340 AGRICULTURAL BACTERIOLOGY. 



by quite a different method. Pasteur's work was of a more 

 striking character than that of Koch, and a few years later, in 

 connection with this very disease, Pasteur made an epoch-mak- 

 ing discovery of a method of preventing it. For this reason 

 his name has been intimately associated with the disease even 

 though he was not the first, either to discover its cause, or to 

 demonstrate the causal relation of the bacillus and the dis- 

 ease. Both Koch and Pasteur succeeded in obtaining a pure 

 culture of the bacilli, Koch by the use of a special culture 

 medium made of the aqueous humor from the eye, and Pasteur 

 by the simple method of dilution produced by successive inoc- 

 ulations. Finding that the bacillus would grow in a solution 

 made by steeping yeast in water, Pasteur inoculated a flask of 

 such yeast water with a drop of anthrax blood. In a day or 

 two his flask was filled with the bacilli which had arisen from 

 the first by division. The inoculation of a second flask from 

 the first showed like results, and, by continuing such inocula- 

 tions from flask to flask, he rapidly got rid of all parts of the 

 original drop of blood except such parts as had been multiply- 

 ing in the flasks. His microscope showed him that the only 

 thing that multiplied and remained in his later flasks was the 

 bacillus which was present in the original drop of blood. In 

 this way he obtained a culture of the bacillus, free from every 

 trace of the original drop of blood. Nevertheless he found 

 that though he continued these inoculations indefinitely, every 

 flask was equally fatal, and a small drop of the culture would 

 inevitably produce anthrax in a susceptible animal in a very 

 few hours, the development of the disease being always ac- 

 companied by the growth of the bacilli in its blood in count- 

 less myriads. These results left no loop hole for criticism, 

 proved that this bacillus was the cause of anthrax, and thus 

 for the first time demonstrated that an infectious disease was 

 produced by a bacterium multiplying within the body of the 

 animal in which it grows as a parasite. 



