396 



(Edogoniales 



a little narrower than the filament in which they are produced. The first 

 androgonidangium always arises by the division of a vegetative cell and the 

 others are formed in a manner very similar to the development of a multi- 

 cellular antheridium. In fact, there is often a very close resemblance between 

 the latter and a chain of androgonidangia. Sometimes the androgonidangia 

 occur in the same filaments as the oogonia (gynandrosporous forms) or they 

 may only be formed in separate filaments (idioandrosporous forms), and in 



Fig. 251. A, Bulbochsete subintcr media Elfv. B, B. Nordstedtii Wittr. C, B. nana Wittr. a, 

 antheridium; and, androgonidangium; n, nannandrium ; oo, oogoniuin. All x 495. 



the former case they may, like the antheridia of the monoecious species, 

 occupy more or less constant positions relative to the oogonia. 



The androgonidia come to rest either on the wall of the oogonium or on 

 the supporting cells and on germination each produces a ' dwarf male ' or 

 nannandrium (fig. 250 A C). These tiny male plants are sometimes uni- 

 cellular, the antherozoids being produced within the single cell. More often 

 they are bicellular or pluricellular, in which cases the antheridia may arise in 

 one of two ways. In many species a transverse wall appears in the originally 



