412 



PROTOPHYTA 



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r^:,-^' ^(B^§) ^'' '^ 



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Each cell contains a nucleus and a vacuole ; the green protoplasmic 

 contents break up ultimately into zoospores of a very peculiar form, 

 conical, with two cilia attached to the nearly flat base, recalling those of 



Hydrurus (p. 256). 



In Didyosphceriiun Nag., 

 which ought possibly to be 

 placed under the Coenobieae, the 

 free-swimming colony is com- 

 posed of globular or kidney- 

 shaped green gonids connected 

 together by delicate threads of 

 mucilage. New colonies are 

 formed by repeated biparti- 

 tion of the gonids, which fre- 

 quently exist for a time without 

 any enclosing cell-wall. Mis- 

 chococcus Nag. consists of minute globular gonids connected together 

 in an arborescent manner and enclosed in a hyaline envelope, the whole 

 colony attached to fresh-water algae. Borzi (Malpighia, 1888, p. 133) 

 describes also a palmelloid form of Mischococcus, the cells of which 

 give birth to megazoospores with only a single cilium. The dendroidal 

 form may spring either from these zoospores or directly from the 

 palmella- cells ; its cells also produce uniciliated swarm-spores, similar to 

 the zoospores but smaller. They are apparently zoogametes conjuga- 



■^ 





Fig. 337. — HaplosphiEra ■viridix Schm. Globe ( x So), 

 and zoospore (x 150). (After Schmitz.) 



Fig. 338. — Dictyosp]ia:rium 7-cniforine 

 Buln. (x 400). (After Cooke.) 



Fig. 339. — Mischococcics conferzncola Nag. 

 (x 400). (After Cooke.) 



ting to produce a biciliated zoosperm. Botrydina Breb., found on 

 moist ground, trunks of trees, cvic., is composed of a number of minute 

 gonids enclosed in a pear-shaped or globular hyaline envelope, as much 

 as o-i mm. in diameter, and resembling Aphanocapsa among the 

 Chroococcaceae. It may possibly be allied to Botrydium. 



Characium A. Br. is a minute green organism attached by a gela- 

 tinous stalk to alg;£ or other fresh-water plants, often in groups. It is. 



