No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 
they never lie in contact with the latter and are frequently 
situated at some distance from it. Were they buds from the 
large one, one would expect to find in them vacuoles such as 
occur in the large nucleolus, but they never contain vacuoles. 
In one nucleus (Fig. 207) I saw a disc-shaped mass apposed to 
the inner surface of the nuclear membrane, which stained more 
intensely than the chromatin. Such a peripheral mass may 
be regarded as a substance taken up from the cytoplasm by 
the nucleus, which, after passing through the nuclear mem¬ 
brane, undergoes a chemical change to such an extent that it 
stains with haematoxylin. The minute nucleoli may stand in 
a genetic connection with such a mass of substance, that is, be 
portions of a substance assimilated by the nucleus and after¬ 
wards scattered through the latter. They might serve as 
nourishment for the chromatin threads with which they are 
often in contact. 
In seven nuclei out of about one hundred or more examined the 
large nucleoli differed much from the ordinary type described 
above. In one egg pouch there was a smaller ovum apposed to 
the animal pole of a larger one (Fig. 211); a normal nucleolus 
was present in the nucleus of the smaller one. But in the larger 
ovum two nuclei were present, in close contact with one another, 
though separated by a membrane (coalesced nuclear membrane). 
It is in each of these latter nuclei that an abnormal nucleolus 
is present. Each of these nucleoli is finely granular, without 
enclosed vacuoles, and stains faintly with haematoxylin ; the 
one is regular in outline, but the other is jagged at one pole, 
and a ring-shaped portion of its substance stains more deeply 
than the remaining portion. In another ovum I also found two 
nuclei, in each of which was a nucleolus similar to those just 
described. In still another ovum two nuclei were found in 
contact with each other, the nucleolus of one of which was 
similar to those here described, but the nucleolus of the other 
nucleus was intermediate in structure between these and the 
ordinary type of nucleoli (Fig. 210). In only one case was 
such an abnormal nucleolus present within an ovum contained 
in a gonophore (Fig. 208); in the other six cases the abnormal 
nucleoli were in ova of egg pouches. 
