herefore, is not complete; it is only apparent and partial.

To those accustomed to examining the lungs of cattle, other and extremely
important symptoms may be apparent during the course of the disease. By
applying the ear over the walls of the chest an area of a certain extent
may be found in which the natural breathing sound is diminished or entirely
lost. This represents the diseased portion of the lungs. In other cases a
loud blowing sound may be heard, quite different from any sound produced
when the lung is in a healthy condition. In some cases crepitation is heard
near the border line of the diseased area and friction sounds produced by
the roughened pleura; these can be appreciated, however, only by those
whose ears have been trained to distinguish between the different sounds
which reach the ear when applied to the chest wall. By percussion--that is,
by pressing the fingers of the left hand firmly against the wall of the
chest and tapping upon the middle finger with the ends of the fingers of
the right hand--an area of dullness may be discovered corresponding to the
portion from which the respiratory murmur has disappeared. This loss of
respiration detected by auscultation, and the dullness brought out by
percussion, are the most important evidences of an inflamed or consolidated
lung.

Seriously affected animals remain standing if they have sufficient
strength, but those which lie down always lie on the affected side.

The proportion of animals which become affected after being exposed varies
according to the virulence of the outbreak, the susceptibility of the
animals, and the length of time during which exposure is continued.
Sometimes not more than 15, 20, or 30 per cent will contract the disease
when a large herd is exposed; on the other hand, however, 80 or 90 per cent
may be affected. The proportion of cases in which the disease proves fatal
also varies greatly--it may not exceed 10 and it may reach 50 per cent. In
general, it may be said that about 40 per cent of the exposed animals will
contract the disease and about one-half of these cases will prove fatal.

_Post-mortem appearances._--Owing to the complexity of the structure of the
lung tissue, its ramifications of bronchial tubes and blood vessels, and
its abundant supply of lymphatics, the pathological changes in
pleuropneumonia are interpreted with great difficulty. Furthermore, there
are certain kinds of pneumonia which present some resemblance