324 
AMERICAN JOURNAL OF BOTANY 
[Vol. 9, 
piring plants under the various conditions under which the plants were 
grown. When the ash content is expressed as percentage of green weight, 
the variation is from 12 to 22 percent between the high- and low- transpiring 
plants. 
Table 7. Comparison of the Average Percentage of Ash in Tops, Roots, and Total Plants 
(Averages of cultures in tables 5 and 6) 
Percentage of Ash Based upon Dry Weights 
Set of Cultures 
Percentage of Ash 
in Tops 
Percentage of Ash 
in Roots 
Percentage of Ash 
in Plants 
Cone, solution in light 
Dilute solution in light 
Dilute solution in shade 
20.27 ± .031 
19.70 ± .015 
19.56 ± .035 
24.17 ± .046 
20.51 ± .026 
17.21 ± .060 
20.84 ± -028 
19.83 ± .013 
19.30 ± .029 
Percentage of Ash Based upon Green Weights 
Set of Cultures 
Percentage of Ash 
in Tops 
Percentage of Ash 
in Roots 
Percentage of Ash 
in Plants 
Cone, solution in light 
Dilute solution in light 
Dilute solution in shade 
2.72 ± .056 
2.16 ± .043 
1.80 ± .038 
1. 16 ± .038 
1.02 ± .039 
0.51 ± .019 
2.20 ± .034 
1.82 ± .030 
1.43 ± .033 
Those who maintain that the salts enter and move within the plant with 
the water might say that, under conditions of low transpiration especially, 
a dilute solution entering a plant is not sufficient to supply all the salts that 
it needs, and that therefore it absorbs additional salts from the solution in 
which it grows to supply its needs. On the other hand, the plant which 
transpires freely would absorb large quantities of solution in which are 
taken up all the salts needed by the plant. Under such conditions low- 
and high-transpiring plants might have the same ash content. Needless to 
say, such a teleological explanation is worthless. 
Table 8 was prepared to determine whether the salts available in the 
solutions in which the plants were grown might limit the amounts entering 
the plants under any of the conditions under which the plants were grown. 
The first column gives the concentration of Knop's solution used. The 
second column gives the total water absorbed per culture. The third col- 
umn gives the total salts absorbed as determined by the ash found. ^ The 
fourth column gives the ash equivalent of the solution,^ which indicates 
^ The initial ash content of the barley grains was so small that it was not subtracted 
from the total ash found in order to get the total ash absorbed. Four lots of 100 uniform 
barley grains each were analyzed for total ash content. The following data are given in 
average values per single grain: Dry weight, 0.0251 g. Ash weight, 0.00067 g. Percent- 
age of ash, 2.68. 
^ The term "ash equivalent of solution" is an arbitrary phrase here employed for 
designating the number of grams of total salts (NO3 excepted) which are present in a 
volume of solution which is equal to the volume of water transpired per culture. 
