edge that the
following deductions of Gall are quite sound: "The convolutions ought to be
recognised as the parts where the instincts, feelings, thoughts, talents,
the affective qualities in general, and the moral and intellectual forces
are exercised." The Paris Academy of Science appointed a commission of
inquiry, May, 1808, which declared the doctrine of Gall to be erroneous.
Gall moreover surmised that the faculty of language lay in the frontal
lobes, and Bouillaud supported Gall's proposition by citing cases in which
speech had been affected during life, and in which after death the frontal
lobes were found to be damaged by disease. A great controversy ensued in
France; popular imagination was stirred up especially in the republic by
the doctrine of Gall, which was an attempt to materialise and localise
psychic processes. Unfortunately Gall's imagination, encouraged by a
widespread wave of popular sympathy, overstepped his judgment and launched
him into speculative hypotheses unsupported by facts. His doctrine of
Phrenology was shown to be absolutely illogical; consequently it was
forgotten that he was the pioneer of cerebral localisation.

SPEECH AND RIGHT-HANDEDNESS

The next step in Cerebral Localisation was made by a French physician, Marc
Dax, who first observed that disease of the left half of the cerebrum
producing paralysis of the right half of the body (right hemiplegia) was
associated with loss of articulate speech. This observation led to the
establishment of a most important fact in connection with speech, viz. that
right-handed people use their left cerebral hemisphere as the executive
portion of the brain in speech. Subsequently it was shown that when
left-handed people were paralysed on the left side by disease of the right
hemisphere, they lost their powers of speech. But the great majority of
people are born right-handed, consequently the right hand being especially
the instrument of the mind in the majority of people, the left hemisphere
is the leading hemisphere; and since probably specialisation of function of
the right hand (dexterity) has been so closely associated with that other
instrument of the mind, the vocal instrument of articulate speech, the two
have now become inseparable; for are not graphic signs and verbal signs
intimately interwoven in the development of language and human
intelligence?

What has determined the predominance of the left hemisphere in speech? I
can find n