62 FINGER PRINTS CHAP.
E. B. Titchener to make an adequate course of experiments at Professor Wundt's psycho-physical laboratory at Leipzig, to decide this question, He had the advantage there of being able to operate on fellow-students who were themselves skilled in such lines of investigation, so while his own experience was a considerable safeguard against errors of method, that safety was reinforced by the fact that his experiments were conducted under the watchful eyes of competent and critical friends. The result of the enquiry was decisive. It was proved to demonstration that the fineness or coarseness of the ridges in different persons had no effect whatever on the delicacy of their tactile discrimination. Moreover, it made no difference in the results, whether one or both points of the compass rested on the ridges or in the furrows.
The width of the ridge-interval is certainly no test of the relative power of discrimination of the different parts of the same hand, because, while the ridge-interval is nearly uniform over the whole of the palmar surface, the least distance between the compass points that gives the sensation of doubleness is more than four times greater when they are applied to some parts of the palm than when they are applied to the bulbs of the fingers.
The ridges may subserve another purpose in the act of touch, namely, that of enabling the character of surfaces to be perceived by the act of rubbing them with the fingers. We all of us perform this, as it were, intuitively. It is interesting to ask a
