F. H. Stewart 
165 
Excretory system. The single renette 1 cell (Fig. 1, R) lies between the left lateral line and 
the intestine, at a level midway between the end of the salivary gland and the commence¬ 
ment of the gonad; it is somewhat difficult to recognise; in unstained preparations it has 
the appearance of a spherical space containing a small highly refringent sphere, which in 
stained specimens proves to be a chromatin mass. I have not succeeded in tracing the duct 
between the renette cell and the excretory pore; this aperture is situated behind the 
posterior margin of the nerve ring at a distance varying slightly in different specimens, but 
averaging 0-02 mm., equal to rather more than the length of the oesophageal bulb; this 
position markedly behind the nerve ring is of systematic importance (vide supra); the 
excretory duct contains a substance which stains with haematoxylin, giving a curious 
appearance, as if a spine were projecting through the cuticle. 
There are no caudal glands. 
The reproductive system in the female consists of two tubular sacs (Figs. 1 and 14, OE, V A, 
VP) extending forward and backward from the vulva; the anterior end of the anterior sac 
contains the ovary (Figs. 1 and 14, 0); the ova (Fig. 1, OV), as they pass backward increase 
in size and become elongated oval in shape; the wall of this part of the sac consists of a 
fairly robust endothelium, which, in those places where it contains nuclei, bulges into the 
lumen and compresses or separates the ova (Fig. 1, OE); the nuclei have a characteristic 
circumvallate appearance. The structure of the uterus (Fig. 1, U) is difficult to analyse; it is 
closed at its posterior end where it joins the anterior vagina by a sphincter (Fig. 1, SPH). 
It is probable that fertilisation and formation of the shell occur in the anterior vagina. 
Marcinowski (1910) describes a shell gland in Cephalobus, but it should be remembered 
that Schneider (1866, p. 285) proved that the shell of nematode eggs is secreted by the egg 
itself, and not by the wall of the oviduct. The anterior vagina extends from the sphincter 
to the vulva; its walls are of irregular thickness, and do not contain the typical nuclei of 
the ovarian sac; the lumen is occupied by a mass of spherical spermatozoa. The retrovulvar 
portion of the reproductive tube consists of the posterior vagina alone, which resembles the 
anterior vagina in length and other respects, but is a caecum; the vaginae function as 
receptacula seminis. (For development in the larva, and early fertilisation, see Sect. V 
below: for comparative anatomy, p. 172 (3).) The vulva is a transverse slit situated j^jths 
of the body-length from the head. 
Male reproductive organs (Figs. 2 and 3). The single testicular tube has an endothelial 
wall, like the ovarian; posteriorly it joins the intestine to form the cloaca, and is here closed 
by a valve-like projection of the ventral wall. The spicules (Figs. 2 and 3, SP) are very 
broad, curved and hollow, the posterior margin is much thickened, the anterior margin is 
the structure described and figured by Ritzema Bos (1893) as the accessory piece; the two 
spicules are very closely apposed; there is no accessory piece. The tail of the male (Fig. 2) 
is sharply curved, the ventral surface flat, with one poorly-defined papilla, post-anal, median 
ventral (Fig. 2, P); in mounted specimens there is sometimes an appearance of a bursal 
membrane, which is probably artificial, but the flattening of the ventral surface must 
produce a ridge along each lateral line which forms the rudiment of a bursal membrane. 
V. A. PHYLLOPHAGUS. THE EGG, AND LARVAL DEVELOPMENT. 
The egg (Figs. 15 and 18) is sausage-shaped, 0-085 x 0-023 to 0-095 x 0-022 mm. The 
shell is thin and unsculptured, the ovum when first laid unsegmented. I have not observed 
segmentation or embryonic development. 
Larvae. Molz (1909) gives the length of the newly-hatched larva as 0-16-0-18 mm. and 
its breadth 0-01 mm. (a 16-18). The youngest larva which I have seen (Fig. 17) measured 
0-22 x 0-015 mm. (a 14-7), the spear 0-012 mm.; it was found in the leaf axil of a groundsel 
on the 28th day after infection, together with adults and eggs, and had recently hatched 
1 Cf. p. 172(2). 
