NITROGENOrS SOIL CONSTITUENTS 



49 



of the 11 cultures without nucleic acid, composed of mixtures of 

 phosphate and potash only, was 17.241 grams, against 30.097. 

 grams for the cultures with nucleic acid. This is an increase of 

 74 per cent produced by the addition of nucleic acid to the line 

 of cultures containing no nitrate. 



The results here recorded on the green weight are in full accord 

 with the actual observations made on the plants while growing. 

 For the purpose of record a photograph of this series of cultures 

 was taken after arranging the two sets, with and without nucleic 

 acid, alternately in pairs qf like composition in regard to the 

 mineral salts, phosphate and potash. 



Cultures marked with the same number, for instance 56 and 

 56N have similar fertilizer ratios. The cultures marked with 

 numbers alone have no nucleic acid, the numbers with the letter 

 N have 100 parts per million of nucleic acid. The compositions 

 of the solutions are the same as those in Table I. 



As shown in the figure the plants in each culture containing 

 nucleic acid, no matter what the proportion of potash and phos- 

 phate, is larger than the plants growing in a similar solution 

 without the nucleic acid, the tops in each case being broader 

 and taller. 



Grouih in cultures containing eight parts per million NH3 as nitrate 



Since nucleic acid was very beneficial in cultures containing no 

 nitrate, it is interesting to observe its effect in cultures which 

 contain a small amount of nitrate. Table II gives the result of 

 the effect of nucleic acid on growth in those culture solutions 

 composed of 8 parts per million NH3 as nitrate and varying 

 amounts of potash and phosphate, the total concentration of 

 each solution being 80 parts per million of P2O0 + NH3 + KoO. 

 By comparing the figures in the fifth and sixth columns, it is 

 seen that the growth with nucleic acid is still considerable larger 

 but the difference caused by the nucleic acid is not near so great 

 as in solutions containing no nitrate, presented in Table I. The 

 total green weight of these 10 cultures was, without nucleic acid, 

 25.272 grams, against 31.080 grams in the cultures with nucleic 



