DISEASES OF SWINE AND OTHER ANIMALS. 875 
by microscopic worms in the walls of the bowels, were, in all probability; 
the victims of an epizootic of Sclerostomata. 
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 Sclerostomata, though both were diligently sought for. 
Cysticercus Zemicollis—This hydatid I found in considerable numbers 
in the abdominal cavity (in the omentum, peritoneum, liver, kidneys, 
&c.), in the pelvis, perineum, and pleure of my first lot of pigs. It con- 
sists of an ovoid bag of liquid 4 to 1 inch in length, with an opening at 
one end, through which the head is drawn back into the sack. The head 
is supported on a very attenuated thread-like neck, whence the name. 
The membrane of the sack is marked by fine transverse stri«, and if 
placed in tepid water will 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 puppy, fresh 
from its mother, ten having been kept for some time in a solution of 
common salt, while seven were fresh from a newly-killed pig. After 
twenty-five days the puppy was sacrificed, and seven tapeworms (Tenia 
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 hooklets, having 
the characteristic long posterior process as shown in the accompanying 
lithograph (Plate XIV, Figs. 9 and 10); also the calcareous markings in 
the head and neck already referred to. 
It is well known that when several ripe segments of this tapeworm are 
ven to a sheep or: goat, the myriads of resulting embryo worms that 
ore 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 evidence in the entire absence of these para- 
sites in my later lot of pigs, showing that they were in no way responsi- 
ble for the specific hog-fever. 
Other parasitic worms of swine.—It is needless to open up the question 
of the causation of this disease by the other worms of swine. Many 
years ago Dr. Fletcher called attention to the destructige effects of the 
lard worm—Stephanurus Dentatus—(misnamed Sclerostoma Pinguicula) 
on the liver and other internal organs, and even attributed the hog- 
cholera to its ravages. Doubtless he was dealing with an epizootic of 
this worm, but in many instances since, as in my own recent cases, this 
worm has been sought for in vain. 
So with the Zrichina Spiralis, the Hook-headed Worm (Echinorhynchus 
Gigas), the common measle hydatid (Cysticercus Cellulosa), and the liver 
flukes (Fasciola Hepatica, and Distomum Lanciolatum); however de- 
structive they may be to pigs in infested localities, their entire absence 
in my experimental pigs sufficiently excludes them from the causation 
of the specific hog-fever. 
EXPERIMENTS ON THE PROPAGATION OF THE DISEASE BY INOCULA- 
TION AND OTHERWISE. i 
Virulence of dried virus.—In experimenting on the hogs it was sought, 
first, to ascertain the tenacity of life of the dried virus. This was indi 
