it is in granular and partly crystallized masses. When crystallized from pure solutions, it often appears as fine, dark-coloured needle form crystals.1

8. Sediments of Tyrosin.-Tyrosin, when appearing as a sediment, forms a greenish-yellow sediment, composed of heaps of fine needles. These can be obtained also by evaporation.2

9. Sediments of Cystin (CH.NO,S,).-Cystin, when present in the urine (see Chapter III), is either dissolved or in part precipitates. In the latter case it either forms a white or light fawncoloured, amorphous, rather bulky sediment, or appears at once in six-sided plates; in both cases ammonia dissolves it, and from this solution it crystallizes on spontaneous evaporation. It is insoluble in acetic acid, and does not disappear when the urine is gently warmed. Calculi are generally white or yellowish, or sometimes green or bluish (from pigment?).

10. Sediments of Xanthin.-Although xanthin is found in rare calculi, it has not yet been unequivocally detected in sediments. Douglas Maclagan found a sediment in the urine of an hysteric girl, composed of earthy phosphates, and a substance considered to be xanthin,3 but Scherer doubts whether the reactions were characteristic.

III. Third class of Sediments forming in the Urine after

exposure to the Atmosphere.

1. In acid urine, fungi occasionally soon appear; they have been noted by many observers, and have received a very full examination from Hassall.6 The fungus is the Penicilium glaucum; and its spores, thallus, and fructification can all be found in different specimens of urine.

Hassall has observed that the Penicilium requires for its appearance a certain amount of animal matter, probably epithelium and mucus; it grows very slowly in filtered urine;

1 To recognise it fully, it must be separated, and then, perhaps, the best plan is to sublime it carefully. Scherer has given an excellent test, which may be used for the impure or the sublimed leucin. The suspected leucin is placed on platinum, carefully moistened, and then dried with nitric acid. An almost imperceptible flake is left. This is moistened with caustic soda, and then evaporated carefully over the spirit-lamp. The leucin then forms an oily-looking drop, which does not adhere to the platinum, but can be rolled about.

2 Scherer's test for tyrosin is to treat it with nitric acid, like leucin, and then to use, as for leucin, a little liquor soda. The nitric acid gives a deep orange-yellow colour, which becomes deep yellow on evaporation. The soda gives the yellow flake a red tinge, and, on heat and evaporation, a black-brown residue is left. The distinction, therefore, between leucin and tyrosin is easy.

3 Monthly Journal, 1851, August, p. 121.

4 In his Report on Path. Chem., in Canstatt's Jahresb. for 1851, p. 49.

5 Heller, Basham, Bennett of Edinburgh, Spencer Thomson (Med. Times, 1849), MacDougall (ibid.), and some others, directed particular attention to this fact twelve to fifteen years ago.

Med.-Chir. Trans., vol. xxxvi, 1853, p. 23.

it wants but little air, and will appear in urine in a well-corked bottle. It is particularly influenced by temperature, and grows most rapidly in acid urines containing much mucus, and exposed to a temperature of 70 or 80°.

The sporules appear often in a few hours: the smallest are perfectly globular, fromd to th of an inch in diameter (Hassall); the larger sporules are vesicular, and contain an eccentric nucleus. In a few hours the smaller sporules elongate and become oval. The thallus is formed in two or three days, from both larger and smaller sporules. In addition to these sporules, large globular bodies are seen, from which also the filaments of the thallus take their rise. These large globules, however, are not merged in the thallus, as the smaller sporules are, but remain as terminal or lateral bulgings on the filaments (Hassall). After several days, a mould or aërial fructification appears on the surface.

The Penicilium glaucum may be found in an alkaline urine, because the previously acid urine may have become alkaline; but it does not grow, or but slightly so. The different condition in which it is found in different urines, is probably owing to variations in the acidity.

Hassall thinks the development of the Penicilium may take place even in the bladder. It occurs in albuminous and nonalbuminous urine. The spores sometimes are coated with lithates; less frequently with phosphates.

2. The Torula cerevisiae is found in saccharine urine, and has been supposed to be the best test of a small quantity of sugar. It begins to form in two or three hours. It appears first just below the surface of the fluid, and forms delicate gelatinouslooking little masses, which under the microscope are found to be made up of round sporules, about th of an inch in diameter. In two or three days the gelatinous masses are found to be more consistent and whiter, and then, becoming heavier, sink and form a fawn-coloured stratum, which is made up of spores much larger than those first formed (th to th of an inch, Hassall), and of a few beaded threads. A few days subsequently the aerial fructification appears.

1

28

Air in large quantity is necessary for the growth of the Torula; during its growth the sugar is destroyed, carbonic acid is evolved, and various acids are produced. (See "Diabetes Mellitus.")

3. Vibriones and Monads.-In specimens of urine containing much mucus, with or without albumen, vibriones rapidly form; they are even detected sometimes in a few minutes after the urine is passed, but usually appear in from two to twelve hours. The urine is feebly acid or alkaline.

30

The vibriones are linear, about 5th of an inch in length, and move rapidly through the urine.

CHAPTER

III.

ON THE COMPOSITION OF THE URINE IN DISEASE.

THE urine is examined in diseases for two purposes; 1st, to discover the condition of the urinary organs; 2d, to determine, as far as a single excretion will permit, the course of the abnormal metamorphoses of tissues in the body, which lead to alterations in the composition of the several excreta. determine this with complete exactness, we require to understand thoroughly the normal metamorphosis of tissue, and the changes produced in it by disease. We are still, however, almost entirely in the dark on this great topic, and the facts now known respecting the urine in disease can be regarded as merely the preliminary inquiries necessary to prepare the ground for subsequent more complete investigation. It is, of course, extremely desirable, in disease as in health, that the urine should not be alone examined, but should be regarded in connexion with the excretions of the skin, bowels, and lungs. Everything in the body takes place with the most rigorous chemical exactness, and changes in one excretion must be intimately and accurately connected with changes in the others.

