XI 



THE HOMOSPOROUS LEPTOSPORANGIATA-l 



361 



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

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



Yic \Z(i. — Tricho]na7ies D7-aytoniaiiuiu (Brack). Germination of the spores, X 525 ; r, primary 



rhizoid. 



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

 T. pyxidiferiun} the prothallium remains filamentous, and 

 forms a densely branching structure very much like the 



...s 



Fig. 187. — HymenophyllujH (sp). A, Large prothallium of the natural size ; B, part of the margin of 

 one of the growing branches, showing two similar initial cells, X180; C, a filamentous male 

 prothallium derived from a bud, x6o. 



protonema of some Mosses, but coarser in texture. Other 

 species, however, e.g. T. alatuni, produced flattened thalloid 



1 Bower (8). 



