locality, in proportion as the part is supplied with end-organs from the
deep afferent system. When, however, the stimulus evokes pain the
sensation will tend to be referred into remote parts.
Now, just as one part of the affected area on H.'s hand seemed to be linked with some other remote portion, so visceral sensory surfaces seem to be closely associated with somatic segmental areas. When pain is evoked, it is not localized in the organ stimulated, but is referred to some area on the surface of the body.
Thus, the retention, on the primary level, of afferent impulses, which, if not inhibited, would lead to incorrect localization, has a protective object. To the normal organism they would be worse than useless, but in disease they underlie widespread pain and uncontrollable muscular reflexes.
The sensory processes discussed in this chapter take place on the physiological level. Psychological analysis fails entirely to disclose the struggle of sensory impulses revealed by our experiment. Integration occurs as impulses pass from the periphery towards the higher centres; the change is a constant one from a complex to a simpler and more specific grouping. Sensation, the final end of the process, assumes forms simpler than any sensory impulses.
We believe that the essential elements exposed by our analysis owe their origin to the developmental history of the nervous system. They reveal the means by which an imperfect organism has struggled towards improved functions and psychical unity.
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