FERMENTATION. 269 



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 putre- 

 fying 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. Un- 

 counted millions of these spores are developed in the 

 bod_f 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 towards the extirpation of 

 these contagia is the knowledge of their nature ; and 

 the knowledge brought to us by Dr. Koch will render 

 as certain the stamping out of splenic fever as the 

 stoppage of the plague of pebrine by the researches ol 

 Pasteur.2 q^q small item of statistics will show what 



' Koch found that to produce its characteristic effects the con- 

 tagium of splenic fever must enter the blood ; the virulently in- 

 fective spleen of a diseased animal may be eaten with impunity 

 by mice. On the other hand, the disease refuses to be communi- 

 cated by inoculation to dogs, partridges, or sparrows. In their blood 

 Bacillus anthracis ceases to act as a ferment. Pasteur announced 

 more than six years ago the propagation of the vibrios of the silk- 

 worm disease caWed Jlacherie, 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 de? 

 Vers k Soie,* pp. 168 and 256. 



2 Surmising that the immunity enjoyed by birds might arise 

 from the heat of their blood, which destroyed the bacillus, Pasteur 



