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Walter Stiles 
A powerful argument against this hypothesis, as against the vis¬ 
cosity hypothesis of Spaeth, which it may indeed be regarded as 
including, is that actually such changes in the relative quantities 
of water in disperse phase and dispersion medium do not appear to 
produce any very great change in the rate of diffusion of substances 
through a colloidal system. What appears to be essentially a modi¬ 
fication and elaboration of this hypothesis will be mentioned at the 
end of this chapter under the head of electrical theories. 
Trondle’s Theory of Protoplasmic Irritation 
It has already been noted that from data obtained by a deplasmo- 
lytic method Trondle concluded that the rate of intake of a salt is 
at first independent of the concentration of the salt, and that after 
about the first ten minutes of exposure to the salt the rate of intake 
falls off according to a logarithmic relation. From this Trondle con¬ 
cludes that salt intake takes place by the salt irritating the proto¬ 
plasm which responds by conveying the salt into the vacuole. After 
the first ten minutes the protoplasm exhibits fatigue, and salt intake 
falls off according to Weber’s law. 
Trondle (1920) considered that he had obtained confirmatory 
evidence of the correctness of this theory from the fact that if cells 
are treated with a dilute solution of a narcotic before immersion in 
the salt solution, the intake of the salt is retarded or even completely 
inhibited. The narcotic is supposed to prevent the participation of 
the protoplasm in the absorption process and in consequence the salt 
is not taken up. On the other hand, when the protoplasm is rendered 
inactive by preliminary treatment with dilute acid (o-oi N oxalic 
acid or 0-005 N hydrochloric acid) for five minutes, according to 
Trondle the intake of salt is then proportional to the concentration 
of the salt, thus obeying Fick’s law, although his figures do not appear 
to support this assumed relation. 
In an earlier chapter reasons have been given for not accepting 
the conclusions of Trondle with regard to the course of absorption. 
But even if the results were acceptable, the only legitimate conclusion 
that could be drawn from them with regard to the mechanism of salt 
absorption would be that the passage of salt, during the first ten 
minutes, did not take place by simple diffusion in a solvent, so that a 
solution theory of permeability to salts would be inadmissible. To con¬ 
clude that a phenomenon of stimulation is in question simply because 
after ten minutes the intake of salt falls off with time according to 
