The theory of evolution was discredited around, IIRC, 1900

The only source I found semi-supporting that comes from a document which reads strangely, as if it is teaching the "controversy". Look at the wording:

By 1900, natural selection had been so discredited that few scientists accepted it as the mechanism of evolution. By all accounts, however, they all accepted the so-called “fact” that species evolve.

The so-called "fact"!