VIRILE SENTIMENT 73 



of the grandparents had duplex eyes. This is quite 

 in accordance with the theory of gametic purity 

 and segregation, and it is altogether discordant 

 with any other theory of inheritance, whether bio- 

 metrical (mathematical) or otherwise. 



Turning now to the results when both parents 

 are duplex, we have just seen that three combinations 

 are possible. Of these, the two combinations 

 D D X D D and D D x D R will give the same 

 visible result, i.e., all the offspring will show the 

 duplex type of eye. But the third combination, 

 i.e., D R X D R, will give a mixed offspring, in the 

 proportion of three individuals having duplex eyes 

 { =1 D D + 2 D R) to one having the simplex eyes. 

 Examining Mr. Hurst's results, we find that our 

 expectations are fulfilled, for of the fifty pairs of 

 parents which he recorded, both of whom had duplex 

 eyes, thirty-seven of them had a total offspring, one 

 hundred and ninety-five in number, all with duplex 

 eyes. They, therefore, illustrate the two first com- 

 binations. The remaining thirteen parents had a 

 mixed offspring, of a total number of sixty-three 

 individuals. Forty-five of these showed the duplex 

 eyes, and eighteen of them the simplex eyes. In 

 nearest round numbers the expectation is forty-seven 

 and sixteen respectively. That is, Mendelian pre- 

 diction and result are practically identical. 



The next possible combination will be between 

 parents having duplex eyes and those with simplex 

 eyes. But the duplex parent may be one of 

 two things — either a, D D oi Si D R. So that from 



