The Freshwater Algae of Africa. 



493 



other Volcocaceae, a flat plate is first produced, the four peripheral 

 cells of which at an early stage move forwards to form the second tier. 

 At first the cells of the daughter-colonies are closely crowded together 

 (Fig. 2, 6 and e), but later they diverge more or less and a spherical 

 mucilage-envelope appears about them. The young cells are at first 

 somewhat pear-shaped and only later become spherical. 



It is not at all uncommon to find cells of the mother-colony dividing 

 into more than eight units, but it has been difficult to determine the 

 exact number of cells produced in these cases. In the samples con- 



Fig. 2. — Eudorinella wallichii (Turner), Lemmermann. a. Mature 

 colony, seen from the side. d. Ditto, front view, b, c, ande. Various 

 stages in the formation of daughter-individuals; in b several of the 

 cells show division into morethan eight. /. Single cell, more strongly 

 enlarged, a—e, x 500;/, x 1000. 



taming the Eudorinella 16-celled colonies were occasionally encountered, 

 with an exactly spherical mucilage-envelope and with the cells arranged 

 in very obvious groups of four in the four quadrants; the four cells 

 of each group apparently lay in one plane. It may be that this is a 

 variant of the normal type and that such colonies, by breaking up into 

 four-celled groups, provide those stages in which series of but four 

 cells are found foi*ming daughter- colonies 



In his Treatise on the British Freshwater Algae, Gr. S. West 

 (p. 194;, doubts the necessity of placing Eudorinella in a genus 

 separate from Eudorina. In the very definite arrangement of its cells 

 Eudorinella, however, appears as yet another variant of the Volvo- 

 caceous type, and as such its retention in a, distinct genus seems 

 advisable. 



