322 THE CEPHALOPODA 
neighbourhood. ‘This follicle is nourished by an important vascular 
supply, and its surface of contact with the ovum is increased by the 
formation of equatorial and meridional folds (Fig. 285, fo) which 
penetrate into the substance of the ovum and secrete the vitellus. 
This vitellus forms an increasingly large part of the mass of the 
ovum and pushes the formative protoplasm and 
the nucleus up to its narrower pole opposite to 
the peduncle of attachment. 
When mature the ovum acquires a chorion 
with a micropyle, escapes by dehiscence of its 
external envelope into the coelomic cavity or 
genital capsule (Figs. 252, coe; 278, g.c), and 
passes into the genital duct. In its passage 
through the oviduct the egg traverses a more 
or less voluminous glandular enlargement of the 
Be ar eet re duct, situated on the wall of the genital capsule 
follicle; vi, vitellus. itself in Naudilus, at the middle of the duct in 
(After Huxley and Pel- E 
seneer.) the Octopoda, near the free extremity of the duct 
in the Decapoda. This glandular enlargement is 
formed of two distinct portions in the Octopoda (Fig. 278, 0.g) and is 
feebly developed in Argonauta, whose eggs are protected by the 
external shell. In addition to the true oviducal glands there are 
other accessory glands, unrelated to the genital ducts, in female 
Cephalopods. These are differentiations of the wall of the pallial 
cavity, and occur on the pallial wall in Nautilus (Fig. 270, n), but 
on the somatic wall in the Dibranchia. In the latter order they 
form two distinct masses, one on either side of the rectum; whereas 
in Nautilus they form a continuous mass (Fig. 276, g.n). In certain 
Oigopsida (Hnoploteuthis, Cranchia, Leachia) and in the Octopoda 
these organs are absent. In the Dibranchia these “ nidamentary ” 
glands open near the genital orifice, and are generally accompanied 
by a second pair, as, for example, in Sepia: they produce the 
external envelopes of the eggs, formed by an elastic substance which 
hardens rapidly on contact with the water. 
In the male, the testis is the specialised portion of the coelomic 
wall from which the spermatozoa are developed (Fig. 286, III): its 
structure is comparable with that of the ovary. The spermatozoa, 
when mature, pass through an orifice into the genital capsule 
properly so called, and thence into the spermiduct which originates 
from the wall of this capsule and opens externally into the pallial 
cavity, on the right side in Nautilus (Fig. 275, pe), on the left side 
in the Dibranchia (Fig. 286, VIIL). Certain glandular pouches and 
a terminal reservoir are found on the course of the spermiduct. 
Nautilus has only one glandular pouch, but in the Dibranchia 
there are, as a result of specialisation, two pouches: (1) the 
vesicula seminalis, which is a simple enlargement ; (2) the prostate. 
Fig. 285. 
