M. ANANTARAMAN 119
third stage has somewhat shifted to the posterior end on the ventral side, is
longer and is composed of more cells, about 8 in number. It is a cylindrical
structure, shows a beaded appearance and ends somewhere in front of the
rectal ligaments. Lying free in the coelomic cavity between the ventral body-
muscles and the intestine it awaits further development into uterus, ovary, etc
In the potential male, the tail does not extend from the anus as much as
in the female, and ends abruptly with a truncated appearance on the ventral
side. The tip is swollen as a knob as in the other. The internal genitalia are
in two sets, one a linear and narrow cellular organ, in the ventral region of
the coelom between the intestine and the body-wall and beginning from behind
the posterior end of the cervical gland runs till the rectal region to ultimately
grow into testis, etc. The other is a cluster of cells wedged between the dorsal
coelomic wall and the rectum and destined to be the precursor of the spicular
structures of the adult.
Development of the larva does not progress any further unless the larva
pierces the nodule ('secondary parasitic migration') and emerges into the
lumen of the intestine. This period of intra-nodular life seems to be influenced
by various conditions and therefore differs with individuals. In calf No. 3
which was killed on the 7th day after a drench of 3000 infective larvæ, the
fourth-stage larva had migrated into the intestinal lumen from the nodules,
and in calf No. 5 which was destroyed on the 9th day after an intake of larvæ,
a few fourth-stage larvæ were observed to have travelled to the caecum and
colon on that day, and naturally emergence should have been sometime before
that. It can therefore be concluded that the larvæ normally leave the nodules
on the eighth day.
There was an instance of aberrant nodular life in calf No. 11 about 2000
infective larvæ were orally administered to this animal on 19 August 1940
and the animal died on 22 October 1940, nearly two months after. The
autopsy revealed that of the 2000 larvæ more than a hundred had grown into
adults in 64 days, whereas the rest were arrested in the nodules of the Ileum as
fourth-stage larvæ. The duration of nodular existence is thus seen to be
variable, not only in different calves but for different larvæ of the same lot
as well.
The escaped larvæ continue to be in the fourth-stage for some more days
although the development towards the adult condition progresses rapidly
meanwhile. Figs. 17 and 18 are of the posterior regions of a male and a
female larva recently arrived in the intestine from the nodule. In the male,
the tail has assumed a more truncate appearance and the genital rudiment is
long and is divisible into a posterior thickened region with a number of cells
and an anterior narrow one with a linear set of cells reaching near the cervical
gland. In the neighbourhood of the rectum and dorsal to it is the serially
disposed cells of the spicule-apparatus. In the female, the tail is conical and
tapering and much longer than that of the male. The anus is situated 0.12
mm. from the knobbed tip, and the female genital organ in front of the termi-
nation of the intestine. There is a bulbous structure showing indications of
developing into the future ovijector, from which is an anterior extension of
cells in two rows for a distance of 0.04 mm. the fore-runner of the uterus—and
in a single row of cells appearing like a cord and suggestive of the future
D