CORRELATION BETWEEN METABOLIC GRADIENTS. 



341 



end is generally curved toward the cathode, the attitude being, 

 therefore, similar to that of the earthworms. 



In Nereis the galvanotactic behavior is, like the electrical gra- 

 dient, dependent upon the freshness of the individuals. It ap- 

 pears, although this has not been conclusively established, that very 

 freshly collected animals are cathodic ; they bend their bodies into 

 a U-shape, with anterior and posterior ends directed toward the 

 cathode. Animals which have been kept in the laboratory (and 

 probably also sexually ripe animals) are anodic. They assume the 

 U-position, but with anterior and posterior ends directed toward 

 the anode, and middle toward the cathode. All of the individuals 

 recorded in Table VI., of which the anterior ends are negatively 

 charged (int.), were found to be anodic. 



TABLE VI. 



ELECTRICAL GRADIENT OF Nereis virens AND Nereis vexillosa AFTER BEING 



KEPT IN THE LABORATORY. 



Ant., anterior; mid., middle; post., posterior; rd., readings on galvanom- 

 eter. Negative and positive refer to direction through the galvanometer. 



Nereis vexillosa. 



Nereis virens. 



