TRICHINOUS INFECTION OF MAN AND ANIMALS. 167 



The adult female varies from three to four millimeters* in length, 

 with the vulva situated near the end of the anterior fifth of the body, 

 as represented at Fig. 5. There is but a single ovar3% and the many 

 ovules are plain to be seen through the smooth integument in vari- 

 ous stages of development. 



The sexually mature female is one-eighth of an inch in length, 

 while the male is only about two-thirds that size. The female is 

 ovo-viviparous, and thus brings forth its young alive, as seen at Fig. 

 4 on the plate. The yonng trichinae begin at once to migrate from 

 the bowels and perambulate the entire system of voluntary muscles, 

 as portrayed in the circular figure. At last they become encysted, 

 and there remain forever at rest, until the^^ perchance shall have 

 been eaten b^' some other animal, when they in turn will be set free, 

 and thus complete a zoological c^xle of existence. 



It should be remembered that it is in the encysted state, as seen in 

 2 and 5, that the trichina is transported from one flesh-eating ani- 

 mal to another. Pigs are not born with these entozoa, but get them 

 in some kind of food, probably from the flesh of rats and mice, and 

 when once swallowed by the hog or other animal the gastric juice, in 

 the process of digestion, soon dissolves this albumino-cretaceous 

 cyst, when the parasite will be liberated from its prison life, and in 

 a few davs become a full-grown worm, within the stomach and in- 

 testines, ready to propagate its countless young. 



The red voluntary muscles, says Dr. Thudichum, are the "prom- 

 ised land of the trichinae." There the}' migrate, grow, and enshrine 

 themselves. Although the young trichinae, on the seventh da}- and 

 later after infection, are found in almost all the organs of the body, 

 yet the}' do not grow or become encapsuled in any other tissue. The 

 trichinae, according to his observations, arrive in the muscular tissue 

 with the blood. The diameter of the smallest capillaries in the 

 muscles is much less than the diameter of the young trichinae, so 

 they are certain to be arrested. They then penetrate the single or 

 double coats of the muscles, and are at once in the interstitial spaces 

 between the muscular fibers. Many trichinae unquestionably never 

 enter the sarcolemma, and become encysted, but when they do the 

 fibers become permanently destroyed. At the end of the third week 

 after immigration, the inflammatory irritation of the muscular fiber 

 has reached its highest point, the trichina is nearly full grown, and 

 becomes fixed to the spot where it is to be encapsuled. Several of 



*.09 to .11 of an inch (nine to twelve hundredths of an inch.) 



