Chapter 10 



REGULATION IN BIOLOGICAL 



SYSTEMS 



10/1. The two previous Parts have treated of Mechanism (and the 

 processes within the system) and Variety (and the processes of com- 

 munication between system and system). These two subjects had 

 to be studied first, as they are fundamental. Now we shall use them, 

 and in Part III we shall study what is the central theme of cybernetics 

 — regulation and control. 



This first chapter reviews the place of regulation in biology, 

 and shows briefly why it is of fundamental importance. It shows 

 how regulation is essentially related to the flow of variety. The 

 next chapter (11) studies this relation in more detail, and displays 

 a quantitative law — that the quantity of regulation that can be 

 achieved is bounded by the quantity of information that can be 

 transmitted in a certain channel. The next chapter (12) takes up 

 the question of how the abstract principles of chapter 1 1 are to be 

 embodied — what sort of machinery can perform what is wanted. 

 This chapter introduces a new sort of machine, the Markovian, 

 which extends the possibihties considered in Part I. The remaining 

 chapters consider the achievement of regulation and control as the 

 difficulties increase, particularly those that arise when the system 

 becomes very large. 



At first, in Part III, we will assume that the regulator is already 

 provided, either by being inborn, by being specially made by a 

 manufacturer, or by some other means. The question of what made 

 the regulator, of how the regulator, which does such useful things, 

 came itself to be made will be taken up at S. 13/10. 



10/2. The present chapter aims primarily at supplying motive to 

 the reader, by showing that the subjects discussed in the later chapters 

 (11 onwards) are of fundamental importance in biology. The 

 subject of regulation in biology is so vast that no single chapter can 

 do it justice. Cannon's Wisdom of the Body treated it adequately 

 so far as internal, vegetative activities are concerned, but there has 



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