At the present time there is ample evidence to show that tuberculin is the
most reliable means of detecting tuberculosis in the living animal and that
its use is not attended by any harmful aftereffects.

An act of Congress was approved July 24, 1919, for the purpose of
controlling and eradicating tuberculosis of animals. The official means of
detecting tuberculosis in the living animal is the tuberculin test, which
may be applied by three different methods--the subcutaneous, the
intradermic, and the ophthalmic. It is not necessary to discuss here the
details of these three methods, which are made use of in the work of
eradication of tuberculosis.

The plan adopted by the State and Federal authorities in eradication of the
disease is known as "The Accredited-Herd Plan." Under this plan herds are
tested under State and Federal supervision, the diseased animals are
appraised, removed, and slaughtered under Federal inspection. Retests are
then made after definite periods of time until two successive tests show
all the animals to be free from the disease. At this time the herd owner is
given a certificate of an accredited herd.

Details concerning the accredited-herd plan may be obtained by applying to
the Chief of the Bureau of Animal Industry, Washington, D. C.

THE TUBERCULIN TESTS.

Testing animals with tuberculin is the process of introducing tuberculin
into the animal and interpreting results according to well-known
standards.

From the investigations and observations that have been mentioned, it may
be safely concluded--

1. That the tuberculin test is a wonderfully accurate method of
determining whether an animal is affected with tuberculosis.

2. That by its use the animals diseased with tuberculosis may be detected
and removed from the herd, thereby eradicating the disease.

3. That it has no injurious effect upon healthy cattle.

4. That the comparatively small number of cattle which have aborted,
suffered in health, or fallen off in condition after the test were either
diseased before it was made or were affected by some cause other than the
tuberculin.

THE SUBCUTANEOUS TEST (UNDER THE SKIN).

The most frequently used method of testing is the subcutaneous test, which
consists in injecting the proper quantity of tuberculin underneath the skin
into the subcutaneous tissue. If an animal is tuberculous, the action of
the tuberculin causes a fever, which is indicated by a rise in temperature.
This