C 27 ] 
(when mix’d with the Blood) to be capable of railing 
a Fermentation : This is the Animal Spirit. So that, 
when the Soul performs an Adi of Volition, there 
mull of Necefiity happen a certain local Agitation of 
animal Spirits in the Brain, from the great Union 
between the Soul and Body ; whereby the Beginning 
of fome Nerve receives an Impulfe, which is conti- 
nued to the Juices thro' its whole Length : And fo, 
from an Irritation at the Beginning of the Nerve, tke 
laft Drop of the nervous Juice is, by a gentle Vibra- 
tion, thrown out at the other Extremity, and al fo 
from the little Mouths of every other Nerve difperfed 
through the whole Mufcle in the fame manner, ac- 
cording to the Power of the Will. And as a Spunge 
fill’d with Liquor fuffers not a Drop to fall out, fo, 
fays our Author, altho' thofe little Mouths of the 
Nerves {in the Mufcle ) are always open; yet the 
Drops of the nervous Juice never fall from them, 
without an attual Impulfe or Concufiion ; becaufe 
the fpungy Subftance of the Nerves ferves them in- 
flead of Valves *. 
XXXVII. 
When therefore, fays he in his fifth Settion, by 
the Command of the Will, or from Nature's Cuftom 
(in involuntary Motion), innumerable Drops are 
thrownfout together from the Orifices of the Nerves, 
thro’ the intire Bulk of the Mufcle, which is always 
thoroughly moiftened with Bloody then theie fpiritu- 
ou$ 
* This is alfo taken from Borelli , where he fpeaks of a Nerve. 
•E Z 
