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 Ei ure 76> 



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 spircdis Owen, enlarged forty-five diameters. From Hearth and Home, 

 after Leuckart. 



