124 



University of California Puhlications in Zoology [Vol. 18 



The very noticeable result of this series of experiments was the 

 great variability in the speed, which seemed to depend on the state of 

 irritability in the worm. 



Another important fact seemed evident from these measurements; 

 namely, the longer the section of nerve measured the slower the rate 

 recorded. 



Time Taken to Travel Over Certain Lengths of Normal and 

 Anesthetized Worms 



Average 



.370 



.452 



'60 



' These figures are calculated from experiment 180, a series different from 

 that in columns 2 and 3. 



The method for making these records was not refined and the 

 times recorded can only be approximations. The table will show that 

 where the length of the portion of the worm measured is increased the 

 time of transmission increases, but not proportionately. The full 

 significance of this fact and its relation to transmission and a new 

 theory of locomotion will be brought out in a later part of this paper. 



In measuring the speed of the impulse through the nerve cord in 

 a section where the muscle had been anesthetized, the electric method 

 of measurement was quite effective. Records of slight movements of 

 the segments just anterior to the inert section were followed by the 

 registration of movements beginning in the part immediately behind 

 this portion. Here again we meet great variability, depending on the 

 state of excitement in the worm. If the etherized section is greatly 

 increased in length the point will eventually be reached when no 

 impulse comes through. Records through more than twenty segments 

 were frequent, but when more than twenty segments were used, failure 

 resulted more often than in fewer than twenty. Measurements were 

 recorded over twenty-eight segments but these seemed to be exceptional 



