512 



THE AVE, 



'EAL1ST 



[Vol. L 



manns's work and has received no support from the cytological 

 studies of Yamanouchi, Lewis, Kvlin and Svedelius. Oltmanns's 

 view that tetraspores have no fixed place in ontogeny and are 

 without relation to a sporophyte generation has been over- 

 whelmed by the cytological work of the authors mentioned above. 

 And now Svedelius argues that even the old view that cysto- 

 carps represent a sporophytic phase can not be correct for a 

 group of the red algae which he terms haplobiotic. The situation 

 as it now stands may be summarized as follows: An antithetic 

 alternation of generations may be expected wherever tetrasporic 

 plants are found in a life history and in these forms the gonimo- 

 blasts also constitute a phase of the sporophyte. There is no 

 sporophyte in the "haplobiotic" red alga? (e. g., Scinaia with 

 N emotion, Batrachospermum, etc., not yet studied from this 

 standpoint) and the gonimoblasts of these forms represent a 

 haploid development of the zygote in position upon the plant, 

 carpospores being equivalent to monospores. Fusions with auxil- 

 iary cells are merely cytoplasmic in character and associated 

 simply with nutritive functions. The diplobiotic red algae have 

 come from the haplobiotic, which, carrying forward the reduc- 

 tion divisions through the gonimoblasts and carpospores to a new 

 generation, the tetrasporic plants, have established the reduction 

 divisions in the tetrasporangium. In theory these views are 

 simple and logical. For the antithetic alternation of sexual and 

 tetrasporic plants the evidence is considerable and convincing. 

 What will be the conclusions for the "haplobiotic" types? Will 

 future studies establish their existence? 



Bradley Moore Davis 



University of Pennsylvania, 

 July, 1916 



