ON THE NATURE OF FERMENTATION. ISS 



been proved to have the power of self-multiplication. At the 

 same time, gentlemen, it may be admitted that the thing might 

 be theoretically possible. It is conceivable, for instance, that a 

 resolvent, if we may so speak, of comparatively simple constitu- 

 tion might, by its action upon a resolvable compound, resolve it 

 into substances, one of which should itself be the resolvent, and, 

 if that were so, the process might go on ad infinitum. That is 

 conceivable ; and although we have no instance of the kind on 

 record, yet we have persons in high authority, as teachers both 

 of physiology and of pathology, maintaining the view that 

 putrefactive fermentation, for instance, in the bacteria are pro- 

 bably mere accidental concomitants ; that the real essential agent 

 in the putrefaction is not an organism at all, but some so-called 

 chemical ferment destitute of life. And so long as we have 

 authorities maintaining such a view, it is necessary to test its 

 truth or falsehood by searching inquiry; and such has been 

 the object with which my investigations of the last two months 

 have been conducted. 



As regards the putrefactive fermentation, we have already evi- 

 dence in the flask and in the glass that I have shown you (the 

 flask also has no putrefactive odour emanating from it), that blood 

 has in itself no mherent tendency to putrefy. It must receive 

 something from without, and that something is not mere oxygen 

 or any other atmospheric gas. I have now to point out to you 

 that the addition of water is not of itself sufficient to induce 

 this fermentation. Blood and water constitute a mixture 

 highly putrescible, very much more so than blood itself. But 

 in this flask we have had mixed with water the contents 

 of one of the liqueur glasses of unputrefied blood like that 

 before shown to you. The water, however, had been previously 

 boiled, so as to kill any organisms in it ; boiled and cooled under 

 the protection of a cotton cap, and then, the cotton cap being 

 raised, careful provisions (into which I must not enter) against 

 the entrance of dust being taken, the clot was spooned into the 

 water ; a fresh cotton cap, perfectly pure, was put on, and so 

 we got, I believe for the first time, a permanent cold watery ex- 

 tract of blood, and here it retains the same brilliant clearness 

 that it had in the first instance, more than a month ago. Mere 

 water, therefore, is as inadequate to induce the putrefactive fer- 

 mentation of blood as are the gases of the air. 



But the fermentation which I have been especially investigat- 

 ing has not been the putrefactive, but one which seemed to me 

 more convenient for the purpose, the lactic fermentation, by 

 means of which milk sours and curdles, through conversion of 

 the sugar of milk into lactic acid. This is a curious instance of 

 a chemical transformation. The composition, as regards the pro- 



