituting its substance by a peculiar combination
of matters belonging entirely to the inorganic world; that, then, the
animal was constantly appropriating the nitrogenous matters of the plant to
its own nourishment, and returning them back to the inorganic world, in
what we spoke of as its waste; and that finally, when the animal ceased to
exist, the constituents of its body were dissolved and transmitted to that
inorganic world whence they had been at first abstracted. Thus we saw in
both the blade of grass and the horse but the same elements differently
combined and arranged. We discovered a continual circulation going on,--the
plant drawing in the elements of inorganic nature and combining them into
food for the animal creation; the animal borrowing from the plant the
matter for its own support, giving off during its life products which
returned immediately to the inorganic world; and that, eventually, the
constituent materials of the whole structure of both animals and plants
were thus returned to their original source: there was a constant passage
from one state of existence to another, and a returning back again.

Lastly, when we endeavoured to form some notion of the nature of the forces
exercised by living beings, we discovered that they--if not capable of
being subjected to the same minute analysis as the constituents of those
beings themselves--that they were correlative with--that they were the
equivalents of the forces of inorganic nature--that they were, in the sense
in which the term is now used, convertible with them. That was our general
result.

And now, leaving the Present, I must endeavour in the same manner to put
before you the facts that are to be discovered in the Past history of the
living world, in the past conditions of organic nature. We have, to-night,
to deal with the facts of that history--a history involving periods of time
before which our mere human records sink into utter insignificance--a
history the variety and physical magnitude of whose events cannot even be
foreshadowed by the history of human life and human phenomena--a history of
the most varied and complex character.

We must deal with the history, then, in the first place, as we should deal
with all other histories. The historical student knows that his first
business should be to inquire into the validity of his evidence, and the
nature of the record in which the evidence is contained, that he may be
able to form a proper estimate of the correctness of the conclusions which
have been drawn from that evidence. So, here we must pass, in the first
place, to the consideration of a matter which may seem foreign to the
question under discussion. We must dwell upon the nature of the records,
and the credibility of the evidence they contain; we must look to the
completeness or incompleteness of those records themselves, before we turn
to that which they contain and reveal. The question of the credibility of
the history, happily for us, will not require much consideration, for, in
this history, unlike those of human origin, there can be no cavilling, no
differences as to the reality and truth of the facts of which it is made
up; the facts state themselves, and are laid out clearly before us.

But, although one of the greatest difficulties of the historical student is
cleared out of our path, there are other difficulties--difficulties in
rightly interpreting the facts as they are presented to us--which may be
compared with the greatest difficulties of any other kinds of historical
study.

What is this record of the past history of the globe, and what are the
questions which are involved in an inquiry into its completeness or
incompleteness? That record is composed of mud; and the question which we
have to investigate this evening resolves itself into a question of the
formation of mud. You may think, perhaps, that this is a vast step--of
almost from the sublime to the ridiculous--from the contemplation of the
history of the past ages of the world's existence to the consideration of
the history of the formation of mud! But, in Nature, there is nothing mean
and unworthy of attention; there is nothing ridiculous or contemptible in
any of her works; and this inquiry, you will soon see, I hope, takes us to
the very root and foundations of our subject.

How, then, is mud formed? Always, with some trifling exceptions, which I
need not consider now--always, as the result of the action of water,
wearing down and disintegrating the surface of the earth and rocks with
which it comes in contact--pounding and grinding it down, and carrying the
particles away to places where they cease to be disturbed by this
mechanical action, and where they can subside and rest. For the ocean,
urged by winds, washes, as we know, a long extent of coast, and every wave,
loaded as it is with particles of sand and gravel as it breaks upon the
shore, does something towards the disintegrating process. And thus, slowly
but surely, the hardest rocks are gradually ground down to a powdery
substance; and the mud thus formed, coarser or finer, as the case may be,
is carried by the rush of the tides, or currents, till it reaches the
comparatively deeper parts of the ocean, in which it can sink to the
bottom, that is, to parts where there is a depth of about fourteen or
fifteen fathoms, a depth at which the water is, usually, nearly motionless,
and in which, of course, the finer particles of this detritus, or mud as we
call it, sinks to the bottom.

