ALLEN— SEX INHERITANCE IN SPH^ROCARPOS. 



295 



two of the four spores of a tetrad develop into female plants and 

 the other two into male plants. In 9 cases of 81 studied, more 

 than four plants were present in a single group ; but on the assump- 

 tion that two tetrads had germinated in close proximity, these cases 

 were brought into harmony with the rule. In only four instances 

 of the 81 the distribution of sexes was "abnormal" (5 females and 

 3 males, i female and 3 males, and in two cases 3 females and i 

 male). The plants thus studied by Douin apparently included rep- 

 resentatives of both 6". Michelii and S. texanus. The evidence thus 

 furnished was cited by Strasburger (1909) as proof that in Sphccro- 



FiG. 9. A female plant of Sphccrocarpos Domicilii from a greenhouse 

 culture; sporophytes are present within the swollen bases of several of the 

 involucres, as at s, s, X 7- Fig. 10. A portion of a similar plant in vertical 

 section showing the relation of the sporophytes (s, s) to the structures of 

 the gametophyte. X 7- Fig. ii. A group of four spores, resulting from the 

 division of a single spore mother cell and remaining permanently attached. 

 X 312. Drawings by Miss Martha Engel. 



carpos the sex tendencies, brought together in the union of &gg and 

 antherozoid and remaining united, thoi:gh of course not finding ex- 

 pression, during the life of the sporophyte, are separated by the 



