138 ANIMAL BEHAVIOUR 



assimilate, the need is felt and rises into consciousness as hunger, 

 which becomes desire for food. The urge is then manifested 

 in behaviour, in hunting or in the other more ordinary ways of 

 procuring food. We eat, thus consummating what may be a 

 complex train of anticipatory activities. We may be placed in 

 conditions of personal danger and the urge to self-preservation 

 may manifest itself in deliberated effort — as when the master of 

 a ship makes thought-out preparations for avoiding the risks of 

 an approaching cyclonic storm. We feel the urge of reproduction 

 and that may be the stimulus to activities that are acutely present 

 in consciousness. If there is anything that we are certain about 

 it is that our own conduct expresses motive, or purpose, in the 

 most ordinary senses of those words. And not only are we 

 convinced that other men and women, behaving in the ways that 

 we behave, have the same general motives and purposes that we 

 have, but we are also convinced, from the similarity of their 

 behaviour, that hosts of animals also behave with motive, or pur- 

 pose, and have immediate feeling and knowledge that they do so. 



It is when the structure, and the patterns of behaviour exhibited 

 by the lower vertebrates and most of the invertebrate animals 

 differ widely from ours that this extension of our own feelings 

 and motives to them becomes difficult. Partly this is due to 

 our lack of familiarity with the behaviour of these organisms — 

 and it is notable that when the activities of even so primitive 

 an animal as an infusorian are closely studied the less unfamiliar 

 do its activities appear : it has been said that the organism 

 behaves in the way that we do when we say that we act intelli- 

 gently. Partly the difficulty comes from the attitude that was 

 once held — that animals lower than man were properly to be 

 regarded as automata. Mainly, however, it is the result of too 

 much laboratory training. It has been said that natural history 

 of the old kind is only to be called " science by courtesy." The 

 ascription of purpose to the lower animals was called *' anthropo- 

 morphism " and was something to be avoided. The tendency 

 to study animal activity in terms of tropisms, taxis, " con- 

 catenated " and *' conditioned " reflexes and so on was regarded 

 as a much more scientific one ! 



We can regard an organism as a physico-chemical system. As 

 such it continually tends to chemical degradation and energetic 

 dissipation. Yet it maintains equilibrium, continuing to renew 



