194 Plant Genetics 



with the theory. Other plants are prevailmgly male but 

 bear a few weak female flowers, and inbreeding in this 

 case results in loo per cent males. Finally, there are oc- 

 casional plants which are evenly monoecious; that is, half 

 of their flowers are strong males and the other half strong 

 females. From inbreeding such a plant, the resulting 

 progeny is 50 per cent male and 50 per cent female. It 

 is obvious that from such results Strasburger would be 

 convinced of his theory of male and female tendencies. 



Such a theory involves too much of Riddle's quanti- 

 tative idea to be acceptable to cytologists. They seem 

 confident that sex determiners will be demonstrated 

 eventually as distinct physical entities and that such 

 phrases as "male and female tendencies" will disappear. 



It will be interesting to apply Strasburger's theory 

 to cases of parthenogenesis and vegetative apogamy and 

 discover the difficulties encountered. In the first place, 

 in monoecious forms it is found that a parthenogenetic 

 egg produces a monoecious plant. Should it not produce 

 a strictly female plant, because eggs contain only 

 female tendencies ? Strasburger avoids this difficulty 

 by saying that these parthenogenetic eggs are diploid; 

 hence they are not truly eggs but merely sporophyte 

 cells. The process of producing the new plant, therefore, 

 is merely vegetative multiplication, which would natu- 

 rally perpetuate the tendencies of the parent body. The 

 parent was monoecious, and quite properly the progeny 

 of a diploid egg should be monoecious. 



Strasburger used this same situation to confirm 

 his theory. In dioecious forms parthenogenetic eggs 

 should produce only female plants. As a matter of fact 

 this is true, as Strasburger shows by a number of 



