136 University of California Publications in Zoology [ VOL - 18 



INTRODUCTION 



In the analysis of the locomotion of the earthworm Friedlander 

 (1894) showed that worms made well co-ordinated movements even 

 after considerable portions of their nerve cords had been removed. 

 He concluded that the nervous system served simply as a medium for 

 very short relayed reflexes and played a secondary part in locomotion. 

 Biedermann (1904) extended this idea by showing that stimuli could 

 run long distances in the cord, and in my recent paper (1918) I was 

 able to show something concerning the limits of this transmission and 

 also the rate at which such impulses travel in the cord when not 

 reinforced from without. 



Straub (1900) claimed that the spontaneous contractions of short 

 sections of earthworm were due to inherent qualities of the muscle ; 

 at least they were not due to the nervous system present. My own 

 experiments seemed to show a contrary result, and in all cases rhythmic 

 movements were only in pieces containing nerve cord. 



The results of these experiments just cited were obtained on worms 

 from which the nerve cord had been entirely taken away. It occurred 

 to me, therefore, to study the effects of regenerating nerve cord on 

 locomotor movements. It is well known that the nerves do not all 

 regenerate in the same time, and this, then, would give me some clue 

 as to which fibers carried locomotor responses and which the end to 

 end collapsing movements. Friedlander (1894) suggested that the 

 quick jerks which take the animal back into its burrow were due to 

 impulses carried by the giant fibers. This has been accepted as most 

 probable, but has not been demonstrated. If, then, a regeneration of 

 the nerve cord would give a differential healing, it would be probable 

 that the giant fibers would unite sooner or later than the transmission 

 nerves, and we would have some definite proof for Friedlander 's 

 contention. 



The effects of simple transverse sections of the ventral cord were 

 studied and later short portions of the cord were removed. Drugs, 

 such as stovaine, were also tested, because they have the effect of 

 "blocking" the nerve cord, which is practically the same as removal 

 of ganglia for a brief time. Drugs have the added advantage of losing 

 their effect quickly, and so the changes in nerve reactions during 

 development and recovery from the anesthesia could be watched. 



