No. 597] INHERITANCE OF SEX IN THE GRAPE 



In the following discussion the term "female" will 

 refer to the plants bearing morphologically perfect 

 flowers but having reflexed stamens, the pollen of which 

 is not functional. "Hermaphrodite" refers to those 

 bearing perfect flowers, the stamens of which are upright 

 and produce functional pollen. "Male" refers to those 

 plants bearing staminate flowers. 



The expectation from the cross "UxU" (hermaph- 

 rodite FH X hermaphrodite FH) would be 3 hermaph- 

 rodites: 1 female (FF); the hermaphrodites being of 

 two types, viz., 2 FH : 1 HH. This ratio is very closely 

 met in the figures 180 upright and 47 reflexed. "TJ 

 selfed" should give the same proportions and these are 

 closely approached in the figures 673 upright and 152 re- 

 flexed. This assumes the production of homozygous 

 hermaphrodites (HH), which, when either selfed or 

 crossed with other types, produce only hermaphrodites. 

 Apparently the two hermaphrodites which produced 18 

 hermaphroditic seedlings only, when selfed, are of this 

 genetic constitution. At the Minnesota Experiment Sta- 

 tion four hundred seedlings of Beta, open to cross pollina- 

 tion, produced only hermaphroditic flowers; indicating 

 that Beta must be homozygous for the hermaphrodite 

 determiners. 4 



The crosses "R X R " and "R selfed" (female FF X 

 female FF), producing both hermaphrodites and females, 

 might be explained on the hypothesis already given, viz., 

 that of partial suppression of the determiner for male- 

 ness in the chromosome bearing the determiner for 

 femaleness. 



It has already been pointed out that in the pistillate 

 flowers bearing reflexed stamens, a series of pollen condi- 

 tions, ranging from those in which the microspore nucleus 

 does not divide, through those in which the generative 

 nucleus aborts directly after the microspore division, to 

 those in which a few normal functional pollen grams are 



4 In Lychnis dioica Shull has shown that homozygous hermaphrodites are 



