30 The Anatomy of d HORSE. Chap. III. 



without a manifeft Violence to Nature ; fo that it feems 

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

 further than that we can, in Ibme nieafure, help ourfel'/es 

 in Accidents which may happen to thole Parts, which 

 cannot but occafion Pain as often as the Lungs and Cheft 

 are extended or deprelVd, if we fhoiild let them have their 

 full Liberty. 



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

 Air which they perpetually draw iii, they invigorate the 

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

 Life. And this will appear reafonable, when we confider 

 that the whole Mafs of Blood takes its Courfe through the 

 Lungs, before it is detach'd into any other Part of the 

 Body ; fo that during its Progrefs there, it is not only 

 purged from many of its thinner Impurities, which vilibly 

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

 from its groller Parts, which by Expedoration are dif- 

 charged through the Pipes of the Afperia Arter'ia, And 

 as the Blood-veiieis 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, mull 

 be very much heated by the Perpetuity of its Motion. 

 Ihe Thymus. , "^'''"S *j,s given a (hort Account of 

 ^ the Heart and Psricardtu?n^ as alfo of the 



Lungs and Windpipe, together with tlieir feveral Ufes, I 

 fhall, 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 uppermolt Part oi xhz 

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

 Infide. 



J jj. Its Ufe is to p'event the two large 



•^^' Branches of the /cr^^f and Cuva from be- 



ing hurt by the fharp Edges of tliefe Bones in their Paf- 

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

 (there being no Veiiels or excretory Ducts vifible 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-vefTels become the more nervous 

 and flrong, and therefore not in fuch danger of being 

 abraded. 



§.IV. 



