6 Britton andT/.ylor: Life History of Schizaea pusilla 



sides, but maintain the same relative position (Fig. 30). The 

 branches, which give rise to the spherical cells to be described 

 below, divide in the same manner as the main filaments. The 

 division of other blanches is very irregular (Figs. 29, 30, 31). 

 The rhizoids are not usually formed directly from the ordinary 

 cells, but from specially modified cells (Fig. 38,0); in three in- 

 stances only were rhizoids found directly on the filaments, and in 

 one case one cell gave rise to two rhizoids. They arise as lateral 

 branches, at right angles to the long axis of the filament and tak- 



ing the place of branches (Figs. 38, 39). There were two cases 

 found (Figs. 32, 33) where the cells of a branch, near the apex, 

 had formed partition walls. In Fig. 32 the third cell from the 

 apex had divided up into four cells, showing a tendency to form a 

 flat prothallus. Three cells showed signs of division (Fig. 33): 

 these two instances were the only ones found. Bower speaks of 

 flattened expansions on the filamentous protonema of Trichomanes 

 alatitm and Trichomanes sinuosiim as described by Mettenius. 

 These are much more rudimentary in Schizaea pusilla. 



Some cells of the filament have been found to undergo division 

 in the later stages, into a number of disk-shaped cells which do 

 not increase in the axial diameter. Constrictions sometimes follow 

 such divisions at the older cross walls ; the cell walls were a light 

 brown and showed signs of decay. Fig. 3 5 shows the cells of the 

 filament undergoing the same process, but these were as healthy 

 as the rest of the filament and densely filled with chlorophyl. 

 Bovver refers (Ann. Bot. i: //. /. /. 8) to a similar develop- 



pyxidift 



* * possibly the 



moniliform development is merely a pathological condition ; its 

 appearance, however, is suggestive of that segmentation of the 

 protonema into spherical cells which is recorded as a mode of vege- 

 tative propagation for the protonema of Fun aria hygrometrica." 



After some of the filaments have formed several cells the apical 

 cell cuts off a new cell, which, after the first partition wall, that 

 is transverse septum, divides longitudinally, forming two cells 

 (Figs. 36, 37). These cells become large and round, each cell 

 containing chlorophyl, and giving rise to one, or generally two, 

 rhizoids (Fig. 37, a). The rhizoids also contain chlorophyl and 

 early take on a dark yellow color. The original cell of the fila- 



