ANTHRAX IS ALSO A VIRUS DISEASE 287 



active on them than its heat. This might be conceived 

 as due to intermittent cultures which renew and multiply 

 the spores, but there is no probability in such an 

 explanation, the soil, rich in vegetable matter, being 

 full of organisms which are much better prepared 

 than the anthrax bacteridium to profit by the slightest 

 condition favorable to bacterial growth. Pasteur was 

 seeking an explanation in some other direction, but he 

 knew not where. The solution came to him by intuition 

 one day, in the course of a walk. "It was after the 

 harvest; there remained only the stubble. The atten- 

 tion of Pasteur was drawn to a portion of the field be- 

 cause of the difference in the color of the soil. The 

 owner explained that some sheep which had died of 

 anthrax had been buried there the preceding year. 

 Pasteur, who always investigated things very closely, 

 observed on the surface of the soil a multitude of the 

 tiny castings of earthworms. The idea occurred to 

 him then that in their continual journeys from the 

 depths to the surface, the worms brought with them soil 

 rich in the humus which surrounds the carcass of the 

 animal, and with it the anthrax spores which it contains. 

 . . . Pasteur never stopped with theories; he imme- 

 diately proceeded to experimental work. The latter 

 justified his suppositions, the earth from one of the 

 worms when inoculated into guinea-pigs gave them 

 anthrax." 1 



These spores, brought to the surface of the soil in 

 this way, contaminate vegetation and reach by way of 

 food and drink the digestive canal of the farm animals. 

 Sheep which are kept over the spot where a victim of 

 anthrax is buried, easily contract anthrax, especially if 

 their food contains chaff, stubble, awns, or small prickly 



1 L'CEuvre m6dicale de Pasteur, par le Dr. E. Roux, Agenda du chimiste, 

 1896. 



