THE GALVANOTROPIC RESPONSE OF THE EARTHWORM. 133 



the worm began to orient itself and in a few seconds the an- 

 terior and posterior ends were directed toward the kathode, so 

 that the animal took the form of a U with the concave side 

 toward the kathode (Fig. i). In this situation it continued to 

 make writhing and progressive movements, and therefore the 

 figure varied somewhat from time to time. If, by reason of 

 excessive movements, any part of the worm showed anodal curva- 

 ture, the latter was instantly corrected by contraction of the 

 muscles on the kathodal side. Because of the anterior end of the 

 worm being always the more vigorous in its movements, the ani- 

 mal ultimately succeeded, as a rule, in crawling to the kathode. 



FIG. 2. 



If it were cut into pieces 3 to 4 cm. long, these pieces when placed 

 transversely in the trough and subjected to the action of the 

 constant current, continued to orient themselves in the same 

 fashion as an entire worm (Fig. 2) but progressive movements 

 were absent. When the current was reversed, the specimen, 

 either entire or sectioned, immediately responded by turning 

 its ends towards the new kathode. The delicacy of the response 

 was lost in fatigued animals. 



Since the earthworm has but two muscle systems with which 

 to accomplish its locomotion, viz: circular and longitudinal, it is 

 obvious that one-sided movement or bending can be brought 

 about only by unequal contraction of the longitudinal muscles 

 on the two sides. It would seem that this is a case in which an 

 entire animal responds to the electric current in the same fashion 

 as did Bancroft's 1 medusa tentacles and bell strips. Since no 



1 Bancroft, F. W., Journ. Exp. Zool., Vol. I., p 289. 



