ANIMALS MADE USEFUL 17 
proving both plants and animals. The law of heredity is 
the basis of breeding success. Its structural principle 
is “like begets like.” Heredity holds, keeps and guards 
the values of the best fitted animals. 
“I would not miss the opportunity to drive home the jdea that 
frequently the parent can only be sized up by observing the off- 
spring. A parent frequently transmits qualities it does itself not 
seem to have, at least not to be observed.”—Landacre. 
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* 
Just Like PEAS IN A PoD 
Note the striking resemblance of the pigs one to another and to the mother. Here 
is demonstrated the fundamental law of heredity, or ‘‘like begets like.” 
' 9. Variation—Opposed to heredity is the law of 
variation. This force seeks to produce new things ; hered- 
ity preserves uniformity. Variation is the law of change; 
heredity is satisfied with what exists. Variation goes 
out to explore, to seek new paths and new fields. An 
animal breeder builds upon present heredity, but he 
courts variation and urges it to seek new findings. If 
these are to his liking, he seizes them as his own, attaches 
