DISEASES OF SWINE AND OTHER ANIMALS. 349 
Up to date pig C has presented the appearance of a perfectly healthy 
pig. Its ears have healed, and are now (November 11th) perfectly smooth. 
It is lively and greedy for its food, but has grown very little, and weighs 
to-day about half as much as pig A. It can be seen very plainly that 
pig C has been sick. When I received A, B, and C, A was slightly the 
best pig. B came next, and C was the smallest, but the difference was 
only a trifling one. 
The experiments just related show that the bacilli and their germs 
must have a causal connection with the morbid process of swine-plague, 
because an inoculation with bacillt and bacillus-germs, cultivated in such 
an innocent and harmless fluid as milk, produced the disease, while an 
inoculation with blood-serum from diseased lungs—a highly infectious 
fluid, if not deprived of its bacilli-and bacillus-germs—remained without 
the slightest effect after it had been freed from its bacilli and bacillus- 
germs. I know very well that the result obtained can hardly be consid- 
ered as conclusive, and that some more experiments of the same kind are 
needed to confirm the conclusions arrived at. 
5. THE CONTAGION, THE CAUSES, AND THE NATURE OF THE MORBID 
PROCESS. 
That swine-plague is an infectious disease, which can be communi- 
cated to heathy animals, has been demonstrated by my experiments. 
It has further been proven that an exceedingly small quantity of an 
infectious or contagious substance (blood-serum or exudation, for in- 
stance) if inoculated, or directly absorbed by the vascular system, is 
sufficient to produce the disease. It has also been proven that morbid 
tissues and morbid products, if consumed by healthy pigs, will cause 
them to become affected with the plague. Consequently, two ways of 
infection have been ascertained with certainty. Further, if the results 
of the post-mortem examinations are inquired into more closely, it will 
be found that the principal morbid changes have occurred in the digest- 
ive canal, but especially in the cecum and colon, in all those cases in 
which the disease had been communicated by way of the digestive ap- 
paratus; and that, on the other hand, the principal seat of the morbid 
process has been in the organs of respiration and circulation, or in the 
organs situated in the thorax if the contagion had been inoculated or 
been introduced into the system through wounds and absorbed by the 
veins and lymphatics. 
Whether an inhalation of the contagious or infectious principle into 
the respiratory passage or into the lungs is suificient to produce the 
disease is doubtful. One pig (pig No. 1), an animal free from any lesions 
or wounds whatever, has been exposed twice and has not contracted 
the disease; but while exposed and immediately after its pen was moved 
once a day, and as the pen was thus kept clean, and as dry earth isa 
good disinfectant, it must be supposed that the animal was never obliged 
to consume the contagious principle clinging to the excrements of the 
diseased animals, neither with its food nor with its water for drinking. 
Its trough was cleaned three times a day, and always before fresh water 
was poured in. Pig B, however, was exposed only once, by being kept 
together with pig No. 6, and contracted the disease in due time. But 
the conditions were entirely different. Pen No. 3, in which both pigs 
were kept, contains a wooden floor; pig B was put in soon after pig No. 
5 had died, and the pen, otherwise always cleaned once a day, had been 
left dirty (uncleaned) on purpose. So it happened that the ears of corn, 
thrown on the floor for food, became soiled, though perhaps only slightly, 
