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 Uves 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 of a 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 



