VETERINARY SCHOOL AT ALFORT. 
G91 
ing the last session exhibited the slightest dread of water; and, 
after their death, no constant lesion could be discovered, although 
they were examined with a great deal of care. 
Veterinary surgeons of deserved eminence have said, and 
medical men have generally thought, that Paracentesis Tho- 
racis, in cases of hydrothorax, is an operation generally fatal. 
M. R. has practised it this year on five horses abandoned on 
account of dropsy in the chest. One of them was near the point 
of suffocation before the puncture was made. He lived nineteen 
days afterwards, and underwent the operation four times in this 
interval. At each time from six to seven and a half pints of 
fluid were withdrawn ; and, on the following day, there always 
seemed to be nearly as much fluid in the chest as on the pre- 
ceding one. One of them lived only nine days after the 
first puncture. He was operated on three times with intervals of 
two days between each puncture. All these animals died of 
acute pleurisy, inevitably occasioned by the new irritation pro- 
duced in the pleura, already the subject of chronic disease, 
whether by the air, which cannot always be prevented from 
entering the chest, or by the puncture or rupture of the pleural 
membrane by the instrument. 
It is said, or at least veterinarians know 7 , that pleurisy in 
the horse, unless it is the result of some traumatic lesion, is not 
confined to one side of the chest alone. Both pleural sacs are 
always inflamed, whether the inflammation is developed simul- 
taneously in both, or whether it is propagated by continuity of 
tissue from one sac to the other. It is also known that, in most 
horses, there exist in the posterior mediastinum certain openings, 
whether natural or accidental, by means of which, in case of 
effusion in the chest, the fluid passes from one sac to the 
other. It is on account of these openings that we so rarely have 
simple hydrothorax in the horse. Nevertheless, this mode of 
communication does not exist in every case of pleurisy, or, at 
least, the passage is occasionally obstructed towards the latter 
periods of the disease. We observed this in three horses that 
died in our hospital during the last year. Soft and thick false 
membranes obstructed these openings, and cut off all communi- 
cation between the two sacs. In one of these cases there was 
considerable effusion in both sacs, but the liquid stood higher 
in one than in the other. M. Delafond has spoken of these pecu- 
liarities. 
Two casesof partial and suppurating pleurisy occur- 
red from the opening of pulmonary vomicae into the pleural sac. 
In both cases, adhesion between the costal and pulmonary pleurm 
circumscribed very much the portion of serous membrane which 
