DEE. UROGENETAL SsysT KM. 
By A. Francis Drxon. 
THE URINARY ORGANS 
The kidneys, or glands which secrete the urine, are a pair of almost symmetric- 
ally-placed organs, ‘situated in the posterior part of the abdominal cavity, on 
either side of the vertebral column and opposite its lowest movable portion. The 
fluid secreted by the kidneys is received into the upper expanded portions of two 
long tubes—the ureters—and is by them conducted to the bladder, which is placed 
within the pelvic cavity. From the bladder the urine is passed, during micturi- 
tion, along the urethra to the exterior. In the male the urethra is a relativ ely 
long passage, and traverses the prostate gland and the whole length of the penis; in 
the female it is a short tube, and opens on the surface just. above the vaginal 
orifice. 
THE KIDNEYS 
The kidneys, when removed from a fresh subject, present a bean-shaped contour. 
They are of a dark brown-red colour, and each is surrounded by a thin glistening 
capsule (tunica fibrosa), which gives to the whole organ a uniformly smooth sur- 
face. The kidney is not a solid body, but contains a cavity called the renal sinus, 
the opening into which is termed the hilus (hilus renalis). The hilus is 
situated on the inner and anterior part of the kidney. Each kidney measures 
about 45 inches in length, 2 inches in width, and about 14 inch in thickness, 
and is placed so that its long axis is nearly vertical The weight of the 
adult kidney is about 44 ounces. In the freshly-removed kidney the upper and 
lower ends are smoothly rounded, and the wpper end (extremitas superior) is usually 
a little more bulky than the dower (extremitas inferior). The outer border (margo 
lateralis), which is opposite to the hilus, is rounded and convex, while the inner 
border (margo medialis), on which the hilus is placed, is concave from above down- 
wards. These two borders separate the anterior surface (facies anterior) from the 
posterior surface (facies posterior) of the kidney. ° 
The capsule which envelops the whole organ, is continued over the lips of 
the hilus into the interior of the kidney, and lines the walls of the kidney 
sinus. The vessels and nerves of the kidney pass through the hilus to enter 
or leave the sinus, within which they break up into branches. These branches, 
piercing the wall of the sinus, enter the solid substance of the kidney. The upper 
expanded portion of the ureter also leaves the sinus through the hilus. 
Position of the Kidneys.—The precise level of the kidney in the abdominal 
cavity is subject to a considerable amount of variation, and also it is usual to find 
a difference in the levels of the right and left kidneys of the same individual. Most 
frequently the left kidney is on a higher level than the right, but in many cases 
the kidneys occupy the same level; or the more usual condition is reversed, and the 
right kidney is a little higher than the left. 
If a line be drawn round the body at the level of the lowest part of the thoracic 
