Walter Rudolf Hess won the Nobel Prize for Physiology or Medicine in 1949, for his work in analyzing the function of the diencephalon, part of the interbrain, and its role in coordinating the body's internal organs. Introduced to the natural world by his father while still a very young child, Hess later wrote in an autobiographical sketch in A Dozen Doctors: "As time went on, I became aware of the significance of the ecological setting... of the specific interrelationship between flora and fauna.... More and more it became clear that functional manifestations, such as the germination of a seed or the rapid sprouting of a shoot from a willow, were more apt to capture my mind than purely morphological features." This emphasis on function and relationships carried over into much of Hess's work, particularly his investigations into the biological basis of emotions and the workings of the circulatory and...