THE ORGANS OF RESPIRATION. 15l 



effusion without any very marked constitutional dis- 

 turbance, and without fever, tlie peculiar deformity 

 of the chest, and the great displacement of the heart 

 or of the liver, may induce a suspicion of the real 

 affection. The total absence of the respiratory mur- 

 mur, accompanied by dulness upon percussion, wiU 

 also aid in the diagnosis, which may be confirmed, in 

 the majority of cases, by an exploratory puncture. 

 This operation is not attended with much risk, as the 

 adhesions between the two folds of the pleura usually 

 obliterate its cavity. 



In those cases in which hydatids or echinococci 

 are expectorated, the diagnosis is generally easy, as 

 it is only necessary to ascertain the nature of the 

 expectorated matter. A careful examination into 

 the facts connected with the individual case will 

 decide whether the entozoa are situated in the lungs 

 or in the liver. 



Hydatid cysts which have been developed in any 

 of the abdominal viscera, and especially in the upper 

 portion of the liver, may force up the diaphragm, 

 press upon the lungs, and thus produce an impedi- 

 ment to their free expansion. Like the hydatids 

 which have been developed within the thoracic cavity 

 itself, they may perforate, and discharge their con- 

 tents into, the pleura or the pericardium, or they 

 may establish a communication with one of the 

 bronchi, and empty themselves externally through 

 this passage. The symptoms, progress, and termi- 

 nation of these cases present a considerable analogy 

 to those of hydatid cysts which are primarily situated 

 within the chest. 



The hydatids which are developed near the upper 



