m for the
purposes of nourishment, protection, and education. In the matter of
the tail, for instance, already noted, the individual rabbit incurs the
disadvantage of conspicuousness for the rear, in order to further the
safety of the young.

Section 137. The female organs of reproduction are shown in
Sheet 10. The essential organ is the ovary (ov.), in which the ova
(eggs) are formed. Figure 3 gives an enlarged and still more
diagrammatic rendering of the ovary. There is a supporting ground
mass, or stroma, into which numerous bloodvessels and nerves enter
and break up. The ova appear first as small cells in the external
substance of the ovary (as at 1), and move inward (2 and 3),
surrounded by a number of sister cells, which afford them
nourishment. At (4) an ovum with its surrounding group of cells is
more distinct and near the centre of the ovary; a fluid is appearing
within the ovisac as the development proceeds. (5) is a much more
mature ovisac or Graafian follicle.

Section 138. The ovum (ov.), is now large, and its nucleus and
nucleolus (the germinal vesicle and spot) are very distinct. The wall
of the follicle consists, in the mammal, of several layers of cells, the
membrana granulosa (or "granulosa" simply); the ovum lies on its
outer side embedded in a mass of cells, discus proligerus,
separated from actual contact with the ovum by a zona pellucida.
The ripening follicle moves to the surface of the ovary and bursts, the
ovum falls into the body cavity. In Figure 2, a ripe Graafian follicle
(G.F.), projects upon the ovary.

Section 139. The liberated ovum is caught up by the funnel-shaped
opening of the Fallopian tube, which passes without any very
conspicuous demarcation into the cornu uteri (c.ut.) of its side; the
two uterine cornua meeting together in the middle line form the vagina
(V.), which runs out into a vestibule (vb.) opening between tumid lips
to the exterior. The urinary bladder (ur.b.) also opens into the
vestibule, and receives the two ureters from the kidney.

Section 140. In the male we find, in the position of the female uterus,
a uterus masculinus (u.m.). The essential sexual organ is the testis
(T.), a compact mass of coiling tubuli, which opens by a number of
ducts, the vasa efferentia, into a looser and softer epididymis (ep.),
which sends the sexual product onward through a vas deferens (v.d.),
to open at the base of the uterus masculinus. The urinary bladder and
ureters cor