THOMPSON YATES LABORATORIES REPORT 
I have shewn previously* that the results of more prolonged immersions in 
solutions of NaOH follow the same law (general statement) as that followed by the 
results of such electrolytes as NaCl, KC1, HC1. The experiments given above are 
the only ones which I have performed with immersions of short duration, and are 
given without exception. If attention is paid to the ratios in the last column, then, 
the first experiment excepted, the experimental results form an excellent series of 
values declining to a complete reversal. If attention is paid to the final differences 
of potential alone then there is no exception, and such a course is justified by the 
data and observations of page 300. Exception or not, the fact of the reversal is 
definite, and is confirmed by repetition. 
The form, therefore, of the 'concentration law' is of the utmost importance. 
Is it to be considered as unfavourably affected by the failure to bring within its limits 
the results of experiments with solutions of '.37 and '19 grammes percent, potassium 
chloride ? Without hesitation one answers that it is not, and this answer is based 
upon evidence already exhibited in this paper. In the first place, consider the curves 
of fig. A, page 292, and the experiments from which they were drawn, which shew the 
anomalous effect of solutions less concentrated than the 'isotonic' solution. The 
same anomaly has undoubtedly here presented itself in this attempt at quantitative 
comparison. 
The evidence of those earlier experiments is, however, decisive in its indication 
that the anomalous variation is secondary to a primary normal variation capable of 
anticipation upon the lines there indicated and now more definitely formulated in the 
'concentration law.' The considerations there advanced in explanation of this 
secondary anomaly may be summarized in the statement — that the decline of the injury 
current is more rapid in solutions below the ' isotonic ' solution in concentration, because the 
diffusion of electrolytes out of the axis cylinders of the nerve is more complete. The decline 
in this case is, as was then shewn, a real one, and is in contrast to the apparent decline 
which is experienced in concentrated solutions. 
It has been previously asserted (page 303) that the final value after immersion 
should be compared, not to the initial value, but to the value as affected by the 
normal decline, and that there is no means of doing this. The necessity for such a 
correction is greater still when it is acknowledged that the experimental modifications 
used are inevitably themselves productive of variations in this rate of decline. 
The error cannot therefore be allowed for, and necessarily limits the possible 
range of experiment : for its mode of action is capable of prediction, but not its 
quantitative value. That the error has been met with in these experiments with 
dilute solutions is a fact to be recognized, and regretted, but in no way can it be 
allowed to detract from the value of the remaining experiments. 
* Preliminary communication, Proceedings Royal Society, vol. 67, p. 322. 
