The French physiologist Charles Richet once remarked: "The living being is stable. It must be in order not to be destroyed, dissolved or disintegrated by the colossal forces, often adverse, which surround it. By an apparent contradiction it maintains its stability only if it is excitable and capable of modifying itself according to external stimuli and adjusting its response to the stimulation. In a sense it is stable because it is modifiable—the slight instability is the necessary condition for the true stability of the organism." It is well to bear such paradoxical generalizations in mind whenever supposed menaces are pointed out as a possible marked change in the environment or dietary regimen. No one will gainsay that serious upsets may attend pathologic conditions, particularly when the regulatory functions are seriously impaired; but the normal tendency is invariably toward the preservation of "steady states" in the body.
Cannon1 has pointed