Working in night shifts

Candolle recognized that multiple species may develop similar characteristics that did not appear in a common evolutionary ancestor; this was later termed analogy. During his work with plants, Candolle noticed that plant leaf movements follow a near-24-hour cycle in constant light, suggesting that an internal biological clock exists. Though many scientists doubted Candolle's findings, experiments over a century later demonstrated that ″the internal biological clock″ indeed exists.