PATHOLOGICAL PHYSIOLOGY. 
471 
true agents of virulency, so long as tlieir inoculation in susceptible 
organisms gives rise to the manifestation of the disease from 
which they proceed, with just as much certainty as the inoculation 
of the natural virulent matter. 
Nothing can be more demonstrative than these experiments. 
They prove, in a general way, the existence of virulent semence , 
constituted by isoluble corpuscles, which are the necessary agencies 
of contagion. 
These admirable discoveries^constitute an important epoch in 
the general history of virulency, since from them have proceeded 
the first positive conceptions of the nature of the contagious ele¬ 
ments in diseases not acknowledged as parasitical. Before their 
development, the reign of uncertainty and obscurity was complete. 
In their presence, light began to be thrown upon the phenomena 
of contagion, which had hitherto stood upon a mere basis of 
hypothesis. Mr. Chauveau would, no doubt, have made still 
further progress had not his mind been preoccupied and dominated 
by the idea that between contagious diseases, properly so called, 
and those in which the virulent element was constituted by a 
parasite, the distinction was absolute, and that they belonged 
each to a category essentially foreign to the other. 
It is this idea which deterred him from experimenting with 
the cultivation of these corpuscles, and demonstrating with his 
admirable sagacity the inherency of virulent activity, to the ex¬ 
clusion of the solid or liquid organic matters with which these 
corpuscles might be associated. 
This division, which seemed to be well established when Mr. 
Chauveau made his experiments, has since, and by Mr. Chauveau 
himself, been recognized as an erroneous expression of the real 
nature of the facts. 
As our knowledge progresses and our researches are multi¬ 
plied, new facts appear to convince us that the phenomena of 
contagion are determined by one converging law in both living 
kingdoms, and whatever may be the species of disease, whether 
of animal or vegetable organisms, the rule is invariable that 
wherever there is contagion it proceeds from a living agent, which 
is the necessary factor in the case. 
When the living element of a contagion of a large size pre- 
