Some Observations on the Chromosome Vesicles in the Maturation ete. 95 
a chromosome that was not included with the rest in the large 
vesicle. Two chromosomes are frequently included in a single vesicle 
(Figs. 19, 22), in which case the changes are the same as when one 
chromosome occupies a single vesicle. In Fig. 20, we have all the 
chromosomes in three vesiecles which are so large that they almost 
completely occupy the polar cell. In this instance several of the 
chromosomes still retain their individuality but we can not follow 
the fate of a single chromosome in these vesieles any more than 
we can in the egg nucleus in Figs. 19 or 20. 
Figs. 21 and 22 are from the same ovum being adjacent sections. 
There are in the polar cell in Fig. 22 three bodies which take a 
plasma stain and look much like chromosome vesicles. I think 
that these three bodies are not vesicles but are to be interpreted 
as partly metamorphosed deutoplasmie spheres that have passed into 
this polar cell. Evidence for this conelusion is furnished by the 
character of a similar, although larger body in the egg itself, of 
this same figure, Iying near the male nucleus which is undoubtedly 
a yolk sphere. Furthermore, it is not unusual for yolk bodies to 
be found in the polar cells in Mollusca, and especially in these 
three Nudibranchs. I have further noticed in segmentation stages 
that the deutoplasm did not take as heavy a stain as it became 
partly metamorphosed into eytoplasm. 
Diseussion. Chromosome vesicles similar in many particulars 
to the one here described are also found in the spermatogenesis of 
Brachystola magna (SUTTON, '01) They occur in late anaphase and 
the eontained chromosome retains its identity more definitely than 
in the cases eited in this paper. LitLıE (’02), finds in experimental 
work on Chaetopterus eggs that chromosome vesicles may appear 
around each particle of chromatie substancee. In diseussing this 
phase of the question he states (p. 490) »Even the smallest diseer- 
nible particles of chromatin exereise, apparently, a liquifying effeet 
on the eytoplasm, and thus appear to lie in vacuoles (Fig. 27), a 
condition analogous to the return of the nucleus to its resting con- 
ditione. COoNKLIN describes for Crepidula chromosome vesicles (linin 
sheaths) in the metaphase of the first maturation but does not find 
them at other stages. Harcırr ('04) finds in the natural development 
of Pennaria tiarella chromosome vesieles similar to the ones in the 
eggs of Chaetöpterus and these Nudibranchs. Chromosome vesiecles 
are found then in both normal and artificially developing eggs. That 
such unusual changes should oceur in both normal and artifieial 
