BEHAVIOUR 95 



applicable, in the opinion of different students, to the 

 behaviour of insects generally, and indeed to that of animals 

 lower or higher in the scale of life than they. Already 

 comment has been made on the tendency to credit insects, 

 when they show response to stimulation of various kinds, 

 not only with sensations but with states of consciousness — 

 pleasure, discomfort, terror — comparable to those which we 

 realise in our own experience. The food-gathering activi- 

 ties of ants and bees look like conscious efforts directed 

 intelligently to an obvious purpose. That is the assumption 

 underlying the belief that such insects display industry and 

 foresight in their work. On the other hand, Anstey's verse 

 suggests that the purposeful activities of insects may be 

 carried on without design or knowledge on their part, and 

 such an outlook on the subject has become increasingly 

 popular during recent years. It is undeniable that a large 

 proportion of the actions of insects are reflexes resulting 

 directly from various stimulations from outside, which call 

 forth inevitable responses through the nervous system of 

 the insect acting on its muscles. The term " instinct," often 

 used somewhat loosely to describe the causes of actions not 

 due to intelligence on the part of the agent, has at its root 

 the idea of " need " or '' urge." But such urge or impulse 

 arises as the response of the organism to stimulation, and 

 instinct was therefore defined by Herbert Spencer as " com- 

 pound reflex action," and a creature's instinctive behaviour 

 has been regarded as the sum of its responses to environ- 

 mental influence. Stimulations are being continually 

 received by means of the various sense-organs, and the 

 insect's nervous system is of such a nature that certain 

 responses follow in each case. The simplest form of 

 response is some kind of tropism such as was described at 

 the close of the previous chapter (pp. 92-3), and some recent 

 distinguished students of insect behaviour — ^A. Bethe 

 (1898) and J. Loeb (1905), for example — believed that all 

 the life-activities of the creatures can be explained as a 

 complex of tropisms. Light, gravity, contact with particles 

 of soil, odorous plant secretions, all affect the insect and the 



