Page:Collected Physical Papers.djvu/323

Rh The following photographic records seem to lend support to this view. If the oxalic acid be applied in large

quantities, the abolition of response is complete; but on carefully applying just the proper amount, I find that the stimulus evokes a responsive electric variation which is less than the normal, and the period of recovery is very much prolonged from the normal 1 minute before to 5 minutes after the application of the reagent. In the lower record (fig. 83) the normal response and recovery is seen in the left record. After the application of oxalic acid the record to the right shows a pronounced arrest, i.e., there is now no recovery. Note also that the maximum is attained much later. Stimuli applied after the arrest produce no effect, as if the molecular mechanism had become locked up.