1444 



THE DUCTLESS GLANDS 



he arrives at the physiological conclusion that the thymus is one source of the colored blood 

 corpuscles. 



Vessels and Nerves. The arteries supplying the thymus are derived from the internal 

 mammary and from the superior and inferior thyroid. The veins terminate in the two innom- 

 inate veins, and in the internal mammary and the thyroid veins. ^The lymphatics are of large 

 size, arise in the substance of the gland, and are said to terminate in the internal jugular vein. 

 The nerves are exceedingly minute; they are derived from the vagus and sympathetic. 

 Branches from the descendens hypoglossi and phrenic reach the investing capsule, but do not 

 penetrate into the substance of the gland. 



Artery. 



~~-*- ' Granular cells. 



Artery. 

 -Vein. 



Fein. 



. 



Artery. 



I_FiG. 1200. Minute structure of the thymus gland. Lobule of injected thymus from a calf, four days old, 

 slightly diagrammatic, magnified about 50 diameters. The large vessels are disposed in two rings, one of which 

 surrounds the lobule, the other lies just within the margin of the medulla. A and B. From thymus of camel, ex- 

 amined without addition of any reagent. Magnified about 400 diameters. A . Large, colorless cells containing 

 small oval masses of hemoglobin. Similar cells are found in the lymph nodes, spleen, and medulla of bone. 

 B. Colored blood corpuscles. (Watney.) 



Applied Anatomy .Sudden death "thymus death" with heart failure, and with or 

 , without acute respiratory embarrassment, has been recorded in a number of infants and children 



^in whom the thymus was enlarged, and the lymphatic tissues throughout the body showed 

 general hypertrophy, but who showed no other evidence of disease. Such deaths have often 

 occurred during the administration of anesthetics. 



frf Primary tumors of the thymus are rare forms of mediastinal newgrowth, and are usually 

 dermoids or lymphosarcomas. 



THE SPLEEN (LIEN) (Figs. 1201, 1202). 



The spleen is situated principally in the posterior portion of the left hypochon- 

 driac region, its upper and inner extremity extending into the epigastric region; 

 it lies between the fundus of the stomach and the Diaphragm. It is obliquely 

 placed, its long axis following the obliquity of the tenth rib. If the abdomen is 



