162 BOTANICAL GAZETTE [SEPTEMBER 
is a difference in the nature of the chemical bodies in different 
soils. Some of the bodies isolated contained nitrogen, while others 
free from this element contained carbon, hydrogen, and oxygen 
only. The presence of sulfur and phosphorus compounds has also — 
detailed knowledge of their nature and properties seems imperati , 
in order to know and understand the nature of the material infiag 
and reduction or by microbiologic and enzymotic influences. 
In an earlier paper? it was demonstrated that the roots of p “ s 
of the normal root was found to be iAaensed by the medium 
which it grew. Thus good soils and their aqueous extracts PI 
moted oxidation, while the poorer soils hindered this function | 
the roots. Some substances harmful to plant growth were 
found to have an inhibitive effect on this oxidation. When sma 
amounts were present, however, it was found that the © i 
power of the roots was able to overcome the harmful influ 
An examination in one case, namely that of vanillin, where - 
was possible to demonstrate by colorimetric test the pres 
or absence of minute amounts, showed that this disappé 
entirely from solution under the influence of the oxidizing Pp? 
the roots. It was further shown that the fertilizer salts, in additl 
case of sodium nitrate and lime.t The action of fertilizer. 
and the influence of such harmful soil constituents were fu 
investigated, therefore, and the results given in connection with | 
3 SCHREINER, O., and REEp, H. S., Studies on the oxidizing power of roots. 
GAZETTE 47:355. 10909. See also Bull. 56, Bureau of Soils, U. S. Dept. Agric. 
4 SCHREINER, O., and REED, H. S., The power of sodium nitrate and 
— to decietae toxicity in conjunction with plants growing in solution es 
ur. Amer. Chem. Soc. 30:85. 1908. 
