40 The Jnatomy of a UOKSE. Chap. IV. 



duced by the Determination of the Animal Spirits ; for 

 when any Creature goes to move, the Spirits are thought 

 to be detached in a more than ordinary Quantity into 

 thofe Parts which are to be put in motion. And as the 

 Arterial Blood always accompanies the Spirits, and is 

 equally determined with them, the Mufcles are thereby 

 fiird or emptied, according as the Will or Inilindt directs^ 

 as we {hall fee more fully hereafter. 



But before I leave this Subject, it may perhaps be expect- 

 ed that I fhould give fome Account of the Nature of ihofe 

 Spirits which are faid to Row in the Nerves, and are rec- 

 kon'd the principal Caufe cf Adion in them.. To fatisfy 

 thofe who have a Curiofity that way, I fhali only in brief 

 take Notice, that thefe are thought by fome to be of a vifcous 

 and clammy Nature, though compofed o^ very keen Parti- 

 cles: And this fort of Compolition they rhink is agreeable 

 to that Elafacity and Springinefs, which 13 obferveable in the 

 Nerves. Others have denied any fuch thing as a Juice to 

 be in the Nerves ; becaufe v/hen a Nerve is cut afunder, 

 there is no viiible Bore or Cavity in it; neither are there 

 any Pofuii or little Interftices perceivable in it. But it is 

 very certain, according to the common and unalterable 

 Laws of Nature, whereby all Bodies are made up of Parts, 

 and thefe alfo made up of other Parts, they mxuft therefore 

 have Interftices, though they be imperceptible ; and that 

 Juice which flows in them, whether between thofe hiter- 

 fiices only, or any other way, tho' it be alfo imperceptible, 

 yet it is that v»'hich we not improperly denominate the 

 Animal Spirits. Though we can fiiy but very little more 

 than this, that it is the molt fubtle of all the Juices which 

 are to be met with in an Animal Body, and therefore the 

 beft fuited to the Services for which it is appointed. 



§. III. Of the Rife and Progrefs of the Nerves, 



Befides the Nerves, which arife from the Vertebra of 

 the Neck, Back, and Loins, there are nine Pair which take 

 their Origin immediately within the Skull. 

 o'i„ r a T, ■ The firfl are thofe which go to the Nofe, 



'Jhe nrft Pair , ^ r n , 1 A^r ^ -wt 



b^'Nert'es. ^"" ^^^ therefore called the Otjaofory Nerves, 



■^ ' and by fome the Mamillary Prccefj'es, be- 



caufe they are round at their end like a Pap : llicy rife 

 from the Shanks of the Medulla Oblongata^ betwixt the 

 Corpora Striata and the Chambers of the Optick Nerves^ 



from 



