THE HOMOSPOROUS LEPTOSPORANGIAT^ 



351 



for a year or more. In O. cinnanwmca they first appeared 

 about two weeks later. While they are almost always present 

 upon the large female prothallia/ numerous exclusively male 

 plants are always met with. These latter are usually irregular 

 in form, and even filamentous, especially wdien crowded. Upon 

 the latter the antheridia are either terminal or marginal ; in the 

 flattened prothallia they occur mainly upon the margin and 



Fig. 194. — A, Prothallium of O. Claytoniana, about two months old, X about 30; B, 

 base of an older prothallium of the same species with a secondary prothallium 

 ipr-) growing from it, X8o; (^, antheridia; C, small branching male prothallium 

 of the same species, X75. 



lower surface of the wings. The development corresponds 

 closely in all forms that have been examined, and differs con- 

 siderably from that of the Polypodiace?e. 



The mother cell is cut off as usual, but the second wall Is 

 not funnel-shaped, but plane and inclined, so that it strikes the 

 basal cell. In the larger of the two cells thus formed a vary- 



^ Luerssen (/. c. p. 449) states that they are often absent from very vig- 

 orous prothallia.^ 



