It should be added that when the bladder is filled with a soft magma a catheter may be introduced through the whole length of the urethra to be used in pumping water into the bladder. This water is extracted through the same channel when it has been charged with the suspended solids by manipulations of the bladder with the oiled hand introduced through the rectum. CALCULI, OR GRAVEL, IN THE PREPUCE, OR SHEATH. This is usually a collection of gravel, or a soft, puttylike material which causes distinct swelling of the sheath and gives it a soft, doughy feeling when handled. It may be removed in part by the oiled fingers introduced into the cavity, assisted by manipulation from without, or a tube may be inserted until the end extends behind the collection and water pumped in until the whole mass has been evacuated. Should even this fail of success, the sheath may be slit open from its orifice back in the median line below until the offending matter can be reached and removed. In all such cases the interior of the sheath should be finally lubricated with sweet oil or vaseline. It is unnecessary to stitch up the wound made in the sheath. (See "Inflammation of the sheath," p. 155.) [Illustration: PLATE IX. KIDNEY AND MALE GENERATIVE AND URINARY ORGANS.] [Illustration: PLATE X. MICROSCOPIC ANATOMY OF THE KIDNEY.] * * * * * DISEASES OF THE URINARY ORGANS. DESCRIPTION OF PLATES. PLATE IX. Kidney and male generative and urinary organs. Fig. 1. Kidney of the ox. (From Handbuch des Vergleichenden Anatomie des Haus S‰ugethiere, vol. 7, 1890.) A, renal artery carrying blood into the kidney; V, renal vein carrying blood from the kidney back to the heart; H, ureter, the tube carrying the urine from kidney to bladder. It is formed by the union of a number of branches which begin as cups (calices), each inclosing the tip of a conical mass of tissue from which the urine excludes.