250 SANSOME 



coming infected with Ustilago violacea and developing anthers. 

 As a rule the anthers also become infected with the fungus, and 

 therefore cannot be used for breeding. Eriophyid mites cause 

 sex reversal in species of Salix (Harrison). 



In the case of the genetic hermaphrodites, Belar and Heitz 

 have shown one series to have the XY complex of chromosomes, 

 and the Hertwigs have given genetic results which agree with 

 the view that they are males with a modification of the gene 

 complex on the X chromosome. Akerland has found herma- 

 phrodites of the same species with the female complex XX 

 chromosome in both anthers and ovaries. 



Attempts to reverse the sex of Melandrium plants have been 

 made without success. I have grafted males and females to- 

 gether, ovariotomised with hot needles, injected pulped anthers 

 and have used cultural methods. The sex types of Aucuba 

 japonica (Sansome) and of Mercurialis annua (Yampolsky) also 

 are not changed by intergrafting. 



Empetrum nigrum has the XY chromosome complement in 

 the male and XX in the female. Empetrum hermaphroditum, is 

 tetraploid and hermaphrodite with XXYY. The two XX and 

 two YY disjoin at meiosis in such a way that all gametes get one 

 X and one Y (Hagerup, 1929). 



Again, Ono and Shimotomai found a triploid Rumex acetosa 

 with 18 chromosomes + XX + YY. The plant was intersexual. 

 The diploid male plants of the same species have the constitu- 

 tion 12 + X + 2Y, and the diploid female 12 + 2X. A triploid 

 female had the constitution 18 + XXX + YY. These polybasic 

 forms are amenable to interpretation along the lines suggested 

 by Bridges for intersexes in Drosophila. 



The distribution of sub-dioecious species throughout the 

 plant kingdom is also irregular. In these species one sex type 

 is pure, while the alternative type is predominantly and 

 functionally female or male with a greater or less development 

 of male- or female-like organs respectively. Such species are 

 Silene Rmmeri (Correns), Silene Otites (Newton), Valeriana 

 dioica (Correns), Huniulus japonica and lupulus, Fragaria 

 elatior, Cirsium arvense (Correns), Urtica dioica, Mercurialis 

 annua (Yampolsky). 



In these species, with the exception of Urtica dioica and 

 Mercurialis annua where the female is sub-gynoecious, the 



