386 



(Edogoniales 



generally somewhat tumid with a basal holdfast (fig. 244; fig. 245 A, G H), 

 but in a few of the smaller species of (Edogonium it is depressed-ellipsoid 



(fig. 246 B D). The apical cell is often 

 bluntly rounded, but frequently possesses 

 a conical cap (fig. 244 /). In some species 

 the cap is apiculate, in which case this 

 character is shown in the very first cell 

 developed from the zoogonidium (fig. 245 

 A)', and in (Edogonium ciliatum (Hass.) 

 Pringsh. the terminal cell is greatly 

 elongated to form a delicate hair. In 

 the genus Bulbochsete nearly all the cells, 

 except at the points of insertion of the 

 branches, bear at their dilated upper 

 extremities a laterally placed bristle. 

 This bristle is hollow, with a swollen 

 bulbous base, and may be more than 

 1 mm. in length (fig. 242 ; fig. 251). The 

 terminal cell of each branch is always 

 furnished with a bristle. 



The cell-wall consists of a thick cellu- 

 lose layer outside which is a thin cuticle 

 (fig. 241 B). In several species of Bulbo- 

 chsete and in one or two species of 

 (Edogonium the exterior of the wall is 

 finely granulate. 



The protoplast is largely disposed as 

 a parietal layer in which the chloroplast 

 is embedded, and the cells are uninucleate. 

 The nucleus may be more or less centrally 

 located or it may occupy a parietal position, 

 and in most cases it possesses a prominent 

 nucleolus. The chloroplast is somewhat 

 variable in character, but is always parietal 

 and generally in the form of a reticulum 

 (fig. 240 A}. In the smaller species of (Edogonium the network is much 

 reduced, but in the larger species it may be rather complex and the pieces 

 of the reticulum often have a tendency to become separate and distinct 

 (fig. 240 B). The chloroplast is furnished with one or more pyrenoids, the 

 number depending largely upon the size of the cells. In the smaller species 

 there is generally only one pyrenoid (fig. 240 (7), but in the larger species 

 there may be many pyrenoids distributed through the reticulum. Sometimes 



Fig. 240. A, B and C, cells of different 

 species of (Edogonium to show the 

 variable character of the parietal 

 chloroplast. D, cell of (E, giganteum 

 Kiitz. showing a succession of apical 

 caps, n, nucleus ; py, pyrenoid ; 

 st, starch. All x 430. 



