hypothesis of anæsthesia. He proceeded as follows (_ibid._, p. 458):
"A disc of black cardboard thirteen inches in diameter, in which a
circle of one-eighth inch round holes, one half inch apart, had been
punched close to the periphery all around, was made to revolve at such
a velocity that, while the light from the holes fused to a bright
circle when the eye was at rest, when the eye moved in the direction
of the disc's rotation from one fixation point, seen through the fused
circle of light, to another one inch distant, three clear-cut round
holes were seen much brighter than the band of light out of which they
seemed to emerge. This was only possible when the velocity of the
holes was sufficient to keep their images at exactly the same spot on
the retina during the movement of the eye. The significant thing is
that the individual round spots of light thus seen were much more
intense than the fused line of light seen while the eyes were at rest.
Neither my assistant nor I was able to detect any difference in
brightness between them and the background when altogether
unobstructed." Dodge finds that this experiment 'disproves' the
hypothesis of anæsthesia.

If by 'anæsthesia' is meant a condition of the retinal end-organs in
which they should be momentarily indifferent to excitation by
light-waves, the hypothesis is indeed disproved, for obviously the
'three clear-cut round holes' which appeared as bright as the
unobstructed background were due to a summation of the light which
reached the retina during the movement, through three holes of the
disc, and which fell on the same three spots of the retina as long as
the disc and the eyeball were moving at the same angular rate. But
such a momentary anæsthesia of the retina itself would in any case,
from our knowledge of its physiological and chemical structure, be
utterly inconceivable.