By September 1854 his second volume of "Barnacles" had been printed and dispatched, and he turned his attention to Species, telling his cousin William Darwin Fox that he planned to "view all facts that I can master..to see how far they favour or are opposed to the notion that wild species are mutable or immutable". All available information was examined for "hostile facts" and discussed with Hooker, who had resisted what he called Darwin's "Elastic theory" but who was now developing an "utter disbelief of my own Genera and species".