420 DORIS L. MACKINNON. 
stain. In appearance they bear avery strong resemblance to 
polar bodies, but their number, fourteen, does not fit in with 
the number of the nuclei, which is six. Possibly, however, 
some of them may be the last remnants of “ dead” nuclei. 
The Delafield’s hematoxylin brought out clearly the broad 
zone of ‘ Dotter-plattchen,” just within the silica coat. 
I was unable to decide as to the stage that this cyst has 
reached. I incline to think it a mother-cyst in which the 
nuclei have swelled out to the size of primary-cyst nuclei; but 
the power to form separate cysts round these has been 
lost. 
(3) The Retention within the Cyst Group of Dead 
Nuclei from the Mother-cyst.—This occurs freely in ~ 
most of the cases already described. In both warm and 
cold cultures the cyst-groups are very commonly accom- 
panied by such nuclei in various stages of “ shrinkage.” 
Fig. 8. Here is a group of seven primary cysts from B2 
(cold). The nuclei are in process of the primary karyokinesis. 
Twelve out-thrust nuclei remain round the group, and show 
still quite clearly their original structure. 
Fig. 9 is a section from a group of twenty-four secondary 
cysts and conjugation-cysts from the room-temperature 
culture of A2. Most of the cysts are in process of polar- 
body formation, but are not very clearly marked off from one 
another. Within the common cyst envelope are as many as 
forty-six nuclei of still quite appreciable dimensions. 
I failed to observe out-thrust nuclei surviving till later 
stages than this. 
I am inclined to think that nuclei are thrust out bodily 
from the early stages in the mother-cyst as soon as, from 
either of the causes suggested (i.e. lowered temperature and 
degeneration), nuclear absorption by the cytoplasm has been 
weakened. 
In unencysted Actinospheria Hertwig observes that, from 
such as have suffered hyperplasia or hypertrophy of the 
nucleus, parts of the organism, containing numerous nuclei, 
are thrust out bodily (‘ Physiolog. Deg. bei Actinosph.’) 
