CHEMICAL PHENOMENA IN LIFE 



effects were recognised in the formation of prussic 

 acid from the so-called amygdaline in germinating 

 bitter almonds, in the formation of the sharp 

 essential oil in germinating mustard seed, and, 

 finally, in protein digestion in the stomach of man 

 and the higher animals. Berzelius did not hesitate 

 to express his opinion that catalytic reactions 

 will probably one day represent the most im- 

 portant part of the chemistry of living cells. 



At present, indeed, we have at our disposal a 

 surprisingly great mass of facts which illustrate 

 the general occurrence of catalytic substances in 

 living cells and the overwhelming importance of 

 catalytic reactions for chemical phenomena in life. 

 I shall try to explain the position of our knowledge 

 in the following pages as well as it is possible to 

 do in a narrow space. 



To Ostwald, of Leipzig, we owe a very ingenious 

 and practical definition of catalytic reactions and 

 catalytic power. Substances which act as Cata- 

 lysers, as we now call them, usually exert their 

 influence upon a suitable substance, even when 

 applied in very small quantities. As a rule one 

 part of the effective substance may transform 

 many thousands, even millions of parts of the 

 substance undergoing the catalytic change. But 

 during the reaction the quantity of the catalyser 

 does not diminish. For instance, when splitting 

 up cane sugar into glucose and fructose by means 

 of acid, the acidity of the solution does not show 

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