can take place thither from other parts of the brain, among which are
the centers for color-sensations. The word 'tension' is of course a
figure, but it expresses the familiar idea that centers which are in
process of receiving peripheral stimulations, radiate that energy
_to_ other parts of the brain (according to the neural dispositions),
and probably do not for the time being receive communications
therefrom, since those other parts are now less strongly excited. It
is, therefore, most probable that during the incoming of the
eye-muscle sensations the centers for color are in fact not able to
discharge through their usual channels toward the localization-centers,
since the tension in that direction is too high. If, now, their other
channels of discharge are too few or too little used to come into
question, the action-theory would find in this a simple explanation of
the visual anæsthesia.

The fact that the anæsthesia commences appreciably later than the
movement so far favors this interpretation. For if the anæsthesia is
conditioned by high tension in the localization-centers, due to
incoming sensations from the eye-muscles, it could not possibly
commence synchronously with the movement. For, first the sensory
end-organs in the eye-muscles (or perhaps in the ligaments, surfaces
of the eye-sockets, etc.) have their latent period; then the
stimulation has to travel to the brain; and lastly it probably has to
initiate there a summation-process equivalent to another latent
period. These three processes would account very readily for what we
may call the latent period of the anæsthesia, as observed in the
experiments. It is true that this latent period was observed only in
long eye-and head-movements, but the experiments were not delicate
enough in this particular to bring out the finer points.