6o ON THE ANTISEPTIC SYSTEM 



indeed greatly marred the beauty of the fungi, having evidently scattered other 

 germs about, which remained latent till fresh air was admitted.] 



Looking at this experiment as a whole, we see that the atmosphere was 

 rendered incapable of inducing in that specimen of urine either putrefaction 

 or the formation of even the lowest and most minute known organisms, by 

 merely depriving it of its suspended particles ; or, conversely, that the ' air- 

 dust ' is the essential cause both of organic development and of putrefactive 

 changes in such a liquid ; while the experiment further illustrates what seems 

 to be a general law ; viz. that the low forms of life to which the atmospheric 

 particles give rise, so far as we are able to observe them, resemble higher plants 

 or animals in springing only from pre-existing organisms. Any one who bears 

 these facts in mind will have little difficulty in admitting the truth of the germ 

 theory of putrefaction ; and I venture to recommend to any of you who may 

 hereafter feel perplexed by the contradictory and bewildering statements of 

 various authors upon this subject, and be tempted to regard it as hopelessly 

 obscure, that he should recall to his memory the clear evidence respecting it 

 which has been brought before you this evening. 



Emphysema and Pneumothorax from Simple Fracture of the Ribs. 



This mode of experimenting, as described by Pasteur, besides charming me 

 by its simplicity and conclusiveness, had a further special interest for myself, 

 because, before knowing of it, I had explained to my own mind on the same 

 principle the remarkable fact, previously quite inexplicable, that, in simple frac- 

 ture of the ribs, if the lung be punctured by a fragment driven inwards upon it, 

 the blood effused into the pleural cavity from the wound in the highly vascular 

 organ, though freely mixed with air which enters the pleura through the same 

 orifice, undergoes no decomposition, as is clearly implied by the absence of any 

 symptoms of pleurisy in such cases. 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, unless the opening in the parietal pleura 

 become insufficient to permit free egress for the air, which then becomes pent 

 up in the serous cavity, and, distending it far beyond its natural dimensions, 

 encroaches on the other lung so seriously as to embarrass or even abolish its 

 functions. Thirteen years ago, I had the opportunity of making a post mortem 

 examination of the body of a man who had died under such circumstances ten 

 days after the receipt of the injury which caused his symptoms ; and I was 

 much struck to find the enormously distended pleura free from effusion, and 

 perfectly smooth and healthy. Why air introduced into the pleura through 



