THE INJURY CURRENT OF NERVE 
2 93 
The curves in figure A have been obtained in the following manner. In 
each experiment the original potential difference determined immediately after 
removal of the nerve from the body is treated as unity, and all the modifications 
obtained by the effect of immersion in the solution are expressed in terms of this. 
Thus taking the data from the three experiments — 
Experiment 
III 
Experiment 
IV 
Experiment 
V 
i % NaCI 
•9 X NaCI 
•6 X NaCI 
Ori 
gina 
1 
1 -ooo 
Or 
ginal 
1 -ooo 
Original 
I -ooo 
In 
25 
min. 
0.388 
In 
25 min. 
0-786 
In 25 min. 
1 -060 
In 
55 
?) 
0'2 I I 
In 
50 „ 
0-643 
In 50 „ 
1-059 
In 
70 
O-IJO 
In 
75 » 
0-482 
I" 75 » 
0-635 
In 
85 
CI53 
In 
1 00 „ 
0-429 
In 100 ,, 
0-365 
In 
100 
CI53 
In 125 „ 
0-115 
The curves serve to shew the orderly fashion in which solutions of different 
concentration modify the injury current, or a better form of statement, perhaps, 
modify the decline of the injury current. The more concentrated the solution, the 
more rapid and complete the apparent decline ; the more dilute the less rapid, so 
that the most dilute solutions temporarily enhance the value of the injury current. 
As will be seen from the curves, this statement is unexceptionable when the 
early portion of the curves is considered. In this portion it is realized that the con- 
centration limits — of pure water on one side and saturated solution on the other — are 
associated with the extremes of effect produced, increase of the injury currrent on one 
side and elimination on the other. Between the limits of concentration the effect is 
dependent upon the concentration, the graduated effect being only adequately described 
by taking the effect of one of these limits of concentration — pure water — as the 
maximum, and describing the remainder as the effects of solutions more concentrated 
than this. 
It is only when the later portions of the curves is considered that the isotonic 
solution demands attention as the solution in which the injury current normally 
declines ; separating more concentrated solutions which continue to follow the course 
described throughout the whole time of the experiment from less concentrated 
solutions, which adopt a new and paradoxical course. 
The later action of these less concentrated solutions is quite characteristic, and 
in direct opposition to their earlier effects. For they are seen secondarily to cause a 
L 
