178 MODERN SCIENCE READER 



be safer in saying, by the general tendency, under defined 

 conditions, for reversionary processes to become manifest. 

 It is rather more than twenty years ago since Dr. Wohl 

 noted the phenomena of inversion and reversion in connec- 

 tion with the action of weak acids on certain complicated 

 sugars. 



If further evidence be required as to the possibility of 

 what I have named constructive ferments, it may be found 

 in Emmerling's work, which I mention with reserve, on 

 amygdaline. Under the influence of one enzyme, emulsin, 

 this substance is split up into sugar, hydrocyanic acid, and 

 the essence of bitter almonds. But it is said that another 

 ferment, maltase, common to yeast, will join these decom- 

 position products together again to form the original 

 substance. 



On one very particular point, that is to say, the mole- 

 cular construction of these enzymes, ferments, or diastases, 

 the world of science is almost entirely ignorant. This ques- 

 tion forms one of the many chemical problems of the hour, 

 and we start with the shallow fact that they contain the 

 simple elements found in charcoal, air, and water. Beyond 

 this we know next to nothing. I think, however, we may 

 console ourselves with the reflection that we are at least on 

 the eve of important discoveries. My friend, and former 

 " chief," Emil Fischer, of Berlin, having vied with Nature 

 herself in the manufacture of sugars, has now turned his 

 attention to proteid substances. The intervening gulf has 

 already been bridged, inasmuch as Fischer has traced tho 

 connection between the configuration of a sugar and its 

 behavior toward ferments. This is the famous "Schloss 

 und Schlussel" theory, the happy analogy of "lock and 

 key." It is our every-day experience that yeast cells 

 assimilate more easily the sugars of which the molecular 

 configuration closely resembles that of the most digestible 

 of all carbohydrates, namely, glucose. Many of the arti- 

 ficially produced sugars, as for example the al doses, gulose 

 and talose. are quite indifferent to the fermentive efforts 



