EFFUSION. 137 



These prove that effusion^ both of lymph and water^ may 

 take place in a few days^ and that they are not, as was 

 formerly believed, the effect solely of chronic inflammation. 



Hamont obtained precisely the same results from a horse 

 into whose left pleural sac he injected seven ounces of a weak 

 solution of tartaric acid, and the next morning repeated 

 this injection, and then, twenty minutes afterwards, destroyed 

 him, while he was in a state of tremor and agitation 

 of breathing. Opened immediately, in the left side was 

 found some of a citrine liquid ; pleura injected and red- 

 dened; diaphragm and pericardium covered with a thin 

 layer of soft lymph; lungs pallid and collapsed. On the 

 right side the pleura was transparent without any injection 

 of its vessels. 



Delafond^s experiments, twenty-two in number, lead us 

 to' the same conclusion, although they were instituted with 

 other views, viz., for the purpose of ascertaining the 

 pathognomonic characters of pleurisy. They have shown 

 that the commencement of pleurisy is the period most 

 difficult of recognition ; that the signs furnished by efi'usion 

 were most to be depended upon ; that in the horse, on 

 account of the texture of the mediastinum, no certainty 

 could be arrived at concerning right and left pleurisies ; but 

 that, in the dog, it is still possible to maintain such distinction, 

 the mediastinum of that animal offering sufficient resistance 

 in some cases to confine the fluid within the cavity into which 

 it is effused. Even in this subject, however, such does not 

 always happen. 



The PLEURA BECOMES ALTERED IN TEXTURE in chrouic 



or relapsed cases of pleurisy. It gets thickened, indurated ; 

 grows tough, and apparently less vascular, and assumes a 

 morbidly white aspect. In other cases I have seen it 

 studded with little knots, like tubercles. 



The SEROUS MEMBRANES in the horse are exceeding apt 

 to fall into a morbid or disordered condition simultaneously; 

 rather, I should say, through some peculiar diathesis of 

 body than by sympathy; though I have no doubt there are 

 cases in which the latter has considerable influence. This 



