THE BEGINNINGS OF LIFE. 2i 



Diminution of pressure seems, however, to be a very 

 potential cause of change in some fluids. The extent 

 to which changes of a fermentative character can pro- 

 gress in the absence of atmospheric oxygen, is also 

 evidently subject to much variation, in accordance 

 with the nature of the dissolved fermentable sub- 

 stances. 



Thus, in accordance with the doctrines of Baron 

 Liebig, my experiments^ as well as those of many other 

 investigators, tend to show that fermentative and 

 putrefactive changes are merely processes of chemical 

 rearrangement, which frequently take place — as it 

 were 'spontaneously' — owing to the inherent insta- 

 bility of certain nitrogenous compounds in the presence 

 of free oxygen. My experiments have, however, also 

 revealed the additional fact that, under the combined 

 influence of a moderate heat and diminished pressure, 

 some fluids will undergo fermentation even in closed 

 vessels, from which all air has been expelled. And, at 

 the same time, they compel us to believe that the 

 lowest organisms, when present, are often mere con- 

 comitant products (some of which have arisen de novo)^ 

 rather than invariable or necessary causes of the fer- 

 mentative changes. 



of ammonic tartrate and sodic phosphate. The facts recorded by Dr. 

 Sanderson (loc. cit., p. 54) as to its lack of influence over 'Pasteur's 

 solution,' is therefore quite what might have been expected. It was a 

 mistake to suppose that I considered diminution of pressure to be in- 

 variably favourable to the occurrence of fermentable changes in all fluids 

 capable of undergoing this change. 



