THE TUBERCULIN TEST FOR TUBERCULOSIS IN MILCH COWS. 389 
in nearly every case the value of this product of the bacillus 
tuberculosis^ as a diag’irostic agent, has been confirmed. The 
technique of the mannfactnre of tnbercnlin may be omitted 
here ; suffice to say that it is the toxic product of the germ of 
consumption, and improperly prepared contains none of the 
bacilli themselves. It can, therefore, in.no case induce, cause 
or transmit the disease in any form. Tnbercnlin is simply a 
chemical constitnent, an inanimate substance, and cannot in¬ 
crease itself in the animal body as a living micro-organism has 
the power to do. 
Prof. Bang, of Copenhagen, Denmark, a close student of 
animal tnbercnlosis for many years, has, since 1891, been try¬ 
ing to eradicate the plague from that little kingdom of 2,000,000 
souls and 1,960,000 cattle. In his battle with grim phthisis, this 
agent alone, he says, has placed him in a position to discover 
tnbercnlosis in its hidden forms. Since he began his work 
535303 cattle have been subjected to the tnbercnlin test, of 
which 20,665 reacted, and were found tnbercnlons. The effect 
of tnbercnlin upon tubercular cattle, as to whether their con¬ 
dition was made worse or not by its use, has often been ques¬ 
tioned. To determine this point Dr. Bang made post-mortems 
on 83 tubercular animals that had been subjected to repeated 
tuberculin tests. Notwithstanding that among these 83, which 
were affected in a high degree, in only 4 cases was an acute 
miliary (embolic) tuberculosis apparent. Even a localized tuber¬ 
culosis was not made general, in spite of the fact that the cows 
had been tested several times. We must also bear in mind 
in this connection that a chronic tuberculosis can at any time 
become an acute miliary one and lead to a hasty death. 
Tuberculin is not an infallible agent. We are at times led 
by its use to make a false diagnosis. These false diagnoses are 
' of two kinds : either the tuberculin causes a reaction where the 
animal is not tuberculous, or there is no rise of temperature 
when the disease is present. 
Dr. Hber recently made autopsies upon 503 animals con¬ 
demned as being tubercular with the tuberculin test. The 
f 
