134 THE MENDEL JOURNAL 



intelligible statement of the probable processes at 

 work, it is not altogether free from objection. The 

 assumption of the undifferentiated nature of both 

 the pollen and egg-cells of B. alba, with the further 

 necessary assumption that these have a com- 

 position different from those of B. dioica, is one 

 that would require a great deal of evidence in its 

 favour before we should be justified in finally ac- 

 cepting it. 



But there is a simpler interpretation which quite 

 as adequately fits the facts and does not involve 

 the serious assumption necessitated by Correns' 

 theory. It is the interpretation of Professor Bateson. 

 In his scheme we regard not the male, but the female, 

 as being dominant. The pollen-cells of B. dioica are 

 regarded as homozygous carrying maleness alone, 

 while the pollen-cells of B. alba are also regarded as 

 homozygous but carrying femaleness alone. The 

 female or egg-cells of both species are regarded as 

 heterozygous. Individuals of both species will possess 

 two kinds of egg-cells, and these will occur in ap- 

 proximately equal numbers. One half of them will 

 carry maleness and the other half femaleness. We 

 shall then expect that when the egg-cells of B. dioica 

 are fertilised with the pollen-cells of the same species, 

 there will be produced equal numbers of male and 

 female offspring. For when a pollen-cell which carries 

 maleness meets an egg-cell which, as we have 

 postulated, carries maleness alone, clearly the 

 resulting offspring from such a fertilisation must be 

 male. But when the second kind of egg-cell, that 



