S.and B.in the University of Toronto on a class of students numbering nearly three hundred, of whom about one third were women.

The instructors showed to the class certain squares of cardboard of suitable size, and asked them to do the following three things on different days: First, to reproduce from memory, with pencil on paper, squares of the same size as those shown, after intervals of one, ten, twenty, and forty minutes (this gives results by the method of Reproduction); second, to say whether a new set of squares, which were shown to them after the same intervals, were the same in size as those which they had originally seen, smaller, or larger (illustrating the method of Identification); third, they were shown a number of squares of slightly different sizes, again at the same intervals, and asked to select from them the ones which they found to be the same size as those originally seen (method of Selection).
The results from all these experiments were combined with those of another series, secured from a large class of Princeton students; and the figure (Fig.

8) shows by curves something of the result.

The figure is given in order that the reader may understand by its explanation the "graphic method" of plotting statistical results, which, with various complications, is now employed in psychology as well as in the other positive sciences.
[Illustration: FIG.

8 .-- Memory curves: I.Method of Selection.