following physiological experiment throws light on this subject. A dog that
had been deprived of sight by removal of the eyes when it was a puppy found
its way about as well as a normal dog; but an animal made blind by removal
of the occipital lobes of the brain was quite stupid and had great
difficulty in finding its way about. Helen Keller's brain, as shown by her
accomplishments in later life, was a remarkable one; not long after birth
she became deaf and blind, consequently there was practically only one
avenue of intelligence left open for the education of that brain, viz. the
tactile kinæsthetic. But the tactile motor sense is the active sense that
waits upon and contributes to every other sense. The hand is the instrument
of the mind and the agent of the will; consequently the tactile motor sense
is intimately associated in its structural representation in the brain with
every other sense. This avenue being open in Helen Keller, was used by her
teacher to the greatest possible advantage, and all the innate
potentialities of a brain naturally endowed with remarkable intellectual
powers were fully developed, and those cortical structures which normally
serve as the terminal stations (_vide_ fig. 16) for the reception and
analysis of light and sound vibrations were utilised to the full by Helen
Keller by means of association tracts connecting them with the tactile
motor central stations. The brain acts as a whole in even the simplest
mental processes by virtue of the fact that the so-called functional
centres in the brain are not isolated fields of consciousness, but are
inextricably associated one with another by association fibres.




THE PRIMARY REVIVAL OF SOME SENSATIONS IN THE BRAIN