1266 
Physiology. — “Resistance, Polarisation and the Psycho-galvanie 
Reflex.” By Prof. 1. K. A. WERTHEIM SALOMONSON. 
(Communicated in the meeting of December 18, 1916). 
The phenomenon commonly known as the psychogalvanic reflex 
(Ps. G. R.) and discovered about the same time by FÉrÉ and by 
TARCHANOFF has’ been the subject of exhaustive research by various 
writers. I shall only mention VrracurH, from whom we have the 
most complete monograph on this subject, and E. D. Wirrsma, who 
in this country made a most careful study of it and showed its 
possibilities in psychiatric diagnosis. 
The reflex consists of a transitory increase of a weak galvanic 
current, passing through the human body, immediately following 
the application of a stimulus to the senses or more generally any 
psychic activity. 
We know but little about the intimate cause of this momentary 
change in the current-strength. Undoubtedly it is possible that a 
reflex action may produce a slight endosomatic, or more probably 
episomatie electromotive force; the method employed by Tarcnanorr, 
who used unpolarisable electrodes and carefully excluded any exoso- 
matic E.M.F. proves this sufficiently. Moreover most authors are 
convinced that a momentary variation of the resistance of the human 
body also occurs. They even consider this the more important part 
of the refiex. On the other hand we must quote GiLDEMEIsTER, who 
as recently as 10 days ago published a series of experiments in which 
he made automatic graphical records of the Ps. G. R. together with 
the resistance of the body for sinusoidal alternating currents. He 
found that the resistance for such currents does not change during 
the Ps. G. R. 
We are still in doubt about the behaviour of E.M. F. of polari- 
sation (the endosomatie and episomatic E. M. F. considered as one) 
and the resistance for direct current during the Ps. G. R. At the 
same time we ought to remember that even the best unpolarisable 
electrodes only partiably prevent episomatic polarisation and do not 
influence endosomatic polarisation at all. 
I have made a few experiments, in the endeavour to get a better 
insight into this much disputed question about resistance and polari- 
sation during the Ps. G. R. 
In order to measure the resistance for direct current of the human 
body during the experiments, I used a method which I first described 
many years ago. The principle, which is closely related to one given 
originally by Oum, includes the use of a comparison resistance and 
