COMPARATIVE ELECTRO-PHYSIOLOGY 



normal response. The abnormal response of nerve we found 

 to be due to the joint depression of conductivity and excita- 

 bility, on account of which the positive alone, instead of the 

 true excitatory negative, was exhibited. In experimenting 

 with frog's nerve we saw that abnormal response might, at 

 will, be converted into normal through the intermediate 

 diphasic by appropriately increasing the effective intensity 

 of stimulation. A simple means of effecting this was to 

 bring the stimulator gradually nearer the responding point. 



FIG. 286. Photographic Record of Effect of Tetanisation in Inducing 

 Enhancement of Normal Negative Response in Nerve of Fern 



The first series of responses seen to be enhanced after intervening tetani- 

 sation, T. 



In the response of vegetable nerve effects exactly parallel are 

 to be observed. 



With a given specimen of vegetable nerve, the stimulator 

 had at first been placed at a distance of 2 cm. from the 

 proximal galvanometric contact, and the responses then 

 taken were found to be of the abnormal positive type. The 

 stimulator was now brought nearer, the distance being 

 reduced to I cm., and the next pair of responses is seen to 

 be diphasic, consisting of a positive twitch followed by the 



