60 



OSWALD SCHREINER AND J. J. SKINNER 



cussed, but not sufficient material was at liand, either from soil 

 or other source, to make any study of its effect on plants. 



SUMM.ARY 



Nucleic acid and its decomposition products, hypoxanthine, 

 xanthine, guanine, and adenine, occur as soil constituents. Nu- 

 cleic acid, hypoxanthine, xanthine, and guanine were studied in 

 regard to their effect on plant growth. All of the compounds 

 were found to be beneficial to growth. 



The beneficial effect was found to be most marked when 

 nitrate was absent from the cultures, showing that the com- 

 pounds are utilized by the plants in their growth. 



When nitrate was present, the addition of the organic nitrogen 

 forms was less effective in producing additional growth than when 

 added to cultures containing no nitrate whatever. Analysis of 

 the culture solutions, however, clearly showed that less nitrate 

 was consumed by the plant when the nucleic acid or hypoxan- 

 thine were also present in the culture solution, showing that 

 these organic nitrogenous compounds are able to replace nit-rate 

 in producing growth. 



