132 



8. The addition of potassium and phosphorus 

 greatly increases the beneficial eiTects of pyridine and 

 quinoline. 



9. The action of potassium and phosphorus in in- 

 creasing the etfectiveness of pyridine and quinoline 

 cannot be regarded as an antitoxic action. These two 

 mineral elements greatly increased the effect of aspara- 

 gine, nucleic acid, and nitrate of soda, none of which 

 is toxic to plants. 



10. Dihydroxystearic acid had absolutely no bad 

 effect on either oats or corn. Larger yields of both 

 crops were obtained in the presence of dihydroxystear- 

 ic acid and a complete fertilizer, than with a complete 

 fertilizer alone. 



11. Xaphthylamine, a nitrogenous compound, is 

 slightly beneficial to oats and corn, but apparently it 

 is changed very slowly in soils; and unless it is de- 

 composed, it has no effect one way or another. 



12. Asparagine and nucleic acid, neither of whicli 

 is toxic to plants in solution cultures, proved to be very 

 beneficial when used in soil cultures. 



13. A normal soil can apparently dispose of enor- 

 mous quantities of organic compounds through physi- 

 cal, chemical, and biochemical action. 



14. The results obtained with soil cultures fail to 

 agree with those obtained with solution cultures, when 

 the aim is to show the toxicity or non-toxicity of chemi- 

 cal compounds. 



15. Soil fertility problems cannot be solved by 

 means of short time solution culture studies. Soil fer- 

 tility studies with the soil left out, cannot be depended 

 upon to answer correctly the complex questions in- 

 volved in soil fertility work. 



