40 TIIE HEART; ITS SHAPE-PULSATION. 



they take place near its thin extremity, the common natural process is, that the 

 part of the liver attaches itself to the gut, and the offensive matter will then 

 slough off into the intestine, and come away by stool : a partial cure is the 

 consequence : not produced by medicine acting upon the part, as is very clear, 

 out by a common natural effort, aided by a more vigorous and healthy state 

 of the blood than when the disease was engendered. To assist the circula- 

 tion in regaining this state is clearly the duty of the medical attendant, and is 

 the only manner in which he can be of any service to the animal in restoring 

 it to health. 



40, Inihe lungs, then, does the blood receive from the air its invigorating 

 principle, and no sooner does this take place, than it drops into another shor 

 blood-vessel (a vein), and, by it, is conveyed again to the heart : not the same 

 small chamber on the right side, of course, but to a similar one on the left 

 side. Here the contractions go on as before mentioned, only that the blood 

 differs in quality ; this being now properly fitted to promote the purposes of 

 life, and for imparting the vital principle, occasioJis the heart to assume that 

 twisted shape we see in some animals, while in others whose bodily exertions 

 and arterial functions are less laboured than those of the horse (the sheep's for 

 example) it is more round : and, indeed, the heart of this last mentioned ani- 

 mal is, from this circumstance, usually termed, in the London district, a "round 

 heart." Out of the small chamber on the left side is the blood driven through 

 a valve, as before, into the large chamber of the same side; which in its turn 

 contracts, with much force, upon its contents, expelling the same into the great 

 artery. This periodical rushing of the blood into the arteries, imparts to these 

 vessels a motion we term pulsation, whereby the blood is propelled forwards, 

 to the remotest parts of the body. Lessening in size, and increasing in num- 

 ber, the branch-arteries, which receive this blood, become more sensitive as 

 they are farther removed from the heart, and afford us, at certain places, the 

 means of ascertaining by the touch the degree of heat at which may at any 

 time be the state of the animal's blood ; the contractions of the heart being 

 regulated, in quickness and force, by the degree of stimulation the heat of the 

 blood may occasion it. This is termed the irritability of the heart, and the 

 medical test of which I sj^eak, is called " feeling his pulse." Even in the tail 

 may this contractile power of the arteries, and its effects, be seen to advan- 

 tage ; when a colt is being docked, the blood squirts forth with frequent gushes, 

 answering in a tolerable accurate manner to the state of his pulse, although 

 the artery at that remote part is very small. But the blootl that is so changed 

 in the lungs, as 1 have just said, is still found to contain certain parti- 

 cles or properties, which would render it unfit for the purposes to which it is 

 to be applied, or those particles are required to effect certain purposes else- 

 where in the system. Accordingly, the major part passes into the liver, there 

 to be refined of its bitterness ; whilst a portion is attracted to the kidneys, 

 where it leaves its saline qualities, that pass ofi' by staUng, as the former is 

 voided by dunging. See " Liver," farther onwards. 



4L These purposes, however, are not always effected alike regularly, from 

 several causes. Frequently, the blood comes to those organs in a state too 

 vitiated for their utmost activity to cleanse; sometimes a diseased state of the 

 blood, at others, languor of the parts, indispose them to the performam-e of 

 their functions, and the blood is suffered to circulate, filled with humours that 

 war with the constitution, and form what is termed " constitutional disease," 

 or predispose him to receive disorders of varied malignity, according to cir- 

 cumstances. I shall come to advert to this point when, shortly, the liver and 

 kidneys claim our attention; but, the chie'est cause of disorders incident to 

 the animal by reason of defective liver, is the great exertions he is put to, and 

 iJieconsequent rapidity of thecirculation, whereby the blood is propelled through 



