46 



THE AMERICAN MONTHLY 



LMarch, 



As the migration of the embryonal 

 trichinae gradually ceases, so do these 

 abdominal phenomena relax in their 

 severity, and finally disappear, unless 

 a second invasion takes place. The 

 invasion of the several muscular sys- 

 tems is indicated by pain, swelling, 

 and disturbance of the motor func- 

 tions. If these do not lead to death 

 by exhaustion, they in their turn 

 gradually cease with the encapsuling 

 of the trichinse. 



Fig. 14. — Psorosperms in muscle of swine. 

 (Leuckart.) 



The experiments of Prof. Leiser- 

 ing, of the Royal Veterinary Institute 

 at Dresden, entirely agree with the 

 above. He says {Bericht iiber das 

 Veterindr- We sen im Konigreich Sach- 

 sen, 1862, p. 188), " One cannot 

 speak of a trichina-disease in swine, 

 which is characterized by distinct and 

 pathognomonic phenomena. In this 

 relation, the trichinae deport them- 

 selves in a manner similar to the 

 cysticerci (measles). Leisering made 

 some feeding-experiments with tri- 

 chinous flesh by a horse, but the most 

 exact examinations failed in discover- 

 ing a single parasite in his flesh. It 

 may also be casually remarked that 

 fowls present some unknown hinder- 

 ance to an invasion of their flesh by 

 embryonal trichinae. I made quite 

 a number of experiments with hens, 

 feeding them for two weeks almost 



entirely upon pork profusely infected, 

 but was unable to find a single tri- 

 china in their flesh. 



How do swine become infected 

 under the natural order of things ? 

 or, in other words, whence do they 

 derive the trichinae ? That the para- 

 sites gain access to an organism by 

 means of the mouth and alimentary 

 canal, is placed beyond all doubt. 

 Notwithstanding the apparent nega- 

 tion of the above-quoted Berlin experi- 

 ments, other authorities affirm, from 

 positive observation, that the intestinal 

 and embryonal trichinae do leave the 

 invaded animal with the faeces, as is 

 attested to by such observers as 

 Leuckart, Vogel, Kuhn, Gerlach, and 

 others. It is this form of migration, 

 which under favorable circumstances 

 also contributes to the distribution of 

 the trichinae. In fact, Haubner and 

 Gerlach mention cases where they in- 

 tentionally caused infection of young 

 non-infected swine, by placing them 

 with those known to be infected. 

 Such embryos and pregnant females 

 become mixed with the manure and 

 bedding of the hog-pen, and may be 

 taken up by any swine, even by those 

 first invaded, thereby leading to a 

 second infection, self-induced. Of 

 all animals in which these parasites 

 have been found, none have that in- 

 terest to the hygienist and experi- 

 mental pathologist which is enjoyed 

 by the rat, on account of a hypotheti- 

 cal aetiological connection between 

 the trichinae which have been found 

 to infest them in large numbers, and 

 those of swine. Leisering is the ori- 

 ginator of this hypothesis. 



Forty rats caught at one of the 

 large pork-packing houses near Bos- 

 ton were all found trichinous. Of 

 60 rats caught for me at different 

 stables in the city of Boston, where 

 no hogs were or had been kept, but 

 six were found trichinous. 



The results of these examinations 



are sufficient to strengthen my scep- 



i ticism with regard to the rat-infection 



theory, and seem to indicate that the 



rats get the disease from eating pork, 



