i9i 2] SCH REINER & SKINNER— FERTILIZER SALTS 39 



cumarin and the acid calcium phosphate. The possible solutions 

 of the problem must be left for future investigation. 



From the foregoing results it is apparent that the two toxic 

 substances studied, dihydroxystearic acid and cumarin, show- 

 markedly different physiological properties, and are very differently 

 influenced by fertilizer salts. Whether this is a direct action of the 

 fertilizer on the organic body or through the medium of the plant 

 cells, making the toxic substance and the particular fertilizer salt 

 physiologically antagonistic, cannot be definitely stated. 



The cumarin so affected the normal development of the wheat 

 as to cause stunting of leaf growth, with abnormal appearance 

 associated with a slightly altered absorption of plant nutrients, 

 both as to amount and ratio, the phosphate absorption being the 

 more normal. The fertilizer combinations high in phosphate were 

 the most effective in antagonizing the harmful effect of cumarin. 



The dihydroxystearic acid also affected normal development, 

 causing a decrease in top growth, but no abnormal appearance, the 

 greatest abnormality being in this case observed in the root system, 

 which was darkened and much stunted and showed swollen root 

 tips, often bending into fishhooks, associated with a much altered 

 absorption of nutrient elements both as to amount and ratio, the 

 phosphate and potassium absorption being greatly depressed, the 

 nitrate removal or disappearance being about as under normal 

 conditions, but relatively much greater. The fertilizer combina- 

 tions high in nitrate were the most effective in overcoming the 

 harmful effect of this soil constituent. 



In view of this widely different behavior of these two toxic sub- 

 stances, entailing the interesting observation that they responded 

 differently to the different fertilizer combinations, it was thought 

 desirable to consider some results with other toxic substances. 

 In the first place, it was interesting to see whether the result 

 observed with dihydroxystearic acid, namely response to the nitrate, 

 was shown by another toxic body, and thus throw a little more 

 hght on this phase of the question. For this comparison the 

 aldehyde vanillin was selected. This was known to be toxic from 

 former experiments, was known to be oxidized by the plant roots, 

 and was further known to be more readily oxidized when nitrates 



