PUTREFACTION AND FERMENTATION 479 



But to return to the course before us. There are some details regarding 

 the mode in which you may attend it to the greatest advantage, which I shall 

 reserve till we next meet. And now, as the place where we are assembled 

 forbids my entering at once upon demonstrative surgery, I propose to devote 

 the remainder of this hour to the endeavour to convince you, so far as the 

 limited time at our disposal permits, of the truth of the germ theor}- of 

 putrefaction, the basis of a new mode of treatment which finds its application 

 in all departments of practice ; so that without understanding it we cannot 

 advance satisfactorily in the consideration of individual cases. I allude to 

 the antiseptic system. This system of treatment consists of such manage- 

 ment of a surgical case as shall effectually prevent the occurrence of putre- 

 faction in the part concerned. When this is really secured, surgery becomes 

 something totally different from what it used to be ; and injuries and diseases 

 formerly regarded as most formidable, or even hopeless, advance quieth' and 

 surely towards recovery. Of this system the germ theory of putrefaction is 

 the pole-star which will guide you safely through what would otherwise be 

 a navigation of hopeless difficulty. 



The germ theory declares that the putrefaction of organic substances 

 under atmospheric influence is not effected, as used to be supposed, by the 

 oxygen of the air, but by living organisms developed from germs floating in 

 the atmosphere as constituents of its dust. 



The first great step towards the establishment of this theory- was the 

 discovery of the yeast plant in 1838 by Cagniard-Latour, who, having detected 

 in yeast a microscopic fungus, the Tonila Cerevisiae, which appeared to be the 

 essential constituent of the ferment, attributed the resolution of sugar into 

 alcohol and carbonic acid to the disturbing influence of the growing organism.^ 

 In the following year, Schwann of Berlin published the results of a remark- 

 able investigation into the cause of putrefaction (in the course of which, by 

 a coincidence such as is not uncommon in the history of science, he, too, had 

 independently discovered the j^east plant), and he related experiments which 

 showed that a decoction of meat might remain for weeks together free alike 

 from putrefaction and from the development of infusoria or fungi in a flask 

 containing air frequentty renewed, provided that the atmosphere was subjected 

 to a high temperature at some part of its course towards the containing vessel.- 

 Hence he concluded that putrefaction was caused by the growth of organisms 

 springing from germs in the air, the heat preventing the putrefactixo change 

 by depriving the germs of their vitalit}-. In other words, he propounded the 



^ Sec Comptes Rendtis, toin. i\-, p. 005. 



' See Poggendorf's Annalen, vol. xli, art. xvi. 



