 In many cases, mechanists did not explicitly respond to vitalists but simply moved forward with their research. Bernard (1865), was an exception. He addressed Bichat’s challenges by introducing a distinction between an organism’s internal and external environment. Mechanistic operations within organisms are carried out in the internal environment and jointly serve to maintain that environment in a constant state. Because mechanistic operations respond to conditions in the internal environment, they appear indeterminate when considered only in relation to external stimuli. Moreover, because these mechanisms work to maintain a constant internal environment, one could explain the ability of organisms to resist physical processes that might otherwise destroy them (for discussions of Bernard see Holmes 1974 and LaFollette &amp; Shanks 1994). Bernard’s approach was the foundation for Cannon’s later well-known work on homeostasis (1929).