THE INJURY CURRENT OF NERVE 
235 
We have in the figures of this experiment the means of contrasting the distribu- 
tion of potential on the nerve at the same moment of time as found by comparison 
with the upper and the lower cross section, and that also at a moment of time when 
the potential difference between these two cross sections was observed (-0042 volt). 
Potential Differences 
to upper 
Potential Differences 
to lower 
Arithmetical Differences 
(I) 
•01 362 
•OO924 
•OO438 
W 
•01602 
•01 169 
•OO433 
(3) 
•0165 1 
•01 192 
•OO459 
(+) 
•01 606 
•01 1 6 I 
•OO445 
(5) 
■01580 
•01 141 
•OO449 
(6) 
■01 580 
•01 141 
•OO449 
(7) 
•1 1420 
•OO924 
•OO496 
The two curves drawn from these numbers are given in fig. 3, and it is obvious, 
both in the figure and in the numbers given above, that the curves are parallel and 
reproduce at a different level every minute phase. Further, the difference of level 
between the two curves -004 volt (approx.) is almost exactly the difference found at 
that moment of time between the two cross sections. If the mill of observations out 
of which this similarity has been evolved is considered, it will serve to establish con- 
fidence in the meaning of every curve taken in this routine fashion. The difficulties 
to contend with are found not only in the fall of level with lapse of time, but also, 
as more curves drawn from the numbers given above would show, an alteration in 
the form of the top of the curve. The alteration in form is, however, as regular as the 
fall of level, and, like it, may have a meaning which will repay investigation ; it is 
most clearly appreciable in the cases of nerves removed from animals dead some hours 
(when the surface of the nerve is in a peculiar condition, which is subsequently dis- 
cussed) ; in the case of freshly removed nerves from recently killed animals it is, as 
in this case, only slight. 
Summary 
In general the points which one would like to emphasize in the data of this 
experiment are : — 
(a) That, as Du Bois Reymond noted, the 'equatorial' point, or highest point 
of the curve, does not correspond with the geometrical centre of the nerve. 
(b) That there is a difference between the two cross sections ; but that in this 
case, although by no means in all cases, the highest maximum of the curve is nearer 
to the more negative cross section. 
