OUTLINE OF THE STRUCTUEE OF THE HORSE. 67 



secretes the pancreatic fluid, which flows through its own duct 

 into the small intestines through a valvular opening common 

 to the hepatic and pancreatic ducts. (See g, in cut of the 

 stomach.) In its uses, the pancreatic fluid is apparently sim- 

 ilar to the saliva. It contains a large proportion of albumen 

 ^nd some free acid. 



THE SPLEEN. 



< This organ, often called the melt, has no excretory duct, 

 and, hence, can hardly be called a gland. It lies along the 

 left side of the stomach, to which it adheres very closely. 

 It is long; at one end broad and thick, and at the other 

 tapering almost to a point. In color, it is of a bluish brown. 

 It has a spongy consistency, being composed of numerous 

 cells, over which are spread thousands of minute vessels. 

 Physiologists have not been able to positively demonstrate 

 the uses of this organ. It is believed, however, " to perform 

 the office of a reservoir for the blood required by the stom- 

 ach, with which it is closely connected by a set of vessels, 

 and also to efiect some change in the blood itself." 



THE URINARY ORGANS. 



These embrace the kidneys and the bladder, with the dif- 

 ferent ducts and passages tl:^t are connected with them. 



The kidneys secrete the urine. They are two glandular 

 organs, whose function it is to rid the system of the element 

 called urea, which is that principal constituent of the urine 

 that, if not excreted, would act as a deadly poison in the 

 blood. In the horse they are of immense size, and are sit- 

 uated under the loins, the right kidney lying under the liver, 

 and somewhat forward of the left, which is placed back of 

 the stomach. Each of them is supplied with a large artery, 

 which furnishes blood not only to the kidneys themselves, 

 but likewise to all the urinary organs. Like all other glands, 

 the kidneys abound in minute capillary vessels, where the 

 functions of excretion are carried on. The amount as well 

 as the quality of the urine which they secrete varies greatly, 



