1881.] 



MICKOSCOPICAL JOURNAL. 



43 



power of fifty to seventy-five dia- 

 meters is always to be preferred. 

 The capsules do not always present 

 the same form to the eye of the ob- 

 server ; sometimes they are well 

 elongated ; while at others they are 

 more round, the usual extenuations 

 at the ends being almost entirely 

 wanting. Their average dimensions 

 may be said to be 0.4 millimetre 

 in length, and 0.26 millimetre in 

 breadth. They not infrequently con- 

 tain two, and sometimes three, para- 

 sites. 



So long as the trichinae are in their 

 capsules in the fibre of the muscle, 

 their condition remains unchanged 

 except to die or degenerate after the 

 lapse of a long time ; they make no 

 progress in their development. They 

 have been seen in an active condition, 

 — /. ^., capable of progressive devel- 

 opment under suitable circumstances, 

 yet encapsuled, — thirteen, twenty, 

 twenty-four years, from the time at 

 which their invasion had taken 

 place. 



Virchow relates a case, where, 

 after the lapse of thirteen and one-half 

 years, the parasites moved in their 

 capsules on prolonged exposure to 

 the heat of the sun. 



Professor Damman, reports an in- 

 teresting case of the longevity and 

 encapsuling of trichinae in the mus- 

 cles of a pig. This hog was fed by 

 Von Behr, in Schmaldow, with trich- 

 inous pork in November, 1864. Since 

 that time the animal had been kept 

 isolated in a pen of its own, unless 

 taken out for examination. On the 

 3d of February, 1875, and 20th of 

 February, 1876, he removed a small 

 piece of flesh from the muscles near 

 the shoulder. In both cases the mi- 

 croscopic examination demonstrated 

 the presence of trichinae. Rupture 

 of the capsule and the application of 

 moderate heat demonstrated that they 

 still lived. In this case we have un- 

 questionable proof of the presence 

 and continuance of living trichinae 

 capable of development for a period 

 of eleven and one-quarter years from 



the time of the infection of the 

 swine.* 



Although the capsulated trichinae 

 suffer no changes while confined in 

 the muscles of a living organism, yet 

 the introduction of portions of such 

 muscles into the intestinal tract of 

 man, or other suitable animal, causes 

 rapid changes in their condition. 

 The processes of digestion soon set 

 the embryonal parasite free from its 

 capsule, three to four hours being 

 sufficient for the purpose ; the freed 

 parasites rapidly complete their de- 



FiG. 11. — Pathologically changed Trichinae- 

 capsules. Trichinae dead. (Leuckart.) 



velopment, becoming matured trich- 

 inae. Thirty to forty hours are in 

 general sufficient to complete this I 

 metamorphosis. In cases of fresh 

 invasion, when the capsules have not 

 become hardened to any great de- 

 gree, twenty-four hours have been 

 found sufficient to demonstrate the 

 presence of sexually matured trichinae 

 in the intestines of animals fed with 



*Zeitschiift fur Theirheilkunde, Vol. Ill, 

 p. 93. 



