level, comprises those structures which receive sensory impulses from
the cells of the lowest level instead of directly from the periphery
or the non-nervous tissues. The motor cells of this middle level also
discharge into the motor mechanisms of the lowest level. Jackson
located these middle level structures in the cortex of the central
convolutions, the basal ganglia and the centers of the special senses
in the cortex. The highest level bears the same relation to the middle
level that it bears to the lowest i.e., no continuous connection
between the highest and the lowest is assumed; the structures of the
middle level mediate between them as a system of relays. According to
this hierarchical arrangement of the nervous system, the lowest level
which is the simplest and oldest "contains the mechanism for the
simple fundamental movements in reflexes and involuntary reactions.
The second level regroups these simple movements by combinations and
associations of cortical structure in wider, more complex mechanisms,
producing a higher class of movements. The highest level unifies the
whole nervous system and, according to Jackson, is the anatomical
basis of mind."

For a fuller account of this theory see Burk: From Fundamental to
Accessory in the Nervous System and of Movements. Pedagogical
Seminary, October, 1898, vol. 6, pp. 17-23.]

[Footnote 10: A Preliminary Study of Some of the Motor Phenomena of
Mental Effort. American Journal of Psychology, July, 1896, vol. 7, pp.
491-517.]

[Footnote 11: Encyclopedia of Social Reform, Funk and Wagnalls, 1896,
p. 1095]