18 
C. L. Herrick 
We must distinguish the content of sense from sensation.^® 
Here is the source of great confusion. Too often the content 
of sense is confused with sense perception. The content of sense 
at any given time is the sum of the affections of the lower or 
primary sesthesodic centers. In the visual field, for example, 
it is the totality of the immediate central reactions corresponding 
to the retinal excitations. We may think of them as distributed 
over homologous parts of the optic tectum; but it is probable that 
we should add the effects of certain optic reflexes set up with their 
sesthesodic reactions, and not improbable that it will be necessary 
to include modifications or accretions due to changes in the cor- 
tical visual area; but as yet there is no sensation, only a sense-con- 
tent. Besides the contents of special senses — vision, audition, taste, 
smell — there is the whole sesthesodic contingent from the spinal 
cord, many of which never become sensations normally but may 
be brought into consciousness under exceptional conditions. 
Some perhaps are capable of entering sensation only as a quale 
of some other, having no localizable tag suiting them to indej)en- 
dent recognition or isolation. These, however, are just as real 
a part of the content of sense as the pre-sensational elements of 
color or pain. 
Now it is evident to ordinary experience that in many cases the 
act" of sensing a sense-content is really an act, not an occurrence. 
We fix that particular element. It is immaterial how we are 
impelled to the fixation. It is an expression of our spontaneity, 
a reaction of the subject. Many considerations justify us in 
supposing that an act of consciousness is a reaction of conscious- 
ness. There are, it is true, in the sense-content of vision focal 
and marginal impressions, but the physical mechanism is well 
known. There is something similar in the auditory field whose 
physical mechanism is obscure. There is nothing of the sort 
in the other senses except skin-sensation and there the physical 
origin is beautifully illustrated by the localization experiments. 
The localization apparatus of the senses has apparently suggested ^ 
the theory of focal and marginal consciousness. We believe that a 
proper interpretation of experience removes the ground for this 
assumption. The various intensities of sense-impressions con- 
iK Cf . ‘‘Focal and Marginal Consciousness/’ Psychological Review, vol. 3, 1896, pp. 
193-195. 
