INSTINCT AS INHERITED MEMORY
I have already alluded to M. Ribot's work on "Heredity," from which I will now take the following passages.
M. Ribot writes:-
"Instinct is innate, i.e., ANTERIOR TO ALL INDIVIDUAL EXPERIENCE." This I deny on grounds already abundantly apparent; but let it pass. "Whereas intelligence is developed slowly by accumulated experience, instinct is perfect from the first" ("Heredity," p. 14).
Obviously the memory of a habit or experience will not commonly be transmitted to offspring in that perfection which is called "instinct," till the habit or experience has been repeated in several generations with more or less uniformity; for otherwise the impression made will not be strong enough to endure through the busy and difficult task of reproduction. This of course involves that the habit shall have attained, as it were equilibrium with the creature's sense of its own needs, so that it shall have long seemed the best course possible, leaving upon the whole and under ordinary circumstances little further to be desired, and hence that it should have been little varied during many generations. We should expect that it would be transmitted in a more or less partial, varying, imperfect, and intelligent condition before equilibrium had been attained; it would, however, continually tend towards equilibrium, for reasons which will appear more fully later on.
When this stage has been reached, as regards any habit, the creature will cease trying to improve; on which the repetition of the habit will become stable, and hence become capable of more unerring transmission--but at the same time improvement will cease; the habit will become fixed, and be perhaps transmitted at an earlier and earlier age, till it has reached that date of manifestation which shall be found most agreeable to the other habits of the creature. It will also be manifested, as a matter of course, without further consciousness or reflection, for people cannot be always opening up settled questions; if they thought a matter over yesterday they cannot think it all over again to-day, but will adopt for better or worse the conclusion then reached; and this, too, even in spite sometimes of considerable misgiving, that if they were to think still further they could find a still better course. It is not, therefore, to be expected that "instinct" should show signs of that hesitating and tentative action which results from knowledge that is still so imperfect as to be actively self-conscious; nor yet that it should grow or vary, unless under such changed conditions as shall baffle memory, and present the alternative of either invention--that is to say, variation--or death. But every instinct must have poised through the laboriously intelligent stages through which human civilisations AND MECHANICAL INVENTIONS are now passing; and he who would study the origin of an instinct with its development, partial transmission, further growth, further transmission, approach to more unreflecting stability, and finally, its perfection as an unerring and unerringly transmitted instinct, must look to laws, customs, AND MACHINERY as his best instructors. Customs and machines are instincts AND ORGANS now in process of development; they will assuredly one day reach the unconscious state of equilibrium which we observe in the structures and instincts of bees and ants, and an approach to which may be found among some savage nations. We may reflect, however, not without pleasure, that this condition--the true millennium--is still distant. Nevertheless the ants and bees seem happy; perhaps more happy than when so many social questions were in as hot discussion among them, as other, and not dissimilar ones, will one day be amongst ourselves.
And this, as will be apparent, opens up the whole question of the stability of species, which we cannot follow further here, than to say, that according to the balance of testimony, many plants and animals do appear to have reached a phase of being from which they are hard to move--that is to say, they will die sooner than be at the pains of altering their habits--true martyrs to their convictions. Such races refuse to see changes in their surroundings as long as they can, but when compelled to recognise them, they throw up the game because they cannot and will not, or will not and cannot, invent. And this is perfectly intelligible, for a race is nothing but a long-lived individual, and like any individual, or tribe of men whom we have yet observed, will have its special capacities and its special limitations, though, as in the case of the individual, so also with the race, it is exceedingly hard to say what those limitations are, and why, having been able to go so far, it should go no further. Every man and every race is capable of education up to a certain point, but not to the extent of being made from a sow's ear into a silk purse. The proximate cause of the limitation seems to lie in the absence of the wish to go further; the presence or absence of the wish will depend upon the nature and surroundings of the individual, which is simply a way of saying that one can get no further, but that as the song (with a slight alteration) says:-
"Some breeds do, and some breeds don't, Some breeds will, but this breed won't, I tried very often to see if it would, But it said it really couldn't, and I don't think it could."
