DR. WILLEMS. 
355 
X. The fresh liquid product of the exudation of the lungs 
of a sick animal, in the first or second degree, is the best to inoc¬ 
ulate with. 
XI. The tail of the animal is the best part to implant the virus. 
XII. Inoculation produces effects more violent upon the sub¬ 
ject, or in the herds exposed to epizootic than upon others not 
contaminated. 
XIII. Inoculation does not act as derivatives do, such as 
seton, trochiscus, &c.; it is not either, a septic inoculation. 
XIY. The virus of pleuro-pneumonia possesses the proper¬ 
ties of virus in general, that is, those of contagion, incubation and 
regeneration. 
XV. In the exudate of the lungs, in the collections of the 
pleura, and again in other parts of the diseased animal, as also in 
the products of the inoculation are found germs corpuscles—mi¬ 
crobes which are the agent of the transmission of pleuro-pneu¬ 
monia. 
XVI. Exudative pleuro-pneumonia, better known to-day, 
must not any longer be classified in the class of virulent, but in 
that of parasitic diseases. 
I. 
CONTAGION AND SPONTANEITY. 
At the time of my first researches upon exudative pleuro-pneu¬ 
monia, in 18d9 and 1850, those, who until then, had studied this 
disease, were far from agreeing as to its nature and its contagious 
character. Some considered it as a purely inflammatory disease 
of the pulmonary tissues, brought on by external causes, such as 
cold, giving rise to a pneumonia a frigore , such as a too alibile, 
exciting food, &c. Others, more perspicacious, saw in it a general 
disease,—an affection of a specific and contagious nature, and this 
opinion prevailed principally in Germany. These two opinions 
upon the nature and character of exudative pneumonia, gave rise 
to two parties of observers, the contagionists and the spontaneists. 
To-day, opinions have changed, and almost all those who have 
studied this serious problem admit the contagion ; only a few, and 
