10/9 THE RECURRENT SITUATION 



behaved in the past (for by hypothesis they are to give none now, 

 and they are the only source). Thus somewhere in the system 

 there must be this information stored; and these stores must not 

 be accessible while P 2 is acting, or they will be affected by the 

 events and the stored information over-written. Thus there must 

 be separate stores for P ± and P 2 , and provision for their separate 

 use.) 



Next, consider the channel from the essential variables. In 

 condition P 2 , the channel from them to the step-mechanisms in 

 #2 was evidently open, for events at the essential variables (whether 

 within physiological limits or not) affected what happened in 

 S 2 (by the ordinary processes of adaptation). On the other hand, 

 during this time the channel from the essential variables to the 

 step-mechanisms in S x was evidently closed, for changes in the 

 essential variables were followed by no changes in the step- 

 mechanisms of S v Thus the channel from the essential variables 

 to the step-mechanisms S must be divisible into sections, so that 

 some can conduct while the others do not; and the determination 

 of which is to conduct must be, at least partly, under the control 

 of the conditions P, varying as P varies between P ± and P 2 . 



Finally, consider the channels from S ± and S 2 to the reacting 

 part R. When P x is applied for the second time, the channel 

 from S 2 to R is evidently closed, for though the parameters in S 2 

 are changed (before and after P 2 ), yet no change occurs in R's 

 behaviour (by hypothesis). On the other hand, that from S x is 

 evidently open, for it is S^s values that determine the behaviour 

 under P v and it is the adapted form that is made to appear. 



10/9. To summarise: — Let it be given that the organism has 

 adapted to P x by trial and error, then it adapted similarly to P 2 , 

 and that when P 1 was given for the second time the organism 

 was adapted at once, without further trials. From this we may 

 deduce that the step-mechanisms must be divisible into non- 

 overlapping sets, that the reactions to P x and P 2 must each be 

 due to their particular sets, and that the presentation of the 

 problem (i.e. the value of P) must determine which set is to 

 be brought into functional connexion, the remainder being left in 

 functional isolation. 



Thus if the diagram of Figure 7/5/1 is taken as basic, it must 

 be modified so that the step-mechanisms are split into sets, there 



143 