It may perhaps be maintained, that with time and patience, one might train a rather stupid plough-boy to understand the differential calculus. This might be done with the help of an inward desire on the part of the boy to learn, but never otherwise. If the boy wants to learn or to improve generally, he will do so in spite of every hindrance, till in time he becomes a very different being from what he was originally. If he does not want to learn, he will not do so for any wish of another person. If he feels that he has the power he will wish; or if he wishes, he will begin to think he has the power, and try to fulfil his wishes; one cannot say which comes first, for the power and the desire go always hand in hand, or nearly so, and the whole business is nothing but a most vicious circle from first to last. But it is plain that there is more to be said on behalf of such circles than we have been in the habit of thinking. Do what we will, we must each one of us argue in a circle of our own, from which, so long as we live at all, we can by no possibility escape. I am not sure whether the frank acceptation and recognition of this fact is not the best corrective for dogmatism that we are likely to find.
We can understand that a pigeon might in the course of ages grow to be a peacock if there was a persistent desire on the part of the pigeon through all these ages to do so. We know very well that this has not probably occurred in nature, inasmuch as no pigeon is at all likely to wish to be very different from what it is now. The idea of being anything very different from what it now is, would be too wide a cross with the pigeon's other ideas for it to entertain it seriously. If the pigeon had never seen a peacock, it would not be able to conceive the idea, so as to be able to make towards it; if, on the other hand, it had seen one, it would not probably either want to become one, or think that it would be any use wanting seriously, even though it were to feel a passing fancy to be so gorgeously arrayed; it would therefore lack that faith without which no action, and with which, every action, is possible.
That creatures have conceived the idea of making themselves like other creatures or objects which it was to their advantage or pleasure to resemble, will be believed by any one who turns to Mr. Mivart's "Genesis of Species," where he will find (chapter ii.) an account of some very showy South American butterflies, which give out such a strong odour that nothing will eat them, and which are hence mimicked both in appearance and flight by a very different kind of butterfly; and, again, we see that certain birds, without any particular desire of gain, no sooner hear any sound than they begin to mimick it, merely for the pleasure of mimicking; so we all enjoy to mimick, or to hear good mimicry, so also monkeys imitate the actions which they observe, from pure force of sympathy. To mimick, or to wish to mimick, is doubtless often one of the first steps towards varying in any given direction. Not less, in all probability, than a full twenty per cent. of all the courage and good nature now existing in the world, derives its origin, at no very distant date, from a desire to appear courageous and good-natured. And this suggests a work whose title should be "On the Fine Arts as bearing on the Reproductive System," of which the title must suffice here.
Against faith, then, and desire, all the "natural selection" in the world will not stop an amoeba from becoming an elephant, if a reasonable time be granted; without the faith and the desire, neither "natural selection" nor artificial breeding will be able to do much in the way of modifying any structure. When we have once thoroughly grasped the conception that we are all one creature, and that each one of us is many millions of years old, so that all the pigeons in the one line of an infinite number of generations are still one pigeon only--then we can understand that a bird, as different from a peacock as a pigeon is now, could yet have wandered on and on, first this way and then that, doing what it liked, and thought that it could do, till it found itself at length a peacock; but we cannot believe either that a bird like a pigeon should be able to apprehend any ideal so different from itself as a peacock, and make towards it, or that man, having wished to breed a bird anything like a peacock from a bird anything like a pigeon, would be able to succeed in accumulating accidental peacock-like variations till he had made the bird he was in search of, no matter in what number of generations; much less can we believe that the accumulation of small fortuitous variations by "natural selection" could succeed better. We can no more believe the above, than we can believe that a wish outside a plough-boy could turn him into a senior wrangler. The boy would prove to be too many for his teacher, and so would the pigeon for its breeder.
I do not forget that artificial breeding has modified the original type of the horse and the dog, till it has at length produced the dray-horse and the greyhound; but in each case man has had to get use and disuse--that is to say, the desires of the animal itself--to help him.
We are led, then, to the conclusion that all races have what for practical purposes may be considered as their limits, though there is no saying what those limits are, nor indeed why, in theory, there should be any limits at all, but only that there are limits in practice. Races which vary considerably must be considered as clever, but it may be speculative, people who commonly have a genius in some special direction, as perhaps for mimicry, perhaps for beauty, perhaps for music, perhaps for the higher mathematics, but seldom in more than one or two directions; while "inflexible organisations," like that of the goose, may be considered as belonging to people with one idea, and the greater tendency of plants and animals to vary under domestication may be reasonably compared with the effects of culture and education: that is to say, may be referred to increased range and variety of experience or perceptions, which will either cause sterility, if they be too unfamiliar, so as to be incapable of fusion with preceding ideas, and hence to bring memory to a sudden fault, or will open the door for all manner of further variation--the new ideas having suggested new trains of thought, which a clever example of a clever race will be only too eager to pursue.
