June 1,1925 
Effect of Seeds on Hydrogen-ion Concentration 
1025 
sorption. The seed coats of soy beans 
were carefully removed from the 
cotyledons and both cotyledons and 
coats placed in different acids and salt 
solutions; similar material was placed 
in distilled water. The water was not 
redistilled and was, as usual, slightly 
acid. The figures secured for beans 
soaked in hydrochloric acid are pre¬ 
sented in Table VI. 
Table VI.— Reaction changes in 0.001 
normal HCl and distilled water 
caused by dicotyledons of soy beans 
It can be seen at once that the coty¬ 
ledons of the soy beans were more 
powerful in absorbing ions from this 
acid than were the coats. No re¬ 
action changes seemed to occur in 
distilled water. The dicotyledons of 
soy beans contain saturated acids, great 
amounts of oil and masses of protein. 
Since proteins are amphotheric, it 
seems justifiable to assume that the 
proteins are mainly active in ion 
absorption. It is well known that 
carbohydrates do not behave in a way 
similar to proteins. However, the 
influence of corn seed coats, the car¬ 
bohydrates of the inner cells of the 
seeds., and pure starch upon the 
reaction changes of magnesium sul¬ 
phate solutions as compared with 
redistilled water was determined. Table 
VII gives the condensed data secured 
in one series of trials. 
The reaction changes brought about 
by the seed coats in the MgS0 4 solu¬ 
tions were similar to the reaction 
changes caused by the whole seeds, 
while the reaction changes caused by 
the endosperm of the corn seeds (car¬ 
bohydrates mainly) were negligible. 
As could be expected, no changes 
occurred in the salt solutions or water 
with pure starch. The protein content 
of the corn seed coat seemed, there¬ 
fore, responsible for the changes of 
hydrogen-ion concentrations. 
It may perhaps be said that the 
characteristic external acidity which 
each species of seeds tends to preserve 
seems to be determined by the chemical 
properties of its chief constituent pro¬ 
tein. The fact that a given species of 
seeds causes (and maintains in weak 
solutions) a certain equilibrium of 
hydrogen-ion concentration might pos¬ 
sibly throw some light upon the ques¬ 
tion why certain plants are better able 
to withstand an acid or alkaline soil 
than others. If for instance a certain 
species of seeds maintains a character¬ 
istic P H point 4.0, the seedling possibly 
would be able to survive in a more acid 
soil than a species of seeds with a 
characteristic P H point of 5.8. How¬ 
ever, a certain equilibrium caused by 
the seeds in the surrounding nutrient 
or soil solution does not necessarily 
mean that the growing plant causes a 
similar reaction, because the watery 
protein materials in the growing plant 
cell might have different characteris¬ 
tic Ph points. Moreover, the grow¬ 
ing plant seems to be able to adjust 
or regulate internal changes readily. 
This is shown by Bauer and Haas, 6 who 
Table VII.— Influence of corn seed coats and starch upon the reaction of changes 
of magnesium sulphate as compared with distilled water 