I have therefore, as far as the plan of the work would permit, referred to all the excreta, reserving, however, full details of the intestinal, pulmonary, and cutaneous discharges for a subsequent work.

In disease many of the physiological conditions of age, weight, food, atmospheric conditions, &c., are as active in producing changes in the excretions as in health. In fact, all or many of the circumstances described in the first chapter of the First Book must be in action in every case of disease; and we may erroneously attribute to the disease what is actually owing to physiological conditions. And in disease we

have also the additional agencies of remedies and of the pathological processes; so that the problem becomes in the highest degree complicated and obstruse.

Moreover, owing to the difficulty of weighing sick persons, especially in acute diseases, and to the impossibility of knowing in many cases what is the amount of their physiological excretion, it is extremely difficult to estimate the exact degree of variation in the excretions.

Yet with all these difficulties and imperfections, the examination of this important subject has greatly advanced, especially since the introduction of the volumetric method of determining the urinary constituents; and we have every reason to hope that future observations will yearly improve in accuracy and in extent.1

In examining the urine, the first object is to determine the amount of the normal constituents, and the second is to detect the presence and quantity of abnormal substances.

In determining the amount of the normal constituents in sick persons, we must remember that we scarcely ever know beforehand what is the physiological amount proper to the individual, i. e. the amount he excreted daily in a state of health. And yet, without such knowledge, how are we to tell whether he is passing a greaterorless quantity of water, urea, uric or sulphuric acids, &c., than he did when in health. We cannot, of course, apply to the individual the average derived from the collective analyses in a number of persons, though this has been often done. For example, the mean excretion of urea in men between twenty and forty, is 33 grammes (512 grains); but we should greatly

1 Proper analyses of the urine in disease were, up to a recent date, almost impossible. The determination of the urea, for example, was difficult and faulty, and demanded so long a time as to render a daily analysis impossible. Unfortunately, too, the plan was adopted of determining merely the per-centage amounts of the constituents a method which gives very little useful information. The great work of Simon, which has been so ably translated by Day, loses some of its value from this cause; and this is the case with almost every work on the subject, except the treatises of Lecanu and Becquerel, who, a quarter of a century since, maintained the necessity of determining the absolute amount excreted in a given time. In this country, I believe, Dr. Routh was really the first who clearly perceived this point, about twenty years ago, and his observations would have been most valuable had it been possible at that time to make more frequent and continued analyses. But even after this improved method was used, the great variations occurring from day to day were not sufficiently considered, and conclusions were often attempted to be drawn from the analysis of the urine of perhaps only a single day. Moreover, and even up to the present time, the desirability of referring the amount of excretion to a definite amount of body-weight has not been always seen, and hence many observations are even now wanting in true scientific accuracy. Finally, the proper methods of calculating the results, and of fixing the true mean, were not sufficiently understood. So that good analytic processes, methodical application of these processes, and proper estimation of the numerical results given by them, were till lately all wanting. I have less hesitation in saying this, as I have myself passed through the whole series of errors here referred to.

err if, in investigating the urine of a particular patient, we concluded that, in health, he would pass 33 grammes of urea daily. A glance at the table (p. 7 of Introduction) shows that he might pass either an average of 18 grammes, or of 45 grammes daily, or any amount between these two figures. How then are we to form a conception of the patient's healthy excretion?

We must either continue our observations beyond the period of illness into that of complete convalescence and health (a plan always to be adopted, if possible), or we must form a provisional estimate of what amount the patient would pass in health.

The formula for this estimate I offer merely as an attempt at a solution, and can only hope that some more satisfactory plan will soon be made out.

The ratio of excretion to body-weight is, on the whole, the most constant fact at present known, and must form the basis of our calculation. The ratio is not, however, uniform. Thus, in the case of the urea, it has been shown that, in different persons, 1 kilogramme of weight may excrete either 0.420 or 0.529 grammes of urea, or any number between the two, the difference between these two persons being thus 0.109 grammes. Therefore, if each person weighed the same, let us say 65 kilogrammes, one would excrete 27.3 and the other 34-385 grammes of urea in twenty-four hours-a difference of more than 20 per cent. These numbers refer only to mean amounts drawn from several days, but on any one day the range may be from 0.25 to 0.66, or even more. The variations are probably not less with the other ingredients.

Yet, as already said, this method offers the greatest certainty of any. I would propose to use it as follows:-As weights in this country are usually taken in pounds avoirdupois and grains, I give them only here; but a simple calculation would bring out the results in kilogrammes and grammes, if necessary.

Empirical formula for calculating the urinary excretion in a sick person whose normal excretion is unknown.

1. Ascertain the weight of the person in pounds avoirdupois. 2. Multiply the following figures1 by the weight; the result is the excretion in grains in twenty-four hours:

1 These figures are obtained in the following way:

Column 1, from the figures in the Introduction, page 24.

Column 2, from the table in p. 41, except in the case of the PO, of women, which is taken at the same amount as in men.

Column 3, from the calculated amount of urea for children (p. 44), and by assuming that the other ingredients are excreted in the same ratio as the urea. Column 4, by assuming that the excretion is midway between columns 1 and 3.