LAMARCK’S THEORY OF DESCENT 299 
change has been wrought in the state of their parts 
compared with that of animals of the race from which 
they have descended. 
“ Who does not know that such a native bird, which 
we raise in a cage and which lives there five or six 
years in succession, and after that replaced in nature— 
namely, set free—is then unable to fly like its fellows 
which have always been free? The slight change of 
circumstance operating on this individual has only 
diminished its power of flight, and doubtless has not 
produced any change in the shape of its parts. But 
if a numerous series of generations of individuals of 
the same race should have been kept in captivity for 
a considerable time, there is no doubt but that even 
the form of the parts of these individuals would 
gradually undergo notable changes. For a much 
stronger reason, if, instead ofa simple captivity con- 
stantly maintained over them, this circumstance had 
been at the same time accompanied by a change to 
a very different climate, and if these individuals by 
degrees had been habituated to other kinds of food, 
and to other kinds of movements to obtain it; cer- 
tainly these circumstances, united and becoming con- 
stant, would insensibly form a new and special race. 
“Where do we find, in nature, this multitude of 
races of dogs, which, as the result of domesticity to 
which we have reduced these animals, have been 
brought into their present condition? Where do 
we find these bull-dogs, greyhounds, water spaniels, 
spaniels, pug-dogs, etc., etc., races which present 
among themselves much greater differences than 
those which we admit to be specific in wild animals 
of the same genus? 
“ Without doubt, a primitive single race, very near 
the wolf, if it is not itself the true type, has been sub- 
mitted by man, at some period, to the process of 
domestication. This race, which then offered no dif- 
ference between its individuals, has been gradually 
