SPECIMENS OF PLEURO-PNEUMONIA CONTAGIOSA. 
23 
noticed, but in this case only one lung was affected, and there 
were necrotic cavities in the interlobular connective tissue. The 
parenchyma was not consolidated. 
Next comes a very interesting series of cases in which were 
scattered foci of consolidation throughout the lung. On section, 
these solid areas presented typical pleuro-pneumonia cysts in the 
areas, large enough to be seen easily with the naked eye; these 
areas varied in size from two or three lobules to a single lobule; 
and from a single lobule down to foci the size of the head of a pin, 
many of which could be seen in a single lobule. These small foci 
had very mucl^ the appearance of tubercles, but on closer inspec¬ 
tion a small necrotic center was to be seen, even in the smallest, 
and on microscopic examination these centres were seen to be com¬ 
posed of a few air-cells which had undergone necrosis precisely 
like that in the larger cyst. Now there were cases of typical 
pneumonia in the same herd, and the evidence in considering them 
as pleuro-pneumonia is that in some cases a whole lung was involved, 
in others a greater portion of a lobe, in others a small group of 
lobules, together with single lobules and small foci, varying in size 
from a pea to a pin’s head in the same lobule. The same charac¬ 
teristics were presented in all of them, even to the smallest. 
In conclusion, I wish to call your attention to a few specimens 
which I think are very interesting and instructive. Incase No. 1 
we have acute pleuro-pneumonia contagiosa of one lung, and in 
addition to this, an exudation and new growth of tissue surround¬ 
ing the base of the trachea, and extending back through the super¬ 
ior mediastinum, involving the lymphatic glands, the oesophagus 
and the posterior aorta. This exudation looks precisely like that 
in the lung, and the lymphatic glands present many minute foci of 
necrosis. Case No. 2 presents the same changes around the tra¬ 
chea, but in this instance extends upwards so that it could be seen 
half way up the neck. It also extends downward by the large 
bronchi into the substance of the lungs, where there is chronic 
pleuro-pneumonia involving a considerable area in one lung. Case 
No. 3 shows exudation and new growth of tissue in the superior 
mediastinum, extending to the posterior border of the lung and in¬ 
volving all the organs in this region. The character of these 
changes shows the process to have been of some standing, while the 
