(472) 
A simple consideration shows that in so doing we put a lineal function 
of the first degree in the place of the exponential function, in a 
case where the action of the stimulus on a nerve-fibre was concerned. 
Now in our two former essays we proved precisely that it is 
allowed to do so where the nerve is concerned, because this behaved 
as a purely transmissive organ, and because only in the case of 
infinitely stronger stimuli than those that practically occur, a lineal 
function of a higher degree or even an exponential function may be 
needed to explain in what manner the nerve-fibre itself behaves 
under the influence of stimuli. 
Consequently we obtain for the transmission of a stimulus froma 
first to a second excitable element — this last element being a 
nerve-fibre — the same expression, as the one originally esta- 
blished for the law expressing the relation between stimulus 
and effect in the case of one single organism. The above made 
demonstration may of course be extended to a third and a fourth 
element, the law always remaining unaltered and only tke con- 
stants being changed. From the foregoing we deduce the consequence 
that a priori it may be deemed very probable that for sense- 
stimulation too the effect is expressed by our law, though we must 
instantly add the restriction, that this may be expected to 
hold true only where momentary stimuli are concerned. For in 
establishing the law the time-function was neglected. From this 
we may not conclude that time does not exert any influence at 
all, but simply that the law prevails only in cases where that 
influence may be excluded. This is possible only in cases where 
the space of time, during which a stimulus is acting, is extra- 
ordinarily short‘), so that in reality the stimulus has finished 
acting before the effect reveals itself, consequently only for momen- 
taneous stimuli. 
Within my knowledge there have been made only a very few, 
and rather insufficient researches about the magnitude of the sense- 
perception in the case of momentary stimuli. For the present there- 
fore the efficacy of the law cannot be tested to these. 
It is possible however to investigate in how far this law is con- 
nected with the well-known psycho-physical law of WEBER-FECHNER. 
Previously to this we will show, how, guided by our former 
demonstrations, we may arrive at a biological explanation for the 
1) I have succeeded in finding an expression for the addition of stimuli, open- 
ing quite novel views on some as yet insufficiently explained physiological facts. 
