EUPHYCOPHYTA 



75 



The cells, which are globose in shape and occasionally branched, 

 are single, or else as many as four may be united into a group. 

 Under certain cultural conditions 

 branching may be copious. Each 

 cell contains one chloroplast and 

 there are no pyrenoids. The sole 

 method of reproduction is 

 through vegetative division in 

 three planes when one may find 

 up to fifty cells in a group. There 

 is probably only one species, P. 

 naegelii, all the other so-called 

 species being reduced or modi- 

 fied forms of other algae. The resistance of the cells to desiccation 

 is aided by a highly concentrated cell sap and a capacity to imbibe 

 water directly from the air. 



Trentepohliaceae : Cephaleuros {cephal, head; euros, broad). Fig. 

 40 



Fig 39 Pleurococcus naegelii. A, 

 single cell. B, single-celled colony. C, 

 normal colony. D-F, thread for- 

 mation. (After Fritsch.) 



Fig. 40 Cephaleuros. A, leaf of Magnolia infected with C. virescens. 

 B, transverse section of leaf of Michelia fuscata showing filaments 

 and rhizoids (r) of C. virescens. C, transverse section of leaf of 

 Zizyphus with C. minimus showing sporangial branches. D, 

 sporangia of C mycoidea. (A, after Smith; B, C, after Fritsch; D, 



after Oltmanns.) 



