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,
Animals' Rights: Considered in Relation to Social Progress Salt is undoubtedly ahead of his age by many years." A new edition of the book was published in 1980 with a preface by the Australian philosopher Peter Singer, who is well known for his work on the ethics of treatment towards animals (specifically in the book "Animal Liberation"). The 1980 reissue prompted a review from Stephen Clark who praised Salt's book with some provisos. He states that Salt's attempt to blame the treatment of non-human animals on the theological doctrine of man having "dominion" over the natural world was mistaken. Animals' Rights: Considered in Relation to Social Progress Animals'