112 BOARD OF AGRICULTURE. 
expert, unless examined with a powerful microscope. This is 
one reason why deaths so frequently occur from eating pork 
filled with this parasite. When recently introduced into pork 
or human flesh, the little worms are free and coiled up among 
the muscular fibres, but after four or five weeks they become 
enclosed in minute, whitish, elongated, oval or roundish cysts 
or capsules, due to the irritation and inflammation that they 
cause by feeding and moving (Fig. 76). After a year or more 
these cysts become calcified by a deposit of carbonate of lime 
in the membrane, and at this time are visible to the 
eye as minute specks, about the size of hemp-seed, scattered 
through the muscles. When enclosed in the cyst, the worms 
become dormant, and though they may live for years, and 
even some weeks after the death of their host, they can do no 
further harm unless swallowed by man or some animal. Each 
cyst contains a little slender worm about one twenty-fifth or 
one thirtieth of an inch long, and one seven hundredth thick, 
coiled up in two or three 
turns. The cysts average 
about one eightieth of an 
inch long and a hundred 
and thirtieth thick. 
If pork or other flesh 
containing these worms, 
either free or enclosed in 
cysts, be eaten by man, 
they become liberated in 
the stomach, and, en- 
tering the intestine at- 
tach themselves to its soft 
lining, and there, sur- 
rounded with abundant 
food, they grow very rap- 
idly and become mature, 
with fully developed sex- 
ual organs, in two days. 
Figure 76—A small piece of human muscle containing encysted young of 
Trichina spiralis Owen, enlarged. forty five diaaytess. From Hearth and Home, 
after Leuckart. 
