and on a new Species 0/ Protococcus. 431 



spermatic element outside the old cell, as in Cryptoglena lenti- 

 cularis (Annals, l. c). 



I confess that the changes which take place in the indivi- 

 duals which do not send forth their contents in the form of 

 baby groups now inclines me to think that the sporangium may- 

 be produced after the plan first mentioned. But it will be seen 

 that this is a point still undecided, and, as before stated, one 

 which nothing but a stroke of great good fortune can deter- 

 mine. 



It might be asked, also, what are those little cells seen in 

 the central cell of the sporangium under development, and in 

 the central cell also of the groups respectively (figs. 4 & 5, 

 PI. XIV.) ? In the first place, are they cells, or are they cir- 

 cular marks resembling cells, produced by the attachment of 

 the expanded podal ends of the stems of the individuals of the 

 group, respectively, on the central cell ? I incline to the latter 

 view, but admit that I am still in doubt as to the real nature 

 of these apparent cells. 



Do the individuals which produce baby groups produce 

 more than one, as the cells of Pediastrum granulatum (see 

 A. Braun's figures, I. c.) ? Yes. In the group with two baby 

 groups, which I placed aside for examination, one of the 

 parent individuals was but half emptied, and the following 

 morning it was wholly so, while at the final examination there 

 were only four empty cells and five baby groups. Hence one 

 must have produced two ; and this probably was that which at 

 first I saw half-emptied — that is, still retaining another baby 

 group. It is possible, and probable too, therefore, that one 

 parent individual may produce a plurality of baby groups, as 

 in Pediastrum. 



Thinking that Sorastrum spinulosum might be found in the 

 pond of the heath-bog from which was obtained the original sedi- 

 ment in which it was developed in the gum-bottle, I sought for it 

 there about the time that it was most numerous in the latter, 

 but failed to find it anywhere. It is true that the original pool 

 had been drained ; but there were several other depressions of 

 the same kind, in the same locality, filled with bog-water, 

 which, on microscopical examination, did not yield a single 

 specimen. 



Before concluding this communication, I have to allude to 

 a green Protococcus which I found singly and undergoing sub- 

 division in a tank in the Island of Bombay in June 1861, viz. at 

 the time I was led to the view, already noticed, that Pediastrum^ 

 Scenedesmus, and other forms of the kind present in the same 



