CHEMICAL PHENOMENA IN LIFE 



believed, and that it was the active cause of the 

 fermenting. From that time yeast has been placed 

 in the plant system among the fungi. A little later 

 Kutzing was able to show that the cause of acetic 

 fermentation was also a microscopic plant, be- 

 longing to the bacteria. It is still well remembered 

 what great services Louis Pasteur rendered to the 

 knowledge of microbes which cause different 

 fermentations. In consequence of these dis- 

 coveries the name of ferments was transferred to 

 the microbes causing fermentation. I have 

 already taken the opportunity of mentioning a 

 further wonderful discovery of the remarkable 

 third decade of the last century. I mean the 

 isolation from germinating seeds of a substance 

 which is able to transform starch into sugar. 

 Payen and Persoz first showed that extract of 

 malt contained a certain substance, soluble in 

 water, and which was precipitated by alcohol, 

 which causes the starch grains to dissolve and 

 induces the formation of sugar from starch. The 

 two French scientists even showed that this sub- 

 stance, to which was given the name of Diastase, 

 immediately loses its power when boiled. Theo- 

 dore Schwann, at about the same time, discovered 

 that from the mucous membrane of the stomach 

 there can be extracted a substance which is soluble 

 in water or glycerine, and which acts very effec- 

 tively upon albuminous compounds, quite in the 

 same way as in digestion the living organ changes 

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