144 
Art. VI. A brief retftew of Dr. Marshall HaWs 
views on an Efcito-Motory System of IVcrves, 
by N. S. Davis, M. D. 
[Communicated to the Society.] 
Perhaps a correct knowledge of the physiology of no part 
of the human system is of more practical importance than 
that of the nervous tissue. For not only is it the seat of many 
of the most important and dangerous diseases which afflict 
mankind, but it is the chief instrument by which we gain a 
knowledge of all other affections. It regulates the motions 
of the limbs, the attitude of the body, the expression of the 
countenance ; by it we experience sensations of pleasure and. 
pain ; and under its influence we give vent to our feelings in 
articulate sounds. Hence its natural and healthy functions 
cannot be too carefully studied, nor too well understood; for 
notwithstanding the brilliant discoveries, and the consequent 
vast increase of our knowledge concerning the functions of 
different parts of the nervous tissue, it cannot be denied that 
the precise functions of many parts are still involved in ob- 
scurity. Among those parts requiring further investigation, 
perhaps none are more important than the respiratory system 
of Sir C. Bell, or the excito-motory of Marshall Hall, and the 
nerves of organic or vegetative life. The direct practical 
bearing of the views of Marshall Hall concerning his excito- 
motory system, renders a thorough examination of the facts 
on which those views are professedly based, an object of the 
first importance. 
The direct experiments which demonstrate the excito-motory 
phenomena are as follows : " A horse was struck with a pole- 
axe over the anterior lobes of the brain. It fell instantly, as 
if struck with a thunder-bolt; it was convulsed, and then re- 
mained motionless. It shortly began to breathe, and continued 
to breathe freely by the diaphragm. When lacerated or 
pricked with a sharp or pointed instrument, as a pin or nail, 
on any part of the face or surface of the body, it was totally 
motionless, manifesting no evidence of sensation or volition. 
When, on the other hand, the eye-lash was touched with a straw, N. S. Davis on Marshall Hall's Views. 
145 
the eyelid was forcibly closed by the action of the orbiculars; 
when the cornea was touched, the eye-ball revolved outward 
by the action of the abducens. When the verge of the anus 
was touched, the sphincter contracted forcibly. The upper 
part of the medulla oblongata was now destroyed ; there were 
violent convulsions ; the respiration ceased, and the eye-lid 
and eye-ball remained motionless on the application of sti- 
muli."* 
From this and similar experiments it is inferred, that the 
sentient and voluntary functions having been destroyed by 
the blow of the pole-axe, the contraction of the orbicularis, 
abducens and sphincter muscles must depend on a distinct 
system of nerves, having its centre in the medulla oblongata 
and spinalis. This is the excito-motory system of Hall. It 
embraces, first, the excitors, viz : the fifth or tri-facial; the 
pneumogastric ; and the posterior spinal nerves. These are 
distributed to the eye-lid, nostrils, fauces, face, larynx, pharynx, 
lungs, stomach, anus, cervex vesicse, cervex uteri, and the ge- 
neral surface of the body. Secondly, the motors, viz : the 
fourth, sixth, seventh, tenth, or pneumogastric ; spinal-acces- 
sory ; the phrenic ; the inferior external respiratory of Bell, 
and an undefined portion of the spinal nerves. These are 
distributed to the same part as the excitors, together with the 
whole muscular system.! The functions of this system are 
said to be, to regulate the acts of ingestion and egestion ; the 
functions of respiration, deglutition, defecation, urination, &c. 
and to give tone to the whole muscular system. The extreme 
branches of the excitors distributed to the mucous membranes, 
are also supposed by Dr. Hall to constitute the seat of the 
internal senses, or appetites; and he further attributes to this 
system of nerves, organic or nutritive functions.! These 
views of Marshall Hall are also embraced by Mr. Aston Key, 
Dr. Golding Bird, Dr. Bright, Dr. Whiting, and Mr. Grainger, 
who states that the centre of the system is in a distinct tract 
of the spinal marrow and medulla oblongata, lying between, 
* Hall on the Nerves, p. 28. 
t " " " pp. 25, 26. 
t " " " p. 46. 146 
N. >S*. Davis on Marshall Halts Views. 
and partly enclosed within the sensative and motor columns 
This minute anatomist alleges that he has verified the exist- 
ence of this column by actual dissection, and describes it as 
composed principally of grey substances, sending filaments 
to the posterior roots of the spinal nerves. These statements 
are said to be confirmed by the dissections of Samuel Solly, 
and disproved by those of Mr. Hilton, and many others.* That 
the spinal marrow contains in its interior more or less of a 
grey substance resembling the cortical, or cineritious sub- 
stance of the brain, is not doubted ; but that filaments can 
be distinctly traced from this into the roots of the spinal 
nerves, I have never been able to prove. And beside the ex- 
istence of such a column, possessing the functions attributed 
to it, is directly contradicted by the experiments of Dr. H. H. 
