286 
PLEURO-PNEUMONIA IN CATTLE. 
characters as No. 4, with the exception of the thickening of 
the pleura. 
Before describing the more minute pathological appearances 
of the lungs, we deem it necessary to refer to the circum¬ 
stance that in no case had there been a natural termination, 
the animals having been slaughtered. The ultimate features 
of the disease were, therefore, not before us. In more then 
one case, however, a fatal termination could not have been far 
distant. The various conditions of the different lungs ex¬ 
amined appeared to admit of a division of the disease into 
three stages. 
Jn the first stage the lung was increased in weight and 
density. It was of a dull red or crimson hue, sometimes 
mottled with different shades. It contained air in variable 
amount—from slightly less than the normal quantity to 
almost none at all. In an advanced degree of this stage, the 
section was smooth and nearly solid. The microscopical ap¬ 
pearances were chiefly those of congestion. 
In the second stage, the affected portion of lung was per¬ 
fectly solidified and of a yellowish red colour. The natural 
cohesion was much diminished. The torn surface presented 
a granular aspect, and the smaller bronchial tubes, as well as 
the air-cells, were blocked up with solidified exudation. On 
microscopical examination the air-cells and interstitial tissue 
were found infiltrated with inflammatory corpuscles and nu¬ 
merous fatty granules and molecular matter. The elastic 
tissue, however, remained almost or quite free from change. 
In the third stage, one of two conditions was found. The 
diseased parts had either sloughed en masse , or they were 
thoroughly broken down by purulent infiltration or molecular 
necrosis. In the first of these cases nothing was seen but a 
greenish-black pulpy substance. In the latter, the bronchial 
tubes and some of their smaller ramifications still mapped 
out what had been the lung structure. 
The bronchial tubes in the latter stages of the disease were 
sometimes found to be completely filled with solidified exu¬ 
dation. In some instances tubes of the diameter of more 
than half an inch were thus blocked up. 
The pleura was not always involved in the disease. In 
some instances the deeper portions only of the lung suffered, 
the pleura being almost, if not quite, healthy. Apparently 
the first effect on that membrane was a change of colour 
generally approaching to a violet. Where the disease was 
advanced, the membrane was roughened, or was covered with 
a layer of exudation (false membrane), in one case as much 
as an inch in thickness. 
These pathological appearances enable us to identify the 
