MULTIPLE RESPONSE OF NERVE 537 



instantaneously. But when the recovery is once complete, 

 a similar stimulation will not induce a similar immediate 

 response. Instead of this there will be a brief period of 

 hesitation or latency before its initiation. 



Another interesting phenomenon, which I was first able 

 to observe by the help of the highly magnifying Kunchan- 

 graph, was the occurrence of multiple response in nerve 

 under intense stimulation. I was led to this discovery by 

 an investigation which I had undertaken for the demon- 

 stration of the identity of response in animal and vegetable 

 nerves. After showing the extended parallelism which 

 exists between the two, under similar conditions and varia- 

 tions of conditions, as already described, I was desirous of 

 seeing whether a plant nerve could be substituted in certain 

 experiments for the animal nerve. In accordance with this 

 I used the vegetal nerve in. the experiment known as 

 secondary contraction. Here a nerve-and-muscle preparation 

 of frog is taken, and a second piece of frog's nerve is suitably 

 laid, with one end lying upon the end of the other nerve. 

 On excitation of this second detached nerve, say by electric 

 shocks, excitatory electrical variation is found to cause 

 responsive contraction in the muscle of the first preparation. 

 In my own rendering of this experiment I employed, instead 

 of the second piece of frog's nerve, a length of nerve of 

 fern. In order that the experiment should not be open to 

 any objection arising from the escape of stimulating current, 

 I employed a non-electrical form of stimulus. This was 

 done by touching the plant nerve with a strongly heated wire. 

 The terminal muscle would then, under favourable conditions, 

 begin to respond by strong spasmodic contraction. When 

 this had subsided, a new series of tetanic contractions 

 began ; and this was repeated at short intervals, for nearly 

 half an hour. When this series of spasms had come to 

 a stop, I have often succeeded by a fresh application of the 

 hot wire to the vegetal nerve in obtaining a .second series 

 of such repeated responses. It thus appeared that the 

 strongly excited plant nerve gave rise to a series of multiple 



