THE LYMPH 57 



THE LYMPH. 



The lymph is a clear colorless fluid contained in the lym- 

 phatic vessels and tissue spaces. It resembles plasma in gen- 

 eral appearance and does not differ greatly from it in com- 

 position. 



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 irregu- 

 larly shaped spaces between them. These spaces communi- 

 cate with each other and finally converge to the lymph ca- 

 pillaries. The intervals are called the "extravascular lymph 

 spaces!' (2) In certain situations, particularly in the ner- 

 vous centers, the small blood-vessels are completely sur- 

 rounded by and included in larger tubes, the "perivascular 

 lymph canals." These likewise pass on to the lymph capil- 

 laries proper. ( 3 ) The large serous cavities, like those lined 

 by the peritoneum, pleura, tunica vaginalis, etc., have large 

 numbers 'of lymphatic radicles opening abruptly into them, 

 or rather originating from them, and these may be consid- 

 ered as great extravascular lymph spaces. 



The course of the lymph is from the tissues to the sub- 

 clavian 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 lym- 

 phaticus dexter, which enters the right subclavian vein at its 

 junction with the internal jugular. The lymphatics from all 

 other parts of the body converge 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 receptaculum chyli. The lac- 

 teals pass through the mesenteric lymphatic glands on their 

 way to the receptaculum chyli. 



The distribution of the lymphatics needs no comment when 