Smith of Philadelphia ;t and also by M. Magendie, Muller, 
Tiedemann, Dr. J. Reid and others. Indeed if we examine 
carefully the positions taken by the advocates of a distinct 
excito-motory apparatus, I think we shall find many of their 
conclusions unsustained by their premises, or by pathological 
facts. In the first place, they represent the spinal excitor 
nerves as distributed to the muscles of the eye; to the face, 
neck, and general surface of the body; while in the horse 
struck with the pole axe, the application of stimuli to the face, 
or any part of the surface, produced no effect except on the 
eye-lashes and verge of the anus. But why should not those 
branches of the tri-facial or fifth pair distributed to the face, 
exhibit the excito-motory phenomena as well as those distri- 
buted to the orbicularis palpebrarum, if both forme dparts of 
one and the same system ? Or if excitor nerves from the 
spinal marrow are distributed to the " general surface of the 
body," why will not pricking or lacerating any portion of 
this surface produce some effect as well as touching the anus ? 
Again, if the excito-motory system constituted the organic 
or nutrient nerves for the external parts of the body, as the 
ganglionic or sympathetic does for the internal, how could it 
* See a Report of the Proceedings of the Physical Society, Guy's 
Hospital, 1838. 
t Amer. Jour. Med. Sciences for 1837, No. 40. N. S. Davis on Marshall Hall's Views. 
147 
ever happen that the external parts of the body should be tole- 
rably well formed in the foetus, while the whole medulla ob- 
longata and medulla spinalis, and of course the whole centre 
of the excito-motory system, were wanting ?" And further, 
if the tri-facial or fifth pair are nutritive nerves, why does not 
the destruction of them at their roots prevent the future nour- 
ishment of the face ? True, it has been asserted on the au- 
thority of M. Magendie, that the destruction of the fifth nerves 
within the cranium destroyed the eye, from want of nutrition ; 
but this assertion has been abundantly disproved by a great 
variety of cases and experiments.* That the excito-motory 
apparatus is the seat of the internal senses, seems to be equally 
devoid of proof; for if we admit that the ganglionic or sym- 
pathetic system of nerves presides over the organic and nutri- 
tive functions, we should conclude, a priori, that the wants of 
the organs would be primarily indicated by these nerves, and 
consequently that in them are seated the internal senses. 
That the sense of hunger and thirst are not seated in those 
branches of the par-vagum or pneumogastric distributed to the 
stomach, is fully proved by the experiments of Dr. Reid, who 
states that animals often live several days after both the par- 
vagum and rccurrents are cut, with no other inconvenience than 
a very slow and laborious respiration. He further states, that 
the functions of the digestive organs and absorbents continued 
to be performed in a regular and healthy manner.! Another 
proposition of Dr. Hall is, that the excito-motory system gives 
tone to the muscles, and is the seat of nearly all our spasmo- 
dic and convulsive diseases ; but to suppose the numerous in- 
stances of convulsions from disease of some portions of the 
brain, to be caused only by pressure on or extension of the di- 
sease to the alleged centre of the excito-motory system, is to 
imagine what cannot be easily demonstrated. Besides, the 
morbid appearances of the spinal marrow in cases of tetanus 
are bv no means generally seated in the central excito-motory 
column described by Mr. Grainger. Indeed, if contraction of 
• London Medical Gazette, February. 1840. 
t Report of the Proceedings of the Medical Section of the British 
Association of Science, 1838. 148 
N. S. Davis on Marshall Hall's Views. 
the muscles in voluntary motions are induced by the nerves 
of voluntary motion, under the influence of the natural stimu- 
lus of the will, what simpler process of reasoning can be ima- 
gined, than to infer that irregular, spasmodic, or involuntary 
motions would be induced by the same nerves under the in- 
fluence of unnatural stimuli, or irritation. And instead of this 
sytem giving tone, to the muscles, we think facts will warrant 
the conclusion, that this quality of the muscular fibre depends 
entirely upon another cause, viz, the presence of well oxyge- 
nated or arterial blood ; else why does not contraction of the 
orbicularis palpebrarum, and other excito-motory phenomena, 
take place after the lungs are deprived of oxygen, or in a 
state of asphyxia? If the foregoing objections to the views 
of Marshall Hall are well founded ; if his excito-motory sys- 
tem of nerves neither control the functions of nutrition in the 
external parts, nor form the seat of the internal senses, nor 
give rise to ordinary convulsions and spasmodic diseases ; then 
is it reduced to nothing more nor less than the respiratory sys- 
tem of Sir C. Bell. 
There seem to have been two grand errors in the investi- 
gations of Hall and his followers. The first consisted in not 
duly considering the structure and functions of the internal 
ganglionic or organic nervous system ; the second in forgetting 
the experiments which prove the centre of the nerves of sen- 
sation and voluntary motion to exist in the medulla oblongata, 
and the consequent possibility of exciting contraction of the 
voluntary muscles, after the cerebral functions had been re- 
moved. 
Having devoted some attention to the anatomy and physio- 
logy of the organic, system of nerves, I am not only inclined 
to favor the views of Miller and Breschet, but think that future 
observations will show it to consist, like the sentient and vo- 
luntary system, of two sets; one for organic sensibility, in- 
cluding the internal senses ; the other, sanguineous, intestinal 
and organic motions. The first are distributed in the mucous 
membranes, the internal coat of the heart and arteries, where 
it receives the stimulus of oxygenated or arterial blood, &c. 
The latter are distributed to the muscles of organic or vegeta-