348 Journal of Comparative Neurology and Psychology. 



reflex theory of phototaxis. This is a feature of the creature's 

 behavior which, I am inclined to believe, we shall not be able 

 to understand until we can explain the physiology of the pro- 

 cess whereby certain stimuli when they have been received one 

 or more times are sought either directly, or indirectly, by a 

 more or less round-about method, while other stimuli when they 

 are experienced one or more times come to be avoided. Did 

 light afford a stimulus of an unpleasant nature, it is probable 

 that the positive phototaxis of Ranatra would soon be inhibited. 

 If the phototaxis of Rantra falls to a certain extent under the 

 category of reflex action, as much in its behavior indicates, the 

 reflexes concerned are in line with a strong instinctive interest 

 of the animal in seeking the light. This interest may lead to 

 successful attempts to get to the light in situations in which 

 purely reflex responses alone would fail. It acts as a sort of reg- 

 ulatory agent in the conduct of the insect, bringing its actions to 

 a successful issue, which could not be attained by a purely 

 machine-like mode of response. 



It is through instinctive interests in certain things rather 

 than by simple or even complex reflex acts that the conduct of 

 higher animals is mainly guided. The play activities of higher 

 animals, for instance, are performed, not because they are reflex 

 responses to particular things in the environment, but because 

 the animal is so constituted that it derives satisfaction from their 

 performance. An animal interest may be chained, by virtue of 

 its organization, to certain ends, such as the capture of a certain 

 kind of prey, or the construction of a particular kind of habita- 

 tion ; but at the same time its conduct may show considerable 

 plasticity as regards the methods by which these ends are at- 

 tained. In instinctive behavior, as in the morphogenic pro- 

 cesses which lead to the establishment and maintenance of the 

 normal form of the body there is an apparent effort to reach a 

 certain end result, despite obstacles and unusual conditions. 

 The explanation of this pecuHarity of animal behavior is a prob- 

 lem of fundamental interest. If we attempt to resolve highly 

 complex modes of behavior into simple direct reflexes, we soon 

 find ourselves at the end of our tether. Even in so apparently 



