212 THE HORSE. 



without the nausea which they produce ; but it causes more watery stools, 

 and consequently more debility. 



Ltnseed oil is an uncertain but safe purgative, in doses from a pound 

 to a pound and a half Olive oil is more uncertain but safe ; and castor 

 OIL, that mild aperient in the human being, is both uncertain and unsafe. 

 Epsom salts are inefficacious, except in immense doses of a pound and a 

 half, and then not always safe. 



The horse, and particularly the perfect horse, is occasionally subject to 



HERNIA OR RUPTURE. 



A portion of the intestine protrudes out of the cavity of the belly either 

 throuo-h some natural or artificial opening. In some cases it may be 

 returned, but from the impossibility of applying a truss or bandage it soon 

 returns again. At other times the opening is so narrow, that the gut, 

 gradually distended by faeces, or thickened by inflammation, cannot be 

 returned, and strangulated hernia is then said to exist. The seat of hernia 

 is either in the scrotum of the perfect horse, or the groin of the gelding. 

 The causes are violent struggling when under operations, over-exertion, 

 kicks, or accidents. The assistance of a veterinary surgeon is here indis- 

 pensable. 



THE LIVER. 



Between the stomach and the diaphragm, its right lobe or division in con- 

 tact with the diaphragm, the duodenum and the right kidney, and the 

 middle and left divisions with the stomach, is the liver. It is an irregu- 

 larly shaped, reddish-brown substance of considerable bulk, and performs 

 a very sins^ular and important office. 



We have already stated (p. 176) that the blood, which has been conveyed 

 to the different parts of the body by the arteries, is carried back to the 

 heart by the veins ; but that which is returned from the stomach and 

 intestines, and spleen, and pancreas, and mesentery, instead of flowing 

 directly to the heart, passes first through the liver. It enters by two large 

 vessels which spread by means of innumerable minute branches through 

 every part of the liver. As the blood traverses this organ, a fluid is sepa- 

 rated from it, called the hile. This is probably a kind of excrement, the 

 continuance of which in the blood would be injurious ; but while this is 

 thrown off, another important purpose is answered ; the process of digestion 

 is promoted, and particularly by the bile changing the nutritive part of the 

 food from chyme into chyle, and separating it from that which,, containing 

 little or no nutriment, is voided as excrement. 



The bile, thus formed, is in most animals received into a reservoir, 

 the gall-bladder^ whence it is conveyed into the duodenum (g-, p. 202) 

 at the times, and in the quantities, which the purposes of digestion 

 require ; but the horse has no gall-bladder, and, consequently, the bile 

 flows into the intestine as fast as it is separated from the blood. The 

 reason of this is plain ; a small stomach was given to the horse, that the 

 food might quickly pass out of it, and the diaphragm and the lungs might 

 not be injuriously pressed upon, when we require his utmost speed ; and 

 that we might use him with little danger compared with that which would 

 attach to other animals, even when his stomach is distended with food. 

 Then the stomach, so small, and so speedily emptied, must be oftener 

 replenished ; the horse must be oftener eating, and food must be oftener 

 passing out of his stomach ; and, consequently, there is no necessity for this 



