468 



BOTANICAL GAZETTE 



[DECEMBER 



divides, giving rise to two cells, the upper one of which becomes a 

 zoospore mother cell, and the lower remains as a stalk cell (figs. 148, 

 149). The process occurs in a number of superficial cells lying 

 side by side, and as a consequence zoospore mother cells are pro- 

 duced in great numbers, lying close together and parallel. When 

 the superficial layers are double, the cells in the outer layer elongate 



Fig. 12. — Aglaozonia re plans: portion of a thallus with numerous filaments; the 

 filament usually consists of two cells, but in the present exceptional case they are 

 made up of a varying number of cells (3-7), and their terminal cells are zoospore 

 mother cells. 



d directly become the mother cells (fi 



Not 



be 



slender 



filament 



mother c 

 ordinary 



terminal 



The zoospore mother cell is at first like an 

 cell, with length and breadth about equal 



