290 PASTEUR: THE HISTORY OF A MIND 



therefore, necessary to prevent spores from forming, 

 at the same time keeping the bacillus alive. This can 

 be accompHshed in different ways, the first successful 

 method being the use of antiseptics. That did not 

 satisfy Pasteur. He wished a second edition of the 

 chicken cholera. He searched in another direction 

 and finally discovered that it sufficed to keep the culture 

 in a shallow layer of neutral chicken bouillon at 42-43'^ C. 



We then see reproduced the same phenomena as in 

 chicken cholera. After a month passed under these 

 conditions, a little extreme as to temperature, the bac- 

 teridium is dead, that is to say, the best culture medium 

 inoculated with it remains steiile. After 8 days, cultures 

 are still made from it readily and give abundant growth, 

 but the organism is harmless to the guinea-pig, the 

 rabbit, and the sheep, three species most susceptible 

 to anthrax. Before the virulence is lost, it passes in 

 the course of about a week through all degrees of atten- 

 uation, and, as in the case of the chicken cholera organ- 

 ism, each of these grades of attenuated virulence may be 

 indefinitely preserved through cultures. Thus vaccines 

 were created. Nothing is easier than to find in these 

 graded viruses the means of giving to sheep, cows, and 

 horses a benign fever, capable of preserving them after- 

 wards from the fatal disease. 



These vaccines had in this respect a practical impor- 

 tance very much greater than those of chicken cholera. 

 The victims of anthrax were counted by thousands in 

 France alone, and the losses were reckoned in millions. 

 Anthrax vaccination could remedy all this but before 

 bringing about its acceptance, what trouble, what time, 

 what efforts to convince the pubhc, the veterinarians 

 and the farmers! Here it is that we shall find again 

 Pasteur the apostle, whom we have seen in action 

 after his studies on the silkworm, the Pasteur who 



