EELATION OF PATHOGENIC TO SEPTIC BACTERIA. 31 



to a temperature of 42° — 43° C, which is still suitable for the 

 growth of the bacilli, but not for the spore formation; in many 

 instances this is unnecessary, because even at ordinary tem- 

 peratures no spores are formed. Cohn and Koch maintain 

 that for the formation of spores in the bacillus of anthrax as in 

 other bacilli, a certain degree of warmth, a certain degree of 

 moisture, and a sufficient supply of air are indispensable for 

 the formation of spores. There can be no doubt that this is 

 so; Bacillus anthracis does not form spores in the body of 

 an animal, as I can fully confirm Koch against Pasteur, who 

 makes this assumption, and as I have repeatedly convinced 

 myself by direct and systematic observations, to be mentioned 

 in my next Report ; but I cannot admit, if if is said that given 

 those three conditions, viz. a certain degree of warmth and 

 moisture, and a sufficient supply of air, supposing other things 

 unchanged, the Bacillus anthracis must of necessity form 

 spores. This is by no means the case, for I have seen nume- 

 rous cultivations in which these conditions were present, but 

 no spore formation ever occurred, although the bacillus went 

 on increasing in numbers in a most satisfactory way. In the 

 cultivations of Bacillus anthracis in neutral pork broth in 

 test-tubes or flasks, if they are kept quiet, no formation of 

 spores ever occurs. In these instances the absence of a suffi- 

 cient amount of air is no doubt the cause, as I shall show 

 below, the growth taking place at the bottom of a fluid which 

 had been well boiled for the sake of sterilisation. Dr. Loffler 

 (" aus dem Kaiserl. Gesundheitsamte," 1881, p. 134) also 

 suspects that in Pasteur's cultivations it is perhaps not the 

 temperature of 42° or 43° C. which prevents the spore forma- 

 tion, but the immersion of the bacilli in the fluid, for the 

 bacilli form spores at this temperature when cultivated in flat 

 dishes (see below). 



Apart from spore formation, inoculation with Bacillus 

 anthracis of gelatine pork in test-tubes or flasks (and kept 

 solid) yielded slightly different results, according as the inocu- 

 lation was established on the surface of the gelatine or in the 

 depth. In the first case the growth proceeds with rapidity. 



