Y. TANAKA. 



repulsion are not fundamentally different phenomena, but they are dependent 

 on the manner in which the 'presence' characters, A and B for instance, are 

 brought into the cross. A coupling occurs when A and B are brought in 

 by the same parent, but a repulsion takes place when they come from 

 different parents. 



As to the process which gives rise to the assumed partial gametic series, 

 Bateson and Punxett put forth a suggestion (1911,b) that the case may be 

 easily understood if we suppose as multiple reduplication of certain gametic 

 forms (AB and ab in coupling, Ab and aB in repulsion) effected in the 

 gametogenesis. 



Collins maintains the possibility of the ocvnnvnee of intermediate irametie 

 series such as 2 : 1, 4 : 1, 5 : I, 6 : 1, etc., besides tho.se assumed by 

 Bateson and others, i. e. f 3 : 1, 7 : 1, 15 : 1, 63 : 1, and so forth. 



Baur suggests not only the occurrence of some intermediate systems, but 

 also possible existence of n : 1 : 1 : x series, in which x is greater than n. 



VIII. General Discussion and Conclusion. 



In the foregoing pages, I have described six cases of repulsion and 

 coupling observed in the Silkworm. All of them occurred between the 

 yellow colour of the cocoon and the marking characters of the larva, except 

 a single case of repulsion which took place between two marking factors. 

 These cases may be summarized as follows : 



1) Complete repulsion between Normal marking and Yellow colour. 



2) Complete repulsion between Striped marking and Yellow colour. 



3) Complete rqwhion between Striped marking and Xonnal marking. 



4) Partial coupling between Moricaud marking and Yellow colour. 



5) Partial coupling between Strijml marking and Yellow colour. 



6) Comjilefe coupling between Striped marking and Yellow colour. 



The evidence for the occurrence of these reduplicated systems rests, in 

 some of these cases, upon the result of a single mating, but in others it rests 



