366 DR FOULIS ON THE DEVELOPMENT OF THE OVA, ETC. 
these fibres are direct prolongations of the protoplasm surrounding the nuclei 
of well-formed connective tissue corpuscles. The nucleus of a connective tissue 
corpuscle at first often appears as a solid or semisolid body, but it may become 
distinctly vesicular, like the nucleus or germinal vesicle of the ovum. 
It will be observed that, in my description of the germ epithelium and of the 
development of the ova, I have avoided the use of the word cell, and substituted 
the term corpuscle, and my reason for not using the term cell in connection with 
the germ epithelial corpuscles is, that the germ epithelial corpuscles, and the 
so-called columnar epithelial cells which line the pleuro-peritoneal cavity of 
the embryo, are nuclei which have a thin film or investment of protoplasm round 
them. These nuclei are the homologues of the nuclei of the peritoneal epithe- 
lial cells. When a corpuscle divides, each half of the nucleus carries with it a 
small investment of protoplasm. The protoplasm round the nuclei varies con- 
siderably in quantity during the development of the germ epithelial corpuscle. 
The term cell is employed in somewhat different significations by biologists. 
Some, for example, holding that a cell must have a definite wall, whilst others 
look upon the wall as of secondary and minor importance, and hold that a cell 
essentially consists of a nucleated mass of protoplasm. The germ epithelial 
corpuscles and connective tissue corpuscles do not possess a cell wall. When 
once a cell wall has formed round a corpuscle, the nucleus and cell contents — 
may divide. The cell wall does not participate in the division, but incloses the 
products of the division. The cell wall may burst and liberate the contents of 
the cell. 
Every egg cluster is included in a mesh of the stroma. This mesh consists, — 
of connective tissue corpuscles and minute blood-vessels whose walls consist of 
such corpuscles. Delicate processes of this vascular young tissue from the wall 
of the mesh grow inwards among the corpuscles which are developing into 
primordial ova. On tearing to pieces small fragments of a 74 months’ feetal : 
ovary, and placing the debris in a little water under the microsrope, we find small 
groups of primordial ova (figs. 25, 26), and single individuals (figs. 27, 28, 29), 
which have been torn away from the egg cluster, and in connection with some 
of the largest of these we frequently find fusiform corpuscles (figs. 28, 29, 2, 2) 
similar to those which lie in the walls of the meshes. In good specimens the 
fusiform corpuscles are found lying in indentations in the yelk substance (figs. 
28, 29) which surrounds the germinal vesicle of the primordial ovum, and 
sometimes we see primordial ova whose yelk is indented in many places, but 
the fusiform corpuscles have been displaced from these indentations. No zona — 
pellucida is found round such young primordial ova. The connective tissue 
corpuscles must therefore be in contact with the yelk of the primordial ova. 
Directing our attention to the youngest follicles, we find these vary in size, 
but in every case the young ovum fills up the whole follicle in such a manner 

