Current Topics in Radiation Research. Vol. IV. Edited by Michael Ebert and Alma Howard. Cloth, $19.00. Pp. 430, with figures. Amsterdam, The Netherlands, North-Holland Pub. Co.; New York, John Wiley & Sons, 1968. Once again, Ebert and Howard—with an able assist from their publisher—have turned out a timely, broad-ranging volume of current topics in radiation research. As the field of radiation research itself is constituted, so too is Volume IV, with its topics ranging from fundamental chemical reactions in vitro to tumor and normal tissue responses in vivo and in man. The book starts with two chapters dealing with radiochemical questions. A. 0. Allen writes on hydrocarbons and W. M. Garrison on organo-nitro-gen compounds. Included, in both instances, are matters of purely theoretical interest as well as ideas and findings which hopefully will in time support a bridge between elementary absorption processes and biological effects. K. F. Swingle and L. J. Cole, writing together, and D. Petrovic contribute chapters dealing with nucleic acids. Swingle and Cole are concerned with early effects, mainly in nondividing cells—e.g., lymphoid and liver cells—and chiefly the effects on DNA since these authors feel that by a process of elimination DNA remains the most probable site of primary irradiation reaction. Petrovic reviews the body of literature dealing with restorative effects attributed to the addition of DNA, or DNA precursor material, to irradiated cell and animal systems. While the results in this area remain somewhat controversial, Petrovic's review is timely and of value, in view of the importance of the biological implications of postirradiation “DNA therapy.” A third instance of complementation in this volume is evident in the chapter by B. A. Bridges and R. J. Munson, writing about damage and repair in E. coli, and in the chapter by G. W. Barendsen who takes up related questions in mammalian cells. While topically these chapters do not interrelate completely, a worthwhile integration can be made by the reader interested in general questions in cell biology. Finally, to complete the range of subject matter, F. Ellis writes about theory and practice in the radiotherapy of tumors. Many readers, here too, will make meaningful integrations between data of the type introduced by Barendsen and the analysis of a critical medical problem as undertaken by Ellis. Volume IV, as with those preceding it, has much to offer. Student and researcher, theorist and pragmatist—all will find here a worthwhile addition to a worthwhile series.