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 Davaine 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. 
