290 
THOMPSON YATES LABORATORIES REPORT 
the indication of preliminary experiments in choosing the duration of time most 
suitable for the immersion of the nerve in the solutions used. The shorter the time 
the less will be the undesired modification of the internal solution of the nerve. 
It is thus necessary to fix a time not too short for the best replacement attainable of 
the outer solution, and yet as short as possible so as to ward off this antagonistic 
modification. 
EXPERIMENT I 
Sciatic Nerve of Cat 
A piece of Nerve 5 centimetres long 
Value of injury 'current' upon removal ... 15 x io~ 3 Daniell 
After an immersion of 1 hour and 40 minutes in 
9 per cent. NaCl solution ... ... 1 ,, ,, 
After a subsequent immersion of 1 5 minutes in 
tap water ... ... ... 11 „ „ 
After a furthei immersion of 30 minutes in tap water 
(45 minutes in all) ... ... ... 22 „ „ 
The solution of NaCl used was maintained at 17° C. After each immersion the nerve was dried 
in filter paper. The nerve was examined several times during its prolonged immersion in the concen- 
trated NaCl solution, after the first twenty-five minutes, a second twenty-five minutes, a third twenty-five 
minutes, and then ten minutes ; on each occasion the value of the injur}' potential difference (longi- 
tudinal surface to upper cross section) was found equal to - ooi Daniell. 
EXPERIMENT II 
Sciatic Nerve of Cat 
A piece of Nerve 5 centimetres long 
Value of injury 'current' upon removal ... 17 x io -3 Daniell 
After 5 minutes in -45 per cent. NaCl solution 24 „ „ 
After 45 minutes (in all) in '45 ,, ,, 3 ,, „ 
After a subsequent immersion of 20 minutes in tap 
water ... ... ... ... o „ „ 
The data from these experiments give point to the remarks just made. One of 
these experiments shews the effect of immersion in a concentrated solution ten times 
the strength of the isotonic solution ; the other the effect of immersion in a dilute 
solution one-half the strength of the isotonic solution. 
In both cases, prolonged immersion in the solution has reduced the original 
value of the potential difference down to a small fraction. The reduction in the case 
of the nerve immersed in the dilute solution is irreparable by the subsequent immersion 
