The right kidney, weighing 23-1/2 ounces, is shaped like a French bean, and extends from the loins forward to beneath the heads of the last two ribs. The left kidney (Pl. VIII) resembles a heart of cards, and extends from the loins forward beneath the head of the last rib only. Each consists of three distinct parts--(a) the external (cortical), or vascular part, in which the blood vessels form elaborate capillary networks within the dilated globular sacs which form the beginnings of the secreting (uriniferous) tubes and on the surface of the sinuous, secreting tubes leading from the sacs inward toward the second, or medullary, part of the organ; (b) the internal (medullary) part, made up in the main of blood vessels, lymphatics, and nerves extending between the notch on the inner border of the kidney to and from the outer vascular portion, in which the secretion of urine is almost exclusively carried on; and (d) a large, saccular reservoir in the center of the kidney, into which all uriniferous tubes pour their secretions and from which the urine is carried away through a tube g (ureter), which passes out of the notch at the inner border of the kidney and which opens by a valve-closed orifice into the roof of the bladder just in front of its neck. The bladder is a dilatable reservoir for the retention of the urine until the discomfort of its presence causes its voluntary discharge. It is kept closed by circular, muscular fibers surrounding its neck or orifice, and is emptied by looped, muscular fibers extending in all directions forward from the neck around the blind anterior end of the sac. From the bladder the urine escapes through a dilatable tube (urethra) which extends from the neck of the bladder backward on the floor of the pelvis, and in the male through the penis to its free end, where it opens through a pink, conical papilla. In the mare the urethra is not more than an inch in length, and is surrounded by the circular, muscular fibers closing the neck of the bladder. Its opening may be found directly in the median line of the floor of the vulva, about 4-1/2 inches from its external opening. GENERAL SYMPTOMS OF DISEASE.