Fritz Müller supported Darwin’s theory of evolution.
Darwin incorporated some of Müller’s work in the second edition
of his Fertilisation of Orchids.
Darwin had Müller’s first paper in English translated and published,
and in 1864 Müller wrote Für Darwin to support Darwin’s
theory of evolution by natural selection.
Darwin wrote letters of support and offered Müller financial help
during Müller’s retirement.
See also in The book of science:
Readings on wikipedia: