ughout the body until lost in fine
ramifications which the microscope can scarcely trace, but which
quickly inform us if they are touched or disturbed.

[Illustration]

It cannot properly be said that the spinal cord proceeds from the
brain, nor on the other hand that the brain proceeds from the spinal
cord, for they originate simultaneously in a soft, jelly-like
condition in which the microscope cannot detect the latent structure,
not as they are in the adult, but as they are in the foetus in which
they first appear, with a structure similar to that of the lowest
class of vertebrate animals, the fishes.

From this embryonic condition, in which there is very little
resemblance to the adult brain, its progress has been carefully traced
by many observers, but chiefly by Tiedemann, through all the stages of
life before birth into the soft, infantile form of the human brain.
Some knowledge of this embryonic growth is necessary to a correct
understanding of the adult brain, its essential plan, its growth, and
the correct estimate of its development.

I have not found in our anatomical works what I consider a
satisfactory exposition of this subject. Beginning as a student with
Spurzheim's anatomy of the brain, which ought to have been the
clearest and most complete of all, I found it so obscure and
unsatisfactory that until I had made many dissections I had no very
clear understanding. I have never found any pleasure in the writings
of Spurzheim. In more recent authors the anatomical details are very
abundant indeed, and sufficient to tax the _memory_ heavily, but
without that system and philosophy which appeal to the understanding
and make our conceptions satisfactory, as I hope to make them to my
readers, who must have very incorrect conceptions of the plan of the
brain, if they have relied upon the writings of Mr. Combe and his
successors of the phrenological school, none of whom, so far as I am
aware, have really understood cerebral anatomy.

Let us approach the subject by taking an exterior and general view,
then by tracing the embryonic growth of the brain, and the interior
connections of its fibres, until we are fully prepared to judge of its
development as it lies in the skull, and to understand the relation of
each organ to all other portions. Then we can study its functions with
a clear understanding of the relations of the organs to each other,
which is the material basis of psychic science, and with full
co