THE THYROID GLAND. 391 



and forms the calyces. The lower end pierces obliquely 

 the under surface of the bladder, and, after running 

 about three-fourths of an inch in the wall of the bladder, 

 opens at a posterior angle of the triangle at the base of 

 the bladder. 



THE SUPRA-RENAL CAPSULES. 



The supra-renal capsules are ductless glands situated 

 behind the peritoneum, upon the kidney. They are of a 

 yellowish color, flattened, weigh about two drachms, and 

 measure about one and a half inches in length. They 

 have an outer cortical and an inner medullary portion. 

 The cortical substance consists of columns perpendicular 

 to the surface ; the medullary portion is of a dark-brown 

 color and pulpy consistence. 



The cortical columns are derived from the inner sur- 

 face of the fibrous capsule which invests the gland. 

 They are abundantly supplied with vessels. 



THE THYROID GLAND. 



The thyroid gland is placed like a saddle across the 

 upper part of the trachea ; it presents the two lateral 

 lobes and the isthmus ; it is brownish-red in color, and 

 weighs about one and a half ounces. The isthmus covers 

 the second and third rings of the trachea ; it is about one- 

 half to three-fourths of an inch wide ; the lobes are two 

 inches long and about one inch in width ; the gland is 

 inclosed in a fibrous capsule, which sends inward sup- 

 porting septa, dividing the gland into lobes and lobules; 

 the lobules are formed of closed vesicles, lined by a 

 single layer of cuboidal epithelium. The vesicles are 

 filled with a gelatinous fluid, containing disintegrating red 

 corpuscles and free haemoglobin. The blood-capillaries 

 and lymphatics form extensive plexuses around the 

 vesicles. The thvroid has no duct, 



