112 



MORPHOLOGY. 



form a single zoogonidium which has two cilia at the smaller end of the oval 

 body, fig. 114. After swimming around for a time they come to rest, ger- 

 minate, and produce another plant. 



261. Sexual reproduction. Oogonium. The oogonium is formed by the 

 enlargement of a cell at the end of one of the threads, and then the end of the 



Oog 



Coleochaste soluta ; at left branch bearing oogonium (oog) ; antheridia (ant); egg in 

 oogonium and surrounded by enveloping threads ; at center three antherMia open, and one 

 spermatozoid ; at right sporocarp, mature egg inside sporocarp wall. 



cell elongates into a slender tube which opens at the end to form a channel 

 through which the spermatozoid may pass down to the egg. The egg is 

 formed of the contents of the cell (fig. 116). Several oogonia are formed on 



one plant, and in such a 

 plant as C. scutata they are 

 formed in a ring near the 

 margin of the disk. 



262. Antheridia. In C. 

 scutata certain of the cells 

 of the plant divide into four 

 smaller cells, and each one 

 of these becomes an antheri- 

 dium. In C. soluta the an- 

 theridia grow out from the 

 end of terminal cells in the 

 Figs. 117, 118, C. scutata. form of short flasks, some- 



times four in number or less (fig. 116). A single spermatozoid is formed 

 from the contents. It is oval and possesses two long cilia. After swim- 



Fig. 117. 



Two sporocarps still 

 surrounded by thallus. 

 Thallus finally decays and 

 sets sporocarp free. 



Fig. 118. 



Spororarp ruptured b } 

 growth of egg to form cefl 

 mass. Cells of this sporo- 

 phyte forming zoospores. 



