ANTHRAX IS ALSO A VIRUS DISEASE 289 



oculation. This fact had remained in the mind of Pasteur 

 as a question, and he had beheved that he could solve it. 

 Afterwards, calling to mind that chickens, fed upon food 

 contaminated by the cholera organism, do not always die 

 and are sometimes found to be vaccinated when they 

 survive, he had asked himself if the sheep in the preceding 

 experiment had not acquired their immunity through a 

 former contagion caused by food. But then, according 

 to this hypothesis, anthrax was a disease which would 

 not recur. 



Later something else occurred to confirm him in this 

 idea. In a series of experiments made with Chamber- 

 land in the Jura,^ in order to test the value of a cure 

 for anthrax, he had had the opportunity of seeing two 

 cows become very sick as the result of a trial inoculation, 

 but, having resisted, endure without any apparent 

 difficulty a virulent inoculation which made very ill 

 or even killed fresh animals not previously prepared. 



All this proved to Pasteur that anthrax was a virus 

 disease, and now the only question was how to find its 

 vaccine. Naturally, he turned first to the method 

 which had been successful with chicken cholera, and 

 tried to let the bacillus become old in its culture me- 

 dium. But immediately a difficulty arose, that is, the 

 anthrax bacillus very quickly transformed itself into 

 spores, and the spore does not grow old; the spore is a 

 "seed," and for a seed, time is almost suspended.' It was, 



^Sur la non recidive de I'affection charbonneuse (en collaboration 

 avec M. Chamberland). Co. rend, de I'Ac. des Sci., t. XCI, 1880, p. 533. 



- It IS not known how long seeds or spores will live under favorable 

 conditions. Dr. W. J. Beal buried 25 varieties of weed-seeds in sandy 

 soil in bottles of earth, mouth down, and found some individuals of 

 11 varieties alive after 25 years, but they germinated very irregularly. 

 The senior writer put spores of the hay-bacillus into concentrated 

 glycerin, exposed to the air in a cotton-plugged test tube, 10 years ago 

 and a very few are still living. Trs. 



