THE following cases are of interest not only because of the presence of multiple large renal calculi, but for the fact that in each case the calculi formed after a previous operation for their removal. Case 1. R. C, 32, laborer, native of the Azores, coming to this country two years ago. Does not speak English. F. H. Unimportant. P. H. Large calculus removed from the bladder eight years ago. P. I. For the past year has had pain in left kidney region and along the course of the ureter, and pus in the urine. P. E. Tenderness over both kidney regions. Otherwise negative. Cystoscopic examination made by Dr. E. J. O'Brien who reports: “Urethra presents tight posterior stricture, but 22F cystoscope was passed with difficulty. Bladder showed stone size of a small hen's egg. Mucosa red and injected, and bladder itself contained pus and blood. Ureteral orifices normal in appearance. Both ureters catheterized. Both urines contained pus and blood. Phenolsulphophthalein tests: App. time, left side, 27 min. App. time,...