CHAP. II.] THE HEART, ITS ORGANIZATION. 115 



which difference we will show presently. So great 

 is the stimulus of this organ, that its contractile 

 power often exists long after the animal is dead, 

 and the arteries cease to flow : a phenomenon that 

 occurs when the horse is killed in full health, by 

 an accident, or otherwise, while in full possession 

 of its functions. In animals of much mettle or 

 courage the heart attains to a great size, that of 

 the famous horse Eclipse weighing 181bs. In some 

 horses, the vessels that nourish this muscular organ 

 lie exposed on the surface, with others they lie 

 wholly concealed ; a fact from which we have yet 

 found no opportunity of making any sure deduction, 

 but apprehend it may arise from the breed, and 

 conclude it must have considerable effects on the 

 individual's disposition. 



As the heart is the principal organ employed in 

 converting into blood what is drawn from the finer 

 particles of food sent into the system for that pur- 

 pose, as well as in renovating that which has been 

 exhausted of its vita!" principle in the circulation, 

 it may well be supposed full of small blood-vessels. 

 Four large ones meet at its thick end, and suspend 

 it, by being attached to the bones of the back and 

 ribs : two of them, bringing the dark vitiated blood 

 from the extremities of the fore-part and of the 

 hind-part, are veins ; the other two large vessels are 

 arteries, which, receiving the blood from the heart, 

 just now refined by the process of nature, convey it 

 with rapid contractions to every part of the system, 

 there to give fresh vigour, and to impart health to 



