128 SYMPTOMATIC ANTHRAX 



directly about the site of injection. At first the edematous areas are 

 soft and pasty ; later gas accumulates and they become crepitant. This 

 continues for from twenty-four to forty-eight hours, when the ani- 

 mal shows agonal breathing and dies either in convulsions or coma. 

 In certain instances the development of the infection is atypical. It 

 proceeds less rapidly, leads to the formation of an abscess and ulti- 

 mately ends in recovery. On necropsy the subcutaneous tissue is found 

 impregnated with bloody fluid and distended with gas. In the serous 

 cavities, pleura, peritoneum and pericardium, there are exudates, more 

 or less stained with blood and often coagulated. The heart is soft and 

 distended ; the liver and kidneys hyperemic ; the lungs anemic ; and the 

 spleen normal in size. This is practically the symptomatology of the 

 disease in cattle. Young animals are most susceptible and die within 

 a few hours after the first indication of being ill. The disease is widely 

 distributed and has been the cause of great commercial loss. It is most 

 prevalent during the summer and early fall and in low-lying meadows 

 and along water courses. Just how animals become infected is not 

 known, but it is generally supposed that the virus finds entrance 

 through some accidental wound. To one who has seen herds of calves 

 die within a few days from this disease, this explanation is not wholly 

 satisfying. It is not probable that all the animals in the herd, or even 

 a large percentage of them, carried accidental wounds at the same 

 time. No insect has been convicted of this crime up to the present 

 time. The infection is not transmitted by feeding and, strange to say, 

 animals bear without infection large intravenous injections of pure 

 cultures, provided that none of the fluid finds its way into the sub- 

 cutaneous tissues. 



While epidemics have been observed only in cattle, possibly a few 

 in hogs, many animals are susceptible to direct inoculation into the 

 subcutaneous or muscular tissue. Rabbits, white rats, and mice are 

 refractory, but may succumb to large inoculations. 



The bacillus grows best on a medium containing an emulsion of 

 brain tissue. As has been stated, it does not grow in the presence of 

 oxygen and deep intramuscular injections are more certainly fatal 

 than subcutaneous ones. Injections into serous cavities are generally 

 without effect. Bacilli introduced into these cavities are speedily 

 devoured by the phagocytes. When injected with lactic acid, which 



