( 653 ¥ 
If the restorative power of the muscle may not be called infinite, 
e.g. in the case of the dissected muscle of a frog, B is no longer 
a constant, but an ever diminishing magnitude. For in this case the 
quantity of protoplasma, destined to replace the fatigue-products, is 
no longer maintained by the supply of blood, keeping the 
freshly supplied substance in equilibrium with that consumed, but the 
quantity is limited and continually diminishes. Here therefore we 
shall have to alter the assimilation-term in such a manner that for 
the constant B is substituted a term steadily decreasing in 
magnitude, e.g. Best, 
Probably in so doing we shall obtain an expression offering a 
more accurate represention of what practically occurs. 
The formula then will become: 
P=(1—e«?R){ Ae_.:+ Best (1 —e-#} . . . (19) 
In the case too of a muscle receiving a regular fresh supply of 
new substance, it may occur that this supply is conveyed less 
promptly than is necessary for even a minimum of regularly 
performed labour. In such cases there will come a moment, when 
no more work can be done. Yet fresh substance is continually 
supplied, and after some lapse of time the moment may come 
that the stimulus is enabled anew to transform a sufficient quantity 
of protoplasma to occasion one or more contractions, which however 
will soon cease again. In this way we obtain finally rhythmic effects, 
to be classified partly under the range of groups II] and IV. 
In formula (15) we have given an expression for the action of 
a biological constant stimulus. We may likewise make use of this 
formula in the case of the stimulus being only physically constant. 
Such is the case e.g. with the constant galvanic current. As we 
know, this stimulus possesses only an initial effect, soon descending 
again. This denotes @ and A4 being very great, whilst B is small. 
In this case we may without any inconvenience simplify the 
formula by neglecting the term containing B. If furthermore we 
restrict ourselves to a small intensity of current, and may conse- 
quently take R and P to be proportional to the intensity of current, 
this latter being eer dn by i, the formula will finally stand as 
follows : 
Pz Aiet Pt nae) 
This is the law established and proved by Hoonwse. As however 
for currents of great intensity we are not allowed to neglect the 
B-term, (15, offers a complete and more correct image of the action 
of a constant current upon nerve or muscle, explaining at the same 
time the possibility of tetanus in the case of stimulation by stronger 
