16/7 ADAPTATION IN THE MULTISTABLE SYSTEM 



system is assumed to have its own essential variables and second 

 order feedback. Figure 16/6/1 illustrates the connexions, but 

 somewhat inadequately, for it shows only three subsystems. (It 

 should be compared with Figures 15/7/1 and 15/8/1.) 



Figure 16/6/1. 



Such a system is essentially similar to the multistable system 

 denned in the first edition. (The system denned there allowed 

 more freedom in the connexions between the main variables, e.g. 

 from reacting part to reacting part, and between reacting part and 

 an environmental subsystem other than that chiefly joined to it; 

 these minor variations are a nuisance and of little importance — 

 in the next chapter we shall be considering such variations.) 



16/7. To trace the behaviour of the multistable system, suppose 

 that we are observing two of the subsystems, e.g. A and B of 

 Figure 16/6/1, that their main variables are directly linked so 

 that changes of either immediately affects the other, and that for 

 some reason all the other subsystems are inactive. 



The first point to notice is that, as the other subsystems are 

 inactive, their presence may be ignored; for they become like the 

 4 background ' of S. 6/1. Even if some are active, they can still 

 be ignored if the two observed subsystems are separated from 

 them by a wall of inactive subsystems (S. 12/10). 



The next point to notice is that the two subsystems, regarded 

 as a unit, form a whole which is ultrastable. This whole will 

 therefore proceed, through the usual series of events, to a terminal 



209 



