NORMAL AND ABNORMAL PERMEABILITY 
W. J. V. OSTERHOUT 
Some investigations by the writer on the permeability of protoplasm 
have recently been reviewed by Hober.^ It seems evident that his 
views depend in part on a misunderstanding in regard to the relative 
amount of permeability under normal and abnormal conditions, and 
in part on a misunderstanding of the author's meaning. 
The investigations of the writer show that the permeability of cells 
of Laminaria can be determined by measuring their electrical resistance. 
In sea water the normal permeability remains unaltered for a long time : 
in a solution of NaCl of the same conductivity as the sea water the 
permeability rapidly increases (as shown by the lessened resistance) : 
this increase continues until the tissue is dead. The alkali salts behave 
in general like NaCl. The addition of a definite amount of CaCl^ to 
the NaCl prevents (at least for some time) the increase of permeability 
which would occur in pure NaCl. 
On this Hober comments as follows : " Osterhout schliesst a us diesen 
Versuchen, dass der lebende Protoplast von den lonen der Alkalisalze 
leicht zu durchdringen ist. Aber ich halte diese Folgerung auch hier 
wieder fiir nicht richtig. Vielmehr zeigen die Versuche nur, dass die 
Laminariazellen ein Widerstandsmaximum aufweisen, wenn sie sich 
unter den physiologischten Bedingungen des Aufenthalts in Meer- 
wasser befinden, und dass sie den Ubergang in abnorme Bedingungen 
mit Widerstandssenkung, also mit Permeabilitatsverringerung^ beant- 
worten, vergleichbar der, die auch den Tod begleitet." 
As has been suggested, Hober's views are due, in part at least, to a 
misunderstanding and it seems desirable to indicate briefly wherein 
this lies. 
The writer has laid emphasis on the rapid penetration of pure NaCl 
and similar salts because this penetration was expressly denied by 
Overton and was used by him as one of the chief evidences for the lipoid 
theory of permeability. As is well known Overton reported that 
cells of Spirogyra when plasmolyzed in NaCl did not recover, thus 
showing that the salt did not penetrate. The writer repeated this 
experiment and found that penetration occurred: this conclusion was 
^ Die physikalische Chemie der Zelle und der Gewebe. 4**^ Aufl. 1914, S. 362 ff. 
2 " Permeabilitatssteigerung" is evidently meant. 
93 
