No. 597] INHERITANCE OF SEX IN THE GRAPE 555 



the hermaphrodite and female determiners, and showing 

 further that in the sweet pea only one dose of maleness 

 is necessary for the production of functional stamens. 



Similarly in many animals, it has been proved by 

 Wilson, Morgan and others that the males are hetero- 

 zygous for the sex determiner and the females homo- 

 zygous, and that this condition is correlated with the pres- 

 ence of two chromosomes in the female which are distinct 

 from the others and which they called the "X" bodies, 

 while in the male only one may be present, or if there are 

 two, the second is sometimes smaller and is spoken of as 

 the " Y" body. Occasionally the X and Y bodies may be 

 of equal size and the supposition that they are different 

 is based upon inheritance studies. 



The reverse of the above mentioned condition may 

 exist, as in Abraxis, pigeons, cultivated fowl, etc., in 

 which the males are apparently homozygous for the sex 

 determiner and the females heterozygous. 



Strasburger found that in Bryonia there were two 

 chromosomes which were larger than the others and 

 thought that these might carry the determiners for sex. 



A great deal of evidence has recently been collected 

 which points to the chromosomes as being the carriers of 

 factors and as many factors have been shown to be linked 

 with sex, it seems safe to conclude that certain chromo- 

 somes carry the determiner for sex. If this is the case, 

 then in the hermaphroditic plants it must be assumed 

 that the determiners for maleness and femaleness are 

 linked or carried in the same chromosome; otherwise 

 there would continually be produced not only hermaph- 

 rodites but staminate and pistillate plants as well. 



The trend of development in many plant groups seems 

 to be toward the production of a diecious condition by the 

 suppression of the stamens in one set of individuals and 

 of the pistils in another. As an instance of this may be 

 cited the strawberry, in which staminate, pistillate and 

 perfect flowers are produced. The grape and maple and 

 many other plants show a like suppression in varying 

 degrees. 



