to the tesselated or pavement variety. They never appear in the urine under the ordinary circumstances of health. But in urine highly charged with uric acid, as in an attack of what is called gravel, the epithelium of these passages is shed sometimes in abundance. From the irritation of a calculus within the calyces, or imbedded in the pelvis or infundibulum of the kidney, or from any cause exciting pyelitis, these cells soon give place to exudation- and inflammation-corpuscles, and eventually to pus-cells. The epithelium of the bladder and urethra, and of the vagina in the female, is essentially protective, and consists of several layers of cells which exhibit the appearance of plates or scales with overlapping edges, and hence it is called the scaly or squamous epithelium. Individual cells, or a few cohering, forming a kind of scaly plate, are constantly seen in healthy urine-particularly in that of the female, the clusters of cells being derived principally from the vagina. In albuminous, and more particularly in purulent urine, this scaly epithelium is often present in abundance. The faint cloud which is often seen in healthy urine, and which hangs suspended in the fluid rather than is precipitated, is composed of urethral and vesical epithelium, with mucus-corpuscles more or less abundant, according to the quality of the urine. These latter corpuscles are formed in small proportion by all mucous surfaces, even in a state which cannot be considered otherwise than healthy.

In the early stage of renal disturbance accompanied by albuminous urine and dropsy, the epithelial gland structure of the renal tubes exhibits the simplest and earliest departure from the healthy or physiological type. It has apparently become somewhat larger, the nucleus is with difficulty seen, and the contents of the cell appear cloudy and granular. Here is the earliest manifestation of alteration of structure in the cell; and this alteration is accompanied by manifest embarrassment to the renal function. This alteration in the character of the renal gland-cell is in the great majority of cases preceded by evidence of grave disturbance in the equilibrium of the circulation within the organ, and proofs of blood escaping in greater

or smaller quantity from the Malpighian tufts are, in the acute form of renal dropsy, I believe invariable; sometimes hæmaturia is visible and palpable to the unaided eye. In other cases it requires the microscope to reveal the presence of scattered blood discs.

Within a very short period after the stage of congestion of the organ has appeared, the epithelial cells are thrown off, sometimes as isolated cells, or aggregated in twos or threes, but in most instances united together in a tubular form, constituting the epithelial casts so familiar to the eye of the pathological microscopist. But these cells are all imperfect. This throwing off of the epithelial gland-cell oftentimes in great abundance, constituting what Dr. George Johnson has characterised as a desquamative process, and has proposed to name this form of renal disorder desquamative nephritis, arises no doubt from the cell having undergone changes incompatible with its functions as a healthy secreting cell, and it therefore is cast off as effete and useless. This degradation of the cell from the physiological type we must conceive to arise from the nutritive process regulating the development of the succeeding cells from the germinal membrane (the basement membrane of Mr. Bowman) becoming embarrassed by the blood stasis. Cell after cell, so long as the embarrassment lasts, is defective and imperfect; they rapidly break up, or are thrown off entire, and to the attentive eye will afford indices of the favorable or unfavorable progress of the disease.

Concurrent with this alteration in the character of the renal epithelial cell, is the appearance of albumen in the urine, and a dropsical effusion of more or less extent and abundance throughout the tissues, more particularly apparent on the surface of the body.

It cannot be too strongly impressed as a pathological fact of importance, that healthy epithelial cells of the renal tubes or of the bronchial mucous membrane, are never cast off. It is only when from defective development, being useless for the purpose of the tissue or organ in which they are formed, that they are shed, and appear among the products of excretion.

CHAPTER III.

CAUSE AND SOURCE OF THE ALBUMEN IN THE URINE.

INTIMATELY Connected with the pathology of morbus Brightii, constituting as it does so important a symptom of the disease, and from its prominence constantly supplanting the name of our distinguished countryman, under the synonym of Albuminuria, is the question, whence is the albumen derived which gives to the urine its most significant character?

