454 
J. F. WINCHESTER. 
elevation of the temperature. The minute quantity which will 
not affect a healthy animal, when injected into a slightly tuber¬ 
culous one, will, in from 8 to 36 hours, cause a decided rise in 
temperature, The explanation of this is that the system con¬ 
tains tuberculin produced by the disease, to which the animal 
has become so accustomed that it cannot be detected by any 
clinical test. When the small amount of tuberculin used for 
the test is introduced into the circulation, it increases the activity 
of the disease process, and as a result the temperature of the 
body is elevated. From this fact it is evident that the quantity 
of tuberculin to be used ought to vary with each animal, but 
experiments and observation have demonstrated that for ordinary 
size coavs, a certain amount (25 cc.) can be relied upon for 
positive results in occult cases. Cases may occur in which the 
temperature of a coav will rise after the injection of tuberculin 
and still the animal is not tuberculous. Any febrile disturbance 
may set in after the injection, the period of heat or bulling, 
close approach to parturition, active exertion, exposure, too hot 
sun, confinement in close building or privation of water. 
It is evident from these facts that only the trained veterina¬ 
rian should use tuberculin, and he must always be on his guard 
not to mistake any febrile disturbance that might arise other 
than would occur by the use of tuberculin in the tuberculous. 
Laying aside these and other causes of error in unskilled hands, 
the elevation of the temperature should not condemn tuberculin, 
but stimulate a search for occult tubercles, and a failure will be 
rare. 
There are cases where the animal is tuberculous and the 
injection of tuberculin will not cause any febrile reaction. In 
such animals the system is saturated with tuberculin and the 
small amount injected will not make an impression. These 
cases are readily diagnosed by a physical examination. A re¬ 
action will take place even in the slightest case of tuberculosis 
by the use of tuberculin, and many of the animals would live 
for years and might recover. For this reason, when it is desira¬ 
ble to dispose of the diseased animals, or to exclude from a herd 
