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EXTRACTS FROM FOREIGN JOURNALS. 
Supposing that the mediastinum had been torn during the exer¬ 
cise, and that the liquid was passing from the left to the right sac 
this side was again percussed, when a notable elevation of the lint 
of dullness was detected, and an horizontal direction observed, as 
in the left side. On this, the dullness had lowered two centimetres 
more, while on the other it had risen until it had reached tht 
level of the left. 
The next day, the animal was killed, and examination revealec 
all the lesions of acute pleurisy, with a thick layer of false mem 
brane upon the lungs. The pleural effusion, of which there was 
nine liters, was of a reddish color. Examined with the microscope 
the mediastinum showed perforations resulting from the tearing 
of the mediastinum jnst as I have already described. From these 
facts I believe I am authorized to adopt the following conclusion 
1st, The posterior mediastinum of the horse is a membrane 
absolutely unperforated, in some cases, during life and after death 
2d, This membrane is generally very delicate, and conse 
quently exposed to be torn, both during life and after death, un 
der the influence of the slightest cause. 
3d, Perforations have the character of recent endothelial lac 
erations, and not that of natural foramina, analagous to those o 
the great omentum. 
4tli, The openings found post mortem, as evidence of the nor 
mal condition, are probably only partial lacerations, produce! 
accidentally through the manipulation of dissection. 
5th, There may exist in horses, unilateral pleuritic inflamma 
tory exudation, temporary , when the septum is delicate; perma 
nent when it is resisting. 
6th, At the onset, pleurisy must be very difficult, if not impos 
sible to detect by percussion, for the reason that it is probabh 
always, then, unilateral, and that the effusion cannot be detects 
until the collection has passed the line of inferior dullness of tb 
chest. 
7th, If the normal fragility of the mediastinum explains tb 
ordinary duality of pleurisy in horses, it does not disprove it 
unity in the beginning of the disease.— Bull. Mem. Soc. Cent, d 
Med. Vet. 
