Protococcacece 



229 



W. & G. S. West is a curious species in which the mother-cell-walls throw off 

 a number of integuments, several generations being disposed in a fan-shaped 

 manner and held in position by the partly exuviated layers of the mother-cell- 

 walls; length of cells 24 26'5 p. ; breadth 1317 /* ; fig. 98 B. 



Genus Eremosphsera De Bary, 1858. [Chlorosphcera Hen- 

 trey, 1859.] The cells are solitary, large, and spherical, with a 

 thick, firm cell-wall distinctly differentiated into two layers. Each 

 cell contains a large number of small parietal chloroplasts furnished 

 with a conical projection directed towards the centre of the cell. 

 There is one pyrenoid in each chloroplast. The nucleus is gene- 

 rally contained in a small mass of protoplasm suspended in the 



Fig. 99. Ervmuxplucru viridis De Bary, from near Clapham, W. Yorks. ( x 175). 



central region of the cell by a network of protoplasmic threads. 

 Multiplication takes place by the division of the contents of a 

 mother-cell into two or four smaller but similar daughter-cells 

 (autospores), which are set free by the rupture of the mother-cell- 

 wall. Chodat 1 has described the occurrence of certain polymorphic 

 forms of this Alga, but although I have examined large quantities 

 of it from every part of the British Islands, and from elsewhere, 

 I have never yet seen any trace of such forms. Specimens kept 

 under cultivation for two years developed no forms other than 

 globular daughter-cells. Moore 2 also disputes the alleged poly- 

 morphism of this Alga. 



E. viridis De Bary is widely distributed all over the British Islands, more 

 especially in Sphagnum-bogs. It is a constant associate of certain Desmidx. 

 The cells vary from 55 200 p. in diameter; fig. 99. 



Genus Palmellococcus Chodat, 1894. \JProtococcus Ag. 1824 

 (in part).] The cells are more or less globular, with a firm cell- 

 wall, and aggregated to form a thin mucous stratum. There is in 



1 Chodat in Botan. Zeitung, liii, 1895, t. v. 



2 Moore in Proc. Amer. Assoc. Adv. Sci. 1900, pp. 278, 279. 



