x THE HOMOSPOROUS LEPTOSPORANGIATJE 351 



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

 about two weeks later. While they are almost always present 

 upon the large female prothallia, 1 numerous exclusively male 

 plants are always met with. ^ These latter are usually irregular 

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

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

 flattened prothallia they occur mainly upon the margin and 



A 



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 

 (pr 2 ) 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 Polypodiacese. 



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- 



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

 orous prothallia, u 



