XI 



THE HOMOSPOROUS LEPTOSPORANGIAT^ 



343 



centimetres. He also records a genuine dichotomy of the older 

 prothallia of this species. 



The AntJieridiuni 



Under favourable circumstances the first antheridia appear 

 after about a month in O. Claytoniana, and continue to form for 



Fig. 172. — A, Prothallium of O. Clciytoniana, about two months old, X about 30 ; B, base of an 

 older prothallium of the same species with a secondary prothallium (;>?-2) growing from it, X 80 ; 

 c5, antheridia ; C, small branching male prothallium of the same species, X75. 



a year or more. In 6^. cinnamomea 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 when crowded. Upon the 

 latter the antheridia are either terminal or marginal ; in the 

 flattened prothallia they occur mainly upon the margin and 



^ Luerssen {I.e. p. 449) states that they are often absent from very vigorous 

 prothallia. 



