THE INJURY CURRENT OF NERVE 
259 
'bridge ' method, the circuit being so arranged that a current of less than "Oi milli- 
ampere traversed the nerve at the time of measurement. The sensitive galvanometer 
used in the previous sections was also used in these measurements, and the determina- 
tion was always finally made with this, and without a ' shunt.' 
To avoid any error due to the presence of an injury current, the measurement 
was always repeated with the nerve arranged in a reverse direction, so as to cause this 
current to add to and to subtract from the measuring current ; the values given are 
always the mean of two such measurements. 
In each case given the piece of nerve, cut so as to be as near as possible rive 
centimetres in length, was provided with a clean cross section at each end. It was 
arranged rectilinearly between two electrodes and upon a dry ebonite scale, and its 
length was accurately measured when thus in position. Immediately after the measure- 
ment of resistance the weight was accurately ascertained. 
Data from Eleven Experiments 
Experiments 
Resistance in 
ohms 
Length in 
centimetres 
Weight in 
grammes 
Experiment I 
I 7,000 
•287 
II 
14,200 
4-8 
•237 
„ HI 
17,300 
5'° 
■239 
IV 
23,800 
+•9 
■20I 
v 
I 5,900 
4.8 
•255 
„ VI 
I 7,800 
+■8 
•2l6 
„ VII 
23,500 
5'° 
•195 
„ VIII 
I 8,000 
4-0 
■I45 
IX 
20,300 
5'° 
•236 
X 
20,700 
4-5 
"2 IO 
„ XI 
2 6,000 
4-9 
•207 
Average of 1 1 Experiments 
19,500 
+•8 
■22 I 
If, in these experiments, the determination of weight is treated as if it were a 
determination of volume, and the error so introduced is certainly less than five per 
cent., we have all the data necessary to determine the 'specific' conductivity of the 
nerve. The error would of course be eliminated by a correction for the specific 
gravity of the nerve, but this is difficult to obtain, owing to the peculiar behaviour of 
the nerve when immersed in solutions. Failing this determination of the specific 
