PHYSIOLOGY. 
fi-Snftion in their powers of exciting the mufcles. The 
flighted touch on the portio dura convulfes the mufcles 
of the face, hut the animal gives no fign of pain ; while, 
by means of the branches of the fifth pair, which, if 
touched, give great pain, it is difficult to produce any 
degree of adlion in the mufcles. 
With reference to the immediate feat of fenfation, Mr. 
Bell finds, that the nerves of fenfation have their origin 
from the poderior portion of the fpine, or the cere¬ 
bellum; thofe of motion from the anterior parts of the 
fpine, or from the cerebrum. 
From thefe fafts w'a may beeafily led to infer, that the 
cerebrum is the feat of motion, the cerebellum of feeling. 
The experiments, however, which have been made by 
Rolando, (Saggio fopra la vera Struttura del Cervello, &c. 
Safari, 1809.) would feem to indicate that the reverfe of 
this is the cafe. But thefe experiments cannot be confi- 
deredofmuch value; for we obferve that, when Flourens 
repeated them, he found that neither the hemifpheres of 
the cerebrum nor of the cerebellum give motion, fince 
they can both be diced off in animals which dill remain 
danding, or, when irritated, walk. In faff, he fays, 
that the medulla oblongata, and tubercula quadrigemina, 
are the only parts of the brain capable of exciting con¬ 
tractions. Again, the correCtnefs of thefe experiments is 
fomewhat fhaken by the obfervations of Magendie, whofe 
experiments incline him to think, (Journal de Phyfio- 
logie, Avril 1823,) that, befidesthe parts jud named, the 
optic thalami are concerned in mufcular motion ; that 
the fanity of the cerebellum is.neceffary to progrejjlve 
motion, (fince ducks, when their cerebelii are mutilated, 
fwim backwards;) and that the corpora driata, when 
injured, excite animals to run forward. Ladly, a cafe 
related in the Bibl. Medicale feems to fliow the abfiirdity 
of one of Magendie’s opinions ; as it refers to a man 
who died of petrifaftion of the corpora driata, and who 
neverthelefs betrayed no unufual defire to move forwards, 
and in fad could not move at all. 
The conclufion from thefe contradifl ory datements 
feems to be, that the precife parts of the brain that pro¬ 
duce motion are unknown. One thing may be inferred 
with reafon, however, not only from the above experi¬ 
ments, which all agree as to this point, but from patholo¬ 
gical obfervation. It is, that the hemifpheres of the 
brain are not effential to motion. It is well known that 
acephalous fcetufes have furvived birth ; and Mr. Ham¬ 
mond (Medico Chirurg. Tranf. vol. xii. Part II.) has 
related a cafe, in which he found that the removal of a 
piece of the brain weighing two ounces (a procefs ren¬ 
dered neceffary to the delivery of a female) was unatten¬ 
ded for feveral hours witli any apparent lofs of cerebral 
function; for the child cried heartily, and breathed well, 
until hemorrhage at length killed it. 
Befides the effeCts of motion, fenfation, and fecretion, 
the nervous fyflem ads an important part in the evolu¬ 
tion of animal heat; a faCt which appears to Dr. W. 
Philip as corroborative of his opinion, that the nervous 
and galvanic fluids are identical ; and he endeavours to 
fliow, by experiment, that the gal vanic influence occafions 
an evolution of caloric from arterial blood, if fubjeCted 
to it as foon as it leaves the veffels, but that it produces 
no fuch effeCt on venous blood ; and alfo that the de- 
ftruCtion of any confiderable portion of the fpinal marrow 
is followed by a reduction of the temperature of the ani¬ 
mal. 
