AFFLUENTS OF THE THORACIC DUCT. 637 



vessel. Their fusion generally takes place at the base of the heart, and 

 I have never seen them remain distinct throughout their whole extent, to 

 enter the vena cava separately. 



" Sometimes (Fig. 301) there emanates from the gland, at the entrance 

 to the thorax, a long canal which proceeds parallel to the first, and joins 

 it, after a retrograde course, near the pillars of the diaphragm. 



" The thoracic duct, double for the greater part of its extent, from the 

 time it leaves the snblumbar reservoir, occasionally ends by becoming 

 triple. In this case, the largest of the two canals is divided into two 

 branches ; then the three canals, after pursuing a certain course, all join at 

 the same point, or two are first united into a single conduit, into which the 

 third opens at a variable distance from the confluent of the first."' 



The affluents of the thoracic duct. — The lymphatic branches which 

 enter the thoracic duct are as remarkable for their number as their volume. 

 Some empty themselves into the sublumbar reservoir ; a few vessels open 

 into the great lymphatic vein of the thorax, and the others terminate in that 

 conduit, near its insertion into the venous system. 



The first, variable in their number, particularly the largest, are more 

 especially regarded as the roots of the thoracic duct. 



Ordinarily three are found, with a certain number of small accessory 

 trunks. One of the largest branches enters the posterior part of the cistern ; 

 very often double, and even multiple, it arises from an enormous group of 

 ganglia placed in the sublumbar region, around the posterior extremity of 

 the abdominal aorta and vena cava, and into which are collected all the 

 vessels of the posterior limbs, the pelvis, abdominal walls, and the pelvi- 

 inguinal viscera. The other two trunks reach the left side of the cistern, 

 and result from the union of the lymphatics which have their source in the 

 abdominal digestive organs; among these lymphatics, however, there are 

 some belonging to the parietes of the stomach and the parenchyma of the 

 liver and spleen, and which approach the right side of the sublumbar recep- 

 tacle, to open singly into that cavity. 



The affluents the thoracic duct receives on its course, proceed from 

 the viscera contained in the thoracic cavity, and from the walls of that cavity. 



Those which terminate at the anterior extremity of the duct are formed 

 by the lymphatics of the left anterior limb, and the left half of the 

 thorax, diaphragm, neck, and head. 



"We will now examine rapidly all the radicular branches of these 

 affluents. 



Aeticlb II. — The Lymphatics which form the Affluents of the 

 Thobacic Duot. 



These lymphatic vessels are divided into five groups. 1, Those of the 

 abdominal limb, the pelvis, abdominal parietes, and the pelvi-inguinal 

 organs • 2 Those of the abdominal digestive viscera ; 3, Those of the 

 organs 'contained in the chest; 4, Those of the thorax; 5, Those of the 

 head, neck, and anterior limb. 



> G Colin. ' Traite de Physiologie Compare'e des Animaux Domestiques,' vol. ii. 



summit of the anterior rena cava by two short branches It is double in Figure 300 ; 

 and in Fieure 301 it has a long branch that arises at the entrance to the thorax and 

 joins the duct, by a retrograde course, near the pillars of the diaphragm. 



