THE TRICHINA. 127 
by six tubercles. Hustrongylus papillosus Diesing, accord- 
ing to Wymun, lives coiled up in the brain of the anhinga, 
or snake-bird of Florida. £. buteonis Packard was found 
living under the eyes of Buteo Swainsoni, and EL. chordeilis 
Packard in the brain of the night-hawk. Dochmius duoden- 
alis Dubini lives in the small intestine of man. 
Trichocephalus dispar Rudolphi (Fig. 86) lives in the 
cecum of man, with the smaller anterior part of the body 
buried in the mucous membrane. 
The most formidable round worm is the Trichina spiralis 
Owen (Fig. 87). The body is regularly 
cylindrical, tapering gradually from the 
posterior end to the head. The end of the 
body of the male is without a spiculum, but 
with two conical terminal tubercles. It is 
1.5 millimetres long. The female is 3 mil- 
limetres in length. 
Viviparous females begin about eight days 
after entering the intestine of their host to 
give birth to the larva, which bore through 
the walls of the intestines of their host, 
passing into the body-cavity, and partly in- 
to the connective tissue, and also, by means 
ot the circulation, into the muscles. In 
about fourteen days the worm coils up 
spirally in a cyst (Fig. 87), which eventu- 
; ey Fig. 87.—Trichina 
ally becomes calcareous and whitish. When encysted. im human 
the flesh of the pig, infested by the encysted Taeg’: Stes Pouce. 
larve, is eaten by man, the young worms 
are set free in the stomach of their new host, and in three 
or four days become sexually mature. The female Trichina 
is capable of producing a thousand young. The original 
host of the Trichina is the rat; dead rats are often de- 
voured by pigs, and the use of raw or partially cooked pork 
as food is the means of infection in man. 
Another worm, occasionally parasitic in sailors and resi- 
dents of the East Indies, is the Filaria medinensis Gmelin, 
or Guinea-worm. It is remarkably long and slender, some- 
times over two fect in length. The female is riviparous, 
