KOCH : THE SPORE OF ANTHRAX 241 



meadows are not so; why do not the flies pass from one 

 to the other? And furthermore, if they are the agents 

 of transmission all the cases of anthrax in animals ought 

 to begin with a subcutaneous tumor or a lesion of the 

 mucous membrane, similar to the malignant pustule in 

 man, the origin of which is always external. 



But these cases of external anthrax are very rare 

 among the domestic animals. It was necessary, there- 

 fore, to search for some other explanation. But what? 

 No one knew. In the meantime, as long as the bac- 

 teridium did not explain or explained so badly the eti- 

 ology of the disease, the partisans of the theory of spon- 

 taneous anthrax had a good chance, and the opinion 

 of the investigators was still wavering when the work 

 of Koch appeared. This dissipated many of the obscur- 

 ities and silenced some of the objections. 



KOCH: THE SPORE OF ANTHRAX 



It was in reality this work which introduced into the 

 question a very important idea, that of the spore, which 

 plays so great a role in our ideas of to-day, but which 

 at that time, was unknown or at least abandoned. 

 Pasteur had observed, in 1863, the formation of spores 

 in the butyric vibrios. But he had not foreseen their 

 role nor did he know their exact significance. In 1869 

 he had found them in the vibrios of the flacherie of the 

 silkworm and, this time, he had proved that these spores, 

 these cysts, as he called them, had a resistance greater 

 than that of the rods, and could endure a long drying. 

 By means of these cysts he had explained the persist- 

 ence of the epidemics of flacherie in different regions. 



