i8o 
W. B. Grove. 
upon too narrow a basis; a longer study would probably have 
revealed a greater variety of states. Unfortunately, however, 
Kofoid says, the species entirely disappeared after eleven days 
(June 16-27), a kind of disappointment from which many an algolo- 
gist has similarly suffered. 
In July, 1903, Merton (11) found P. illinoiensis in Germany 
at Heidelberg and also received it in 1907 from the Bavarian 
Palatinate; it was accompanied by Eudorina and Pandorina. In 
the year 1907, it began to appear, he says, in the latter half of June 
increasing during July, towards the end of which month he found 
for the first time the sexual stages; eight days later it had all 
disappeared. The colonies were all larger than those of the Eudorina', 
each consisted of 32 cells, the vegetative cells measuring 11-12/u., 
the gonidial cells 19-21 /x. The megagametes were a little larger; the 
microgametes formed plakeas of 64 or 128 cells ; the zygotes had a 
rather thick smooth membrane and finally a yellow-brown colour. 
Fritsch in 1904 (7) found P. californica in tanks in Ceylon, 
associated with a form which could not be distinguished from 
Eudorina elegans. 
In 1905, W. West and G. S. West (16, p. 506, pi. 6, f. 14), 
recorded Pleodorina californica from a lake in Lewis, Outer Hebrides. 
The colonies occurred among ordinary globular Eudorina elegans ; 
they were broadly ellipsoidal with slight posterior lobes, hut had 
only 32 cells, about half of them being vegetative : thus agreeing 
with neither of the described species of Pleodorina, but sharing the 
characters of both. The vegetative cells measured 6 , 5-7 , 5ju,, the 
gonidial cells 13-4-16 5, i.e., in a ratio of about 1:2. It is plausibly 
suggested (l.c., p. 507) that these individuals were only Pleodorina - 
states of the Eudorina. 
Again, in 1906, the same authors found in a lake in Galway 
(17, p. 134, pi. 10, Figs. 7-8), among an immense number of ordinary 
Eudorina, two interesting colonies which differed from the rest. 
They were still gobular, but small and large living cells (diameters 
about as 1 : 2^) were indiscriminately mixed, with a few disintegrated 
dead cells scattered among them in one case. The authors 
considered these colonies to he mere states of the Eudorina. 
At the end of April, 1911, Chatton (3) discovered Pleodorina 
californica in a little pool in the south of France. It was accompanied 
as usual, by Eudorina and Pandorina, and disappeared at the beginning 
of July. The rotation was always clockwise. He observed for 
the first time the sexual reproduction, which continued only for a 
