DESIGN FOR A BRAIN 



2/15 



from a system that is isolated. Thus, an experimenter may 

 subject a Protozoon to a drug at a certain concentration; he then 

 observes, without further experimental interference, the whole line 

 of behaviour (which may be long and complex) that follows. This 

 case occurs with sufficient frequency in biological systems and in 

 this book to deserve a special name; it will be referred to here as 

 a state-determined system. 



Table 2/15/1. 



As illustration of the definition, consider Table 2/15/1, which 

 shows two lines of behaviour from a system that is not state- 

 determined. On the first line of behaviour the state x = 0, 

 y = 2-0 was followed after 0-1 seconds by the state x = 0-2, 



Figure 2/15/1 : Field of a simple pendulum 40 cm. long swinging in a 

 vertical plane when g is 981 cm./sec. 2 . x is the angle of deviation from 

 the vertical and y the angular velocity of movement. Cross-strokes 

 mark the position of the representative point at each one-tenth second. 

 The clockwise direction should be noticed. 



26 



