the rest. The figures in Table II. have already shown what may be
expected when the points are kept from fusing. Here, also, a marked
tendency in the direction of apparent lengthening of the distance was
at once observed. These short filled distances, which had before been
underestimated, were now overestimated. The same results follow when
metallic points are alternated with hard rubber points in the filling
itself.

This changing of the apparent temperature of the end points has, it
must be admitted, introduced another factor; and it might be objected
that it was not so much the prevention of fusion as the change in the
temperature that caused the judgments to drift towards overestimation.
I have statistics to show that this observation is in a way just.
Extremes in temperature, whether hot or cold, are interpreted as an
increase in the amount of space. This conclusion has also been
reported from a number of other laboratories. My contention at this
point is simply that there are certain conditions under which these
distances will be overestimated and that these are the very conditions
which bring the phenomenon into closer correspondence with the optical
illusion, both as to the stimuli and the subjective experience. Then,
aside from this, such an objection will be seen to be quite irrelevant
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