[ 53 ] 
fingle Impulfe upon the fpinal Marrow of the 
Prog. 
XIV. 
Another Reafon for fuppofmg the Soul capable 
of chilling any Part upon which her Impulfe may be 
made, is, that if it was made in the Brain alone, 
there might be fome Impediment or Interruption to 
her Intention, produced in the Ganglions of the 
Nerves 5 which, fome Authors think, do the Office 
of fo many Brains, but which, more probably, ferve 
as fo many Fulcra or Stays to keep the Nerves firm, 
and to favour their further Directions to the different 
Parts of the Body. 
XV. 
Of Interftitial Air. 
The Air-Pump fhews us, that, in all flexible Bo- 
dies, fuch as Flefh, fmall Animals, and the like, there 
is a fufficient Quantity of Air, lodg’d in the Inter- 
flices between the mufcular Fibres and the Blood- 
veffels, &c. to refill the Preffure of the ambient Air 5 
which Preffure being taken off in the Air-Pump, this 
interftitial Air will expand itfelf, and fwell the Flefh, 
^Animal, dec. to an incredible Size. This may be 
confidered as a general c ^Equilibrium kept up be- 
tween the ambient Air, and that in an animal Body, 
for the Safety and Prefervation of the Animal: And 
thefe Air Globules, which we fhall throughout this 
Effay call interftitial Air , are conflantly in a middle 
State between their utmofl Contraction or Condenfa- 
5 tion y 
