action of the acid upon the coloring matter of the blood, the inference will be that the case is an acute one, and that this large quantity of albumen has not been passing away from the kidney for any length of time. In very many of these cases, blood and numerous casts of the uriniferous tubes are present. Whenever blood escapes from any part of the kidney or mucous tract, albumen will, of course, be detected in the urine, for serum will obviously pass through fissures which permit the passage of leucocytes and red blood corpuscles.

In the majority of cases in which the presence of albumen in the urine is due to structural changes in the kidney, the vessels of the Malpighian tuft doubtless form the precise seat of the escape of albumen; but there are reasons for believing that serum sometimes passes from the capillaries surrounding the convoluted portion of the uriniferous tubes, and in some instances from those in contact with the straight portion ("Archives of Medicine," Vol. I, p. 300).

In chronic fatty degeneration of the kidney, there is often also a very large quantity of albumen, but the urine is pale and of low specific gravity. The history of the case, the appearance of the patient, the symptoms present, and the microscopical characters of the deposit, render it almost impossible to mistake a case of chronic fatty degeneration for one of acute inflammation of the kidney, caused by cold, or following scarlet or some other eruptive fever.

If the quantity of albumen was small, amounting merely to milkiness or opalescence when heat was applied, or nitric acid added to the urine, and especially if the urine was pale and of specific gravity 1.012 or lower, we should be led to conclude that the lesion giving rise to the escape of the albumen was chronic.

As a general rule, if, in a case of albuminous urine, the proportion of the urea to the other constituents of the solid matter turns out to be large, we should form a more favorable opinion than if the percentage of urea in the solid matter were very much less than in health. In the latter case, a great part of the renal structure would probably be involved; but in the former,

there would be reason to think the disease had so far only affected a small number of the secreting tubules. Many exceptions to these general statements are, however, met with in practice. In short, we must not permit ourselves to form an opinion upon the characters of the urine only, but must consider all the facts in connection with each individual patient. Patients have passed small quantities of albumen in the urine for many months, and yet it has entirely disappeared. In other cases, the progress of the disease is exceedingly slow. I have known a man pass urine of the character above mentioned for upward of twelve years; and I believe that in some cases this goes on for twenty years, or even longer, and the patient at last dies of some other malady. If organic disease of one organ of the body progresses so very gradually that ample time is allowed for alteration in the activity of other functions to take place, the duration of life may not be affected; and if the patient lives under really favorable circumstances, he may long outlive persons who were in good health some years after he became the subject of fatal organic disease. It must, however, always be borne in mind, that such persons are more likely to suffer from exhausting influences, cold, fatigue, etc., than others in whom the kidneys are healthy, and, therefore, they should always place themselves under medical supervision.

On the Nature of Structural Renal Changes.—Before we can decide upon the nature of many norbid processes, we must ascertain what was the exact change which constituted the first departure from the normal state, for this was the true starting point of the derangement or disease, and we must make out which of the many textures present in the organ was the particular one first affected. Of late years far too great an importance has, in my opinion, been given to the interstitial tissue-many pathologists having apparently satisfied themselves that it is in this interstitial connective tissue that many morbid changes really begin. Thought has for some time been running along the lines long ago laid down in favor of the paramount importance of what was called intercellular substance supposed to be deposited from the blood, and subsequently by the suggestion of the very

important part supposed to be played in the process of inflammation by the so-called connective-tissue corpuscles.

In the acute and chronic changes in the kidney an importance has been given to the insterstitial tissue, which I for one cannot allow that it deserves. The conclusions rest, in part, upon theoretical grounds, and in part upon observations made upon specimens of organs in very advanced disease, which have been for the most part mounted in Canada balsam, a method which is quite unfitted for researches having for their object the determination of the real nature of the changes which occur in tissue elements in disease.

