398 QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 
Chlamydomonas.—The species of this genus are probably 
all motile stages of forms which are placed in other genera. 
Ch. Pulvisculus, the least known, could be traced, according 
to Kiitzing, into Stigeoclonium stellare ; but he probably 
confused with it the zoospores of that alga. With more pro- 
bability Cienkowski has described the development of the 
macrozoospores into a species of Glwocystis, which only 
differs from Plewrococcus in the thicker walls of the cells, 
and is hardly generically distinct. It is true that his figure 
shows a more rounded contour than the ovoid zoospores of 
Chlamydomonas usually possess. But as he has traced the 
same course of development in two other species of the genus, 
it is exceedingly probable that Gleocystis or Pleurococcus 
is the normal quiescent stage which they all attain. The 
authors of the ‘ Micrographic Dictionary ’ describe under the 
head of Protococcus viridis a Pleurococcoid alga which would 
probably be placed by Rabenhorst under Gleocystis, and of 
this they also state that a Chlamydomonas is the motile 
stage. Reinhardt has observed the conjugation of Chlamydo- 
monas Pulvisculus,! and Gorojankin states that he has seen 
this take place between a macro- and a micro-zoospore,”? an 
observation which, if confirmed, may be compared with what 
takes place in Pandorina. Rostafinski has also observed the 
conjugation of the microzoospores of Ch. multifilis, Fres. The 
zygozoospore, after about six weeks, developed by cell-division 
into a Pleurococcoid alga.* It appears, therefore, probable 
that this stage is reproduced in all cases under particular 
suitable conditions by both macrozoospores and zygozoo- 
spores. 
Pandorinee.—In considering the position which the Volvo- 
cinaceé holdin Sachs’s classification, I found myself confronted 
by the same difficulties which had also struck Cohn (see supra, 
p- 312). The group, in point of fact, includes two distinct 
types of reproduction ; and it seemed to me justifiable—taking 
into consideration the importance, on the whole, of the points 
which Sachs’s classification brings out—to run the risk of 
doing some violence to what at first sight appears to be a 
natural assemblage of genera in order to bring it into con- 
formity with that classification. I accordingly proposed 
(p. 810) to limit Volvocinee to Volvox and Eudorina. The 
remaining genera which are usually also placed amongst the 
Volwocinee 1 proposed to separate under the name of 
Pandorinea. Within the last few weeks I have received, 
1 * Bot. Jahresbericht,’ 1873, p. 22. 
2 Quoted by Rostafinski, ‘Mém. Soc. Cherb.,’ |. ¢., p. 146. 
>“ Bot, Zeit., 1871, p. 787. 
