26 THE FLOATING-MATTER OF THE AIR. 



wards where death was rampant from pyaemia, erysipe- 

 las, and hospital gangrene, he was able to keep his 

 patients absolutely free from these terrible scourges. 

 Let me here recommend to your attention Professor 

 Lister's ' Introductory Lecture before the University of 

 Edinburgh,' which I have already quoted ; his paper on 

 * The Effect of the Antiseptic System of Treatment on 

 the Salubrity of a Surgical Hospital ; ' and the article 

 in the ' British Medical Journal ' of January 14, 1871. 

 If, instead of using carbolic acid spray, he could 

 surround his wounds with properly filtered air, the re- 

 sult would, he contends, be the same. In a room, where 

 the germs not only float but cling to clothes and walls, 

 this would be difficult, if not impossible. But surgery 

 is acquainted with a class of wounds in which the blood 

 is freely mixed with air that has passed through the 

 lungs, and it is a most remarkable fact that such air 

 does not produce putrefaction. Professor Lister, as far 

 as I know, was the first to give a philosophical interpre- 

 tation of this fact, which he describes and comments 

 upon thus : 



I have explained to my own mind the remarkable fact 

 that in simple fracture of the ribs, if the lung be punctured 

 by a fragment, the blood effused into the pleural cavity, 

 though freely mixed with air, undergoes no decomposition. 

 The air is sometimes pumped into the pleural cavity in such 

 abundance that, making its way through the wound in the 

 pleura costalis, it inflates the cellular tissue of the whole 

 body. Yet this occasions no alarm to the surgeon (although 

 if the blood in the pleura were to putrefy, it would infallibly 

 occasion dangerous suppurative pleurisy). Why air intro- 

 duced into the pleural cavity through a wounded lung, should 

 have such wholly different efiects from that entering directly 

 through a wound in the chest, was to me a complete mystery 

 until I heard of the germ theory of putrefaction, when it at 

 once occurred to me that it was only natural that air should 



