FERMENTATION. 283 



sought to determine how the contagium maintained its 

 vitality. Drying the infectious 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 maintained 

 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 condi- 

 tions. 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 dead- 

 ly 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 anfliracis* 



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 

 * Koch found that to produce its characteristic effects the 

 contagium of 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 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 silkworm disease called flacherie, both by fission and by 

 spores. He also made some remarkable experiments on the per- 

 manence of the contagium in the form of spores. See ' fitudes 

 sur la Maladie des Vers a Soie,' pp. 168 and 256. 



