G34 REVIEW — INAUGURAL DISSERTATION ON THE 
nervous filament, whence its influence is reflected to the proper 
motor filament. For the explanation of this ingenious theory, 
the reader is referred to Dr. Bennett’s work, or to Dr. Marshall 
Hall’s Lectures on the Nervous System. Dr. Bennett now 
sums up his account of the brain, and of the portions of it more 
immediately connected with motion, sensation, and intelligence, 
in the following clear and interesting statement : — 
The principal conclusions arrived at, may be shortly summed 
up as follows : — 
“ 1. The cortical substance of the brain furnishes the condi- 
tions necessary for mental acts. 
“ 2. The medullary portion is formed of three sets of fibres, 
and serves merely to conduct the influence of stimuli. 
“ The first set transmit the influence of volition from, and the result 
of impressions on, the external organs of sense to the cortical substance, 
so that we become conscious of such impressions. Hence they may 
be called the fibres of volition and consciousness. 
“ The second set connect together the two hemispheres of the brain, 
and convey the influence caused by mental changes from one to the 
other. 
“ The third set perform a similar office with regard to different parts 
of the same hemisphere. 
“ 3. Sensation, as it is at present understood by physiologists, 
expresses tw r o things : — 1st, That the influence of a stimulus has 
been conveyed to the sensitive column. 2dly, That this influ- 
ence has been continued through the fibres of the medullary 
portion of the brain to the cortical substance. In other words, 
we must be conscious of the impression that has been made, in 
order to produce a sensation. 
“ 4. The sensitive column commences superiorly with the optic 
thalamus on each side, forms the posterior part of the medulla 
oblongata and spinal cord, and terminates where the nerves are 
given off interiorly. 
“ 5. The motor column commences superiorly with the corpus 
striatum on each side, forms the anterior part of the medulla 
oblongata and spinal cord, and terminates where nerves are 
given off interiorly . 
“ 6. All associated movements are either voluntary or invo- 
luntary. 
“ Voluntary movements are excited by a mental stimulus arising in 
the cortical substance of the brain, which is transmitted to the motor 
column by the nerves of volition, and continued forward to the muscles 
moved. 
“ Involuntary associated movements are excited by chemical, or by 
mechanical stimuli, which are conveyed to the sensitive column by the 
