_Case V_,—P. B., 27. Entered St. Vincent’s Hospital in February, 1911. Family history of no importance; was a heavy drinker; denied venereal disease. Pneumonia two years before admission. On his neck was a scar from a gland which suppurated at that time. Hematuria was his chief urinary symptom. Six years before he had had profuse, spontaneous and painless passage of blood in his urine, which stopped after a few days. When he was admitted to the hospital he had been bleeding again, but there were no other symptoms referable to his urinary tract. He had lost no weight. Immediately after entering the hospital he had delirium tremens, which lasted two weeks. At the end of this time, physical examination showed a very large low kidney on the right side and a slight pulmonary dulness at the base of his left lung. Cystoscopy revealed a normal bladder and normal ureteral orifices. The ureters were readily catheterized, the result of functional tests made being as follows: _Right kidney._—5 cc. of urine (in eight minutes) containing numerous casts, a few w. b. c., but no pus; 1.3% urea. _Left kidney._—3 cc. of urine (in eight minutes), containing no casts, no pus; 0.3% urea. One cc. of phenolsulphonephthalein was now injected intravenously. It appeared in eight minutes from the right side and in nine minutes from the left. During the next thirty minutes, the right kidney excreted 3% of the drug, while only a trace was obtained from the left side; in the following thirty minutes, the right side excreted 5.6% while the left showed only 1.7%. The above findings hardly seemed to jibe with the patient’s symptoms, and physical examination which suggested tumor of the right side. However, the amounts of urea and phenolsulphonephthalein excreted from the right side were so much greater than the amounts from the left side, that this fact certainly pointed to at least a greater involvement of some kind of the left kidney, irrespective of the condition of the right. Accordingly the left kidney was exposed and its upper third found to be a cheesy mass, obviously an old tubercular process. The patient was then turned over and an exploratory incision revealed a low-lying right kidney which was hypertrophied to twice its size, but otherwise apparently normal. The patient was now turned back and his left kidney removed. Both wounds healed by primary union, the patient making an uneventful recovery.