I. THE PROBLEM OF ANÆSTHESIA DURING EYE-MOVEMENT.


A first suggestion of the possible presence of anæsthesia during
eye-movement is given by a very simple observation. All near objects
seen from a fairly rapidly moving car appear fused. No further
suggestion of their various contour is distinguishable than blurred
streaks of color arranged parallel, in a hazy stream which flows
rapidly past toward the rear of the train. Whereas if the eye is kept
constantly moving from object to object scarcely a suggestion of this
blurred appearance can be detected. The phenomenon is striking, since,
if the eye moves in the same direction as the train, it is certain
that the images on the retina succeed one another even more rapidly
than when the eye is at rest. A supposition which occurs to one at
once as a possible explanation is that perchance during eye-movement
the retinal stimulations do not affect consciousness.

On the other hand, if one fixates a fly which happens to be crawling
across the window-pane and follows its movements continuously, the
objects outside swim past as confusedly as ever, and the image of the
fly remains always distinct. Here the eye is moving, and it may be
rapidly, yet both the fly and the blurred landscape testify to a
thorough awareness of the retinal stimulations. There seems to be no
anæsthesia here. It may be, however, that the eye-movement which
follows a moving object is different from that which strikes out
independently across the visual field; and while in the former case
there is no anæsthesia, perhaps in the latter case there is
anæsthesia.