26 The Amtomy of a HORSE. Chap. Ill, 



flefhy Fibres, which, towards the Top, take their Directi- 

 on fpirally, like the Contortion of a Snail's Shell. 



It is faid to have a twofold Motion, which by Anato- 

 mifts is call'd StyHok and Diajlole ; or, in other Words, 

 its Contradion, when its Top is drawn towards its Bafis 

 or Bottom, for the Expulfion of the Blood into the Arte- 

 ries ; and its Dilation, when it is fill'd with Blood frorn 

 the Veins. As often as we feel the Pulfe beat, fo often is 

 the Heart contrafted ; it being the Contradion or Syjlok 

 of the Heart, which communicates that Vibration or Sul- 

 fation to all the Arteries. 



The Heart, befides its Pericardium above-defcrib'd-, 

 bath two Membranes, one that covers all its outfide, which 

 it derives from the outer Coat of the great Artery, and an- 

 other which lines it through all its inftde, which proceeds 

 from the inner Coat of the faid Veflel. It is ftored with 

 Fat tovyards its Bottom, which keeps it moid and glib, as 

 the Water in the Pericardium does the reft of its Subftance. 

 Its re/Tels Befides the large Veflels which empty 



' themfelves into it, and thofe which are 



conftantly fed by it, it has a Vein and two Arteries, which 

 are proper to it, and by which its Subftance is chiefly nou- 

 lifh'd. Thefe being wove all round like a Garland, are 

 therefore call'd Coronaria. It has alfo many fmall 

 Branches of Nerves, which fpring from the eighth Pair, 

 and fend forth other fmall Branches to the Pericardium, 

 hi Ventricks Within the Heart there are two Ventri- 



cles or Caverns, divided into a right and 

 left, by a flefhy Partition. The right of thefe Ventricles 

 is much the wideft, but not quite io long as the left, nei- 

 ther is it of fo compacfb a Subftance, or of fo great Strength, 

 the Septum^ or Wall, being peculiar to the left. The 

 Reafon of this difference fcems to be, becaufe the right 

 Ventricle fends the Blood only into the Lungs by the Pul- 

 monary Artery, whereas the left detaches it into all Parts 

 of the Body. The infide of thefe Ventricles is very cu- 

 rioufly made up, and intei^lin'd with feveral flefliy Pillars, 

 ibmewhat refembling the fmall Gothick Columns. The 

 Ufe of which feems to be chiefly for the better Commu- 

 nication of the Blood and Chyle, being, in every Contrac- 

 tion, wrung thro' them as thro' a Sieve. 

 The Valves of The large Veflels, which we have already 

 the large Vef- obferv'd to retain to the Heart, and likewile 

 fch. thofe by which it is conftantly emptied, have 



each 



