490 STUDIES IN GENERAL PHYSIOLOGY 
in a liquid conductor can also be conceived of only as an excess 
of negative or positive ions on the surface of the solution. 
It seems to me that Ostwald’s assumption is a necessary one, 
and, corresponding with this, I believe that when we assume 
a distribution of electricities in a nerve-muscle preparation, 
as shown in Fig. 138, a definite number of positive ions are 
distributed over the surface of the right half of the prepa- 
ration, and an equal number of negative ions over the sur- 
face of the left half of the preparation. The lines of force 
which go out from the spheres of the spark discharge to the 
preparation can be imagined as the connecting lines between 
the centers of polarized elements. These connecting lines 
would therefore end at the surface of muscle preparations in 
the ions. As soon as the charge disappears from the 
spheres of the discharger, the excess of positive ions on the 
right side of the preparation and the excess of negative ions 
on the left side of the muscle preparation can no longer 
remain separated, and a migration of the ions—a current— 
must occur in the nerves. In this case (in consequence of 
the semi-permeability of certain elements in the preparation ?) 
a collection of ions must occur at certain points in the 
preparation. The ions are converted into atoms and so 
bring about chemical effects either directly or indirectly; 
these chemical effects bring about the contractions which 
we notice during the passage of the spark.’ One can readily 
understand in this way also why the oscillatory nature of 
the discharge is of no importance in the physiological effects 
produced, as the latter are dependent solely upon the migra- 
tion of ions. If our theory is correct, it is therefore to be 
expected that the experiments which have been described 
can also be made successfully, when it is possible to do away 
with the oscillatory character of the discharge entirely. 
1I am now inclined to believe that no transformation of ions into atoms occurs 
in this case, and that the mere change in the concentration of ions at the surface of 
the semipermeable membranes suffices for the result. This harmonizes with a view 
expressed since by Nernst. [1903] 
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