320 Journal of Agricvltural Research voi. iv. N0.4 



INHERITANCE OF SEX * 



Among more than 6,000 seedlings which have flowered in the New York 

 Experiment Station vineyards, less than 100 pure male vines have been 

 found. Of these there are complete breeding records for 62 vines, 5 1 of 

 which came from crosses in which the pollen parent was a pure male, 

 leaving 11 males recorded as produced by pollen from hermaphrodite 

 plants. Of these, 5 were pure seedlings from one parent, the other 6 from 

 5 crosses. These 6 were probably hermaphrodites erroneously recorded 

 as males, an error very easy to make when the pistil has a short style 

 and one which has been made several times and corrected by subsequent 

 observations. The parent yielding the 5 males was discarded shortly 

 after being used in breeding, and our records are meager. It was prob- 

 ably an intermediate recorded as a hermaphrodite. Such an interme- 

 diate, having both male and hermaphrodite blossoms, is under observa- 

 tion in one of the Station vineyards, and its pollen seems to behave as 

 the pollen of a pure male; in other words, it is reasonable to assume that, 

 excluding these intermediate forms, pollen from hermaphrodite plants 

 will not produce pure males. 



The results obtained from pure males as pollen parents are : 

 Hermaphrodite female X pure male = 



56 hermaphrodites -|- 51 pure males 



Following the assumptions usual to such cases, the hermaphrodite 

 would be considered a sex heterozygote and the male a sex homozygote. 

 Yet selfed hermaphrodites yield only hermaphrodites. These results are 

 similar to those obtained at this Station from selfed hermaphrodite straw- 

 berries, but differ from Shull's results (7) with species of Lychnis, where 

 the hermaphrodite gave both females and hermaphrodites. This condi- 

 tion might be covered by the assumption that the hermaphrodite is a 

 female in which the addition of a single dose of maleness has caused the 

 production of male organs, the ovules keeping the composition 9 9 

 and the pollen becoming ^ 9 : 



Hermaphrodite X hermaphrodite = 99XJ9=2c?9+299 



Since we have no pure females, we must assume that some condition 

 prevents the formation of individuals with the composition 9 9 ; there- 

 fore, the above cross gives only hermaphrodites. Of course, if we do 

 not attempt to assume the method of origin of the hermaphrodite, the 

 case may be covered by considering the hermaphrodites pure for this 

 character, while the males would be heterozygous : 



?$X$5=5$ 



COLOR OF SKIN 



Colors of grapes are not sharply diflferentiated, grading from white 

 through many shades of red and purple to black. Because of this wide 

 range, the problem of finding varieties which are pure for certain colors 



