on.
Various birds can learn to repeat words or sentences used by their
masters or mistresses. In most cases probably the birds do not attach
their proper meaning to the words they have learnt; they repeat them in
season and out of season, sometimes apparently for their own amusement,
generally in the expectation, raised by past experience, of being
rewarded for their proficiency. But even here it is difficult to prove
a universal negative, and most possessors of such pets would repudiate
indignantly the statement that the bird did not understand what was said
to it, and would also contend that in many cases the words which it used
were employed in their ordinary meaning. The first dictum seems to be
inconsistent with fact. The case of deaf mutes, such as Laura Bridgeman,
who became well educated, or the still more extraordinary case of Helen
Keller, deaf, dumb, and blind, who in spite of these disadvantages
has learnt not only to reason but to reason better than the average of
persons possessed of all their senses, goes to show that language and
reason are not necessarily always in combination. Reason is but the
conscious adaptation of means to ends, and so defined is a faculty which
cannot be denied to many of the lower animals. In these days when so
many books on Animal Intelligence are issued from the press, it seems
unnecessary to labour the point. Yet none of these animals, except by
parrot-imitation, makes use of speech, because man alone possesses in a
sufficient degree of development the centres of nervous energy which are
required for the working of articulation in speech. On this subject much
investigation was carried on during the last years of Darwin's life
and much more in the period since his death. As early as 1861 Broca,
following up observations made by earlier French writers, located the
centre of articulate speech in the third left frontal convolution of
the brain. In 1876 he more definitely fixed the organ of speech in
"the posterior two-fifths of the third frontal convolution" (Macnamara,
"Human Speech", page 197, London, 1908.), both sides and not merely the
left being concerned in speech production. Owing however to the greater
use by most human beings of the right side of the body, the left side of
the brain, which is the motor centre for the right side of the body, is
more highly developed than its right side, which moves the left side
of the body. The investigations of Professors Ferrier, Sherrin