Potassium to Growth in Plants. 
205 
absence of potassium was one-fifth that of the plants growing in the 
presence of this element, figures which are very similar to those obtained 
with wheat. The growth of the roots relatively to the tops was greater in 
the plants growing in the full nutritive solution than in those growing in the 
absence of potassium, a slight stunting of the root system being therefore 
produced in the absence of potassium, as in the case of wheat. 
The distribution of the potassium in the plants is shown in Table XVII. 
It will be noticed that in the water culture experiment the corn growing in 
the absence of potassium obtained less than 1 mg. per plant of potassium 
from the solution. Nevertheless we still find that the relative distribution of 
the element per gramme of dry matter formed is practically the same whether 
the plant is grown in a full nutritive solution or in the potassium-free 
solution. The amount of potassium utilized per gramme of dry matter formed 
Table XVII. Amount of and distribution of potassium in Early pedigree 
Dent field Corn grown 32 days in water cultures free from and 
containing potassium. 
Nu f) i tive solution 
used. 
No. of 
plants. 
A mount of potassium 
in 
Tops. 
Roots • 
Entire 
plants. 
Potassium 
utilized per 
gramme of dry 
matter 
formed. 
Tops. Roots. 
Ratio of 
potas- 
sium 
content 
of tops 
to 
roots. 
Total 
potas- Pvtassmm 
sium absorbed 
utilized from the 
per nutritive 
gramme solution 
of dry by one 
matter plant, 
formed. 
Mg. Mg. Mg. 
Mg. Mg. 
Mg. Mg. 
Mg. 
Nutritive solution F 12 
Nutritive solution F, 12 
less potassium. 
726.90 310-40 1037.30 68.21 70.35 
15.10 4.90 20.0 6.95 6.22 
0.96 
in 
68-8 
6.7 
§ 5-59 
0-82 
is 0-0688 grm. in the full nutritive solution, and 0-0067 grm. in the solution 
less potassium, figures which agree with those obtained for wheat and corn 
(see Experiments 1, 2, and 3). 
Experiment 5. In this experiment Japanese buckwheat was grown in 
water culture, solution F being used, as in Experiment 4, with and without 
the addition of potassium. An analysis of two samples of seeds containing 
respectively five hundred and eight hundred specimens showed that the 
mean potassium content of a single seed was 0-06 mg. The buckwheat was 
therefore much poorer in potassium than either the wheat or corn. Four 
plants were grown in each jar, and four jars were used for both the full 
nutritive and nutritive less potassium solutions. The seeds after two days 
in the germinator had grown sufficiently to be transferred to the culture 
solutions, the combined length of root and hypocotyl being about 2 cm. 
long, but the seed-coats had not been shed. Twenty-one days after the 
seedlings had been placed in culture the experiment was closed. At this 
