posed in this manner.

The first sound of the heart occurs while the heart muscle is
contracting and while the blood is being forced from the heart and the
valves are rendered taut to prevent the return of the blood from the
lower to the upper chambers. The second sound follows quickly after the
first and occurs during rebound of blood in the arteries, causing
pressure in the aorta and tensions of the valves guarding its opening
into the left ventricle. The first sound is of a high pitch and is
longer and more distinct than the second. Under the influence of disease
these sounds may be altered in various ways. It is not profitable, in a
work such as this, to describe the details of these alterations. Those
who are interested will find this subject fully discussed in the
veterinary textbooks.

TEMPERATURE.

The temperature of the horse is determined roughly by placing the
fingers in the mouth or between the thighs or by allowing the horse to
exhale against the cheek or back of the hand. In accurate examination,
however, these means of determining temperature are not relied upon, but
recourse is had to the use of the thermometer. The thermometer used for
taking the temperature of a horse is a self-registering clinical
thermometer, similar to that used by physicians, but larger, being from
5 to 6 inches long. The temperature of the animal is measured in the
rectum.

The normal temperature of the horse varies somewhat under different
conditions. It is higher in the young animal than in the old, and is
higher in hot weather than in cold. The weather and exercise decidedly
influence the temperature physiologically. The normal temperature varies
from 99.5 deg. to 101 deg. F. If the temperature rises to 102.5 deg. the horse is
said to have a low fever; if the temperature reaches 104 deg. the fever is
moderate; if it reaches 106 deg. it is high, and above this point it is
regarded as very high. In some diseases, such as tetanus or sunstroke,
the temperature goes as high as 108 deg. or 110 deg.. In the ordinary infectious
diseases it does not often exceed 106 deg.. A temperature of 107.5 deg. and
above is very dangerous and must be reduced promptly if the horse is to
be saved.

THE ORGANS OF RESPIRATION.

In examining this system of organs and their functions it is customary
to begin by noting the frequency of the respiratory movements. This
point can be determined by observing the motions of the nostrils or of
the fl