9^ 



covery by YAJ^^rOUCHI that the dividing nuclei of the tet- 

 raspore-producing plant tiiroughout its iiistory, as well as 

 those of the sporogenous cells of the cystocarp, show 40 

 chromosomes (t}ie 2x niuaher) , while the nuclei of the sexual 

 plants show 20 chromosomes (the x nvunber) . The nvunber of 

 the chromosomes is reduced in the divisions of the nucleus 

 of the tetr^spore mother cell; the double niuaber is Restor- 

 ed by the union of the nuclei of the gamates. In discuss- 

 ing the origin of the tetraspore, YALJ'jTOUCPII surmises that 

 in some such form as Batracnospermma , in which monospores 

 are borne along v.itli gamates on the sexual plants, reduction 

 !nay ha,ve 'been suppressed in the formation of the carpos- 

 pore, "so that it germinates with the sporophytic nujober of 

 chiTomo somes, producing a plant v;^hich consequently becomes 

 at once a part of the sporophytic phase. It is quite pos- 

 sible that the first tetraspore mother cell corresponded to 

 monospores on the sexual plant except that they had tlie 

 double niuaber of chromosomes, since such reproductive cells 

 v<ould very naturally become the seat of the delayed reduc- 

 tion phenomena,. The resejiiblance in general morphology of 

 the tetrasporic plants in the red algae to the sexual 

 plants would be expected, because they live under similar 

 environmental conditions" (b.435) , 



