1911] SCHREINER & SULLIVAN—ROOTS 277 
the depth of the red oxidation product was measured in the color- 
imeter with the oxidation products of plants growing in carbon- 
treated water plus aloin as a control. 
TABLE II 
RELATIVE OXIDATION OF ALOIN BY ROOTS IN DARKNESS AND IN LIGHT 
In darkness In light 
ie dag lie hes: was os oe ey Ss 100 70 
on oe ap doe REE a ately Tae 150 105 
Se MIGNON gs a ee 902 47 
women chlogia 0 ie oe Soe 60 
eres Uikhide ee Ree 66 37 
Since BIELECKI (12) has shown that nitrates of potassium, 
ammonium, and calcium added to a solution of peroxidase lead 
to its passing through a dialyzer in amounts proportionate to the 
amount of salt added, it may be that the nitrates increase the 
oxidizing activity of the wheat roots by allowing more of the oxidiz- 
ing substance to pass into the medium. With alcoholic guaiac as an 
indicator, we have found a strong peroxidase reaction in the water 
in which the seedling roots had grown for 24 hours, and a stronger 
reaction in sodium nitrate solution in which plants have grown the 
same length of time. This peroxidase reaction does not occur if 
the culture water is boiled. 
The observable action of salts on the reducing action is variable 
on account of lack of precision of method, though, as a rule, sodium 
nitrate equivalent to 50 p.p.m. NH, gives the quickest and heaviest 
deposit at the root tip, while potassium salts give the heaviest 
deposit on the rest of the root. The potassium salts which retard 
oxidation have little effect on reduction. Thus a potassium 
iodide solution containing 14.5 p.p.m. K,O practically inhibited 
the oxidation of aloin by the roots of 5-day old wheat seedlings, 
while allowing good reduction of sodium selenite. It would seem, 
then, that reduction and oxidation may be independent of each 
other. 
Attempts were made to show simultaneous oxidation and reduc- 
tion by placing the seedlings with the roots in mixtures of sodium 
selenite and aloin, benzidine, and alpha-naphthylamine, respec- 
tively. In mixtures of sodium selenite and alpha-naphthylamine, 
