( 344 ) 
to be obtained; a mathemical expression or a graphic schema of this 
law was not in accordance with his results, as was demonstrated 
afterwards by 'TIGERSTEDT *). 
Neither does the psycho-physical law fit into the framework of 
muscle-stimulation. 
TIGERSTEDT’s hypothesis that the relation between stimulus and 
effect might possibly be expressed by a hyperbola, has already been 
rejected by himself. 
Hitherto then there does not exist a law expressing this relation 
with sufficient accuracy. 
In the following essay an endeavour is made to fill up this de- 
ficiency. I believe indeed to have succeeded, starting from a few 
definite premises, to establish a law indicating with great accuracy 
the relation between intensity of stimulus and effect. 
To begin with I intend giving the deduction of the law, to 
proceed afterwards to test this law to the results, obtained hitherto 
by experiments about muscle-contractions. In a following essay we 
shall try to examine whether this law holds good in other cases 
than those where muscle-contraction is concerned. 
As soon as a stimulus is applied to the muscle-protosplasma this 
last suffers a change. A part of it is transformed, and potential 
energy is developed by means of which labour may be performed. If 
K be the force of tension, then if K dt represents the whole of the 
potential energy. On this sum of the potential energy depends the 
performed external labour. 
If we call fx dt the effect or the quantity of muscular power 
made free, then we may deem this to be ultimately dependent ona 
quantity of changed chemical substance, on a number of transformed 
molecules. 
Supposing a stimulus & to be the cause of the transformation, by 
which a quantity / is transformed, we will see what is going on 
during a small particle of time. In a very small particle of time dt 
the stimulus may change for a certain amount dR, in consequence 
of which the quantity of matter is changed for a certain amount 
—dE. Under the restriction, that these increments are extremely 
small, we may admit proportionality between increment of stimulus 
1) 1. c. pag. 5. 
