Gregory J. Morgan, <i>Cancer Virus Hunters: A History of Tumor Virology</i> Baltimore: Johns Hopkins University Press, 2022. Pp. 392. ISBN 978-1-4214-4401-7. $50.00 (hardcover).

Morgan's book is an attempt to tell the history of tumour virus research by looking at the lives and work of those who shaped this field.Morgan argues that the study of cancer viruses has been much more important for the history of molecular biology in the twentieth century than is generally assumed, and has been neglected by historians.In essence, the book looks at the laboratory studies that can be viewed as leading to the discovery in the 1970s and 1980s of the oncogenes src and ras, and the tumour suppressor p53, starting with Peyton Rous's experiments in the early twentieth century that suggested that an 'agent' in cell-free filtrate was responsible for the transmission of tumours between chickens.We may or may not agree with the premise that 'the full story of molecular biology's incredible jumps in understanding remains a mystery' or 'represents an unknown unknown' (p. 1).In fact, historians of twentieth-century life science can draw on a good deal of excellent and relevant literature on the history of molecular biology and even cancer virus research, and Morgan knows and cites this literature.However, that does not mean that there is no need for this book.Most historians of recent science draw a distinction between insider or participant histories of science on the one hand, usually published in the same journals as research in the respective field, and histories written by professional historians on the other.Insider histories are often better at paying attention to technical minutiae -that is why professional historians like to use them.However, these insider histories can be frustrating when they display ignorance of existing historiography and historical workmanship and a sometimes very naive belief in the inevitability of progress in science.Morgan combines an interest in and an eye for technical details as we usually find them in participant histories with awareness of the historiography of recent life sciences, while drawing on a wide range of unpublished primary sources, especially interviews and archival materials.The book focuses on what happens in the lab and largely relegates observations about social and political contexts to the footnotes (except where they can be seen to interfere with the science, for example in Germany under National Socialism, fascist Italy, or communist Czechoslovakia).The book is structured chronologically and topically.It starts with a chapter on Rous and other early twentieth-century researchers working with viruses causing tumours in chickens, rabbits and mice, followed by a chapter on what came to be known as the polyoma virus.Along the way, we are looking at virus research taking shape as a field of study, and the emergence and use of approaches that would turn into standard tools, such as cell