54 ' OSWALD SCHREINER AND J. J. SKINNER 



beneficial effect of the nucleic acid, it is especially interesting to 

 know the effect which this rather definite soil constituent, to be 

 considered as a product resulting from nucleic acid, has upon 

 plants. 



In testing the effect of hypoxanthine on wheat seedlings, the 

 experiment was conducted in every way similar to that described 

 under nucleic acid. Two sets of the 66 nutrient cultures were 

 prepared, the one having added to each culture 100 parts per 

 million of hypoxanthine, the other set being used as a control. 

 The seedlings grew from February 1 to February 13. The solu- 

 tions were changed every three days as before. In the case of 

 the nucleic acid cultures, onl}^ the nitrates had been determined, 

 but in the case of hypoxanthine, in addition to the determination 

 of nitrate, immediately after making the change of solutions 

 in the cultures, the phosphate and potash were determined on a 

 composite of the four changes in each culture. Only the cultures 

 containing all three fertilizer elements were thus analyzed. It 

 was apparent almost from the start that the hypoxanthine set 

 of cultures was making better growth than the set not containing 

 this substance. The plants were better developed, had broader 

 leaves and longer and better developed roots. These effects 

 were especially noticeable in the cultures containing no nitrate 

 when these were compared with the same cultures in the control, 

 set. 



The green weight of the cultures was taken at the termination . 

 of the experiment. The total weight of the 66 normal or control 

 cultures was 139.4 grams against 150.1 grams for the 66 cultures 

 with the hypoxanthine. With the normal at 100 the hypoxan- 

 thine cultures become 108, or an average increase of 8 per cent for 

 all the cultures. The effect, however, was most marked in those 

 cultures in which nitrate was absent or low as will now be shown. 



Growth in cultures containing no nitrate 



Table IV gives the growth in the series of cultures in both 

 sets, with and without hypoxanthine, which contained no nitrate. 

 The comparison of the last two columns of the table shows in 



