40 The Anatomy of a WOKSV.. Chap. 1\'. 



duced by the Determination of the Animal Spirits ; for 

 when any Creature goes to move, the Spiiits are thought 

 to be detached in a more than ordinary Qiiantity into 

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

 Arterial Blood always accorjipanies the Spirits, and' is 

 equally determined with them, the Mulcles are thereby 

 fiU'd or emptied, according as the Will or Inftin<^l direds, 

 as we (hall fee more fully hereafter. 



But before I leave this Subjed, it may perhaps be expeft- 

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

 Spirits which are laid to flow in the Nerves, and are rec- 

 kon'd the principal Caufe of AClion in them. To iatisfy 

 thole who have a Curiofity that way, I fhall only in brief 

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

 and ckmmy Nature, though compofed of very keen Parti- 

 cles: And this fort of Compofition they think is agreeable 

 to that Elafticity and Springinefs, which is obierveable in the 

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

 be in the Nerves ; bccaufe when a Nerve is cut afunder, 

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

 any Fonili or little Inter jlkei 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 muft therefore 

 have hiteijlices, though they be imperceptible ; and that 

 Juice which flows in them, whether between thofe Inter- 

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

 yet it is that which wc not improperly denominate the 

 Animal Spirits, Though we can hy but very little more 

 rhan this, that it is the moft fubile of all the Juices which 

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

 belt fuiled to the Services for which it is appointed. 



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



Befides the Nerves, which arifc from ihe Vertebra; of 

 the Neck, Back, and I>oins, there are nine Pair which take 

 their Origin immediately witliin the Skull. 

 77'/- firf} Pair '^^^ ^^ ^^^ (ho\c which go to the Nofc, 



vf Nerves. ^^^ aretlierefore called the O factory Nerves, 



and by Tome the Mamillary Proccfes^ bc- 

 caufe they are round at tlieir end like a Pap : 'I'hey rife 

 from the Shanks of the Medulla Oblongata., betwixt the 

 Corpora Striata ar.d the Chambers of the Optick Nerves^ 



from 



