save one.

This subject, G. S., was far-sighted, and, after having obtained some data from him at 30 cm., the distance was changed to 40 cm. This enabled him to accommodate with greater ease and his results showed greater regularity, especially with the letters nearer the fixation point. Only the results obtained at the farther distance were retained, but this would scarcely have been necessary because the averages in the two sets of data differed little from each other. This being true, no attempt was made to adjust the results for distance. in order to make them comparable with those obtained from the other subjects. They appear to be comparable as they stand. What was gained by bringing the image of the letter nearer to the center of the fovea seems to have been lost by decreasing the size of that image. The extent upon the retina on which an object can be recognized depends directly upon the size of the object, and inversely upon its distance from the eye.

In this part of the research, data were obtained from eighteen subjects, but not the same amount from each. That from eleven only was regarded sufficient to be tabulated in detail (Tables I to VII). From the remaining seven, however, enough were obtained to be used in the correlations. The deviation at which the letters could be distinguished seventy-five per cent of the time was determined with a fair degree of assurance in all, and the ninety per cent deviation in three (see Table VIII).

The chief reason why more could not be obtained from these, and why full data could not be obtained from each subject, was the limitation in the amount of time that could be given to the work, especially by the subject. To get full data from one subject required approximately thirty hours. This is clearly too much time to give to one subject in a study purporting to ascertain individual differences, and indicates that the method adopted is not feasible for this kind of work. Something more rapid is needed when individual differences are looked for, so that more ground may be covered. This might be achieved by using as a unit the circle with one-eighth of the circumference left open. This would allow but one chance in eight to guess its position, whereas the n and the u allowed one chance in two. Results could therefore be obtained more rapidly.

Full data from a subject consisted in the exploration of four meridians, the horizontal, the vertical, and two oblique meridians midway between these, i. e., at forty-five degrees, this to be done for both eyes together, and for each eye separately. All these meridians were explored in only four subjects. In three others the horizontal and the vertical meridians were explored in both eyes and in each