This book gives a review of the life (16th Febr. 1848-21st May 1935) and work of Hugo de Vries, both aspects being treated separately. Its biographical part, however, does not conform to the necessary requirements for writing a modern biography. In the first place, the chapter dealing with the life of Hugo de Vries (only 24 pages in length) is far too short to ensure an adequate description of his youth, student years, teaching activities, professorship, travels, social life, colleagues, etc. In the second place, no attempt has been made to present a reconstruction of a human being, living under certain social conditions and provided with an individual character; instead, we get an impression that Hugo de Vries’ character was composed of the most perfect qualities of his ancestors, and that human foibles were no part of it. But only gods are infallible; it is the weak sides that make it possible to identify a human being. Moreover, no attempt has been made to correlate the various phases in the life of de Vries with the various phases which can be distinguished in his scientific activities. In trying to ascertain the value of this book, we can sum up four aspects: the very beautiful illustrations, 74 in all, most of them full-page photographs, some of them never published before; the enumeration of his graduands (14), decorations (9), honorary doctorates (9), honorary memberships (23), and memberships of societies and academies (no mention of the Royal Botanical Society of the Netherlands), memorials, etc.; the chronologically arranged bibliography of publications by de Vries (450); and a rather good impression of de Vries’ many-sided activities in the fields of cell physiology, genetics, and the theory of evolution. This last aspect has been treated in the second part of this book, mainly with the aid of a selection of illuminative passages (in Dutch translation) from the publications of de Vries.