LIBERATION oF ORGANIC MatTTEeR BY Roots oF GROWING PLANTS 39 
rhether the reducing substances were of that nature in view of the results 
ith reduction of nitrates. 
Oxidizing substances 
Peroxidases were detected in the culture solution in which the roots 
{ maize, vetch, oats, peas, soybeans, alfalfa, and timothy had grown. 
rom 8 to 10 cubic centimeters of each solution was placed in a dry test 
abe together with a few drops of hydrogen peroxide. This was allowed 
) stand for from two to three minutes, and then from two to three drops 
f a 5-per-cent phenol solution were added.’ The latter was then followed 
y an alcoholic solution of guaiac. It was considered that a positive test 
as recorded if the color became blue in thirty minutes. With this test 
o difficulty was experienced in obtaining a reaction with solutions from 
ll of the flasks tested. Boiled solutions treated ikewise gave no reactions. 
In working with the solution in which vetch roots had grown, a very 
rong reaction was obtained by the use of hydrogen peroxide and phenol. 
‘he solution was placed in dry test tubes and a few drops of hydrogen 
eroxide were added. This was allowed to stand at room temperature. 
fter from three to four minutes a few drops of a 5-per-cent phenol solution 
ere run down the side of the test tube. Shortly after contact of the 
laterials, a growing yellow color developed, which gradually increased 
od on long standing settled out. . This test was negative when the same 
ution was boiled. An extract of macerated vetch roots and nodules 
ave the same test. If this material was boiled, however, no reaction 
as obtained. 
Phenolpthalin was used as a reagent for indicating the presence of 
sidizing substances in the solutions in which maize plants had grown. 
or these tests both boiled and unboiled samples of the solutions were 
sed. Checks consisting of the nutrient solution in which no plants 
ad grown were also included. Phenol was added, as in the previous 
ists. Results from these tests were usually negative. 
Experiments in which guaiac were used without a peroxide indicated 
le presence of an oxidase in solutions in which maize plants had grown 
aly when the plants were very young. Agar in which timothy plants 
ere grown always gave a reaction with guaiac. 
Tests with pyrogallol included only one sterile flask. No phenol was 
sed. At the end of one-half hour the boiled solution was clear, the 
