DEVELOPMENT OF THE OAPE SPECIES OF PERIPATUS. 187 
directly into the former. The pale nuclear reticulum is 
also similar to the extra-nuclear reticulum, differing only in 
intensity of staining. 
It is also directly continued into the nuclear membrane and 
septum. The apparently isolated, deeply-staining bodies, both 
globular and branched, are also, as I have said, continuous 
with the pale reticulum; so that this nucleus may be described 
as consisting of a portion of the spongework of which the 
ovum is composed, the nuclear protoplasm differing only from 
the external protoplasm in the fact that the staining matter is 
aggregated into special parts of the spongework instead of 
being uniformly diffused throughout the latter as in the 
extra-nuclear protoplasm. The apparent nuclear membrane is 
simply part of the protoplasm at the junction of the modified 
(nuclear) and unmodified (cell-substance) part of the proto- 
plasmic network. 
The question now presents itself; why do parts of the 
nuclear spongework appear more deeply stained than the rest ? 
Either the parts thus staining are of greater mass than the 
rest, extending through the whole thickness of the section, 
while the pale strands are so fine that several of them, separated 
by the spaces of the meshwork, lie above one another in one 
transverse section ; or there is a special chromatic substance, 
distributed at intervals in the intra-nuclear spongework. If 
the former is the correct answer the difference in colour 
between the pale and stained parts of the network is of the 
same nature as the difference in the colour of blood or another 
coloured fluid when viewed in a thick or in a thin layer. 
Though there may be something in this way of looking at 
the deeply staining parts of the nuclear spongework, I do not 
think that it entirely explains the matter. 
It may here be mentioned that the meshes of the extra- 
nuclear reticulum immediately around the nucleus are much 
smaller than in parts remote from the nucleus, so that in a 
transverse section several strands will lie one above the other 
in even the thinnest section, while away from the nucleus, 
where the meshes are coarser, a smaller number of strands will 
