Claude Bernard - Homeostasis

The tendency toward internal stabilization of the animal body was first recognized by Claude Bernard. He was a great French physiologist of the nineteenth century. Through his studies of blood glucose and liver glycogen, he first discovered internal secretions. From a lifetime of study and experimentation he propounded the principle of constancy of the internal environment. 

Walter B. Cannon coined the name homeostasis.He was an American physiologist at Harvard University. He reshaped and restated Bernard's idea. From his studies of the nervous system and reactions to stress, he described the ceaseless balancing and rebalancing of physiological processes that maintain stability and restore the normal state when it has been disturbed.