1905.] The Action of Ancesthetics on Living Tissues. 269 



to events occurring either at the cut end, or at the longitudinal surface or 

 hoth, the experiments in Series II were undertaken to determine which of 

 these factors predominated. 



The nerve-chamber was divided by a transverse gas-tight partition of 

 modelling wax, so that the anaesthetic could be applied either to the cut end A 

 or to the longitudinal surface B (fig. 2). The figures obtained from the 



potentiometer readings have been plotted out to a scale on the ordinate 

 of which one division = O0001 volt, and on the abscissa one division 

 = 15 seconds. The point at which the anaesthetic was applied was taken as 

 the zero, and the relative heights plotted from this, the values are, therefore, 

 relative and not absolute (fig. 3). The figures under the middle part of 

 each curve indicate the percentage of CHCI3 vapour, as measured by Waller's 

 densimetric method.* The vapour was contained in a bag of gold-beaters' 

 skin ; the leakage from this was ascertained to be small during the time 

 taken by an experiment of this kind. Here, as elsewhere in this paper, 

 I have only considered experiments where the results are sufficiently 

 concordant to admit of a consecutive series being employed without having 

 to reject isolated experiments. Any unsuspected errors are, therefore, of a 

 constant magnitude throughout a given series. 

 It will be seen that — 



(1) CHCI3 to cut end of nerve causes an increase in the injury current. 



(2) This increase is roughly proportional to the strength of the CHC1 3 

 vapour up to about 12 per cent., greater concentration then gives no further 

 increase. 



(3) CHClg to longitudinal surface causes a decrease of the injury current. 



Scries II. 



Fig. 2. — Nerve chamber. 



* Waller and Geets, 1 British Medical Journal,' June 20, 1903. 



U 2 



