4 6 4 PATHOGENIC BACTERIA. 



tective inoculation by Pasteur's method has diminished 

 the death-rate from 10 per cent, for sheep and 5 per 

 cent, for cattle to about 0.94 per cent, for sheep and 0.34 

 per cent, for cattle, so that the utility of the method is 

 scarcely questionable. In 1890, Ogata and Jasuhara 

 showed that in the convalescents from anthrax among 

 their experimental animals an antitoxic substance was 

 present in the blood in such quantities that 1 : 800 parts 

 per body-weight of dog's serum containing the antitoxin 

 would protect a mouse. Similar results have been at- 

 tained by Marchoux. 



Experiments of interest have been performed to show 

 that the natural immunity enjoyed by many animals can 

 be destroyed. Behring found that if the alkalinity of the 

 blood of rats was diminished, they could become affected 

 with anthrax, and numerous observers have shown that 

 when anthrax bacilli and unrelated organisms, such as 

 the erysipelas cocci, Bacillus prodigiosus, and Bacillus 

 pyocyaneus, are simultaneously introduced into immune 

 animals, the immunity is destroyed and the animals 

 succumb to the disease. Frogs have been made to suc- 

 cumb to the disease by exposure to a temperature of 37 

 C. after inoculation. Pasteur destroyed the immunity of 

 fowls by a cold bath after inoculation. 



In the natural order of events anthrax in cattle is 

 probably the result of the inhalation or ingestion of the 

 spores of the bacilli from the pasture. At one time 

 much discussion arose concerning the infection of the 

 pasture. It was argued that, the bacilli being enclosed 

 in the tissues of the diseased animals, the infection of 

 the pasture must be due to the distribution of the germs 

 from the buried cadaver to all parts of the field, either 

 through the activity of earth-worms, which ate of the 

 earth surrounding the corpse and then deposited the 

 spores in their excrement at remote areas (Pasteur), or to 

 currents of moisture in the soil. Koch seems, however, 

 to have demonstrated the fallacy of the theories by show- 

 ing that the conditions under which the bacilli find them- 



