5.  The period composed of a number of unit groups (the verse, in nonsense syllables) has a general form which suggests strongly that it has the unity of a single cooerdinated movement.  There is no more reason for assuming a transcendental mental activity in the case of a rhythmic period than in the case of a single act which appears in consciousness as a unity.  Undoubtedly the breathing is correlated with the rhythmic movements and may be a factor in determining the verse period.  Meumann’s principal accent, about which a number of subordinate accents are grouped, is characteristic not only of poetry but of the simplest rhythms.  At some point in the period there is a definite climax, a chief accent; the movement ‘rises’ to that point and then falls off.  This is strikingly seen in nonsense verses spoken with a heavy accent within the verse.  The accent does not stand out from a dead level, but the verse culminates at that point.

Unfortunately very little is known of the mechanism of so simple a cooerdinated muscular activity as that necessary for a simple rhythm.  Sherrington[17] and Hering[18]have pointed out the primary character of the grouping of the muscles in opposing sets and the reciprocal nature of almost all muscular activity, but in a review of the work of cooerdinated movements Hering denies any simultaneous stimulation of the two sets and considers the question of the innervation mechanism of opposing muscle-sets entirely unsettled.

   [17] Sherrington, C.S.:  Proceedings Royal Soc., 1897, p. 415.

   [18] Hering, H.E.:  Archiv f. d. ges.  Physiol. (Pflueger’s),
   1897, Bd. 68, S. 222; ibid., 1898, Bd. 70, S. 559.

That the connection between the positive and negative set of muscles in a rhythmic movement is very close, and that the reaction is of the circular type, is evident from the automatic character of all rhythmic movements, and it is evident that the limiting sensation is the primary cue in the reaction.  Anything further is mere hypothesis.  Robert Mueller’s[19] thorough criticism of the Mosso ergograph throws great doubt on the present methods of investigation and invalidates conclusions from the various curves of voluntary movements which have been obtained.

   [19] Mueller, R.:  Phil.  Stud., 1901, Bd. 17, S. 1.

The curve of contraction and relaxation of a simple muscle is well known and is not affected by Mueller’s criticism.  Its chief characteristic, with or without opposing tension, is the inequality of the intervals of the contraction and relaxation phases.  As one might expect, since a single set of muscles dominates in a rhythmic movement, the typical rhythmic curve has the general character of the curve of the simple muscle.  The average values of the phases of curves of simple rhythmic movement obtained by A. Cleghorn[20] from a large number of observations with at least three subjects, are as follows:  phase of contraction, .44 second; phase of relaxation, .54 second.  It is very significant for a motor theory of rhythm that this general form of the curve of rhythmic movement may easily be altered in all sorts of fashions by unusual stimuli to the two muscle sets.