128 DISEASES OF THE PARENCHYMA OF THE LUNG. 



This circumstance, which we had attributed to the collateral oedema 

 of the healthy portion of the lung, which is usual hi emphysema, is 

 ascribed by Seitz^ of Giessen, in some degree, to the descent of the 

 secretion by gravitation from the upper to the lower regions of the lung 

 (a theory which has much to recommend it). The murmurs sometimes 

 audible in the heart, even where there is no valvular disease, are to be 

 considered in treating of degeneration of the heart ; but I may say that 

 I fully corroborate the observation of Seitz, that the heart-sounds, though 

 remarkably feeble at the level of the third and fourth ribs, where the 

 organ is covered by the lungs, are very audible at the epigastrium. The 

 explanation is manifest. 



The disease may commence in childhood, and continue throughout 

 life. Many emphysematous persons reach even an advanced age, al- 

 though their troubles grow with their years, the dyspnoea augmenting, 

 the asthmatic attacks increasing in violence and frequency. The suf- 

 ferers are never cured. If they feel better in summer, this is because 

 of the remission of the accompanying catarrh, and the decrease of the 

 dyspnoea, as far as it depends upon these complications. The part which 

 chronic catarrh plays, not only in the dyspnoea, but in the cyanosis and 

 dropsy of the emphysematous, is, as we have repeatedly explained, a 

 very considerable one. Death finally takes place (if the patients do not 

 meanwhile succumb to an intercurrent malady), with the symptoms of 

 marasmus or of general dropsy. The patients very rarely die of an 

 asthmatic attack. 



DIAGNOSIS. Emphysema of small extent cannot be diagnosticated 

 with certainty. Cases of considerable severity, which lead to violent 

 dyspnoea and cyanosis, are easily to be distinguished, by physical ex- 

 amination, from other conditions which give rise to those symptoms. 

 Of the distinction between pneumo-thorax and emphysema we shall 

 speak hereafter. 



For the differential diagnosis between vicarious and substantive em- 

 physema, the history of the case and the physical signs in some cases 

 at, least furnish ground. If the emphysema have developed after a 

 pneumonia or pleurisy, if no particularly violent cough have preceded 

 it, or if the patients distinctly affirm that the shortness of breath is of 

 earlier date than the cough, we may infer, with a certain degree of confi- 

 dence, that a partial wasting of the lung or adhesion of the pleura has 

 occasioned a vicarious emphysema in the anterior and lower part of the 

 lung, spared by the atrophy, or that the disease depends upon a primary 

 structural wasting. On the other hand, should we find emphysema in 

 a person who has been a musician or postilion, who boasts of having 

 played well, and of having been able to keep up the note for a long 

 while, or if the shortness of breath have arisen after whooping-cough, 



