gence that, in consequence of an attack of diarrhoea, he had been induced to abandon the skim-milk treatment; but by whose advice, or with what result, I have not been informed, as all correspondence between us ceased from this date. The case clearly shows the great superiority of skim-milk over a meat diet in the treatment of diabetes, and equally illustrates the vacillation of mind peculiar to those who have long been subject to this malady.

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CHAPTER XII.

BRIGHT'S DISEASE-STRUCTURE OF THE KIDNEYS- -THE CIRRHOTIC OR GOUTY KIDNEY-THE WAXY KIDNEYTHE FATTY KIDNEY; INFLAMMATORY STAGE-FATTY STAGE TERMINATION IN

ATROPHY-CONDITION

OF

THE BLOOD-HYDRÆMIA AND DROPSY-URÆMIA AND COMA-INFLAMMATION OF THE SEROUS MEMBRANESHYPERTROPHY OF THE HEART-CAUSES OF THE DISEASE.

THE term Bright's Disease, as now understood, has a generic meaning, and includes different pathological conditions of the kidneys altogether distinct from each other in their origin, anatomical characters, and the phenomena with which they are associated. These pathological conditions are not produced by the introduction or developement of new and abnormal histological elements, but by the morbid alteration of the tissues of which the kidneys are composed: consequently, a correct knowledge of the different forms of Bright's disease is based on an accurate acquaintance with the

structure or histology of these organs. To this subject, therefore, I shall briefly refer.

Exclusive of the nerves with which they are supplied, the kidneys are composed of three distinct structures, namely, of tubules, lined with epithelium, of blood-vessels, having a complex and peculiar arrangement, and of a fibrous matrix, forming a skeleton, by which the tubules and blood-vessels are bound together and held in position; the whole being surrounded by a firm membrane or capsule.

The tubules may properly be considered as involutions of the mucous membrane of the pelvis of the kidney, into which they open and discharge their secretion. When they are traced from their openings, seated on the papillæ, or apices of the cones or pyramids dipping into the pelvis, they are found to pursue a direct course through the medullary substance of the organ. In this straight course they divide and subdivide about ten times, and very generally in a dichotomous manner, and at an acute angle, the branches thus formed pursuing a parallel course. In this manner the straight tubules by their ramifications form the cones or pyramids of the medullary substance, beyond the periphery of which no further subdivision takes place. On arriving at this point-the bases of the pyramids

the ultimate branches of the tubules begin to separate from each other, and to pursue a strongly convoluted, tortuous course, until each terminates in a large flask-like, spherical dilatation-the malpighian corpuscle; the cortical substance of the kidney is thus formed by the convoluted terminal branches and their globular extremities. The object of this tortuous arrangement evidently being to increase enormously the secreting surface of the gland. The walls of the tubules consist of a delicate, elastic, homogenous, basement membrane, lined with epithelium, which differs in its characters according to whether it invests the convoluted or straight portion of the tubules. In the convoluted tubules of the cortical substance, the epithelium is polygonal in shape, and glandular in character. It occupies about one-half of the diameter of the tubule, leaving the middle half free for the flow of liquid secretion. The office of these cells is evidently to secrete, or separate from the blood, the solid excreta of the urine; in their histological character, they closely resemble the glandular cells of other secreting organs. The convoluted tubules are, therefore, the proper glandular portion of the kidneys; their dilated extremities (containing the capillary tufts for the elimination of water) are destitute of lining.

epithelium, according to some authorities; but according to others' they are invested with a layer of the flattened tesselated variety. The straight and wider tubules, forming the medullary pyramids, are lined with flattened, or tesselated, epithelium, approaching, in character, to that investing the urinary passages. From this, it is evident that the straight tubules simply act as ducts, receiving the secretion of the convoluted, and pouring it into the pelvis of the organ.

In considering the blood-vessels of the kidney in a pathological point of view, I shall begin at a point where the branches of the renal artery, after having entered the cortical substance, ultimately ramify into terminal twigs. Each of these terminal vessels penetrates the distal extremity of a malpighian corpuscle, and is, therefore, termed an afferent vessel; within the corpuscle it divides into from five to eight branches, each of which subdivides into a tuft of capillaries, which are coiled and twisted together in various ways, but do not anastomose with each other. These capillaries form a dense rounded bunch or coil, which lies uncovered in the interior of the corpuscle; they again reunite,

1 For a discussion of this question, see Kolliker's Human Microscopic Anatomy. Lond. 1860, p. 408.