( 1030 ) 
beginning of the curvature, “the reaction-time” was found to be 
experimentally undeterminable. Thus the latter can not serve as a 
measure of sensitiveness. 
It is more and more evident that such concepts as “Erregung” 
and “Erregungshéhe” can be perfectly well dispensed with, because 
the phenomena do not give the slightest indication of their use. 
Similarly the determination of an index or time of relaxation will 
be found impossible, because it is impossible to show experimentally 
that no curvature results from the summation of intermittent stimuli. 
Since the presentation-time has been conceived as a factor of the 
quantity of energy, which is just able to traverse the threshold of 
stimulation, it follows from the above investigations, that when the 
“Schwelle’ is abandoned the presentation-time loses mnch of its 
value as a special stimulation period. It remains however, as a time 
factor of the quantity of energy, which results in a curvature of 
definite strength. 
Henceforth therefore the physiology of stimulation must be inves- 
tigated by considering the energy which is applied as stimulus and 
which is determined by the product of the intensity of the operating 
force and the length of the stimulation period, whilst the reaction 
can be gauged by the degree of the maximal curvature, at least if 
the unilateral action of gravity is not eliminated. If the latter be 
Curvature-time in minutes. 
10 20 30 40 50 60 70 80 90 
Energy in M, G. S. 
Fig. 6. 
Relation between nergy and the time untill the curvature 
becomes just macroscopicatly visible, 
