QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 397 
tafinski considers a monstrosity arising from the adhesion of 
two macrozoospores, a circumstance which he believes often 
to happen. It must be very difficult to discriminate such an 
adventitious adhesion of a pair of zoospores from the actual 
process of conjugation. In this case, however, since macro- 
and not micro-zoospores were in question, an adhesion and 
not a conjugation is probably the right explanation. Rosta- 
finski now regards Chlamydococcus as altogether asexual. The 
microzoospores which are produced during the night have the 
singular property of collecting on the side of the vessel in 
which they are placed which is least illuminated. Cultivated 
in one of Van Tieghem’s cells, they passed into the resting 
stage, assumed a red colour, gradually acquired the size of 
the normal resting cells, and finally gave rise, by division into 
four, to zoospores. Rostafinski has also found that Chlamy- 
doccus pluvialis is able to exist on snow and in ice, and 
considers that it and Ch. nivalis are identical. He therefore 
substitutes Agardh’s generic name Hematococcus (1828) for 
A. Braun’s (1851). He further identifies with Haematococcus 
Volvox lacustris, which Girod-Chantrans described (in 1797) 
as giving a fine red colour to water near Besancon, and 
proposes, on the principles which are adopted by many 
foreign botanists, to rename the plant Hematococcus lacustris 
(Girod). 
Protococcus—The genus which Agardh founded (1824) 
under this name has furnished material for Protococcus, 
Kiitz., in which the cells are isolated ; Plewrococcus, Menegh., 
where they are quaternate ; and Cystococcus, Nag., which has 
them irregularly aggregated. Rabenhorst suggests that Pro- 
tococcus viridis, the solitary species of the genus, may be a 
state of Pleurococcus vulgaris. Protococcus, in its restricted 
sense, is supposed not to exhibit any increase of its quiescent 
stage by cell-division. But this may be due to unfavorable 
external conditions. Pleurococcus vulgaris, on the other 
hand, is stated not to develop zoospores.! The two modes of 
reproduction are therefore in this case mutually exclusive. 
Cystococcus humicola supplies many lichens, such as 
Parmela parietina, with their gonidia; under these. circum- 
stances they still retain the power of producing zoospores.” 
1*Micrographic Dictionary,’ under Chlorococeum. Ch. vulgare, Grev., is 
asynonym of Pleurococcus vulgaris. The editors of the last edition of the 
‘ Micrographic Dictionary,’ forgetting this, have given a full description and 
figure of the species under Chlorococcum, and have added a further descrip- 
tion and figure (both from Rabenhorst) under Pleurococcus. 
> Famintzin and Baranetzky,\‘ Ann. des Se. Nat.,’ 5e sér., vol. viii (1867), 
p. 137; Woronin, vol. xvi (1872), p. 324. 
