6 4 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
about one-eighth of the gramme-molecular. This strength of KC1, or 0*93 per cent., 
is thus near to the isotonic solution of nerve, whether judged by weight or by- 
conductivity. 
The ratios of the specific conductivity after immersion to the original 
conductivity are as follows : — 
Sciatic 
Ulnar 
Distilled 
water 
o-8 3 i 
0-766 
1 /40th g 
ram me- 
molecular 
0-847 
o-8u 
1 '20th 
yy ... 
0-872 
0-878 
i/ioth 
?» 
yy 
0948 
0-899 
1 , 8 th 
79 
79 ' " 
0-985 
0-992 
0-15 
99 • •' 
1-033 
I "020 
1 '5th 
99 
... 
1 • 1 1 1 
1-088 
1 /4th 
99 ' * ' 
1-163 
1 -172 
1/2 
yy 
... 
1-529 
1 62 1 
I 
99 
99 ' • • 
2-137 
1-972 
2 
99 
yy 
3'°39 
3"363 
Five minutes' stay in distilled water does not deprive a nerve of all its 
conductivity, but of only about 20 per cent. Now Macdonald 1 concluded, from 
the regularity with which the injury current of nerve obeyed the ' concentration law,' 
after five minutes' immersion in any solution, that this length of immersion sufficed 
to replace the lymph of the nerve sheathes by the solution used, without much 
altering the solution present in the axis cylinders. Adopting this conception, I infer 
that five minutes' stay in distilled water practically abolishes the conductivity of the 
external solution, so that the conductivity that remains belongs to the ' internal 
solution ' in the axis cylinders. I thus infer that about 80 per cent, of the 
normal conductivity of a nerve is furnished by the internal solution. 
This view is confirmed by the effects of other solutions on the conductivity v 
For if the internal solution remains the same after five minutes' immersion in any 
solution of KC1, while the external solution acquires in each case the concentration 
of the solution used, then the internal conductivity would remain constant throughout 
( = 80 per cent, of the normal conductivity of the whole nerve), and the external 
1. Op. at., pp. 292-296. 
