pearance of large drops of fat. They are sharply defined, and show in a favorable light fine radiating stripes and also delicate concentric lines.

Tyrosine forms very fine short needles, made up into sheaves or bundles crossing each other at various angles. (Pl. IV., A.)

Sometimes leucine spheres are distributed throughout this formation. The addition of a drop of ether will prevent confusion of the leucine with fat-globules, for fat is dissolved by the ether. The crystals are soluble in caustic alkalies, but not in cold mineral acids.

Tyrosine crystals can be identified in two ways, by Piria's and Hofmann's tests. The first method consists in placing a small amount of the sediment in a watchglass, and moistening with a few drops of concentrated sulphuric acid; after an interval of twenty to thirty minutes add some water and neutralize the solution with calcium carbonate as long as it effervesces, and then filter. If, on the addition of ferric chloride which is free from acid, a violet color is produced, tyrosine is present.

The second method is still simpler. The sediment is diluted with water and boiled; to the boiling fluid add a few drops of mercuric-nitrate solution. If a red precipitate falls and the supernatant fluid is rose- or purple-red, tyrosine is present. Leucine and tyrosine occur in the urine very infrequently, seldom otherwise than with acute yellow atrophy of the liver and phosphoruspoisoning.

7. Fat.

The fat-globules which float on the surface of many

urines must not be regarded as coming from the urinary organs. We often find that the patient has been catheterized, and the fat has come from the oil used to lubricate the catheter. We must also be careful regarding the finely divided fat-globules under the microscope; they are apt to be from unclean object glasses, or from the urine having been collected in greasy bottles which have previously contained hair oil or some fatty emulsion, medicines, etc., or to be caused by milk having been emptied into the vessels used for the urine.

The assertions that entire fat-globules appear in the urine with excessive fatty degeneration of the kidney, we are unable to confirm by our personal observation. It seems very improbable, since the parts of the kidney affected by fatty degeneration do not secrete urine, so as to allow the fat-globules to enter. This view is strengthened by a careful dissection of the parts. An emulsion of fat is observed in the chylous urine of the tropics (galacturia), partly causing its turbidity. The turbidity from these causes is cleared up by shaking with ether. In such urine the sediment is peculiar; as the specific gravity of the urine is higher, the sediment will rise to the surface as a cream. The fat shows under the microscope various large spheres with sharp contours. Ether dissolves it. Cholesterine occurs sometimes along with the fat, but very rarely, and for the most part in a crystalline form, recognized by the clear, large rhombic plates. In Europe galacturia occurs very seldom.

[In England there have been several cases of chyluria reported,* some of which occurred in persons who had never been out of the country; and in some of them the urine at times seemed rather lymphous than chylous (i. e., the fat is absent, but albumen and fibrine remain the milky appearance being absent, but the capability of forming a clot spontaneously also remaining [fibrinuria]). The pathology of these cases is obscure. In chyluria, as observed in the tropics, where it is endemic, the symptoms may be of a very slight nature, with an intermittent character to the disease, and the patient's general health may suffer very little, or, there may be severe symptoms, such as renal colic or strangury, and the long-continued drain on the system may produce exhaustion and pave the way for grave intercurrent disease. In the urine of persons contracting the disease in the tropics, the filaria sanguinis hominis is so often found as to suggest a causal relation between it and the affection.]

8. Earthy Phosphates.

a. Amorphous. In ammoniacal urine we find regularly a heavy precipitate of grayish-white sediment, which the beginner often mistakes for pus. This sediment is the precipitated earthy phosphates, i. e., calcium and magnesium phosphates. As we have said, these salts are only soluble in acid fluids, and consequently must have been precipitated from the time when the [Roberts (op. cit., p. 335 et seq.).]

urea changed to carbonate of ammonium, thereby rendering the urine alkaline. Under the microscope the earthy phosphates appear as granules of various sizes, which do not form the mossy groupings that characterize the urates. Their identification chemically is very easy. The urates, with the exception of urate of ammonium, occur in acid urines, while the earthy phosphates (the crystalline calcium phosphate which occurs in acid urine being excepted) are found only in alkaline urine. The reaction with litmus settles the question as to whether we have to do with urates or phosphates. By heating, the urates disappear while the sediment of the phosphates increases. By addition of KOH or Na OH the urates dissolve, while the phosphates remain unchanged. The distinction between phosphates and pus is shown in Donné's test. (P. 171.)

All circumstances which lead to alkaline fermentation of the urine, or cause the alkalinity of the same, tend to the formation of the sediment described, which is precipitated in mass proportional to the amount of the earthy phosphates in solution.

Only exceptionally, with bladder catarrh or after the use of a great amount of alkalies, is the urine alkaline upon evacuation. In these cases it is already turbid from the precipitation of the earthy phosphates thrown down in the bladder. Generally the turbidity appears only a shorter or longer time after evacuation of the urine. These amorphous earthy phosphates are often mixed with a beautiful combination of magnesium phos phate with ammonium-the so-called triple phosphate.

b. Crystallized calcium phosphate.-Crystalline calcium phosphate, of the formula PO̟ HCa + 2H,O, is found in pale weakly acid urines, which have a tendency toward alkaline fermentation.

This sediment appears with some persons as an individual peculiarity oftener than from other causes. We have observed individuals living under healthy normal conditions to have in summer a daily sediment of crystalline calcium phosphate in the urine.

Under the microscope the crystals appear clubshaped, with broad oblique bases. They may be isolated, or may lie over one another, the points converging together, often forming a rosette, the periphery being formed by the bases of the crystals.

In some cases the crystals do not simply form circles, but make up segments of spheres. (Pl. III., B.) (Other forms are described in K. B. Hofmann's “Zoochemie.")

The forms of the crystals are so characteristic that confusion is hardly possible. The triple phosphates which may accompany them in later stages of alkaline fermentation have no points, and moreover form no bouquets or rosettes.

From uric acid this sediment may be distinguished by the fact that it is colorless and disappears on addition of acetic acid.

9. Magnesium Phosphate.

In neutral or weakly alkaline urines, which we observe after the internal use of the fixed alkali carbonates