PHYSIOLOGY. 39 



in the horse there is simply one duct, which conveys the bile, 

 as already stated, into the duodenum, where it assists in the 

 process of chylification. 



Kidneys. Their office is to convey or secrete the super- 

 fluous fluids and excrementitious parts of the blood in the 

 form of urine. In man, the skin is the great outlet of the body, 

 and the kidneys are one of a secondary order ; but in some 

 animals, the kidneys are the principal parts concerned in car- 

 rying off the impurities of the blood. When horses are allowed 

 an unlimited quantity of hay and water, or when they are fed 

 on improper food, and the skin obstructed, the urine will be 

 voided in large quantities — thick, turbid, deficient in quality, 

 and having a peculiar stinking smell. From a cavity in the 

 centre of each kidney, a canal or tube proceeds, by which 

 the urine is conveyed into the bladder. These tubes are named 

 ureters. As the ureters enter the bladder, they pass forward 

 a short distance between its coats ; which course effectually 

 prevents the urine from flowing back into the ureters. The 

 urine is expelled by the muscular power which the bladder 

 possesses of contracting upon its contents. The horse's kid- 

 neys are readily affected by diuretic medicines, and many 

 valuable horses are ruined by the too frequent use of nitre 

 and rosin. These articles are indirect diuretics ; they cause a 

 large secretion of urine, but do not provide for the excretion. 

 In such cases, the bladder may be distended beyond its usual 

 capacity ; its fibres may become lacerated, and thus be in- 

 capable of contracting on its contents. Disease of the kid- 

 neys sometimes happens in consequence of excessive exertion, 

 or strain of the loins ; and sometimes peritoneal disease spreads 

 to^he kidneys. 



There are other glands scattered over the system, of equal 

 importance ; yet, in the present state of veterinary knowl- 

 edge, the author deems it unnecessary to refer to them. 



Anatomy and Physiology of the Eye. — The parts which 

 compose the eye are divided into external and internal. The 

 external parts are, first, the eyelashes, or cilia, which, in the 

 horse, can scarcely be reckoned more than one, there being 



