Animal Instincts and Tropisms 273 



the forward motion is rendered easy, the backward 

 motion is difficult. Hence it can easily move toward 



the anode, but only with difficulty toward the cathode. 

 If a current be sent through the animal in the opposite 

 direction, namely, from head to tail, the third pair 

 of legs is extended, the fifth pair bent; that is, the third 



18 



