from an Agricultural and Veterinary Point of View. 103 
■condition of long duration in the vitality of the germs is not 
«ven indispensable ; for, if I may believe the doctors Avho have 
visited these countries, in all places liable to the plague, and in 
the intervals of the great outbreaks of the epidemic, cases may 
be met with of people attacked with boils, not fatal, but re- 
sembling those of the deadly plague. Is it not probable that 
these boils contain an attenuated virus of this disease, and that 
the passage of this virus into exhausted bodies, which abound 
■only too freely in periods of famine, may restore to it a greater 
virulence? The same may be the case with other maladies 
which appear suddenly, like typhus in armies and in camps. 
Without doubt, the germs which are the cause of these diseases 
•are everywhere scattered around, but attenuated ; and in this 
state a man may carry them about with him, or in his in- 
testines, without suffering much, if any inconvenience. They 
only become dangerous when, through overcrowding, and 
perhaps successive developments of them on the surfaces of 
wounds, in bodies enfeebled by disease, their virulence becomes 
exaggerated." 
The manner in which animals became infected with anthrax; 
also engaged Pasteur's attention, now that it had been definitely 
•established that it was due solely to a microbe or its spores. 
This organism is now well known to all pathologists as a rod- 
shaped body, multiplying, when allowed oxygen or air, by 
dividing across, and measuring from jt^jq^ to the vj^'q-q of an 
inch in length, and about ys^o inch in breadth, it has an 
outer case or sheath, and inside this is fine granular protoplasm, 
the vital part of the organism. In this the spores appear as 
glistening points, which gradually become ovoid, and increase 
in size by the protoplasm collecting closely around them, until 
they fill the rod or sheath, like peas in their pod ; the sheath now 
either breaks off in segments, which burst, and the spores are 
set free ; or it becomes softened and dissolves, leaving them at 
liberty in the middle of the pulp. These, as has been already 
mentioned, are extremely tenacious of vitality, and develop 
into the rod-like bodies or bacilli, when cultivated artificially, 
or introduced into the blood of animals. 
When sheep, cattle, or horses at large become affected with 
anthrax, this must be due to their receiving the spores from some 
external source ; and that this may be the pasturage, was proved 
by an experiment, in which several groups of sheep were fed 
on grass which had been sprinkled with artificially-grown bacilli 
or their spores. Some died from anthrax, and many survived 
after having been visibly affected — the period of latency being in 
some cases eight or ten days, in others much less. If prickly or 
stubbly plants, however, were added to the infected herbage, the 
