HYDROTHORAX. 115 



secretion from the membrane has been increased, and a 

 fluid -of a various character has been rapidly effused 

 into the chest : it has been pressing upon the lungs ; 

 it has prevented their expansion. As the cavity has 

 filled, a greater portion of the lungs has been com- 

 pressed ; and the animal has experienced the horrors 

 of lingering suffocation. 



The chest of the horse which has perished of pleu- 

 risy may, on one side, or perhaps upon both sides, be 

 filled with a serous fluid, — pale or yellow, or bloody : 

 flakes of coagulated lymph may be floating in it ; or 

 these may have been only deposited over the pleura, 

 thickening and discolouring the membrane. The 

 pleura in a horse which has died of pleurisy generally 

 peels easily off; but at other times it will closely 

 adhere to the ribs ; while bands of lymph may be 

 thrown across ; connecting the pleura upon the lungs 

 with that on the sides of the chest. The lungs are 

 not gorged and black with congestion : but they are 

 of a dingy leaden-purple colour ; often so collapsed 

 as to appear not more than one-fourth of their natural 

 size. 



In other fatal cases of pleurisy, no water will be 

 discovered in the chest ; but the membrane lining it 

 will be found thickened, opaque, red, and, in rare 

 instances, almost gangrenous in patches. 



HYDROTHORAX. 



It is of great consequence to detect the commence- 

 ment of effusion, in order that measures may be taken 

 which will give a chance of arresting its progress. 

 The first symptom, and one that can scarcely be over- 



