1916] SHULL—SOILS II 
moisture content of the seeds and soils at the time the bottles were 
opened expressed the equilibrium relation of that soil moisture 
content. 
Since means are at hand for determining the internal force of the 
seed at practically any moisture content, it is possible to determine 
Fic. 1.—Rotator used in these experiments, with motor and speed reducer. 
from the data the forces of the soils which are in equilibrium with 
those of the seed. 
The principal sources of error lie in the fact that moist soils 
and seeds cannot be handled in ordinary atmospheres without 
some loss by evaporation during the handling, and in the fact that 
hot-air ovens for drying are not as accurate as vacuum driers. 
No claim is made for greater accuracy than these methods will 
permit. Of course, every precaution was taken to reduce errors 
to a minimum, and the work was done with the greatest speed 
and accuracy possible. It is confidently believed that the results 
to be obtained by more refined methods and more expensive 
