Anthrax. 239 



the drying up of the customary drinking places becomes an im- 

 portant factor. Plethora and starvation are alike predisposing, 

 probably by lessening the resisting power of the system. Over- 

 work and exhaustion predispose, as Roger showed by making the 

 immune white rat turn a wheel until worn out and then success- 

 fully inoculating it. The addition of lactic acid to the virulent 

 liquid (1:500) greatly encreases its potency (Arloing, Cornevin 

 and Thomas) and the further addition of fermentescible sugar 

 (and rest) enhances this still more (Kitt). The production of 

 lactic acid by muscular overexertion is thus a potent accessory 

 cause in fatigue. In milk ducts of the susceptible it proves 

 fatal : in those of the immune it lives indefinitely, killing slowly by 

 toxine poisons and marasmus. (Nocard). 



Bacillus anthracis. This was first demonstrated in anthrax blood 

 and exudates by PoUender and Brauel in 1849 and 1850 but as they 

 failed to find it in all cases they concluded that it was not the essen- 

 tial cause. Davaine who found the bacilli in 1850 suspected that 

 they were pathogenic and by 1863 he had shown that blood which 

 contained no bacilli was non- virulent, while that in which these 

 organisms were present was constantly infecting. Klebs and 

 Tiegel in 1871 filtered anthrax blood through an earthenware 

 vase and found that the clear filtrate (bacillus-free) was non- 

 infecting. 



The bacillus anthracis as found in the blood is a nonmotile rod- 

 shaped organism, 5 to 20/u long by i to 1.5/t broad with ends 

 apparently square, but really slightly cup shaped as seen in the 

 stained specimens when two have remained connected end to end. 

 Under favorable conditions a clear hyaline envelope may be seen 

 around the bacillus. Though usually isolated in the living blood, 

 yet in bouillon cultures the bacilli grow out into long flexible fila- 

 ments, made up of separate segments which are easily distin- 

 guished in the stained specimen. In all cultures out of the 

 living animal body, in the presence of air and at a suitable tem- 

 perature spores form endogenously in the bacilli, exceptionally 

 polar, and are set free by the granular degeneration of the latter. 

 In peptonized bouillon this may occur in four days at i4°C., or 

 in eight hours at 37° to 4o°C., but not above 42°C. (Schreiber. 

 Centr. S. Bact. 1896). Sporulation never occurs in the living 

 animal body. 



The bacillus is aerobic, yet it will grow at the bottom of a stick 

 culture in solid media. It fails to grow in an atmosphere of CO,, 



