NITROGENOUS SOIL CONSTITUENTS 



55 



TABLE IV 



Effect of hypoxanthine on growth in cultures containing no nitrate 



FERTILIZER INGREDIENTS IN CULTURE 

 SOLUTIONS 



<!la,K.V WEIGHT OP CULTURE 







NHs 



K20 



\\lthout hypo- 

 xanthine 



Yt itn luu p.p.m. 

 hypoxanthine 





p.p.tn. 



p.p.m. 



p.p.m. 



grams 



grama 



56 



0 



0 



80 



1.178 



1.370 



46 



8 



0 



72 



1.390 



2.190 



37 



16 



0 



64 



1.320 



1.628 



29 



24 



0 



56 



1.250 



2.059 



22 



32 



0 



48 



1.309 



2.220 



16 



40 



0 



40 



1.320 



2 . 100 - 



11 



48 



0 



32 



1.300 



2.198 



7 



56 



0 



24 



1.465 



1.820 



4 



64 



0 



16 



1.49S 



1.720 



2 



72 



0 



8 



1.190 



1.655 



1 



80 



0 



0 



1.000 



1.055 



every case an increase in the hypoxanthine culture, although this 

 naturally varies in the different combinations of phosphate and 

 potash in these cultures. The total green weight of the series 

 without hj^poxanthine is 14.220 grams, against 20.015 grams in 

 the hypoxanthine cultures, or an average increase of 41 per cent. 



Growth in cultures containing eight parts per million NH3 as nitrate 



Table V gives the effect which hypoxanthine had when added 

 to culture solutions which already contained a small amount of 

 nitrate. This is the series of cultures containing uniformly 8 

 parts per million of NH3 as nitrate, but varying amounts of 

 phosphate and potash as is shown in Table V. As in Table IV 

 the comparison of the last two columns shows that the hypo- 

 xanthine cultures are heavier in each case, but the difference is 

 not near so great. The total green weight in the series of cul- 

 tures without hypoxanthine is 20.707 and with hypoxanthine it 

 is 23.672 grams, an average increase of 14 per cent, as against 

 the 41 per cent shown in cultures given in Table IV. 



