CONFORMITY WITH PLAN 277 



organ, but also a new rule in the action-organ that controls 

 the muscles of the syrinx. Accordingly, formation of new 

 framework has come in both in the mark-organ and in the 

 action-organ ; so we may assume an invasion by impulses. 



The plasticity of the action based on experience bears on 

 the direction itself, and not merely on the rule of working, 

 as it is in the case of the instinctive action, which Js subject 

 to an unchanging direction. As a result, the instinctive action 

 appears from its very inception fully prepared, whereas the 

 action of experience must be learnt gradually. Simple actions 

 based on experience, if often repeated, may become reflexes. 



R MOI->AOI E 



THE CONTROLLED ACTION = y — <- — j 



The bull-finch that has learnt to pipe a new tune forgets 

 it again if it is prevented from hearing its own voice. 

 This demonstrates the necessity of controlling the animal's 

 own effectors by its own receptors. The controlled action is 

 an action based on experience that does not become a reflex 

 and then run automatically. On the contrary, the new rule 

 of direction in the action-organ requires to have its running 

 continuously controlled by the mark-organ ; and, in order to 

 develop into greater permanence, the rule of direction that 

 has been newly formed in the mark-organ has need of the con- 

 tinued influence of the rule of working in the action-organ. 

 To grasp these complicated combinations, it is useful to make 

 a diagram of the steering-mechanism of a simple controlled 



action. >' — 0=0 *" is the diagram of the steering- 

 R MO Ao e 



mechanism as I gave it when describing the function-circle. 



^^"0^=0 \ is that of the steering-mechanism when we 



have to do with a controlled action, in which the influence 

 of the effectors on the receptors occurs outside the body, 

 as happens in the case of listening to one's own singing. 



