INDIAN NATIONAL LIFE 85 
the first instance contained nothing living, and to shield from 
the liquids which are placed in the vessels that are used 
the access of all germs from outside—under those con- 
ditions neither fermentation, nor putrefaction, nor any change 
of that kind ever took place. Then Pasteur thought that 
disease, like putrefaction and fermentation, was probably the 
work of organisms which had access to the human body. 
And he began to realize his desire to investigate disease. 
The first disease that he took up was one that afflicted sheep, 
known as anthrax or charbon, and also as wool-sorter’s disease 
because it is one which can be communicated to humanity. 
He very soon found that a new organism was evident in 
the blood of infected animals which was not in healthy blood, 
and by taking blood from these infected animals and inoculat- 
ing healthy animals with it he was very soon able to prove 
beyond all doubt that the transmission of the disease from 
one animal to another depended upon the communication 
of the germ. 
The next disease was one affecting fowls, and he found 
the same thing: that in chicken cholera the disease was ac- 
companied always by the presence in the blood of a germ, 
which was the means of transmitting the disease to another 
animal. Then he found out, by what many people would 
call mere accident—the accident that only men of genius can 
use—something very much more important, viz. that if you 
kept the active germ it lost virulence and after a certain 
number of days, if introduced into healthy animals, would 
produce the disease in a mild form. And he found that when 
an organism of that kind, one whose potency had been 
weakened, was injected into the healthy animal not only 
did the animal have a mild attack, but it became immune 
to the influence of the active organism. He discovered, in 
fact, the principle of treatment now so well known and so 
widely practised, that of preventive inoculation or vaccination, 
