CHICKEN CHOLERA. 
137 
aerobic beings, are always ready to appropriate the oxygen to their 
own uses. 
Is this, however, the only possible explanation of the phen¬ 
omena ? Rigorously judged, no. One may understand the facts 
of non-recidivity by supposing that life of the microbe, instead of 
appropriating or destroying certain elements in the body of the 
animal, on the contrary, add others to them, which would be for 
this microbe an obstacle to its further development. The history 
of the life of inferior beings, and of beings in general, authorizes 
such a supposition. Excreta born from vital functions may resist 
a vital function of the same nature. In certain fermentations, 
one may see antagonistic products take birth during and through 
the act of fermentation itself, and put an end to the active life of 
the ferments and to the fermentations a long time before they 
are complete. In the cultures of our microbe, there might be a 
formation of products, whose presence would explain, somewhat, 
the non-recidivity and the vaccinations. 
Our artificial culture of the parasite will again allow us to 
overthrow this supposition. Let us prepare an artificial culture 
of the microbe, and, after evaporating it to coldness in a vacuum, 
bring it back to its former bulk by the bouillons of culture. 
If the extract contains matters poisonous to the life of the mi¬ 
crobe, and if such is the cause of the possible non-culture of the 
filtrated liquid, the new added portion of the medium ought to 
remain sterile. But in fact, it is not so. We cannot believe that 
during the life of the parasite, substances may appear likely to 
resist its further development, an observation which corroborates 
the opinion to which we were brought upon the causes of the 
non-recidivity of certain virulent diseases. 
In relation to the powers of those extracts of artificial cul¬ 
ture of the microbe of the chicken cholera, another question pre¬ 
sents itself. We have just demonstrated that these extracts do 
not contain substances capable of preventing the culture of the 
microbe. But might they not contain some with which it would 
be proper to vaccinate the chickens ? I have prepared a culture 
of the size of 120 cubic centimeters; filtrated and evaporated to 
coldness, always with manipulations so conducted as to preserve 
