100 G. S. WEST ON SOME NEW AFRICAN SPECIES OF VOLVOX. 



The contrasted characters of these species are as follows : 



Volvox globator Ehrenb. 

 [r= V. monoicus Cohn.] 



Diam. of colonies, 420-800/x. 

 Number of cells, 1,000-15,000. 

 Cells small, angular in surface 

 view, and somewhat irregularly 

 produced at the angles. 



Connecting strands of proto- 

 plasm thick and continuous 

 w^ith processes of cells. 



Contractile vacuoles, 2-6 

 (commonly 4). 



Daughter-colonies, regu- 

 larly 8. 



Oospores, 12-40 (average 30); 

 outer wall of ripe oospore verru- 

 cose with conical warts. 



Each androgonidium pro- 

 duces 64 or 128 (rarely 256) 

 antherozoids. 



Antherozoids slender, with 

 elongated nucleus and laterally 

 attached cilia, 



Antherozoids and oospheres 

 commonly produced in different 

 sexual colonies. 



Volvox aureus Ehrenb. 



[= V. minor Stein ; 

 V. dioicus Cohn.] 



Diam. of colonies, 200-680/x,, 

 Number of cells, 200-4,400. 

 Cells larger, almost round in 

 surface view. 



Connecting strands of proto- 

 plasm very delicate (as fine as 

 the cilia) and sharply marked 

 off from the cells. 



Contractile vacuoles, 2. 



Daughter-colonies, 4-14. 



Oospores 3-9 (average 6) ; 

 outer wall of ripe oospore 

 smooth. 



Each androgonidium pro- 

 duces 16 or 32 antherozoids. 



Antherozoids less elongated, 

 with spherical nucleus and 

 terminal cilia. 



Antherozoids and oospheres 

 usually in the same sexual 

 colony. 



Mr. Eousselet's slides contained both these species, a collection 

 made in Baden-Baden in 1906, containing some very fine examples 

 of V. globator with 20-32 ripe oospores. A collection made by 

 Mr. Bousselet at Totteridge contained fine male colonies of 

 V. aureus. 



There is also a third European species V. tertius A. Meyer* 

 which is less well known, and can only be regarded as doubt- 



A. Meyer in Botan. Zeitung, xi. and xii., 189G. 



