182 
D. E. SALMON. 
s,ii} to admit a second disease and calls it septicemie gangreneuse 
Dr. Paul Cagny, who was sent by Pasteur to carry out the vac¬ 
cinations in Baden, says in a recent letter to Dr. Cornil: “It 
is necessary in the first place to indicate that two different bacter¬ 
ial (microbiennes) diseases have been confounded—one is certainly 
the rouget caused [by the short and fine microbe described by 
Pasteur and Thuillier and for which the preventive vaccination 
should be employed ; the other is caused by a large and long 
microbe discovered by Klein, of London.” In Germany there is 
the rotfilauf\ now admitted to be identical with rouget , but it is 
still an open question if the schweineseuche is the same disease. 
Consequently, if there are two or more different diseases in 
Eui ope they cannot all be identical with our hog cholera j and if 
it should happen that we have confounded two or more diseases 
in this country, then Pasteur’s vaccine could only prevent a part 
of our losses, admitting that we have a disease identical with 
rouget. 
As so little is settled about the swine diseases of Europe we 
find it necessary in any comparisons of value to take the cliarac- 
tois of i ouget, as the malady is produced by the Pasteur virus, or 
by contagion from a disease recognized by competent authority 
to be the same. We may compare the characters of that disease 
with our hog cholera under the following heads : 
1st. Incubation. Ihe period of incubation—that is the period 
which elapses between exposure to a contagion and the appear¬ 
ance of the first symptoms of the malady—is certainly one of the 
most important characteristics of a contagious disease. With our 
hog cholera tills period varies from five to eighteen days in sum- 
mei and fiomten to twenty-one days in winter ; the average is 
seven or eight days in summer and two weeks in winter. This 
refers to cases of disease produced by exposure to infected pons 
01 to sick hogs. The symptoms appear somewhat sooner when 
animals aie inoculated, but the period is even then very rarely as 
short as four days, and is generally twice this length. Now 
taking the experiments of Cagny in France {Bui. Soc. Cent, de 
j\fed. Vet ., l88o, p. 151) and Lydtin in Germany {Die Itotlilauf 
der Schiveine) we find that when pigs are exposed to the contag- 
