108 U^iiversity of California Publications in Zoology [Vol. 18 



lation of the middle area results in a constriction, due to the contrac- 

 tion of the circular muscles with no reflex to the longitudinal muscles. 

 In recovery from the ether treatment the longitudinal muscles recover 

 and reassume normal functions first and the circular some minutes 

 later. In creeping movements the middle section shows that the 

 longitudinal muscles recover their nervous connection first, for they 

 begin to contract in coordination with the anterior part, some time 

 before the circular muscles begin any active participation in the 

 general movement. This condition is due no doubt to the fact that 

 the longitudinal muscles lie deeper than the circulars and so are less 

 affected by the anesthesia. In addition to this the position of the 

 longitudinal muscle is closer to the general blood supply, which would 

 be advantageous in the removal of waste products and the bringing 

 in of new materials. 



THE PROBLEM 



The problem then suggests itself : how is this transmission through 

 a number of segments accomplished? (1) Does Biedermann's dis- 

 covery necessitate the existence of long fiber tracts in the cord? or, 

 (2) Can it be explained on present knowledge of the neurones? (3) 

 Are there any limits to the transmission through anesthetized areas? 

 (4) Can the speed of such impulses be measured, and how do they 

 compare with the speed of nerve impulses in other annelids? 



ACKNOWLEDGMENTS 



The greater part of the experimental work was done at Harvard 

 University during the year 1914-1915, under the general direction 

 of Dr. G. H. Parker, to whom I am greatly indebted for his very 

 kindly interest and his many suggestions. Later the work of bringing 

 together the results of the experimentation was done at the LTniversity 

 of California. I wish to acknowledge and express my appreciation 

 for the helpful criticism and advice of Dr. S. S. Maxwell, of the 

 Department of Physiology, and to Dr. C. A. Kofoid, of the Depart- 

 ment of Zoology, for the general supervision of the work and the 

 revision of this paper. 



EXPERIMENTS WITH ETHERIZED WORMS 



Problem. — Will it be possible to get transmission of locomotor 

 impulses through an anesthetized area in both directions, from anterior 

 to posterior and also from posterior to anterior? 



