A HISTORY OF SCIENCE 



all the cunning and all the force that man is able to 

 exert is necessary to accomplish such unions, even be- 

 tween species that have the nearest resemblances. 

 And when the mule breeds that are thus produced by 

 these forced conjunctions happen to be fruitful, which 

 is seldom the case, this fecundity never continues be- 

 yond a few generations, and would not probably pro- 

 ceed so far without a continuance of the same cares 

 which excited it at first. Thus we never see in a wild 

 state intermediate productions between the hare and 

 the rabbit, between the stag and the doe, or between 

 the marten and the weasel. But the power of man 

 changes this established order, and continues to pro- 

 duce all these intermixtures of which the various 

 species are susceptible, but which they would never 

 produce if left to themselves. 



"The degrees of these variations are proportional to 

 the intensity of the causes that produced them name- 

 ly, the slavery or subjection under which those animals 

 are to man. They do not proceed far in half-domesti- 

 cated species. In the cat, for example, a softer or 

 harsher fur, more brilliant or more varied colors, 

 greater or less size these form the whole extent of 

 variety in the species; the skeleton of the cat of 

 Angora differs in no regular and constant circum- 

 stances from the wild-cat of Europe. 



"The most remarkable effects of the influence of 

 man are produced upon that animal which he has re- 

 duced most completely under subjection. Dogs have 

 been transported by mankind into every part of the 

 world and have submitted their action to his entire 



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