Arthur Milnes Marshall was a 19th-century scientist who gave lectures addressing the biological debates of his time. They covered topics including evolution, embryology, development and inheritance, with Charles Darwin’s name and those of other important biologists distributed liberally throughout. Marshall was a zoologist, embryologist, anatomist and Darwin enthusiast, as well as an accomplished mountaineer and sportsman. He was a humanist, an admired academic teacher and brilliant public educator. The lectures reveal his passion for communicating his subject, to his students and to the working men and women of Manchester, and they provide a remarkable snapshot of the state of biological science at the close of the 19th century. His death in 1893 aged only 41, on a climbing expedition in the Lake District, left a fascinating time capsule in the form of lectures from a critical transitional period in the history of biology. Evolution by natural selection was the established doctrine