ACUTE INFECTIOUS DISEASES. 



are particularly numerous about the ends of the muscle, where it be- 

 comes tendinous, probably because their further progress is obstructed 

 at these points. Trichinae have a particular preference for the muscles 

 of the loins, diaphragm, the intercostal and cervical muscles, and foi 

 those of the eye and larynx. In the extremities, as a rule, " the fur- 

 ther from the trunk, the fewer trichinae in the muscles" (Reny). In 

 the human being, at least, they seem never to enter the muscles of the 

 heart. The wandering of trichinae induces parenchymatous and inter- 

 stitial myositis. The free, emigrating trichinae, which gradually attain 

 the length of one-third of a line, are not visible to the naked eye. At 

 the point where they finally become attached, the irritation they induce 

 leads to a development of the sarcolemma, and thus to the formation 

 of a capsule, which is egg or lemon-shaped. This capsule grows 

 thicker; calcareous salts are deposited in it, and it is the trichinae 

 enclosed by such calcified capsules that are visible to the naked eye. 

 At least two months are required for the formation of a perfect 

 capsule. 



The etiology of the trichina disease in animals is still obscure. Of 

 course the solution of the question, whence come the trichinae in pork ? 

 is very interesting, and of great practical importance. It is probable 

 that they acquire them chiefly or solely by eating trichinous rats. It 

 is well known that pigs not unfrequently eat live and dead rats, and it 

 is also known that rats not only frequently have trichinae, but that they 

 often die of them. 



In the human being the trichina disease results solely from eating 

 trichinous pork. The raw flesh is the most dangerous, hence the dis- 

 ease is proportionately more frequent and more severe in those who 

 have the bad habit of eating raw meat than in others. More fre- 

 quently than in the raw form, pork is eaten prepared in a manner that 

 does not kill the trichinae. Even large pieces of well-boiled or baked 

 pork, which do not show any red spots on being cut, and into which 

 we may easily pass a fork without a feeling of grating, never contain 

 trichinae. But they may exist in roast pork, whose external portion 

 only has been exposed to a temperature of 55 R. [156 F.], while 

 the inner part has not been heated so much, looks bloody, and 

 is somewhat hard and coherent. And even in small pieces of meat, 

 and in the various forms of sausages, if they be cooked for only a 

 short time, the trichinae remain alive in the parts distant from the 

 surface. Trichinae are found especially often after the use of so- 

 called fresh blood and meat sausages, of meat-balls, and similar 

 preparations. Long-continued salting (pickling) of pork, without the 

 addition of water, kills the trichinae even in large pieces ; on the othei 

 hand, numerous trichinae may survive in pickled meat that has oul\ 



