64 CHLOROPHYCEAE 



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 modified forms of other algae. The 

 resistance of the cells to desiccation is aided by a highly concen- 

 trated cell sap and a capacity to imbibe water directly from the air. 



*Chaetophoraceae : Draparnaldia (after J. P. R. Draparnaud). 

 Fig. 45- 

 The plants, which are confined wholly to fresh water, are repre- 

 sented principally by the aerial system, the prostrate system being 



Fig. 45. Draparnaldia. A, portion of plant ( x f). B, same enlarged. C, rhizoids 

 in D. plumosa. D, aplanospores of D. glomerata. (A, B, D, after Oltmanns; 

 C, after Fritsch.) 



entirely absent or else greatly reduced. The young plant is originally 

 attached by means of a much reduced prostrate system together 



