CHAPTER 10 



Step-Functions in the 

 Living Organism 



10/1. In S. 9/4 the existence of step-functions in the living 

 organism was deduced from the observed facts. But so far 

 nothing has been said, other than S. 7/6, about their physio- 

 logical nature. What evidence is there of a more practical nature 

 to support this deduction and to provide further details ? 



Direct evidence of the existence of step-functions in the living 

 organism is almost entirely lacking. What evidence exists will 

 be reviewed in this chapter. But the lack of evidence does not, 

 of course, prove that such variables do not occur, for no one, so 

 far as I am aware, has made a systematic search for them. 

 Several reasons have contributed to this neglect. Their signi- 

 ficance has not been appreciated, so if they have been mentioned 

 in the literature they were probably mentioned only casually; 

 and since they show a behaviour bordering on total immobility, 

 they would usually have been regarded as uninteresting, and 

 may not have been recorded even when observed. It is to be 

 hoped that the recognition of the fundamental part which they 

 play in the processes of adaptation, of integration, and of co- 

 ordination, may lead to a fuller knowledge of their actual nature. 

 ' The anatomical localisation ', said Claude Bernard, c is often 

 revealed first through the analysis of the physiological process.' 

 Here I can do no more than to indicate some possibilities. 



10/2. Every cell contains many variables that might change in 

 a way approximating to the step-function form, especially if the 

 time of observation is long compared with the average time of 

 cellular events. Monomolecular films, protein solutions, enzyme 

 systems, concentrations of hydrogen and other ions, oxidation- 

 reduction potentials, adsorbed layers, and many other constituents 

 or processes might behave as step-functions. 



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