XIL] Anthrax. 131 



Toussaint and Chauveau obtained the same results at a higher 

 temperature. A culture of this kind ends in the death of the 

 Bacillus, which ensues, according to Pasteur's account, in about 

 a month or a little more than a month. Till this time the 

 Bacillus vegetates without change in its morphological charac- 

 ters, except that the formation of spores is delayed or altogether 

 stopped. That it never takes place is denied by Koch, Gaffky, 

 and Loffler on the ground of direct observation. If the Bacillus 

 is transferred to a fresh culture at any time before death has 

 supervened, it will develope in the normal manner, and even 

 produce normal spores at the proper temperature. If the tem- 

 perature continues to be raised, complete attenuation results in a 

 shorter time ; a few days are required at a temperature of 45 C., 

 a few hours at one of 47 C., a few minutes at one of 50-53 C. 

 The three Berlin observers found that there was a considerable 

 difference between 42 and 43 C. in the time required for total 

 attenuation in correspondence with the temperature-differences 

 of tenths of a degree, the process being accelerated as the 

 temperature rose. 



It follows that if the Bacillus is cultivated at a temperature 

 between 42 and 43 C., we obtain material which will be harm- 

 less to animals in the order of their susceptibility to infection, 

 for instance to rabbits first, after them to guinea-pigs, and lastly 

 to mice ; fluctuations will naturally occur according to indi- 

 vidual susceptibility, age, and other circumstances. 



It has been already stated that the Bacilli are capable of 

 further vegetation after passing through every degree of atten- 

 uation of their virulence before reaching the stage of actual 

 loss of vitality. If their cultivation is continued under optimum 

 conditions they grow in their normal shape and form normal 

 spores, but the successive generations, even when produced 

 from spores, nevertheless retain as a rule the degree of attenua- 

 tion of the first generation; some kill mice for example and 

 are harmless in the case of guinea-pigs, others do not affect the 

 health of mice. Cultures of the latter quality were continued 



K 2 



