1911] _ SCHREINER & SULLIVAN—ROOTS 283 
activities of the roots per se, and is probably due to the presence 
of some unsaturated compounds comparable to unsaturated fatty 
acids, dextrose, etc., which are readily oxidized in contact with 
air, or to substances like organic hydroxyacids and their salts 
which possess a slight reducing action. 
In regard to the significance of the oxidation and reduction in 
roots, we may say that whatever increases the development of the 
plant increases oxidation by the roots, and contrariwise, whatever 
decreases oxidation by the roots decreases the growth of the plant. 
In short, oxidation is closely connected with the metabolic activi- 
ties of the roots. It has been shown (3'7) that in extracts from pro- 
ductive soils oxidation by roots was strong, and in extracts of certain 
Poor soils the oxidation was little, so that from a soil-fertility 
standpoint oxidation by roots has considerable interest. Oxida- 
tion is due undoubtedly to bodies capable of fixing atmospheric 
oxygen in an active form, perhaps as peroxides, which secondarily 
oxidize bodies by the transfer of active oxygen to them. Reduc- 
tion seems to be connected with the inner metabolism of the plant, 
and is probably brought about by non-enzymotic compounds anal- 
ogous to the organic hydroxyacids and their salts, which have a 
reducing action easily demonstrable by their changing of ferric 
iron to ferrous iron, or to compounds unsaturated in respect to 
oxygen, which by their avidity for oxygen reduce the oxygen- 
containing compounds they come in contact with. Oxidation 
Processes are weak in the young seedling, but increase in strength 
as the seedling grows. Reduction processes, on the other hand, 
are predominant in the early stages of the seedling’s growth, but 
are less manifest as the seedling develops and oxidation becomes 
Predominant. In certain stages the two processes occur together 
and can be made manifest either independently or concurrently. 
Reduction seems to be mostly intracellular. Oxidation, on the 
other hand, is manifested strongly extracellularly, and seems to be 
by far the more prominent property of the plant root. 
BurREAv oF Sorts 
U.S. Department oF AGRICULTURE 
Wasuincton, D.C. 
