Later, the milky fluid separates into three layers. On the top there is formed a cream-like pellicle; at the bottom a scanty reddish sediment, sometimes including minute red clots; in the centre the mass of the urine forms a thick, "intermediate stratum, milky white or reddish white in colour, in which floats the contracted coagulum, If a little of the sediment be taken up with a pipette and examined with the microscope, it is found to contain red blood-corpuscles, lymphocytes, granular fatty matter, epithelium, and urinary salts, and mixed with these in a large proportion of cases, though not in all, microfilariæ. The middle layer contains much granular fatty matter; whilst the upper cream-like layer consists of the same fatty material in greater abundance, the granules tending to aggregate into larger oil globules. If a little of the coagulum be teased out, pressed between two slides, and examined with the microscope, microfilariæ, more or less active, may be found in the meshes of the fibrin. If ether or xylol be shaken up with the milky urine, the fat particles are dissolved out and the urine becomes clear; the fat may be recovered by decanting and evaporating the ether which floats on the urine. Boiling the urine throws down a considerable precipitate of albumin. When the urine contains only lymph, fatty elements are absent, or are present in but very small amount.
Recovery and relapse.— Chyluria comes and goes in a very capricious manner. Sometimes the urine remains steadily chylous for weeks and months, and then suddenly, without obvious cause, becomes limpid and natural-looking, and free from fat or albumin. Later a relapse will occur, again to disappear after an uncertain time; and so on during a long course of years.
Retention of urine. Retention of urine is nob an unusual occurrence; it is produced by the formation of coagulum in the bladder. The retention usually gives way after a few hours of distress, worm-like clots being passed.
Constitutional effects.— Although chyluria is not directly dangerous to life, yet, being prolonged, it
