82 Physiology. 



these lymph capillaries are continuous with larger but 

 still thin-walled lymph tubes, called lymph veins. But, 

 unlike the blood veins, the lymph veins do not gradually 

 increase in size by uniting. They suddenly form a large 

 tube, the receptacle of the chyle, beginning in the upper 

 part of the abdomen. (See Figs. 50 and 81.) 



The Main Lymph Duct. This tube soon narrows and 

 passes through the diaphragm, close to the spinal column, 

 and up along the column near the aorta, and empties into 

 the veins of the neck at the junction of the left jugular 

 and left . subclavian veins. This tube is the "thoracic 

 duct," or the main lymph duct. It has numerous valves, 

 and, like some of the smaller lymph veins, it presents a 

 beaded appearance, due to the filling and bulging out of 

 the valves. In the right side of the neck is a short right 

 lymph duct, which receives lymph from the right side 

 of the head, neck, and thorax, and from the right arm. 

 The lymph tubes, as a whole, are usually called the 

 "lymphatics." (See Figs. 50 and 81.) 



Valves at the Mouth of the Lymph Tubes. There are 

 valves where these lymph ducts empty into the veins which 

 prevent any reflow of liquid into the ducts, but allow the 

 lymph to pass freely into the veins. 



Muscle Fibers in the Walls of the Lymph Tubes. There 

 are plain muscle fibers in the walls of the lymph ducts. 



Lymphatic Glands. In its course the lymph passes 

 through many kernel-like masses, the lymphatic glands. 

 They may be felt in the armpits, in the groins, and some- 

 times in the neck. Lymph contains corpuscles which are 

 considered the same as the colorless blood corpuscles. It 



