CONTROL OF HEREDITY: EUGENICS 373 



believable differences in structure and dispo- 

 sition; or by the great variety of domestic 

 fowls, all of which have probably descended 

 from the wild jungle-fowl; or by modern races 

 of horses, cattle, sheep, or swine. These are 

 only a few of the many illustrations which 

 could be cited of the practical control of he- 

 redity and evolution for human purposes. 

 How have the present races of domesticated 

 animals and cultivated plants been produced? 



FIG. 88. Wild Boar contrasted with a modern domestic 

 Pig. (From Romanes.) 