Let us now return to M. Ribot. He writes (p. 14):- "The duckling hatched by the hen makes straight for water." In what conceivable way can we account for this, except on the supposition that the duckling knows perfectly well what it can, and what it cannot do with water, owing to its recollection of what it did when it was still one individuality with its parents, and hence, when it was a duckling before?
"The squirrel, before it knows anything of winter, lays up a store of nuts. A bird when hatched in a cage will, when given its freedom, build for itself a nest like that of its parents, out of the same materials, and of the same shape."
If this is not due to memory, even an imperfect explanation of what else it can be due to, "would be satisfactory."
"Intelligence gropes about, tries this way and that, misses its object, commits mistakes, and corrects them."
Yes. Because intelligence is of consciousness, and consciousness is of attention, and attention is of uncertainty, and uncertainty is of ignorance or want of consciousness. Intelligence is not yet thoroughly up to its business.
"Instinct advances with a mechanical certainty."
Why mechanical? Should not "with apparent certainty" suffice?
"Hence comes its unconscious character."
But for the word "mechanical" this is true, and is what we have been all along insisting on.
"It knows nothing either of ends, or of the means of attaining them; it implies no comparison, judgment, or choice."
This is assumption. What is certain is that instinct does not betray signs of self-consciousness as to its own knowledge. It has dismissed reference to first principles, and is no longer under the law, but under the grace of a settled conviction.
"All seems directed by thought."
Yes; because all HAS BEEN in earlier existences directed by thought.
"Without ever arriving at thought."
Because it has GOT PAST THOUGHT, and though "directed by thought" originally, is now travelling in exactly the opposite direction. It is not likely to reach thought again, till people get to know worse and worse how to do things, the oftener they practise them.
"And if this phenomenon appear strange, it must be observed that analogous states occur in ourselves. ALL THAT WE DO FROM HABIT-- WALKING, WRITING, OR PRACTISING A MECHANICAL ACT, FOR INSTANCE--ALL THESE AND MANY OTHER VERY COMPLEX ACTS ARE PERFORMED WITHOUT CONSCIOUSNESS.
"Instinct appears stationary. It does not, like intelligence, seem to grow and decay, to gain and to lose. It does not improve."
Naturally. For improvement can only as a general rule be looked for along the line of latest development, that is to say, in matters concerning which the creature is being still consciously exercised. Older questions are settled, and the solution must be accepted as final, for the question of living at all would be reduced to an absurdity, if everything decided upon one day was to be undecided again the next; as with painting or music, so with life and politics, let every man be fully persuaded in his own mind, for decision with wrong will be commonly a better policy than indecision--I had almost added with right; and a firm purpose with risk will be better than an infirm one with temporary exemption from disaster. Every race has made its great blunders, to which it has nevertheless adhered, inasmuch as the corresponding modification of other structures and instincts was found preferable to the revolution which would be caused by a radical change of structure, with consequent havoc among a legion of vested interests. Rudimentary organs are, as has been often said, the survivals of these interests--the signs of their peaceful and gradual extinction as living faiths; they are also instances of the difficulty of breaking through any cant or trick which we have long practised, and which is not sufficiently troublesome to make it a serious object with us to cure ourselves of the habit.
"If it does not remain perfectly invariable, at least it only varies within very narrow limits; and though this question has been warmly debated in our day, and is yet unsettled, we may yet say that in instinct immutability is the law, variation the exception."
This is quite as it should be. Genius will occasionally rise a little above convention, but with an old convention immutability will be the rule.
"Such," continues M. Ribot, "are the admitted characters of instinct."
Yes; but are they not also the admitted characters of actions that are due to memory?
At the bottom of p. 15, M. Ribot quotes the following from Mr. Darwin:-
"We have reason to believe that aboriginal habits are long retained under domestication. Thus with the common ass, we see signs of its original desert-life in its strong dislike to cross the smallest stream of water, and in its pleasure in rolling in the dust. The same strong dislike to cross a stream is common to the camel which has been domesticated from a very early period. Young pigs, though so tame, sometimes squat when frightened, and then try to conceal themselves, even in an open and bare place. Young turkeys, and occasionally even young fowls, when the hen gives the danger-cry, run away and try to hide themselves, like young partridges or pheasants, in order that their mother may take flight, of which she has lost the power. The musk duck in its native country often perches and roosts on trees, and our domesticated musk ducks, though sluggish birds, are fond of perching on the tops of barns, walls, &c. . . . We know that the dog, however well and regularly fed, often buries like the fox any superfluous food; we see him turning round and round on a carpet as if to trample down grass to form a bed. . . . In the delight with which lambs and kids crowd together and frisk upon the smallest hillock we see a vestige of their former alpine habits."
