ENCYSTATION OF ACTINOSPHARIUM EICHHORNI. 417 
Such individuals as succeed in establishing a certain 
amount of nuclear reduction may encyst; the rest of the 
culture will dwindle and die. The cysts formed show certain 
outward signs of abnormality, such as great unevenness in 
size within one cyst-group, irregularity of form, excessive 
development of silica. 
Treated with reagents, and sectioned in the usual way, 
they are generally found to show corresponding abnormalities 
in the minute structure. Such abnormalities are exactly 
those observed by me in the cold “normal” culture B9, but 
on avery much exaggerated scale. In both cases they may 
be looked upon as the result of a lowered vitality. In the nor- 
mal culture this was induced by lowered temperature. In the 
other cultures it was the result of physiological degeneration. 
Extreme examples of the condition may be induced by the 
co-operation of both factors, as is, indeed, shown by such of 
my degenerate Actinospheeria as encysted in the cold. 
My culture series was too incomplete for me to make 
satisfactory comparisons from successive warm and cold 
cultures during the depression. I shall content myself with 
arranging the described abnormalities in the same order as 
that given at the end of my remarks on the normal cultures, 
adding a brief remark on the fate of the culture and its 
appearance in the other temperature. Such a scheme is, of 
course, rather artificial, but makes comparison easier, and 
brings my results together more compactly. 
In an encystation culture of depressed Actino- 
spheria nuclear elimination tends to be incom- 
plete. 
(1) Too many Nuclei are retained to form Centres 
for Primary Cysts.—This means that the cysts formed 
tend to be smaller than the normal. I found, for instance, 
that 65 w x 55 w was a very common measurement in the cold. 
There were, however, wide deviations from this, and, in the 
warmth especially, I noticed considerable irregularity of size, 
In such cysts the nuclei were of normal size or rather largei. 
The disproportion between the small cysts and their nuclei 
