XIV] 



THE FILAMENTOUS TYPE 



279 



Goebel, I.e. p. 957). Nevertheless the allied genera Anemia, Mohria, and 

 LygodiiLui possess essentially typical flattened prothalli. The filaments con- 

 sist of rows of chlorophyll-containing cells, having the general habit of a 

 Cladophora. Some of these run horizontally along the surface of the sub- 

 stratum, and are attached by brown rhizoids formed in regular relation to 

 distended spherical cells (Fig. 269, A (S)). The latter are inhabited by fungal 

 filaments, which extend onwards into the rhizoids, the whole structure being 

 clearly a mycorhizic coalition. From their position it seems probable that 

 the spherical cells represent branches of the filamentous thallus specialised 

 for this method of nutrition. Other brantrhes roughly alternating with them 

 may grow upwards from the substratum, branching repeatedly, and func- 



Fig. 269. ^ =prothallus of Schizaea pusilla, bearing spherical cells {S) with endophytic fungal fila- 

 ments. ar=:archegonia; a« =: antheridia. ^ = segmentation of an antheridium of i'f/i2S(Tmr///«/rw: 

 the lid is not always divided. C, Z> = mature antheridium and archegonium of Schizaea pusilla. 

 A, C, D, after Britton and Taylor. B, after von Goebel. 



tionally photo-synthetic. They bear also the sexual organs, both of which 

 may be present on the same thallus. They occur singly. The antheridia {a7i) 

 correspond in position to branches of the filament, springing like them from 

 the upper end of the cell that bears them. Each antheridium represents the 

 ending of a dwarf-branch. The isolated archegonia occupy a similar position, 

 but are seated as a rule on small masses of cells resulting from longitudinal 

 division of the cells at the base of a filament {D). As von Goebel remarks, 

 " In such free archegonia we see undoubtedly the simplest state in any of 

 the Pteridophyta." The archegoniophore is here in its simplest form. It is 

 a tenable position that ScJiizaea illustrates a really primitive state of the 

 gametophyte. 



