fixes, pour chaque espece, tant qu'elle se perpetue au milieu des memes
circonstances: ils se modifient, si les circonstances ambiantes viennent a
changer. En resume, L'OBSERVATION des animaux sauvages demontre deja la
variabilite LIMITEE des especes. Les EXPERIENCES sur les animaux sauvages
devenus domestiques, et sur les animaux domestiques redevenus sauvages, la
demontrent plus clairment encore. Ces memes experiences prouvent, de plus,
que les differences produites peuvent etre de VALEUR GENERIQUE." In his
"Hist. Nat. Generale" (tom. ii, page 430, 1859) he amplifies analogous
conclusions.

>From a circular lately issued it appears that Dr. Freke, in 1851 ("Dublin
Medical Press", page 322), propounded the doctrine that all organic beings
have descended from one primordial form. His grounds of belief and
treatment of the subject are wholly different from mine; but as Dr. Freke
has now (1861) published his Essay on the "Origin of Species by means of
Organic Affinity", the difficult attempt to give any idea of his views
would be superfluous on my part.

Mr. Herbert Spencer, in an Essay (originally published in the "Leader",
March, 1852, and republished in his "Essays", in 1858), has contrasted the
theories of the Creation and the Development of organic beings with
remarkable skill and force. He argues from the analogy of domestic
productions, from the changes which the embryos of many species undergo,
from the difficulty of distinguishing species and varieties, and from the
principle of general gradation, that species have been modified; and he
attributes the modification to the change of circumstances. The author
(1855) has also treated Psychology on the principle of the necessary
acquirement of each mental power and capacity by gradation.

In 1852 M. Naudin, a distinguished botanist, expressly stated, in an