ULTRASTABILITY IN THE LIVING ORGANISM 9/3 



A more elaborate reaction by the homeostat is shown in 

 Figure 9/3/1. 



1 



\r 



V 



tt 



Time 



Figure 9/3/1 : Three units interacting. At R the effect 

 of 2 on 3 was reversed in polarity. 



The machine was arranged so that its diagram of immediate 

 effects was 



>3 



The effect 3 — > 1 was set permanently so that a movement of 

 3 made 1 move in the opposite direction. The action 1 — > 2 

 was uniselector-controlled, and 2 — > 3 hand-controlled. When 

 the tracing commenced, the actions 1 — > 2 and 2 — > 3 were 

 demonstrated by the downward movement, forced by the operator, 

 of 1 at S t : 2 followed 1 downward (similar movement), and 3 

 followed 2 downward (similar movement). 3 then forced 1 up- 

 ward, opposed the original movement, and produced stability. 

 At R, the hand-control (2 — > 3) was reversed, so that 2 now 

 forced 3 to move in the opposite direction to itself. This change 

 set up a vicious circle and destroyed the stability ; but uniselector 

 changes occurred until the stability was restored. A forced 

 downward movement of 1, at S 2 , demonstrated the regained 

 stability. 



109 



