BIOMETRY 375 



more or less of the blue color and markings of the wild rock pigeon 

 from which domestic pigeons are presumably descended. He described 

 many cases of dogs, cattle and swine, as well as many cultivated 

 plants, in which offspring resembled distant ancestors and differed 

 from nearer ones; such cases had long been known and were spoken 

 of as '' reversion." He observed many cases in which certain charac- 

 ters of one parent prevailed over corresponding characters of the 

 other parent in the offspring, this being known as ''prepotency"; 

 but there was no satisfactory explanation of these curious phenomena. 

 They did not come under either of Galton's laws, and their occur- 

 rence was apparently so irregular that every such case seemed to be 

 a law unto itself. 



