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1911] SCHREINER & SULLIVAN—ROOTS 279 
cell, the cell generates a third ferment, catalase, which decomposes 
the peroxide with the liberation of molecular oxygen. 
According to Moore and Wuittey (13), there is little evidence 
of the existence of BAcH’s oxygenase. These workers believe that 
all juices showing oxidizing properties possess one type of ferment 
which, since it acts only in the presence of either naturally occurring 
or artificial peroxide, may be styled a peroxidase. According to 
them there is no proof of the existence of any other type of enzyme 
engaged in oxidation processes. 
In regard to cellular oxidation, it must be said that nothing 
absolutely certain is known regarding the composition or nature 
of the oxidizing substances in plants and the chemistry of the 
oxidizing bodies is uncertain. Apart from their destruction by 
heat and by poisons, little is known concerning their enzymotic 
nature. They do not seem to act as oxygen carriers in the sense 
of being able to transfer large amounts of oxygen from the air to 
the oxidizable substance, since the amount of oxidation is increased 
only slightly by an increase in the amount of oxygen present. Thus 
the relative oxidation by the roots of plants growing 4 hours in an 
atmosphere of pure oxygen and of air, respectively, was too and 8o. 
The relative oxidation by plants in air and in a partial vacuum of 
a pressure of 23 mm. of mercury for 4 hours was 100 and 66; grow- 
ing 19 hours in a partial vacuum, too and 74, respectively. In 
the partial vacuum the plant must oxidize the aloin by means of 
its intramolecular oxygen. In an atmosphere of carbon dioxide, 
oxidation was begun early, but this then stopped, and in 16 hours 
Was a mere trace compared to the oxidation by plants growing in 
aloin solutions in air. Oxygen is necessary for plant oxidation, 
but a great increase in the amount of oxygen does not greatly 
imcrease the oxidation by plants. 
Many, if not all, of the oxidations produced by the so-called 
€nzymes can be brought about by non-enzymotic bodies, bot 
organic and inorganic, as first shown by ScHGNBEIN (14). Organic 
bodies like benzaldehyde, benzoyl peroxide, succinyl peroxide, 
Pyrogallic acid, and quinone behave like an oxidase, as do peroxides 
and other salts of inorganic bases such as iron, lead, manganese, 
ac. 
