72 MANUAL OF FARM ANIMALS 



ditions might result in a reversal of the type. In other words, 

 if one wished to enlarge the Shetland ponies all he need do is to 

 feed them abundance of nutritious feed and unite the largest to 

 the largest in breeding and in time they would no longer be 

 known for their small size. On the other hand, if one wishes to 

 retain the small size of the pony, or to diminish it still farther, 

 all that need be done is to restrict the food and unite the smallest 

 to the smallest in breeding. The same is true of any character 

 one wishes to propagate. From this it can be readily observed 

 that we have two forces operating. The first is that like tends 

 to produce like, and the second that if any improvement is 

 brought about, it is through variation. 



VARIATION IS THE BASIS OF IMPROVEMENT 



If characters were absolutely fixed and unchangeable, then no 

 improvement could be secured. The size of the pony could 

 neither be increased nor diminished and the milk flow of cattle 

 would remain constant from generation to generation, and the 

 offspring would be no better than the parent. Variation, then, 

 is the basis of improvement among farm animals. 



Variation universal among farm animals. — No two animals 

 are alike. To those unfamiliar with swine, each pig of a litter 

 may look exactly like the others, yet the trained eye readily 

 recognizes differences and can describe each so that those with 

 equal training may recognize them. These differences extend to 

 all characters. Two cows of the same breed may differ widely 

 in the richness of their milk ; two steers of like breeding differ 

 widely in their ability to fatten and the beef may also differ, 

 the loin of one being fine and tender while the other may be 

 coarse in grain. Of two sheep of the same breed, one may 

 possess wool of bright luster, fine crimp, and even throughout; 

 the other may have wool rather coarse, no crimp, and dift'er 

 much in various parts of the body. There is free variation 

 among living things. 



