Jenkins and Carlson, Conducting Substance. 91 



of the rate in the nerve in the different states of extension and 

 contraction within the limits indicated. In the pedal nerves of 

 ArioUniax, stretching the nerve within physiological limits in- 

 creases the transmission time for the whole nerve while contrac- 

 tion or shortening of the nerve decreases it, but in each change 

 of length of the nerve the velocity in a unit of length is the 

 same, that is the rate is the same in the two conditions. 



It is obvious that if the change of the length of the nerve 

 was due to the straightening out or the formation of folds and 

 kinks either in the nerve as a whole or in elements in individual 

 nerve fibers the transmission time between two constant points 

 of the nerve would be the same, and the rate would appear 

 greater in the stretched condition as compared to that of the 

 contracted condition. But the fact that the transmission time 

 between any two points increases with the stretching of the 

 nerve seems to show that the stretching is accompanied by act- 

 ual extension of the conducting substance, whatever that may 

 be. And the fact that the actual rate remains the same in the 

 two conditions of the nerve seems to prove that this rearrange- 

 ment of the conducting sUbstance does not change the rate of 

 the conducting process. Furthermore, this rearrangement of 

 the molecules of the conducting substance within the wide limits ■ 

 represented by extending the nerve to twice in length does not 

 appear to effect the functional properties of the nerve either in 

 the above experimental conditions or in the normal conditions 

 of the animal. 



These facts are certainly evidence on the side of the view 

 that the conducting substance in this nerve is in a liquid con- 

 dition or at least in a semi-liquid condition. 



These experiments also confirm measurements of the rate 

 of the nervous impulse in the pedal nerves of Arioliinax report- 

 ed by us in which the average rate was found to be 40 cm. per 

 second. These records show an average rate of 36 cm. per 

 second, the slightly lower figure in the latter case being in all 

 probability due to the greater number of records used from each 

 preparation, as it will be seen from Tables I, II and III that the 

 rate decreases rapidly during the course of an experiment. 



