How did Claude Bernard connect vasomotor nerves to the regulation of body temperature?

Claude Bernard discovered that the vasomotor nerves play a critical role in regulating body temperature by controlling the dilation and constriction of blood vessels in response to environmental temperature changes.1

He demonstrated that this mechanism allows the body to maintain a stable internal environment, a concept he termed the internal environment, which is fundamental to homeostasis. Specifically, Bernard observed that in cold weather, these nerves trigger the constriction of skin blood vessels to conserve heat, whereas in hot weather, they cause the vessels to expand (vasodilation) to dissipate excess heat. This work established him as a founder of experimental medicine and provided a key physiological explanation for how organisms maintain a constant internal state despite external fluctuations.21