obed
and searched to the bottom for the presence of a foreign substance or the
evidence of decaying cartilage. When the probe touches necrosed cartilage
it will feel like a piece of dry leather or partially softened wood. A
counter opening must then be made at this place, and all diseased cartilage
cut away with the knife. The subsequent treatment consists in keeping the
artificial wound open for the discharge of pus, and the injection of
chlorid of zinc, 5 grains to the ounce of water, once or twice a day, until
the wound is healed.

ENCHONDROMA OF THE EAR.

This is an excessive growth of cartilage, found at the base of the ear in
the form of a hard, painless tumor, firmly attached to the movable ear. The
only recourse for its removal is the knife in the hands of one acquainted
with the anatomy of the part involved in the operation.

INFECTIOUS DISEASES OF CATTLE.

Revised by JOHN R. MOHLER, A. M., V. M. D.,

_Chief, Bureau of Animal Industry._

GENERAL INTRODUCTION.

The importance, to the farmer and stock raiser, of a general knowledge of
the nature of infectious diseases need not be insisted on, as it must be
evident to all who have charge of farm animals. The growing facilities for
intercourse between one section of a country and another, and between
different countries, cause a wide distribution of the infectious diseases
once restricted to a definite locality. Not only the animals themselves,
but the cars, vessels, or other conveyances in which they are carried may
become agents for the dissemination of disease. The growing tendency of
specialization in agriculture, which leads to the maintenance of large
herds of cattle, sheep, and hogs, makes infectious diseases more common and
more dangerous. Fresh animals are being continually introduced which may be
the carriers of disease from other herds, and when disease is once brought
into a large herd the losses become very high, because it is difficult, if
not impossible, to check it after it has once obtained a foothold.

These considerations make it plain that only by the most careful
supervision by intelligent men who understand the nature of infectious
diseases and their causes in a general way can these be kept away. We must
likewise consider how incomplete our knowledge concerning many diseases is,
and probably will be for some time to come. The suggestions and
recommendations offered by investigators, therefore, may not always be
correct, and