Monoecism and Intersexuality 451 



ordinates of the developmental system — their interpretation is always 

 the same in principle. All these facts may, in addition, be used as 

 material to support the correctness of our interpretation of sex in 

 Melandrium. 



MONOECISM AND 

 INTERSEXUALITY 



a. Introduction 



In our discussion of Melandrium we used the terms "subandroe- 

 cious," "subgynoecious," and "intersexual" in the same sense without 

 much explanation. When we analyze sex determination in animals and 

 flowering plants in terms of identical genetic ideas, we must, however, 

 realize the differences. Correns used the term "euhermaphrodites," 

 for example, for a Melandrium species or race or experimental product 

 in which both female and male organs are functional. When we 

 considered before such conditions, produced by the presence of four 

 X-chromosomes, it could be described as one step in the change from 

 maleness to femaleness, that is, intersexuality. But if we use such a 

 term, we must realize that it means something different from inter- 

 sexuality, say, in Lymantria or Drosophila. In the monoecious flower, 

 whether it is primarily monoecious or secondarily by a sexual shift 

 away from a male (or a female, if found), there are two spatially 

 separated anlagen for complete male and female organs, both of 

 which can be evoked alone or simultaneously and become functional 

 together. This situation is then comparable in animals to a genuine 

 hermaphrodite like a trematode with two complete functional and 

 spatially separated sex organs. The trematode parallels Melandrium 

 so far as all members of the order are hermaphrodites except one 

 genus, Schistosomum. My student, Lindner (1914), could show that 

 this exception involves the establishment of a 2X-1X mechanism. This 



