530 THE EVOLUTION OF MIND 



I 



plant goes on growing up to a certain limit, and this may 

 be for a time accelerative, as in the case of a green leaf, 

 which utilises more and more matter and energy the larger it 

 grows. The almost ceaseless movements of relatively simple 

 creatures, like jellyfishes, or of more complex creatures like 

 water-mites, or of still more complex forms like fishes, may 

 illustrate this organic inertia. Perhaps not very much higher 

 is the way in which a burrowing beetle-larva will eat on and, 

 on with little or no interruption under the bark of the tree, 

 until its constitution begins to change and it becomes a pupa 

 just below the surface. The degree of conation (if any) that 

 may be reasonably assumed in such cases, must remain at 

 present a matter of opinion. But organic momentum or 

 perseverance proves inadequate when there is persistent, yet 

 interrupted, co-ordination of activities towards a distant 

 result. The following interesting case is quoted by Professor 

 Hobhouse (Mind in Evolution, 2nd Ed., 1915, p. SO). 



" A sandhopper is feeding amongst seaweed and a crab 

 approaches behind a clump of weed; which he uses as 

 ' cover '. There was a distance of about eight inches be- 

 tween the two animals, which the crab had to cross without 

 alarming his victim. Presently he left his cover, and, crouch- 

 ing down, crept towards the sandhopper. When he had got 

 about half-way, the sandhopper stopped eating, and turned 

 towards the crab, which immediately disappeared in the sand. 

 Presently the sand rose nearer the sandhopper, the crab re- 

 appeared, took a stealthy step or two towards the victim, and 

 then sprang upon him. There are here a succession of acts 

 of diverse character watching, stealthy creeping, hiding, 

 and pouncing, all brought into operation as the case 

 required." . . . Here is a series of sensori-motor acts ad- 

 justed from moment to moment, not to a series of simple 



