20 



alone is possible under such conditions. Some plants, 

 common in swamps, have acquired partial immunity to these 

 toxins. 1 Perhaps other plants are able to live under 

 such conditions without producing toxins at all. 

 Others may be able to dispose of toxins, as, for instance, 

 by allowing them to pass upward with the transpiration 

 stream to the aerial portions of th plant, where atmo- 

 spheric oxygen is available to complete the oxidation. 

 If respiration Jm not too vigorous the transpiration 

 stream might easily be competent to sweep out in this 

 way all of the intermediate respiration products pro- 

 duced in the roots. . Once these products are removed 

 to the aerial portions of the plant the completion 

 of their oxidation presents no difficulty. 



It is perhaps even more significant, especially 

 a*t J air /culture 

 for ecology* /that reactions occurring in the soil itself 



have much effect on the accumulation of thftse toxic 



intermediate products. All soils appear to have a 



certain power of destroying or removing these substances 



by oxidation, adsorption or in some other wajr now 



1. Ooville,- The agricultural utilization 

 of acid lands by means of acid-tolerant crops, U. S. 

 Dept. of Agr., Bull. 6, 1913. 



