CHAPTER 9 



Ultrastability in the Organism 



9/1. In the early sections of Chapter 7 we considered the ele- 

 mentary behavioural facts of the kitten adapting, and related 

 them to a mechanistic theoretical construction, the ' ultrastable ' 

 system. In the present chapter we will consider some further 

 elementary relations between the real organism and the theoretical 

 construct. We will consider, in particular, what can be said 

 about the simple theoretical system shown in Figure 7/5/1. How 

 does it correspond to the real organism and the real environment ? 

 We must go with caution, for experience has shown that a jump 

 to conclusions that are grossly in error is only too easy. 



9/2. We must be particularly careful not to take for granted 

 that a diagram of immediate effects — that of Figure 7/5/1 for 

 instance — gives a picture of what is to be seen in the nervous 

 system. Just as one real ' machine ' can give rise to a variety 

 of systems, so it can give rise to a variety of diagrams of immediate 

 effects, if the experimenter examines the real ' machine ' with a 

 variety of different technical methods. An electrical network, for 

 instance, may give very different diagrams of functional con- 

 nexion if it is explored first with slowly varying potentials and 

 then with potentials oscillating at a high frequency. Sometimes 

 it happens that two techniques may give the same diagram — 

 exploring a metallic network firstly with direct currents and then 

 by the sense of touch, say. When this happens we are delighted, 

 for we have found a simplicity; but we must not expect this to 

 happen always. 



Many simple bodies have one diagram that is so obtrusive that 

 one is apt to think of it as the specification of how the parts are 

 joined. This is the diagram built up by considering the parts' 

 positions in three-dimensional space, and studying how each part 

 moves when some other part is moved. In this way (using a 

 method just the same as that of S. 4/12) scientist and man in 



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