The causes of catarrh of the bladder are never single. It always takes two causes to produce true catarrh of the bladder--one mechanical, and one chemical. After a traumatism inflicted on a healthy bladder, with proper care the patient recovers entirely. If, however, he insists upon keeping up and about, continues to drink liquor, and does not avoid straining at urination, the membrane about the neck of the bladder, irritated by the ammonia from the decomposing urine, secretes an excess of viscid mucus, the pus becomes gelatinized by the ammonia, the constant straining leads to hypertrophy of the muscular coat, the nerves lose their acute sensitiveness, and the milder persistent malady, chronic catarrh, is set up, to continue perhaps for an indefinite period. Infiltrations of the bladder-walls with tubercle or cancer, urinary calculus, and, notably, enlarged prostate, stricture of the urethra, tumors of the bladder, hernia of the bladder, exstrophy, over-distension of the bladder from stricture, spasm of the urethra, coma, paralysis, or other cause, may be the traumatic element, while the liberated ammonia from the alkaline decomposing urine furnishes the chemical element; and the two causes, if continued, occasion and maintain the condition known as chronic catarrh of the bladder. In coma or the delirium of typhoid fever or paraplegia or hemiplegia (sometimes) the bladder becomes over-distended and atonied, perhaps paralyzed. Here the use of the catheter appropriately, with great gentleness, may relieve the patient without even the intervention of acute cystitis; while, on the other hand, acute cystitis may come on and be cured, or, if ammoniacal urine be allowed to accumulate and the bladder be not washed out so long as it is unable to entirely expel its contents, chronic cystitis, catarrh, results. I have known several cases of partial paraplegia and other disorders in which the patient could void no drop of urine except through a catheter, where there never had been any chronic catarrh, no stringy mucus, hardly a pus-corpuscle, through long years of the disability, owing to intelligence in the attention to emptying and washing out the bladder instituted by the physician having first charge of the case.