450 THOS. H. MONTGOMERY jr., 
parallel to the long axis of the cell); thus each large epithelial cell 
shows a basal, coarsely vacuolar cytoplasm around the nucleus, on 
this follows a very finely-alveolar cytoplasmic portion, and upon the 
latter a cuticulated cytoplasm, which increases in density terminally 
on account of the convergence of its fibres. Such a structure of the 
cloacal epithelium, which is found only at the most anterior end of 
the cuticular cloaca, passes posteriorly by gradual stages (Fig. 54, 
Pl. 40) into the hypodermal-like epithelium which lines the inner sur- 
faces of the tail lobes (Cl. Epi Fig. 36, Pl. 39; Figs. 71—73, Pl. 41). 
In other words, the further removed from the cloacal aperture, the 
greater is the difference from the external hypodermis, throughout this 
extent only the outer homogeneous cuticula remaining uniform. It is 
very probable that this gradation of cuticular structure corresponds 
to a gradation in final perfection of the cuticula: that most posteriorly 
is found a completed cuticula sharply demarcated from the cytoplasm 
beneath, more anteriorly a cuticula still in process of formation and 
hence not sharply delimited from the underlying cytoplasm. And if 
this be true, the process of cuticularisation would be as follows: the 
cuticular substance is first deposited in the greater portion of the 
cell body distal to the nucleus; its further development consists in its 
gradually becoming condensed near the surface of the cell, and be- 
coming sharply delimited from the cytoplasm. Here is then one region 
in which the process of cuticularisation may be followed in the adult 
organisation. 
The cuticular region of the cloaca is enveloped upon all sides by 
large-celled parenchym (L. Par Figs. 71—73, Pl. 41), the small-celled 
parenchym not extending posterior to the glandular cloaca. The 
parenchym is so closely united with the wall of the cloaca that it 
cannot be dissected off of the latter. 
The ova. In the ovaries of the individuals examined all the 
ova are ovocytes of the first order, and have attained their full size. 
The nucleus '(N Fig. 69, Pl. 41) is spherical, with a faintly-staining 
nuclear sap which in the resting stage shows no trace of a chromatin 
reticulum, and one large “nucleolus”, which stains with both cytoplasmic 
and chromatin stains. Immediately around the nucleus is a zone of 
rather coarsely vacuolar cytoplasm, the alveoles arranged in concentric 
lamellae; then a zone of yolk substance (Y%), in the form of irregular 
spherules of various dimensions; and most externally a zone almost 
free of yolk and of a finely-alveolar structure. No sign of a centro- 
some or attraction sphere was to be seen. Just as the ova enter the 
