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University of California Publications in Zoology [VOL. 18 



locomotor impulses are not "short relays" depending on a stimulus 

 from each segment, but are capable of running a number of segments 

 with no stimulus from the outside. 



post. 



time in 

 Vs sec. 



ant. 



A B 



Fig. 9. Experiment 190. Continuation of experiment shown in figure 8. At 

 6:20 P.M. the worm had recovered from the effects of the stovaine. Normal 

 coordinated movements are being made (A) and the giant fiber action has 

 returned (-B). Stimulation of the anterior end at the arrow shows a response 

 in the posterior end. 



LIMITS OF TRANSMISSION 



Problem. How far will these locomotor impulses travel in the 

 cord? Can a middle area of sufficient length be anesthetized so that 

 no impulses from the anterior piece can get through to start locomotion 

 in the posterior part? 



Discussion. It was soon discovered that transmission was best 

 shown when it was concerned with few segments and that, as the 

 number of ganglia through which the impulse must pass was increased, 

 the coordination became less and less perfect. No sharp limits could 

 be determined. When the nerve cord was dissected free from muscle, 

 the most severe type of dissection, the transmission seemed to be 

 limited to eight free ganglia. In one case, coordinated movements 

 were obtained when ten ganglia had been freed, but this was unique. 



