If the urine comes acid, but pus-laden, from the kidney, it will soon assume the contrary reaction in the bladder, and the pus will be changed by the ammonia into so-called muco-pus; the cells supposed to be characteristic of the pelvis of the kidney will, like the pus-cells, be so altered by the same causes, and so intermixed with similar cells from the bladder, that the distinction will be difficult or impossible. The presence of a few hyaline casts is very likely to be noticed, and indicates irritation, or perhaps a more decided implication, of the renal substance. Nothing, however, can be inferred from failure to find them. Hæmaturia is not so necessary an accompaniment of this form of pyelitis as of that arising from a mechanical irritant in the kidney. If, however, the urine does not become rapidly altered in the bladder, or if by any of the processes mentioned above the kidney urine can be obtained in a condition of comparative purity, the microscopic indications become more precise. A dull pain and tenderness in the loins and along the course of the ureters is a symptom of value, though by no mean conclusive, and should lead to a suspicion of pyelitis. A polyuria of short duration may be a purely nervous symptom, but a persistent flow of pale urine, which fails to settle clear, and of which the turbidity is caused by pus, is due in great probability to renal disease, and if it could be shown to come in this condition from the kidney would almost certainly denote pyelitis. The rational SYMPTOMS are of the greatest value as determining the extent and severity of the disease, although it may be impossible to distribute them with absolute exactness between the various organs involved--that is, bladder, pelvis, and renal substance. The occurrence of a single chill, or even of several, with rapid subsidence of the fever, is not conclusive, since the ordinary urinary fever supervening on surgical operations, even so slight as passing the catheter, is not necessarily connected with renal disease. A long-continued fever, not especially intense and of a more or less distinctly intermittent type, especially if becoming at some definite period decidedly more intense, is likely to mean the invasion of a new tract of mucous membrane, such as that of the renal pelves or even of the kidney-substance itself. Continued or remittent urinary fever is of very grave import. With this fever will appear the dry red tongue and the distressing anorexia, nausea, and vomiting, with either constipation or diarrhoea.