| I
here
give a
sketch of the progress of opinion on the Origin of Species.
→The
great majority of naturalists
that species
immutable productions, and
been separately created. This view has been ably maintained by many authors. Some few naturalists, on the other hand,
that species undergo modification, and that the existing forms of life
→have descended
by true generation
pre-existing forms. Passing over
→authors from
the classical
→period to that of Buffon, with whose writings I am not familiar,
↑
was the first man whose conclusions on
subject excited much attention. This justly-celebrated
first published his views in
much enlarged them in 1809 in his 'Philosophie Zoologique,' and subsequently, in 1815, in
Introduction to his
Nat. des Animaux sans
In these
→works
he upholds the doctrine that all species, including man, are descended from other species. He first did the eminent service of arousing attention to the probability of all change in the
as well as in the inorganic
being the result of law, and not of miraculous interposition. Lamarck seems to have been chiefly led to his conclusion on the gradual change of species, by the difficulty of distinguishing species and varieties, by the almost perfect
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
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
to progress, in order to account for the existence at the present day of
simple productions, he
that such forms
now spontaneously
generated.
∗ |
