1906] YAMANOUCHI—POLYSIPHONIA VIOLACEA 433 
4. Tetraspore formation terminates the sporophytic phase with 
typical reduction phenomena, so that the tetraspores are prepared to 
develop the gametophytic generation. 
5. There is thus an alternation of sexual plants (gametophytes) 
with tetrasporic plants (sporophytes) in the life history of Polysiphonia, 
and the cystocarp forms a part of the sporophytic phase. 
THE UNIVERSITY OF CHICAGO. 
