76 PHYSIOLOGY. 



crevices in the connective tissues of the different parts of 

 the body. 



The Lymph Tubes. Opening out of the lymph spaces 

 are irregular passage ways called lymph capillaries, and 

 these lymph capillaries are continuous with thin-walled 

 tubes, the lymph tubes. These lymph tubes might be 

 called the lymph veins, since they join still larger tubes, 

 closely set with valves, similar to those of the veins. But, 

 unlike the blood veins, the lymph veins do not gradually 

 increase in size by confluence. They suddenly form a 

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

 upper part of the abdomen. 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." 



Lymph Spaces in the Frog. In dissecting the frog, the looseness 

 of the skin is very noticeable. The large spaces under the skin are 

 lymph spaces. Sometimes considerable lymph is found here, so that 

 in holding up a frog the sagging of the skin from the weight of the 

 lymph may be easily seen. 



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. 



