lead to varying degreesof chemical fractionation, while Urey discussesa Moon which underwent major differentiation about 4.5 b.y. ago. He accumulates the Moon at low temperatures and permits it to be heated from the outside to generate the extensive crystalline rocks returned by the Apollo missions. Levin also reviews the evolution of the Moon in view of the new Apollo data. On this basis, he m-examines models of thermal evolution of the Moon and concludes that we must continue to evaluate initial temperature models. The final paper in the book by Middlehurst discusses the tidal correlation of lunar transient events and moonquakes and suggests that both are related to the lunar rille system. In conclusion,this book is an essentialpart of the library of any student of the Moon. Many of the papers are excellent summaries of specificfields. It can be faulted on only three counts. (1) The coverage of lunar science is uneven. (2) Some of the papers are of dubious importance. (3) The book representsour understandingof a subject which is changing so rapidly that it is difficult to write, let alone publish material. Nevertheless, I have found the book to be a useful reference volume representing a diversity of views, and I encourage lunar scientists to study parts of it in detail. Departmtmt of Geology, uraiueT~ityof Toror&ti?, Tasty, Ontario, Cariuda
Proceedings of the Fourth Conference on Origins of Life-Chemistry and Radioastronomy edited by LYNN MARUULIS. Springer-Verlag, New York (1973) 291 pp, $17.20 TIUS BOOK contains the edited transcript of the dialogue of a group of twenty-five participants at the fourth and last of a series of conferenceson the Origins of Life. As with the published records of the other conferences, there remains a question regarding the scientific value of publishing these or any informal dialogues. This particular dialogue is well-organized into eight major sections, and conversationsin the differenttopic areas are easily accessible. Usefulness of the book is limited, however. Although a reference list is provided which serves as a guide to the literature, the book itself should never be cited, because of its generally undocumented content. Nevertheless, the book may yield ideas for future research in that gaps in knowledge become all too evident in some of the conversations. Also, the book may provide some entertainment for the reader who knows something about the personalities involved. At least two very important messages can be distilled from the conversations: (1) a call for more rigorous ident~cations of the organic compounds found in studies concerned with the origin of life; (2) a realization of the equivocal nature of some of the organic geochemistry that has been applied to studies of the early Earth. The section of the book dealing with radioastronomy seems particularly instructive. The editor’s preface provides an utmsually comprehensive summary of what this book is all about. She reaches one very sobering conclusion: “Yet, it must be admitted after this five-year attack from various angles, prejudices and disciplines, the central problem inspiring these conferences,perhaps slightly better defined, is as unsolved as ever.” This book, like the minutes of a meeting, will probably be of historical interest only to a limited number of people besides perhaps those who participated in the conference. KEITH A. KVENVOLDEI-T Evohtim Bras&, Planetary l3iology Ditiioro, NASA-Am Research Center, Moffett Field, Ca 94036, U.S.A.