113 
In this manner we account for tlie oxidation of guaiacum, potassium 
iodide, and hydroquinon by atmospheric oxygen through the inter- 
mediate action of the vegetable oxidase. This theory also enables 
us to understand the instability of these substances. 
Diagrammatically, these changes may be represented as follows: 
( 1 ) 
and 
(2) 
or 
(3) 
and 
(4) 
(Oxidase) 
A + 0 2 = -40 2 , 
(Oxidase) 
A0 2 + B = AO+BO, 
A0 2 + 2B=A+2B0, 
A0 2 + A =2 AO. 
In this connection see also Engler and TTeisberg ( 164 ), supra. 
In the above equations A is the autoxidizable substance or sub- 
stances contained in the plant or animal which is the immediate pre- 
cursor of the oxidase. A0 2 is the oxidase resulting from the union 
of A with molecular oxygen, and B is the substance oxidized by the 
oxidase, as, for example, guaiacum, phenolphthalin, or hydroquinon. 
If the change proceeds as indicated in equation (2), both the pre- 
cursor of the oxidase and the second oxidizable substance (the oxi- 
dase reagent) will be completly oxidized, and the oxidase will not be 
regenerated as the result of the oxidation, but will be destroyed. 
On the other hand, if the oxidation proceeds according to equation (3), 
the precursor of the oxidase will be regenerated, and at the end of 
the process will be in a condition to again enter into the cycle of 
changes indicated in equations (1) and (3). Finally, it is con- 
ceivable that the oxidase may oxidize a second part of A, in which 
case, as indicated by equation (4), both the precursor of the oxidase 
and the oxidase itself will be destroyed. As a matter of fact, it is 
known that solutions of oxidases gradually lose their oxidizing pow- 
ers; this is readily intelligible in the light of equations (1), (2), and 
(4), especially in view of the fact that all living tissues and extracts 
contain powerful reducing substances which in the processes under 
consideration would function as B in equation (2). 
In support of the view that the oxidases are really peroxides, we 
may cite the following observations of Bach and Chodat( 26 ): The 
fresh sap of the Lathrxa squamaria, which contains an oxidase, was 
subjected to the action of a current of air and a 1 per cent solution 
of barium hydroxide was added drop by drop. A precipitate is 
formed under these circumstances which is found to contain barium, 
and when decomposed by sulfuric acid the resulting solution gave 
11670— Bull. 59-10- 8 