What does this delightful passage go to show, if not that the young in all these cases must still have a latent memory of their past existences, which is called into an active condition as soon as the associated ideas present themselves?
Returning to M. Ribot's own observations, we find he tells us that it usually requires three or four generations to fix the results of training, and to prevent a return to the instincts of the wild state. I think, however, it would not be presumptuous to suppose that if an animal after only three or four generations of training be restored to its original conditions of life, it will forget its intermediate training and return to its old ways, almost as readily as a London street Arab would forget the beneficial effects of a weeks training in a reformatory school, if he were then turned loose again on the streets. So if we hatch wild ducks' eggs under a tame duck, the ducklings "will have scarce left the egg-shell when they obey the instincts of their race and take their flight." So the colts from wild horses, and mongrel young between wild and domesticated horses, betray traces of their earlier memories.
On this M. Ribot says: "Originally man had considerable trouble in taming the animals which are now domesticated; and his work would have been in vain had not heredity" (memory) "come to his aid. It may be said that after man has modified a wild animal to his will, there goes on in its progeny a silent conflict between two heredities" (memories), "the one tending to fix the acquired modifications and the other to preserve the primitive instincts. The latter often get the mastery, and only after several generations is training sure of victory. But we may see that in either case heredity" (memory) "always asserts its rights."
How marvellously is the above passage elucidated and made to fit in with the results of our recognised experience, by the simple substitution of the word "memory" for "heredity."
"Among the higher animals"--to continue quoting--"which are possessed not only of instinct, but also of intelligence, nothing is more common than to see mental dispositions, which have evidently been acquired, so fixed by heredity, that they are confounded with instinct, so spontaneous and automatic do they become. Young pointers have been known to point the first time they were taken out, sometimes even better than dogs that had been for a long time in training. The habit of saving life is hereditary in breeds that have been brought up to it, as is also the shepherd dog's habit of moving around the flock and guarding it."
As soon as we have grasped the notion, that instinct is only the epitome of past experience, revised, corrected, made perfect, and learnt by rote, we no longer find any desire to separate "instinct" from "mental dispositions, which have evidently been acquired and fixed by heredity," for the simple reason that they are one and the same thing.
A few more examples are all that my limits will allow--they abound on every side, and the difficulty lies only in selecting--M. Ribot being to hand, I will venture to lay him under still further contributions.
On page 19 we find:- "Knight has shown experimentally the truth of the proverb, 'a good hound is bred so,' he took every care that when the pups were first taken into the field, they should receive no guidance from older dogs; yet the very first day, one of the pups stood trembling with anxiety, having his eyes fixed and all his muscles strained AT THE PARTRIDGES WHICH THEIR PARENTS HAD BEEN TRAINED TO POINT. A spaniel belonging to a breed which had been trained to woodcock-shooting, knew perfectly well from the first how to act like an old dog, avoiding places where the ground was frozen, and where it was, therefore, useless to seek the game, as there was no scent. Finally, a young polecat terrier was thrown into a state of great excitement the first time he ever saw one of these animals, while a spaniel remained perfectly calm.
"In South America, according to Roulin, dogs belonging to a breed that has long been trained to the dangerous chase of the peccary, when taken for the first time into the woods, know the tactics to adopt quite as well as the old dogs, and that without any instruction. Dogs of other races, and unacquainted with the tactics, are killed at once, no matter how strong they may be. The American greyhound, instead of leaping at the stag, attacks him by the belly, and throws him over, as his ancestors had been trained to do in hunting the Indians.
"Thus, then, heredity transmits modification no less than natural instincts."
Should not this rather be--"thus, then, we see that not only older and remoter habits, but habits which have been practised for a comparatively small number of generations, may be so deeply impressed on the individual that they may dwell in his memory, surviving the so-called change of personality which he undergoes in each successive generation"?
"There is, however, an important difference to be noted: the heredity of instincts admits of no exceptions, while in that of modifications there are many."