Or, again, if you take a river, rushing down from its mountain sources,
brawling over the stones and rocks that intersect its path, loosening,
removing, and carrying with it in its downward course the pebbles and
lighter matters from its banks, it crushes and pounds down the rocks and
earths in precisely the same way as the wearing action of the sea waves.
The matters forming the deposit are torn from the mountain-side and whirled
impetuously into the valley, more slowly over the plain, thence into the
estuary, and from the estuary they are swept into the sea. The coarser and
heavier fragments are obviously deposited first, that is, as soon as the
current begins to lose its force by becoming amalgamated with the stiller
depths of the ocean, but the finer and lighter particles are carried
further on, and eventually deposited in a deeper and stiller portion of the
ocean.

It clearly follows from this that mud gives us a chronology; for it is
evident that supposing this, which I now sketch, to be the sea bottom, and
supposing this to be a coast-line; from the washing action of the sea upon
the rock, wearing and grinding it down into a sediment of mud, the mud will
be carried down, and, at length, deposited in the deeper parts of this sea
bottom, where it will form a layer; and then, while that first layer is
hardening, other mud which is coming from the same source will, of course,
be carried to the same place; and, as it is quite impossible for it to get
beneath the layer already there, it deposits itself above it, and forms
another layer, and in that way you gradually have layers of mud constantly
forming and hardening one above the other, and conveying a record of time.

It is a necessary result of the operation of the law of gravitation that
the uppermost layer shall be the youngest and the lowest the oldest, and
that the different beds shall be older at any particular point or spot in
exactly the ratio of their depth from the surface. So that if they were
upheaved afterwards, and you had a series of these different layers of mud,
converted into sandstone, or limestone, as the case might be, you might be
sure that the bottom layer was deposited first, and that the upper layers
were formed afterwards. Here, you see, is the first step in the
history--these layers of mud give us an idea of time.

The whole surface of the earth,--I speak broadly, and leave out minor
qualifications,--is made up of such layers of mud, so hard, the majority of
them, that we call them rock whether limestone or sandstone, or other
varieties of rock. And, seeing that every part of the crust of the earth is
made up in this way, you might think that the determination of the
chronology, the fixing of the time which it has taken to form this crust is
a comparatively simple matter. Take a broad average, ascertain how fast the
mud is deposited upon the bottom of the sea, or in the estuary of rivers;
take it to be an inch, or two, or three inches a year, or whatever you may
roughly estimate it at; then take the total thickness of the whole series
of stratified rocks, which geologists estimate at twelve or thirteen miles,
or about seventy thousand feet, make a sum in short division, divide the
total thickness by that of the quantity deposited in one year, and the
result will, of course, give you the number of years which the crust has
taken to form.

Truly, that looks a very simple process! It would be so except for certain
difficulties, the very first of which is that of finding how rapidly
sediments are deposited; but the main difficulty--a difficulty which
renders any certain calculations of such a matter out of the question--is
this, the sea-bottom on which the deposit takes place is continually
shifting.

Instead of the surface of the earth being that stable, fixed thing that it
is popularly believed to be, being, in common parlance, the very emblem of
fixity itself, it is incessantly moving, and is, in fact, as unstable as
the surface of the sea, except that its undulations are infinitely slower
and enormously higher and deeper.

Now, what is the effect of this oscillation? Take the case to which I have
previously referred. The finer or coarser sediments that are carried down
by the current of the river, will only be carried out a certain distance,
and eventually, as we have already seen, on reaching the stiller part of
the ocean, will be deposited at the bottom.

[Illustration: Fig. 4.]

Let C _y_ (Fig. 4) be the sea-bottom, _y_ D the shore, _x y_
the sea-level, then the coarser deposit will subside over the region B, the
finer over A, while beyond A there will be no deposit at all; and,
consequently, no record will be kept, simply because no deposit is going
on. Now, suppose that the whole land, C, D, which we have regarded as
stationary, goes down, as it does so, both A and B go further out from the
shore, which will be at _y1_; _x1_, _y1_, being the new
sea-level. The consequence will be that the layer of mud (A), being now,
for the most part, further than the force of the current is strong enough
to convey even the finest _débris_, will, of course, receive no more
deposits, and having attained a certain thickness will now grow no thicker.

We should be misled in taking the thickness of that layer, whenever it may
be exposed to our view, as a record of time in the manner in which we are
now regarding this subject, as it would give us only an imperfect and
partial record: it would seem to represent too short a period of time.

Suppose, on the other hand, that the land (C D) had gone on rising slowly
and gradually--say an inch or two inches in the course of a century,--what
would be the practical effect of that movement? Why, that the sediment A
and B which has been already deposited, would eventually be brought nearer
to the shore-level and again subjected to the wear and tear of the sea; and
directly the sea begins to act upon it, it would of course soon cut up and
carry it way, to a greater or less extent, to be re-deposited further out.

