416 DORIS L. MACKINNON. 
(2) The superabundance of chromatin in these nuclei, as 
suggested by “ haloes.” 
(3) The occurrence of two nuclei in one primary cyst. 
(4) The occurrence of occasional “ dead ” nuclei within the 
groups of primary cysts. 
Hitherto I have described the effect of cold on a culture of 
Actinospheerium that encysted quite normally. The majority 
cf my cultures, however, encysted during the oncome of a 
“depression ’’-wave, and showed many abnormalities of 
structure. A few points noticed seem to be worthy of brief 
description. Full account of the effect of temperature on 
cultures of degenerate Actinospherium will be given by my 
fellow-student, Miss Boissevain. 
Where there was a tendency to abnormality it made itself 
noticeable in the cold culture first, as a rule—probably the 
next set of cultures would show abnormalities in the warmth. 
Finally, a stage would be reached when both sides of the 
culture would entirely refuse to encyst, or would encyst so 
abnormally and feebly that further development was im- 
possible, and the cysts disintegrated in that stage. 
Examination of non-encysted members of such cultures: 
gives a clue to this condition. The organisms are under- 
soing a period of “depression.” Prolonged function has led 
to an overwhelming nuclear preponderance, and, though by 
out-thrust of chromatin and nuclear fusion, attempts are being 
made to bring the relation back to the normal, yet the 
nuclear mass is So unmanageably great that the “reducing ”- 
power of the cytoplasm is insufficient to cope with it, and, in 
extreme cases, the limits within which. satisfactory encysta- 
tion is possible, are never reached. Further, if it be granted 
that abnormal nuclear dimensions are injurious to cell-life, 
then the very presence of this pathological condition in the 
cell must render the cytoplasm still less équal to meet the 
heavy demand put on it. | 
