o his work on "The Origin of Species"; and the most important
extracts of Lamarck's "_Philosophie Zoologique_" are to be found in Oscar
Schmidt's "Descent and Darwinism."[1]

Sec. 2. _Indirect Preparations._

While thus the ideas of Lamarck gradually fell into partial oblivion, yet
contemporaneous with and following them arose several other series of
thoughts, views, and investigations, which, although they only indirectly
prepared for the revival of the evolution theory, yet exercised a deeper
and more lasting influence on the minds of scientists. We refer to the
ideas in regard to natural phenomena held during the first decades of our
century; further, to the principles of comparative anatomy which, up to the
present time, partly dependent {34} and partly independent of natural
philosophy, have been expressed, valued, and admired as leading thoughts;
and, lastly, to the empiric results of comparative anatomical and
biological investigations in palaeontology and geology, as attained by the
help of those very principles. And even physics and astronomy had to
cooeperate in preparing the way for the idea of evolution.

The philosophical ideas referred to, together with the points of view and
results of comparative anatomy, led more and more decisively to the idea of
an _original form_, or _type_, which retains its identity in all the
modifications of form in plants and animals; and of a _ground-plan_, which
is realized in the systems of the plant and animal world in higher and
higher differentiations and in more and more developed modifications,
diverging farther and farther from the prototype until it reaches its
highest form, still reducible to the prototypes, in the most highly
organized dicotyledons in plants, and in the animal world in the mammalia,
and lastly in man.

Men like Cuvier and Geoffrey St. Hilaire, who otherwise stand diametrically
opposed to each other, unite in these and kindred ideas. The naturalist
Oken attains the same result, tinged with the views of Schelling; the poet
Goethe, from an intuitive knowledge of nature, arrived at the same
conclusion. The former, during a journey in the Hartz Mountains, at the
sight of a bleached deer's skull, and the latter, upon picking up a sheep's
skull in the Jewish cemetery at Venice, were struck by the same thought:
the skull is only a modified vertebra. Oken founded upon this idea and
kindred analogies his profound philosophy of the system of animals and
plan