314 ANTHRAX. 



ignorance. Be this as it may, the results detailed open up a 

 way for our arriving at an idea of the true pathology of the 

 disease. The bacilli in all parts of the body, whether directly 

 or intermediately by ferments, produce bodies toxic to tissue 

 cells. Further, bacilli confined locally produce by this means 

 effects on distant tissues. This explains how in certain cases, 

 while the bacilli are still locally confined, there may occur 

 oedema spreading from the pustule, and pyrexia. 



The Spread of the Disease in Nature. — We have seen that 

 the B. anthracis rarely, if ever, forms spores in the body, and if 

 the bacilli could be confined to the blood and tissues of carcases 

 of animals dying of the disease, it is certain that anthrax in an 

 epidemic form would rarely occur. For it has been shown by 

 many observers that in the course of the putrefaction of such a 

 carcase the anthrax bacilli rapidly die out, and that after ten 

 days or a fortnight very few remain. But it must be remem- 

 bered that while still alive, an animal is shedding into the air by 

 the bloody excretions from the mouth, nose, and bowel, myriads 

 of bacilli which may rapidly spore, and thus arrive at a very re- 

 sistant stage. These lie on the surface of the ground and are 

 washed off by surface water. At certain seasons of the year 

 the temperature is, however, sufficiently high to permit of their 

 germination, and also of their multiplication, as they can un- 

 doubtedly grow on the organic matter which occurs in nature. 

 They can again form spores. It is in the condition of spores 

 that they are dangerous to susceptible animals. In the bacillary 

 stage, if swallowed, they will be killed by the acid gastric con- 

 tents; but as spores, they can pass uninjured through the 

 stomach, and, gaining an entrance into the intestine, infect its 

 wall, and ultimately reach, and multiply in, the blood. It is 

 known that in the great majority of cases of the disease in 

 sheep and oxen, infection takes place thus from the intestine. 

 It was thought by Pasteur that worms were active agents in the 

 natural spread of the disease by bringing to the surface anthrax 

 spores. Koch made direct experiments on this point, and could 

 get no evidence that this was the case. He thinks it much 

 more probable that the recrudescence of epidemics in fields 

 where anthrax carcases have been buried is due to persistence 

 of spores on the surface which has been infected by the cattle 

 when alive. 



