Perforation of the ureter may occur, with consequent peritonitis. A permanent plugging of the ureter from failure of the calculus to pass will give rise to changes in the kidney to be subsequently described. In cases where only a single kidney exists, and this becomes obstructed, the symptoms of suppression of the urine may come on, including death by coma if the obstruction is not relieved. Ten days is the limit assigned by Ebstein beyond which recovery is not to be expected, but he mentions a case in which it took place after thirteen days of anuria. It must be remembered that a painful obstruction, or in fact any severe shock to one kidney, may produce a very great diminution in the amount of urine even when the other is sound. This is undoubtedly the result of nervous sympathy. One attack of renal colic renders another very probable, either immediately or after months or years. Several hundred small calculi may follow each other in rapid succession, or, on the other hand, a single one may leave the patient in peace for a long time. Much depends on the character of the calculus, the diathesis and habits of the patient, and upon the treatment. The subsequent history of the renal calculus belongs to surgery. After it has reached the bladder and failed to be discharged, it increases in size and is removed by lithotomy or lithotrity. The urethra, however, will usually permit to pass any stone which has come through the ureter. The patient who has just experienced relief from renal colic should be instructed to pass his water into a vessel which can be examined, and if the calculus do not soon make its appearance he should void the urine when stooping forward or even lying on his face, so as to bring the stone to the orifice of the urethra. It may catch in the urethra and demand surgical interference. The TREATMENT of the paroxysm consists chiefly in relieving the pain, which may be partly done by the hot bath or hot applications. Opium, or preferably morphine subcutaneously, is likely to be called for in large doses. Attention has been called to the danger of morphine in sufficient dose to relieve severe pain in cases where, as in renal colic, the pain is likely to be suddenly terminated by the natural progress of the affection, thus destroying the physiological antagonism which exists between pain and morphine, and allowing the drug to exercise its full power to an extent which may be over-narcotic. The use of atropine with the morphine will mitigate to some extent its danger, without interfering with its analgesic effects.