120 ELEMENTS OF APPLIED MICROSCOPY. 
8. The Microscopic Examination of Pork for Trichina. 
—The disease known as trichinosis is, like diphtheria and 
typhoid fever caused by a parasitic micro-organism, 
although the parasite belongs to a very different group. 
Trichina is a minute worm, barely visible as a.speck to the 
naked eye, which bores its way into the muscles of swine 
and there encysts itself in a calcareous nodule. If such pork 
be eaten, imperfectly cooked, the limy cyst is dissolved; 
the worms emerge and reproduce, and a myriad of their 
progeny penetrate the tissues of the body, causing high 
fever and, sometimes death. If the patient recovers from 
this crisis, the worms encyst themselves in the muscles 
and produce no further serious difficulty. 
In America, trichinosis is rare in man, although some 
2% of swine are affected with it, because pork is more 
or less thoroughly cooked before eating. In Europe, 
however, where pork products are eaten almost raw, the 
danger is serious and must be met by preventing the 
distribution of trichinous swine flesh. Elaborate govern- 
ment systems of, meat inspection have been instituted in 
many countries; in Prussia, for example, over 25,000 
officials are employed for this purpose. In the United 
States the Department of Agriculture for some years 
maintained a bureau of meat inspection which examined 
all pork intended for foreign export and interstate com- 
merce, employing a large corps of microscopists. 
Samples of pork to be examined for Trichina are taken 
from the diaphragm or other muscles and cut in pieces 
about an inch by half an inch in size. One such piece 
is then placed between two slides of heavy glass, mounted 
