Schumann maintains that the percepts of the series can exist only singly in consciousness: firstly, because he finds this to be the case by introspection; secondly, because from the principle that like successive impressions arouse nervous discharges in the same central organ, it follows that each psycho-physical process arising from the stimuli of the series would coalesce with the effects remaining over from the preceding stimulus. Hence, only single percepts could come into consciousness, and the process of comparison of the two series consists in the holding the first series in memory, while the recurring members of the second are checked off against those of the first — one after another.
As corroborative of his own view, Wundt recalls the fact that immediately after the ending of the first series, and just as the second begins, one has a perfectly clear feeling whether one will or will not be able to compare the two, and asserts that his introspection shows him that the series can exist as a whole, remarking, however, that it is a dubious business to dispute about results of self-observation when there is no objective test to decide the question. Wundt considers the comparisons of series of successive impressions as an especially pronounced case of the action of the feelings given in sudden acts of recognition.
In an earlier research (Phil. Stud. Bd. V) L. had sought to show that all associative processes, which most psychologists had considered as associations through similarity, could easily be explained as associations of contiguity, and that while all the results of experiments on recognition could be explained by the latter theory, association by similarity could only explain a part. In the present article he maintains his views against Höffding's attacks (V. f. W. Ph., 1889-1891), and with experimental aid assails Höffding's theory of association through similarity.
According to Höffding the recognition of a previously experienced sensation takes place by means of the "quality of familiarity" which belongs to the sensation in virtue of its repetition: the physical correlative of this quality is the greater facility with which the molecules of the brain respond to the repeated stimulus.
L.'s view is that recognition takes place by means of the reproduced ideas accompanying the repeated sensation, which ideas may or may not be found by introspection, and he contends against Höffding that a disposition towards greater facility of motion in the brain molecules can neither produce a sensation nor the elements of one, but may produce the shade of feeling often remarked in acts of recognition.
In support of his own views, Höffding advances the facts of immedi-
