trace of the reddish-orange phase. The image
flashes out over the final fixation-point, green and straw-yellow,
just as the end-circles of the dumb-bell appeared without their
handle. The rate of succession of the stimuli, green--red--green, on
the retina, is identical with that rate which showed the two phases to
the resting eye: for the pendulum is here moving at the very same
rate, and the eye is moving exactly with the pendulum, as is shown by
the absence of any horizontal elongation of the image seen. The
trained subject seldom sees any other images than 4 and 5, and these
with about equal frequency, although either is often seen in ten or
fifteen consecutive trials. As in the cases of the falsely localized
images and of the handleless dumb-bell, movements of both eyes, as
well as of the head but not the eyes, yield the same phenomena. It is
interesting again to compare the appearance under reflex movement. If
at any time during the experiments the eye is allowed to follow the
pendulum reflexly, the image is at once and invariably seen to pass
through its two phases as it swings past the nine-centimeter opening.

The frequent and unmistakable appearance of this band of straw-yellow
on a non-elongated green field _without the previous phase in which
the band is reddish-orange_, although this latter was unmistakable
when the same stimulation was given to the eye at rest, is
authenticated by eight subjects. _This appearance, together with that
of the handleless dumb-bell, is submitted as a demonstration that
during voluntary movements of the eyes, and probably of the head as
well, there is a moment in which stimulations are not transmitted from
the retina to the cerebral cortex, that is, a moment of central
anaesthesia_. The reason for saying 'and _probably_ of the head as
well,' is that although the phenomena described are gotten equally
well from movements of the head, yet it is not perfectly certain that
when the head moves the eyes do not also move slightly within the
head, even when the attempt is made to keep them fixed.

Most of the criticisms which apply to this last experiment apply to
that with the dumb-bell and have already been answered. There is one
however which, while applying to that other, more particularly applies
here. It would be, that these after-images are too brief and
indistinct to be carefully observed, so that judgments as to their
shape, size, and color are not valid evidence. This is a per