SHOCK AT THE MILLENNIUM II. WALTER B. CANNON AND LAWRENCE J. HENDERSON

Walter B. Cannon and Lawrence J. Henderson, students of shock in the early twentieth century, were contemporaries for four decades in the Harvard Department of Physiology. While their discoveries continue to have important clinical applications, both men established complementary methods of scientific investigation and description. Both men were inspired by Claude Bernard, hewing to his principle of the stability of the milieu intérieur. Cannon, the traditional experimentalist, employed a reductionist approach by holding constant the confounding variables of his experiments; in contrast, Henderson, the strategist of theoretical analysis, deduced patterns and relationships from less constrained models, focusing on complexity using mathematics and graphs. In delineation, Cannon described mechanisms; Henderson described the organization of systems. Cannon's emphasis on homeostasis with the identification of feedback arcs dominated shock research for the balance of the twentieth century. Henderson's perspective designating the importance of organization to those restorative mechanisms could well reemerge to dominate the twenty-first.