( 705 ) 
This general property of the reflex-apparatus is called „augmenta- 
tion”. The myothermal investigations of Fick ') prove this very 
clearly for the production of heat in the muscle, and the staircase 
phenomenon proves the same for the mechanical effect. If a stimulus 
acts on a reflex-apparatus great enough to overcome the passive 
resistances, but whose increase per unit of time is too small to 
bring about a perceptible effect, this stimulus will produce a change 
in the reflex-apparatus, every successive stimulus will do the same 
in a more and more changed reflex-apparatus. At last the stimulus, 
which at first seemed too weak, will cause an external measurable 
effect. This phenomenon is called the “summation of stimulus”. 
It would be more accurate to speak of the summation of the effect 
of stimulation. 
If we again drop our premise of perfect isolation, no equilibrium 
can exist between the surrounding medium and the reflex-apparatus, 
unless the latter has perfectly returned to its initial state, as far as 
temperature and pressure are concerned. If this has happened, 
the chemical system returns also to its original state. In this case 
the cycle is complete. This latter part of the cycle is of course 
irreversible and proceeds at first very fast *), at the end very slowly. 
For the muscle-reflex-apparatus upon which the tonus depends, an 
interval lying between 3 and 5 minutes seems requisite for that 
part of the process *). For plants, with their more perfect isolation, 
this interval can exceed 30 minutes *). 
Following the example set by- MARSHALL HALL, GRAINGER, 
SHERRINGTON °) and many others I have considered the reflex-appa- 
ratus as a unit, because the normal course of the process of assimil- 
ation is bound to the integrity of the reflex-apparatus. If we inter- 
rupt the reflex-arc anywhere a lasting change takes place at once. 
As a proof of this we can adduce, that the tonicity of a muscle 
changes the moment the reflex-are on which the tonus rests, is 
interrupted °). In the second place the atrophy which the muscle 
and the gland show some time after their motor or secretory nerves 
has been cut through. As soon as the reflex-arc is interrupted, the 
reflex-apparatus passes still through a cycle as regards its physical state, 
but the chemical cycle is no longer complete. This incompleteness of 
1) Fick. Myothermische Untersuchungen. 1889 p. 120, 121. 
2) Warp. Archiv. f. Physiologie. 1880. p. 87. 
3) LANGELAAN. Proceedings Royal Acad. Amsterdam May 25th 1901. p. 50. 
4) CzaPEK. l.c. p. 207. 
*) SHERRINGTON. On the spinal animal. 1898 Repr. Thomas Yates Lab, Report p. 27, 
5) LANGELAAN, Archiv, f. Physiologie Jahrgang 1901, p, 119, 
