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 Variation of Animals and Plants under Domestication grown too long, & I think I shall publish separately a very small volume, 'an essay on the origin of mankind'". This "essay" would become two books: "The Descent of Man, and Selection in Relation to Sex" (1871) and "The Expression of Emotions in Man and Animals" (1872). The book had been advertised as early as 1865 with the unwieldy title "Domesticated Animals and Cultivated Plants, or the Principles of Variation, Inheritance, Reversion, Crossing, Interbreeding, and Selection under Domestication" but Darwin agreed to the shorter "The Variation of Animals and Plants Under Domestication" suggested by the compositors. By May he