IS TUBERCULIN, AS ORDINARILY USED, TOO DELICATE A TEST? 
55 
getting the disease under control. During the past fifteen 
months I have had considerable experience in testing with 
comparative doses of tuberculin. The result has been that my 
belief has been shaken seriously in regard to some of the com¬ 
monly accepted theories about the action of this substance, but 
I have also discovered what I think may be of practical and 
monetary importance in getting under control and finally stamp¬ 
ing out the disease tuberculosis. 
Before going further let me explain that when I speak of 
tuberculin I refer to Tibbertz Tuberculinum Kochii. By a small 
dose I mean two thirds of a minim ; a large dose, the ordinary 
one of from three to five minims. I will begin by stating what 
I believe to be the relative merits of testing with small and 
large doses and then endeavor to show grounds for what I say. 
1. A small dose of tuberculin will detect the worst and every 
dangerous case in a herd. I know of only one exception to this 
rule. 
2. A small dose will cause reaction in very advanced cases, 
where a large dose fails to react or at most only causes an 
attack of extreme prostration without any elevation in temper¬ 
ature. 
3. A small dose will not, as a rule, cause reaction in the 
earliest stages or in cases that are but slightly advanced. 
4. A small dose will not cause reaction in cases that have 
been slightly diseased and that may be said to have recovered. 
5. While small doses will not at once detect every case in a 
herd, yet by annual or semi-annual tests dangerous cases can 
be detected as they develop, and this coupled with proper sani¬ 
tary and hygienic regimen ought in time to result in the practi¬ 
cal extinction of the disease. 
It is a commonly accepted belief that when a badly diseased 
subject fails to react it is because her system is already so satu¬ 
rated with the poison that the addition of a little more does not 
make any serious difference. This must surely be a mistake. I 
have found it time and again that a dose of two-thirds minim 
(Koch’s) will cause a considerable reaction in cows that are ex- 
