4 Brixton and Taylor : Life History of Schizaea pusilla 



apex. On August 30th the chlorophyl showed a tendency to as- 

 sume its final arrangement in the filament, being very dense in the 

 center, radiating toward the walls in rather thick bands and con- 

 necting with a layer next to the wall through the whole length of 

 the cell ; on August 31st the filament had lengthened to 126// 

 and one more cell had been cut off (Fig. 21), no further change 

 in the rhizoid having taken place. The filament consisted of five 

 cells by September 2d. On September 4th the filament had in- 

 creased to six cells, and a partial division of the contents of the 

 apical cell had taken place (Fig. 22). The tip of the filament 

 was very much curved and densely packed with chlorophyl ; the 

 basal cell of the filament had become slightly swollen near its 

 apical end. The filament measured 146 //. 



On September 5th the filament consisted of six cells (Fig. 23) ; 

 the first walls formed were very nearly as thick as the cross-walls 

 of the older filaments. 



The older filaments generally grow erect, and this tendency 

 toward an upward growth is plainly shown even as early as the 

 third cell of the filament ; the rhizoid also showed geotropic curva- 

 ture. One tube, issuing from the fissure of an exospore, was di- 

 rected downward ; but soon began a curvature which was continued 

 until the filament occupied a vertical position ; the rhizoid, first 

 directed horizontally, soon curved downward. The filaments, for 

 the most part, did not show the tendency to upward growth until 

 two or three cells had been formed, but the rhizoid took a down- 

 ward direction much earlier. 



On September 5th another spore was found in the soil consist- 

 ing of one filament of six cells (Fig. 24) ; at the base of the fila- 

 ment, at its connection with the spore, there was a cell which had 

 evidently been the basal cell of another filament. The remaining 

 filament had given rise to two antheridia, which though not dried 

 up were empty ; one antheridium arose from a short branch from 

 the second cell, occupying the terminal cell of the branch ; the 

 other originated from the terminal cell of the filament. 



A spore with a healthy filament of four cells (Fig. 26) had borne 

 an antheridium in which the mother cells of the antherozoids could 

 be easily seen. 



The attachment of the spore appears to be of long duration, as 

 antheridia are formed while the filament is still attached. 



