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could have been safely affirmed was, that by boiling 

 the fluid, and then protecting it from subsequent con- 

 tact with everything that could act as a ferment, 

 fermentation would not take place. 



Even this however, as the preceding experiments 

 fully show cannot be truly affirmed to be a general 

 rule. Some infusions do undergo change, notwith- 

 standing this treatment and deprivation, whilst others 

 do not : that is to say, some still preserve a first 

 degree of fermentability even after boiling, whilst 

 others are reduced by this process to the second 

 degree of fermentability. These latter are unable to 

 initiate changes by virtue of their own inherent insta- 

 bility ; molecular re-arrangements require to be set 

 on foot in them by contact with some more unstable 

 substance, which is itself undergoing change. 



That such is the correct explanation of the reason 

 why some fluids do not ferment in bent-neck flasks, 

 seems obvious from the discordant results obtained 

 in many other experiments, after the free admission of 

 uncalcined air to the fluids which had been boiled. 

 The fluids were deprived of their virtues in some cases 

 by the heat to which they had been subjected, so that 

 whether they underwent change or not, may have 

 depended upon the accidental presence or absence, 

 in the air which was subsequently admitted to the 

 fluid, of some unheated organic fragments, capable 

 of initiating fermentative changes. If germs were 

 as omnipresent as they have been represented to 



