The increase in the urea might, of course, in the renal dropsies, be ascribed entirely to the excretion of that portion of the urea which, as Christison pointed out, is contained in the anasarcous fluid. But when this increase is found to occur in all dropsies, cardiac and splenic, as well as renal, the excess of urea may reasonably be referred, not only to excretion of urea which has been retained, but also to metamorphosis of the albuminates of the dropsical fluids. The large amount of chloride of sodium is doubtless attributable to the reabsorption of the fluid, which always contains a considerable proportion of chloride of sodium.

Diuresis, independent of thirst or lessened elimination from the skin or lungs, occurs in many diseases without dropsy. Thus, in almost all inflammatory and febrile diseases, in which there is no very great sweating or diarrhoea, the amount of urine is abnormally great during convalescence. It is possible that the water is retained in these cases, probably in the organs, especially the spleen, liver, and lungs. The amount of diuresis is not generally very considerable or long continued; the solids are in variable proportion, according as there has or has not been free excretion during the former period.

In certain cases of diuresis, two or more of these varieties are sometimes combined; there is at once greater thirst, lessened cutaneous excretion, and, in all probability, elimination of retained water. Beneke has minutely investigated a most interesting case of this kind. A man who had had ague, whose spleen was much enlarged, and whose urine contained a little albumen, but who had no dropsy, passed for a long time a large quantity of urine; the mean of twenty-four days was as follows:

The mean results in this case were then an increase of all the excretions, with a marked excess of urea. But during the course of the disease the variations were great; the excretions of the skin and lungs were clearly antagonistic to the urine. At the commencement of the case when the urine was least (1790 grammes), the insensible perspiration was greatest (3020 grammes); then gradually the urine angmented, and reached 4104 grammes, while the insensible perspiration fell to the remarkable minimum of 407 grammes, or much less than half its normal amount. The influence of lessened transpiration was therefore certain, and that of the fluid drunk is of course evident. That this was also previous retention of urea and chloride of sodium, is evident from the large quantity of each which was poured out.

In no variety of diabetes insipidus is any unusual extractive or saccharine matter, or dextrin, found. The statements of Thenard and Bouchardat, that "tasteless sugar" is present, have not been confirmed; and Bouchardat, indeed, has given up his original opinion on this point. Albumen is occasionally found, but is not common; and its presence is, so to speak, accidental.

SECTION V.

URINE CHARACTERISED BY GREAT EXCESS OF UREA

(THE WATER AND OTHER URINARY INGREDIENTS NOT BEING INCREASED).

Dr. Prout 2 supposed that there was a disease characterised by the formation of a large quantity of urea, although the water

1 Mean of seven days. Often there was no uric acid in the urine; on other days there were traces.

2 For Prout's last opinions, see the 5th edition of his great work, 1848, p. 94, et seq.

and the other constituents of the urine were unaltered in quantity. Subsequently, Willis particularly described this affection under the name of azoturia.1

The description given by Prout proves that he was not speaking of a mere relative excess of urea, in consequence of deficient water. Of the occurrence of this condition he was quite aware, and distinguished it carefully from the absolute ureal excess which he appears to have demonstrated by special analyses. Unfortunately, Dr. Prout was not in the habit of communicating his observations in detail, and the opinion rests, therefore, merely on the authority which is to be attached to his dictum. Those, however, who, in studying this subject, have been led to appreciate Dr. Prout's great care and accuracy, will not underrate the authority of any opinion of his, and will be inclined to believe that, if Dr. Prout asserted the occurrence of a special disease characterised by an excessive excretion of urea, such a disease must really exist.

The testimony of Dr. Willis, also, is very material on this point.

Dr. Prout states that the affection is rare, and, in specifying the causes, he enumerates dyspepsia from inattention to diet, intemperance, mental anxiety, sexual excesses, and mercurial irritation. He also states that the causes seem to him nearly allied to those producing diabetes mellitus; and infers that the azoturia may pass into saccharine diabetes, though he says expressly (p. 100) that he has never seen this occurrence.

