Dr. Oscar Loew 51 



filtered liquid will become blue very soon. 

 This shows an exceptional case, namely, that 

 the oxidase (laccase) is present in an insoluble 

 state and perhaps held in combination with an 

 insoluble protein. 1 Upon standing, the blue 

 colour, obtained with the unfiltered liquid, will 

 gradually disappear, except on the surface, but 

 on adding a few more drops of the reagent 

 and shaking, the intense blue colour reappears. 

 This phenomenon is due to the presence of a 

 reducing compound in the juice. 



In testing for a second oxidizing enzyme, the 

 peroxidase, the tissue of the seed, crushed 

 with a little water, was heated for five minutes 

 to 75 C. and one portion of this liquid was 

 filtered ; the other not. The test with guaia- 

 cum tincture yielded no blue reaction in either 

 liquid, proving that the oxidase was killed, 

 while on addition of a little peroxide of 

 hydrogen the unfiltered juice gave an intense 

 blue reaction and the filtered juice showed 

 only a trace. This difference proves that the 

 peroxidase, like the oxidase, was present, but 

 retained as an insoluble compound an ex- 

 ceptional case. 



Reactions with guaiacol were also tried. 

 This substance produced no colouration when 

 applied by itself, but in conjunction with 

 hydrogen peroxide a red colour turning to 

 brown was soon produced in both the hard 



1 This recalls the existence of a soluble and insoluble 

 form of catalase. 



