A chance conversation with a friend of his father Augustin de Candolle convinced him to change his mind and pursue botany as a career. De Candolle dined with Darwin in London (Henslow another guest) and had an extensive correspondence with him (including about de Candolle’s ability to move his scalp muscularly). Wallace also corresponded, as did Galton — the latter engaging in a lively exchange of views through which de Candolle persuaded him that he’d overstressed heredity against environment. Gray was another correspondent, and met him three times. Nägeli was one of his students.