1891. Editorial, 125 
Drs. Von Pettenkofer, Koch, Louder-Brunton, and other scientific 
investigators. 
The International Medical Congress was appointed to meet in 
Berlin in August, 1890, and more than usual interest attached to 
its meeting, as it was generally rumored that some important 
papers on the subject of the tubercle bacillus would be read on 
that occasion. | 
Nor was this rumor falsified, and the interest of the meeting 
may be said to have culminated as Professor Koch rose to ad- 
dress the assembled physicians, and when he stated that he had 
hit upon a substance which had the power of preventing the 
growth of the tubercle bacillus, it was greeted with loud applause. 
It was then stated that the bacillus of tuberculosis in man and 
chickens was very similar, and he inferred that the latter is a 
special species of the organic matter supposed to lie at the root 
of pulmonary consumption. He also announced that the direct 
action of solar light on the tubercle bacillus destroys in a cer- 
tain length of time, varying from a few minutes to several hours, 
the virulence of this microbe. 
It will be convenient to quote verbatim from that portion of 
the paper proclaiming his discovery of a toxic agent: “In spite 
of this failure—to effect any result on tuberculous animals with 
chemical substances—I have not allowed myself to be discouraged 
from prosecuting the search for growth-hindering remedies, and 
I have at last hit upon a substance which has the power of pre- 
venting. the growth of tubercle bacilli, not only in a test tube, but 
in the body of an animal. All experiments in tuberculosis are, 
as every one who has had experience of them has sufficiently dis- 
covered, of very long duration. My researches on this substance,. 
therefore, although they have already occupied me for nearly a 
year, are not yet completed, and I can only say this much about 
them, that guinea-pigs, which, as is well known, are extraordi- 
narily susceptible to tuberculosis, if exposed to the influence of 
this substance, cease to react to the inoculation of tuberculous 
virus, and that in guinea-pigs suffering from general tuberculosis,. 
even to a high degree, the morbid process can be brought com- 
pletely to a standstill without the body being in any way inju- 
