“UNCONSCIOUS MEMORY” (1880).—We have already alluded to an anticipation of Butler’s main theses. In 1870 Dr. Ewald Hering, one of the most eminent physiologists of the day, Professor at Vienna, gave an Inaugural Address to the Imperial Royal Academy of Sciences: “Das Gedächtniss als allgemeine Funktion der organisirter Substanz” (“Memory as a Universal Function of Organised Matter”). When “Life and Habit” was well advanced, Francis Darwin, at the time a frequent visitor, called Butler’s attention to this essay, which he himself only knew from an article in “Nature.” Herein Professor E. Ray Lankester had referred to it with admiring sympathy in connection with its further development by Haeckel in a pamphlet entitled “Die Perigenese der Plastidule.” We may note, however, that in his collected Essays, “The Advancement of Science” (1890), Sir Ray Lankester, while including this Essay, inserts on the blank page {0b}—we had almost written “the white sheet”—at the back of it an apology for having ever advocated the possibility of the transmission of acquired characters. “Unconscious Memory” was largely written to show the relation of Butler’s views to Hering’s, and contains an exquisitely written translation of the Address. Hering does, indeed, anticipate Butler, and that in language far more suitable to the persuasion of the scientific public. It contains a subsidiary hypothesis that memory has for its mechanism special vibrations of the protoplasm, and the acquired capacity to respond to such vibrations once felt upon their repetition. I do not think that the theory gains anything by the introduction of this even as a mere formal hypothesis; and there is no evidence for its being anything more. Butler, however, gives it a warm, nay, enthusiastic, reception in Chapter V (Introduction to Professor Hering’s lecture), and in his notes to the translation of the Address, which bulks so large in this book, but points out that he was “not committed to this hypothesis, though inclined to accept it on a _prima facie_ view.” Later on, as we shall see, he attached more importance to it. The Hering Address is followed in “Unconscious Memory” by translations of selected passages from Von Hartmann’s “Philosophy of the Unconscious,” and annotations to explain the difference from this personification of “_The Unconscious_” as a mighty all-ruling, all-creating personality, and his own scientific recognition of the great part played by _unconscious processes_ in the region of mind and memory. These are the essentials of the book as a contribution to biological philosophy. The closing chapters contain a lucid statement of objections to his theory as they might be put by a rigid necessitarian, and a refutation of that interpretation as applied to human action.