
THE LINGERING ADMIRERS OF PHRENOLOGY. 591 
it issues from, which acts upon the cord. Thus, for example, 
when the cord near its upper part is severed from the brain 
by an injury, there is loss of all sensation and voluntary 
motion in the parts supplied by it below the place of lesion, 
the consciousness being no longer in communication with 
those parts; but irritation of the integument still sends a 
current as before to the spinal cord, and this being dis- 
tributed by the corpuscles of the gray matter, and descend- 
ing again by the motor nerves, causes involuntary contraction 
of muscles. This is probably the simplest possible example 
of the phenomenon termed by physiologists reflex nervous 
action. 
We have ventured on this extremely cursory and general 
survey of the spinal cord, the simplest portion of thé cere- 
brospinal axis, in order that the general reader may form 
some conception of the kind of mechanism which extends 
through the more obscure and intricate portion, the brain. 
. To explain fully the extremely complex structure of the 
brain would require much greater detail than is allowable in 
an article like this, but a general idea of the most important 
faets will best be arrived at by pursuing the aecount of its 
early development, which we have already begun. 
The cylinder which we have traced in the embryo, so far 
as the spinal cord is concerned, is immediately on its closure, 
expanded in its cranial part into a series of three primordial 
vesicles, and immediately afterwards two little hollow buds, 
called the hemisphere vesicles, project laterally from the fore- 
most of the series. Without tracing the history of the pri- 
mordial vesicles, it is sufficient for our present purpose to 
point out that the cerebellum is originally a part of the hin- 
dermost, projecting upwards as a hollow pouch, and that it 
is quite certain, from the experiments on lower animals, that 
no consciousness whatever resides in any of the parts devel- 
 Oped from that vesicle; also it is equally certain that not 
= more than the very feeblest consciousness resides in those 
parts into which the walls of the two other primordial vesi- 
