l92 On Elucidating the Natural Hixtory of Man 



easy. All the modifications, so varied, so complex, and, in ap- 

 pearance, so unintelligible, which these latter present, are the 

 same modifications which wild animals exhibit, only produced 

 on a more extensive scale ; the same causes which produce the 

 former produce also the latter, although they are increased both 

 in number and in intensity. 



Unless a wild variety exists at one and the same time in po- 

 sitions which are very different as to their elevation, and conse- 

 quently as to their temperature and atmospheric pressure, an event 

 which but rarely happens ; and unless it is also found widely dis- 

 tributed in some places which are very arid, and in others which 

 are very It^-mid, a coincidence perhaps rarer still, we must, ere we 

 can find a species with marked differences, necessarily take for the 

 terms of our comparison, individuals which belong to regions 

 which are widely separated from each other. But this possibihty is 

 itself included within a determinate and generally a very narrow 

 circle. The geographical distribution of each being is vigorous- 

 ly fixed by its necessities and requirements ; wherever local cir- 

 cumstances which are very different, might lead to important 

 modifications in the organization of a species, and especially be- 

 cause it is so, there, that species is no longer to be found ; be- 

 cause, free to range at will, it wanders where circumstances are 

 favourable to it, that is to say, to those locahties which, agreeing 

 with the requirements of its organization, tend to preserve its 

 type, and not to modify it by a powerful, and on that very ac- 

 count, a very troublesome reaction. 



The conditions of variation are very different in domesticated 

 animals. In the first place, very marked modifications are ob- 

 served without a proportionate difference in the region they in- 

 habit ; for the omnipotence of man, acting variously on the 

 animals which are subjected to him, creates for them in the same 

 region local circumstances which are entirely dissimilar. In the 

 second place, the number and the intensity of modifying influ- 

 ences become, so to speak, illimitable, for we no longer have for 

 any domestic breed either determinate nourishment, habits, or 

 climate, and as often as the will of man acts upon them in a 

 different way so often ai-e they placed under new causes of varia- 

 tion. 



Thus, precisely and for the same reasons, we find so many 



