Hofbauer demonstrated that a stimulus which appears in close proximity to the limiting sensation, either before or after, always increases the force of the reaction, so that such a slight displacement could not affect the rhythm, which would quickly readjust itself.  The possibility of a stimulus occurring in the relaxation phase is of much more importance for a motor theory of the initiation of a rhythmic movement.  Cleghorn made the stimulus occur at the beginning of the relaxation phase.  Instead of prolonging or reinstating the contraction phase, he found that the stimulus intensified the relaxation process and shortened its period.  “The stimulated relaxation is not only quicker than the normal, but also more complete; the end of the normal relaxation is slow; ... relaxation under the influence of the stimulus, on the contrary, shows nothing of this, but is a sudden sharp drop directly to the base line and sometimes below it.”  A comparison of the normal phases with the same phases, when the stimulus occurs within the relaxation phase, follows: 

Normal:  Contraction-phase, .44 sec.; relaxation-phase, .54 sec.;
total, .98 sec. 
With stim.:  Contraction-phase, .47 sec.:  relaxation-phase, .30 sec.;
total, .77 sec.

It will be noticed that the total time of the movement cycle is reduced.  One may then assume that a sound which occurs too early to become a factor in the limiting sensation, functions as a stimulus to the relaxation process and shortens the interval between the limiting sensations.  Thus the movement cycle would be modified, but not destroyed.  It is impossible to say just how the relaxation process is affected, and Cleghorn’s own conclusions are open to criticism in the light of Mueller’s comments on the method.  The simplest assumption would be that the stimulus acted on the negative set of muscles.

E.W.  Scripture[23] objects to such a ‘tonus theory,’ because some subjects regularly react before the signal.  But in no case in the published records to which he refers is the error more than.05 sec. either before or after the signal.  The investigation of Hofbauer shows conclusively that in such cases the effect of the external stimulus simply fuses with the limiting sensation.  Scripture overlooks the automatic character of the rhythmic movement.

   [23] Scripture, E.W.:  ‘The New Psychology,’ London, 1897, p. 182.

There is a striking difference between rhythmic movement from unit group to unit group within a period, and movement from period to period (i.e., from verse to verse of nonsense syllables).  Each foot is simply the repetition of the movement cycle; all the tensions are maintained, and each foot is an integral part of a larger act.  At the close of the period (verse) the active tensions die out, either because of the introduction of some unusual stimulus which causes the positive muscle set to strike a heavy blow, and abruptly upset the balanced tensions, or because a pause of indefinite length ensues in which the tensions die out.  This is the process which we call ‘finality.’