406 THE COMPLETE GRAZIER. BOOK in. 



keeps in position, most of the abdominal organs. The great omentum 

 and the mesentery are portions of the peritoneum, which is really a 

 double sheet with its two faces in contact, the blood-vessels to and 

 from the stomach and intestines passing between them. In a horse of 

 average height the length of the small intestine is about 70 feet, and 

 its diameter is 1 inch to If. It opens abruptly, at the ileo-csecal valve, 

 into the large intestine. 



The large intestine consists of caecum, colon, and rectum. The 

 csecum, or blind-gut, is a very wide elongated sac, extending obliquely 

 downwards and backwards. Its length is a little over 3 feet, but it 

 has a capacity of 7J gallons, about twice that of the stomach. It 

 serves as a temporary reservoir for the large quantities of fluid ingested 

 by herbivorous animals. 



The colon, 10 to 13 feet long, has an average capacity of 18 gallons. 

 Its terminal part is a bosselated tube in which the fasces of the horse 

 are moulded into their characteristic shape before passing into the 

 rectum, whence they are expelled. 



The liver, the largest gland in the body, is wedged in between 

 the stomach and the diaphragm. It is made up of several lobes, 

 and is remarkable in the horse as possessing no gall-bladder, the 

 flow of bile taking place when required along the bile-duct, or ductus 

 choledochus. The healthy liver of a horse of average size weighs 

 about 11 Ib. 



The pancreas, or " abdominal salivary gland," weighs a little over 

 1 Ib. It is spread out on that portion of the mesentery near the com- 

 mencement of the small intestine. The spleen weighs about 2 Ib., 

 but it is sometimes three or four times its normal volume. 



URINARY ORGANS. The kidneys are imbedded securely beneath the 

 muscles in the region of the lumbar vertebra. They are kept in 

 position, partly by the cushion of fat on which they rest, partly by the 

 peritoneum passing beneath them, and partly by the pressure of the 

 digestive organs. The right kidney, which is beneath the last two 

 ribs, is more forward than the left ; the former weighs about 27 oz., 

 the latter about 25 oz. They differ also in shape. 



The urine, separated from the blood in each kidney, is continually 

 flowing along a tube (the ureter, right and left) into the bladder, which 

 is a reservoir from which the fluid can be expelled as occasion may 

 require. The horse's bladder is very thin ; its average weight when 

 empty is 1 Ib. Its exit tube, the urethra, is guarded by a sphincter 

 muscle at its junction with the bladder. The urine contains most of 

 the nitrogenous waste of the body. 



BREATHING ORGANS. The respiratory apparatus of the horse is of 

 a normal character. The nasal cavities are bounded by the nostrils, 

 the external skin of which is fine, thin, pigttiented, and often spotted. 

 Their lips are extremely dilatable, as may be especially noticed in the 

 case of high-bred horses after exertion or excitement. Horses and 

 other solid-hoofed animals can only breathe through the nose, the 

 soft palate at the back of the mouth being so extensively developed 

 as to prevent breathing through the mouth. The course of the air 



