126 The American Naturatst. 
_riously affected. From these researches I in the meantime do 
not draw any further conclusions than that the possibility of ren- 
dering pathogenic bacteria in the living body harmless without 
injury to the latter, which has hitherto been justly doubted, has — . 
been thereby established.” (Address before the Medical Con- 
gress in Berlin, August, 1890.) 
It will be observed that Professor Koch in his paper makes 
two points: 1st, The action of solar light and a high degree of ; 
heat in destroying the virulence of the microbe; 2d, The fact 
that he had produced a substance the effect of which was to 
prevent the growth of the tubercle bacilli in the body of an 
animal, and that he produced a condition in that animal that was- 
immune to the virulent tubercle bacilli; also that he by the same 
process could overcome tuberculosis already established. 
[February, ; 
There are also two facts that cannot fail to strike the observer. : 
The first is, that a period of over seven years had elapsed from 
the date of his first publication on the tubercle bacillus and that 
_announcing his discovery of the toxic agen 
that his researches after the substance must 
t; and the second, 
have commenced 
about the period of Dr. Dixon's publication of October, 1889, of ; a 
which, however, no mention is made in his address. It dos 
not seem unfair to infer that Professor Koch had been mam 
this substance, 
therefore, although they have occupied me for nearly a yeah 
cessful during the preceding years in arriving at any sati 
results. His own words, “ My researches on 
ver, popos® 
etc., seems conclusive on this point. We do not, howe 
to do more than call attention to the coincidence of his r pgs 
after the toxic agent and the publication of Dr. Dixon’s, OC re 
1880, the importance of which would be obvious to iy mE 
ologist, and the unfruitful nature of the former’s investigati 
previous to that date. : aa 
There was, perhaps, a feeling prevalent in the medical wT 
incompleteness in the terms of Professor Koch’s announce” 
and it seems as if he had only stimulated curiosity in order 
deny it satisfaction. Nor was this allayed when the ee l 
from Berlin that the scientist, having brought his researche 
point sufficiently advanced to justify the use of his E 
a, o 
