during the moment of stimulation, and consciousness of the same
process just afterward. In both his cases the stimulation was given
during the eye-movement, but there was nothing to prove that it was
perceived at just the same moment. Whatever the difficulties of
demonstrating an anæsthesia during movement, an experiment which does
not observe the mentioned distinction can never disprove the
hypothesis.

[Illustration: Fig. 2.]

For the sake of a better understanding of these bands of light of
Dodge, a perimeter was equipped in as nearly the manner described by
him (_ibid._, p. 460) as possible. Experiments with the eye moving
past a very narrow illuminated slit confirmed his observations. If the
light behind the slit was feeble, no band was seen; if moderately
bright, a band was always seen. The most striking fact, however, was
that the band was not localized behind the slit, but was projected on
to that point where the eye came to rest. The band seemed to appear
at this point and there to hover until it faded away. This apparent
anomaly of localization, which Dodge does not mention, suggests the
localization which Schwarz describes of his streaks. Hereupon the
apparatus was further modified so that, whereas Dodge had let the
stimulation take place only during the movement of the eye across a
narrow slit between two walls, now either one of these walls could be
taken away, allowing the stimulation to last for one half of the time
of movement, and this could be either the first or the second half at
pleasure. A plan of the perimeter so arranged is given in Fig. 2.

_PBCDB'P_ is the horizontal section of a semicircular perimeter of 30
cm. radius. _E_ is an eye-rest fixed at the centre of the semicircle;