112 University of California Publications in Zoology [VOL. 18 



Discussion. Under these circumstances the reactions of the par- 

 tially autotomized worms are the same as in etherized ones; creeping 

 anteriorly and posteriorly can be induced by stimulation. If the 

 anterior end is pinned, the posterior part will still act in coordination ; 

 in this case the only possible way for the transmission to take place 

 would be through the nerve cord. Microscopical sections of such cases 

 as these showed that the nerve card was quite normal in structure and 

 still intact. 



Friedlander (1894) laid such stress on the matter of tension, the 

 pull of one part on the next succeeding segment, that the behavior of 

 the worm under these conditions of anesthesia becomes particularly 

 important as bearing on the correctness and completeness of his 

 explanation (fig. 3). 



Fig. 3. An illustration of Friedlander 's experiment which shows the anterior 

 and posterior parts of the worm tied together with a thread. The movement 

 of the anterior piece pulls on the anterior end of the posterior piece and starts 

 the locomotor reactions which are coordinated with those of the anterior half. 



Conclusion. In cases where the tension is eliminated by pinning 

 the worm to a cork on glass, the posterior part can be seen to begin 

 rhythmical movements of contraction coordinated with those of the 

 anterior part. If this anesthetized portion is composed of but few 

 segments, then the coordination is most perfect and the beginning of 

 the movement of the posterior section follows in shorter time than 

 when this portion of the worm includes many segments. It is possible 

 to anesthetize a section of such length that no coordination is carried 

 on and the posterior part lies entirely inert. In Helodrilus trans- 

 mission of impulses was effective through 20 segments, rarely through 

 28, and never through more than 30 segments. 



NERVE FREE PREPARATIONS 



Problem. The fact that the worms perform autotomy and that the 

 anterior and posterior parts are then connected with each other only 

 by a simple nerve bridge and the intestine, suggested the possibility of 

 dissecting away all the connecting muscle between the anterior and 

 posterior parts. Could the nerve cord be dissected free for a distance 

 exposing several ganglia and could locomotor impulses be transmitted 

 through such a cord? 



