A NEW PASTEURELLOSE. 
333 
In seven of those calves, I found again the same pasteurella. 
In three cases, with very acute evolution, this microbe 
existed almost all alone in the blood of the heart, in that of the 
spleen ; the liver, the lymphatic glands and the umbilical clot 
contained besides many other microbes ; in a fourth case, it was 
this exudate of a very recent arthritis alone and without any 
other microbe; in the three other cases, where the disease has 
proceeded slowly, I had to multiply the cultures and the inocu¬ 
lations to isolate it from the crowd of other microbes which had 
invaded the blood and the tissues. 
The presence of a virulent pasteurella in the tissues of calves 
affected with white scour was not then an exceptional fact, 
limited to articular complications ; it may be said that it is the 
rule. 
Does it follow necessarily that this pasteurella is the cause 
of white scour ? A doubt is allowed by its absence in a small 
number of cases and the presence of other microbes in most of 
the cases. It was, however, probable that this bacteria is cer¬ 
tainly the causal agent of the disease ; because it exists alone 
in cases whose march is very rapid, and, again, because it is 
known, by the minute previous study of other bacteria of the 
same group, specially since the works of my student, Ifigniere, 
that pasteurellas have that power to reduce to nothing the 
natural defenses of organisms, to promote its rapid invasion 
by ordinary microbes which are so numerous in the intestines 
or in the bronchii and which are ordinarily harmless, and finally 
to disappear quickly when the sick are sometimes resistant to 
those multiple infections. 
However, to remove all doubt, it was necessary to produce 
white scour in a healthy calf, with the inoculation of a pure 
culture of this pasteurella. 
This I succeeded in doing in the following experiment : 
April 16, we received at the laboratory two calves : one born 
the day before, on a farm exempt from white scour. The other, 
four weeks old, from a farm where the disease existed ; he has 
been sick, but is considered as recovered, although delicate 
