Sexual reproduction 



395 



The antherozoids are not always formed in quite the same way. In some 

 of the smaller species of (Edogonium the protoplast of the antheridial cell 

 forms one antherozoid. This is exceptional, as in general two antherozoids 

 arise in each antheridial cell (fig. 247 G E). In some species of (Edogonium, 

 especially the dioecious macrandrous species, they are formed by a vertical 

 division of the protoplast, the two antherozoids being side by side in the 



Fig. 250. Dioecious nannandrons species of (Edogonium. A, (E. Borisianum (Le Cl.) Wittr., 

 x 400. B, (E. crassiiisculum Wittr. var. idioandrosporum Nordst. & Wittr., x 220. G and D, 

 (E. concatenatum (Hass.) Wittr., x300; C, supporting cell of oogonium (which is just about 

 to be formed by cell-division) carrying two nannandria ; D, chain of androgonidangia. 

 fl, antheridium ; and, androgonidangium ; s, supporting cell of antheridium; sp, supporting 

 cell of oogonium. E, androgonidangia (and) of (E. Braunii Klitz. showing escape of andro- 

 gonidia (as). (C E, after Hirn.) 



antheridial cell, but in many others and in Bulbochtete the division is trans- 

 verse so that the antherozoids are one over the other. 



In the dioecious nannandrous species the male plants are very small and 

 are epiphytic on the female plants. They are developed from special motile 

 cells known as androgonidia (or androspores) which are produced in andro- 

 gonidangia (fig. 250 D and E and). The latter, which are often called 

 androsporangia, are short cells, solitary or in chains, and they are sometimes 



