38 The Anatomy of aWOKSV.. Chap.1V. 



or Arch which rifes between the Brain and the Medulla Ob- 

 longata y and ierves to bear up the upper Part of the Brain, 

 that it may not prefs too hard upon the fubjacent Parts. 

 iTf rrr r.j Now as to its Adion and Ufe, it is very 



Hhe Ufe of the . , r) • r i r»i •» 



Brain certain, the Bram, according to the Phiio- 



fophcrs Terms, is the chief Seat of the Ani- 

 mal Faculty^ as the Heart is the Fountain of the Vital. 

 The Animal Spirits being prepared out of \v^ Parenchyma^ 

 or marrowy Subllance, and from thence conveyed into the 

 Nerves, which communicate Senfe and Motion to all Parts 

 of the Body. 



Thefe Spirits are firft of all form'd out of 



*''*' ^' terial Blood, which is conftantly fent by the 



Heart to the Brain, where there are innumerable Twigs dif- 

 perfed, not only through its cortical or greyifh Subllance, 

 but alfo through its white and medullary Subftance ; fome 

 of which Twigs fpring from the P/^.v«; Choroides -^Vi^ 

 Reie Mirahile above defcribed, and others from the Ca- 

 rotids l\\tmk\\'ts immediately. The fuperfluous Serum 

 is feparated by the Glands ; and that Portion of the Blood 

 which is not changed to animal Spirits, is taken up by the 

 Veins, and returned back again from whence it came. As 

 foon as thefe Spirits are elaborated, or rather, as foon as 

 the Blood has undergone fo many different Mortifications 

 and Changes in the capillary or hair-like Veflels of the 

 Brain, as to r(^nder its Particles fine enough to pafs through 

 the inner medullar Subllance, they then enter thofe Fibres 

 which compofe it, and feem to be no other than a large 

 Bundle of TubuU or little Pipes, which (if the Comparifon 

 may beufed) fomewhat obferve the fame Oeconomy with 

 hole of the Kidnies, which pafs from the external glandu- 

 lar Parts to the Caruncula Papiilare, Thefe little Particles, 

 or rather Spirits, are conveyed by the aforefaid Tubuli to the 

 upper Proceffes of the Medulla Oblongata^ to wit, the Cor- 

 pra Striata^ Nates^ and Te/Jes, ^c. and are there emptied 

 into the Nerves, whofe inner Subllance is white and iibrous, 

 like the Medulla from whence they fpring. 



fTieir Ufe ^^^^^ ^^^^ ^'^^^ Account of the Formation 



•"'" /.* of the animal Spirits, the next Thing that 



occurs, is in what Manner they become the Inftruments of 

 Senfe and Motion. In order to give the Reader a general 

 Idea of this, which is as much as can be done in fo fmall a 

 !Tr(?itifejit will be necellary in the iirll Place,to confider the 



Subllance 



