/ 



Britton and Taylor : Life History of Schizaea pusilla 7 



ment from which these cells arise either continues its growth 

 normally (Fig. 36), or by a lateral innovation (Fig. 37). This new 

 filament, after the formation of two or three cells, may form spher- 

 ical cells at its apex (Fig. 39), or continue for some time before 

 doing so, or it may send off a branch at once, which in its turn 

 forms spherical cells. Generally a filament forming the spherical 

 cells once does so at intervals throughout its whole length (Figs. 

 72, J2))' These branches early bend to the substratum. If ex- 

 amined at this stage they will be found to have lost their former 

 contents and to be filled with fungal hyphae (Fig. 43). This fungus 

 does not injure its host, but sets up a symbiotic connection by 

 which it functions as an absorbing organ to supply the gameto- 

 phyte. So the spherical cells are undoubtedly formed by the 

 gametophyte for the reception of the fungus, which enters as soon 

 as the rhizoids touch the substratum (Fig. 41). While above 

 ground and filled with chlorophyl they do not show any evidence 

 of the presence of a fungus. The rhizoids wither early and ab- 

 sorption is carried on almost entirely by the fungal hyphae. The 

 lack of rhizoids on the filament is thus explained by the presence 

 of this fungus symbiont. The rhizoids formed from these spherical 

 bodies appear to be the only channels through which the fungus 

 enters the chambers built for it. 



As to the nature of the fungus it is at present impossible to 

 give it a permanent place in any of the series because of lack of 

 evidence in regard to its method of reproduction. Perithecia 

 have been found with asci and also what was probably a conidial 

 stage ; fruit bodies of other forms have also been found among the 

 filaments ; however, none of these were connected with the fungal 

 hyphae under discussion. The young filament shortly after ger- 

 mination was in some few cases attacked by a fungus (Fig. 17, d\ 

 and this fungus is found wrapped around many of the cells of the 

 older filaments, several instances having been found where haus- 

 toria had penetrated into the cells. Some of the plants are so in- 

 fected by fungi after the growth of the sporophyte has begun that 

 all the filaments have thickened walls and are pierced by three 

 or four haustoria in each cell ; they have turned brown and lost 

 their contents. This fungus not only clings to the gametophyte 

 of Schizaea pusilla but attacks the sporophyte also, though it does 



