THE BEGINNINGS OF LIFE. 349 



flection, it appeared to me to be one which might very 

 possibly be erroneous. 



Putrefactive or fermentative changes might not 

 always be initiated by contact of organic matter with 

 oxygen or any other gas, it might occasionally be de- 

 pendent upon the inherent instability of the organic 

 matter itself. Independently of the fact, therefore, 

 that the sealing of the flask after all the air had been 

 expelled and during ebullition of the fluid, was a much 

 simpler process than having to admit calcined air and 

 sealing the flask after it had cooled, it seemed likely 

 that the presence of a vacuum might, for other reasons, 

 sometimes prove to be a great advantage. It appeared 

 quite possible that the diminution of pressure in the 

 early stages of the experiment might favour the ini- 

 tiation of rearrangements amongst the molecules of the 

 dissolved organic substances, whilst the absence of air 

 might permit these changes to go much further than 

 they could have done if calcined air had been present, 

 because the vacuum would afford a space into which 

 residual gases might collect without at once inducing 

 an undue amount of pressure within the flask 1 . Ex- 



1864, p. 12, note); whilst on another page he says: 'La presence de 

 Tair parait etre 1'une des conditions fondam en tales de la fermentation. 

 Plus il est abondant plus elle semble active. Si on le confine, ou s'il 

 manque, cet acte chimique est paralys ou absolument entrave.' (p. 156.) 

 1 I was actually led to adopt this important modification, perhaps, by 

 a mere chance. In the spring of last year Mr. Temple Orme, of 

 University College, had kindly undertaken to perform some experiments 

 with me bearing upon this subject. One day, however, he told me he 



