Igt1] SCHREINER & SULLIVAN—REDUCTION BY ROOTS 127 
death phenomenon, since (1) roots killed by being dipped in boiling 
water have no reducing action on the selenite; (2) the roots in. 
toxic non-neutralized sodium selenite do not reduce; (3) intact 
roots boiled in solution of sodium selenite have no deposit of sele- 
nium upon them; (4) the root ends being cut off and the injured 
root placed in the selenite solution, the deposit of selenium is not 
on the cut end but at the point of emergence of the secondary roots. 
The reducing power of the wheat roots on sodium selenite is 
checked by acids and alkalies and by toxic organic matter. It is 
stimulated by faintly acid reaction and by light. 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 solution 
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. Potassium salts containing 50 p.p.m. K,O appeared 
to retard reduction slightly at the root tip. Potassium iodide 
containing 14.5 p.p.m. K,O, however, stimulated reduction. 
Incidentally it is of interest here to state that potassium retards 
greatly the oxidation power as indicated by aloin, and that a 
slight acid reaction stimulates reduction while inhibiting oxidation, 
thus seeming to show that the reducing and oxidizing powers are 
not necessarily concomitant. 
Whether or not the reducing power of the wheat roots on sodium 
selenite is due to enzyme activity, it is hard to say positively. 
In regard to the enzyme nature of the reducing agent in animal 
cells, HeEFFTER (26) concluded that there were two groups of 
reduction processes. One group was hardly influenced by hydro- 
chloric acid or by heating. This group embraced the formation 
of hydrogen sulphide from sulphur, the reduction of arsenic, 
tellurium, and selenium compounds, the reduction of cacodylic 
acid and of different dye-stuffs. These reductions he believes are 
caused by the labile hydrogen of the sulphydryl group of certain 
albuminous bodies. The other group of reduction processes, such 
as the change of nitrates to nitrites and of nitrobenzol to amino 
combinations, were restrained by heat. This group of reactions he 
thought at first might be enzymotic, but later he came to the con- 
clusion (26) that they likewise were non-enzymotic. 