Well, as there is, in all probability, not one single spot on the whole
surface of the earth, which has not been up and down in this way a great
many times, it follows that the thickness of the deposits formed at any
particular spot cannot be taken (even supposing we had at first obtained
correct data as to the rate at which they took place), as affording
reliable information as to the period of time occupied in its deposit. So
that you see it is absolutely necessary from these facts, seeing that our
record entirely consists of accumulations of mud, superimposed one on the
other; seeing in the next place that any particular spots on which
accumulations have occurred, have been constantly moving up and down, and
sometimes out of the reach of a deposit, and at other times its own deposit
broken up and carried away, it follows that our record must be in the
highest degree imperfect, and we have hardly a trace left of thick
deposits, or any definite knowledge of the area that they occupied, in a
great many cases. And mark this! That supposing even that the whole surface
of the earth had been accessible to the geologist,--that man had had access
to every part of the earth, and had made sections of the whole, and put
them all together,--even then his record must of necessity be imperfect.

But to how much has man really access? If you will look at this map you
will see that it represents the proportion of the sea to the earth: this
coloured part indicates all the dry land, and this other portion is the
water. You will notice at once that the water covers three-fifths of the
whole surface of the globe, and has covered it in the same manner ever
since man has kept any record of his own observations, to say nothing of
the minute period during which he has cultivated geological inquiry. So
that three-fifths of the surface of the earth is shut out from us because
it is under the sea. Let us look at the other two-fifths, and see what are
the countries in which anything that may be termed searching geological
inquiry has been carried out: a good deal of France, Germany, and Great
Britain and Ireland, bits of Spain, of Italy, and of Russia, have been
examined, but of the whole great mass of Africa, except parts of the
southern extremity, we know next to nothing; little bits of India, but of
the greater part of the Asiatic continent nothing; bits of the Northern
American States and of Canada, but of the greater part of the continent of
North America, and in still larger proportion, of South America, nothing!

Under these circumstances, it follows that even with reference to that kind
of imperfect information which we can possess, it is only of about the
ten-thousandth part of the accessible parts of the earth that has been
examined properly. Therefore, it is with justice that the most thoughtful
of those who are concerned in these inquiries insist continually upon the
imperfection of the geological record; for, I repeat, it is absolutely
necessary, from the nature of things, that that record should be of the
most fragmentary and imperfect character. Unfortunately this circumstance
has been constantly forgotten. Men of science, like young colts in a fresh
pasture, are apt to be exhilarated on being turned into a new field of
inquiry, to go off at a hand-gallop, in total disregard of hedges and
ditches, to lose sight of the real limitation of their inquiries, and to
forget the extreme imperfection of what is really known. Geologists have
imagined that they could tell us what was going on at all parts of the
earth's surface during a given epoch; they have talked of this deposit
being contemporaneous with that deposit, until, from our little local
histories of the changes at limited spots of the earth's surface, they have
constructed a universal history of the globe as full of wonders and
portents as any other story of antiquity.

But what does this attempt to construct a universal history of the globe
imply? It implies that we shall not only have a precise knowledge of the
events which have occurred at any particular point, but that we shall be
able to say what events, at any one spot, took place at the same time with
those at other spots.

Let us see how far that is in the nature of things practicable. Suppose
that here I make a section of the Lake of Killarney, and here the section
of another lake--that of Loch Lomond in Scotland for instance. The rivers
that flow into them are constantly carrying down deposits of mud, and beds,
or strata, are being as constantly formed, one above the other, at the
bottom of those lakes. Now, there is not a shadow of doubt that in these
two lakes the lower beds are all older than the upper--there is no doubt
about that; but what does _this_ tell us about the age of any given
bed in Loch Lomond, as compared with that of any given bed in the Lake of
Killarney? It is, indeed, obvious that if any two sets of deposits are
separated and discontinuous, there is absolutely no means whatever given
you by the nature of the deposit of saying whether one is much younger or
older than the other; but you may say, as many have said and think, that
the case is very much altered if the beds which we are comparing are
continuous. Suppose two beds of mud hardened into rock,--A and B--are seen
in section. (Fig. 5.)

[Illustration: Fig. 5.]

