CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE MUSEUM OF 

 COMPARATIVE ZOOLOGY AT HARVARD COLLEGE, UNDER THE DIRECTION 

 OF E. L. MARK. Director. No. 213. 



THE MOVEMENTS OF THE EARTHWORM: A STUDY 

 OF A NEGLECTED FACTOR 1 



SERGIUS MORGULIS 



TWO FIGURES 



In presenting these observations upon the movements of earth- 

 worms and the conclusions to which the results of specially ar- 

 ranged experiments have led me, I shall deal with two distinct 

 problems. The one is, whether the earthworm in locomotion re- 

 acts as a succession of separate segments or as a unit-organism ; 

 the other is, what determines the worm's movement in a definite 

 direction? Strange as it may seem at first glance, a definite solu- 

 tion of the first problem depends to some extent upon the solution 

 of the second. It is, therefore, impossible to treat the problems 

 quite independently. 



Friedlander ('04), who very thoroughly investigated the mech- 

 anism of the earthworm's locomotion, maintains that in the nor- 

 mal creeping of the worm there is no nervous impulse passing from 

 one end of the animal to the other, but that " every segment by 

 its activity furnishes the stimulus that causes the adjacent 

 segment to become active in a similar way; therefore, in quiet 

 normal creeping the earthworm functions not as a unit-indi- 

 vidual, but, so to speak, as a chain of segments" (p. 181). 



This view, as I understand it, is in essence, a subtle analysis 

 of the mechanism of locomotion; Friedlander finds that a certain 

 degree of muscular extension invariably precedes a contraction, 

 and that a segment in the state of contraction exerts sufficient 

 pull upon the next segment to induce a general contraction in 



1 I wish to express my sincerest thanks to Professor G. H. Parker, who spared 

 neither time nor trouble in helping me in this work with deed and criticism. 



