DEVELOPMENT OF THE CAPE SPECIES OF PERIPATUS. 181 
The reticulum which connects the endoderm masses is shown 
—highly magnified—in fig. 7, Pl. XII. It lies immediately 
beneath the egg-shell and consists of pale, hyaline strands, 
which at the nodes spread out into flat expansions. The strands 
contain a small number of strongly refractile globular bodies. 
This drawing was made from an uninjured ovum preserved 
in sublimate and acetic acid. The reticulum connecting the 
ectoderm cells is shown in Pl. XIII, fig. 12, made from an 
ovum of the same age and prepared in the same way as the 
last. This drawing represents one corner of the ectoderm 
patch ; three whole cells and parts of three others are repre- 
sented, and they are all seen to be connected by a loose reti- 
culum. The protoplasm immediately round the nucleus has a 
granular appearance owing to the closeness of the reticulum. 
The connection between the ectoderm patch with the larger 
endoderm masses, as seen with a lower power, is shown in 
fig. 9, while fig. 6 represents two small endoderm masses con- 
nected together by, and giving off in all directions, fine strands 
as seen under a higher power. 
The endoderm masses now begin to draw together (vide figs. 
10—13, Part 1), and forma ring-like mass applied all round 
the edge of the ectoderm patch. ‘This ring-like mass is thicker 
at each end of the ectoderm disc than in the centre (Part 1, 
fig. 12), where, indeed, it is sometimes interrupted (Part 1, 
fig. 13). Pl. XIII, fig. 16, represents a transverse section 
through the edge of an ovum at this stage. 
The process of drawing together of the endoderm masses is 
still further continued and the ectoderm cap becomes bent 
round the concentrated solid mass so formed (Part 1, fig. 15). 
Pl. XIII, fig. 20, represents a transverse section through an 
ovum at a slightly later stage, in which a cavity, the future 
mesenteron, has begun to appear. 
The ectoderm cap now gradually (Part 1, fig. 18) grows round 
the endoderm mass, and almost completely encloses it. The one 
unenclosed point persists as the blastopore (Part 1, fig.20). While 
this process has been taking place the cavity in the endoderm 
mass has become larger, and on the completion of the process 
