ANTHRAX. 339 



Davaine made a further study of the organisms in the blood, 

 and advanced the theory that they were the cause of the 

 disease. By a series of experiments and observations he ren- 

 dered it probable that his theory was correct, although he did 

 not demonstrate it. From the publication of Davaine's con- 

 clusions the subject was vigorously disputed, the conservative 

 students denying that the bacilli had anything to do with the 

 disease. The difficulty of demonstrating the theory lay along 

 t\vo different lines. In the first place, organisms were found 

 elsewhere in nature which looked, under the microscope, pre- 

 cisely like those found in the anthrax blood, but which had no 

 power of producing the disease. Not recognizing that these 

 microscopic bacteria might look the same and yet be totally 

 different, the objectors to Davaine's views insisted that the 

 presence of similar organisms in water, which would not pro- 

 duce this disease, disproved the theory. Secondly it was 

 found very difficult to obtain the anthrax bacilli in a pure 

 enough condition to demonstrate that they alone could pro- 

 duce the disease. A drop of blood containing them was cap- 

 able of producing infection, but such a drop of blood evidently 

 contained something besides these bacteria, and it might have 

 been something else that caused the disease. In those early days 

 of bacteriological study it was recognized that the only proof 

 of a disease being caused by a definite organism, was to obtain 

 the organism separate by itself, and then, by inoculation, to show 

 that it could produce the disease in a healthy animal. Such 

 a pure culture could not be obtained satisfactorily and, there- 

 fore, the proof of the theory of Davaine waited for some years. 

 It was Professor Koch who, in 1875, first succeeded in get- 

 ting pure cultures of the bacillus in such a manner as to enable 

 him to study it carefully and to demonstrate its power of pro- 

 ducing anthrax in healthy animals. His work was followed 

 almost at once by work of Pasteur who, apparently in igno- 

 rance of the experiments of Koch, undertook the investigation 



