VALUE OF CERTAIN NUTRITIVE ELEMENTS 
Although the ratio of dry weight of grain to dry weight of straw 
during the three consecutive years varies widely as shown in table 7, 
yet the effect upon this ratio of a deficiency in any particular nutritive 
element of the culture solution is similar throughout the three years. 
The tendency of plants to fruit normally even when their vegetative 
development is very greatly disturbed is brought out strikingly in the 
results presented in table 7. Plants grown in magnesium- or in 
calcium-deficient solutions, provided their vegetative growth is not 
abnormal, produce an abundance of straw and a relatively small 
amount of grain. As shown by the weights of the individual kernels 
in the last four columns of table 7, the grain produced in such solutions 
is very light. Plants grown in solutions deficient in potassium, 
phosphorus, or nitrogen, on the other hand, produce a higher ratio of 
grain to straw, and their kernels are very much heavier than those of 
plants grown in normal solutions. 
Hellriegel and Wilfarth (1888) report that the production of total 
dry matter and grain are greatly decreased when either potassium, 
phosphorus, or nitrogen is deficient. Their data show further that the 
ratio of grain to straw and the weights of the individual kernels of 
plants grown in solutions deficient in phosphorus or nitrogen are higher 
than those of plants grown in normal solutions. They record, how- 
ever, a marked decrease in the ratio of grain to straw and in the 
weight of the individual kernels in plants grown in solutions deficient 
in potassium. My own results are at variance with those of some of 
these experiments, as is shown by the effects of a deficiency in potas- 
sium upon the ratio of grain to straw and upon the weight of individual 
kernels. The data presented in table 7 show that plants grown in 
solutions deficient in potassium have the highest ratio of grain to 
straw and that they bear kernels considerably heavier than those of 
plants grown in normal solutions. 
The seasonal variation in the ratio of grain to straw may be partially 
explained by climatic differences under which the plants were grown 
for the three seasons. These variations will be discussed in a later 
paper. 
The Relation between Nutrients and Water Requirement 
It has long been known that there exists normally a fairly definite 
ratio between transpiration and growth, and that total transpiration 
