In issuing this catalogue of the Library of Charles Darwin I wish to express to Mr Francis Darwin on behalf of the Staff of the Botany School our keen appreciation of his generosity. Rather more than a year ago Mr Darwin spoke to me of his intention to transfer the whole of his father's Library to the Botany School with the view of bequeathing it to the University. The books have been placed in a set of locked cases apart from the general departmental Library. From a purely historical point of view the Darwin Library is obviously of great interest, while the numerous notes scattered through many of the volumes add considerably to its scientific value. For the convenience of those engaged in research and as a means of adding to our knowledge of Darwin's scientific life, it seemed desirable to publish a catalogue of the books and pamphlets. The work has been done by Mr Rutherford of the University Library with thoroughness and care. Mr Francis Darwin has not only read the proofs but he willingly acceded to my request to write an Introduction supplementary to the account of his father's methods of work and treatment of books, with which readers of the Life and Letters are familiar.