270 
AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
Table ii. The Average Monthly Air Temperature at Pullman, Washington, and Madison, 
Wisconsin, for the Duration of the Cultural Experiments 
Month 
Temperature °F. at Pullman, 
Washington 
Temperature °F. at Madison, 
Wisconsin 
^915 
1916 
1917 
May 
53 
49 
52 
59 
56 
62 
July 
66 
63 
72 
August* 
74 
65 
68 
* The August temperatures are from the first to the fifteenth inclusive. 
Table 12. The Average Monthly Precipitation at Pullman, Washington, and Madison, 
Wisconsin, for the Duration of the Cultural Experiments 
Month 
Rainfall in Inches at Pullman, 
Washington 
Rainfall in Inches at Madison, 
Wisconsin 
1915 
1916 
1917 
May 
2.77 
1.56 
3.33 
June 
0.53 
2.34 
6.47 
July 

0.77 
0.45 
3.10 
August . , 
0.00 
1.24 
2.72 
The important meteorological data for the periods during the growth 
and maturation of the plants are given in tables 10 and 11 and in graphic 
form in figure 2. The climatic differences for the three years, the first two 
at Pullman, Washington, and the last at Madison, Wisconsin, are sum- 
marized as follows: The 1915 growing season was very dry and cool, with 
high temperatures during maturation; the 1916 season was moderately 
dry and cool; the 1917 period was very wet and hot. The light intensity 
during the last year was considerably lower than during the first two 
seasons. 
No attempt is made to correlate the variations in composition with any 
individual factor, for it is impossible to do more than speculate until con- 
trolled experiments have been run to determine the relation of such factors 
as light intensity, air and soil temperature, and humidity on the develop- 
ment and composition of plants. 
Summary 
1. The calcium content of both grain and straw is reduced to about 
10 percent of that of the plants from the controls by reducing the calcium 
in the culture solution to one tenth the quantity present in the complete 
nutrient solution. It is greatly reduced in both grain and straw by a 
similar deficiency in phosphorus or in nitrogen. 
2. The total phosphorus content of the grain is reduced to 46 percent, 
and of the straw to 10 percent, of that in the plants from the controls by 
reducing the phosphate in the culture solution to one tenth of the quantity 
