HERMAPHRODITISM 171 



of the cells by being left at the dividing line between 

 the two cells. We can understand how two kinds 

 of individuals are produced by the hermaphrodites 

 from the two classes of sperm combining at random 

 with the eggs. 



These two kinds of individuals are females with 

 twelve chromosomes, and males with eleven chromo- 

 somes. How then can we get back to the hermaph- 

 roditic generation ? Boveri and Schleip suggest that 

 the males again produce two kinds of spermatozoa, — - 

 they have shown this to be the case in fact, — and that 

 the male-producing spermatozoa become function- 

 less. Here we have at least an outline of some of 

 the events in the life cycle of this worm in relation 

 to the chromosomes, but no explanation of hermaph- 

 roditism. 



Turning to plants, there are the interesting experi- 

 ments of the Marchals with mosses. They show that 

 the sporophyte is hermaphroditic and has the factors 

 for maleness and femaleness combined as a result 

 of fertilization ; while in the formation of the spores 

 the factors in question are separated. 



Blakeslee has found somewhat similar relations in 

 certain of the molds. The spores in molds contain 

 more than one nucleus, therefore it is not clear how 

 segregation in the sense used for other cases applies 

 here. 



In the flowering plants that are hermaphroditic 

 we have Correns' experiments, in which he crossed an 

 hermaphroditic type of Bryonia alba with a type 

 B. dioica in which the sexes are separate. The 

 cross when made one way gives only females, while 



