502 Annals of the South African Museum. 



thicker but less regular outer membrane with numerous attached 

 granules of foreign matter, (3) more closely adpressed cell membrane 

 round the constituent cells, and (4) different behaviour when treated 





. '- -7,'..- * : ' ''% 



. 6. Sphaerocystis Poweri, sp. nov. 



A, Eudorina-form ; B, typical spherical colony ; C, botyroidal form ; D, transition 

 from spherical to Tetraspora-form ; E, Tetraspora-like colony ; F, cell from 

 spherical form ; G-H, motile stage of either spherical or palmelloid form ; 

 G, division of a cell to form two zoospores ; H, mature zoospores a, b, smaller 

 type seen from the side and from the back respectively ; c, larger, more 

 rounded type. 



A x 100 ; B, D x 35 ; C x 150 ; E x 30 ; F-H x 1000. 



with methylene blue, the mucilaginous envelope and matrix reacting 

 differently to the stain. 



The small Eudorina-like colonies appear very soon after the pool 

 has formed ; for example, in the third phase they occur with the 

 Volvojc " Juveniles " collected on 2nd March (Plate XXXVI, A), 

 and may be either spherical or slightly elongated. One measured 



