the weaker organisms down. The thistle, which has
spread over the Pampas, to the destruction of native plants, has been
more effectually "selected" by the unconscious operation of natural
conditions than if a thousand agriculturists had spent their time in
sowing it.

It is one of Mr. Darwin's many great services to Biological science
that he has demonstrated the significance of these facts. He has shown
that--given variation and given change of conditions--the inevitable
result is the exercise of such an influence upon organisms that one
is helped and another is impeded; one tends to predominate, another
to disappear; and thus the living world bears within itself, and is
surrounded by, impulses towards incessant change.

But the truths just stated are as certain as any other physical laws,
quite independently of the truth, or falsehood, of the hypothesis
which Mr. Darwin has based upon them; and that M. Flourens, missing the
substance and grasping at a shadow, should be blind to the admirable
exposition of them, which Mr. Darwin has given, and see nothing there
but a "derniere erreur du dernier siecle "--a personification of
Nature--leads us indeed to cry with him: "O lucidite! O solidite de
l'esprit Francais, que devenez-vous?"

M. Flourens has, in fact, utterly failed to comprehend the first
principles of the doctrine which he assails so rudely. His objections to
details are of the old sort, so battered and hackneyed on this side of
the Channel, that not even a Quarterly Reviewer could be induced to pick
them up for the purpose of pelting Mr. Darwin over again. We have Cuvier
and the mummies; M. Roulin and the domesticated animals of America; the
difficulties presented by hybridism and by Palaeontology; Darwinism a
'rifacciamento' of De Maillet and Lamarck; Darwinism a system without a
commencement, and its author bound to believe in M. Pouchet, etc. etc.
How one knows it all by heart, and with what relief one reads at p. 65--

"Je laisse M. Darwin!"

But we cannot leave M. Flourens without calling our readers' attention
to his wonderful tenth chapter, "De la Preexistence des Germes et de
l'Epigenese," which opens thus:--

"Spontaneous generation is only a chimaera. This point established, two
hypotheses remain: that of 'pre-existence' and that of 'epigenesis'.
The one of these hypotheses has as little foundation as the other." (P.
163.)

"The doctrine of 'epigenesis' is derived from Harvey: following by
ocu