( 3 ) 



enzviiie |tarli('l(\ hefoi'e the distaiu-c li;is hecome so fircat thai iho 

 radiation fails to cause inversion, eaeh en/ynie particle is hound to 

 exert the same action. One nii<;ht compare an enzyme particle iji 

 concentrated sugar solutions with a source^ of liniit in a fog of 

 varying density ; the denser the fog the smaller Ihe region around 

 the source of light which absoi-bs all the light. 



If, howexer, canesugar absorl)s the raihation from inverlin, we. 

 must expect the same to a greater or smaller extent from the products 

 of inversion. On account of this power of ahsorhiug the active rays 

 these })roducts must retard the inversion. 



The result of my often-repeated experiments showed that the inversion 

 of canesugar hy in\'ertin prepared from carefully dried yeast (we 

 shall see, presently, that the method of pre[)aring the invertin is of 

 the greatest importance) is retarded equally by glucose, laevulose and 

 invert sugar. 



For instance, the same amount of yeast-extract inverted under the 

 same conditions ^) from 



107„ canesngar 49.37, 



107„ canesugar -f 57„ glucose 38.57„ 



107o canesngar + -^Vo laevulose 38.37o 

 10"/(, canesugar + 5"/^ in\'ert sugar 38.3''/„ 



From the similarity of the last three figures it is already evident 

 that we are not dealing here with a retardation due to a reversed 

 reaction. 



It \vas further ascertained that the other hexoses cause exactly 

 twice as much retardation as glucose or laevulose : 



87o canesngar •43.(7/o inverted 



87o canesugar -\- 27o galactose 35.57n ,, 

 87fl canesngar -|- 27» mannose 36.i7o m 

 8"/„ canesngar -|- 4"/„ glucose 36.17„ ,, 



From these results it is evident that the inxersion phenomena 

 beliave as if there are emitted by an invertin |)article two radiations 

 in equal quantity which we may call, provisionally, glucose and 

 laevulose radiations. Each radiation Ity itself is capable of inverting 

 a canesugar molecule ; the glucose radiation is not absorbed by the 

 gincose but by the laevulose; the laevulose l)ehaves, conversely, 

 in the same way. Iji accordance with this both radiations are 

 absorbed by any other hexose. We may, therefore, regard invertin 



1) All sugar delermiuations have been made by Kjbldahl's acciuale gravimetric 

 process. 



1* 



