134 



Isabel McCracken. 



Table XI shows results of S X S matings from both S c? X B 9 

 and B c? X S 9 parentage, while Table XII shows results of B X B 

 matings from the same parents. 



The data in these tables add to the evidence of previous tables 

 that B behaves like a Mendelian recessive, reproducing its kind, 

 while S behaves like a Mendelian dominant, reproducing both its 

 own kind, S, and the recessive, B. 



Table XII— B X B. 



At date of writing, the available material for the fifth generation 

 matings is very much reduced, being confined to fifteen B broods 

 pure bred for four generations and five S broods pure bred for 

 the sarrie length of time. These have shown no tendency to mate, 

 and it is hoped that they will hibernate and form a nucleus for 

 next year's work; failing this, the experiment will be continued 

 with the first outdoor individuals to appear in the spring. 



