66 DISEASES OF SWINE AND OTHER ANIMALS, 



by microscopic worms in tlie walls of the bowels, were, in all x>robability, 

 the victims of an epizootic of Sderosfomata. 



That the genuine hog-fever is not caused by either of these worms is 

 best illustrated by the fact that in my second lot I found very few whip- 

 worms and no Sclerosfomata, though both were dihgently sought for. 



Cystlccrcus ZcmicoUis. — This liydatid I found iu considerable numbers 

 in the abdominal cavity (in the omentum, peritoneum, liver, Icidueys, 

 &c.), in the pelvis, j^erineum, and pleurae of my first lot of pigs. It con- 

 sists of an ovoid bag of liquid i to 1 inch iu length, with an opening at 

 one end, through which the head" is drawn bade into the sack. The head 

 is supported on a very attenuated thread-lilie neck, whence the name. 

 The membrane of the sack is marked by fine transverse stria^, and if 

 placetl in tepid water -s^ill often undergo active contractions, during 

 which the head can be seen to rise and fall in the interior. The head 

 and neck contain an abundance of dark calcareous particles, soluble 

 with effervescence in a strong acid. 



Seventeen of these hydatids were fed to a Newfoundland pujipy, fresh 

 from its mother, ten having been kept for some time in a solution of 

 common salt, while seven were fresh from a newly-kiUed pig. After 

 twentj^-five days the pui)i)y was sacrificed, and seven tapeworms {Tcenia 

 Marginata) were found attached by their hooked snouts to the mucous 

 membrane of the jejunum. Exposure to a strong solution of common 

 salt for less than a week in some cases had been sufficient to destroy the 

 first ten, while all the seven cysticerci, grown fresh, developed into tape- 

 worms. These had the globular head with four sucking disks and re- 

 tractile proboscis, surrounded by a double row of 36 booklets, having 

 the characteristic long .posterior process as shown in the accompanying 

 lithograph (Plate XIT, Figs. 9 and 10); also the calcareous markings iu 

 the head and neck akeady referred to. 



It is well known that when several ripe segments of this tapeworm are 

 given to a sheep or goat, the myriads of resulting embryo worms that 

 bore their way into the liver and other organs will give rise to such de- 

 structive changes in them that death may ensue in ten days. But here 

 again we have the counter e\'idence in the entire absence of these i)ara- 

 sites in my later lot of pigs, showing that they were in no way responsi- 

 ble for the sj)ecific hog-fever. 



Other parasitic worms of swine. — It is needless to open up the question 

 of the causation of this disease by the other \^ orms of swine. Many 

 years ago Dr. Fletcher called attention to the destructive effects of the 

 lard worm — Stcphanurns Dentatus — (misnamed Sclerostoma Pingnicula) 

 on the liver and other internal organs, and even attrilSuted the hog- 

 cholera to its ravages. Doubtless he was deahng with an epizootic of 

 this worm, but in many instances since, as iu my own recent cases, this 

 worm has been sought for in vain. 



So with the Trichina Spiralis^ the Hool'-headcd Worm {Ec]tinorhynrhi(S 

 Gifjas), the common measle hydatid {Cysticercus CeUnlosa), and the liver 

 flukes {Fasciola Mcpatica, and Distomum Lanciolatum)] however de- 

 structi\'e they may be to pigs in infested localities, then- entii'e absence 

 in my experimental pigs sufficiently excludes them from the causation 

 of the specific hog-lever. 



EXrERIMENT« ON THE PllOPAGATION OF THE DISEASE BY INOCULA- 

 TION AND OTHiyRWISE. 



Virulence of dried virus. — In experimenting on the hogs it Avas sought, 

 first, to ascertain the tenacity of life of the dried virus. This was iudi- 



