E. R. Saunders 341 



Mating 8. 7io-d-non-crea.m $ x c?-non-cieam (f. 



The expectation in this case is that all F^ plants will yield 

 a mixture of singies and doubles in F.^. 



A few experiments of this kind are given in the Evolution Reports, 

 and others have been carried out since (see Table IV). The results in 

 both cases are summarised below : 



Parental Types 



' no-(i-glabrous flesh ? x d-glabrous dark purple J 



' no-d-glabrous white ? x d-glabrous copper <s 



' ,, „ i X d-glabrou8 red <f 



., „ ? X „ <? 



?io-(J-hoary white (Brompton) $ x ,, d 



no-(f-glabrous flesh s x (J-hoary white (intermediate) d' - 



„ „ ? X d-glabrous light purple J 



Totals 60 60 



Altogether 60 F-^ plants were self-fertilised and all gave a mixture of 

 singles and doubles in F„. In the great majority of the families the ratio 

 approximated to 3 s. : 1 d., in fact, in all but the last mating it can 

 hardly be doubted that this represents the real ratio. If we take the 

 case where the largest number of F^ plants were bred from (as likely to 

 furnish the most reliable result), and sum all the families (46) together, 

 we get a total of 1640 s. and 505 d., where 1609 s. and 536 d. would 

 have been an exact result. In the case of the mating between wo-rf-fiesh 

 and d-light purple however there is a very large deficiency of doubles in 

 certain families, and it is evident that here some further complication 

 is present. The question that arises is, whether this result is due to 

 the particular constitution of one of the two parents, or whether it is 

 the result of a combination of factors, some of which are brought in by 

 the one parent, some by the other. This point is not easy to determine ; 

 ■ on the whole, however, the evidence may be taken to point to the latter 

 alternative, other factors being concerned besides X and Y in the 

 manner suggested above (p. 338). The conclusions indicated by the 

 series of results bearing on the point may be put thus : 



1. The ?io-d-glabrous flesh individual used as seed parent in the 

 union with d-Wghi purple did not happen to be employed in any other 



1 Eecorded in Eeport II, p. 37. 

 '^ See note, p. 326. 

 Journ. of Gen. i 23 



