340 Journal of Comparative Neurology and Psychology. 



readiness. In view of the fact that insects are capable of form- 

 ing quite complex associations and of guiding their action by their 

 previous experiences there is no reason to balk at the admission 

 of the possibility that an insect may seek the light because it 

 thereby derives an agreeable feeling. Whether the phototaxis 

 of Ranatra is to be interpreted as a form of pleasure seeking, or 

 as a matter of direct reflexes, a sort of behavior forced upon the 

 creature from without, is a question not to be decided without 

 careful observation and experiment. That an organism travels 

 towards the light in the direction of the rays, even though it 

 goes from a brighter area into a darker one, is no decisive proof 

 of the latter theory. We might interpret the orientation of an 

 animal going towards the light as due, not to forced reflexes, 

 but to a more or less voluntary effort to retain a maximum of 

 stimulation. If a creature has reached that plane of psychic 

 development at which it acquires a capacity of reacting with in- 

 creasing readiness to stimuli which produce an agreeable effect, 

 and of discontinuing those reactions which give rise to unpleas- 

 ant results, it seems probable that it would not stupidly continue 

 to orient its body and go towards the light if this were not asso- 

 ciated with some sort of gratification. If the organism be 

 capable of profiting by experience, we should expect such 

 meaningless behavior sooner or later to be stamped out. 



The impulses which are concerned in the reactions of 

 Ranatra to light pass through the principal centers of the 

 nervous system. The responses of the creature to light, if we 

 consider them as reflex acts, cannot, therefore, be reflexes of a 

 very simple kind. The impulses involved must pass from the 

 eye to the brain, thence through the sub-oesophageal ganglion 

 and the ganglia of the ventral nerve cord to the nerves supply- 

 ing the legs. There are several links in the chain of neurons 

 between the reception and the discharge of the stimulus, and 

 there is abundant opportunity afforded for modification of the 

 reaction through impulses coming from associated parts of the 

 nervous system. As a matter of fact, we have found that the 

 light reactions of Ranatra are modified in this way, as well as 

 conditioned by the general nervous state of the animal. And 



