NOTE ON THE GALVANOTROPIC RESPONSE OF THE 



EARTHWORM 1 



A. R. MOORE AND F. M. KELLOGG, 

 BIOLOGICAL LABORATORY OF BRYNT MAWR COLLEGE, BRYN MAWR, PA. 



Since Blasius and Schweizer 2 first found that many animals, 

 both aquatic vertebrates and invertebrates, orient themselves 

 characteristically to the electric current, the galvanotropic 

 response has been studied carefully by a number of investigators 

 in paramecia, motile algae, medusa strips and tentacles, certain 

 Crustacea and salamanders. In general it may be stated that 

 under normal conditions, paramecia, motile algse, and pieces of 

 medusa tend to move toward the kathode, while vertebrates and 

 Crustacea which are galvanosensitive, progress toward the anode 

 and avoid the kathode either by turning away from it or by 

 walking backward. Loeb 3 and his collaborators account for the 

 coordinated movements of vertebrates and Crustacea under the 

 influence of the electric current by suggesting that they are due 

 to changes in the tension of associated muscle groups, viz: 

 flexors and extensors. 



It seemed that the earthworm, Lumbricus terrestris, with its 

 simple locomotor system of circular and longitudinal muscles 

 offered favorable material for testing this idea. The following 

 is an account of the response of this animal to the constant elec- 

 tric current, based on a large number of observations made on 

 different individuals at different seasons of the year. It is true 

 that Blasius and Schweizer noted the galvanotropic response of 

 Lumbricus but unfortunately limited their description to the 

 stimulating effects of the "make" shock and the final crawling 

 of the animal to the kathode, consequently omitting mention 

 of the significant intermediary stages due alone to the flow of the 

 constant current. 



In our own experiments, an animal to be tested was put into a 



1 Drawings by Mary Cline. 



2 Blasius and Schweizer, Pflueger's Archlv, Bd. 53, S. 493. 



3 Loeb, J., Pflueger's Archiv, Bd. 66, S. 439. 



