( 708 ) 
the whole system must pass into a changed state of equilibrium. If 
the other circumstances remain unchanged, the new state of equili- 
brium will be determined by the stimulus measured in physical 
units !). The real relation between the stimulus measured in physieal 
measure and the change in the system not being known, we must 
for the present represent it by an implicite function. The same 
holds good for the quantity of transformed energy, as we generally 
measure only part of it in our experiments. 
If we now apply the before-mentioned formula to the transition 
of the system of the products of assimilation to that of the products 
of dissimilation, we find for a reflex-apparatus: 
he <r Oee a ae 
p (£) 
In this formula the quantity of transformed energy is PE 
by #(£) and the value of the stimulus in physical units by R 
For a reflex-apparatus with passive resistances, as it only occurs in 
nature, only the sign of inequality has sense. 
As in our experiments of stimulation never one single rech 
organ is stimulated, but always a great number, we must summate 
the above expression between 0 and x, x being the number of 
stimulated elements. 
) 
NE Ap (B) 
EAFE)ZKE a 
If we do not understand by Ag() the change as it really 
occurs in a certain receptive-organ, but the average change, we 
may write: 
=A p(R)=r7A G(R) 
As the number of stimulated receptive-organs is always a function 
of the extent of the stimulated area, we are led to introduce, as 
HeuMHoLrz did*), this quantity in the formula of stimulation. The 
representation of the effect of stimulation as a sum has no sense, 
as it is shown by the researches of Ramén y CAJAL *) and many 
others, how great the number of connections is between the afferent 
and the efferent nerves. In the second place this decomposition 
has no sense as by its construction the transformer is to be con- 
sidered as a whole. By introducing a new proportionality constant 
the above formula goes over in: 
1) The way by whiche this changed state is reached, however, is not determined 
by the stimulus, and this enables us to determine or modify by external circum- 
stances the distribution of the transformed energy over different forms. 
2) Hetmuortz. Handb. physiol. Optik. 1896. p. 409. 
*) Ramon y Casa, Nuevo Concepto de la Histologia de los Centros nerviosos 1893. 
