BOBERT KOCH. 653 



Koch's interest in traumatic infectious diseases seems to have been 

 stimulated by the disasters due to these causes among the wounded 

 in the Franco-Prussian War. The results of Lister's antiseptic 

 methods had demonstrated that means directed against the infec- 

 tion of wounds with microbes obviated these diseases. Micrococci 

 and bacteria had frequently been found in pus, diphtheritic ulcera- 

 tion, in the tissues at the edge of advancing erysipelas, and in pysemic 

 deposits. Microorganisms had also been discovered in the blood of 

 relapsing fever and puerperal fever. Further, Coze and Feltz and 

 Davaine had inoculated rabbits with the blood of patients dead of 

 puerperal fever, and had succeeded in carrying on the infection 

 through successive generations of these animals. Nevertheless, the 

 evidence that a particular organism was the cause of a particualr 

 disease was far from conclusive. Many observers concluded that 

 bacteria were universally present in the normal body. . Others failed 

 to find any organisms in obviously septic conditions. There was no 

 practicable means of separating one coccus from another coccus, and 

 bacteria of identical appearance were found to be associated with a 

 variety of diseases. The parasitic nature of traumatic diseases was 

 probable, but unproven. 



Koch began his work on traumatic infective diseases with the con- 

 viction that the most fruitful line of investigation would be a com- 

 parative one, namely, to induce septic infections in animals and see 

 whether they would " breed true" upon successive reinoculations, 

 controlling the experimental observations by careful microscopic 

 examination throughout. He used for the purpose of infecting his 

 animals putrid serum or bouillon. This, he found, contained a large 

 variety of organisms of different sizes and shapes, which he was 

 unable to separate from one another. He hoped that, implanted 

 into the body of an animal, a selection might occur, and only those 

 pathogenic for the particular species survive. His anticipations were 

 justified, and the injection of small quantities of such materials was 

 followed, in a number of instances, by the development of a fatal 

 illness with the presence in the blood of one only of the many forms 

 present in the original material. He was able to carry on the disease 

 from one animal to another, always with the same symptoms and the 

 presence of the same organism. Moreover, if the same material con- 

 taining a variety of organisms were injected into animals of different 

 species, one microbe flourished in the one species and another in the 

 second, showing that a particular microbe could establish itself in one 

 animal and not in a neighboring species. 



The animal body is, as Koch said, an excellent apparatus for pure 

 cultivation, and he succeeded to some extent in doing what had been 

 the stumbling block to all progress, namely, to isolate one organism 

 from another. 



