336 



Zygote 

 Heterozygous 



4 XYWXYW 



5 XYWXYW 



6 XYWXYW 



Douhleness in Stocks 



Gametes 



XYW and XYW 

 XYW and XYW 

 XYW and XYW 



VII. Segregation in F^ cross-breds derived from unions between ever- 

 sporting and non-double-throwing forms, and statement of the results 

 obtained in F^. 



The various possible unions coming under this head are the 

 following : 



Eversporting form employed as seed parent 



A. 

 Mating 



d-cream ? 

 d-non-cream ? 

 d-cream ? 

 d-non-cream ? 

 d-sulphur-white ? 

 d-sulphur- white ? 



X 7io-d-cream <? 



X 7io-d-non- cream <? 



X 7M)-d-non-cream <? 



X 7io-d-cream s 



X no-d-cream <r 



X no-d-non-cream <? 



B. EversiMrting form employed as pollen parent 



Mating 7 

 8 



10 

 11 

 12 



7M)-d-cream ? 

 no-d-non-cream ? 

 no-d-non-cream ? 

 no-d-cream ? 

 no-d-cream ? 



X d-cream <? 



X d-non-cream <? 



X d-cream i 



X d-non-cream <f 



X d-sulphur-white ^ 



no-d-non-cream ? x d-solphur- white i 



In the case of matings 7 — 12 where the eversporting form is used 

 as the pollen parent we may expect every F^ family to yield doubles in 

 F^, whereas in the reciprocal unions (matings 1 — 6) some of the Fi 

 individuals may be expected to yield doubles and some to breed true 

 to singleness. Reference to Tables IV and V will show that such 

 was the case in each of the 8 types of union which have already been 

 carried out. 



With regard to the proportion of doubles occurring in those F^ 

 families which are mixed, it has been stated in the earlier accounts' 

 that they occur in the proportion of the simple Mendelian recessive, 



^ loc. cit. 



