The Expression of the Emotions in Man and Animals research; simple psychology experiments on the recognition of emotions with his friends and family; and (borrowing from Duchenne de Boulogne, a physician at the Salpêtrière) the use of photographs in his presentation of scientific information. Publisher John Murray warned Darwin that including the photographs would "poke a hole in the profits" of the book; and "The Expression of the Emotions" is an important landmark in the history of book illustration. Background: In the weeks before Queen Victoria's coronation in 1838, Charles Darwin sought medical advice on his mysterious physical symptoms, and then travelled to Scotland for a period of rest
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