172 Proceedings of the Royal Society of Edinburgh. [Sess. 
rete and Wolffian tubules are seen in the hilum of the ovary. The central 
portion of the cortical zone contains masses of cells which become 
follicle or interstitial cells, i.e. reserve cells, which are derived from the 
oogonia near the periphery. These cells differ in character, showing stages 
of progressive and regressive growth. The follicle cells are derived from 
the oogonia only, and have no relationship with the stroma cells. No 
evidence is found of processes extending from these cells to the oocytes 
which might be taken for food carriers, although it is most probable that 
the growing oocyte derives its nutriment from these cells. Mitotic figures 
are not seen in the follicle cells, their proliferation taking place in all 
probability by direct division. The germ cells in their early stages are 
oogonia when the nucleus is small, oval, and granular, with a nucleolus, and 
a few chromatin filaments and masses. These masses become broken up 
and scattered over the protoplasm and the filaments are more distinct. 
The nucleus becomes spherical, with a well-defined nucleolus ; the chromatin 
is in the form of a reticulum, being beaded in appearance, the centre is 
clearer, and the nuclear membrane has chromatin granules attached to it 
by means of their linin processes. Mitosis takes place among the oogonia, 
and among these larger cells which may be called oocytes of the first stage 
(deutobroque). Some go on to form further advanced stages in the life- 
history of the oocyte. Others remain in a resting stage, or become smaller 
and function as follicle or interstitial cells. Those oocytes which are 
destined for fertilisation have the following stages. 
The chromatin is spread over the nucleus as a fine reticulum like a thin 
spireme, the nucleolus is faint, stage of fine spireme, and is very transitory. 
The filaments become aggregated at one side of the nucleus near the mem- 
brane into the form of a skein of looped threads, some of which appear to be in 
pairs. This skein becomes more dense, until finally the whole of the filaments 
are gathered into a mass of chromatin substance. This mass becomes dis- 
entangled, and the filaments emerge as thick threads, and are spread out over 
the nucleus. The formation of the skein is called the synaptic stage, and is 
a prolonged one, and may be divided into three divisions — (a) where the fine 
paired filaments are entering the skein, ( b ) where all the filaments are in 
the skein, ( c ) where the thick single filaments are emerging from the skein. 
Synapsis is the most important stage of all, as it is during it that the 
filaments become united temporarily by their linin processes. This skein 
is not due to the fixing and staining processes employed in the preparation 
of the sections, as it has been seen without variation in all the types examined, 
and when fixed and stained by different reagents. The nuclear membrane 
is faint in outline ; the nucleolus persists, but is lost sight of in some nuclei 
