TRICHINIASIS OF MAN AND ANIMALS. 13 



The female intestinal or matured parasite lives from five to six 

 weeks, and produces at least fifteen hundred embryos. (Leuckart.) 



The newly born embryos are at first buried in the mucus which 

 lines the intestinal canal ; a microscopic examination of such mucus, 

 at this time, will reveal them as free and movable parasites. The 

 embryos soon begin their migration and dispersion over the organ- 

 ism, the first act being the penetration of the intestinal parietes. It 

 seems to be still a matter of discussion as to the means or ways 

 by which further migration takes place. Some authorities, in fact, 

 all the most eminent, favor the view that the parasites proceed by 

 the way of the mesenterium and connective-tissue tracts over the or- 

 ganism, and penetrate the sarcolemma, or sheath of the muscle-fibers. 



Another view, the possibility of which is conceded by the 

 above-named authors to a minor degree, is that the embryos gain 

 access to the circulation, and are transported over the organism by 

 the moving fluid, boring the smaller vessels at convenience, and 

 thus gaining access to the muscles. (Thudicum.) 



Were this the principal path of dispersion, we ought to be able 

 to discover numerous examples of the parasite in the circulating 

 blood of living animals that have been subjected to feeding experi- 

 ments. This has not been the case, however. 



Thus it is evident that the host, or consumer of trichin-infected 

 flesh, provides the means for its own invasion. 



"While this is, in general, the manner in which invasion takes 

 place, it by no means excludes the possibility of the infection of an 

 animal taking place by intestinal trichinae (embryos), which have 

 passed from an already infected organism with its faeces. In this 

 way an infected swine may infect others, or, in fact, give occasion 

 to a secondary invasion of itself, by rooting in the manure of its 

 pen. In the same way swine may become infected from infected 

 human beings where, as is too often the case, the out-houses for 

 the family are placed over the pig-pen, or lead into it, or where the 

 contents of the same are thrown into the piggery for the swine to 

 work over. 



Thus we see the cycle of invasion may frequently continue 

 from swine to man, and from man to swine. 



Trichinae may be assumed to be regular cosmopolitans. "Whether 

 Noah took a pair of them with him into the ark will probably con- 

 tinue to be an open question. They have been discovered in Ger- 

 many, England, Scotland, Denmark, Sweden, Eussia, France, Italy, 

 North and South America, Africa, India, Australia, Spain, Egypt, 

 and Syria. 



