rise, under ordinary conditions, may occur any time between the eighth
and twentieth hours after the tuberculin is injected, but in some cases it
is desirable to measure the temperature before the eighth hour and continue
to the twenty-fourth hour or longer.

The temperatures are measured at least 3 times in advance of the injection,
at 2-hour intervals, to learn whether the animal is in proper condition to
receive the test. The temperatures after injection are taken every 2 hours
until the test is completed. The proper interpretation of the temperatures
is made by the person applying the test, and a careful observance of any
clinical changes is always important in determining the result. It can not
be set forth too strongly that the test, including the two following
methods, should be attempted only by those who are properly qualified to do
the work.

THE INTRADERMIC TEST (INTO THE SKIN).

The intradermic test for detecting tuberculosis is used to a considerable
extent, especially in area work and on range cattle not easily controlled.
When made by those who have become skilled in its application, it is very
accurate. In this test the tuberculin is injected between the layers of the
skin, only a few drops being used, and it is usually applied in the region
at the base of the tail, where the skin is soft and nearly hairless. The
intradermic test is satisfactory also for the diagnosis of tuberculosis in
swine and, when so used, the tuberculin is applied into the skin of the ear
near its base.

The reaction from the intradermic test consists of a swelling at the point
of injection and is observed from 72 to 150 hours after the injection. The
character of the swelling varies, and a proper diagnosis of tuberculosis by
this test can be made only by an experienced person.

THE OPHTHALMIC TEST (INTO THE EYE).

Still another method, known as the ophthalmic test, is used quite
frequently and has been found to be of considerable value in what is known
as "check" testing; that is, it is used in connection with either of the
previously described methods. Sometimes a tuberculous animal that fails to
react to those tests shows evidence of the disease upon the application of
the ophthalmic test. The ophthalmic tuberculin is placed in one eye and the
other eye is used as a check. A reaction is indicated by a characteristic
discharge from the eye receiving the treatment, which may occur in from 3
to 10 hours after the applicat