THE URIXARY ORGAXS 243 



fibrous coat immediately surrounding the kidney substance, each 

 organ is imbedded in a mass of fatty material, the adipose capsule 

 (capsula adiposa), and is also held in position by the peritoneum, 

 which is stretched across its ventral surface. 



1. If the peritoneum and adipose capsule are removed from the 

 left kidney, the external features and vascular connections may 

 be made out as follows: 

 (a) The general convexity of contour. 



(6) The renal hilus (hilus renalis), a concavity of the medial 

 surface of the organ. 



(c) The ureter, or duct of the kidney, a white tube passing 

 backward from the hilus. 



(d) The renal artery (a. renalis), arising from the abdominal 

 aorta and entering the kidney at the hilus. A branch of 

 this vessel, the suprarenolumbar artery (a. suprarenolum- 

 balis), passes to the body-wall in front of the kidney, giving 

 off a small suprarenal artery to the suprarenal gland. 



(e) The renal vein (v. renalis), leaving the kidney at the hilus, 

 and joining the inferior cava. 



The right renal artery leaves the aorta about one-half centimetre 

 in front of the origin of the left vessel, than which it is considerably 

 shorter. The two renal veins have similar relative positions, but the 

 distance between their proximal ends is a little greater. 



2. Divide the kidney, beginning the incision at the hilus and re- 

 moving the ventral half (Fig. 70). Examine the cut surface of 

 the dorsal half for the following: 



(a) The renal pelvis (pelvis renalis), a cavity within the 

 kidney, formed by the expanded funnel-like end of the 

 ureter, which is fitted into the renal hilus. A central cone 

 of kidney substance, the renal papilla (papilla renalis), 

 projects into the pelvis. 

 (6) The cortical substance (substantia corticalis) ; distinguish- 

 able as a narrow peripheral zone of the kidney substance, 

 (c) The medullary substance (substantia medullaris), forming 

 the central and medial portion of the kidney, including the 

 renal papilla. It is distinguished by its radial striations. 



