ADAPTATION AS STABILITY 5/15 



sentative point moves towards B, y hardly alters ; but x, which 



started at X', moves to X and goes past it to X" . Then x remains 



almost constant and y changes until the representative point 



reaches C. Then y stops changing, 



and x changes towards, and reaches, 



its resting value X. The system has 



now reached its resting state and no 



further changes occur. This account 



is just a transcription into words of 



what the field defines graphically. 



Now the shape and features of „ 



\ Figure 5/14/1. 



any field depend ultimately on the 



real physical and chemical construction of the ' machine ' from 

 which the variables are abstracted. The fact that the line of 

 behaviour does not run straight from A to R must be due to 

 some feature in the 4 machine ' such that if the machine is to 

 get from state A to state R, states B and C must be passed 

 through of necessity. Thus, if the machine contained moving 

 parts, their shapes might prohibit the direct route from A to R ; 

 or if the system were chemical the prohibition might be thermo- 

 dynamic. But in either case, if the observer watched the machine 

 work, and thought it alive, he might say : ' How clever ! x 

 couldn't get from A to R directly because this bar was in the 

 way ; so x went to B, which made y carry x from B to C ; and 

 once at C, x could get straight back to R. I believe x shows 

 foresight.' 



Both points of view are reasonable. A stable system may 

 be regarded both as blindly obeying the laws of its nature, and 

 also as showing a rudimentary skill in getting back to its resting 

 state in spite of obstacles. 



5/15. The second property is shown when an organism reacts to 

 a variable with which it is not directly in contact. Suppose, 

 for instance, that the diagram of immediate effects (S. 4/12) is 

 that of Figure 5/15/1 ; the variables have been divided by the 

 dotted line into ' animal ' on the right and 4 environment ' on 

 the left, and the animal is not in direct contact with the variable 

 marked X. The system is assumed to be stable, i.e. to have 

 arrived at the ' adapted ' condition (S. 5/7). If disturbed, its 

 changes will show co-ordination of part with part (S. 5/14), and 



69 f 



