zs The Jnatomy of allOKSE. Chap. Iir. 



Cavity of the Cheil, being divided into two Lobes, one 

 of which lies on the right Side of the Mediajiinum ^ and 

 the other on the left. 



They are compofed of the various Ramifications, or 

 Branchings of the Veins, Arteries, and Nerves, together 

 with the Windpide, the Extremities of whole Branches 

 are very finely wove together, fo as to form an infinite 

 number of little Veficlcs, or Air-bladders, refembling fmall 

 Grapes when they are extended, but not very perceiveable 

 at any other time. When an Animal fucks in the Air, 

 thefe little Feficulce or Bladders, are then dilated and full ; 

 and when the Air is emitted, as in Expiration, they be- 

 come empty. 



Th Wndi>'t)e '^^^ Windpipe, whofe Branches make up 



a great part of the Subilance of the Lungs, 

 is that great Chanel, which beginning at the Root of the 

 Tongue, defcends down the Throat, and, as foon as it 

 reaches the Lungs, divides itfelf into two large Branches, 

 one to each Lobe. Thefe fend off a great many Branches, 

 •which detach an infinite number of other Branches that 

 reach into all Parts, and whofe Extremities open into the 

 Veficula, or Bladders above defcribed. 'J "his Pipe is 

 called the Trachea, or Ajperia Arteria, from its rough- 

 nefs, which Name it obtains from the Throtle to the 

 Lungs ; but thofe Branches which it fends off into each 

 Lobe, are term'd its Brenchia. 



It is compofed of a double Membrane, which inclofes its 

 Circular Ritigs, the innermoft of which being mufcular, 

 made up of Itreight and oblique Fibres, it thereby con- 

 tracts and dilates itfelf in the Adtion of Breathing. Thofe 

 Rings do not quite encompafs the Trachea, or A/per a 

 Jrteria, but leave a fourth Part of the Circle wanting, 

 3eft they fhould hurt the Gullet whereon it lies, and occa- 

 iiofi Pain in fwallowing ; but after it divides itfelt into its 

 Bronchia, they go quite round every Branch of it, fo far 

 as is perceivable to the naked Eye ; and doubtlefs, hold 

 the fame form where its Branches are the moft minute 

 and fmall. Thefe Rings, being in a great meafure, carti- 

 laginous, indue the whole Windpipe, and all its Branches, 

 with a fort of Elafticity or Spring, whereby it ads in 

 concert with its membranous and mufcular Parts. 



The Blood- vefl'els, which alfocompofe a 

 'J^7 great par t of the Bulk of the Lungs,are partly 



'^'^'^ '' a Branch from the great Artery, but princi- 



pally 