The nucleated fibrous tissue which is supposed to support every uriniferous tube and every Malpighian body is one of those many inventions which has retarded, and seems likely to continue to retard, physiological and pathological progress. This fancied supporting framework of intertubular fibrous or connective tissue has led to the superposition of hypothesis upon hypothesis, until a purely artificial pathology, based upon tissues and processes which do not exist in nature, has been built up. The tissue itself is differently described. According to some authorities it is a firm framework of fibrous tissue, while by others it is spoken of as clear and transparent, translucent, structureless. It is said to be of definite structure, and to be composed of indefinite connective tissue. It is, however, certain that at an early period of development, when the tissues are soft and more in need of support than at any other time, it is absent. In inflammation the so-called nuclei of this supporting framework of connective tissue are said to be intimately concerned. The fibrous tissue is increased, according to some, in consequence of hypertrophic changes, while by others it is supposed that the lymph exuded from the blood is the source whence the fibrous tissue is eventually derived. In any case there is an increase of the fibrous tissue which, as time goes on, condenses and contracts, and constricts the uriniferous tubes and vessels so that they are caused to waste and to undergo other pathological changes, such as fatty degeneration and granular or fibrous alteration. The consideration of these changes has led to the

division of renal diseases into two classes, according as the secreting tubes or the intertubular connective tissue is the seat of pathological change.

Although such an arrangement may be supported by appeal to the pathological alterations in structure observed in some forms of renal disease, it is too arbitrary and artificial to be accepted as satisfactory or final. The cases which are regarded as exclusively due to intertubular changes often exhibit evidence of tubal alteration, while the tubes themselves are seldom exclusively affected. In both classes the starting point of renal change is the cells, and the degree of disturbance occurring in them may determine whether there shall be slight or considerable intertubular alteration. It seems to me that any classification founded upon such principles is open to the objections which attach to the old division of inflammation into purulent and plastic, or suppurative and adhesive, or the modern catarrhal and croupous. The differences do not depend upon differences as regards the inflammatory process itself, but are determined rather by the particular tissue affected, and the extent to which the inflammatory process is carried, or to its intensity.

In endeavoring to determine the nature of the initiatory changes in renal disease, I think the interstitial matter may be entirely left out of consideration. The changes begin in the cells of the uriniferous tube or in the blood. It is doubtful whether the interstitial matter which does exist in the adult, and which increases as age advances, takes any active part in the changes which occur, for the pathological actions may run their course at an early period of life, before any such tissue is formed, and in animals where it cannot be demonstrated.

I attach immense importance to blood composition and blood change in inflammatory diseases of various organs, and believe this to be the true origin of most acute inflammatory diseases. In all fevers and most acute inflammations blood change precedes the characteristic phenomena. Blood change is the starting point, and may be looked upon as the cause of what follows. The other factor must be some unusual "tendency" or susceptibility," or inherent weakness or developmetal defect of the

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particular organ which is the subject of attack. It is in this way I should venture to answer the difficult question which presents itself for solution in so many cases. Why, for example, is the lung the organ involved in one case, the kidney in another, the stomach, the intestines, the liver, in others? In contagious fevers the poison gets into the blood and works changes therein; nay, in the case of many the poison germ itself will be inoperative unless some prior changes in the individual's blood shall have prepared the circulating fluid for its reception and nutrition. I feel convinced that if only the blood could be kept right, thousands of serious cases of illness would not occur, while I am of opinion that the persistence of a healthy state of the blood is the explanation of the fact that many get through a long life without a single attack of illness of the class under consideration, although they may have several weak organs.

If the renal epithelium be unequal to the work assigned to it in cases of physiological pressure, the circulation of the surcharged blood in the vessels is slowed, distention of the capillaries occurs, thinning of their walls, and escape of liquor sanguinis with multitudes of bioplasts. These last grow and multiply in their new situation outside the capillary walls, and are the agents concerned in the development of the fibroid material which gradually accumulates. Now could the renal epithelium have adequately discharged the extra work put upon it the blood would have been depurated at the proper rate, free diuresis would have occurred and all would have gone well; or if at the right moment free purgation or active diaphoresis had been adopted the same effect would have been produced. An altered state of blood, a departure from the normal physiological condition, and a disturbed state of action of the bioplasm of an organ due to inherent weakness, often hereditary, sometimes of developmental origin, will enable us to adequately explain the first step in many forms of acute and chronic disease. In acute renal inflammation the blood change seems to be the first alteration, the epithelial failure next in order, and the exudation or effusion of matters interstitially the third. This last may occur or not, according to the intensity of the disturbance. In an