1854.] OF THE ROYAL INSTITUTION. 379 
the vesicular portions of nervous matter, transmitted along the 
nervous fibres. If a nerve of sensation or of motion is divided, 
sensation and motion no longer exist below the divided part ; if the 
spinal column is injured, the parts supplied with nerves from portions 
of it below the injured portion are deprived of motion and of sensa- 
tion. If the medulla oblongata is severely injured, respiration 
ceases. Ifthe brain itself is variously injured or diseased, the sen- 
sations become untrue, the movements irregular, all the bodily 
functions usually suffer more or less disorder, and the mental 
‘faculties are variously impaired. But as nothing that we know of 
the optic nerve and its association with the corpora quadragemina 
explains the wonders of sight or the sense of the beautiful; and as 
the auditory nerve and its origins have no intelligible relation to 
the sense of melody: so, in equal ignorance, we curiously examine 
the convolutions of the brain, and fail to discover the repositories 
of memory, or any clue to its capricious failures or revelations. We 
are incapable of conceiving the connection between these arrange- 
ments of matter and the tender affections and divine fancies which 
are among the privileges of man. The inspiration of the painter or 
sculptor, the reasonings of the philosopher, the calculations of the 
astronomer, are, we know, dependent on certain states or actions 
in these elementary nervous tissues, but we feel that we have not 
advanced one step to knowing how. Here, as in all branches of 
enquiry fully pursued, we seem to arrive at the confines of material 
existence, and can but conjecture a finer agency, of which we only 
see the effects. 
We therefore return and rest upon the idea thaf the various forms 
- of Insanity may depend upon the excess, or deficiency, or inequality, 
of this nervous agency, whatever it is, in different portions of the 
nervous system. We find that thinking and muscular exertion 
equally produce fatigue and exhaustion; and that sleep is the 
general restorer of power in both cases. Various states of bodily 
disease declare its partial or imperfect distribution, temporarily or 
permanently ; the consequences being, increased, or deficient, or 
irregular action. The maniac seems often to require no sleep; the 
hysteric and the epileptic drop asleep after strong nervous excite- 
ment; and in patients affected with delusions, it is impossible not 
to recognise analogies which make their condition appear to be a 
state in which some of the faculties are not awake like the rest. 
The effects of stimulants and narcotics support the same view; and 
if we could comprehend the manner in which, by the inhalation of 
certain vapours and gases, all the relations between the external 
world and the brain are modified, we might arrive at some less 
vague notion than we possess of the actual condition of the nervous 
system both in health and disease. Disordered secretions, and a 
diseased state of the blood, may readily be supposed to act on the 
nervous system in such a manner as to disturb its functions; and 
the intimate and universal association of blood-vessels with nerves 
is additionally illustrated by the almost invariable combination of 
