PARASITES OF ANIMALS. 119 
eating slaughter-house offal. It is possible, also, to infect 
hogs and other animals by means of the mature female 
Trichine that have been discharged from the intestines of 
men or animals, before all the young worms contained in their 
uteri have been born. Therefore hogs may obtain this, as 
well as the larve of the tape-worm of man and many other 
parasites, by being kept in places where they have access to 
manure, as is too often the case. Cats, rats, mice, rabbits, 
Guinea-pigs, young dogs, and various other animals may be 
infected, but adult dogs, like old hogs, are not nearly so likely 
to become infected as the young. Although lambs, calves, 
and horses may be infected by forcing them to eat trichinous 
meat, it is probable that they seldom or never become infected 
naturally. 
Trichocephalus dispar Rudolphi. Figure T7. 
This is a small round-worm, living in the human intestine, 
and remarkable for its long, very slender, filiform neck, which 
Figure 77.18. about two-thirds of the entire length. The 
( male grows to the length of one inch and a 
half, aud the female to two inches. The sur- 
face of the body appears smooth to the naked 
eye, but when magnified, a longitudinal band of 
minute, wart-like papilla is seen on one side. 
The male has the posterior end of the body 
spirally curved, with a single spicule, which is 
emitted from the extremity of the body, and is 
enclosed in a short, tubular sheath, that is cov- 
ered with minute recurved spinules. The female 
“has the posterior end of the body nearly straight 
s ’ and bluntly pointed (Figure 77). The genital 
orifice is situated at the origin of the neck. The eggs are 
elliptical, with a small projection at each end, and are z}5 to 
xhy of an inchlong. They are discharged from the human in- 
testine before the contained embryos are fully developed. If 
kept in water for six months or more they hatch, liberat- 
ing a minute embryo 343 of an inch long, which tapers 
from behind toward the head. 
Figure 77.—-Trichocephalus dispar ; a, female, natural size; 6, posterior end, en- 
larged. From Guerin. Digitized by Microsoft® 
