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.'

"I have selected my own terms for the concepts that I have just defined. On many grounds I refrain from making any use of the good German terms 'Gedachtniss, Erinnerungsbild.' The first and chiefest ground is that for my purpose I should have to employ the German words in a much wider sense than what they usually convey, and thus leave the door open to countless misunderstandings and idle controversies. It would, indeed, even amount to an error of fact to give to the wider concept the name already current in the narrower sense--nay, actually limited, like 'Erinnerungsbild,' to phenomena of consciousness. . . . In Animals, during the course of history, one set of organs has, so to speak, specialised itself for the reception and transmission of stimuli--the Nervous System. But from this specialisation we are not justified in ascribing to the nervous system any monopoly of the function, even when it is as highly developed as in Man. . . . Just as the direct excitability of the nervous system has progressed in the history of the race, so has its capacity for receiving imprints; but neither susceptibility nor retentiveness is its monopoly; and, indeed, retentiveness seems inseparable from susceptibility in living matter."

Semen here takes the instance of stimulus and imprint actions affecting the nervous system of a dog

"who has up till now never experienced aught but kindness from the Lord of Creation, and then one day that he is out alone is pelted with stones by a boy. . . . Here he is affected at once by two sets of stimuli: (1) the optic stimulus of seeing the boy stoop for stones and throw them, and (2) the skin stimulus of the pain felt when they hit him. Here both stimuli leave their imprints; and the organism is permanently changed in relation to the recurrence of the stimuli. Hitherto the sight of a human figure quickly stooping had produced no constant special reaction. Now the reaction is constant, and may remain so till death. . . . The dog tucks in its tail between its legs and takes flight, often with a howl [as of] pain."

"Here we gain on one side a deeper insight into the imprint action of stimuli. It reposes on the lasting change in the conditions of the living matter, so that the repetition of the immediate or synchronous reaction to its first stimulus (in this case the stooping of the boy, the flying stones, and the pain on the ribs), no longer demands, as in the original state of indifference, the full stimulus a, but may be called forth by a partial or different stimulus, b (in this case the mere stooping to the ground). I term the influences by which such changed reaction are rendered possible, 'outcome-reactions,' and when such influences assume the form of stimuli, 'outcome-stimuli.'

They are termed "outcome" ("ecphoria") stimuli, because the author regards them and would have us regard them as the outcome, manifestation, or efference of an imprint of a previous stimulus. We have noted that the imprint is equivalent to the changed "physiological state" of Jennings. Again, the capacity for gaining imprints and revealing them by outcomes favourable to the individual is the "circular reaction" of Baldwin, but Semon gives no reference to either author. {0k}

In the preface to his first edition (reprinted in the second) Semon writes, after discussing the work of Hering and Haeckel:-

"The problem received a more detailed treatment in Samuel Butler's book, 'Life and Habit,' published in 1878. Though he only made acquaintance with Hering's essay after this publication, Butler gave what was in many respects a more detailed view of the coincidences of these different phenomena of organic reproduction than did Hering. With much that is untenable, Butler's writings present many a brilliant idea; yet, on the whole, they are rather a retrogression than an advance upon Hering. Evidently they failed to exercise any marked influence upon the literature of the day."

This judgment needs a little examination. Butler claimed, justly, that his "Life and Habit" was an advance on Hering in its dealing with questions of hybridity, and of longevity puberty and sterility. Since Semon's extended treatment of the phenomena of crosses might almost be regarded as the rewriting of the corresponding section of "Life and Habit" in the "Mneme" terminology, we may infer that this view of the question was one of Butler's "brilliant ideas." That Butler shrank from accepting such a formal explanation of memory as Hering did with his hypothesis should certainly be counted as a distinct "advance upon Hering," for Semon also avoids any attempt at an explanation of "Mneme." I think, however, we may gather the real meaning of Semon's strictures from the following passages:-

"I refrain here from a discussion of the development of this theory of Lamarck's by those Neo-Lamarckians who would ascribe to the individual elementary organism an equipment of complex psychical powers--so to say, anthropomorphic perception and volitions. This treatment is no longer directed by the scientific principle of referring complex phenomena to simpler laws, of deducing even human intellect and will from simpler elements. On the contrary, they follow that most abhorrent method of taking the most complex and unresolved as a datum, and employing it as an explanation. The adoption of such a method, as formerly by Samuel Butler, and recently by Pauly, I regard as a big and dangerous step backward" (ed. 2, pp. 380-1, note).

Thus Butler's alleged retrogressions belong to the same order of thinking that we have seen shared by Driesch, Baldwin, and Jennings, and most explicitly avowed, as we shall see, by Francis Darwin. Semon makes one rather candid admission, "The impossibility of interpreting the phenomena of physiological stimulation by those of direct reaction, and the undeception of those who had put faith in this being possible, have led many on the BACKWARD PATH OF VITALISM." Semon assuredly will never be able to complete his theory of "Mneme" until, guided by the experience of Jennings and Driesch, he forsakes the blind alley of mechanisticism and retraces his steps to reasonable vitalism.

But the most notable publications bearing on our matter are incidental to the Darwin Celebrations of 1908-9. Dr. Francis Darwin, son, collaborator, and biographer of Charles Darwin, was selected to preside over the Meeting of the British Association held in Dublin in 1908, the jubilee of the first publications on Natural Selection by his father and Alfred Russel Wallace. In this address we find the theory of Hering, Butler, Rignano, and Semon taking its proper place as a vera causa of that variation which Natural Selection must find before it can act, and recognised as the basis of a rational theory of the development of the individual and of the race. The organism is essentially purposive: the impossibility of devising any adequate accounts of organic form and function without taking account of the psychical side is most strenuously asserted. And with our regret that past misunderstandings should be so prominent in Butler's works, it was very pleasant to hear Francis Darwin's quotation from Butler's translation of Hering {0l} followed by a personal tribute to Butler himself.

In commemoration of the centenary of the birth of Charles Darwin and of the fiftieth anniversary of the publication of the "Origin of Species," at the suggestion of the Cambridge Philosophical Society, the University Press published during the current year a volume entitled "Darwin and Modern Science," edited by Mr. A. C. Seward, Professor of Botany in the University. Of the twenty-nine essays by men of science of the highest distinction, one is of peculiar interest to the readers of Samuel Butler: "Heredity and Variation in Modern Lights," by Professor W. Bateson, F.R.S., to whose work on "Discontinuous Variations" we have already referred. Here once more Butler receives from an official biologist of the first rank full recognition for his wonderful insight and keen critical power. This is the more noteworthy because Bateson has apparently no faith in the transmission of acquired characters; but such a passage as this would have commended itself to Butler's admiration:-

"All this indicates a definiteness and specific order in heredity, and therefore in variation. This order cannot by the nature of the case be dependent on Natural Selection for its existence, but must be a consequence of the fundamental chemical and physical nature of living things. The study of Variation had from the first shown that an orderliness of this kind was present. The bodies and properties of living things are cosmic, not chaotic. No matter how low in the scale we go, never do we find the slightest hint of a diminution in that all-pervading orderliness, nor can we conceive an organism existing for one moment in any other state."

We have now before us the materials to determine the problem of Butler's relation to biology and to biologists. He was, we have