102 
Haynes.—A Criticism of Beutner s Theory of the 
indications. It is hardly necessary to point out at the present time that no 
membrane which acts merely by restricting solubility can serve to explain 
the differences of permeability which the living cell exhibits. Such a mem¬ 
brane could not maintain differences of concentration 1 on either side of it , and 
if it were permeable to a dilute solution, a concentrated solution would 
penetrate very rapidly. It is therefore no analogue of the plasma mem¬ 
brane, and Beutner’s claim to have rendered a service to electrophysiology 
similar to that rendered by Nernst to electrochemistry would seem to be 
somewhat insecurely founded, even if the physical basis of his theory were 
satisfactory. 
The Current of Injury. 
Beutner concludes his work by an attempt to explain the ‘ current of 
injury’ in apples. He regards this as a consequence of the system 
conducting 
solution 
membrane containing I membrane containing | conducting- 
acid (cuticle) 
a small amount of 
acid (flesh of fruit) 
solution 
KCl 
KCl 
apple- 
apple- 
M/i 
M/50 
skin 
juice 
and he compares this with Cremer’s nitrobenzene system, which is positive 
on the acid side. Beutner states that the outer skin of an apple consists of 
a mixture of fatty acids and higher alcohols, and that the tissue itself con¬ 
tains far less acid, but he does not state whence his information is derived ; 
and on the basis of experiments on uncut apples, in which he found that the 
expressed juice showed no difference of potential against M/50 KC1, he con¬ 
siders himself justified in regarding the hydrogen ion content of the juice as 
without electrochemical effect. This latter proposition can hardly be main¬ 
tained. What Beutner really shows is that the sum of the potentials 
at A, B, and C is zero in the system 
ABC 
KC1 
M/i 
When the ‘ current of injury 5 is in question a different set of phase 
boundaries arises—among them the junction of the waxy layer with the 
cell-walls, which in the writer’s opinion may play an important part, since 
the cell-wall is likely to contain free acid in aqueous solution. Further 
experiments are needed before the phenomenon of the ‘current of injury’ 
in apples can usefully be made the subject of detailed discussion ; it is most 
certainly valueless to attempt to interpret it in terms of a system which 
postulates for the fruit a homogeneous 1 flesh ’. Beutner has rendered a real 
service to physiology by laying stress on the wide range of electrical 
phenomena which is shown by simple diphasic systems. It is unfortunate 
that the value of his work should be diminished by faulty interpretation and 
its significance minimized by an attempt to make it the basis of a general 
1 Cf. Osterhout : Tourn. Gen. Physiol., v. 225, 1922 
