THE HOMOSPOROUS LEPTOSPORANGIATJE 



373 



of some of the larger Mosses, e. g., species of Mnium. Hooker 

 ( i ) reduces them all to three genera, which, however, are often 

 further divided. Of these Loxsoma is represented by but one 

 species, L. Cunninghaniii, a form which seems to be intermedi- 

 ate in general characters between the Cyatheacese and the other 

 Hymenophyllaceae, but its life history and anatomy are not 

 known. Of the other genera Hooker gives seventy-one species 

 to Hymenophyllum and seventy-eight to Trichomanes. 1 



The Gametophyte 



The gametophyte is known more or less completely in sev- 

 eral species of both Trichomanes and Hymenophyllum. The 



A. 



r. 



FIG. 214. Trichomanes Draytonianum. Germination of the spores, XS25; r, primary 



rhizoid. 



large spores germinate promptly, but their subsequent develop- 

 ment is very slow. They contain chlorophyll and often begin 

 to germinate within the sporangium, where they may often be 

 found divided into three equal cells by walls radiating from the 

 centre (Fig. 214). All of the cells begin to grow out into 

 filaments, but usually only one of them develops into the pro- 

 thallium, the others dividing only once or twice, and forming 

 short brown rhizoids. In some species of Trichomanes, e. g. 



1 The number of species known now considerably exceeds this. 



