3Z 



nSCUSSION OF RESTTLTS . 



Prom the cytological evidence brouglit forward in this 

 paper it seems probable that there exists in Grif fithsia 

 Borne ti ana an alternation of generations similar to that 

 which has been suggested for Polysipiionia violacea (YAil- 

 A2T01TCITI , '06). The fusion nucleus, which contains 14 

 chromosomes, with the cooperation of the c^rtoplasm of some 

 of the cells of the procarp, produces the ci'stocarp, in 

 which are formed carpospores; the nucleus of each of these 

 contains 14 cliromosomes . The nuclei of the tetraspoTic 

 plant contain each 14 chromosomes; and it therefore seems 

 reasonable to assume that the tetrasporic plaints arise from 

 carpospores. In the first division of the nucleus of the 

 tetraspore mother cell, the number of cliromosomes is re- 

 duced one -half, so that 7 chromosomes enter the nucleus of 

 each tetraspore. It seems probable that on germinating, 

 the tetraspore gives rise to an individual, whose general 

 morphological relations and vegatative structure are sim- 

 ilar to those of the plant producing tetrasjores, with t\/o 

 significant exceptions, (1) the nuclei show at mitosis 7 

 chromosomes instead of 14, and (2) the individual bears 

 sexual organs instead of asexual spores. In other words, 

 in r^rif fithsia a sexual plant is probably succeeded by an 



