=Epithelium in Urine.= The slight cloud seen in healthy urine contains epithelial cells. The source of these may be often determined under the microscope. The _bladder epithelium_ are the most numerous, the largest, and are squamous. Those from the _ureters_ and _renal pelvis_ are also squamous, but neither so large nor so numerous. The _epithelium from the uriniferous tubules_ are polyhedral with large nucleus or columnar. The cells from the _male urethra_ are also largely columnar. In cases, however, in which these cells are passed in large amount because of catarrh of the mucosa all alike tend to assume the globular form with large nucleus so that their true source cannot be certainly stated. It is only from such cells as have become detached without change of form that the seat of desquamation can be determined. If an excess of cells approximating to the kidney type are associated with albuminuria and cylindroid casts they become diagnostically significant. Polygonal cells darkly granular with large oval nucleus and nucleolus suggest kidney inflammation. If the granules are freely soluble in ether there is probably fatty degeneration. If hard, tough and glossy they suggest (but don’t prove) amyloid degeneration. =Pus Cells in Urine.= Pus cells, with multiple nuclei revealed by adding dilute acetic acid, may be found in small numbers in apparently healthy urine. When present in large numbers, they usually indicate a catarrhal affection of the mucosa, and especially pyelitis, cystitis, or urethritis. There is always cloudiness, excess of mucin, and, in the alkaline herbivorous urine, the liquid may be glairy or stringy. =Casts of the Uriniferous Tubes.= These usually indicate the existence of nephritis, yet they may be present in small numbers in the urine of healthy individuals under a slight toxic action such as alcohol. _Unorganized casts_ of urinary salts or hæmatoidin found in sucklings appear to have no pathological significance. _Organized_ casts, on the other hand, usually imply renal troubles, and especially inflammation. As these will be fully described under Bright’s disease, it need only be noted here that they may be composed in great part of _red globules_, _leucocytes_, _epithelium_, _bacteria_, _granules_, a _homogeneous wax-like matter_, _fat globules_, _hyaline matter_, or _urinary salts_. The predominance of one or other of these determines the nature of the cast. The observations of Mayer, Knoll, Bovida, Von Jaksch and others seem to show that the basis substance of urinary casts differs from all our familiar proteids and must be considered as a distinct nitrogenous compound, a derivative of one of the common proteids. GENERAL SYMPTOMS OF URINARY DISEASE.