( 656 } 
value behaving entirely like a counter E.M. F of polarisation, which 
as we know, according to BARTOLI may be represented in the 
manner indicated here. 
In a former essay we have demonstrated the addition of stimuli 
to be a corrective, by means of which feeble stimuli were observed 
to act with greater intensity than in the case of their being only 
of short duration. Meanwhile we have seen that with stronger 
stimuli the effect diminishes very rapidly. In this way the possibility 
occurs, that the relative differential threshold-value will remain fairly 
constant over a comparatively large part of the curve, and that for the 
sharp bend, mentioned in my last communication, will be substituted a 
slower and more regular course of the curve. For the moment | 
cannot enter into details concerning this point. 
Ad. III and IV. As a necessary consequence of the manner of 
deduction, chosen for these equations, we ought to postulate the 
existence of rhythmical effects, under the influence of instantaneous 
and constant stimuli. The occurrence of similar effects in physiology 
is beyond any doubt. Among the most convincing proofs on this 
point we may rank the beautiful curves published by 5. Garten, 
about the course of the potential oscillations of the action current 
in a muscle, in which suddenly a transverse section is made, or in 
the case of stimulation by a strong battery-current. In both cases 
he demonstrated the existence of damped vibrations, possessing an 
extraordinarily regular course, and answering wholly to formula (2) 
or formula (3). 
But in the animal organism there may occur other series of 
rhythmic, nearly sinusoidal oscillations, being however not damped. 
I believe these too might be mathematically treated. One might 
be induced to think that some of these oscillations will appear 
as soon as the coefficient q in the equation (9) is so small that 
practically the first differential quotient is omitted from the equation. 
For in this case undamped, sinusoidal effects would be originated. 
It is not impossible indeed, that perhaps for certain effects 
the damping may be so slight, that sinusoidal effects of con- 
stant amplitude are achieved. I have in view, amongst other facts, 
the rhythmic innervation passing from the secondary to the primary 
neuron under the influence of impulses of will, or of cerebral 
or spinal excitation; cases of pathological and of physio- 
logical tremor. Meantime I believe these phenomena generally to 
present some particulars, denoting that we ought to think here 
