324 LAMARCK, HIS LIFE AND WORK 
such habits and those restricted to different habits, 
then it will be certain that the first conclusion does 
not conform to the laws of nature, and that, on the 
contrary, the second is perfectly in accord with them. 
“Everything combines then to prove my asser- 
tion—namely, that it is not the form, either of the 
body or of its parts, which gives rise to habits, and 
to the mode of life among animals; but that it is on 
the contrary the habits, the manner of living, and all 
the other influencing circumstances which have, after 
a time, constituted the form of the body and of the 
parts of animals. With the new forms, new faculties 
have been acquired, and gradually nature has come 
to form the animals as we actually see them. 
“Can there be in natural history a consideration 
more important, and to which we should give more 
attention, than that which I have just stated ? 
“We will end this first part with the principles and 
the exposition of the natural classification of animals.” 
In the fourth chapter of the third part (vol. ii. pp. 
276-301) Lamarck treats of the internal feelings of 
certain animals, which provoke wants (dcsozus). This 
is the subject which has elicited so much adverse criti- 
cism and ridicule, and has in many cases led to the 
wholesale rejection of all of Lamarck’s views. It is 
generally assumed or stated by Lamarck’s critics, who 
evidently did not read his book carefully, that while 
he claimed that the plants were evolved by the direct 
action of the physical factors, that in the case of all 
the animals the process was indirect. But this is not 
correct. He evidently, as we shall see, places the 
lowest animals, those without (or what he supposed 
to be without) a nervous system, in the same category 
as the plants. He distinctly states at the outset that 
