30 The Anatomy of n HORSE. Chap. III. 



without a manifell Violence to Nature ; fo that it fecms 

 to be chiefly natural, there being nothing in it voluntary, 

 further than that we can, in fome nieafure, help ourfelves 

 in Accidents which may happen to thofe Parts, which 

 cannot but occafion Pain as often as the Lungs and Cheft 

 are extended or deprefs'd, if we fliould let them have their 

 full Liberty. 



But befides the Ufe of the Lungs ih Refpiration, by the 

 Air which they perpetually draw in, they invigorate the 

 Blood, and render it more fit for the feveral Fundidns of 

 Life. And this will appear reafonable, when we confider 

 that the whole Mafs of Blood takes its Courfe through the 

 i-ungs, before it is detach'd into any other Part of the 

 !6ody ; fo that during its Progrefs there, it is not only 

 purged from many of its thinner Impurities, which vifibly 

 fly off from the Mouth and Nofe in breathing, but alfo 

 from its giofler Parts, which by Expedloration are dif- 

 charged through the Pipes of the Jfperia Arteria. And 

 as the Blood-veflels accompany the Windpipe in all its 

 Branches, the Blood itfelf is not only thought to be there- 

 by cooled, but at its return is believed to give a mode- 

 rate Temperament to the Heart, which, no doubt, mult 

 be very much heated by the Perpetuity of its Motion. 

 tr-, Tjiynius Having thus given a fhort Account of 



the Heart and Pericardium^ as alfo of the 

 Lungs and Windpipe, together with their feveral Ufes, I 

 Ihall, before I leave this middle Cavity, take fome Notice 

 of that large Kernel called the Thymus. It is fo called 

 from the Refemblance it bears to a Leaf of Thyme in its 

 fhape, and is lituated acrofs the uppermoft Part of the 

 Breaft, along the Collar-bones, covering them on the 

 Infide. 



J jj. Irs Ufe is to prevent the two large 



■' ' Branches of the Jorta and Cava from be- 



ing hurt by the fliarp Edges of thefe Bones in their Paf- 

 fage over them. And as it ferves to this Purpofe chiefly 

 (there being no Vellels or excretory Dufts vilible in its 

 Subftance) it is therefore much larger in Foals than in 

 grown Horfes, as it is indeed proportionally in all other 

 young Animals ; becaufe the older any Creature grows, 

 the Coats of the Blood-veflels become the more nervous 

 and ftrong, and therefore not in fuch danger of being 

 abraded. 



§.rv. 