I have never seen a disease of this kind. All the cases of excessive urea I have seen have been either connected with pyrexia or with peculiarity of diet (excess of nitrogenous substances), or have been examples of diabetes insipidus with excess of urea, and therefore not belonging to Prout's category of excess of urea without excess of water.

A case, however, has been examined by my friend, Mr. Sydney Ringer, which appears to be an instance of this disease.

It was in a middle-aged man, weighing 109 lbs., and being only 5 feet 3 inches in height. He was not febrile, and appeared only feeble.

This man, when on good hospital diet (which is not, after all, very abundant), and tranquil in the wards, passed in each twentyfour hours (mean of twelve days)—

or no less than 1130 grains of urea in cach twenty-four hours,

1 On Urinary Diseases, 1838.

or 10.36 grains to each pound avoirdupois of body-weight! The hourly amount of urea was greater in the day than night. There was a trace of sugar, but not enough to determine quantitatively. It seems difficult to call this case diabetes mellitus. İs Prout's conjecture correct, and is this case about to merge into saccharine diabetes? Is the urine large enough in quantity to bring it under the heading of "Diabetes Insipidus," or are we to look upon it as a typical example of azoturia?

SECTION VI.

URINE CHARACTERISED BY EXCESS OF URIC, OF HIPPURIC, OR OF PHOSPHORIC ACID.

An increase of uric acid occurs in pyrexia, in leucocythemia, in certain chronic liver diseases, and after an attack of gout, &c. But, apart from these cases, is there any disease distinctively marked by a permanent excess in the amount of uric acid? I believe not. The cases of supposed excessive production of uric acid are instances of elimination after retention in the kidney tubes or pelvis, or even sometimes in the bladder.

The cases of presumed excess of hippuric acid were observed at a time when the great amount of this acid in normal urine was not known, and when the ease with which hippuric acid is produced from benzoyl compounds was not understood. It is extremely doubtful whether there is a disease characterised by excessive formation of this acid. The doctrine of a "phosphatic diathesis" is now known to be erroneous. The phosphates precipitate simply from deficiency of acid, or excess of alkali, and their appearance is especially connected with lessened digestive power and impaired nutrition, or with urinary conditions, such as slight cystitis, leading to ureal decomposition. On this point, however, enough has already been said. The so-called "oxalic-acid diathesis" has been discussed in a previous page.

CHAPTER V.

RENAL DISEASES.

SECTION I.

ACUTE DISEASES.

Acute Bright's Disease.1

IN the early stages and at the height of the disease, the urine in this disease presents intensely febrile characters; it is small in quantity, deeply pigmented, and deposits urates. It contains a variable but usually a large amount of albumen and blood; there are sediments of desquamated kidney-, ureter- and bladder-structures, and voided renal cylinders; sometimes it contains large masses of coagulated fibrine, or partly decolorized clots.

Normal constituents.

1. The water during the early severe febrile stage is extremely scanty.

2. The urea is sometimes very much augmented, as in other fever cases (Mosler, Beneke), while in other instances it is below the normal amount.2 This occurs in cases with a large amount of albumen, and in which a great number of the renal tubes

1 This term is used in the sense in which it is employed by Rayer and Frerichs, to denote an intense febrile disease, which may come on after scarlatina and other exanthemata, or independent of these, and which is marked by signs of intense congestion of the kidney, with exudation and hæmorrhage into the tubes, and desquamation of the epithelium; the secondary phenomena are uræmic symptoms, to a greater or less degree, and, in the majority of cases, general dropsy. Acute desquamative nephritis is the term used by Johnson; inflammatory dropsy, by many

writers.

2 Frerichs gives 9.99 grammes of urea, as the mean of two experiments; Becquerel 9:49 grammes (Frerichs); and Gorup-Besanez 21.74 grammes. The deficiency of the urea has been noticed by many writers, especially by Christison, Scherer, and Renges (Valleix, Guide du Med. prat., t. iii, p. 423).