ANTHRAX. 123 



(2) By the skin. — When infection is introduced through 

 the skin, there results the condition known as external anthrax, 

 carbuncular disease, inoculation anthrax, or malignant pustule. 

 This may be occasioned by insects, especially the blood-sucking 

 varieties as the different horse or gad-flies (Tabanidae), prob- 

 ably, also, by some varieties of the mosquito; by wounds made 

 by infected instruments or utensils; or other wounds coming in 

 contact with virulent material. In the Lower Mississippi Valley 

 the external form occurs very frequently, and some outbreaks 

 extend over considerable territory, among horses and mules on 

 account of the vast numbers of horse flies during the summer 

 months. 



• "^-.» 



FIG. 48. BACTERIUM (BACILLUS) ANTHRACIS. (If. H. R.) 

 The specific cause of anthrax. 



(3) By the digestive tract. — The internal, or intestinal form 

 of anthrax is generally produced through taking the virus in 

 contaminated food or water. 



Herbivorous animals contract the disease through grazing 

 over infected pastures, or through cured products raised upon 

 infected fields. 



Hogs suffer through eating the flesh of animals that have 

 died of the disease. 



Poultry have been observed to die, during epizootics in some 

 of the Gulf States, after eating portions of anthrax flesh and 

 offal ; and have, also, been observed to succumb suddenly, and 

 several at a time, after picking off, and eating, horse-flies from 

 the bodies of mules affected with anthrax. The blood in these 

 cases was. however, not examined microscopically. 



Methods of introduction and spread. — Imported hides, hair, 

 wool, etc., from foreign countries infected with anthrax. Fer- 

 tilizing materials manufactured from animals affected with the 

 disease may be a source of infection. Running water may be- 

 come contaminated, and spread infection along its course. The 

 refuse water from tanneries has been known to disseminate in- 

 fection from anthrax hides. The wind mav sometimes be re- 



