THE HOMOSPOROUS LEPTOSPORANGIATjE 



353 



as in the Hepaticae, and the mature spermatozoids are coiled 

 more flatly than in the Polypodiacea^. The free spermatozoid 

 recalls that of Marattia or Equisctum rather than that of the 

 Polypodiace^e. 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 Equisctum. 



The Archegonium 

 The archegonia are only borne upon the large heart-shaped 



Q-. 



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. 



prothalHa, 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. 

 23 



