THE INJURY CURRENT OF NERVE 
2 33 
Three double sets of observations were taken : — 
(1) The potential differences between points upon the longitudinal surface and the upper 
cross section. 
(2) The potential differences between the same points and the lower cross section. 
(3) A repetition of (1). 
Each double set of observations occupied ten minutes. The total time spent over the three sets 
was thirty minutes ; no interval was allowed between one set and another, and the taking of every 
observation was accurately timed. 
For the sake of simplicity, the description of the geometrical position of each point is always the same 
throughout the whole set of observations. Whether the potential difference is being taken between a point 
and the upper or the lower cross section, the distance of the point from the upper cross section provides it 
with its name. Thus point (1) is always a point distant 1 centimetre from the upper cross section, etc. 
The order in which the figures are given and the arrows drawn alongside of them Jully indicate the ordet in 
which the observations were made. 
The difference between the two cross sections was only once measured, and the upper cross section was found 
to be negative to the lower by "00422 volt, the relative time at which this measurement was taken will 
be seen from the list of observations in which it is recorded. // was measured at the mean time of the whole 
set of observations. Point (8) is marked with an asterisk to emphasize the measurement taken between 
the two cross sections, and the same plan has been followed in all the other experiments of this section. 
There was no potential difference between the electrodes, and there never is in the experiments given any 
reason to apply a correction for such a difference. Differences between electrodes are usually the result 
of a slight difference in the concentration of the zinc sulphate solution in the two tubes, the result of 
pouring zinc sulphate solution into imperfectly dried tubes. This error has been completely avoided by 
the use of very wide U tubes, having a bore of 1*5 centimetres, so that they contain a large volume of 
the solution, and by cleaning them always the night previous to the experiment, and using them dry in 
the morning without resorting to any further cleaning process. 
The nerve was, as in the last experiment and all succeeding ones, laid on an ebonite scale in a large 
moist chamber (25 centimetres long and 25 centimetres broad by 10 centimetres deep), the electrodes 
were freely moveable upon ebonite runners placed in this moist chamber, parallel to and one on 
either side of the scale on which the nerve was placed. The greatest care was taken to secure perfect 
insulation of every piece of apparatus made use of. 
Potential Differences taken from the 
Upper Cross Section 
(0 
(2) 
(3) 
(4) 
(5) 
•01 491 
•01755 
•01795 
•01795 
•01769 
(6) -01769 
(7) -01565 
(8) * -00422 
■°H39 
•OI737 
•01 803 
•01756 
•01 742 
•01756 
•01 53 1 
•0042 2 
Potential Differences taken from the 
Lower Cross Section 
•OO950 
•OI 209 
•OI 2 2.S 
•01 1 88 
•01 1 62 
•01 148 
•00924 
Potential Differences taken from 
the Upper Cross Section 
■00898 
•01307 
•01 1 30 
•01492 
•01 1 56 
•0155; 
•01 135 
•01465 
"0 1 1 20 
•OI4I 2 
•01 135 
•OI399 
•00924 
•01 294 
■OI 2 14 
■OI426 
f 'OI45 2 
•OI4I 2 
•OI399 
•OI399 
•o 1 294 
