300 OPERATION OF THE 



getting from the thorax into the cellular membrane ? And is 

 not this conjecture strengthened by observing that in Mr. 

 Cheston's case the air, on the fourth day, no longer got into 

 the cellular membrane, and that soon after the patient died? 



It has been observed that in gunshot wounds, where the 

 ball has passed through the lungs, and in other large penetrat- 

 ing wounds of the chest, the patient has breathed most easily 

 when the external wound has been covered, and has hardly 

 been able to breathe when it was opened. In these circum- 

 stances the difficulty of breathing seems to be owing to the air 

 getting into the cavity of the thorax in inspiration, instead of 

 entering the lungs by the trachea, so that the lungs are not 

 distended by the expansion of the chest; and the patient, 

 whilst such a wound is uncovered, is deprived of the use of the 

 lobes of that side, either partially or entirely, according as the 

 wound of the thorax bears a less or greater proportion to the 

 branch of the trachea of that side in which the wound is. 

 Moreover, as the difficulty of breathing in these cases is not 

 considerable whilst the external wound is covered, is it not 

 probable that the divided air -vesicles in most of these deep 

 wounds are closed, either by blood coagulated in the wound, 

 or extravasated into the neighbouring cells, by which means 

 the air is not transmitted through them as through the super- 

 ficial abrasions ? this seems probable from what was observed 

 in Experiments i and u. 



The case of the person, whose body I opened, likewise shows 

 that the lungs may be lacerated, and air let loose, without any 

 wound penetrating the cavity of the thorax; for in that in- 

 stance the laceration was at a distance from the ribs, and was 

 produced by the violence of the concussion only. It therefore 

 intimates the necessity of the operation even in some cases 

 where there is no emphysema, though it must be acknowledged 

 it will not be easy to distinguish them. 



As vomicae and ulcerations of the surface of the lungs are 

 attended with erosion and destruction of the air-vesicles, it 

 may at first sight seem probable that they may also be at- 

 tended with a discharge of air into the cavity of the thorax ; 

 but the probability will be much lessened when we consider, 

 that the inflammation which precedes the formation of pus is 

 likely to do here what it does in the cellular membrane ; that 



