CIRCULATORY AND LYMPHATIC SYSTEMS 281 



PART II 

 THE LYMPHATIC SYSTEM. 



429. The Lymphatic or Absorbent System is made up of 

 numerous vessels of various sizes, and small bodies, also of different 

 sizes, called glands, and is intimately connected with the circulatory 

 system. The absorbents originate in a very fine network communi- 

 cating with fine delicate tubes, which are more numerous than the 

 capillaries of the bloodvessels, and are found in almost every struc- 

 ture of the body, being both deep-seated and superficial. The walls 

 of the larger vessels have three coats, and, internally, they are 

 supplied with valves which give them a beaded appearance when 

 distended. 



430. A number of the smallest of these absorbent vessels (afferent 

 vessels) will be found running to the glands. These are present in 

 almost every portion of the body, and are of various sizes, being 

 usually named after the region in which they are found — for instance, 

 the mesenteric glands in connexion with the intestines, and the bronchial 

 glands associated with the lungs. These glands give off other vessels 

 {efferent vessels), which are slightly larger, and these again pass to 

 other glands, and so on, until they end in one or other of the two 

 large trunks — i.e., the thoracic duct and the right lymphatic vessel, the 

 former being the larger of the two. 



431. The Thoracic Duct, a vessel which carries a mixture of 

 both lymph and chyle. The lymph is a colourless fluid that is 

 absorbed from the various tissues of the posterior portion of the body 

 and hind extremities, also from the left side of the head, neck, thorax, 

 and left fore-leg. The chyle is a milky fluid that is prepared during 

 the process of digestion, and is taken up by the lacteals or lymphatic 

 vessels and carried to the receptaculum chyli, a large vessel or 

 reservoir situated in the lumbar region between the posterior aorta 

 and venae cavae, wherein it mixes with the lymph, and is then conveyed 

 by the thoracic duct into a vein near the heart (par. 223, Nos. 7 and 8) 



