CHAPTER V 



THEORIES AS TO MODE OF ACTION OF CATALYSTS AND 

 ENZYMES CORRELATION OF THEORIES MEANS OTHER 

 THAN CATALYSIS BY WHICH CHEMICAL REACTIONS CAN 

 BE INDUCED, OR REACTION VELOCITY VARIED 



I. The Theory of Molecular Vibrations. Theories having a bear- 

 ing upon catalytic action first began to be formulated for the 

 purpose of giving some explanation of the processes of fermentation 

 which at the time occupied the attention of the chemist more than 

 of the biologist. The brilliant work of Pasteur had not as yet 

 illuminated the action of micro-organisms in these processes, when 

 Liebig, search' ng for some explanation of the action of yeast upon 

 glucose, evolved the theory that such action arose because the 

 yeast was itself involved in a process of chemical activity or decay 

 and provoked as a result chemical activity in the sugar. In 

 support of his theory Liebig adduced many examples from 

 inorganic chemistry of where the chemical activity of one body 

 influences that of another, and of cases where even mechanical 

 vibration causes changes, as in explosive bodies, such as the iodide 

 or chloride of nitrogen. 



It is not to be wondered at that Liebig in those early days 

 looked upon those activities which are now known to be due to 

 micro-organisms as due to chemical action entirely. 



Many of the experiments carried out by Liebig and others of 

 his school of thought, to attempt to exclude the possibility of 

 micro-organisms being present, were well and scientifically thought 

 out, and if they led the distinguished chemist into error, it was 

 only because of failure to realise at that early date the difficulty 

 not only of maintaining but of preserving complete sterility. When 

 one reads the experiments by which it was sought to prove that 

 it was the access of air and not the presence of micro-organisms 

 which conditioned fermentation, one is forced to admit that they 



126 



