EMPHYSEMA OF THE LUNG. 119 



That respiratory expansion and contraction of the lungs are embar- 

 rassed in emphysematous persons, has been maintained by most authors, 

 and they, moi cover, have connected the fact with the loss of elasticity 

 of the pulmonary tissue; but, on the one hand, they have not suf- 

 ficiently understood that the loss of the elasticity of the lung is due to 

 certain changes in its structure, that it is dependent simply upon attenu- 

 ation of the parenchyma, and loss of the elastic elements of the tissue ; 

 on the other hand, they have circulated many inaccurate and false 

 notions as to the mode in which the respiratory motions are affected by 

 decreased elasticity of the lung, so that it behooves us to study this 

 influence more closely. It need hardly be mentioned that the inspira- 

 tory enlargement of the thorax, by which alone expansion of the lung is 

 effected, cannot possibly be impeded by the diminished elasticity of the 

 lungs. The inspiratory muscles, among other obstacles, have to over- 

 come this pulmonary elasticity. Hence, should this be diminished, in- 

 spiration cannot be embarrassed thereby ; on the contrary, it should 

 now proceed with greater ease than under normal conditions. It is 

 much harder to decide the question whether, how, and how much 

 decreased resiliency of the lung can interfere with expiratory contrac- 

 tion of the thorax. In the first place, when we look at the thorax 

 proper, it seems unlikely that the ribs and the sternum need the suction 

 of the elastic lung in order to return from their inspiratory to their ex- 

 piratory state. The weight of the chest-walls and the spring of the 

 ribs, which is overcome during inspiration by muscular action, seem to 

 be quite enough to neutralize the inspiratory expansion of the thorax, 

 when this muscular action is suspended. Experiments, which I have 

 caused to be made upon the bodies of adults, have at least shown that, 

 after perforation of the intercostal spaces, and after entrance of air into 

 the pleural cavity, the thorax does not enlarge.* 



There could not fail to be such an expansion, if the traction of the 

 elastic lung contributed to the establishment of the position of expira- 

 tion ; since, in these procedures, the suction, which it produces upon the 

 inner wall of the thorax, is suspended upon the entrance of air into the 

 pleural cavity, and the collapse of the lung. Hence, as, in spite of em- 

 physema, and in spite of the decreased elasticity of the lung, the thorax 

 is still able to return to its expiratory state, as it needs no aid from the 

 lungs to accomplish this, an emphysematous lung cannot afford any re- 

 sistance to the contraction of the chest. It is very remarkable that we 

 see mention made, in most pathologies, of a pressure made by emphysem- 

 atous lungs against their neighboring parts, particularly of a displace- 



* In children this may be otherwise. From the greater flexibility of their thorax, 

 it is not improbable that it is drawn inward during expiration by the draught of the 

 elastic lung, an<' is contracted more by this means than by the spring of the ribs. 



