14 MANUAL OF ELEMENTARY ZOOLOGY 



is such as would in most circumstances be directly or 

 indirectly to his benefit, even though in particular circum- 

 stances it may compass his destruction, as when the natural 

 response to the stimulus given by the sight of things which 

 seem to be good for food causes a child to eat the berries 

 of the deadly nightshade. 1 But no such tendency can be 

 found in responses that take place in lifeless things. In- 

 ternal action there may be or not in response to external 

 changes, but such reaction, if it occur, is here|without regard 

 to the welfare of the body in which it takes place. A blow 

 given to a cartridge produces a response in the cartridge, 

 but the response is without purpose as regards the cartridge 

 and leads incidentally to its destruction. A blow given to 

 a living animal produces a response which varies indeed 

 according to circumstances but tends always, by flight or 

 by resistance, to the avoidance of danger. Action such as 

 this, with a tendency to the accomplishment of a definite 

 end in relation to the acting body, is said to be purposive. 

 It should be noted, however, that the use of this word 

 does not imply that the actions in question are directed 

 by will. The term is concerned only with the result of 

 the action, not with the means by which it is directed 

 to that result. Purposiveness pervades all the activities 

 of animals. It is not confined to direct response, but is 

 found also in automatic actions, which always tend to 

 the benefit of the being in whose body they occur. Need- 

 less to say the incorporation of food by which the body is 

 repaired and enlarged is as purposive as we have seen the 

 disintegration of its substance to be. On the other hand, 

 it must be recognised that reproduction, purposive though 

 it is, is directed, not to the welfare of the individual in 

 which it takes place, but to that of the whole species of 

 animal to which that individual belongs. Every kind of 

 animal is continually losing its individuals by death, and 

 it is obvious that unless there were provided by repro- 

 duction a constant succession of new individuals the species 

 would die out. Moreover, as we shall see, reproduction 



1 It is, of course, possible by unnatural stimuli to bring about quite 

 meaningless responses, as when electric shocks cause aimless movements 

 of the limbs. But even here the mechanism which is set in action is 

 that which in ordinary circumstances is used for purposive movements. 



