6i 
THE ELECTRIC CONDUCTIVITY OF 
MAMMAXIAN NERVE 
By R. S. WOODWORTH, Ph.D. 
SENIOR DEMONSTRATOR OF PHYSIOLOGY, AND FORMERLY G. W. GARRETT FELLOW IN THE UNIVERSITY OF LIVERPOOL 
IN continuation of the work of Macdonald 1 on the physical properties of nerve, 
a series of measurements has been performed to determine the electric 
conductivity of the sciatic and ulnar nerves of the cat, and the influence on the 
conductivity and on the weight ot a five minutes' immersion in saline solutions of 
different strengths. It will be recalled that Macdonald found the injury current to 
be increased or decreased in a very definite way by immersion for five minutes in 
solutions of different concentrations. The strength of the injury current obeyed so 
definite a ' concentration law ' as to warrant the conclusion that this current was 
produced by the nerve acting as a concentration cell ; the more concentrated solution 
being in the interior of the nerve, that is to say, in the axis cylinder, and being 
separated from the less concentrated solution or lymph by the partially imper- 
meable membranes surrounding the axis cylinder. In the hope that measurements 
of the conductivity of nerve as affected by immersion in saline solutions would 
further test this conception, the present series of measurements was undertaken. 
The author is indebted to Macdonald for the suggestion of the problem and of 
methods as well as for the loan of apparatus. The latter, and also the procedure, 
were in the main the same as described by Macdonald. 
The sciatic and ulnar nerves were cut from a cat immediately after death, 
and kept in a moist chamber till each was used. Each nerve was cut to a 
length of about 5 cm., its length, resistance, and weight were measured ; it was 
then immersed for five minutes in a solution of potassium chloride of known 
strength, after which its length, resistance, and weight were again measured, 
trom these data the specific conductivity, or conductivity per cubic centimeter, 
before and after immersion, were calculated. 
The moist chamber in which the nerve was placed during the measure- 
ment of resistance, and also the solution in which it was immersed, were main- 
tained as nearly as possible at 1 8° C, and correction was made for the slight 
deviations from this temperature. 
1. Thompson Tares Laboratories Report, 1902, IV, part II, pp. 213-347. 
