LAMARCK’S THEORY OF DESCENT 323 
all the inhabitable regions of the globe, each species 
has received, through the influence of circumstances to 
which it has been exposed, the habits which we have 
observed, and the modifications in its organs which 
observation has shown us it possesses. 
“The first of these two conclusions is that believed 
up to the present day—namely, that held by nearly 
every one; it implies, in each animal, an unchanging 
organization and parts which have never varied, and 
which will never vary ; it implies also that the circum- 
stances of the places which each species of animal 
inhabits will never vary in these localities ; for should 
they vary, the same animals could not live there, and 
the possibility of discovering similar forms elsewhere, 
and of transporting them there, would be forbidden. 
“The second conclusion is my own: it implies that, 
owing to the influence of circumstances on habits, 
and as the result of that of habits on the condition 
of the parts and even on that of the organization, 
each animal may receive in its parts and its organiza- 
tion, modifications susceptible of becoming very con- 
siderable, and of giving rise to the condition in which 
we find all animals. 
“To maintain that this second conclusion is un- 
founded, it is necessary at first to prove that each 
point of the surface of the globe never varies in its 
nature, its aspect, its situation whether elevated or 
depressed, its climate, etc., etc.; and likewise to 
prove that any part of animals does not undergo, even 
at the end of a long period, any modification by 
changes of circumstances, and by the necessity which 
directs them to another kind of life and action than 
that which is habitual to them. 
“ Moreover, if a single fact shows that an animal 
for a long time under domestication differs from the 
wild form from which it has descended, and if in such 
a species in domesticity we find a great difference in 
conformation between the individuals submitted to 
