BACILLUS ANTHRACIS AND ANTHRAX 781 



able to multiply in the blood. At the place of inoculation and 

 probably in the organs they proliferate, until the resistance of the 

 infected subject is entirely overcome. At this stage of the disease, 

 no longer held at bay by any antagonistic qualities of the blood, 

 they enter the circulation and multiply within it. Autopsy upon 

 such animals reveals an edematous hemorrhagic infiltration at the 

 point of inoculation. The spleen is enlarged and congested. The 

 kidneys are congested, and there may be hemorrhagic spots upon 

 the serous membranes. The bacilli are found in large numbers in 

 the blood and in the capillaries of all the organs. 



The mode of action of Bacillus anthracis is as yet an unsettled 

 point. It is probable that death is brought about to a large extent 

 by purely mechanical means, such as capillary obstruction. Neither 

 a true secretory toxin nor an endotoxin has been demonstrated for 

 the anthrax bacillus. The decidedly toxemic clinical picture of the 

 disease, however, in some animals and in man, precludes our 

 definitely concluding that such poisons do not exist. It is a matter 

 of fact, however, that neither culture filtrates nor dead bacilli have 

 any noticeable toxic effect upon test animals, and exert no appre- 

 ciable immunizing action. 



Spontaneous infection of animals takes place largely by way of 

 the alimentary canal, the bacilli being taken in with the food. The 

 bacteria are swallowed as spores, and therefore resist the acid gastric 

 juice. In the intestines they develop into the vegetative forms, 

 increase, and gradually invade the system. The large majority of 

 cattle infections are of this type. Direct subcutaneous infection 

 may also occur spontaneously when small punctures and abrasions 

 about the mouth are made by the sharp spicules of the hay, straw, 

 or other varieties of fodder. 



When infection upon a visible part occurs, there is formed a 

 diffuse, tense local swelling, not unlike a large carbuncle. The 

 center of this may be marked by a black, necrotic slough, or may 

 contain a pustular depression. 



Infection by inhalation is probably rare among animals. Trans- 

 mission among animals is usually by the agency of the excreta or 

 unburned carcasses of infected animals. The bacilli escaping from 

 the body are deposited upon the earth together with animal and 

 vegetable matter, which forms a suitable medium for sporulation. 

 The spores may then remain in the immediate vicinity, or may be 

 scattered by rain and wind over considerable areas. The danger 



