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The oesophagus is divided into two distinct parts. The cephahc part is rather short
and slender and suddently passes into the other half which is conspicuously thicker
and longer with fairly uniform width throughout the length, and only increasing in-
conspicuously in the hindmost part. The proportion of the length in the two halves
is about 1 to 6. In an oesophagus, the whole length of which measured 2,7 mm. the
diameter was found to be 26,4 (x in the slender part whereas in the thicker half a little
anterior to its passing into the chylus-intestine the diameter was found to be 52,8 fi or
exactly twice the size of the front part.
The length of the oesophagus differs conspicuously as far as the two sexes are
concerned. In a female specimen the length of which was 6 ctm. the oesophagus
measured 7 mm, coming thus to 7’^ of t^e whole length of the worm. In a male
of V-h ctm. the oesophagus measured 2,8 mm. or about ^4 of the length.
Round the middle of the front part of the oesophagus the nerve-ring is very di-
stinct both in the fully developed worm and in the larva (see PI. III fig. 17, and
PI. IV fig. 28). In the male specimen of l^/s ctm. mentioned above, the diameter of
the nerve-ring measured 45 ^u. In optical sections the central part of the nerve-ring is
seen to consist of a granulated substance surrounded by an apparently homogenous
coat, which presents itself exceedingly thin on the side facing the oesophagus. Similar
spurs of sarcoplasma as described by Looss in the Filaria loa are found reaching from
the muscular layer towards the nerve-ring (fig. 18).
The oesophagus is as usual marked off from the chylus-intestine by a constriction,
the chitin-intima, however, being traceable somewhat further down.
As far down as this chitin-intima reaches the intestine presents a peculiar differ-
entiation with faint transversal striæ, probably consisting of muscular tissue. Gaudal
to this part some conspicuous intestinal valves are observed, sometimes arranged in two
rows as may be seen in the fig. 23.
On the whole, the chylus-intestine is but slightly developed, its width being almost
corresponding to that of the thin front part of the oesophagus. Most frequently it
appears as a fme line throughout the worm; only its hind part is sometimes rather
sinuous and the lumen here somewhat more dilated than is the case in the rest of
the intestinal canal. Rectum decreases in width (fig. 19). The anal musculature is well
developed. The intestine in the female opens at a distance of 210 fi from the
tip of the tail, the shape of which is regularly conical with rounded point. The
tail, as well as the front part of the worm, shows a great power of contraction.
On the specimen, pictured on the fig. 19, the tail has fairly its natural shape
and length; when contracted it will only present half the length and become thick
and folded, often ventrally bent. In the male, which has a large bursa and only
one aperture for the intestinal and genital duet, the anus is situated at a distance
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