May 12, 1907–February 3, 2002

BY GEORGE N. SOMERO

CLIFFORD LADD PROSSER, AFFECTIONATELY known as “Ladd” by all who had the great fortune to interact with him during his seven-decade-long career, was a principal catalyst in the development of the broad field of comparative physiology. Born in Avon, New York, in 1907, Ladd either witnessed the early development or, indeed, fostered the very conception of many of the core research areas still being actively studied by biologists who describe themselves as comparative, integrative, or evolutionary physiologists. Workers in this broad area of biological investigation thus owe a major debt to Ladd Prosser, whose curiosity about nature led him to ask penetrating questions that continue to challenge and motivate us. Moreover, and very importantly, he helped to refine a philosophical context—the comparative method—that has enabled biologists to exploit the diversity of nature to elucidate the common, basic principles that characterize living systems.

This short biographical memoir of Ladd Prosser has two primary purposes. One is to provide a description of the scope and breadth of Ladd’s scientific accomplishments, which were foundational for so many areas of physiological study. The second is to describe the character of this remarkably insightful and humane individual in hopes of explaining his