Jennings makes no mention of questions of the theory of heredity. He has made some experiments on the transmission of an acquired character in Protozoa; but it was a mutilation-character, which is, as has been often shown, {0j} not to the point. * * * * * One of the most obvious criticisms of Hering’s exposition is based upon the extended use he makes of the word “Memory”: this he had foreseen and deprecated. “We have a perfect right,” he says, “to extend our conception of memory so as to make it embrace involuntary [and also unconscious] reproductions of sensations, ideas, perceptions, and efforts; but we find, on having done so, that we have so far enlarged her boundaries that she proves to be an ultimate and original power, the source and, at the same time, the unifying bond, of our whole conscious life.” (“Unconscious Memory,” p. 68.) This sentence, coupled with Hering’s omission to give to the concept of memory so enlarged a new name, clear alike of the limitations and of the stains of habitual use, may well have been the inspiration of the next work on our list. Richard Semon is a professional zoologist and anthropologist of such high status for his original observations and researches in the mere technical sense, that in these countries he would assuredly have been acclaimed as one of the Fellows of the Royal Society who were Samuel Butler’s special aversion. The full title of his book is “DIE MNEME als erhaltende Prinzip im Wechsel des organischen Geschehens” (Munich, Ed. 1, 1904; Ed. 2, 1908). We may translate it “MNEME, a Principle of Conservation in the Transformations of Organic Existence.” From this I quote in free translation the opening passage of Chapter II:— “We have shown that in very many cases, whether in Protist, Plant, or Animal, when an organism has passed into an indifferent state after the reaction to a stimulus has ceased, its irritable substance has suffered a lasting change: I call this after-action of the stimulus its ‘imprint’ or ‘engraphic’ action, since it penetrates and imprints itself in the organic substance; and I term the change so effected an ‘imprint’ or ‘engram’ of the stimulus; and the sum of all the imprints possessed by the organism may be called its ‘store of imprints,’ wherein we must distinguish between those which it has inherited from its forbears and those which it has acquired itself. Any phenomenon displayed by an organism as the result either of a single imprint or of a sum of them, I term a ‘mnemic phenomenon’; and the mnemic possibilities of an organism may be termed, collectively, its ‘MNEME.’