194 BOTANICAL GAZETTE [SEPTEMBER 
Certain solutes are believed to have the same, or similar, effects 
upon the hydrones as increase in temperature. For instance, acetic 
acid, and other substances mentioned in this paper as leading to 
supernormal imbibition, may increase the rate of entrance by 
breaking down the inert complex molecules of water. If the 
interpretation of the results of BRowN and Wor LEY is correct, the 
measure of the rate of water intake may be looked upon as a 
measure of the activity of water when in a certain state which 
depends on temperature, or on the presence of certain solutes. 
While this work is of the greatest interest, it is too early to make 
any general applications of their results. 
If the writer understands ArMsTRONG’s application of his 
hydrone theory (3) to semipermeable membranes, the fine particles 
which make up the membrane are assumed to be chemically united 
to hydrone or hydrol, perhaps under the influence of surface force. 
All the intramolecular passageways through the membrane are 
therefore guarded by hydrone elements. When a salt goes into 
solution the solute molecules also are believed to be hydrolated in 
case of non-penetrating solutes. Now if a hydrolated salt presents 
itself for passage through a hydrolated or hydronated membrane, 
the salt is seized and held back by the mutual attraction of the 
hydrolated surfaces of the salt and membrane. If on the other 
hand an unhydrolated salt presents itself to the same membrane 
the hydrolated passageways are indifferent to the salt, and it passes 
through the membrane without the “chemical seizure’ retarding 
its entrance. Selective action would depend upon the salt rather 
than upon the membrane, for an unhydrolated membrane should 
allow all salts to pass providing other physical and chemical con- 
ditions necessary to passage were met. 
The penetrating salts, whether electrolytes or non-electrolytes, 
are conceived to be those which can exist in water solution in unhy- 
drated condition, or which attract water only to a slight extent; 
whereas those which are excluded are those which form hydration 
compounds of considerable stability; and the semipermeability 
depends on the mutual attraction of hydrated salt and hydrated 
membrane. 
It is the writer’s opinion that ArmsTRoNG’s rather fanciful 


