3802 QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 
They come to rest, “ germinate,”’ and so reproduce asexually 
the parent plant. 
The function of the microzoospores, on the other hand is 
sexual. They conjugate and the zygozoospore (Areschoug), 
after passing into a resting phase, no doubt, also reproduces 
the parent plant. 
The following are the cases in which up to the present 
time the conjugation of zoospores has been observed. 
PANDORINEX (Dyer).—Chlamydomonas is a microscopic 
organism which consists of a green protoplasmic mass with 
a lateral speck of red pigment, varying in form from 
ovoid to globular and furnished with two or four vibratile 
cilia, attached at a hyaline apex where the green colouring 
matter is more or less absent. It is bounded by a delicate 
closely applied cellulose wall; Chlamydococcus only differs 
in the wall being separated from the green contents by an 
interspace. By division into two or four each individual 
Chlamydomonas gives rise to macrozoospores which eventu- 
ally attain the same size and appearance as the parent. 
Occasionally, however, the division proceeds further, and 
eight daughter cells are produced —the microzoospores. 
Rostafinski! first observed that these microzoospores conju- 
gated. ‘Two of them touch by their colourless extremities 
and then gradually fuse together, eventually producing a 
cell with a rounded contour, but with eight cilia and two 
lateral pigment spots. The colourless apex of this zygozoo- 
spore soon disappears; the eight cilia follow and the zygo- 
zoospore passes into the resting condition. After having 
been allowed to dry up and then again moistened it gave 
rise—not to new zoospores, but to vegetative forms arising 
from repeated cell division and referable to the genus Pleuro- 
coccus.” 
1 « Beobachtungen iiber Paarung von Schwirmsporen,” von J. T. Ros- 
tafinski, ‘ Botanische Zeitung,’ 1871, p. 785. 
7 If we follow the example of Bornet (‘ Ann. des Sc. Nat.,’ 3e sér., tom. 
xvii) and unite Pleurococcus with Protococcus, we shall then have an in- 
telligible view of the complete life-history of a type the name of which is at 
any rate a very familiar one. 
Rabenhorst (‘Flora Alg. Aq. Dule.’) maintains Pleurococcus vulgaris, 
Menegh., and Protoccus viridis, Ag., not merely as distinct species, but as 
belonging to separate families—the former to the Palmedlacea, the latter 
to the Protococcace@. At the same time he remarks with regard to Pro- 
tococcus viridis, ‘fieri potest ut Pleurococci vulgaris status pro ratione loci 
natalis siccioris sit.” Pleurococcus vulgaris may probably, therefore, be 
regarded as a more actively vegetative condition of Protococcus viridis, 
the only real difference between the two being, that one undergoes cell- 
division, while the other does not. As Chlamydomonas Pulvisculus, after 
the conjugation of its zoospores, develops into a Plewrococcus, it also may 
