PROGRESS OF THE GERM THEORY OF DISEASE. 463 



tical applications, was still empirical knowledge. That dirt was fatal 

 they had discovered ; but why it was fatal few of them knew. At 

 this point Lister came forward with a scientific principle which ren- 

 dered all plain. Dirt was fatal, not as dirt, but because it contained 

 living germs which, as Schwann was the first to prove, are the cause 

 of putrefaction. Lister extended the generalization of Schwann from 

 dead matter to living matter, and by this apparently simple step revo- 

 lutionized the art of surgery. He changed it, in fact, from an art into 

 a science. 



" Listerism " is sometimes spoken of as if it merely consisted in the 

 application of carbolic-acid spray ; but no man of any breadth of 

 vision will regard the subject thus. The antiseptic system had been 

 enunciated, expounded, and illustrated, prior to the introduction of 

 the spray. The spray is a mere offshoot of the system elegant and 

 effective it is true, but still a matter of detail. In company with my 

 excellent friend Mr. John Simon, I once visited St. Bartholomew's 

 Hospital, and became acquainted, in its wards, with the practice of the 

 late Mr. Callender. The antiseptic system was there as stringently 

 applied as at King's College. Immediately before his departure to 

 America I spoke to Mr. Callender on this subject ; and he then told 

 me expressly that his aim and hope had been, not to introduce a new 

 principle, but to simplify the methods of Lister. And yet Mr. Cal- 

 ender's practice is sometimes spoken of as if it were, in principle, dif- 

 ferent from that of his eminent contemporary. 



It is interesting, and indeed pathetic, to observe how long a dis- 

 covery of priceless value to humanity may be hidden away, or rather 

 lie openly revealed, before the final and apparently obvious step is 

 taken toward its practical application. In 1837 Schwann clearly es- 

 tablished the connection between putrefaction and microscopic life ; 

 but thirty years had to elapse before Lister extended to wounds the 

 researches of Schwann on dead flesh and animal infusions. Prior to 

 Lister the possibility of some such extension had occurred to other 

 minds. Penetrative men had seen that the germs which produce the 

 putrefaction of meat might also act with fatal effect in the wards of a 

 hospital. 



Thus, for example, in a paper read before the British Medical As- 

 sociation at Cambridge in 1864, Mr. Spencer Wells pointed out that 

 the experiments of Pasteur, then recent, had " all a very important 

 bearing, upon the development of purulent infection and the whole 

 class of diseases most fatal in hospitals and other overcrowded places." 

 Mr. Wells did not, as far as I know, introduce any systematic mode of 

 combating the organisms whose power he so early recognized. But, I 

 believe, in hardly any other department of surgery has the success of 

 the antiseptic system been more conspicuous and complete than in that 

 particular sphere of ^practice in which Mr. Wells has won so great a 

 name. 



