On account of the conflicting arguments placing a renal neoplasm under the classification of hypernephroma, considered here as arising from a suprarenal rest or a carcinoma, which we will consider as arising from kidney tubercular epithelium, I have attempted to find in the structure of the growth, gross and microscopic, sufficient similarity to its parent organ to suggest its origin. Sometime ago, I studied all the kidney tumors in the surgical pathology museum prior to 1921, some twenty-three in number, and placed four which had been diagnosed carcinoma with the hypernephromas. Of these twenty-three cases, I have been able to follow only twelve in all particulars. In the study of these twelve specimens, I have classified five as hypernephroma and seven as carcinoma. This classification was based wholly on their structure. To my great interest, it was later found that the patients whose disease was diagnosed as hypernephroma were still