PLEUEISY. 587 



3rd. Towards the end of the second week the expanded liquid 



begins to clear up. This is the indication of the beginning 



of the third period. 

 4th. The liquid is almost always clear after the 25th or 30th day, 



and this is the epoch of transition in the horse from the 



acute to the chronic state of pleurisy. 



" The change which the pulmonary tissue undergoes as a result of 

 pleurisy is specially considered by M. Saint-Cyr. In a case of con- 

 firmed pleurisy, the lung is of dull colour, diminished in size, collapsed, 

 and flabby, scarcely crepitant under pressure, specifically heavier than 

 water. Under pressure, it is tough, not friable like lung hepatized as 

 the result of inflammation. The cut surface of such pleuritic lung is dry, 

 smooth, and presents the interlobular septa unusually well marked. 

 Nevertheless the lung tissue is free from adventitious deposit, and the 

 air-cells, though flattened, are not destroyed; they admit of being 

 expanded, as in the healthy condition, by artificial respiration. Only 

 in one case, a dog affected with pleurisy for more than two months, has 

 the author been unable to re-expand the collapsed lung. The causation 

 of this collapsed state is complex : pressure of the effused liquid, insuf- 

 ficient expansion of the chest, deposition of false membranes, and our 

 author even supposes sympathetic contraction of the visceral muscular 

 fibres." 



Treatment. I have no great faith in blood-letting in 

 cases of pleurisy, and rely more on purgatives, injections, 

 and mustard poultices, or more active blisters. This is to 

 be followed up by the administration of diuretics, such as the 

 draught here prescribed : 



% Pot. nitr. . . . . . ss. 



Camphorse 3ij. 



Sp. eth. nitr gij. 



Aqu?e Jxx. 



Mix. Draught to be repeated every six hours. 



I have used digitalis in considerable doses when the first 

 symptoms of hydrothorax have appeared, giving a half-drachm 



