Francis Darwin (1848-1925): the biologist in the shadow of father Charles.

This year marks the 100th anniversary of the death of Sir Francis Darwin (1848-1925), the biologist/naturalist, musicologist, and biographer/philosopher of science in the shadow of father Charles (1809-1882). Francis was the seventh child and third son of the British couple. Here, we present a concise biography of Francis Darwin, based on his neglected "Recollections" published in his book Springtime and other Essays (1920). We summarize the scientific legacy of the younger Darwin with a focus on the "root-brain-hypotheses", as described in the 1880- "Darwin & Darwin book The Power of Movements in Plants, his extensive work on water-loss (transpiration) in plants via the stomata, and the Francis D.-papers on music instruments. In addition, we shed new light on the well-known "Darwin-Julius Sachs"-controversy of the 1880s. Finally, we document that the Biologist Francis Darwin was also a musician and polymath, with broad expertise in the natural sciences and the humanities alike.