352 
Pleuro- Pneumonia omonr/st Cattle. 
that instance it exhibited but sligrht traces of disease. I have, 
however, had opportunities of examining numerous animals which 
had been slaughtered during the first stage of the disonler. In - 
several, the lining membrane of the bronchial tubes presented in 
many places patches of a reddish or brownish colour, without 
any apparent thickening ; but what appeared to us remarkable, 
was a firm, whitish substance, resembling coagulated blood de- 
prived of its colouring matter, which occupied several of the 
smaller bronchial tubes, to which they were perfectly moulded. 
The pulmonary tissue was quite healthy. We may also add that 
we have met with similar appearances in lungs still further ad- 
vanced in the disease. 
I shall next bring forward some general considerations on 
the morbid appearances described in the foregoing cases. 
The inflammation of the pleura leads to an exudation of fluid, 
one part of which settles to the lower part of the chest, in a 
liquid form, more or less sanguinolent and ropy; another adheres 
to the side of the pleura, and forms layers, to which the term 
coagulable lymph is applied — in some instances those exudations 
lead to adhesions between contiguous pleurae. 
The effusion of fluid in the cavity of the chest must interfere 
with the conditions of the lung, especially if the latter be in a 
healthy state, in that case it will become compressed; but if the 
lung be inflamed, then the degree of firmness, as well as volume 
which it acquires, enables it to resist the pressure of the fluid, 
so that the presence of the latter in large quantities must then 
lead to the dilatation of the sides of the chest. The cases described 
- justify the supposition that the pleura is liable to be affected 
earlier than the lung. Thus, in the third case, the pleura of the 
posterior lobe was opaque and thickened as far as its base, whilst 
the corresponding parenchyma of the lung exhibited few, if any, 
signs of disease; a similar state existed on the opposite side, in 
which the pleura and lungs were both diseased at the spinal edge 
of the middle lobe, whilst at its free edge the pleura only was 
affected. 
The tendency on the part of the pleura to be first affected is 
not without practical importance. Commencing pleurisy may 
furnish the first untoward symptoms, and indicate the propriety 
of active treatment, to which the disease will at that period in all 
probability be amenable. 
The appearance which the sub-pleural cellular tissue presents 
in this disease is not without interest. It differs from the layers 
