ULTRASTABILITY IN THE LIVING ORGANISM 



9/2 



excitations in the motor cortex certainly control the rat's bodily 

 movements, and such excitations have no direct effect on any of 

 the other five groups of variables ; so we can insert arrow 1, 

 and know that no other arrow leaves that box. (The single 

 arrow, of course, represents a complex channel.) Similarly, the 

 other arrows of the diagram can be inserted. Some of the 

 arrows, e.g. 2 and 4, represent a linkage in which there is not 



a positive physical action all the time ; but here, in accordance 

 with S. 2/3, we regard them as permanently linked though some- 

 times acting at zero degree. 



Having completed the diagram, we notice that it forms a 

 functional circuit. The system is complete and isolated, and 

 may therefore be treated as absolute. To apply our thesis, we 

 assume that the cerebral part, represented by the boxes around 

 arrow 6, contains step -functions whose critical states will be 

 transgressed if stimuli of more than physiological intensity are 

 sent to the brain. 



We now regard the system as straightforwardly ultrastable, 

 and predict what its behaviour must be. It is started, by hypo- 

 thesis, from an initial state at which the voltage is high. This 

 being so, the excitation at the skin and in the brain will be high. 

 At first the pattern of impulses sent to the muscles does not 

 cause that pedal movement which would lower the voltage on 

 the grill. These high excitations in the brain will cause some 

 step-functions to change value, thus causing different patterns 

 of body movement to occur. The step-functions act directly 

 only at stage 6, but changes there will (S. 14/11) affect the field 



107 



