.r. GKAY. 
4ol: 
beciuise (1) they can always be foimd iu the female pro- 
nncleiis, and nevei- in the male ; (2) in eggs in which more 
than one sperm has entered only one lai-ge vesicle is found. 
Bhg. 8 shows an egg with a fusion nucleus showing a con- 
spicuous and very darkly stained vesicle, while in the accessory 
sperm nuclei no such large bodies are found (only small dark 
dots among the chromosomes). 
I’hese vesicles are visible within the nuclear membrane 
before the chromosomes begin to be formed (fig. 6). They 
appear to arise from the network of the nucleus in the follow- 
ing manner : the outline of the vesicle is fii-st distinguishable 
as a circle of dots enclosing minute granules of a darker 
staining substance. As the network of the nucleus becomes 
darkei’, preparatory to the formation of the chromosomes 
(which in these eggs arise as veiw fine crinkled threads), the 
interior of the vesicles gradually becomes more uniform, and 
it appears as though the granules gradually diffuse themselves 
until the whole vesicle is of a homogeneous nature. Fig. 9 
shows a vesicle in the process of formation. In fig. 10 the 
vesicles are in such a conditiou as they are iisually found in 
the later phases of division. Fig. 11 shows a nucleus as it is 
seen just before the nuclear membrane disappears: thirty-six 
or more chromosomes are present together with a large and a 
small vesicle. In mitotic phases of a later stage all the 
vesicles except the large one disappear, or can be only recog- 
nised among the chromosomes as small dark dots. The large 
vesicle, however, persists. Figs. 12-15 show the vesicle 
during the inetapluise, anaphase, and telophase conditions of 
the spindle. 
The ultimate fate of the large vesicle appears to vary with 
its position; if it lies on the centre of the spindle towards 
one pole, it passes up with the chromosomes and is included 
in the daughter-nucleus (fig. 14). More frequently, however, 
it lies towards the equator of the spindle; in this case it is 
omitted from both danghter-nuclei (fig. 15). Such omitted 
vesicles shrink to dark dots and can sometimes be detected 
near the cell-wall of 2-celled stages (fig. IG). 
