354 ABSORPTION. 



duct, which finally empties its contents into the blood- 

 stream at the junction of the internal jugular and sub- 

 clavian veins of the left side. There is a smaller duct on 

 the right side. In some part of their course all lymphatic 

 vessels pass through certain bodies called lymphatic glands. 

 The lymphatic vessels of the intestinal canal are called 

 lacteals, because, during digestion, the fluid contained in 

 them resembles milk in appearance ; and the lymph in the 

 lacteals during the period of digestion is called chyle. 

 There is no essential distinction, however, between lacteals 

 and lymphatics. 



Lymphatic vessels are distributed in nearly all parts of 

 the body. Their existence, however, has not yet been 

 determined in the placenta, the umbilical cord, the mem- 

 branes of the ovum, or in any of the non-vascular parts, 

 as the nails, cuticle, hair, and the like. 



The lymphatics and lacteals commence most commonly 

 either (i), in closely-meshed networks, or (2), in irregular 

 lacunar spaces between the various structures of which the 

 different organs are composed. The former is the rule of 

 origin with those lymphatics which are placed most super- 

 ficially, as, for instance, immediately beneath the skin, or 

 under the mucous and serous membranes ; while the latter 

 is most common with those which arise in the substance of 

 organs. In the latter instance the small irregular channels 

 and spaces from which the lymphatics take their origin, 

 although they are formed merely by the chinks and cran- 

 nies between the blood-vessels, secreting ducts, and other 

 parts which may happen to form the framework of the 

 organ in which they exist, yet have a layer of epithelial 

 cells to define and bound them, the cells resembling those 

 lining the lymphatic vessels.* 



By some, the lymphatics and lacteals are believed to 



* See Dr. Sharpey's Article, "Lymphatic System," in Quain's 

 Anatomy, yth edition. 



