EDITORIAL. 
799 
from this experiment as tuberculous infection never occurs in 
this way. 
(5) This last conclusion is one which has the highest im¬ 
portance to the practical point of view, viz.: that upon none of 
the animals experimented upon, no matter how short the incu¬ 
bative stage had been, or how quick the evolution of the 
disease had been, none of the lesions had undergone the process 
of softening or of calcification, which it may be said is the rule 
among tuberculous bovines. 
To resume and answer the two principal questions presented 
to the commission : 
(1) Whatever is the mode of contamination, a certain lapse 
of time always passes between the time when the contagion 
has entered the organism and that when it manifests its effects 
by reaction to tuberculin; the duration of this incubation 
varies ; in the experiments, where the chances of infection were 
the greatest, it has been of 19 to 32 days for infection by in¬ 
halation and of 32 to 48 by ingestion. 
It is certain that in ordinary natural contagion, the dura¬ 
tion of the incubation is longer. 
If, then, a recently bought cow reacts to tuberculin within 
30 days from the day of sale, the practitioner is perfectly au¬ 
thorized to conclude that, in all probability , the animal was in¬ 
fected before the sale. 
(2) It is often difficult to give an opinion as to the age of 
the lesions found at the autopsies : the experiments do not bring 
definite answers to that subject; yet, if the lesions that are 
found at post-mortems are softened or calcified, whatever may 
be their extent, no matter how small and limited, the veteri¬ 
narian can now in all certainty say that these lesions have 
existed for more than fifty days. 
* * * 
Universal Exhibition of 1900. —The great international 
fair of Paris has closed, and of all the grandeur which filled it 
and was witnessed by millions of people, there soon will re¬ 
main but the souvenir. Millions of people came—and among 
