372 MR. 8. LE M. MOORE’S STUDIES 
ciliation has been made out only in the case of a few gonidia, and 
after much manipulation with the mirror. To this day I am in 
doubt whether, in any of its typical forms, Apiocystis ever is 
eciliate throughout life; but there is no doubt that eciliate 
phases do occur, as will now be explained. Should the tem- 
perature fall below some unascertained point, growth of the zoo- 
sporangium is greatly impeded: instead of developing iuto the 
ordinary form, it remains stunted, and tends to increase more or 
less equally in all three dimensions, sometimes with predominance 
in the transverse plane (Pl. LV. fig. 20). In this state it is liable 
to be mistaken for a species of Palmella, but can be at once distin- 
guished by its usually remaining attached to the Cladophora 
thread. When, as sometimes happens, it becomes detached, it can 
be easily known from Palmella on account of its saccate character, 
whieh enables one, ou focussing down, to come upon a second 
stratum of underlying gonidia. "There is really very little dif- 
ference between the condition shown in fig. 9a and that in figs. 20 
and 21, for instance: in the latter the process of gelatinization 
is much more gradual; so that one may watch these Palmella 
states for days together without detecting any difference in 
them. 
Division of the cells in these Palmella masses may frequently 
be seen, and investing walls sometimes surround the cells just as 
in the ordinary forms; but cilia are never to be discovered. 
During the heavy rains of June, July, and August, and occa- 
sionally at an earlier period of the year, the Apiocystis wall fre- 
quently assumed the curious appearance shown by figs. 17-19, it 
being studded with minute highly refractive particles, which I 
suppose must have been tiny particles of mud from the pond's 
bottom, for the frequent and violent storms rendered the water 
very muddy. I do not know whether adhesion of these particles 
was the cause or the consequence of gelatinization—probably the 
latter; but it almost always happens, though not invariably, that 
when once the wall has become studded with them, the rapid 
methods of zoospore-liberation are in abeyance, the zoosporangia 
growing from this time forward usually in the Palmella form. 
Speeimens with these studded walls are almost always eciliate: 
fig. 19 shows an exceptional eondition, in that the gonidia are 
furnished with long cilia. A singular point is that very young 
zoosporangia may sometimes be affected in this way ; such a case 
is shown at fig. 17, where there is but one eciliate gonidium ; and 
