372 



FERNS 



new fern plant is soon formed. The young plant remains 

 attached to the prothallium and gains nourishment from 



Figure 400. — a, Position of Sori ; b, Section of Sorus. 



4 



it. As soon as the young fern is able to get nourishment 

 by its own roots, it begins life as an independent plant 

 and the prothallium dies. There is the same alternation 

 of generations in the fern that occurs in the mosses, the 



5pores 



Prothallium 



■Protonema 



New Fern 



Figure 401. — Life History of Fern. 



prothallium being the gametophyte and the "fern' 1 the 

 sporophyte, but the latter is the longer lived and much 

 the larger plant (Figure 401). 



