of lip and
tongue in their normal speech are injured as described.

Besides the two forms of Motor Aphasia now spoken of, there are
certain other speech defects which are called Sensory Aphasia. When a
lesion occurs in one of the areas of the brain in the speech zone in
which the requisite memories of words seen or heard have their
seat--as when a ball player is struck over the sight centre in the
back of the head--special forms of sensory aphasia show themselves.
The ball player will, in this case, have Visual Aphasia, being unable
to speak in proportion as he is accustomed in his speaking to depend
upon the images of written or printed words. He is quite unable to
read or write from a copy which he sees; but he may be able,
nevertheless, to write from dictation, and also to repeat words which
are spoken to him. This is because in these latter performances he
uses his auditory centre, and not the visual. There are, indeed, some
persons who are so independent of vision that the loss of the visual
centre does not much impair their normal speech.

When, again, an injury comes to the auditory centre in the temporal
region, we find the converse of the case just described; the defect is
then called Auditory Aphasia. The patient can not now speak or write
words which he hears, and can not speak spontaneously in proportion as
he is accustomed to depend upon his memories of the word sounds. But
in most cases he can still both speak and write printed or written
words which he sees before him.

These cases may serve to give the reader an idea of the remarkable
delicacy and complexity of the function of speech. It becomes more
evident when, instead of cases of gross lesion, which destroy a whole
centre, or cut the connections between centres, we have disease of the
brain which merely destroys a few cells in the gray matter here or
there. We then find partial loss of speech, such as is seen in
patients who lack only certain classes of words; perhaps the verbs, or
the conjunctions, or proper names, etc.; or in the patients who
speak, but yet do not say what they mean; or, again, in persons who
have two verbal series going on at once, one of which they can not
control, and which they often attribute to an enemy inside them, in
control of the vocal organs, or to a persecutor outside whose abuse
they can not avoid hearing. In cases of violent sick headache we often
miscall objects without detecting it ourselves, and in delirium the