MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 803 



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; 

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

 susceptible. Old rats are insusceptible. Von Behring, MetchnikofT 

 and others have shown that the serum of white rats contains a lysin 



FIG. 167. Bad. anthracis. Showing FIG. 168. Bad. antkracis. Spore pro- 

 the thread formation of colony. (After duction. (After Migula.) 



Kolle and Wassermann from Stitt.) 



capable of dissolving the bacterium in vitro. Pigs are occasionally 

 infected; the carnivora generally are refractory, the bear and cat 

 being less resistant. Most birds are insusceptible, but some small 

 birds, like the sparrow, are more susceptible. Cold-blooded animals 

 are refractory. 



Infection occurs: Through the food, giving rise to intestinal anthrax. 

 Cattle and sheep are usually infected in this manner by spores, the bac- 

 terium being destroyed by the gastric juice. In man infection through 

 food rarely occurs. 



Through the air. Infection by inhalation through the lungs occurs 

 in man through the medium of dust contaminated by anthrax spores, 

 hence the name "wool-sorter's disease." 



Through wounds. This method usually occurs in man and also in 

 sheep. Cutaneous infection comes through a scratch or wound, and 



