1909] SCHREINER & REED— OXIDIZING POWER OF ROOTS 379 



which also possessed a strong oxidase reaction. The roots of 10 wheat 

 eedlings 12 days old were removed and crushed in a mortar uith 

 distilled water. The filtered liquid obtained from this source gave 

 a strong reaction for oxidase when tested with guaiac. As before, 

 i cc of aloin solution I or II was added to 5" of the root extract in 

 test tubes, according to the plan in Table IX. The tubes were pre- 

 pared and aloin added at 4.30 p. m. on January 13, and the observa- 

 tions recorded in the third column of the table were made at 1 1 a. m. 

 on the following day. 



TABLE IX 

 Comparative reaction of aqueous and alcoholic solutions of aloin to a liquid 

 containing oxidase. 



Solution 



Root extract + i cc aqueous aloin 

 Distilled water + i cc aqueous aloin 

 Root extract + 1 cc alcoholic aloin 

 Distilled water +i cc alcoholic aloin 



Color observed 

 11 a.m., January 14 



red 



faint pink 

 pronounced pink 



faint pink 



The results of these experiments supplement those of the fore- 

 going in which a peroxidase liquid was used, by demonstrating that 

 the oxidase caused a much greater conversion of aloin to "aloin red" 

 *ith the aqueous than with the alcoholic solutions of aloin. There 

 *as in the root extract a distinct peroxidase reaction to guaiac, to 

 Edition to the oxidase reaction, and it is therefore only natural that 

 in tubes 6, 7, and 8 there should be some development of color when 



alcoholic aloin was added. 



It is evident, from the above results, that in the absence of living 

 Pknt roots aqueous aloin is principally a reagent for oxidase and 

 Acholic aloin for peroxidase. In the experiments where plants are 

 ^Ployed it is however needless to say that only aqueous solutions 



of aloin can be used. ... 



Aloin and phenolphthalin having shown their usefulness as indi- 



r^_ r r . i__a *„ ,rprp investigated 



enzyme 



for comparison. Leuco-rosolic acid was prepared by reducing 

 ro * acid with zinc dust in alkaline solution. When reduction 

 Was Practically complete, the solution was filtered and neutralized 

 ■* hydrochloric acid, then rendered slightly alkaline with sodium 



