12 PRINCIPLES OF STOCK-BREEDING. 



The nervous system and mental condition, the 

 organs of nutrition and reproduction, the habits, pre- 

 dispositions, and temperament, the bones, the muscles, 

 and the powers of endurance, that characterize the 

 parents, are all reproduced in the offspring without 

 essential change in their characteristics. 



Illustrations, drawn from the different departments 

 of organic life, will serve to show the extent and per- 

 sistent action of the law of heredity, and aid us in de- 

 termining its applications in the breeding of domestic 

 animals. 



In the geological formations, representing immense 

 periods of time, fossil species and generic forms pre- 

 sent the same essential characters throughout their 

 entire range. 



The various species of wild animals are readily 

 recognized wherever found, and the lapse of time 

 represented in the historic period has made no appre- 

 ciable change in their characters. The animals that 

 have been preserved in the monuments of Egypt for 

 thousands of years are essentially the same as those 

 now found on the borders of the Nile. 1 



So far as the art of breeding is concerned, a con- 

 sideration of the various theories of evolution can be 

 of no practical value, and the observed repetition of 

 generic and specific forms may be assumed to repre- 

 sent a constancy in the inherited characteristics of 

 animals. 



The cycle of changes through which the embryo 

 passes in the process of development remains the 



1 Colin, "Physiologic Compare," tome ii., p. 533; Darwin's "Ani- 

 mals and Plants under Domestication," vol. i., pp. 30-60. 



