Attached to the atlantal, and partly to the mcsial side of the kidneys, arc found two bodies of a dark yellow co lour, and of an irregular, flattened form. Their size varies, but in the adult they are generally about two fingers' breadth in length. These, from their glandular appearance, have been called renal, or suprarrnal glands ; and, front the blackish fluid which they contain, atraln hary capsules. They are of a firm texture, slid a yellow ish colour, superficially, but of a softer consistence, and or a reddish brown in their central part. 1 fere there it sometimes a cavity, containing a serous blackish fluid, and lined with a delicate membrane. They are enve loped in the same cellular substance that surrounds the kidneys, and have a proper coat, which is thin, and ad heres firmly to the surface. They arc well supplied with arteries, have several veins, lymphatics, and nerves, but appear to have no excretory ducts.
The kidneys and urinary bladder are probably the only organs appropriated to the secretion and excre tion of the urine. The use of the renal glands is not known.
The urinary organs have not the same appearance and proportion in the fittus as in the adult. The kidneys have an irregular surface, and are composed of several distinct lobes ; the renal glands are almost as large as the kidneys themselves, and receive a considerable quan tity of blood; the urinary bladder, instead of being sphe rical, as in the adult, is of a lengthened form, extending almost to the navel, and its fundus is prolonged into a conical tube, called urachus, which passes between the umbilical arteries, forming the middle of the future tri ple ligament, which we have described as connecting the bladder with the navel. After birth, the kidneys gradually acquire the uniform external appearance which they are found to possess in the adult ; the renal glancL diminish till they become not more than 1-5th of their original size ; the bladder diminishes in length, becomes rounder, and gradually sinks within the peivis, scarcely arisims above the pubis, except when consi.iv rablv dis tended with urine. In very young children, the bladder is possessed of much more irritability than at most other periods of life, and the urine, from this circumstance, is seldom long detained. In old people, the kidneys lose the firmness which they formerly possessed, and gene rally become soft and flaccid, while the cellular mem brane that envelopes them is deprived of a considerable portion ol its rat. The urinary bladder sometimes loses min h ol its irritability, and being less excited by the stimulus of the urine, allosss this fluid to collect in an unusual quamity. Thus, Irom frequent distension, it is often found greatly enlarged. In some cases, however, the bladder becomes contracted, and its membranes thickened, cartilaginous, or horny.
The general appearance, and most of the physical properties of urine, are well known. Its specific gra vity is rather greater than that of water, varying from 1.005 to 1.033. When first voided, it has usually an agreeable odour, but this is gradually lost; and after having stood sonic time, the fluid acquires a peculiar fcetor Examined by chemical analysis, the urine is found to contain a great variety of ingredients, some of them of a peculiar nature. Water is the most bulky constituent, and it holds in solution or suspension, phosphoric acid, phosphates of lime, magnesia, soda, and ammonia ; carbonic acid, carbonate of lime, benzoic acid, muriatt s of soda and ammonia, sulphur, albumen, gelatine, a resinous substance, and three peculiar prin :;iples, one of which is called ro.s.acic acid, and the others uric acid and urea. See CHEM ISTR Y.
Numerous morbid appearances have presented them ,elves on examining the urinary organs after death. The peripheral membrane of the kidin ys has been found inflamed; the kidneys themselves scirrhous, ulcerated, affected with scrofulous tumours ; filled with hydatidg, or having within them calculous concretions. The sub qance of the kidneys is sometimes found preternaturally soft, at others unusually hard, or having earthy or bony particles dispersed through it. Frequently one kidney is found larger than the other ; in some cases there is only one, and in a few instances both kidneys are found to have grown together. The renal glands have been seen scrofulous, and sometimes ulcerated. The ureters ate frequently seen much dilated, their coats thickened, and sometimes a calculous concretion impacted within ;heir cavity.
The urinary bladder is often found in a state of in flammation or ulceration; it is sometimes discovered in a cancerous state, beset with fungous or polypous ex crescences, or has ing its coats thickened. Its cavity is sometimes divided into two, and, in a few cases, hollow appendages, or cysts, are found communicating ss ith it. Part of the bladder has been found valuing, and in these cases the ureters sometimes terminate near the navel; at others the dorsal side of the bladder is turned sternal, and the meters open a little above the pubes. One of the most common morbid appearances of the bladder is that of urinary concretions, or stones, either lying loosely within the cavity, or attached to the central membrane. In most cases these stones are single, but not unfre quently there are several found together. In the former case, the concretion is usually of an oval form, and smooth surface ; but in the latter the form is generally angular, and the surface more or less uneven. For a particular account of the appearances, and chemical analysis of In inary concretions, see the articles CHEMIS TRY and Sum; EN y.