XI 



THE HOMOSFOROUS LEFT0SP0RANGIA'1\E 



365 



followed, and whether there is any division of the neck canal 

 cell is not known. The neck is straight, as in Osmunda and 

 GleicJienia. 



In TricJwiiianes the archegonial meristem (archegoniophore) 

 may be formed as a short branch, directly upon the filamentous 

 prothallium. 



The lateral walls of the prothallial cells are in all the forms 

 thicker than is the case in most Ferns, and there are distinct pits 

 in them. In the root-hairs a parasitic fungus is frequently found. 



Fig. 190. — Pinna of the leaf of HyviefiophyUum 7-ccunniin (Gaud.), X 3 ; B, part of rhizome (r) and 

 leaf of Trichomams fiarvuhiin (Poir.), X3; C, pinna of the leaf of Trichomancs cyrtotJicca 

 (Hilleb.), X3; D i, trumpet-shaped indusium of the same, X4; 2, section of the indusium (id) 

 with the central sorus, x 5 ; j, the sorus. 



The embryogeny is almost unknown,^ but the first divisions 

 and the very young sporophyte correspond closely with those of 

 the other Leptosporangiatai. The cotyledon is simple with a 

 single median vein, and a root is present in all forms yet 

 examined. 



TJie Mature Sporophyte 



Prantl "" has given a very complete account of the structure 

 of the mature sporophyte, and Bower ''' has added to this by a 

 careful study of the meristems of the different organs. From 



^ Janczewski (2) 



- Prantl (i). 



Bower (il). 



