proligerus, consists of a lenticular mass of protoplasm
(Fig. 4, c), imbedded in which is a globular or ellipsoidal
body (Fig. 4, x), about 310% in diameter, called the
germinal vesicle. This has a delicate wall, and its con-
tents are clear and fluid in the fresh state, but become
granular upon the addition of reagents,


1] THE OVARIAN OVUM. 18


The rest of the ovum is known as the yolk. This
consists of two elements, the white yolk- and the yellow
yolk-spheres, which are distributed respectively very
much in the same way as in the laid egg, the yellow
yolk forming the main mass of the ovum, and the white
yolk being gathered underneath and around the disc
(Fig. 4, w. y), and also forming a flask-shaped mass in
the interior. The delicate membrane surrounding the
whole is the vitelline membrane.
The youngest ova in the ovary of a fowl, in common
with those of all other animals, present the characters
of a simple cell. Such a cell is diagrammatically repre-
sented in Fig. 5.
It is seen to consist of a naked protoplasmic body
containing in its interior a nucleus—-the germinal vesi-

cle—which in its turn envelopes

Fie. 5, a nucleolus—constituting what is
known as the germinal spot.
Such young ova are enclosed in
a capsule of epithelium, named
the follicle or follicular mem-
brane, and are irregularly scat-
tered in the stroma of the ovary.
