THEORY OF THE EARTH. 107 



of each species is susceptible ; and from them de- 

 rives productions which the species, if left to 

 themselves, would never have yielded. 



Here the degree of the variations is still pro- 

 portional to the intensity of their cause, which is 

 slavery. It is not very high in the semi-doines- 

 ticated species, such as the cat. A softer fur ; 

 more brilliant colours ; greater or less size ; these 

 form the whole extent of the variations in this 

 species ; for the skeleton of an Angora cat dif- 

 fers in no regular and constant circumstance from 

 that of a wild cat. 



In the domesticated herbivorous animals, 

 which we transport into all kinds of climates, and 

 subject to all kinds of management, both with re- 

 gard to labour and nourishment, we certainly ob- 

 tain greater variations ; but still they are all 

 merely superficial. Greater or less size ; longer 

 or shorter horns, or even the want of these entire- 

 ly ; a hump of fat, larger or smaller, on the 

 shoulder ; these form the differences between the 

 various races of the common ox or bull ; and these 

 differences continue long, even in such breeds as 

 have been transported from the countries in 

 which they were produced, when proper care is 

 taken to prevent crossing. 



Of this nature are also the innumerable varie- 

 ties of the common sheep, which consist chiefly 

 in differences of their fleeces, as the wool which 



