The 1890s was an exciting time in American biology, a time of great intellectual debate and turmoil. Much of this activity centered on the now-famous Evening Lectures delivered at the Woods Hole Marine Biological Laboratory on Cape Cod, where leading biologists gathered to research the leading issues of the day. There was no better way to learn about what was being discussed and debated at the cutting edge of biology than through the Evening Lectures. The lectures of outstanding scientists such as C. 0. Whitman, E. B. Wilson, E. G. Conklin, J. Loeb, and T. H. Morgan redefined our thinking about biology. These Evening Lectures stimulated major biological revolutions: the conversion of embryology to an independent discipline; the beginnings of ethology; the rise of genetics and especially cytogenetics; and the application of chemistry and physics to cell function-the birth of what is now called cell biology. Some of the central problems that scientists still puzzle over were first proposed at Woods Hole. Not only are these lectures important scientific accomplishments, they also provide an invaluable record of the beginnings of a truly American school of biology. Printed in a limited edition, they have remained inaccessible to many people interested in knowing more about the meteoric rise of American biology. Jane Maienschein has selected key lectures, written an introductory essay, and provided brief explanations of the significance and impact of each lecture. Ernst Mayr, distinguished biologist and historian, has added a Foreword about the intellectual importance of the lectures to the formation of American biology; and Paul Gross, present Director of the Marine Biological Laboratory, has contributed an Epilogue that conveys the excitement and later significance of the 1890s.