Feb., 1918J Sexual Dimorphism 117 



mal plants usually showed not more than five to seven leaf 

 nodes, while plants raised in poor soil during the summer 

 showed as high as twenty nodes. The staminate plant was 

 dying of old age when photographed, although less than four 

 months old. In plants like the hemp, the sexual dimorphism is 

 as great if not greater than in the ordinary mammals. In fact, 

 in many mammals it is much more difficult to recognize the 

 sexes by somatic characters. 



Among these hemp plants there were intermediates as is 

 common in most diecious species. Staminate plants with more 

 or less carpellate expression were considerably longer lived and 

 more robust than those which were purely staminate. Not 

 only did typical staminate plants sometimes produce bispor- 

 angiate flowers with more or less normal gynecia but some 

 carpellate plants even 43roduced stamens. This in spite of the 

 fact that the plants were differentiated in their vegetative parts 

 as typically carpellate. In plants grown later, out of doors, 

 from the same seed no abnormalities were seen, but as the 

 plants were not examined when they first began to bloom they 

 may nevertheless have been present. The great abundance of 

 intermediates in the winter, greenhouse plants was probably 

 due to the abnormal environment, mainly a lack of light. The 

 point to be emphasized in this connection is that we have here 

 a diecious plant which shows sexual dimorphism even in its 

 remote vegetative parts, but numerous individuals which are 

 thus specialized have the ability to produce the opposite primary 

 sexual generation and sexual cells, without any manipulation 

 whatever being employed, except that they were grown in an 

 unusual environment. How extremely impossible it would be 

 in this case to claim that the specific sex characters were due 

 to sexual Mendelian units, one individual being homozygous 

 for sex and the other heterozygous. The whole behavior in 

 these diecious plants is essentially the same as the sexual dif- 

 ferentiation in the less extreme cases, traced above from Marsilea 

 to Indian-corn. The maleness and femaleness represent states 

 which inhibit to a greater or less degree the development of the 

 opposite organs the heredity of which is potentially present, 

 since both the staminate and carpellate plants do produce both 

 male and female gametophytes. Dieciousness is a differential 

 state, hereditary, of course, in the ordinary sense, which permits 



