The kidneys are two hard glands for the secretion of urine, placed in each lumbar region, just above the hips; they are outside of the peritoneum, or lining membrane of the abdomen, and surrounded with an abundance of fat. The right kidney is rather lower than the left, on account of the superposition of the liver. The length is about four inches, and the breadth two inches. The shape is oval, resembling a bean; the position upright, and the fissure (or hilum) is rather larger than the lower. It is covered by a strong fibrous capsule. The color is a reddish brown. Upon making a longitudinal secton of the kidney, as represented in cut, two different structures are presented. The internal is of a darker color, and consists of about fifteen of what are called the cones of Malpighi, which are arranged in three rows, the apex of each converging towards the hilum. This constitutes the medullary portion of the kidneys. The external structure is of lighter color usually, is extremely vascular, and of a granulated arrangement; it constitutes the cortical portion. The urine is formed in the tortuous tubes of the cortical substance, between whose walls are a number of small bodies called corpuscles of Malpighi.  At the apex of each cone is the papilla renalis, and in the centre of each papilla is a slight depression, called foveola. Each papilla is surrounded by a small membranous cup, called infundibulum, into which the urine is first received as it oozes from the orifices of the papillae. Four or five of these infundibula join to form a common trunk, called calyx, and the junction of about three calyces forms a common cavity, called the pelvis, which is conoidal in shape, and from which proceeds the ureter, the excretory tube of the kidney, which conveys the urine to the bladder. The ureter is a cylindrical tube of the size of a quill, with thin, extensible walls. It enters the inferior fundus of the bladder very obliquely, and opens by a very small orifice.

Just above the kidney, and reposing on its upper extremity, placed one on each side, are two small bodies, varying much in size, called the supra-renal capsules. They have no secretion, consequently no duct, but evidently perform important functions in foetal life, when they are much larger.