Livingstone, David, 1813-1873. Letter to A[lexander] Haldane, 8 January 1858. Images copyright Royal College of Physicians and Surgeons of Glasgow. Creative Commons Attribution-NonCommercial 3.0 Unported (https://creativecommons.org/licenses/by-nc/3.0/). As relevant, copyright Dr. Neil Imray Livingstone Wilson. Creative Commons Attribution-NonCommercial 3.0 Unported (https://creativecommons.org/licenses/by-nc/3.0/). 