FERMKN'IATION. 557 
blood containing the rod-like organisms, in which, however, 
the spores were not developed, he found the contagium to 
be that which Dr. Sanderson calls " fugitive/' It main- 
tained its power of infection for five weeks at the furthest. 
He then dried blood containing the fully-developed spores, 
and exposed the substance to a variety of conditions. He 
permitted the dried blood to assume the form of dust; 
wetted this dust, allowed it to dry again, permitted it to 
remain for an indefinite time in the midst of putrefying 
matter, and subjected it to various other tests. After keeping 
the spore-charged blood which had been treated in this 
fashion for four years, he inoculated a number of mice 
with it, and found its action as fatal as that of blood 
fresh from the veins of an animal suffering from splenic 
fever. There was no single escape from death after 
inoculation by this deadly contagium. Uncounted millions 
of these spores are developed in the body of every animal 
which has died of splenic fever, and every spore of these 
millions is competent to produce the disease. The name 
of this formidable parasite is Bacillus anthracis.* 
Now the very first step toward the extirpation of these 
contagia is the knowledge of their nature; and the knowl- 
edge brought to us by Dr. Koch will render as certain the 
stamping out of splenic fever as the stoppage of the plague 
of pebr.ine by the researches of Pasteur, f One small item 
of statistics will show what this implies. In the single 
district of Novgorod in Russia, between the years 1867 and 
1870, over fifty-six thousand cases of death by splenic 
* Koch found that to produce its characteristic effects the contagium 
of the splenic fever must enter the blood; the virulently infective 
spleen of a diseased animal may be eaten with impunity by mice. 
On the other hand, the disease refuses to be communicated by inocu 
lation to dogs, partridges, or sparrows. In their blood Bacillus 
ti/it/intcis ceases to act as a ferment. Pasteur announced more than 
six years ago the propagation of the vibrios of the silk-worm disease 
called flacherie, both by fission and by spores. He also made some 
remarkable experiments on the permanence of the contagium in the 
form of spores. See " Etudes sur la Maladie des Vers a Soie," pp. 
168 and 256. 
f Surmising that the immunity enjoyed by birds might arise from 
the heat of their blood, which destroyed the bacillus, Pasteur 
lowered their temperature artificially, inoculated them, and killed 
them. He also raised the temperature of guinea-pigs after inoculation, 
and saved them. It is needless to dwell for a moment on the impor- 
tance of this experiment. 
