If it be objected that the difference of their in-
ternal organisation cannot be proved by anatomy,
I repeat that which I already stated with respect
to the parts of the spinal cord, or nerves of sen-
sation and voluntary motion ; viz. that their differ-
ence, too, cannot be proved by anatomy, but that
it is admitted fi-ora physiological proofs. The
same will be the case with the cerebral portions.
II. In certain Idiots, individual Portions of the
Brain are defective, or even wanting.
It is evident that a disorder in the internal
organisation of the brain and its parts may pre-
vent the manifestations of the mind; but it is also
certain that sometimes individual portions of the
brain are defective in their development, remain
more or less in their embryonic .state, or arc en-
tirely wanting. Why should this not happen in
the cerebral portions, as well as in the nervous
apparatuses of the external senses? There are
various cases of monsters on record, who were de-
prived of the olfactory or optic nerve ; othei's arc
born with imperfect brains. In the Zeilschnft
[ fiir Physiologic, published by Tiedemann and Tre-



r



IB APPEHDIX TO THE

viranus, several defective brains of monsters are
described and represented. There is one whose
surface is smooth, without convolutions, as io the
lower animals and in the embryo of man. In my
work on the Anatomy of the Brain, I gave the
figure of the brain of an idiotic girl, who died at
Cork in Ireland, in comparison with the brain of
an ouraug-outang, kept in alcohol in the Garden
of Plants at Paris. I lay here by the drawings
of such a brain in the possession of Mr. Stanley,
by whose kindness I was allowed to take them.
