253 
THE EXCITO-MOTORY SYSTEM OF NERVES. 
[We mean not to enter into the controversy which the introduc¬ 
tion of this new and ingenious system of nervous action has 
occasioned ; but the veterinary pupil should keep pace with the 
knowledge of the times. This system is nowhere more con¬ 
cisely or clearly stated than in a recent lecture by Dr. Marshall 
Hall, published in The Lancet. —Y.] 
The functions of the cerebral system are, sensation, percep¬ 
tion, judgment, volition, and voluntary motion. The sensations are 
conveyed to the cerebrum by the sentient nerves, the olfactory, the 
optic, the acoustic, the trifacial and posterior spinal. The cere¬ 
brum itself may be viewed as the organ on which the sits, as 
it were, enthroned ; the voluntary nerves convey the mandates of 
the volition to the muscles which are to be called into action. 
All these functions are strictly physical; they imply conscious¬ 
ness. Sensation without consciousness appears to me to be a 
contradiction in terms; the idea and the phraseology should be 
banished from physiology. 
The cerebral system sleeps, sensation is dull, volition quiescent; 
dreams, &c. are the delirium of sleep. 
How different from those which I have thus enumerated are 
the functions which belong to the true spinal marrow'! In these 
there is no sensation, no volition, no consciousness, nothing 
physical. An impression is made upon the extremity of a 
nerve; this impression is conveyed, not to the cerebrum, but to 
some part of the medulla oblongata, or medulla spinalis, whence 
it is reflected upon certain muscles destined to be excited into 
consentaneous action. The true spinal system is independent of 
the cerebrum, and subsists when the cerebral lobes are removed. 
It guards, as it were, the orifices and exits of the body, regulating 
the ingesta and the egesta. 
The cerebral system is the seat of the intellect; the true spinal 
marrow is, in an especial manner, the organ of the emotions and 
passions. It is on this part of the nervous system that the pre¬ 
servation of the individual and the continuation of the species 
depend. The cerebral system connects us with the external 
world in every thing that relates to sensation and volition, or 
mind ; the true spinal system, in every thing that relates to the 
appropriation of its materials, and of their expulsion; in every thing 
that, in those respects, relates to nutrition and reproduction. 
The true spinal marrow, as distinguished from the cord of 
eerebral, sentient, and voluntary nerves, with which it is insepara¬ 
bly blended in structure, is the centre or axis of a distinct system 
of excitor and motor nerves hitherto unknown to physiologists. 
VOL. XI. M m 
