234 



WILLIAM LAWRENCE TOWER. 



parents, and equally dominant. On the contrary, the Chicago 

 stocks showed a rather good rate of survival, about the average, 

 and in that the entire test was in a space not over six feet square, 

 with a uniform sandy soil, the result can hardly be attributed 

 to highly localized differences in the winter conditions. 



In the summer of 1912 further and more extensive tests were 

 made as follows: 

 T 99 in FIO in the second summer generation to Chicago in 



September. 

 T 100 in F 4 in the second summer generation to Chicago in 



September. 

 T 100 A in Fo in the second summer generation to Chicago in 



September. 



The tests for the year comprise the determination of survival 

 in populations that had been at Tucson two, four and ten 

 generations. The results of these tests as determined in the 

 spring of 1913 are given in Table II. 



TABLE II. 



In T 99 no survivals were found, and the survivals from T ioo, 

 although given opportunity to breed, died without issue, and 

 the survivors from T ioo A gave a first summer generation of 

 twenty-six males and thirty-seven females, these a second summer 

 generation of fifty-five males and forty-seven females, of which 

 two males and three females were able to survive hibernation in 

 the following winter, but did not breed after their emergence 

 from hibernation in the spring of 1913. 



In the FI hybrids in this year (1912), regardless of the direction 

 of the cross, all were eliminated in hibernation, not one appear- 

 ing in the following spring, again showing the complete dominance 

 of the Tucson trait over the original or normal condition at 



