1024 
Journal of Agricultural Research 
Vol. XXX, No. 11 
Table Y. —Reaction changes in solutions in which “fresh” and dried seed were 
soaked. The dried seeds were subjected to a temperature of 100° to 102° C. 
for a period of 48 hours 
NaCl ' 
KCl 
Formic 
aldehyde 
Time 
Lupine 
Corn 
Lupine 
Corn 
Beans 
Fresh 
Dried 
Fresh 
Dried 
Fresh 
Dried 
Fresh 
Dried 
Fresh 
Dried 
Ph 
Ph 
Ph 
Ph 
Ph 
Ph 
Ph 
Ph 
Ph 
Ph 
6.6 
6.6 
6.6 
6.6 
6.5 
6.5 
6.4 
6.5 
3.7 
3.6 
6.1 
6.3 
3.8 
3.6 
6.5 
6.5 
6.1 
6.2 
6.5 
6.3 
5.1 
6.3 
3.8 
3.6 
6.5 
6.3 
5.8 
6.5 
6.3 
4.9 
5.9 
3.9 
3.6 
6.3 
6.3 
5.4 
5.7 
6.3 
6.3 
4 5 
5.5 
4.0 
3.7 
6.3 
6.3 
4.9 
4.9 
6.3 
6.3 
4.1 
4.9 
4 3 
3.9 
6.3 
6.3 
4.6 
4.4 
6.2 
6.3 
4.0 
47 
45 
4.1 
6.3 
6 3 
4.4 
43 
6.3 
4.0 
42 
47 
4.4 
5.9 
6.2 
4.1 
6.1 
3.9 
4.1 
49 
4.8 
5.5 
6.3 
4.1 
4.1 
5.5 
6.1 
3.9 
3.9 
5.0 
49 
4.9 
4.9 
4.9 
5.2 
5.4 
5.3 
4.7 
4.6 
4.7 
46 
i 
A study of this table shows that the 
reaction changes were possibly some¬ 
what slower in the dried seeds but 
that in general the reaction velocity 
did not undergo great changes. It 
might be that because of the drying 
of the seeds, slight chemical changes 
occured in the seed, so that the me¬ 
chanical intake of the ions was re¬ 
tarded; or it might be that, on account 
of the drying, some of the retained 
moisture in the seeds was driven out 
and the moisture content had to be 
replaced to its original amount before 
the seeds were able to absorb the ions 
from the salt solutions and acids. It 
is interesting to note, however, that 
in all cases the final equilibrium was 
established regardless of the previous 
drying. Even in the case of dried 
seeds soaked in a formaldehyde solu¬ 
tion the hvdrogen-ion concentration 
was changed from Ph 3.6 to P H 5.3 
after 2 hours. None of the dried seeds 
germinated, while from 61 to 84 per 
cent of the “fresh” seeds germinated 
after being subjected to immersion in 
salt solutions for 2 hours. 
It is known that when dry seeds 
are placed in moist soil or salt solu¬ 
tions they absorb moisture with great 
power. This absorption is not a 
simple phenomenon but implies forces 
like imbibition, capillarity, surface 
tension, osmotic pressure from in¬ 
ternal salts, and possibly other forces. 
The amount of absorption depends on 
the salt concentration in the soil or 
solution. In previous papers 4 it has 
been shown that there is a difference 
in the absorbing powers of different 
species of seeds, that different salt 
solutions are differently affected, and 
also that there is variation in the 
amounts of salt solutions (in the form 
of ions) taken up by the different 
Loeb 5 has suggested that in am- 
photheric membranes like those in 
the protoplasm of root hairs, and of 
vacuolate cells generally, the op¬ 
posite sides of the membrane may be 
oppositely charged. Many different 
kinds of membranes are semiperme- 
able and the property of all in common 
in that they are colloidal gels. Water 
can penetrate both phases of the 
colloidal gel, but salt molecules at¬ 
tempting to penetrate the membrane 
would be prevented by physical 
phenomena. From the data here pre¬ 
sented, it seems clear that the ions of 
the solutions are rapidly absorbed by 
the seeds, but the material which 
makes up the seeds, and especially 
the seed coats, can not directly be 
compared with the colloidal gel or the 
semipermeable membrane of the cells 
of root hairs. 
A study was therefore conducted to 
determine what part of the seed plays 
the most important role in ion ab- 
< Rudolfs, W. effect of salt solutions having definite osmotic concentration values upon 
absorption by seeds. Soil Sci. 11: 277-293, illus. 1921. 
- EFFECT OF SEEDS UPON HYDROGEN-ION CONCENTRATION OF SOLUTIONS. Bot. GaZ. 74: 215-220. 
1922. 
s Loeb, J. the reversal of the sign of the charge of membranes by hydrogen ions. Jour. 
Gen. Physiol. 2: 577-594, illus. 1920. 
