53° BOTANICAL GAZETTE [JUNE 
large quantity as compared with the acid that the amount changed 
is small in comparison with the total amount, or that the substance - 
formed as a result of the absorption is broken down again almost 
as soon as formed. Such a view of the plasma membrane is held 
by Pautt and Sztcs, who regard the entrance of ions into the cell as 
due to the reversibility of such a reaction between ions and the 
plasma membrane. We feel, however, that more experimental evidence 
is required before such theories can be discussed adequately and with 
profit.” It is extraordinary that anyone could see support for 
Sztcs’s view in that statement. 
Finally, in the title of the paper the term permeability was used 
in its ordinary general sense, and in our opinion the title gave a 
reasonable representation of the contents of the paper, which 
should be its function. 
For the reasons already stated we hold that that large body of 
workers who have included the absorption or exosmosis of dissolved 
substances among the phenomena of permeability are completely 
justified. OsTERHOUT’s statements, ‘‘the results obtained by 
these methods have been so largely misinterpreted,’’ and “the 
principal difficulty lies in confusing permeability with absorption” 
seem to be due to his giving to the term permeability an indefinite 
and yet restricted meaning. It is unfortunate that he should not 
have realized that he and the writers he criticizes use the word 
permeability in a different sense; it is still more unfortunate that 
he should attribute to them his own use of the term permeability, 
and it is particularly regrettable that he should assume they mean 
the same things by ‘‘temperature coefficient of absorption’? and 
“‘temperature coefficient of permeability” (in his sense, not theirs) 
when they carefully avoid such an expression as “‘temperature 
coefficient of permeability” on account of its indefinite meaning. 
OSTERHOUT says that he himself used a method for determining 
the temperature coefficient of permeability which is free from the 
“‘objections”’ just discussed. We may now consider how far this 
statement is justified. He states that “by this method the electrical 
conductivity of living tissue was determined in such a way that it 
may be regarded as a measure of the permeability of the proto- 
plasm.” We propose therefore to discuss OsTERHOUT’S work under 
