LYMPHATIC HEAKTS. 



381 



Terminations of lymphatics. The absorbent system discharges its contents 

 into the veins at two points, namely, at the junction of the subclavian and internal 

 jugular veins of the left side by the thoracic duct, and at the corresponding part of 

 the veins of the right side by the right lymphatic trunk. The openings, as already 

 remarked, are guarded by valves. It sometimes happens that the thoracic duct 

 divides, near its termination, into two or three short branches, which open separately, 

 but near each other ; more rarely, a branch opens to the vena azygos indeed the 

 main vessel has been seen terminating in that vein. Again it is not uncommon for 

 larger branches, which usually join the thoracic duct, to open independently in the 

 vicinity of the main termination ; and this is more apt to happen with the branches 



Fig. 439. PORTION OF SEROUS MEMBRANE OF DIAPHRAGM (PLEURAL) FROM THE RABBIT, TREATED WITH 



NITRATE OF SILVER AFTER REMOVAL OF SUPERFICIAL EPITHELIAL LAYER. (Recklinghausen.) 



c, c, cell-spaces of tissue ; d, d, commencing lymphatic vessels connected at b, 6, with the cell- 

 spaces. 



which usually unite to form the right lymphatic trunk. By such variations the 

 terminations in the great veins are multiplied, but still they are confined in man to 

 the region of the neck ; in birds, reptiles, and fishes, on the other hand, communi- 

 cations take place between the lymphatics of the pelvis, posterior extremities and 

 tail, and the sciatic or other considerable veins of the abdomen or pelvis. 



Lymphatic hearts. -J. Miiller and Panizza, nearly about the same time, but indepen- 

 dently of each other, discovered that the lymphatic system of reptiles is furnished, at its 

 principal terminations in the venous system, with pulsatile muscular sacs, which serve to 

 discharge the lymph into the veins. These organs, which are named lymph-hearts, 

 have now been found in all the different orders of reptiles and amphibia, and also in 

 birds, but not in any mammal. In frogs and toads two pairs have been discovered, a 



c c 2 



