the leading facts and inferences briefly recapitulated.

That many and grave objections may be advanced against the theory of descent with modification

through natural selection, I do not deny. I have endeavoured to give to them their full

force. Nothing at first can appear more difficult to believe than that the more complex organs

and instincts should have been perfected not by means superior to, though analogous with,

human reason, but by the accumulation of innumerable slight variations, each good for the individual

possessor. Nevertheless, this difficulty, though appearing to our imagination insuperably

great, cannot be considered real if we admit the following propositions, namely, -- that

gradations in the perfection of any organ or instinct, which we may consider, either

do now exist or could have existed, each good of its kind, -- that all organs and instincts

are, in ever so slight a degree, variable, -- and, lastly, that there is a struggle for

existence leading to the preservation of each profitable deviation of structure or instinct.

The truth of these propositions cannot, I think, be disputed.

Turning to geographical distribution, the difficulties encountered on the theory of

descent with modification are grave enough. All the individuals of the same species, and

all the species of the same genus, or even higher group, must have descended from common

parents; and therefore, in however distant and isolated parts of the world they are now

found, they must in the course of successive generations have passed from some one part

to the others. We are often wholly unable even to conjecture how this could have been

effected. Yet, as we have reason to believe that some species have retained the same specific

form for very long periods, enormously long as measured by years, too much stress ought

not to be laid on the occasional wide diffusion of the same species; for during very long

periods of time there will always be a good chance for wide migration by many means. A

broken or interrupted range may often be accounted for by the extinction of the species in the

intermediate regions. It cannot be denied that we are as yet very ignorant of the full

extent of the various climatal and geographical changes which have affected the earth during

modern periods; and such changes will obviously have greatly facilitated migration.

On this doctrine of the extermination of an infinitude of connecting links, between the

living and extinct inhabitants of the world, and at each successive period between the

extinct and still older species, why is not every geological formation charged with such

links? Why does not every collection of fossil remains afford plain evidence of the gradation

and mutation of the forms of life? We meet with no such evidence, and this is the most

obvious and forcible of the many objections which may be urged against my theory. Why,

again, do whole groups of allied species appear, though certainly they often falsely appear,

to have come in suddenly on the several geological stages? Why do we not find great piles of

strata beneath the Silurian system, stored with the remains of the progenitors of the

Silurian groups of fossils? For certainly on my theory such strata must somewhere have

been deposited at these ancient and utterly unknown epochs in the world's history.

I can answer these questions and grave objections only on the supposition that the geological

record is far more imperfect than most geologists believe. It cannot be objected that there

has not been time sufficient for any amount of organic change; for the lapse of time has

been so great as to be utterly inappreciable by the human intellect. The number of specimens

in all our museums is absolutely as nothing compared with the countless generations of

countless species which certainly have existed. We should not be able to recognise a species

as the parent of any one or more species if we were to examine them ever so closely, unless

we likewise possessed many of the intermediate links between their past or parent and present

states; and these many links we could hardly ever expect to discover, owing to the imperfection

of the geological record. Numerous existing doubtful forms could be named which are probably

varieties; but who will pretend that in future ages so many fossil links will be discovered,

that naturalists will be able to decide, on the common view, whether or not these doubtful

forms are varieties? As long as most of the links between any two species are unknown,

if any one link or intermediate variety be discovered, it will simply be classed as another

and distinct species. Only a small portion of the world has been geologically explored.

Only organic beings of certain classes can be preserved in a fossil condition, at least

in any great number. Widely ranging species vary most, and varieties are often at first

local, -- both causes rendering the discovery of intermediate links less likely.

It is interesting to contemplate an entangled bank, clothed with many plants of many kinds,

with birds singing on the bushes, with various insects flitting about, and with worms crawling

through the damp earth, and to reflect that these elaborately constructed forms, so different

from each other, and dependent on each other in so complex a manner, have all been produced

by laws acting around us. These laws, taken in the largest sense, being Growth with Reproduction;

inheritance which is almost implied by reproduction; Variability from the indirect and direct action

of the external conditions of life, and from use and disuse; a Ratio of Increase so high

as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing

Divergence of Character and the Extinction of less-improved forms. Thus, from the war

of nature, from famine and death, the most exalted object which we are capable of conceiving,

namely, the production of the higher animals, directly follows. There is grandeur in this

view of life, with its several powers, having been originally breathed into a few forms

or into one; and that, whilst this planet has gone cycling on according to the fixed

law of gravity, from so simple a beginning endless forms most beautiful and most wonderful

have been, and are being, evolved.