QUANTITATIVE COMPARISONS 
Experimental Procedure 
Non-polarizable electrodes, having been prepared, were placed in position 2*5 
centimetres apart. 
A cat having been killed, a piece of one sciatic nerve, 5 centimetres long, was 
immediately removed. 
The potential difference was measured between the upper cross section and a 
point on the longitudinal surface 2 - 5 centimetres distant. 
The nerve was then immersed in the solution which had been previously 
prepared and brought to a temperature of i8°C. The nerve was lett in this for five 
minutes exactly timed. During the immersion the vessel containing the solution was 
frequently shaken. The quantity of the solution used was always the same, 
200 cc. 
At the end of five minutes the nerve was removed. This was accomplished by 
seizing its lower end, which is always easily identified, in fine pointed forceps. 
The nerve was placed upon a sheet ot filter paper, which was then folded upon 
it. Complete drying was obtained by rolling the nerve and longitudinally com- 
pressing it between finger and thumb in the fold of filter paper. This drying 
operation was repeated three times, a dry place in the filter paper being used each 
time. 
The potential difference was then again measured. 
When the second sciatic nerve of the same animal was used, a routine method 
was followed. As soon as the first nerve had been placed in the prepared solution 
the second was immediately removed, examined, and placed in a separate vessel of 
solution just as the time approached for the final examination of the first nerve. In 
this the examinations and immersions of the two nerves were made to alternate 
and consequently only a small interval of time elapsed between the removal of the 
two nerves. Even this slight difference was not, however, without its consequence 
(for reasons, see previous section), and accordingly in all the experiments quoted such 
nerves are always marked ' (2) ' to distinguish them from the nerves prepared first, 
which are marked '(1).' 
The confidence placed in a single examination of the potential difference between 
the upper cross section and the mid-point of the nerve was the outcome of the experi- 
ments performed in the first section of this paper. In the curves of that section it 
will be noticed that the main variations in the value of the potential difference take 
place in the first two centimetres, and are unimportant at a greater distance. 
