652 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 



ask of nature in order to advance one step further, but also to devise 

 experimental methods which insured an answer to this question. 

 In this last faculty Koch was preeminent, and the methods of this 

 youngest of the sciences are to a large extent the methods of Robert 

 Koch. 



Two of his earliest papers — that on the etiology of anthrax, 

 founded on the life history of Bacillus anthracis published in 1876, 

 and that on experiments on the etiology of wound infections, pub- 

 lished in 1878, written when district surgeon at Wollstein — have 

 become classics. This work was carried out in addition to the 

 duties of a practitioner of medicine, and without the assistance of 

 any laboratory equipment beyond a good microscope. Pollender 

 and Davaihe had seen the anthrax bacillus 20 years earlier in 

 the blood of infected animals, and in 1863 the latter had shown that 

 the blood containing the bacilli was capable of infecting animals, if 

 inoculated into them. That these bacilli were in reality the cause 

 of the disease was, however, controverted. Koch reasoned that as 

 the disease remained attached to certain pastures, if the anthrax 

 bacilli were the living virus, they ought to grow outside the body as 

 well as inside. He succeeded in cultivating many successive genera- 

 tions of them in broth, and also watched their growth upon a hot 

 stage. He discovered that they formed spores when grown outside 

 the body or when blood containing them was allowed to dry; deter- 

 mined the greatly increased resistance of the spores to physical and 

 chemical agents; and showed that as long, and only as long, as the 

 broth or dried material contained bacilli or spores capable of propa- 

 gating themselves, these remained infective for animals. 



The importance of the anthrax work can hardly be overestimated. 

 It afforded for the first time convincing proof of the causal relation 

 of a particular bacillus to a particular disease. Owing to the unmis- 

 takable character of the bacillus, and its presence in large numbers 

 in the blood of infected animals, its study could be profitably under- 

 taken with the means available. 



Koch was unremitting in his efforts to improve his microscopical 

 technique, and in the same year published a paper on the investiga- 

 .tion, preservation, and photographing of bacteria, in which an 

 account of the preparation and staining of dry films is given. The 

 method described is very much that still in daily use. The paper 

 is accompanied by photomicrographs of bacteria, the excellence of 

 which is rarely equaled at the present day. Koch pointed out that 

 he had persevered in this work because he was obsessed with the 

 idea that the hitherto conflicting results of investigations on the 

 causation of infective diseases had their foundation in the incom- 

 pleteness of the methods used. 



