140 



Sex Segregatio7i in the Bryophyta 



hermaphrodite and 5 female, a result which shows a striking preponder- 

 ance of male axes. No sporogonia were borne upon any of the aposporous 

 products as the sex organs were sterile. Abnormal organs of mixed sex 

 also were found in B. caespiticium and Mnium ho7'num. The investigators 

 concluded that there was cause to think that the uni-sexuality of dioicous 

 mosses in the haploid phase was absolute, and due to the presence — to 

 the exclusion of the other — of only one sex determinant, and that the 



2n Sporogonium ^ (Sporoph/te) ^ 



(Antherldium d Antherozoid) n i 



y spore 



"•■ Protonema (/») ? 



Diagrammatic Life Cycle of Dioicous Type. 



^2n Sporogonium $ (Sporophyte) 



i:'spores{n) 



'^ Protonema (/?) ^ 



Diagrammatic Life Cycle of Monoicous Type. 



maturation process was the occasion of the segregation to the state of 

 purity of sexual characters in the spores. In other words a clean cut 

 sex segregation occurred at the reduction division of sporogenesis. Un- 

 doubtedly the low proportion of hermaphrodite axes resulting from 

 aposporously developed protonemata • is a serious hindrance to the ac- 

 ceptance of the theory, for on the hypothesis we should have expected 

 that plants arising aposporously from sporogonial tissues would all be 



