ALGAL AND FUNGAL PROTISTS 27 



the whole cytoplasm, there being no chromatophores. 

 Some algae grow in pure cultures like bacteria. Charpentier 

 found that Cystococcus humicola grown in a liquid medium 

 containing 1 per cent, of glucose besides the usual salts (phos- 

 phates, nitrates, and sulphates) would live in the absence of 

 light, taking its carbon from the glucose. Grown in the 

 light the plant multiplied more rapidly and produced no 

 starch, which was abundant when the plant was grown in 

 the dark. He regards Cystococcus as a " plante de passage " 

 prepared to adapt itself to a mode of life like that of the 

 fungus, Mucor. 



Able to take carbon from the air green algae seldom 

 adopt a parasitic life, but one of them, Chlorochytrium 

 lemnae is parasitic on duckweed. The genus was founded 

 in 1872 by Cohn, who, as B. M. Bristol informs us, described 

 it as follows : " Endophytic green unicell, in which multi- 

 plication takes place by means of numerous zoogonidia 

 produced by free cell-division, first into large segments, 

 later into innumerable pear-shaped bodies which are ex- 

 truded through the tubular process on the cell- wall." The 

 nucleus in Miss Bristol's illustration is central and has a 

 large nucleolus. 



Another parasitic alga, Rhodochytrium spilanthidis, 

 deserves close attention. It resembles the fungi in being 

 devoid of chlorophyll, and is strictly parasitic. Common in 

 N. Carolina and Equador it has been reported in only one 

 other district. Rhodochytrium occurs in different host-plants. 



