SECRETARY'S REPORT. 49 



disease, the latter may terminate in from seven to fourteen days, 

 rarely under, more frequently over that time. Death is, unfor- 

 tunately, the most common termination. A complete recovery 

 may however take place, and the animal afterwards die of the 

 effusion into the pleura and pericardium, or chronic pulmonary 

 oedema. Sometimes, but rarely, complete recovery takes place ; 

 but this is only possible when the disease is checked at the 

 commencement, or at an early period. 



MORBID ANATOMY. 



The same author states that the morbid appearances vary ac- 

 cording to the period at which the animal dies or is killed. 



At the commencement, no exudation is found, but isolated 

 portions of the interlobular cellular tissue are in a hyperoemic 

 condition, somewhat swollen and opaque. If the process has 

 advanced a little farther, we find in the same interlobular tissue 

 a thin layer of amorphous material, and, not infrequently, 

 small ecchymoses. The pulmonary tissue is oedematous, and 

 contains less air than usual. These appearances at the com- 

 mencement are usually noticed in the interior of the lung, 

 without disease of the pleura. If, however, superficial portions 

 of tissue are effected, the pleura participates, becomes opaque, 

 and, still later, is covered with an exudation which is also found 

 beneath it. In very rare cases, this change takes place not only 

 in the interlobular tissue, or in this and the pleura, but also in 

 the pulmonary tissue itself, i. e., the vesicular structure, which, 

 as we have seen, is ordinarily the seat of oedema only. In 

 many cases, large portions of the cellular tissue are attacked, 

 and sometimes the process commences upon the surface and in 

 the deeper seated parts of the lung at the same time. The 

 disease either commences in one lung and is limited to it, or 

 extends to the other, or invades both luiigs at the same time, 

 which is, however, more rare. At a still later period the cut 

 surface presents a marbled appearance, and the pleura is covered 

 with a layer of false membrane, the thickness of which varies 

 in different cases. In the pleural cavity or in the interstices of 

 the fibrinous exudation is found more or less serum. 



Still later, the lungs are found enlarged, and their weight much 

 increased. They are firm, compact, liver-like, and there is an 

 absence of crepitation. The surface is not uniform, but divided 



