(17 ) 
from this a series of successive tonicity-quotients is extrapolated 
according to the law of FrcHNER. So this series of tonicity-quotients 
represents the probable value of the muscle-tone, corresponding toa 
group of successive increases of charge, if the stimulus had only passed 
through the primary muscle-reflex are. Then the inflection point in the 
curve is determined as accurately as possible. At this point the inhibiting 
influence which is exerted by the secondary on the primary muscle- 
reflex arc is zero. Also the real value of the tonicity-quotient for 
a certain increase of the charge is known from the measurements 
of the curve. But if by means of the before-mentioned extrapola- 
tion the probable value of the tonicity-quotient can be calculated, 
exclusively depending on the primary muscle-reflex arc and by 
direct measurements the tonicity-quotient under simultaneous influence 
of the two muscle-reflex arcs can be determined, and if the premise 
of the simple addition of these quantities is correct, it is possible 
to determine by simple subtraction of these quantities the value of 
the inhibiting influence exerted by the secondary muscle-reflex are. 
But if for two given charges the value of this influence is known, 
it is possible to interpolate a number of terms by means of the 
second premise. For this, terms were chosen corresponding to those 
for which the value of the tonicity-quotient was calculated, when 
the muscle was only under the influence of its primary muscle- 
reflex arc. The difference between these tonicity-quotients must 
then be identical with the tonicity-quotient, determined directly 
from the curves. We shall elucidate this method by a scheme. 
Let the curve ABC represent the value of the tonicity-quotients 
as function of the increase of the charge. In B a maximum is 
reached and this point coincides with the inflection-point on the 
distention-curve. Accordingly the influence of the secondary muscle- 
reflex are on the primary disappears at point B. Consequently 
F is the final point of the curve representing the extent of the 
tone-inhibition of the secondary muscle-reflex are on the primary. 
The portion between B and C represents therefore the value of the 
tonicity-quotient as function of the increase of the charge, when 
the muscle is exclusively under the influence of its primary muscle- 
reflec arc. Extrapolating according to the law of FEcHNER, BD is 
obtained, and curve DC becomes then the graphical representation 
of the value of the tonicity-quotient as function of the increase of 
charge, if the muscle had been only under the influence of its 
primary muscle-reflex arc all through the course of the experiment. 
OA is the value of the tonicity-quotient under influence of the 
2 
Proceedings Royal Acad. Amsterdam. Vol. IV, 
