WORKS ON THE NERVOUS S VST EM. 
683 
the ingesta and egesta. I need scarcely observe, that there are 
external as well as internal parts which require the interstitial de- 
posit and re-absorption of the atoms of animal matter; it was to be 
expected, therefore, that there would be an external as well as in- 
ternal ganglionic and nutrient system. This we accordingly find, 
although it has never been so viewed or stated before. For the 
external organs, the ganglia, on the posterior roots of the spinal 
nerves, are probably destined ; for the head, the series of ganglia 
found upon and in connexion with the fifth or trifacial nerve ; 
for the lungs, stomach, &c. the pneumo-gastric ; for the internal 
viscera, the ganglionic system, commonly so called. ” 
“ Sir Charles Bell has, I believe, distinctly proved the differ- 
ence of function between the anterior and posterior spinal nerves, 
and between the respiratory and other nerves; brilliant discove- 
ries, which will, as long as anatomical and physiological science 
last, perpetuate and endear his memory : but there is no con- 
nexion between the function of sensation and the existence of a 
ganglion. The unequivocal sentient nerves, as the olfactory, the 
optic, the auditory, are without any thing very distinct of this 
kind; while the ganglionic nerves are without sensibility , or nearly 
so.” 
u The questions still remain — Why are the portio major, of 
the trifacial especially, and of the posterior spinal nerves, pro- 
vided with ganglia? The reply to these questions, and the ar- 
gument, may be stated thus: — 1. There is an internal nerve, for 
formation, nutrition, secretion, &c. — 2. This nerve is ganglionic. 
— 3. There are external organs to structures requiring nutrition, 
&c. — 4. There are also external ganglionic nerves. The inference 
is plain, that these constitute the external ganglionic sub-system; 
the fifth especially, abounds with ganglia. ” 
“ It is true, that the semilunar and external spinal ganglia 
differ in appearance from the ganglia of the sympathetic, as Sir 
C. Bell has well displayed. What is the nature of this dif- 
ference? To this question I find no reply in authors. It is 
plain, however, that the difference consists in their being alone 
plexic. The internal ganglionic nerve is purely nutrient ; its 
ganglia are simple. The external involve sentient, and, I believe, 
excitory nerves, with the nutrient ; they combine, therefore, the 
appearances of the plexus and of the ganglion. ” 
The distribution of the trifacial nerve to the parotid and sub- 
maxillary glands “ can only be for secretion also, the recur- 
rent of the fifth , discovered by M. Arnold, can only be distri- 
buted between the laminae of the tentorium — not for sensation, 
for it cannot be touched , nor for excited motion, but — “ for forma- 
tion and nutrition.” 
