366 



ROSCOE R. HYDE 



Extracted Truncates 



Original Truncates 



41 I 



Extracted Truncates 



da. 9 

 Oriqinal Truncates 



ua.9 



34.6 

 exists between truncates 



and 



Diagram F Showing incompatibilitj^ that 

 extracted truncates (extracted from truncate d^). 



Diagram G Showing incompatibility that exists between truiicates and ex- 

 tracted truncates (extracted from truncate &). 



together was only 47.8. Diagram D shows practically the same 

 condition. 



As just stated the extracted trmicates produce 81.7 goiDd eggs and 

 85. 1 good sperm (diagram C) . We know from many former experi- 

 ments that the truncates produce about 80 per cent of good sperm 

 and 55 per cent of good eggs. Yet when these gametes are brought 

 together, as shown in diagrams A and B there is a marked degree of 

 incompatibility. Diagrams F and G based on this and former 

 experiments, will show at a glance the facts that relate to incom- 

 patibility in this case. 



It remains to be pomted out that there is a rise in fertility beyond 

 that shown by either parent when the truncates extracted from the 

 truncate grandfather B are crossed with the truncates extracted 

 from the truncate grandmother A (diagram E). It seems strange 

 that there should result a rise in fertility in this cross and also when 

 the extracted truncates are back-crossed into their high-producing 

 grandparental stock (diagrams C and D); and yet there results 

 no rise in fertility when the extracted truncate female is back- 



