COLEOCHyETE. 



I5S 



ger- 



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

 bo'ly> fig- 157. After swimming around for a time thev come to re=t, 

 minate. and produce another plaTit. 



327. Sexual reproduction. — Oogonium. — The oogonium is formed bv the 

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



Oog-- 



Fig. 150. 



Coleoch^te soluta : at left branch bearing oogonium ^ooi:)\ antheridia imit): egg in 

 oogonium and surrounded by enveloping threads : at center three antheridia open, and" one 

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



cell elongates into a slender tube wliich 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 (tig. 159). Several oogonia are farmed on 



one plant, and in such a 



plant as C. scutata they are 



formed in a ring near the 



margin of the disk. 



328. Antheridia.— In C. 



scutata certain of the cells 



of the plant divide into four 



smaller cells, and each ur.e 



of these becomes an antlieri- 



dium. Ii] C. solula the an- 



Fig-i6o. 

 Two sporocarps still 

 surrounded bv tballus 



Fig iSi. 



Sporocarp ruptured b \ 



growth of egg to form ccfl theridia grow out from the 



Thallus finally decays and mass. Cells of this sporo. 



sets sporocarp free. 



p!>\te forming zoospores. 



end of terminal cells in the 

 Figs.i6o, 161. C- scutata. fnrm of short flasks. Some- 



times four in numlier or less ifig. 159). A single spermatozoid is formed 

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



