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Proceedings of Royal Society of Edinburgh. [sess. 
intrapolar currents. By an arrangement not shown it could be 
thrown either into CD or into C'D'. 
The balancing arrangement was used for the intrapolar currents 
in order to diminish the irregularity in the deflection, which is 
much more troublesome than even in extrapolar experiments. Of 
course, only one nerve was stimulated. 
i 
The circuit of G' was broken by a simple key, whenever the 
extrapolar regions were to be connected with G. The current was 
then passed through CD, compensation completed in the galvano- 
meter circuit, and the stimulation effect read off. After the nerves 
had recovered, the two intrapolar regions were thrown on to G and 
G', the extrapolar being off. The same current was now passed 
again in the same direction, for the game length of time, and the 
stimulation effect again taken. A given number of cells would 
give practically the same current density in CD, whether the alterna- 
tive circuit C'D' was open or closed, since the internal resistance of 
the battery is very small compared with the resistance of the nerves. 
Experiments 8, 9, and 10 (pp. 246, 247) are examples of this method 
as applied to currents near the limiting intensity. An electromotive 
force of about 5 Daniells working through 9 mm. of nerve gives the 
density corresponding to the disappearance of the intrapolar effect. 
This limiting electromotive force will be inversely as the length of 
nerve included in the circuit, if we assume that the specific resistance 
