ENCYSTATION OF ACTINOSPHARIUM BICHHORNI. 415 
The strongly-marked chromatin “ haloes,” however, round 
most of the nuclei in the cold culture, both before and subse- 
quent to the primary karyokinesis, struck me as a later 
attempt to reduce the great nuclear preponderance to some 
extent by extrusion of a fine chromatin dust. 
In one cyst from the cold culture I detected two nuclei. 
These are not the result of the primary karyokinesis, but are 
both primary nuclei, of unequal size (22°5 u and 18 w respec- 
tively). ‘They le closely apposed near the centre of the cyst, 
and are both very rich in chromatin (fig. 2). I regard this 
as still further proof of the unmanageably large number of 
nuclei remaining over in a case where lowered temperature 
has caused incompleteness in nuclear elimination. 
Here and there I noticed the inclusion within the cyst-group 
of intensely-staining, round bodies, usually about 6 in 
diameter (fig. 3). At first sight these bear resemblance to 
polar bodies, but their occurrence at this early stage, the hint 
of a central chromatin rosette and of a shrunk nuclear mem- 
brane, decided me to class them as out-thrust dead nuclei 
from the mother-cyst stage. It is quite conceivable that, 
with the nuclear-absorbing power so much lowered by the 
cold, “dead” nuclei may easily escape complete dissolution in 
the mother-cyst, and may linger on through subsequent stages. 
To sum up: 
I. At a low temperature, Actinospheria form small and 
numerous cysts, with nuclei scarcely below normal size, but 
markedly rich in chromatin. 
At a high temperature, the cysts formed are large and few 
in number, with nuclei scarcely larger than those of the cold 
cultures, but poor in chromatin. 
Il. Lowered temperature paralyses the cell-functions to 
some extent. Nuclear elimination is slow and incomplete, as 
indicated by— 
(1) The large number of nuclei retained from the 
mother-cyst reduction to act as centres for primary 
cysts. 