It is generally believed to drain through the Malpighian capillaries. It is affirmed that the serous elements of the blood percolate through these capillaries, which, in health, are supposed to furnish only the aqueous constituent of the urine. But if this were so, then the urine should contain not albumen alone, but the usual proportion of salts which make up the constituents of the serum of the blood. But this is impossible to prove, because the saline constituents of the urine of health do not materially differ, except in quantity, both relative and absolute, from those which are present in the serum of the blood.

Carbonates, sulphates, phosphates, chlorides of sodium and potassium, lime, and magnesia, in varying proportions, are present in both fluids. Some salts are found in the urine which are not present in the serum of the blood; but there are no salts in the serum which are not present in healthy urine. The chemical analysis of the urine, then, throws no light on the source from whence the albumen comes, and we still are left to conjecture, or to further investigation, to trace the channel through which so large a quantity of albumen is carried out of the system.

M. Robin has proposed a theory to explain the presence of albumen in the urine.

He considers that in health, albumen, as an excrementitious product, is decomposed in the blood by the functions of respiration; and that the nitrogenous residue of this combustion, urea and uric acid, are eliminated by the urine. Whatever, therefore, interferes with this metamorphosis of the albumen in the lungs causes its presence in the renal secretion. Thus, albumen is present in many pulmonary disorders-capillary bronchitis, phthisis, pneumonia, and certain cardiac affections.

M. Robin concludes that, when the respiratory process of combustion is too feeble to destroy the whole of the albumen which should be consumed in a given time, the general vitality is diminished; and thus, more or less albumen is allowed to pass into the urine: in fact, just so much as escapes transformation into urea and uric acid. The theory is ingenious and plausible; but it will not stand the test of clinical proof. The urine is albuminous in some cases of capillary bronchitis, in some cases of pneumonia, phthisis, and cardiac disease; even in some cases of emphysema and chronic bronchitis, but not in all. The hypothesis must fall, if (the assumed conditions being present) the proof fails even in one instance.

There are various physiological experiments and observations which, undeniably, favour the hitherto received opinion that the albumen of the urine is obtained directly from the blood. Bernard has shown that crude albumen injected into the jugular vein produces temporary albuminuria. And he further remarks that, in health, if the albumen of two or three raw eggs be swallowed, albumen will appear in the urine.

The liver is supposed to possess a powerful modifying agency on albuminous matters. Lehmann declares that 30 per cent. of albumen entering the liver by the portal vein, disappears in its passage through that organ, and cannot be found in the hepatic vein.

Dr. Parkes is inclined to the opinion that the liver plays an

important part in the development of albuminuria; he thinks, through some failure in preparation, either by the stomach or the liver, albumen enters the right side of the heart, still in a crude state, and in a condition similar to that introduced into the jugular vein in Bernard's experiment.

And he very pertinently adds, "many cases," I am inclined to say all," appear to be of blood origin, and among the many common antecedents of Bright's disease are circumstances of diet and mode of life impairing the processes of the stomach and liver. In how many cases," he asks, "although no liver disease was suspected during life, do we find the structure of this organ seriously diseased? In the history of Bright's disease there are many reasons for believing that the nutrition of the tissues is early and deeply affected."

No albumen is ever present in the urine, or indeed in any excretions from epithelial mucous membrane in the healthy or physiological state of the organs. The physiological chemist affirms that its presence indicates either disease of an excretory organ, or a morbid alteration in the composition of the blood (Lehmann, vol. i. p. 344), and clinical observations prove this. The presence of albumen in the urine, however, arises from many pathological causes, and it is no longer regarded as pathognomonic of only one form of disease. The diseases, however, in which albumen is temporarily present in the urine, are all of the type of what may be called blood diseases, and in which the integrity of the capillary circulation is manifestly disturbed. These comprise the various forms of fever, typhoid, typhus, small-pox, scarlet fever, diphtheria measles, erysipelas, acute rheumatism, pneumonia, and some others. It must be remarked, however, that albuminous urine is not always present in these cases, although it has been often observed. Albumen is also present in the urine whenever there is a mechanical impediment to the free return of blood from the kidneys through the renal veins into the cava, as in emphysema, chronic bronchitis, phthisis, and heart disease. It is found also occasionally in pregnancy, and disappears after the pressure