THE BACILLUS OF SYMPTOMATIC ANTHRAX 391 



naturally immune to the disease. - The guinea-pig is the most suscept- 

 ible of test animals. When susceptible animals are inoculated subcu- 

 taneously with pure cultures of this organism, or with spores attached 

 to a silk thread, or with bits of tissue from the affected parts of another 

 animal dead of the disease, death ensues in from twenty-four to thirty- 

 six hours. At the autopsy a bloody serum is found in the subcutaneous 

 tissues, extending from the point of inoculation over the entire surface 

 of the abdomen, and the muscles present a dark-red or black appear- 

 ance, even more intense in color than in malignant oedema, and there 

 is a considerable development of gas. The lymphatic glands are mark- 

 edly hypersemic. 



The disease occurs chiefly in cattle, more rarely in sheep and goats; 

 horses are not attacked spontaneously i. e., by accidental infection. 

 In man infection has never been produced, though ample opportunity 

 by infection through wounds in slaughter-houses and by ingestion of 

 infected meat has been given. The usual mode of natural infection 

 by symptomatic anthrax is through wounds which penetrate not only 

 the skin, but the deep, intercellular tissues; some cases of infection by 

 ingestion have been observed. The pathological findings present the 

 conditions above described as occurring in experimental infection. 



DISTRIBUTION OUTSIDE OF THE BODY. Symptomatic anthrax, like 

 anthrax and malignant oedema, is a disease of the soil, but it shows a 

 more limited endemic distribution than the former, and is differently 

 distributed over the earth's surface than the second of these diseases, 

 being confined especially to places over which infected herds of cattle 

 have been pastured. It is doubtful whether the bacilli are capable 

 of development outside of the body like anthrax. In the form of spores, 

 however, reproduction may take place; and by contamination with 

 these, through deep wounds acquired by animals in infected pastures, 

 the disease is spread. 



TOXINS. Under favorable conditions extracellular toxins are formed 

 so that the filtrate of cultures is very poisonous. Injections of the 

 toxin into animals excite the production of antitoxins. 



To recapitulate briefly, the principal points for differentiating this 

 bacillus from the bacillus of malignant oedema, which it closely resem- 

 bles, are: it is smaller; it does not develop into long threads in the 

 tissues; it is more actively motile, and forms spores more readily in the 

 animal body than does the bacillus of malignant oedema. It is patho- 

 genic for cattle, while malignant oedema is not; and swine, dogs, rabbits, 

 chickens, and pigeons, which are readily infected with malignant oedema, 

 are not, as a rule, susceptible to symptomatic anthrax. 



PREVENTIVE INOCULATIONS. It is well known to veterinarians that 

 recovery from one attack of symptomatic anthrax protects an animal 

 against a second infection. Artificial immunity to infection can also be 

 produced in various ways: by inoculations with cultures which have 

 been kept for a few days at a temperature of 42 to 43 C. and 

 have thus lost their original virulence, or by inoculations of filtered 

 cultures, or of cultures sterilized by heat. For the production of 