It may be well doubted how far the heredity of instincts admits of no exceptions; on the contrary, it would seem probable that in many races geniuses have from time to time arisen who remembered not only their past experiences, as far as action and habit went, but have been able to rise in some degree above habit where they felt that improvement was possible, and who carried such improvement into further practice, by slightly modifying their structure in the desired direction on the next occasion that they had a chance of dealing with protoplasm at all. It is by these rare instances of intellectual genius (and I would add of moral genius, if many of the instincts and structures of plants and animals did not show that they had got into a region as far above morals--other than enlightened self-interest--as they are above articulate consciousness of their own aims in many other respects)--it is by these instances of either rare good luck or rare genius that many species have been, in all probability, originated or modified. Nevertheless inappreciable modification of instinct is, and ought to be, the rule.
As to M. Ribot's assertion, that to the heredity of modifications there are many exceptions, I readily agree with it, and can only say that it is exactly what I should expect; the lesson long since learnt by rote, and repeated in an infinite number of generations, would be repeated unintelligently, and with little or no difference, save from a rare accidental slip, the effect of which would be the culling out of the bungler who was guilty of it, or from the still rarer appearance of an individual of real genius; while the newer lesson would be repeated both with more hesitation and uncertainty, and with more intelligence; and this is well conveyed in M. Ribot's next sentence, for he says--"It is only when variations have been firmly rooted; when having become organic, they constitute a second nature, which supplants the first; when, like instinct, they have assumed a mechanical character, that they can be transmitted."
How nearly M. Ribot comes to the opinion which I myself venture to propound will appear from the following further quotation. After dealing with somnambulism, and saying, that if somnambulism were permanent and innate, it would be impossible to distinguish it from instinct, he continues:-
"Hence it is less difficult than is generally supposed, to conceive how intelligence may become instinct; we might even say that, leaving out of consideration the character of innateness, to which we will return, we have seen the metamorphosis take place. THERE CAN THEN BE NO GROUND FOR MAKING INSTINCT A FACULTY APART, sui generis, a phenomenon so mysterious, so strange, that usually no other explanation of it is offered but that of attributing it to the direct act of the Deity. This whole mistake is the result of a defective psychology which makes no account of the unconscious activity of the soul."
We are tempted to add--"and which also makes no account of the bona fide character of the continued personality of successive generations."
"But we are so accustomed," he continues, "to contrast the characters of instinct with those of intelligence--to say that instinct is innate, invariable, automatic, while intelligence is something acquired, variable, spontaneous--that it looks at first paradoxical to assert that instinct and intelligence are identical.
"It is said that instinct is innate. But if, on the one hand, we bear in mind that many instincts are acquired, and that, according to a theory hereafter to be explained" (which theory, I frankly confess, I never was able to get hold of), "ALL INSTINCTS ARE ONLY HEREDITARY HABITS" (italics mine); "if, on the other hand, we observe that intelligence is in some sense held to be innate by all modern schools of philosophy, which agree to reject the theory of the tabula rasa" (if there is no tabula rasa, there is continued psychological personality, or words have lost their meaning), "and to accept either latent ideas, or a priori forms of thought" (surely only a periphrasis for continued personality and memory) "or pre-ordination of the nervous system and of the organism; IT WILL BE SEEN THAT THIS CHARACTER OF INNATENESS DOES NOT CONSTITUTE AN ABSOLUTE DISTINCTION BETWEEN INSTINCT AND INTELLIGENCE.
"It is true that intelligence is variable, but so also is instinct, as we have seen. In winter, the Rhine beaver plasters his wall to windward; once he was a builder, now a burrower; once he lived in society, now he is solitary. Intelligence itself can scarcely be more variable . . . instinct may be modified, lost, reawakened.
"Although intelligence is, as a rule, conscious, it may also become unconscious and automatic, without losing its identity. Neither is instinct always so blind, so mechanical, as is supposed, for at times it is at fault. The wasp that has faultily trimmed a leaf of its paper begins again. The bee only gives the hexagonal form to its cell after many attempts and alterations. It is difficult to believe that the loftier instincts" (and surely, then, the more recent instincts) "of the higher animals are not accompanied BY AT LEAST A CONFUSED CONSCIOUSNESS. There is, therefore, no absolute distinction between instinct and intelligence; there is not a single characteristic which, seriously considered, remains the exclusive property of either. The contrast established between instinctive acts and intellectual acts is, nevertheless, perfectly true, but only when we compare the extremes. AS INSTINCT RISES IT APPROACHES INTELLIGENCE--AS INTELLIGENCE DESCENDS IT APPROACHES INSTINCT."
