ENOYSTATION OF ACTINOSPH#ARIUM EICHHORNI. 419 
outwards, and in one case, that of the largest nucleus, the 
nuclear membrane seemed to have disappeared at one point, 
and the whole nuclear content is streaming out. 
(c) No other member of this culture, B 11 (cold), got beyond 
the mother-cyst stage. In fig. 6 is shown one of these cysts. 
This shows elimination to have been so imperfect that a quite 
excessive number of nuclei remain; in the cyst figured there 
were 278. These have all shrunk and died, but remain as 
darkly-staining spots (6°54 to 9 in diameter), not near the 
borders of the cyst, but aggregated in little strings and groups. 
Each group hes in an “island” of normally-staining cyto- 
plasm surrounded by non-staining brownish material, in which 
are Shrinkage rents. This is an instance of “ pycnosis,” when 
the nuclei die off without being further disposed of, until the 
whole cyst disintegrates. 
(The corresponding warm culture of B11 showed such 
abnormalities as great fluctuation in size of cysts, and frequent 
occurrence of non-absorbed nuclei.) 
(2) Occurrence of more than one Nucleus in a 
Cyst.—In Culture A 2 I noticed a few abnormalities in the 
warm and room temperature cultures, while the cold culture 
encysted only very feebly. In one cyst from the warm culture 
I counted as many as six nuclei (fig. 7). The cyst was the 
only one formed by the individual, and measures 120 uX111 p, 
much of the bulk being due to the silica, which is about 18 I 
thick. The nuclei are arranged in a group round a central 
point. They are of much the same size, 16 X 14, and of 
markedly elongated form. On one side, generally that towards 
the exterior, they have shrunk away a little from the cyto- 
plasm. At first, I took them to be heteropolar, but subsequent 
use of Delafield’s hematoxylin failed to bring out any such 
arrangement of the chromatin. The nuclei are, in fact, singu- 
larly devoid of chromatin, and the nuclear reticulum is very 
faint, and free from chromatin aggregations of any size. In 
the cytoplasm lie also fourteen smaller darkly-staining bodies, 
measuring about 4 in diameter, and each surrounded by a 
vacuole. ‘These remained unaffected by the haematoxylin 
