56 



CONFERVOIDES. 



of the cells takes place in quite a peculiar and unusual manner. 

 At the upper end of the cell which is about to divide, a ring-shaped 

 thickening of soft cellulose is formed transversely round the wall ; 

 the cell-nucleus of the mother-cell and the protoplasm then divide 

 by a transverse wall into two portions of similar size, and the 



cell-wall bursts trans- 

 versely along the cen- 

 tral line of the thick- 

 ened ring. The cell- 

 wall thus divides into 

 two parts the upper 

 one short, the "cap," 

 and the lower one 

 much longer, the 

 "sheath." The por- 

 tions of the original 



J 



cell-wall now separate 

 from each other, the 

 cellulose ring extend- 





 K\ \/ /12IKI an a dditional length 

 [mP) ^p\ I JBH of cell- wall between 



them. The cap and 

 sheath will project a 

 little in front of the 

 piece thus inserted. 

 The dividing- wall be- 

 tween the two new 

 cells is formed near to 

 the uppermost edge 

 of the sheath, and 

 gradually becomes 

 thicker and firmer. 

 The inserted piece of 

 wall forms the larger 

 part of the wall of the 

 upper cell : the re- 

 mainder is formed by 

 the cap. This mode 

 of division is repeated exactly in the same way, and new caps are 

 formed close below the first one, one for every division. 



FIG. 5i. A (Edogonium ciliatum. A Female plant with 

 three oogonia (og) and dwarf-males (m). B An oogonium 

 with spermatozoid (z) seen entering the oosphere (o) hav- 

 ing passed through an aperture near the summit of the 

 oogonium; m dwarf-male. C Ripe oospore. D (Edogo- 

 nium gemelHparnm. F Portion of a male fiiamm.t from 

 which spertnatozoids (z) are emerging. E Portion of 

 filament of Bulbochcete ; tlie upper oogonium still en- 

 closes the oospore, in the central one the oospore is es- 

 caping while the lower one is empty. FFour zoospores 

 developed from an oospore. G Zcospore germinating. 



