to6 FUNCTIONAL INERTIA 



One of my earliest examples of psychic inertia 

 was that of ' the lack of correspondence between 

 sensation and stimulus as formulated in the Weber- 

 Fechner Law." I regarded the absence of response 

 to subliminal stimuli, the ineffectiveness of supra- 

 maximal stimuli to call forth any greater response 

 than did the maximal, as cases of physiological 

 inertia ; as also all the non-responses on the side of 

 consciousness to a whole series of increments of 

 stimulus from the last sensation-producing one to 

 the next. Once more I find Professor Sherrington 

 expressing himself in agreement with the tenor of 

 these views.* " Weber's Law may be a sort of 

 law of friction in the neural machine." The same 

 expression " friction " is used by the psychologist, 

 Professor James. I prefer to speak of inertia 

 rather than friction as the property of protoplasm 

 underlying the Weber Law on account of the wider 

 applicability of the principle of inertia to vital 

 phenomena ; although I am far from denying that 

 certain manifestations of vitality could not be as 

 appropriately described in terms of friction. As will be 

 apparent in the last chapter, molecular friction may be 

 the result of the still more primitive property of mole- 

 cular inertia ; in any case no one would deny that, 

 as properties of molecules, they are closely related. 



We are prepared for the generalisation that 

 those mental tendencies that are inherited are pre- 

 formed capacities and preadjusted endowments not 



* C. S. Sherrington in " Text-book of Physiology." Edited by 

 Schafer, vol. ii. p. 932. 



