* 



3 86 



BOTANICAL GAZETTE 



MAY 



chemical tests. It now appears that while this destructive action 

 of the plant upon the toxic body is going on, the oxidizing power in 

 the presence of an excess, as it were, of toxic body is greatly reduced, 

 and may even be entirely inhibited. The conclusion drawn from 

 those experiments was that the plant roots are able to oxidize a 

 certain amount of deleterious organic material, and that the presence 

 of salts which favor oxidation increases the ameliorating action of the 



plant. 



This question was studied a little further by an experiment in 



which the oxidation in solutions of toxic 



material 



solution 



without the addition of fertilizer ingredients, was used as a medium 

 for plant growth and subsequently examined for powers of oxidation. 

 Sodium nitrate was added to one portion of the cultures at the rate 

 of 50 parts of N0 3 per million, and calcium carbonate at the rate of 

 2000 parts per million was added to another portion of the cultures. 



Wheat 

 October 17. 



estim 



Table 

 the 



XIII gives the effect of this treatment upon growth and upon 

 oxidation in the toxic solutions and in control solutions to which no 

 cumarin had been added. In each case growth and oxidation 

 the plants in distilled water are taken as 100. 



TABLE XIII 



Effect of sodium nitrate and calcium carbonate on growth and oxidation 

 tions of cumarin. Growth expressed in terms of relative transpiration 



No. 



1 

 2 



3 

 4 



5 

 6 



Solutions 



Distilled water 



U it 



a 



a 



Cumarin 10 p.p.m. 





(C 



n 



+ NaN0 3 

 + CaC0 3 



+ NaN0 3 

 + CaCQ 3 



Relative 

 growth 



100 

 196 

 170 



81 



159 

 110 



Relative 

 oxidation 



100 

 3^0 

 166 



3 1 



139 



I3 1 



ones 



The results of this experiment show, in harmony with the pre^ ^ 

 , that the addition of these fertilizer ingredients overcame 



large extent the deleterious effect of the cumarin upon grow ^^ 

 one making the cumarin solution to which it was adde a ^ 

 medium for growth than distilled water. An inspection of t e 



