if we bear in mind that when the end points in the filled distance were replaced by metallic points, metallic points were also employed in the open distance.  The temperature factor, therefore, entered into both spaces alike.  By approaching the problem from still another point of view, I obtained even more conclusive evidence that it is the fusion of the end points with the adjacent points in the short distances that leads to the underestimation of these.  I have several series in which the end points were prevented from fusing into the filling, by raising or lowering them in the apparatus, so that they came in contact with the skin just after or before the intermediate points.  When the contacts were arranged in this way, the tendency to underestimate the filled spaces was very much lessened, and with some subjects the tendency passed over into a decided overestimation.  This, it will be seen, is a confirmation of the results in Table II.

I have already stated that the two series of experiments reported in Section II. throughout point to the conclusion that an increase of pressure is taken to mean an increase in the distance.  I now carried on some further experiments with short filled distances, making variations in the place at which the pressure was increased.  I found a maximum tendency to underestimate when the central points in the filled space were weighted more than the end points.  A strong drift in the opposite direction was noticed when the end points were heavier than the intermediate ones.  It is not so much the pressure as a whole, as the place at which it is applied, that causes the variations in the judgments of length.  In these experiments the total weights of the points were the same in both cases.  An increase of the weight on the end points with an equivalent diminution of the weights on the intervening points gave the end points greater distinctness apparently and rendered them less likely to disappear from the judgments.

At this stage in the inquiry as to the cause of the underestimation of short distances, I began some auxiliary experiments on the problem of the localization of cutaneous impressions, which I hoped would throw light on the way in which the fusion or displacement that I have just described takes place.  These studies in the localization of touch sensations were made partly with a modification of the Jastrow aesthesiometer and partly with an attachment to the apparatus before described (Fig. 1).  In the first case, the arm upon which the impressions were given was screened from the subject’s view, and he made a record of his judgments on a drawing of the arm.  The criticism made by Pillsbury[6] upon this method of recording the judgments in the localization of touch sensations will not apply to my experiments, for I was concerned only with the relative, not with the absolute position of the points.  In the case of the other experiments, a card with a single line of numbered points was placed as nearly as possible over the line along which the contacts had been made on the arm.  The subject then named those points on the card which seemed directly over the points which had been touched.