144 RESPONSE IN THE LIVING AND NON-LIVING 
was found to be abolished. The depression produced is 
so great and passes in so deep that I have often failed to 
revive the response, even after rubbing the wire with 
emery paper, by which the molecular layer on the sur- 
face must have been removed. 
We have seen in the molecular model (fig. 62, d, @) 
how the attainment of maximum is delayed, the re- 
sponse diminished, and the recovery prolonged or 
arrested by increase of friction or reduction of mole- 
cular mobility. 
It would appear as if the reagents which act as 
poisons produced some kind of molecular arrest. The 
following records seem to lend support to this view. 
If the oxalic acid is applied in large quantities, the 
abolition of response is complete. But on carefully 
adding just the proper amount I find that the first 
stimulus evokes a responsive electric twitch, which is 
less than the normal, and the period of recovery is 
very much prolonged from the normal one minute be- 
fore, to five minutes after, the application of the reagent 
(fig. 93,a). In another record the arrest 1s more pro- 
nounced, i.e. there is now no recovery (fig. 93, 4). Note 
also that the maximum is attained much later. Stimuli 
applied after the arrest produce no effect, as if the 
molecular mechanism became, as it were, clogged or 
locked up. 
In connection with this it is interesting to note that 
the effect of veratrine poison on muscle is somewhat 
similar. This reagent not only diminishes the excita- 
bility, but causes a very great prolongation of the 
period of recovery. 
