experiment require the
orange to be given if the straw-yellow is, since the straw-yellow
which is seen can be produced only by the addition of green to the
orange which is not seen.

These two phenomena seem inevitably to demonstrate a moment during
which a process on the retina, of sufficient duration and intensity
ordinarily to determine a corresponding conscious state, is
nevertheless prevented from doing so. One inclines to imagine a
retraction of dendrites, which breaks the connection between the
central end of the optic nerve and the occipital centers of vision.

The fact of anaesthesia demonstrated, other phenomena are now available
with further information. From the phenomena of the 'falsely
localized' images it follows that at least in voluntary eye-movements
of considerable arc (30 deg. or more), the anaesthesia commences
appreciably later than the movement. The falsely localized streak is
not generated before the eye moves, but is yet seen before the
correctly localized streak, as is shown by the relative intensities of
the two. The anaesthesia must intervene between the two appearances.
The conjecture of Schwarz, that the fainter streak is but a second
appearance of the stronger, is undoubtedly right.

We know too that the anaesthesia depends on a mechanism central of the
retina, for stimulations are received during movement but not
transmitted to consciousness till afterward. This would be further
shown if it should be found that movements of the head, no less than
those of the eyes, condition the anaesthesia. As before said, it is not
certain that the eyes do not move slightly in the head while the head
moves. The movement of the eyes must then be very slight, and the
anaesthesia correspondingly either brief or discontinuous. Whereas, the
phenomena are the same when the head moves 90 deg. as when the eyes move
that amount. It seems probable, then, that voluntary movements of the
head do equally condition the anaesthesia.

We have seen, too, that in reflex eye-or head-movements no anaesthesia
is so far to be demonstrated. The closeness with which the eye follows
the unexpected gyrations of a slowly waving rush-light, proves that
the reflex movement is produced by a succession of brief impulses
(probably from the cerebellum), each one of which carries the eye
through only a very short distance. It is an interesting question,
whether there is an instant of anaesthesia for each one of these
involuntary in