THE WORLD OF LIVING ORGANISMS 159 



the material of the central nervous system. We have 

 absolutely no knowledge as to whether that is apperceived 

 by the animal. 



THE WORLD OF ACTION 



When we considered the world-as-sensed and the inner 

 world of animals, we could not fail to recognise a certain 

 parallelism between the physiological and biological ways of 

 considering them, a parallelism which permitted of the two 

 sciences being mutually complementary and corroborative ; 

 but when we turn to consider the world of action, this paral- 

 lelism completely disappears. 



According to physiological notions, every animal imparts 

 to the universe the effect released by the movements of its 

 limbs or the secretion of its glands. And in the universe, 

 these manifestations of the animal body continue their effect 

 from atom to atom according to the law of causality. In 

 principle, the step of a beetle's foot or the stroke of a dragon- 

 fly's wing must carry their effect as far as the dog-star. For, 

 according to the causal conception, even the smallest com- 

 ponent of natural phenomena is absolutely necessary, and 

 cannot be thought away from the general system of action 

 and reaction, without making the whole impossible. 



It is perfectly obvious that this point of view does not 

 do justice to the marvellously constructed effector apparatus 

 of animals. 



To appreciate rightly what the effector organs perform 

 in the function-circle, we must consider in more detail the 

 laws that govern our human implements. Hitherto we have 

 considered only our unified tools (such, for instance, as the 

 ladder), and shown that they have a framework constructed 

 in accordance with a function-rule, which fits them for a 

 counter-action in support of our human activities — in this case, 

 the act of climbing. 



