9 ° 
Journal of Agricultural Research. 
Vol. IX, No. 3 
It was expected that plants whose growth was restricted by having a 
portion of the roots present in the incomplete solution would show an 
increased absorption of elements present in both the incomplete and 
complete solutions. The results did not justify the expectation, except 
in the case of plants partially supplied with potassium. In Experi¬ 
ments I, II, III, and IV the partial-nitrogen, plants contained practi¬ 
cally the same percentages of phosphoric acid as plants completely 
supplied with nitrogen. In Experiments V and VI the partial-phos¬ 
phorous plants contained about the same percentages of nitrogen as the 
complete-phosphorous plants. In Experiments VII and VIII the partial- 
potassium plants contained considerably more sodium than the complete- 
potassium plants. And in Experiments IX and X the partial-iron 
plants contained practically the same percentages of nitrogen and 
phosphoric acid as the complete-iron plants. 
It will be noted that, in all the experiments with nitrogen or phos¬ 
phorus, plants with part of their roots in the complete solution had a 
considerably greater ratio of roots to tops than plants with all their 
roots in the complete solution. It might be thought that this was due to 
the incomplete solution furnishing a better medium for growth, aside 
from nutritive effects, than the complete solution. A calculation of the 
average weights of individual roots in the two solutions shows this as¬ 
sumption to be incorrect and suggests that the increased ratio of roots 
to tops of the partial plants was due to an adaptation of the plant under 
the stimulus of a deficiency of the element. The calculations show that, 
with plants partially supplied with nitrogen or phosphorus, the average 
weight of roots in the nitrogen- or phosphorus-free solution was slightly 
less in nearly every case than the weight of roots in the complete solu¬ 
tion. Also the average weight of roots in the complete solution of plants 
with part of their roots in the complete solution was slightly greater 
than the weight of roots of plants with all their roots in the complete 
solution. 
In experiments where potash or iron was the lacking element the 
plants with part of their roots in the complete solution did not have 
an appreciably different ratio of roots to tops from plants with all their 
roots in the complete solution. This was probably due to the fact 
that rice does not so readily respond, by greater root growth, to a certain 
deficiency of these elements. As the plants receiving absolutely no 
potassium or iron had a markedly increased ratio of roots to tops, it is 
apparent that the difference in the response to a lack of nitrogen and 
phosphorus or potassium and iron is chiefly one of degree. 
DISCUSSION OF RESULTS 
The two chief facts brought out in the preceding cultural tests are (i) 
that the fewer roots supplied with an ion the greater is the absorption 
of the ion per gram of roots, and (2) that a plant is unable to attain a 
