the _Annales du Museum d'Hist. nat._, IV^e cahier. 1., 1802,
pp. 302, 303: _Memoires sur les Fossiles des Environs de Paris_, etc. He
repeats in his _Discours_ what he wrote in 1802 in the _Annales_.

[175] _Ibid._ This is repeated from the article in the _Annales_.

[176] _Ibid._ "See my _Recherches sur les Corps vivans_" (Appendix,
p. 141).

[177] _Discours d'Ouverture du Cours des Animaux sans Vertebres,
prononce dans le Museum d'Histoire naturelle en mai 1806._ (No imprint.
8^o, pp. 108.) Only the most important passages are here translated.

[178] "We know that all the forms of organs compared to the uses of
these same organs are always perfectly adapted. But there is a common
error in this connection, since it is thought that the forms of organs
have caused their functions (_en ont amene l'emploi_), whereas it is
easy to demonstrate by observation that it is the uses (_usages_) which
have given origin to the forms of organs."

CHAPTER XVII

THE "PHILOSOPHIE ZOOLOGIQUE"

Lamarck's mature views on the theory of descent comprise a portion of
his celebrated _Philosophie zoologique_. We will let him tell the story
of creation by natural causes so far as possible in his own words.

In the _avertissement_, or preface, he says that his experience has led
him to realize that a body of precepts and of principles relating to the
study of animals and even applicable to other parts of the natural
sciences would now be useful, our knowledge of zooelogical facts having,
for about thirty years, made considerable progress.

After referring to the differences in structure and faculties
characterizing animals of different groups, he proceeds to outline his
theory, and begins by asking:

"How, indeed, can I consider the singular modification in the
structure of animals, as we glance over the series from the most
perfect to the least perfect, without asking how we can account for
a fact so positive and so remarkable--a fact attested to me by so
many proofs? Should I not think that nature has successively
produced the different living beings by proceeding from the most
simple to the most compound; because in ascending the animal scale
from the most imperfect up to the most perfect, the organization
perfects itself and becomes gradually complicated in a most
remarkable way?"

This leads him to consider what is life, and he remarks (p. xv.) that it
does not exist without external stimuli. The cond