The Journal of 

 Comparative Neurology and Psychology 



Volume XIV 1904 Number 2 



PHYSIOLOGICAL EVIDENCE OF THE FLUIDITY OF 

 THE CONDUCTING SUBSTANCE IN THE 

 PEDAL NERVES OF THE SLUG— ARIOLIMAX 

 COLUMBIANUS. 



By O. P. Jenkins and A. J. Carlson. 



(From the Physiological Laboratory of Le land Stanjord, Jr., University.) 



In measuring the rate of the nervous impulse in the slug 

 Arioliniax cohimbiamis ^ the fact of the remarkable extensibility of 

 the pedal nerves, which were used for the pupose by us, was 

 a matter of constant observation, as it gave us no little trouble 

 in making the determinations. This slug reaches a large size, 

 individuals being frequently met with which, when extended in 

 the act of crawling, are 25 centimeters in length. 



A workable distance of 8 cm. or more of the pedal nerve 

 can be obtained in such slugs. Now this nerve in the unin- 

 jured living animal is extended during its act of crawling and 

 contracted during its time of rest and during these changes it, 

 obviously, remains functional. We found that when the pedal 

 nerve is freed from its ganglia and allowed to contract without 

 hindrance it would shorten to about one-half the length main- 

 tained in it when the animal was fully extended in the act of 

 crawling. In a muscle-nerve preparation made as described in 

 the paper referred to, this nerve could be repeatedly stretched 

 to this extent and allowed to contract and at each of these posi- 

 tions and at intermediate ones, normal contractions were ob- 

 tained. Thus the stretching of the nerve through these limits 



1 Jenkins, O, P. and Carlson, A. J. American Journal of Physiology, 

 1903, Vol. VIII, p. 251-26S. 



