by reference to inequality in the metronomic intervals).  That the rhythmical phases which appear in the accompaniment are not due to inequality in the stimulation intervals, is shown by the reversal of relations between the metronome and its accompaniment which occur in the midst of a continuous series of taps.  To speak roughly, a break occurs every twentieth beat.  I do not refer to minor irregularities occurring within the single group but not affecting the form of the rhythmical accompaniment.  The latter appeared with surprising rarity, but when found were included in the continuous calculation of averages.  But in every score or so of beats a stroke out of series would be interpolated, giving the form | 1 >2 [1] 2 >1 |; the accompaniment being cooerdinated during the second portion of the whole series with opposite phases of the metronome from those with which its elements were connected in the earlier part.  Moreover, the dependence of this grouping of the sounds on subjective attitudes may readily be made to appear.  When attention is turned keenly on the process its phases of rhythmical differentiation decline; when the accompaniment becomes mechanical they mount in value.  When the observer tries to mark the ticking as accurately as possible, not only does the index of his motor reactions become more constant, but the sounds of the instrument likewise appear more uniform.  The observers report also that at one and the same time they are aware of the regularity of the metronome and the rhythmical nature of their tapping, while yet the conviction remains that the accompaniment has been in time with the beats.  Furthermore, if the phases of ticking in the metronome were temporarily unlike, the motor accompaniment by a series of observers, if accurate, should reproduce the time-values of the process, and if inaccurate, should present only an increase of the mean variation, without altering the characteristic relations of the two phases.  On the other hand, if the series be uniform and subjectively rhythmized by the hearer, there should be expected definite perversions of the objective relations, presenting a series of increasing departures from the original in proportion as the tendency to rhythmize varied from individual to individual.

On the other hand, a rhythm is already presented in the sounds of the metronome, occasioned by the qualitative differentiation of the members of each pair of ticks, a variation which it was impossible to eliminate and which must be borne in mind in estimating the following results.

Five reactors took part in the experiment, the results of which are tabulated in the following pages.  The figures are based on series of one hundred reactions for each subject, fifty accompaniments to each swing and return of the metronome pendulum.  When taken in series of ten successive pairs of reactions, five repetitions of the series will be given as the basis of each average.  The quantitative results are stated in Tables VII.-XIV., which present the proportional values of the time intervals elapsing between the successive reactions of an accompaniment to the strokes of a metronome beating at the rates of 60, 90 and 120 per minute.