INTRODUCTION. 33 



miilating in the liver, or the obstracted ducts, it is at len^h taken up 

 by the vessels of those parts, and is carried over the frame. 



The bile is received into a kind of reservoir called the gall-bladder, 

 in which it is stored up for use: at the same time it is probably im- 

 proved in activity by the absorption of some of the fluid parts of it. 



The pancreas, or sweetbread, is a large gland, of a whitish colour, 

 adhering to the upper portion of the first small intestine, and which 

 secretes a fluid-like saliva, termed the pancreatic juice, that is poured 

 into the intestines, and assists in the process of digestion. Of the 

 precise nature, however, of this fluid, or the manner in which diges- 

 tion is promoted by it, we have no certain knowledge. 



The spleen, or milt, is a large and oblong substance of a dark pur- 

 ple hue, situated upon the paunch, being between it and the midriff. 

 Of the office discharged by the spleen we have no satisfactory infor- 

 mation. 



The Msorhcnts, — Every part of the body is continually changing. 

 The worn-out portions are dissolved, and taken up by the absorbent 

 vessels, and carried, like the chyle, into the circulation. They mingle 

 with and form part of the blood, and are converted again into nutritive 

 matter, or expelled by means of the liver, or in some other way. 

 These absorbents, or, as they are sometimes called, lymphatics, are 

 small transparent, elastic tubes, opening upon every surface, and 

 every portion of the body, external and internal. 



The trunks of the absorbents are arranged into two systems, one 

 of which lies near the surface of the body, and the other is more 

 deeply seated ; and both follow the course of the neighbouring veins. 

 They have valves like the veins, and pour their contents into the 

 circulation at the same point with the veins. 



The lymphatic inlands form a prominent part of the absorbent sys- 

 tem. They answer some valuable purpose, for every absorbent, in 

 performing its course, passes through one or more of these glands. 

 They are seen in the mesentery when the animal is opened, and they 

 can be plainly felt in the neck and under the jaw. 



The Blood. — The blood is incessantly circulating in the heart and 

 arteries and veins^, and through every part of the body, supplying 

 materials for its nourishment and growth, and for the various secre- 

 tions. The different parts of the system are constantly receiving and 

 appropriating to themselves those elements of the blood which are 

 proper to supply the waste they sustain from the necessary actions 

 of life ; conse(iuently the health and vigour of the body require a 

 new, daily, and liberal supply of fresh blood. That supply is in some 

 measure derived from tlie absorbent vessels generally, but chiefly 

 from the chyle, which is separated from the food in the process of 

 digestion. 



Blood, received into a vessel in the act of bleeding, soon separates 

 into two parts ; one of whicli is fluid, and called serum, the other 

 solid, and called red clot, or cake, or crassamenium. 



Scrum is the watery part of the blood, and surrounds the red clot. 



