No. 504] NOTES AND LITERATURE 



821 



as the female parent (the hermaphrodite flowers were castrated) 

 and Melandrium as the male parent. All the seed from this 

 cross was sterile. 



Numerous experiments with phylogenetic transition forms 

 ("polyams") between hermaphrodite and monoecious flowering 

 plants on the one hand and hermaphrodite and dioecious forms 

 on the other, i. e., andromoncecious, trimoncecious and gyno- 

 monoecious forms— also with androdicecious, trioecious and gyno- 

 diceeious forms — yielded results less definite, it is true, but never- 

 theless confirmatory (especially as regards the female tendency 

 of the egg-cells of the female plant) of those obtained from 

 hybridization experiments between the end forms as in Bryonia 

 Melandrium and Silene. 



The main results may be summarized under three heads: (1) 

 The germ-cells of female individuals all have the tendency to 

 develop into female plants ; one half of the germ-cells of the male 

 individuals have the tendency to develop into male plants and 

 one half into female. (2) The definitive sex-determination 

 occurs at fertilization; the original tendency of the female germ- 

 cells can be altered through the sex-tendency of the male germ- 

 cells. (3) When at fertilization germ-cells of unlike sex-tend- 

 ency unite, the male tendency dominates over the female. 



The experiments seem to indicate that sex is inherited. 

 Strictly speaking, however, one can not say that a plant has 

 " inherited" sex, but only that the germ-cells have inherited sex- 

 tendencies. Only the anlagen of sex are transmitted from gen- 

 eration to generation, not the characters ("Merkmale") — the 

 cloak that they have woven for themselves (Naegeli). 



Had the hybrids of Bryonia, and those between Melandrium 

 album and Silene viscosa not been sterile, they would undoubt- 

 edly have split up in such a way that the anlage of diceciousness 

 would have been again separated from that of monoeciousness 

 and of hermaphroditism, respectively, and the second generation 

 of these dioecious hybrids would have included pure dioecious, 

 hybrid dioecious and pure monoecious (or hermaphrodite) indi- 

 viduals in the Mendelian proportion of 1:2:1. It remains a 

 question whether the dioecious plants would all have had the sex 

 of the dioecious parent or if both male and female plants would 

 have appeared. 



In all cases in which the offspring are divided approximately 

 equal in respect to sex, and where the eggs show no external 



