THE HOMOSPOROUS LEPTOSPORANGIATAi 



353 



as in the Hepaticse, and the mature spermatozoids arc coiled 

 more flatly than in the Polypodiaceae. The free spermatozcjid 

 recalls that of Marattia or Equisettim rather than that of the 

 Polypodiaceae. There are but about two complete coils, and 

 the hinder one relatively larger than in the latter forms. In 

 swimming there is peculiar undulating movement, suggestive 

 of the spermatozoid of Equisctiim. 



The Archcgonium 

 The archegonia are only borne upon the large heart-shaped 



OpOO 

 Uo 



Fig. 196. — A, Ripe antheridium of O. Claytoniana, just ready to open; B, the same 

 discharging the sperm cells, X600; C, two spermatozoids, X1200; o, operculum. 



prothallia, and occupy the sides of the projecting midrib, where, 

 if the earlier ones are not fertilised, they may continue to form 

 indefinitely ; but no correspondence can be made out between 

 them and the initial cells, and while developed for the most part 

 in acropetal order, new ones may arise among the older ones. 



