19 1 2] Chemical Interpretation of Vital Phenomena. 273 



lation are such as in the laboratory involve the use of the strongest 

 boiling acids : that if the syntheses effected in living organisms can be 

 accomplished at all in vitro, it is only by a succession of countless 

 laborious operations that it would be impertinent to compare with the 

 operations of life. 



The only clue that we seem to have at present to give us confidence 

 in the future of science revealing to us further chemical interpretations 

 of the phenomena of life is one that had its origin about the same time 

 as Wohler's synthesis of urea, in the first observations of Berzelius on 

 what he called catalysis. Certain substances, platinum, silvei and or- 

 ganic substances such as fibrin, have the power of decomposing hydrogen 

 peroxide into oxygen and water without themselves undergoing any 

 change. He compared this process to what takes place when sugar is 

 fermented by an insoluble body known as a ferment and converted into 

 alcohol and carbonic acid, a change which could not be explained as a 

 double decomposition between the sugar and the ferment. We have 

 reasons, he said, well founded on fact for making the assertion that in 

 living plants and animals there take place thousands of catalytic pro- 

 cesses between tissues and fluids. Twenty years later the first physi- 

 ologist of the day, Carl Ludwig, prophesied that some day perhaps physio- 

 logical chemistry might prove to be but a chapter in the chemistry of 

 catalytic action. And there are reasons for thinking that that prophecy 

 is coming true in our own days. 



It is especially since 1897 that the grounds for this belief have grown 

 wider. In that year Buchner showed that a substance could be obtained 

 from the living yeast plant, solutions of which, though entirely free from 

 living organisms of any kind, cause sugar to be resolved into alcohol 

 and carbonic acid, just as the living yeast plants do. The inference is 

 that since this subtance is found in the plant, when the plant ferments 

 sugar it does so because it contains this substance, and not because it 

 is alive. 



Now the difficulty, to which I have alluded, in tracing any similarity 

 between the conditions under which chemical changes are effected in 

 the laboratory and those under which the same changes are brought 

 about where life is manifest, led to the assumption that life was a cause 

 of chemical change. Vital activity, the action of some property of living 

 things, some property not to be defined in any other way and not shared 

 by anything that is not alive, was the only explanation forthcoming for 

 the time to meet this difficulty. The explanation was merely a verbal 

 one, but there was no other. And up to the time of Buchner's discovery, 

 the fermentation of sugar by yeast was the typical instance always cited 

 of fermentation due to the vital activity of an organism or an organised 



