Chap, viii Respiration 



427 



absence of oxygen, and that such life is associated with 

 the carrying on of the processes of fermentation. In con- 

 sequence of his researches he put forward the view that 

 fermentation, alcoholic especially, is life in the absence 

 of oxygen. The views that were then obtaining currency 

 on the combustion relations of respiration led him to hold 

 that the object of fermentation is to replace the oxygen 

 of the air, now no longer supplied, by the intramolecular 

 oxygen of the substances undergoing fermentative changes, 

 especially sugar. In this way a supply of oxygen would 

 be made available for the combustion which he held to be 

 essential. All the changes being held to be readjustments 

 of the structure of the molecule of the fermenting body, 

 whether free or in the living asphyxiating substance, the 

 term intramolecular respiration was applied to the process. 



The investigations of Pasteur were followed in 1869 and 

 1872 by the researches of Lechartier and Bellamy, who 

 studied the behaviour of various succulent fruits, potatoes, 

 and grains of wheat, when kept in closed vessels without 

 access of air. They gradually absorbed all the free oxygen 

 around them and still exhaled carbon dioxide after it had 

 disappeared. Pasteur himself confirmed these observations. 



Investigations published by Brefeld in 1876, and by 

 De Luca in 1878, showed that similar results were met with 

 in experiments with seeds, leaves, and branches. These 

 researches were confirmed and extended by many observers. 

 So general has the process been ascertained to be, that it 

 is exhibited in the trunks of trees, supervening there on 

 normal respiration, as was shown by Devaux in 1899. 



This so-called intramolecular respiration was found to be 

 accompanied by the formation of many products which do 

 not occur in the normal respiratory processes. The occur- 

 rence of alcohol has long been associated with the process 

 of fermentation by yeast, though the action of yeast may 

 perhaps differ in some particulars from the anaerobic 



