EQUINE CONTAGIOUS PLEURO-PNEUMONIA 451 
ish, gelatinous fluid. The interlobular connective tissue is infil- 
trated with serum. 
“On the fourth or fifth day, not before, bacteria begin to colonize 
in the diseased parts of the lungs, in the form of cocci arranged in 
chains. These cause inflammatory, often hemorrhagic, changes 
that may lead to extensive necrosis.” 
In the lobular form of pleuro-pneumonia, which it is stated fur- 
nishes the largest number of subjects for post-mortem examination, 
there are frequently hemorrhagic foci in the acute cases and possibly 
gangrenous pneumonia with secondary pleuritis. Small necrotic 
areas are scattered through the hepatized portions. Parenchymatous 
degeneration of other vital organs is reported. The hepatized foci 
are located more expecially near the base of the lungs and in the lower 
(ventral) portions. They vary in size from a millimeter to 20 or 
more centimeters in diameter. In recent lesions, these areas are very 
small, of a grayish-red color and surrounded by a grayish zone con- 
sisting of leucocytes. In more advanced lesions they become yellow- 
ish, necrotic and finally cavities are formed varying from the size of a 
pea to that of ahen’segg. These cavities are surrounded by a smooth 
capsule. There are other foci which contain greasy, fetid, watery pus 
(gangrene of the lungs), by reason of the necrotic part of the lung 
undergoing liquefaction in consequence, it is stated, of the admittance 
of air. The lungs often contain suppurating foci composed of a 
whitish pus mixed with necrotic lung tissue. It sometimes happens 
that the foci just described are absent in the lungs, although during 
life suggestive symptoms of such a localized affection may have been 
present. In these cases, it is assumed that absorption of the necrotic 
tissue has taken place. The remaining tissue of the lungs is more or 
less hyperemic or edematous. 
The pleurse show signs of a diffuse, exudative inflammation, the 
starting point of which in the large majority of cases is from necrotic 
deposits which are situated in the periphery of the lungs. Pleuritis 
may occur, however, apparently as a primary lesion. The contents 
of a necrotic deposit in the lungs rarely discharge into the pleural 
cavity. In some cases, the visceral and costal layers of the pleurz 
are congested, diffusely or in spots, and are sprinkled with hemor- 
rhages. Frequently the pleure are covered with soft red granulations 
over which are layers of yellowish exudate which are partly mem- 
branous and partly coagulated in a reticular manner, and which can 
usually be easily removed. The exudate may be less firm and more 
