324 L - H - HYMAN AND A. W. BELLAMY. 



definite bioelectric currents, such as the current of injury, the cur- 

 rent of action, and particularly the permanent currents which exist 

 along the axes of the simpler organisms, are associated with 

 metabolic differences and probably result from such metabolic dif- 

 ferences. These metabolic differences are chiefly quantitative in 

 nature i.e., differences of rate. 



It further seems probable that these axial differences in the rate 

 of chemical change in organisms are responsible for the phenom- 

 enon of galvanotaxis. Owing to the differences in concentration 

 of ions at different levels, the organism is electrically polarized and 

 hence will be expected to respond in a definite way when placed in 

 an electric current. This matter has already been discussed by the 

 senior author ('i8). 7 The anterior ends of most of the lower and 

 simpler animals are positively charged (int.) ; hence it will be 

 expected that when placed in a current the anterior end will be 

 directed toward the cathode. Such is the case in such organisms. 

 In a few cases, described below, we have found that the anterior 

 end is negatively charged (int.) ; such organisms orient with ante- 

 rior ends toward the anode. In some flatworms, and in annelids 

 generally, both anterior and posterior ends are positively charged 

 (int.) ; such animals bend in a U-shape, with the two ends of the 

 body directed toward the cathode. It thus appears that the in- 

 ternal charge, in many animals at least, determines their galvano- 

 tactic response. A suggestion to this effect was previously made 

 by Coehn and Barratt ('05), but was incomplete, as these authors 

 did not take cognizance of the fact, at that time but recently dis- 

 covered, that there is a graded difference of potential along the 

 axis. 



One of the prevailing theories of galvanotaxis is that adopted 

 by Loeb and discussed by him in his book on forced movements 

 ('18). This theory assumes that the galvanotactic orientation is 

 due to the direct action of the current on ciliary or muscular ele- 

 ments or on the nerve cells that control the muscles. While such 

 action of the current may play a role in galvanotaxis, and may 

 control the galvanotactic response in some animals, it seems inade- 



7 In this paper near the top of the second column on page 523 the 

 statement that oligochsetes in a current travel to the anode should read 

 "travel to the cathode." 



