648 PSTCIIOLOGY. 



facts is thus not only seen to be arbitrary and subjective, 

 but in the highest degree improbable as well. The depart- 

 ures from Weber's law in regions where it does not obtain, 

 he explains by the compounding with it of other unknown 

 laws which mask its eflects. As if any law could not be 

 found in any set of phenomena, provided one have the wit to 

 invent enough other coexisting laws to overlap and neutral- 

 ize it ! The whole outcome of the discussion, so far as 

 Fechner's theories are concerned, is indeed nil. Weber^s 

 law alone remains true as an empirical generalization of fair 

 extent : What we add to a large stimulus we notice less 

 than what we add to a small one, unless it happen rela- 

 tively to the stimttlvs to be as great. 



Weber's laio is probably purely physiological. 



One can express this state of things otherwise by saying 

 that the whole of the stimulus does not seem to be effective 

 in giving us the perception of ' more,' and the simplest in- 

 terpretation of such a state of tluDgs would be physical. 

 The loss of effect would take place in the nervous system. 

 If our feelings resulted from a condition of the nerve- 

 molecules which it grew ever more difficult for the stimulus 

 to increase, our feelings would naturally grow at a slower 

 rate than the stimulus itself. An ever larger part of the 

 latter's work would go to overcoming the resistances, and 

 an ever smaller part to the realization of the feeling-bring- 

 ing state. Weber's law would thus be a sort of laio of 

 friction in the neural machine.* Just how these inner 

 resistances and frictions are to be conceived is a specu- 

 lative question. Delboeuf has formulated them as fa- 

 tigue ; Bernstein and Ward, as irradiations. The latest, 

 and probably the most ' real,' hypothesis is that of Ebbing- 

 haus, who supposes that the intensity of sensation depends 

 on the number of neural molecules which ar^ disintegrated 

 in the unit of time. There are only a certain number at 

 any time which are capable of disintegrating ; and whilst 

 most of these are in an average condition of instability, 



* Elsas : Ueber die Psychophysik (18S6), p. 41, When the pans of 

 a balance are already loaded, but in equilibrium, it takes a proportionally 

 larger weight added to one of them to incline the beam. 



