This volume is concerned with the clinical aspects of urology in childhood; the anatomy, physiology and pathology are discussed only where they have a direct bearing upon the clinical problem, and for a detailed description of these aspects, and of operative technique, the reader is referred to other volumes of this series. Emphasis is laid upon the disorders peculiar to infants and children, so that diseases such as tuberculosis, the manifestations of which in the child differ little from those in the adult, receive less attention. Childhood is deemed to cease with the completion of puberty, though illustrations have sometimes been taken from adolescent cases. The personal views expressed in this work are based upon experience at The Hospital for Sick Children, Great Ormond Street, at St. Peter's and St. Paul's Hospitals, and at the Institute of Urology, University of London. I am deeply indebted to all my colleagues and assistants at these institutions for their help and co-operation both in the trea.tment of cases and in the preparation of this volume. I would particularly wish to thank Mr. T. T. TwrSTINGTON HIGGINS for introducing me to the urology of childhood, Drs. M. BODIAN, R. C. B. PUGH and L. L. R. WHITE for their assistance in matters of pathology, and for preparing specimens for illustration, Dr. ''\\V. W. PAYNE for his advice on biochemistry, Dr.