268 
AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
crops grown in the field or in artificial culture. In artificial cultures, 
however, it is possible to alter the growth and maturation of the plant 
much more by the deficient nutrients than by climatic factors; therefore, 
it is reasonable to suppose that the deficient nutrient may have as much 
influence upon the composition as the climatic variations. This is not, 
however, minimizing the effect of climate, and such environmental factors 
must be taken into consideration in all studies of this sort whether they 
be field or culture experiments. 
The analytical data previously discussed in connection with nutrition, 
when studied from another angle, that of the relation of climate and geo- 
graphic location to composition, show how closely the influences of these 
various factors are interrelated. The combination of temperature, humid- 
ity, and other climatic conditions greatly influenced the composition of the 
plants except when the reduction of certain essential nutritive elements 
became the predominant factor in controlling plant development. Under 
these conditions, variations due to other environing factors were outweighed 
by the deficient nutritive element. 
Table 9. The Average Composition of Plants grown under Different Climatic Conditions 
Composition of Plants in Percentage 
Based on Dry Weight 
Pullman, Washington Madison, Wisconsin 
1915 
1916 
1917 
Average composition from all cultures 
CaO content of grain 
P2O5 content of grain 
CaO content of straw 
P2O5 content of straw 
Composition of check plants 
CaO content of grain '. 
P2O5 content of grain 
CaO content of straw 
P2O5 content of straw 
Composition of plants grown in Ca-deficient solution 
CaO content of grain 
CaO content of straw 
Composition of plants grown in P-deficient solution 
P2O5 content of grain 
P2O5 content of straw 
0.231 
0.679 
1.932 
0-383 
.0.317 
2.315 
0.673 
0.309 
0.042 
0.520 
0.472 
0.092 
0.305 
0.976 
1.294 
0.646 
0.405 
2.176 
1.047 
0.734 
0,061 
0.220 
0.732 
0.060 
0.960 
1-570 
2.416 
0.915 
1.360 
4.850 
1.900 
0.832 
0.180 
0.485 
0.552 
0.051 
The analysis of plants grown in 191 5 and in 191 6 at Pullman, Washington, 
show in general a smaller accumulation of both calcium and phosphorus 
than in the last year, 191 7, in which the plants were grown at Madison, 
Wisconsin. The phosphorus content of both grain and straw of plants 
grown in the complete nutrient solution and in the solutions with one nutri- 
tive element in each case reduced to one tenth that in the control solution, 
with the exception of the phosphorus-deficient solution, show consistent 
variations for the three years. With few exceptions, the phosphorus 
content is highest in the 1917 samples and lowest in the 1915 samples. 
