GLANDS OF ABSORBENT SYSTEM. 133 



it inclines to the left, at the same time diminishing in size, 

 until it arrives at the third dorsal vertebra, where, passing 

 above the arch of the aorta, it comes into contact with the 

 gullet, between the left side of which and the pleura it lies ; 

 it then reaches the level of the point of union between the left 

 subclavian vein and left jugular vein, without any arch such as 

 there is in the human body. There are very few valves in the 

 thoracic duct of the ox. In man the lymphatics and lacteals 

 do not appear to reach the great trunks without passing 

 through conglobate glands. It has been affirmed that in ani- 

 mals like the ox exceptions to this rule are very numerous. 



Lymphatic Duct The right lymphatic duct is a shorter 

 and smaller vessel than the thoracic duct. It is formed en- 

 tirely by the successive junction of lymphatic vessels, and does 

 not receive any lacteal vessels. It receives the lymphatics 

 from the right anterior extremity ; from the right side of the 

 head and neck ; from the right side of the chest ; from the 

 right half of the lung and heart ; and from the upper surface 

 of the liver. It ends in the angle formed by the right sub- 

 clavian vein and the right jugular vein, in a manner corre- 

 sponding to the termination of the thoracic duct. A lacteal 

 vessel, according to the most recent views, arises in a 

 villus of the intestine, by a plexus of minute tubes. Both 

 the lacteals and lymphatics are freely furnished with valves 

 resembling the valves of the veins. The mesenteric glands, 

 through which the lacteal vessels pass before reaching the great 

 trunks, closely resemble the lymphatic or conglobate glands, 

 called also lymphatic ganglia. A lymphatic gland is described 

 as varying from the size of a hemp-seed to that of a kidney 

 bean ; and as to shape, these glands are either round or oval. 



Absorbent Glands. An absorbent or conglobate gland has 

 an external coat formed of areolar, that is, of cellular tissue, in- 

 cluding, as usual, elastic fibres and their formative cells, and 



