MENDELIAN INHERITANCE IN VARIETAL 

 CROSSES OF BRYONIA DIOICA. 



Bv W. XEILSOX JONES, M.A. and M. (^HEVELY RAYNER, D.Sc. 



The breeding experiments desciilied in tliis papei- were carried ent 

 as a result of observations made on plants of Bri/onia dioica intended 

 originally for experiments bearing im the inheritance of sex. 



It is well kmiwn that species hybrids resulting from the crosses 

 B. dioica x B. alba and B. alba x B. dioica are sterile (1, 2). 



It has, moreover, been suggested that parthenogenesis occurs regu- 

 larly in normal flowers of B. dioica (3, 4). 



Our records agree with those of previous observers as to the sterility 

 of these hybrids, but no experimental proof was obtained by us that 

 parthenogenesis occurs in B. dioica, althougli a large number of flowers 

 weie covered and kept under observation. 



It was thought possible that crosses of the species named with other 

 members of Cucurbitaceae might yield further results, and with this 

 end in view B. dioica and B. alba were used for reciprocal crosst^s with 

 Gihcarhita Melo, Cucurbita Pepo (3 vars.) and Ciicvmif! sutiva. 



These crosses were all unsuccessful. 



In one case, viz. B. dioica x C. Melo, fruit set and several seeds 

 different in shape and colour fi-om those of the seed parent were formed 

 but did not germinate. In no case was viable seed obtained as a result 

 of such species crosses. 



In the course of these and of other experiments for which B. dioica 

 was used, a side issue was raised which led to the breeding experiments 

 described in the present paper. 



The plants in our original cultures of B. dioica were obtained froiri 

 three sources : 



{(i) Wild seedlings froni the Lanibnurne Valley, Berkshire. 



