H. D.
SRIVASTAVA
407
is in the fundus of the gland, to facilitate feeding. The eggs are passed out
with the faeces and, on being ingested by a suitable intermediate host, the
larvæ reach the infective stage inside its body cavity in about nine to twenty,
eight days (Plate XXXV, fig. 2). A number of invertebrates are known to serve
as its intermediate hosts, such as, ' water flea ', ' sand flea ', several species of
grasshoppers and cockroaches and two species of earth-worms. When an
infested intermediate host is eaten by a bird, the infective larvæ are freed in the
proventriculus and enter the glands of Lieberkuhn. The larvæ attain maturity
in about 90 days. The worms suck blood, but the greatest damage is
done when the young worms penetrate into the wall of the proventriculus,
setting up marked irritation and inflammation, which may prove fatal. The
stomach wall becomes greatly thickened and inelastic from congestion. Con-
siderable emaciation and anaemia are observed in heavily parasitized birds.
Another genus of round-worms—Echinuria—occurs in the oesophagus,
proventriculus, gizzard and occasionally small intestine of the duck, goose,
swan and other aquatic birds. These parasites live in cyst-like structures
which open through minute pores into the lumen of the gut. Each cyst
harbours a surprisingly large number of worms, which discharge their eggs
into the gut. The eggs are voided with faeces and on being swallowed by a
suitable intermediate host, which is a " water flea "—Daphnia pulex—they
hatch and the larvæ reach the infective stage inside its body cavity. The
final host acquires infection by ingesting water fleas harbouring infective
larvæ. In the final host the worms penetrate into the wall of the proven-
triculus or gizzard causing marked inflammation and the formation of nodules.
The nodules are often found to contain bloody fluid or yellowish caseous
matter. They may become large enough to cause mechanical interference
and even obstruction to the passage of food. The wall of the proventriculus
is thickened and the mucosa is covered with a large amount of yellowish
green vicid mucous. The birds lose condition, become dull, feathers are
ruffled, and feeding may become suspended. Sudden death is known to
occur.
In the gizzard of the fowl and turkey occurs a white, slender round-worm,
Cheilospirura hamulosa, which produces tunnels and soft nodules underneath
the horny lining of the stomach. The eggs are passed in the faeces and on
being taken up by a suitable intermediate host hatch in its intestine. Various
species of grasshoppers may serve as intermediate hosts of this parasite.
The larvæ reach the infective stage inside the grasshopper in about 25
days. The final host becomes infected by eating grasshoppers. In the
avian host, the worms force their way through the horny lining of the gizzard,
usually in the anterior part of the organ where the lining is softest. For a
period of 19 days they remain on the surface of the muscular wall,
under the lining. Between the 20th and the 25th day they start to
penetrate the wall and are found with their heads imbedded. Later on in
about 76 days they attain sexual maturity and are located in circum-
scribed nodules with caseous contents. These parasites produce soft nodules