PARACENTESIS THOEACIS. 299 



violence of the symptoms enumerated above, such as the op- 

 pressed breathing, &C. 1 For when these symptoms are not 

 considerable, and the air gets out of the chest with sufficient 

 freedom, the operation then becomes unnecessary ; of this the 

 case in the Medical Observations is an evidence; for there the 

 inflation proceeded rapidly, and less air was retained in the 

 chest ; so that all that was necessary to be done, was to let it 

 out of the cellular membrane by scarifications, which accord- 

 ingly were successfully made. 



Perhaps it may be inquired here, how the lacerated air- 

 vesicles, which once let out the air, should ever close ? To this 

 I should answer, that probably the inflammation, subsequent to 

 the wound of the lungs, closes or unites the divided air- vesicles 

 and small branches of the bronchia in such a manner as to 

 prevent their transmitting air ; much in the same way as the 

 wounds made in the cellular membrane by scarifications in 

 anasarcous cases are closed, or as those made in Dr. Hunter's 

 and Mr. Cheston's cases of the emphysema seem to have 

 been. 2 And this appears more evident from observing, that 

 in Dr. Hunter's case the air appears not to have got into the 

 cellular membrane (or out of the wound of the lungs) after 

 the second day, by which time it should seem that the wound 

 of the lungs was sufficiently inflamed to produce the effect 

 above mentioned. 



Is it not likewise probable, from the same principles, that 

 the penetrating wound of the chest occasioned by the fractured 

 rib, though at first large enough, may in some cases be so 

 closed by the subsequent inflammation as to prevent the air 



1 It may not perhaps be improper to mention here, that we are not in every pene- 

 trating wound of the chest to suppose that the lungs are wounded, even though we 

 see that the air rushes in and out hy the wound. This I thought proper to observe, 

 because some, to whom this paper was communicated, objected that they had seen 

 patients in whom the air came out of the chest in expiration, so as to blow off the 

 dressings ; yet on compressing the wound, no difficulty of respiration followed. But 

 here it is probable that the lungs were not hurt, and that the air, which had been 

 thrown out by the wound of the thorax in expiration, had entered by it in inspi- 

 ration, an appearance which will be easily explained by those who are acquainted 

 with the structure and functions of the thorax. * " 



- The closing of the scarifications, in Mr. Cheston's case, prevented the air from 

 getting entirely out of the cellular membrane, and he was therefore obliged to repeat 

 that operation to empty it completely. 



