On Our Knowledge of the Causes of Organic Nature. Being Six Lectures to Working Men, Delivered at the Museum of Practical Geology. By Professor Huxley Published by Robert Hardwicke, 1863 First edition, 156pp, there are no adverts in this edition unlike other copies. 28 pages have been marked with pencil, either underlining or with brackets/lines down the side of the text. Front hinge is exposed to the webbing with 2.5\" separated at the bottom. Green embossed cloth boards are in very good condition except for small mark at bottom of spine (possible sticker has been removed).  Overall, in good condition.