June, 1922] 
MUENSCHER ABSORPTION OF SALTS 
It is true that the concentration of the solution used in the winter series was 
only one half as great as in the summer series. The question might be 
raised as to whether in this case the dilute solution, rather than shading, 
might cause the increase in water requirement. The following experiment 
shows that this is not the case. 
Dilute-Concentrated Solution Cultures 
Table 6 compares the data of the cultures grown in a concentrated solu- 
tion with similar cultures grown in a dilute soulution under the same illu- 
mination. The plants grown in a dilute solution have slightly higher actual 
green weight, dry weight, and ash weight than those grown in the concen- 
trated solution. It is possible that a concentration of 0.28 percent may 
have been somewhat injurious to barley. The plants grown in a concen- 
trated solution have even a slightly higher water requirement and use a 
greater quantity of water per gram of ash in the winter than the plants 
grown in a dilute solution in the summer. It appears, therefore, that the 
reduced sunlight rather than the reduced concentration of the solution is 
largely responsible for the increased water requirement in the cultures of the 
winter series, even if the actual transpiration is decreased considerably by 
shading. 
Table 6. Relation of Ash Content in Barley Plants to the Amount of Transpiration as 
Affected by a Difference in Concentration of Nutrient Solution. Winter 
Series. Plants Grown 5 Weeks {January ig to February 24, 1921) 
Concentrated Solution 
Dilute Solution 
Tops 
Roots 
Plants 
Tops 
Roots 
Plants 
No. of cultures averaged 
17 
12 
Green weight per culture (grams) 
4.92 
2.5 
7.42 
6.97 
3-01 
9.98 
Dry weight per culture (grams) . 
.662 
.120 
.782 
-765 
.150 
.915 
Total ash content per culture 
(grams) 
•134 
.029 
.163 
.151 
.031 
.182 
Ash content (percentage of green 
weight) 
2.72 
1. 16 
2.20 
2.16 
1.02 
1.82 
Ash content (percentage of dry 
weight) 
20.27 
24.17 
20.84 
19.70 
20.51 
19.83 
Total water transpired (cc.) .... 
431-56 
659.6 
Water used per gram dry matter 
(cc.) 
551-87 
720.87 
Water used per gram ash content 
(cc.) 
2,647.61 
3,624.17 
Table 7 presents the percentages of ash in the tops, roots, and total 
plants expressed as percentages of dry weight and green weight for all cul- 
tures grown under the various conditions of the winter series. When these 
data are compared with the data from the summer series in tables 3 and 4, 
it will be noted that the percentage of ash expressed as percentage of dry 
weight usually varies less than five percent between the high and low trans- 
