46 STORRS AGRICULTURAL EXPERIMENT STATION. 
Injurious Effects of Tuberculin.—It has been, from the 
first, thought by some that the use of tuberculin produces a 
direct injury upon the inoculated animals. This, however, is 
undoubtedly a mistake, and there is no longer any belief any- 
where on the part of scientists that the injury thus produced is 
worthy of note. In the first place, the idea that it may pro- 
duce the disease in a perfectly healthy animal by the inoculation 
is absolutely fallacious. The tuberculin does not contain the 
tubercle bacillus, and it is absolutely certain that it is impos- 
sible to produce a case of tuberculosis in an animal unless the 
tubercle bacilli are present. ‘The use of tuberculin, therefore, 
certainly can never produce the disease in the inoculated 
animal. 
It has been more widely believed, however, that the inocu- 
lation of an animal with this material has a tendency to stimu- 
‘late an incipient case of tuberculosis. It has been thought 
that an animal with a very slight case of the disease may, after 
inoculation, show a very rapid extension of this disease and 
be speedily brought to a condition where it is beyond any use. 
The reasons given for this have been the apparent activity of 
the tuberculous infection in animals that have been slaughtered 
shortly after inoculation. This has been claimed, not only by 
agriculturists who have not understood the subject well, but 
also by veterinarians and bacteriologists. But here, too, we 
must recognize that the claim has been disproved, and that 
there is now a practical unanimity of opinion on the part of all 
who are best calculated to judge, that such an injurious effect 
. does not occur. Even those who have been most pronounced 
in the claim that there is injury thus resulting from tuberculin 
have little by little modified their claim, until at the present 
time they say either that the injury which they formerly 
claimed does not occur, or that the stimulus of the disease is 
so slight that it should be absolutely neglected, in view of 
the great value which may arise from the use of tuberculin. 
Apart from two or three who hold this very moderate opinion, 
all bacteriologists and veterinarians unite in agreeing that 
there is no evidence for believing that any injury results. In 
Denmark, especially, many hundreds of thousands of animals 
have been inoculated, and the veterinarians say there is abso- 
lutely no reason in all their experience for believing that the 
tuberculin inoculation is followed by any injurious results. 
Abuse of Tuberculin. —It is certain that the use of tuber- 
culin is subject to abuse. The abuse, however, arises rather 
