162 



cell (Fig. 1So). From the prothallial tissue which adjoins 

 the sperm cells are cut off flattened cells (Fig 64?/^ 

 which invest the sperm cells with a more or less definite 

 layer of "mantle cells". The limits of the original cover cell 

 are usually plainly visible in both longitudinal and surface 

 sections (Figs. 77—78). 



The material of (). moluccayium was not abundant enough 

 to make a study of the living spermatozoids possible, and 

 in 0. })endulum , although repeated efforts were made to 

 secure the opening of the antheridium and the discharge 

 or the spermatozoids, they were all unseccessful, and just 

 what the conditions are that are necessary for this must 

 remain for the present unsettled. Apparently the develop- 

 ment of the antheridium is excessively slow, and this 

 perhaps accounts for the fact that none of the specimens 

 selected for experiment seemed to have the stages ready for 

 dehiscence. There is no reason to suppose that the method of 

 dehiscence differs materially from that described by Bruchmann 

 for 0. vulgatiim. (loc. cit. p. 238). As in the latter species the 

 opening is effected by the destruction of the triangular cell, which 

 often, before opening, shows a discolored appearance — especially 

 conspicuous in material fixed with the Flemming solution. The 

 empty antheridium, in longitudinal section, shows the destroyed 

 opercular cell very plainly, and the strongly projecting „mantle 

 cells" surrounding the emply cavity. In no cases seen by the 

 writer was the chambered appearance, due to the persistence 

 of some of the primary cell walls such as is sometimes found 

 in Botrychium, observed. (See Mossks & Feuns, 2d edit.. Fig. 128). 



While the writer was unsuccessful in obtaining free sper- 

 matozoids, it was possible neverthelese to make a very satis- 

 factory study of the spermatogenesis, for which Ophioglossum 

 is especially suited, owing to the very large size of the sper- 

 matozoids. The spermatozoids of 0. pendulum are probably the 

 largest known among the Pteridophytes. 0. moluccanum proved 

 especially good for the purpose, but the small number of an- 

 theridia available made it impossible to secure all the stages. 



