NINTH ANNUAL YEAR BOOK— PART X 473 
sidered as tuberculous and that when a careful clinical examination is 
practiced in addition to the test there are few animals in a dangerous 
condition which escape detection. 
The first questions asked by those who oppose the adoption of the tu- 
berculin tests are: Is this test infallible? and, if it is not infallible, why 
should it be forced upon the cattle owners of the country? 
In answer to these questions it may be said that tuberculin is not ab- 
solutely infallible, and yet it is by far the best method of diagnosing 
tuberculosis that has been discovered. It is much better than any test 
known for pleuro-pneumonia when that disease was eradicated. 
Practically all the animals that react are affected with tuberculosis 
and should be separated from the herd, not only in the interest of the 
public but in the interest of the owner of the herd. The best authorities 
admit, after studying many thousands of tests, that there are few, if any, 
mistakes made in condemning cattle which show a typical tuberculin 
reaction. The errors are principally in the other direction — that is, some 
tuberculous animals are not discovered by the tuberculin test, but as the 
most dangerous of these may be picked out by ordinary clinical examina- 
tion the fault of tuberculin is not so serious as it at first sight appears. 
This being the case, it should not be necessary to force the tuberculin 
test upon owners. They should be anxious to adopt it in their own in- 
terests and for the protection of their patrons. There is today no 
greater danger to the cattle and hog industries ti^an that which confronts 
them in the form of tuberculosis, a disease already widespread and rap- 
idly extending. Furthermore, tuberculin must be considered as harmless 
for healthy animals in view of the results revealed by numerous tests 
covering vast numbers of animals. And it has also been clearly demon- 
strated that tuberculin interferes in no way with the milking function in 
healthy cattle; neither in the quantity of milk nor in butterfat value 
has any variation been detected. The conclusions of some of the best 
authorities on the subject of its harmlessness to healthy animals are 
given below. 
Norcard and Leclainche state: 
"Direct experiments and observations collected by thousands show that 
the tuberculin injections have no unfavorable effect. With healthy ani- 
mals the system is indifferent to the inoculation; with tuberculous animals 
it causes slight changes w^hich are not at all serious." 
Bang has written as follows on this question: 
"We will now consider the following question, a very important one, 
in the application of tuberculin, viz.: Can the reaction produce a worse 
condition in tuberculous animals than before existed? Hess emphatically 
states that it can, and on this account he earnestly warns against its 
application. My attention has been directed to this question from the 
beginning. In my first publication on tuberculin injection I reported two 
cases in w^hich acute miliary tuberculosis was proved in two high-grade 
tuberculous cows several weeks after the tuberculin injection. I then 
stated my suspicion that perhaps the tuberculin injection had some con- 
nection with this, just as is often supposed to be the case in human 
practice. With my present very large amount of material for observa- 
