MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 751 



as in the deltas of the Mississippi and Bramaputra, and the dis.ease is 

 also common along the banks of many rivers (Vistula, Rhine, Seine, 

 etc.). 



The anthrax organism is a large, non-motile rod, from S;u to lOiU long and im to 

 i.SM broad. In cultures it frequently forms long threads or filaments (Fig. 156). 

 The free ends are slightly rounded, but those in contact are quite square, and 

 slightly larger in diameter than the middle of the cell. Involution forms are 

 obtained by culture on potato or at temperatures of 40° to 42°. It forms oval spores 

 without distortion of the mother cell (Fig. 157). Free oxygen is necessary for the 

 development of these bodies, and a temperature between 18° and 41°. Spore ger- 

 mination is polar. By culture at 42° an asporogenous variety is formed. It stains 



Fig. 156.— Bad. anthracis. Showing Pig. 157. — Bact. anthracis. Spore pro- 

 the thread formation of colony. {After duction. (After Migtda.) 



Kolle and Wassermann from Stitt.) 



readily with the aniline dyes and also by Gram's method. Under certain conditions 

 a capsule may be seen. The organism is aerobic, in the body it grows as a faculta- 

 tive anaerobe. Its optimum temperature is 37°, minimum 12°, maximum 45°. 

 It forms characteristic wavy and filamentous colonies on gelatin and agar, it liquefies 

 geiatin, produces an arborescent growth in gelatin stab cultures, coagulates and 

 peptonizes milk with an alkaline reaction. Thermal death-point of the spores in 

 liquids is four minutes at 100°, in hot air 140° for three hours. Mercuric chloride, 

 I : 1000, destroys the spores in a few minutes, and 4 per cent carbolic acid with 

 hydrochloric acid 2 per cent in one hour. 



Zoologically, anthrax is the most widespread of infectious diseases; 

 wliite mice, guinea-pigs, rabbits, sheep, cattle, horses and man are 

 susceptible. Old rats are insusceptible. Von Behring, Metchnikoff 



