y48 Proceedings of the Ohio State Academy of Science 



plants two microspores of a tetrad will give rise to male gameto- 

 phytes with sperms which in fertilizing the egg are prepotent 

 over the female tendency and so will produce staminate plants ; 

 the other two microspores will give rise to gametophytes whose 

 sperms are not able to overcome the female tendency of the egg 

 and hence will produce carpellate plants. 



Correns supports his hypothesis by results obtained through 

 studies of Bryonia dioica and other plants. He believes that the 

 egg always carries the same sex tendency, namely to produce 

 females are more properly speaking carpellate plants, while the 

 sperms are of two kinds, half bearing the female and half the 

 male (staminate) tendency. The male tendency dominates over 

 the female. The females are therefore, homozygous (female 

 -\- female) with respect to sex; the male are heterozygous 

 (female -|- male) with respect to sex. In other words, the 

 female is a homozygous recessive while the male is a heterozy- 

 gous dominant. But if the observations on bees are correct, 

 then the egg must have the male tendency ; for all parthenogene- 

 tic developments among the common honey bees result in males. 



According to Castle, the female is the male condition plus 

 something else, i. e. a distinct unit character Mendelian in hered- 

 ity. Maleness is not, then, the jMendelian allelomorph to fe- 

 maleness, but a differential factor between male and female is 

 allelomorphic to absence of that factor. Presence of the factor 

 then means femaleness, absence of it means maleness. The dif- 

 ferential factor is supposed to be inherited as a Mendelian char- 

 acter dominant over its absence. But it must be remembered 

 that both sexes develop peculiarities absent in the other and the 

 male has usually more than the female. The sex determination 

 simply causes one or the other set of peculiarities to appear. 



Castle concludes among other things that sex is not directly 

 controlled by the environment but is determined by internal 

 (gametic) factors. But this does not harmonize with the facts 

 presented by the homosporous and heterosporous pteridophyte 

 gametophytes. Castle's further statement that the determina- 

 tion of sex depends upon the presence in the zygote of a factor 

 or factors which are inherited in accordance with Mendel's law 



