392 



(Edogoniales 



upper cell is very often one which, owing to repeated previous divisions, 

 possesses a number of apical caps (vide figs. 247 F; 249 B and C; 250 A), and 

 after division it contains most of the protoplast of the original mother-cell. 

 The supporting cells of some species of (Edogonium are decidedly swollen 

 [consult fig. 249 C of GE. lautumniarum Wittr. and fig. 250 A of (E. Borisianum 

 (Le Cl.) Wittr.]. The oogonia are ovoid, globose or depressed-globose in 

 outward form and in (Edogonium they occur singly at intervals along the 

 filament or in series of from 2 to 10. When seriate the oogonia arise in 

 basipetal succession by the repeated divisions of the lower or supporting cell. 



B 



>r - 



K 



H 



Fig. 246. A and B, young plants of (Edogonium Howard! i G. S. West, x 520. C and D, adult 

 plants of (E . inconspicuwm Him, x 500. E H, developmental stages (from the zoogonidium) 

 of (E. rufcscens Wittr. var. Lundellii (Wittr.) Hirn, x 372. I, young plant of CE. Virce- 

 burgense Hirn, x 372. (E I, after Scherffel.) Note the form of the basal cell in all these 

 figures. J, young plant of Bulboch&te intermedia De Bary showing the basal cell (b) and the 

 growing bristle (br) which is the first cell formed from the basal cell. K, part of a branch 

 of B. intermedia showing the first division of an intercalary cell resulting in the formation 

 of a laterally placed bristle (br). J and K, x 300 (after Hirn). 



In the genus Bulbochsete the formation of the oogonium is not so simple 

 as in (Edogonium since it arises as the result of a double division. The first 

 division results in a transverse wall which cuts off a supporting cell from a 

 primary oogonium-cell (fig. 247 A pr). The latter bulges outwards at its 

 upper end, the new wall bursting through the old mother-cell-wall and 

 forming a swelling under the bulbous base of the bristle. This swelling is 

 the young developing oogonium and about the time it attains its full size the 



