[ i8 3 ] 
controulable by the will, we find peculiar nerves, 
namely the phrenic, which have no Ganglions fent to 
it from a great diftance. 
In propofing this as the probable ufe of Gangli- 
ons, lam far from thinking it entirely exempt from 
difficulties; but they are chiefly fuch, as arife from 
our imperfect knowledge of the nerves in general; 
a terra incognita, which remains to immortalize the 
name of fome future difcoverer in anatomy. It is 
well known, for inflance, that all the nerves fent from 
the fpinal marrow have Ganglions, where they fend 
off the branch, which communicates with the inter- 
coftals (/(’). Though this be true, it is mod probable, that 
thefe Ganglions refpedt the intercoflals, and only affiedt 
its nerves, leaving the other fibres fit and free for the 
conveyance of the commands of the will, as in fadt 
many of them are diftributed to mufcles under its 
power and diredtion. 
So likewife we are not to imagine, wherever the 
nerves unite, that their medullary fubftance either de- 
cuflates, or is fo intimately mixed, as is reafonably fup- 
pofed to be the cafe in Ganglions by mod anatomifts 
from Lancifi down to Haller. We know at leaf!, 
that this is far from being the cafe in the optic nerves; 
for though they unite, and were fuppofed to crofls 
each other, the contrary appears by obfervations made 
in the bodies of perfons, who were blind of one eye, 
from a fault in the optic nerve, the nerve of the 
affedted fide only being wafted, while the other was 
large and plump (/). And we may juftly infer the 
(X’) See the table of VieulTens. 
(/) See Monro’s Anatomy, p. 356; alfoN 0 23, of the nerves 
in general. 
plexi- 