M. Ribot and myself (if I may venture to say so) are continually on the verge of coming to an understanding, when, at the very moment that we seem most likely to do so, we fly, as it were, to opposite poles. Surely the passage last quoted should be, "As instinct falls," i.e., becomes less and less certain of its ground, "it approaches intelligence; as intelligence rises," i.e., becomes more and more convinced of the truth and expediency of its convictions-- "it approaches instinct."
Enough has been said to show that the opinions which I am advancing are not new, but I have looked in vain for the conclusions which, it appears to me, M. Ribot should draw from his facts; throughout his interesting book I find the facts which it would seem should have guided him to the conclusions, and sometimes almost the conclusions themselves, but he never seems quite to have reached them, nor has he arranged his facts so that others are likely to deduce them, unless they had already arrived at them by another road. I cannot, however, sufficiently express my obligations to M. Ribot.
I cannot refrain from bringing forward a few more instances of what I think must be considered by every reader as hereditary memory. Sydney Smith writes:-
"Sir James Hall hatched some chickens in an oven. Within a few minutes after the shell was broken, a spider was turned loose before this very youthful brood; the destroyer of flies had hardly proceeded more than a few inches, before he was descried by one of these oven- born chickens, and, at one peck of his bill, immediately devoured. This certainly was not imitation. A female goat very near delivery died; Galen cut out the young kid, and placed before it a bundle of hay, a bunch of fruit, and a pan of milk; the young kid smelt to them all very attentively, and then began to lap the milk. This was not imitation. And what is commonly and rightly called instinct, cannot be explained away, under the notion of its being imitation" (Lecture xvii. on Moral Philosophy).
It cannot, indeed, be explained away under the notion of its being imitation, but I think it may well be so under that of its being memory.
Again, a little further on in the same lecture, as that above quoted from, we find:-
"Ants and beavers lay up magazines. Where do they get their knowledge that it will not be so easy to collect food in rainy weather, as it is in summer? Men and women know these things, because their grandpapas and grandmammas have told them so. Ants hatched from the egg artificially, or birds hatched in this manner, have all this knowledge by intuition, without the smallest communication with any of their relations. Now observe what the solitary wasp does; she digs several holes in the sand, in each of which she deposits an egg, though she certainly knows not (?) that an animal is deposited in that egg, and still less that this animal must be nourished with other animals. She collects a few green flies, rolls them up neatly in several parcels (like Bologna sausages), and stuffs one parcel into each hole where an egg is deposited. When the wasp worm is hatched, it finds a store of provision ready made; and what is most curious, the quantity allotted to each is exactly sufficient to support it, till it attains the period of wasphood, and can provide for itself. This instinct of the parent wasp is the more remarkable as it does not feed upon flesh itself. Here the little creature has never seen its parent; for by the time it is born, the parent is always eaten by sparrows; and yet, without the slightest education, or previous experience, it does everything that the parent did before it. Now the objectors to the doctrine of instinct may say what they please, but young tailors have no intuitive method of making pantaloons; a new-born mercer cannot measure diaper; nature teaches a cook's daughter nothing about sippets. All these things require with us seven years' apprenticeship; but insects are like Moliere's persons of quality--they know everything (as Moliere says), without having learnt anything. 'Les gens de qualite savent tout, sans avoir rien appris.'"
How completely all difficulty vanishes from the facts so pleasantly told in this passage when we bear in mind the true nature of personal identity, the ordinary working of memory, and the vanishing tendency of consciousness concerning what we know exceedingly well.
My last instance I take from M. Ribot, who writes:- "Gratiolet, in his Anatomie Comparee du Systeme Nerveux, states that an old piece of wolf's skin, with the hair all worn away, when set before a little dog, threw the animal into convulsions of fear by the slight scent attaching to it. The dog had never seen a wolf, and we can only explain this alarm by the hereditary transmission of certain sentiments, coupled with a certain perception of the sense of smell" ("Heredity," p. 43).
I should prefer to say "we can only explain the alarm by supposing that the smell of the wolf's skin"--the sense of smell being, as we all know, more powerful to recall the ideas that have been associated with it than any other sense--"brought up the ideas with which it had been associated in the dog's mind during many previous existences"-- he on smelling the wolf's skin remembering all about wolves perfectly well.