104 ORIGIN OF LOWEST ORGANISMS. 



was filled by the experimental fluids.* Gruithuisen's 

 results were explained by Burdach on the ground that 

 a certain amount of air was necessary, and it was also 

 with the view of subjecting his fluids to as large an 

 amount of air (calcined) as possible, that Professor 

 Wyman employed small quantities of fluids in large 

 flasks. These views were dictated by the chemical 

 doctrines of Gay-Lussac and others, to the effect that 

 the oxygen of the air is the initiator or priinum 

 movens of fermentative changes.! 



Now, without doubting in the least that in some 

 instances this may be the case, it seems to me quite 

 obvious, from my own experiments, that a different 

 interpretation may be given of Gruithuisen's results- 

 which r have myself verified, and of the fact that 

 meats and vegetables will often remain unchanged for 

 years after having been heated in closed tins from 

 which all air has been expelled. J 



If we ponder only upon the fact that certain fluids, 

 in contact with a very small quantity of air, in an 

 hermetically-closed vessel, will not undergo change ; 

 though these same fluids will change when exposed 



* 'American Journal of Science,' July, 1862. 



t See Gerhardt's, ' Chimie Organique.' t. iv. pp. 540 and 547. 



J It was, indeed, the consideration of these latter facts which 

 originally forced Gay-Lussac to the conclusion, that fermentation 

 would not take place in vacua, or without the presence of 

 free oxygen, which was and still is, believed by many, to be the 

 immediate determining cause of fermentation. 



