of
species, by the difficulty of distinguishing species and varieties,
by the almost perfect gradation of forms in certain groups, and by
the analogy of domestic productions. With respect to the means of
modification, he attributed something to the direct action of the
physical conditions of life, something to the crossing of already
existing forms, and much to use and disuse, that is, to the effects of
habit. To this latter agency he seems to attribute all the beautiful
adaptations in nature; such as the long neck of the giraffe for
browsing on the branches of trees. But he likewise believed in a law
of progressive development, and as all the forms of life thus tend to
progress, in order to account for the existence at the present day of
simple productions, he maintains that such forms are now spontaneously
generated. (I have taken the date of the first publication of Lamarck
from Isidore Geoffroy Saint-Hilaire's ("Hist. Nat. Generale", tom. ii.
page 405, 1859) excellent history of opinion on this subject. In
this work a full account is given of Buffon's conclusions on the same
subject. It is curious how largely my grandfather, Dr. Erasmus Darwin,
anticipated the views and erroneous grounds of opinion of Lamarck in
his "Zoonomia" (vol. i. pages 500-510), published in 1794. According to
Isid. Geoffroy there is no doubt that Goethe was an extreme partisan of
similar views, as shown in the introduction to a work written in 1794
and 1795, but not published till long afterward; he has pointedly
remarked ("Goethe als Naturforscher", von Dr. Karl Meding, s. 34) that
the future question for naturalists will be how, for instance, cattle
got their horns and not for what they are used. It is rather a singular
instance of the manner in which similar views arise at about the same
time, that Goethe in Germany, Dr. Darwin in England, and Geoffroy
Saint-Hilaire (as we shall immediately see) in France, came to the same
conclusion on the origin of species, in the years 1794-5.)

Geoffroy Saint-Hilaire, as is stated in his "Life", written by his
son, suspected, as early as 1795, that what we call species are various
degenerations of the same type. It was not until 1828 that he published
his conviction that the same forms have not been perpetuated since
the origin of all things. Geoffroy seems to have relied chiefly on the
conditions of life, or the "monde ambiant" as the cause of change. He
was cautious in drawing conclusions, and did n