THE LYMPH 5 7 



THE LYMPH. 



The lymph is a clear colorless fluid contained in the lymphatic 

 vessels and tissue spaces. It resembles plasma in general 

 appearance and does not differ greatly from it in composition. 



The Lymph Vessels. These vessels originate in at least 

 three different ways, (i) All cells may be said to be bathed in 

 lymph, being surrounded by that fluid lying in the irregularly 

 shaped spaces between them. These spaces communicate with 

 each other and finally converge to the lymph capillaries. The 

 intervals are called the " extravascular lymph spaces." (2) In 

 certain situations, particularly in the nervous centers, the small 

 blood-vessels are completely surrounded by and included in 

 larger tubes, the (l perivascu!ar lymph canals." These likewise 

 pass on to the lymph capillaries proper. (3) The large serous 

 cavities, like those lined by the peritoneum, pleura, tunica vagin- 

 alis, etc., have large numbers of lymphatic radicles opening 

 abruptly into them, or rather originating from them, and these 

 may be considered as great extravascular lymph spaces. 



The course of the lymph is from the tissues to the subclavian 

 veins, where it enters the vascular circulation. The lymphatic 

 vessels from the right arm and the right side of the face, head and 

 chest converge to form the ductus lymphaticus dexter, which 

 enters the right subclavian vein at its junction with the internal 

 jugular. The lymphatics from all other parts of the body con- 

 verge to form the thoracic duct, which enters the left subclavian 

 vein at its junction with the internal jugular. The thoracic 

 duct begins by a dilated pouch lying upon the second lumbar 

 vertebra. This pouch receives the lymphatic branches which 

 have converged from the lacteals, and is called the recep- 

 taculum chyli. The lacteals pass through the mesenteric lym- 

 phatic glands on their way to the receptaculum chyli. 



The distribution of the lymphatics needs no comment when 

 it is known that they receive the plasma which has been passed 



