The Story of Evolution 75 



creature's activity which we call mind. We cannot put our 

 finger on any point and say: Before this stage there was no 

 mind. Indeed, many facts suggest the conclusion that wherever 

 there is life there is some degree of mind even in the plants. Or 

 it might be more accurate to put the conclusion in another way, 

 that the activity we call life has always in some degree an inner 

 or mental aspect. 



In another part of this book there is an account of the dawn 

 of mind in backboned animals; what we aim at here is an 

 outline of what may be called the inclined plane of animal 

 behaviour. 



A very simple animal accumulates a little store of potential 

 energy, and it proceeds to expend this, like an explosive, by 

 acting on its environment. It does so in a very characteristic 

 self-preservative fashion, so that it burns without being consumed 

 and explodes without being blown to bits. It is characteristic of 

 the organism that it remains a going concern for a longer or 

 shorter period its length of life. Living creatures that ex- 

 pended their energy ineffectively or self -destructively would be 

 eliminated in the struggle for existence. When a simple one-celled 

 organism explores a corner of the field seen under a microscope, 

 behaving to all appearance very like a dog scouring a field seen 

 through a telescope, it seems permissible to think of something 

 corresponding to mental endeavour associated with its activity. 

 This impression is strengthened when an amoeba pursues another 

 amoeba, overtakes it, engulfs it, loses it, pursues it again, re- 

 captures it, and so on. What is quite certain is that the behaviour 

 of the animalcule is not like that of a potassium pill fizz- 

 ing about in a basin of water, nor like the lurching movements 

 of a gun that has got loose and "taken charge" on board ship. 

 Another feature is that the locomotor activity of an animalcule 

 often shows a distinct individuality: it may swim, for instance, in 

 a loose spiral. 



But there is another side to vital activity besides acting upon 



