28 THE FORM OF ANIMALS. 



In any country where a particular race of animals nas 

 continued for centuries, it may be presumed that their 

 constitution is adapted to the food and climate. 



The pliancy of the animal economy is such, as that an 

 animal will gradually accommodate itself to great vicis- 

 situdes in climate and alterations in food ; and by de- 

 grees undergo great changes in constitution ; but these 

 changes can be affected only by degrees, and may often 

 require a greater number of successive generations for 

 their accomplishment. 



It may be proper to improve the form of a native race, 

 out at the same time it may be very injudicious to attempt 

 to enlarge their size. 



The size of animals is commonly adapted to the soil 

 which they iihabit ; where produce is nutritive and abun- 

 dant, the animals are large, having grow^n proportionally 

 to the quantity of food which for generations they have 

 been accustomed to obtain. Where the produce is 

 scanty, the animals are small, being proportioned to the 

 quantity of food which they wTre able to procure. Of 

 these contrasts the sheep of Lincolnshire and of Wales 

 are examples. The sheep of Lincolnshire would starve 

 on the mountains of Wales. 



Crossing, the breed of animals may be attended with 

 bad effects in various ways ; and that, even when adopted 

 m the beginning on a good principle ; for instance, sup- 

 pose some larger ewes than those of the native breed 

 were taken to the mountains of Wales and put to the 

 rams of that country ; if these foreign ewes were fed in 

 proportion to their size, their lambs would be of an im- 

 proved form and larger in size than the native animals ; 

 but tJie males produced by this cross, though of a good 

 form, would be disproportionate in size to the native 

 ewTs; and therefore, if permitted to mix with them, 

 would be proJuctivc of a standing ill-formed prngeny 



