Congenital polycystic kidneys have always been of unusual interest. Though the clinical features and pathology of this condition are amply covered in medical literature, relatively little attention has been given to the collateral venous circulation. The pathology of the congenital polycystic kidney is well known, and the theories of its etiology are summarized by Gruber1 in three main hypotheses: the supposition of an inflammatory origin (Virchow, Beckman, Hertz), the neoplastic conception (von Michalowicz, Chotinsky, Lejars, Köster, Nauweck and Hufschmidt) and the theory of a congenital defective development (Witte, von Mutach, Borst, Staemmler). The recent work of Kampmeier2 is noteworthy. In the study of kidneys in consecutive embryonic and fetal stages, he finds that dilatations and cysts occur frequently between the convoluted tubules and the collecting ducts, and concludes that a period occurs in fetal life that is normally characterized by the presence of numerous cystic renal tubules. If