July is, 1921 
Assimilation of Nutrient Salts by Corn 
547 
Precipitated calcium carbonate was used in all solutions, since pre¬ 
liminary tests showed that it measurably increased the growth of roots 
in certain incomplete solutions. Ferric tartrate was used as the source 
of iron, previous work having shown this to be an especially available 
form of iron in the presence of calcium carbonate. In all the nutrient 
solutions, except that lacking potassium, the bases were in the following 
proportions by weight: 1 Mg to 4 Ca to 5.3 Na to 14 IC. In the solution 
lacking potassium the proportions were 1 Mg to 4 Ca to 6 Na. 1 
The nutrient solutions, with the exception of iron, were made up 18 
hohrs before they were to be used. Ferric tartrate was added just before 
the solutions were used, since the availability of the iron in the solution 
decreases somewhat with time. 
All the plants grown in the experiments were analyzed, by the usual 
analytical methods, for nitrogen/phosphoric acid, and potash. 2 The 
results reported are, in practically every case, the average of closely 
agreeing duplicate or triplicate determinations. 
In each experiment one lot of plants was grown with all the roots in 
tlie complete nutrient solution, and another lot was grown with all 
the roots in the solution lacking nitrogen, phosphorus, and potassium. 
The normal, or maximum, assimilation of nitrogen, phosphorus, or 
potassium for any experiment was taken as the difference between the 
quantities present in these two lots of plants. The assimilations at¬ 
tained by plants having their roots divided between more or less com¬ 
plete solutions 3 were expressed relative to this maximum or normal 
assimilation. 
In all the experiments 1 corn plant was grown in each double or triple 
flask, and 8 plants were taken as a unit, the units being duplicated for 
each separate treatment. There were, therefore, 16 plants which were 
treated alike in every case. 
EXPERIMENTAL RESULTS 
PLANTS grown with their roots equally divided between 
TWO SOLUTIONS 
Experiment i. —The roots divided between a complete solution and 
a solution lacking two elements. 
Since in this work only nitrogen, phosphorus, and potassium are 
varied, there are evidently only three possible pairs of solutions which 
1 The small amount of calcium resulting from the slight solubility of calcium carbonate was not consid¬ 
ered in calculating these proportions. 
* Nitrogen and potash were determined in the roots as well as in the stalks and leaves, siuce the roots 
could be washed free from nitrates and potash salts. Phosphoric acid, however, was determined only in 
the stalks and leaves, because it seemed probable that some precipitate of calcium or ferric phosphate might 
adhere to the roots, even after thorough washing. 
* The amount ol nitrogen, phosphoric acid, or potash assimilated by these plants was taken as the amount 
present in the plants minus the amount present in the plants grown in the solution lacking nitrogen, phos¬ 
phorus, and potassium. 
