MALARIA EXPEDITION TO NIGERIA 7 
Parasites of birds and mammals. In mammals, different species live in the 
bladder of the fox and wolf, and of the cat, and in the trachea of the fox and martin. 
In some species two, three, or lour males live within the uterus of the female. 
Genus Trichina. Small capillary worm, slightly swollen posteriorly. Male 
has two conical appendages posteriorly forming a sort of copulatory bursa. There 
is no spicule. Female is viviparous. Vulva situated in anterior fifth of the body. 
A single species T. spiralis only known. 
Life history. The adults, male and female, live in the intestine of man 
and other mammals. The female produces very numerous eggs which give rise to 
embryos in the body of the uterus. These embryos bore through the intestinal 
wall of their hosts, and make their way all over the body, coming to rest most usually 
in the muscles. Here they generally pierce the sarcolemma and become encysted 
inside the muscle fibre. The larvae may here remain dormant for many years, and 
undergo fatty or calcareous degeneration. When trichinised meat is eaten, unless 
thoroughly cooked, the cysts are dissolved and larvae set free, and become sexually 
mature in three or four days ; again producing ova and embryos which bore through 
the intestinal wall. 
IV. Filariidae 
Long filiform worms ; mouth with two lips or without lips — often have 
papillae, and sometimes a buccal capsule. Males have a tail generally incurved, have 
one or two unequal spicules, four pairs of pre-anal papillae, and sometimes an 
unpaired one as well. Females have double ovary. Vulva is situated towards the 
anterior part of the body. Many are ovoviviparous. 
Genera : Fi/aria, Icbtbyonema, Hystrichus, Spiroptera, Disparagus, and others. 
Genus Fi/aria. See next chapter. 
Genus Icbtbyonema is confined to fishes. Male is very minute, and the 
female partly degenerate. No anus, no external generative organs. Uterus fills the 
entire body cavity. 
Genus Hystrichis. The anterior part of the body is armed with spines. 
Male has a bell-shaped bursa, and very long spicule. Vulva is near the anus. 
The parasite lives between the walls of the oesophagus and gizzard of some 
birds — palmipeds (duck, swan). 
Genus Spiroptera. These can only be distinguished from the Filariae by two 
features — the body is generally shorter and thicker, and the vulva is ordinarily nearer 
the mouth. Their specific name is taken from the tail of the males, which is rolled 
into a spiral and furnished with lateral membranous expansions. 
Several species are described generally met with in tumours of the oesophagus, 
stomach and intestines of horses, asses, mules, pigs, dog, wolf, etc. S. reticulata has 
been found in the cervical ligament, in periarterial tissue, between muscles and 
tendons, and in other positions in the horse. 
