IMMUNITY IN TUBERCULOSIS. 
By Simon FLexner, M. D., 
Rockefeller Institute for Medical Research, New York City. 
I can not begin this address without delaying a moment to testify 
to my sense of the great honor which has been conferred upon me 
by your invitation. Neither can I proceed with it until I have ex- 
pressed to you my conviction that there are persons present in this 
audience whose scientific work on tuberculosis makes them far abler 
than I to discuss the complex problem of immunity in tuberculosis. 
My work in bacteriology in the past has not led me to an especial 
consideration of the highly important problem of the prevention and 
cure of tuberculosis, and I can therefore account in no other way for 
my selection to address you this evening than that you desired this 
topic presented to you from the point of view of one who has done 
some work in the general field of bacteriology. 
The modern study of tuberculosis, as you know, begins with the 
generation which immediately preceded the epoch-making discoveries 
of Koch. It may, I think, be said with justice that this study was 
inaugurated by the first purposeful transmission by inoculation of the 
disease from animal to animal. For whatever may have been the 
speculations upon the infectious and transmissible character of the 
disease before this demonstration, yet the demonstration was neces- 
sary before further steps in the elucidation of the cause and preven- 
tion of the disease could be taken. Koch in his masterful monograph 
gives the credit of successful inoculation to Klencke, who in the year 
1843 succeeded in inducing an extensive tuberculosis of the lungs and 
liver in rabbits by inoculation with portions of miliary and in- 
filtrating tubercles from man. LKlencke, after accomplishing this 
result, did not continue his investigations, and they were consequently 
soon forgotten. In the meantime Villemin’s experimental investiga- 
@ Address delivered at the joint meeting of the Association of American 
Physicians and the National Association for the Study and Prevention of 
Tuberculosis, held at Washington, D. C., May 16, 1906. Reprinted, by per- 
mission, from the transactions of the second meeting of the National Associa- 
tion for the Study and Prevention of Tuberculosis, 1906. 
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