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the blood certain fluids; a number of glandular bodies (glands) 

 through, which the tubes frequently pass; and the fluids them- 

 selves, which are .lymph and chyle. 



LYMPHATIC VESSELS. 



These are called lymphatic vessels because they convey a clear, 

 limpid fluid; or absorbent vessels, because they absorb alimentary 

 matter. The absorbents of the chyle are called " lacteals." 



The tubes which form the lymphatic system are distributed 

 throughout the whole body and unite to form two large trunks, 

 the thoracic duct, and the right lymphatic vein, both of which 

 enter the venous system near the heart. The thoracic is the 

 largest and longest vessel and receives all the others, except those 

 of the right anterior extremity and right side of the head, neck, 

 and thorax. 



Lymph is a colorless fluid. Chyle is a milky fluid found in the 

 lacteals or lymphatic vessels of the intestines during digestion. 

 Since both the lacteals and posterior lymphatic vessels lead to the 

 great lymphatic trunk or thoracic duct, it follows that the lymph 

 and chyle become mixed. 



Through the excessively thin walls of the capillaries the fluid 

 part of the blood transudes (oozes) to nourish the tissues outside 

 the capillaries; at the same time fluid passes from the tissues into 

 the blood. The fluid, after it passes into the tissues, constitutes 

 the lymph, and acts as a stream irrigating the tissue elements. 

 Much of the surplus of this lymph passes into the lymph vessels, 

 which, in their commencement, can hardly be treated as inde- 

 pendent structures since their walls are so closely joined to the 

 tissues through which they pass, being nothing more than spaces 

 in the connective tissue until they reach the large lymph vessels, 

 which empty into the lymph glands. These lymph glands are 

 structures so placed that the lymph flovring toward the larger 

 trunks passes through them undergoing a slight change in struc- 

 ture. The glands give lymph corpuscles to the lymph, which are 

 identical with the white corpuscles of the blood. 



From the fact of this arrangement lymph glands are subject to 

 inflammatory diseases in the vicinity of diseased structures, 

 because infective material being conveyed in the lymph stream 

 lodges in th-e glands and produces irritation. The lymphatic ves- 

 sels contain great numbers of valves. 