Well, you say, it is admitted that the lowermost bed is always the older.
Very well; B, therefore, is older than A. No doubt, _as a whole_, it
is so; or if any parts of the two beds which are in the same vertical line
are compared, it is so. But suppose you take what seems a very natural step
further, and say that the part _a_ of the bed A is younger than the
part _b_ of the bed B. Is this sound reasoning? If you find any record
of changes taking place at _b_, did they occur before any events which
took place while _a_ was being deposited? It looks all very plain
sailing, indeed, to say that they did; and yet there is no proof of
anything of the kind. As the former Director of this Institution, Sir H. De
la Beche, long ago showed, this reasoning may involve an entire fallacy. It
is extremely possible that _a_ may have been deposited ages before
_b_. It is very easy to understand how that can be. To return to Fig.
4; when A and B were deposited, they were _substantially_
contemporaneous; A being simply the finer deposit, and B the coarser of the
same detritus or waste of land. Now suppose that that sea-bottom goes down
(as shown in Fig. 4), so that the first deposit is carried no farther than
_a_, forming the bed A1, and the coarse no farther than _b_,
forming the bed B1, the result will be the formation of two continuous
beds, one of fine sediment (A A1) over-lapping another of coarse sediment
(B B1). Now suppose the whole sea-bottom is raised up, and a section
exposed about the point A1; no doubt, _at this spot_, the upper bed is
younger than the lower. But we should obviously greatly err if we concluded
that the mass of the upper bed at A was younger than the lower bed at B;
for we have just seen that they are contemporaneous deposits. Still more
should we be in error if we supposed the upper bed at A to be younger than
the continuation of the lower bed at B1; for A was deposited long before
B1. In fine, if, instead of comparing immediately adjacent parts of two
beds, one of which lies upon another, we compare distant parts, it is quite
possible that the upper may be any number of years older than the under,
and the under any number of years younger than the upper.

Now you must not suppose that I put this before you for the purpose of
raising a paradoxical difficulty; the fact is, that the great mass of
deposits have taken place in sea-bottoms which are gradually sinking, and
have been formed under the very conditions I am here supposing.

Do not run away with the notion that this subverts the principle I laid
down at first. The error lies in extending a principle which is perfectly
applicable to deposits in the same vertical line to deposits which are not
in that relation to one another.

It is in consequence of circumstances of this kind, and of others that I
might mention to you, that our conclusions on and interpretations of the
record are really and strictly only valid so long as we confine ourselves
to one vertical section. I do not mean to tell you that there are no
qualifying circumstances, so that, even in very considerable areas, we may
safely speak of conformably superimposed beds being older or younger than
others at many different points. But we can never be quite sure in coming
to that conclusion, and especially we cannot be sure if there is any break
in their continuity, or any very great distance between the points to be
compared.

Well now, so much for the record itself,--so much for its
imperfections,--so much for the conditions to be observed in interpreting
it, and its chronological indications, the moment we pass beyond the limits
of a vertical linear section.

Now let us pass from the record to that which it contains,--from the book
itself to the writing and the figures on its pages. This writing and these
figures consist of remains of animals and plants which, in the great
majority of cases, have lived and died in the very spot in which we now
find them, or at least in the immediate vicinity. You must all of you be
aware--and I referred to the fact in my last lecture--that there are vast
numbers of creatures living at the bottom of the sea. These creatures, like
all others, sooner or later die, and their shells and hard parts lie at the
bottom; and then the fine mud which is being constantly brought down by
rivers and the action of the wear and tear of the sea, covers them over and
protects them from any further change or alteration; and, of course, as in
process of time the mud becomes hardened and solidified, the shells of
these animals are preserved and firmly imbedded in the limestone or
sandstone which is being thus formed. You may see in the galleries of the
Museum up stairs specimens of limestones in which such fossil remains of
existing animals are imbedded. There are some specimens in which turtles'
eggs have been imbedded in calcareous sand, and before the sun had hatched
the young turtles, they became covered over with calcareous mud, and thus
have been preserved and fossilised.

Not only does this process of imbedding and fossilisation occur with marine
and other aquatic animals and plants, but it affects those land animals and
plants which are drifted away to sea, or become buried in bogs or morasses;
and the animals which have been trodden down by their fellows and crushed
in the mud at the river's bank, as the herd have come to drink. In any of
these cases, the organisms may be crushed or be mutilated, before or after
putrefaction, in such a manner that perhaps only a part will be left in the
form in which it reaches us. It is, indeed, a most remarkable fact, that it
is quite an exceptional case to find a skeleton of any one of all the
thousands of wild land animals that we know are constantly being killed, or
dying in the course of nature: they are preyed on and devoured by other
animals, or die in places where their bodies are not afterwards protected
by mud. There are other animals existing on the sea, the shells of which


 


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