TRICniXIASIS OF MAN AND ANIMALS. 3 



this disease is of comparatively modern date, still we have no justi- 

 fiable reason for doubting the presence of these parasites in swine 

 at a very early date, and also that the consecutive disease in man 

 must have existed for years, if not centuries, before it came to sci- 

 entific recognition; I am inclined to think, almost coeval with the 

 consumption of pork as food. In this opinion I find myself op- 

 posed by many distinguished observers ; but the fact that trichinae 

 were not discovered earlier than 1831 does not at all militate against 

 my conclusions. They simply were not suspected. Every fact in 

 connection with the history of the parasite — its minuteness, the un- 

 certainty of its pathognomonic phenomena in man, and still more 

 so in the hog, which render ditticult the correct diagnosis of trichi- 

 niasis — supports my hypothesis. 



Ililler* says: "The history of this disease can be appropriately 

 divided into three periods, the first beginning with the discovery, 

 or observation, of the capsule — the parasite not being recognized — 

 in 1S21-'2S, including the description of the same by Dr. Hilton, 

 of Guy's Hospital, London, England, in 1S35. 



'• The second period extends from 1835, when Paget discovered 

 the encapsulated parasite and Owen described it, giving to it its 

 name, 'trichina spiralis,' to the first authentic observation of the 

 disease in a human being, and the direct establishment of its con- 

 nection with a parasitic disease of swine which took place in 1860. 



" This begins the third period in the history of trichina spiralis — 

 the period of active scientific investigation — which is by no means 

 at an end, and which awaits its conclusion in the discovery of the 

 original source whence swine derive the parasite." 



In the mean time, Professor Leidy, of Philadelphia, was the first 

 to discover the parasite in the flesh of the hog in 1867. It is a 

 singular fact that this discovery should have been made by means 

 of an American hog. 



The principal workers in this important field of helminthic re- 

 search have been Owen, Cobbold, Bristow, and others, in Britain ; 

 and Leuckart, Virchow, Zenker, Kiichenmeister, and the veterinari- 

 ans Gerlach and Fiirstenberg, in Germany. 



Cobbold t describes the parasite as follows : " Trichina sjnralis is 

 an extremely minute nematode lielminth, the male in its fully de- 

 veloped and sexually matured condition measuring only one eigh- 

 teenth of an inch, while the perfectly developed female reaches a 

 length of about one eighth ; body rounded and filiform, usually 

 slightly bent on itself, rather thicker behind than in front, espe- 



* Ziem?3cn's " Encyclopscdia of Medicine," vol. iii. f " Entozoa," p. 335. 



