OVUM IN THE CAPE AND NEW ZEALAND PERIPATUS. 5 
In addition to the minute yolk-spherules scattered through 
the protoplasm, there are a few larger bodies lying just below 
the shell, which stain deeply, have a homogeneous structure, 
and are probably of a yolky nature. The cells of the lower 
end of the stalk have begun to grow round the outside of the 
egg so as to forma follicle, which at this stage extends round 
about one third of its circumference. 
The nucleus, as is shown in fig. 6, next becomes irregular 
in outline, and is thrown into folds, which project into the sur- 
rounding protoplasm. These projections, with depressions 
between them, occur all round the nucleus. This change in 
the nucleus is probably the forerunner of its total disappear- 
ance, which in the next stage will be described as having dis- 
appeared, though I have not been able to observe the further 
steps in the process in this species. In P. Balfouri, how- 
ever, I have a further stage in its disappearance, in which the 
nuclear wall is completely lost, the position of the nucleus being 
indicated by a dense mass of protoplasm, which at its edges is 
continuous with the loose protoplasmic reticulum of the egg, 
and which contains in its centre some irregular chromatic 
particles: this condition is shown in fig. 7. By a still further 
diffusion and breaking up of this dense mass of protoplasm, it 
is easy to conceive how the nucleus and even its former 
situation might become invisible. 
In the next stage the nucleus is invisible, and the follicle 
completely surrounds the egg, consisting of a layer of flat cells 
which closely adhere to the eggshell; just within the egg- 
shell a few irregular, rather deeply-staining aggregations are 
present in the protoplasm of the ovum. These may be the 
remains of the nucleus which have become scattered through 
the egg, since no such aggregations are present in the former 
stage in which the nucleus itself was visible. 
The next stage is shown in fig. 8. It differs from the last 
only in the fact that the follicle does not adhere to the egg- 
shell, but is separated from it all round, so that the ovum lies 
loose in a hollow vesicle, which is attached to the ovary by a 
long thinstalk. At this stage the cellular nature of the follicle 
