The Expression of the Emotions in Man and Animals in the field of comparative psychology and his impact on academic psychology was muted, partly because of the widespread influence of the behaviourist school during the twentieth century. The lavish style of biological illustration was followed in work on animal locomotion by photographer Eadweard Muybridge (1830–1904)(leading to cinematography), and by the Scottish naturalist James Bell Pettigrew (1832–1908); in the extensively (and controversially) illustrated works of the evolutionary biologist Ernst Haeckel; and – to a lesser extent – in D'Arcy Thompson's "On Growth and Form" (1917). Darwin's ideas were followed up in William James' "What Is An Emotion ?" (1884); and,
The Formation of Vegetable Mould through the Action of Worms went the less controversial direction of the lowly worm. His network of correspondents and fans responded to his interest and "earthworm anecdotes began surfacing in his mountain of mail". He had been interested in earthworms "since his first fishing days at The Mount and flirting days at Maer". Still, other work constrained him. Broken off from "Descent", he had to finish his next work "The Expression of the Emotions in Man and Animals". By 1876, with his first grandson on the way, he felt his writing life was nearly over, with so much unfinished. He wanted to write on earthworms