It remains to notice that curious and apparently- 
anomalous part of the nervous fyflem, the great fympa- 
thetic. According to Dr. Philip, “ in order that any one 
let' of organs may be fubjeCted to the influence of every 
part of another fet, it is neceffary thatfome very extenfive 
mode of nervous communication fliould exift between 
them. Such appears to be the objeCt of that complex 
fyflem of ganglionic nerves, of which the branches of the 
great fympathetic compofe fo large a portion. All the 
.organs whtch have mufcles of involuntary motion, and 
347 
which, as we have feen, are influenced by every part of 
the brain and fpinal marrow, receive nerves from a chain 
of ganglions, to which filaments of nerves from all the 
parts of the brain and fpinal marrow are fent. Thus 
the nerves iffuing from thofe ganglions are made up of 
filaments from an infinite number of fources, and tranfmit 
to the organs in which they terminate the united influence 
of all the nerves which the ganglions have received from 
the brain and fpinal marrow. Each ganglion may ac¬ 
cordingly be regarded as a fecondary centre of nervous 
influence, receiving fupplies from all the parts of the 
brain and fpinal marrow, and conveying to certain parts 
the united influence of thefe organs. On the other hand, 
as the mufcles of voluntary motion are to be fubjedted to 
the influence of only fmall portions of thefe central parts 
of the nervous fyflem, they receive their nerves diredtly 
from thofe parts; generally without the intervention of 
ganglia, and with comparatively few intermixtures of 
nervous filaments. The fyflem of ganglionic nerves 
appears to be quite as extenfive as that of nerves pro¬ 
ceeding dire 611 y from the brain and fpinal marrow.” 
Bichat maintains that the ganglions are centres of ner¬ 
vous influence, independent of the brain and fpinal 
marrow, and incapable of tranfmitting their influence; 
but he coincides with Philip’s opinion, that the great 
fympathetic derives its origin chiefly from the fpine, and 
not from the brain, with which it has only very {lender 
communications. 
But, befides thefe, the ganglionic arrangement of the 
fympathetic has given rife to a variety of conjedfures. 
By Willis, the fympathetic was regarded as executing 
fundfions of a nature diftindt from thofe of other nerves: 
iff, as it was intermediate between the conceptions of the 
brain and affedlions of the precardia. 2dly, as it commu¬ 
nicated between the adfions and paffions of the different 
parts of the body; the ganglia being fuppofed to afford 
receptacles for the animal fpirits. According to Window, 
the ganglia are nuclei, or feparate origins, of the fympa¬ 
thetic nerves, refembling little brains : this anatomiff: 
firft applied the name of fympathetic to this nerve; and 
he denies that it begins in the carotic canal, but ffates, on 
the contrary, that it fends branches back into it, for the 
purpofe of communicating with the fifth and fixth nerves. 
Meckel makes the ufe of the ganglia to be merely mecha¬ 
nical, viz. to divide the branches into fmaller twigs, and 
then into filaments; to enable thefe twigs to arrive at 
their deffiny by various diredlions; and, laftly, to unite 
many branches in one trunk. Scarpa gives to the gan¬ 
glia a three-fold ufe,—difuniting, intermingling, and 
again binding up in new fets : “ nervos nempe disjun- 
gendi, commifcendi, ac iterum colligandi.” This author 
endeavours to fliow that the ganglia are fo placed as to 
fend off, in fmalleft poffible Ipace, and with wonderful 
facility, branches of nerves to the contents both of the 
thorax and abdomen: thus, taking the fplanchnic, he 
would fain demonftrare that its origin is derived, firft, 
from threads of the intercoftal, and perhaps alfo of many 
fpinal nerves; fecondly, from filaments of fome of the 
dorfal nerves going from the fpine to the thoracic gang¬ 
lion ; and, laftly, from fibres of the fifth and fixth effedt- 
ing a communication with the brain. Lobftein naturally 
remarks, “Quam altiffima hujus nervi origo!” Scarpa 
concludes by giving it as his opinion, that all the vifcera 
fupplied from the ganglia of the fympathetic receives 
nerves compofed of filaments from many fources; fome 
derived from the brain, and others from the fpinal cord. 
According to Reil, the fympathetic conftitutes a pecu¬ 
liar nervous fyflem, diftindt from the brain, and called 
the ganglionic. This fyflem alone occurs in fome orders 
of animals; it alone fupplies the organs of nutrition, by 
which the wafted powers of life are renewed; and hence 
the name of vegetative , fometimes applied to it. It is 
found in the loweft fcale of animal exiftence, beginning 
with the mollufcEe, and gradually afcending to man. In 
the more perfedt fpecies, it is connedted with the cerebral, 
or 
