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Fig.1.	Part of Secondary Feather of Argus Pheasant.
Fig.2.	Ditto Wing-feather of ditto.
Fig.3.	Diagram of Butterfly's Wing.
Fig.4.	Python.
Fig.5.	Tiger's Skin.
Fig.6.	Ditto.
Fig.7.	Tiger's Head, side view.
Fig.8.	Ditto, crown.
Fig.9.	Leopard's Skin.
Fig. 10.	Ditto.
Fig. 11.	Leopard's Head, side view.
Fig. 12.	Ditto, crown.
Fig. 13.	Lynx' Skin.
Fig. 14.	Ditto.
Fig. 15.	Ocelot.
Fig. 16.	Badger.
Fig. 17.	Begonia Leaf.

DESCRIPTION OF PLATES.

Plate I. p. 28.	Kallima Inachus, the Indian Leaf Butterfly. Fig. 1. With wings expanded. Fig. 2. Two Butterflies at rest, showing their exact resemblance to dead leaves. This insect affords one of the best examples of protective resemblance.
Plate II. p. 30.	Illustration of mimicry in butterflies. Fig. 1. Male of Papilio merope. Fig. 2. Female of ditto mimicking Fig. 3. Fig. 3. Danais niavius. On the African continent both species occur, but in Madagascar D. niavius is wanting, and the female P. merope is coloured like the male.
Plate III. p. 40.	Fig. 1. Gonepteryx Cleopatra. Fig. 2. Gonepteryx rhamni, male. Note.—The orange spot in Fig. 2 has spread over the wing in Fig. 1. Fig. 3. Vanessa Antiopa. Fig. 4. Panopœa hirta. Fig. 5. Acrea gea. These two last belong to widely different genera, but are admirable examples of mimicry.
Plate IV. p. 42.	Fig. 1. Leucophasia Sinapis. Fig. 2. Ditto, var. diniensis. Fig. 3. Anthocaris cardamines, male. Fig. 4. Ditto, female. Fig. 5. Anthocaris belemia. Fig. 6. Anthocaris belia. Fig. 7. Ditto, var. simplonia. Fig. 8. Anthocaris eupheno, female. Fig. 9. Ditto, male. Fig. 10. Anthocaris euphemoides. Fig. 11. Papilio machaon. Fig. 12. Papilio podalirius. Fig. 13. Pieris napi, summer form. Fig. 14. Ditto, winter form. Fig. 15. Ditto, var. bryoniæ (alpine form). Fig. 16. Ditto, summer form, underside. Fig. 17. Ditto, winter form, underside. Fig. 18. Ditto, var. bryoniæ, underside. Figs. 13–18 illustrate admirably the variations of the yellow and black in the same species.
Plate V. p. 44.	Fig. 1. Araschnia prorsa, male. Fig. 2. Ditto, female. Fig. 3. Araschnia levana, female. Fig. 4. Ditto, male. Fig. 5. Paragra ægeria. Fig. 6. Araschnia porima. Fig. 7. Ditto, var. meione. Fig. 8. Grapta interrogationis. Fig. 9. Ditto. Fig. 10. Ditto. Fig. 11. Papilio Ajax, var. Walshii. Fig. 12. Ditto, var. telamonides. Fig. 13. Ditto, var. Marcellus. Figs. 1–5 are all one species; levana being the winter form, prorsa the summer form, and porima intermediate. Similarly 6–7 are the same species, meione being the southern form. So with 8–9 and 11–13, which are only seasonal varieties. Here we can actually trace the way in which varieties are formed. See Weismann's work, cited in the text.
Plate VI. p. 62.	Syncoryne pulchella, magnified. After Professor Allman. Gymnoblastic or Tubularian Hydroids. Ray Soc., 1871, pl. vi., figs. 1 and 3. Fig. 1. A planoblast as seen passively floating in the water after liberation. Fig. 2. The entire hydrosoma of syncoryne. a. The spadix. b. The medusæ or planoblasts in various stages of development.
Plate VII. p. 80.	Fig. 1. Deilephila galii, immature. Fig. 2. Ditto brown variety, adult. Fig. 3. Deilephila euphorbiæ. Fig. 4. Sphinx ligustri. Fig. 5. Deilephila euphorbiæ, dorsal view. Fig. 6. Orgyia antiqua. Fig. 7. Abraxas grossulariata. Fig. 8. Bombyx neustria. Fig. 9. Callimorpha dominula. Fig. 10. Euchelia jacobæa. Fig. 11. Papilio machaon.
	SPIDERS.
Plate VIII. p. 84.	Fig. 1. Segestria senoculata, female. Fig. 2. Sparassus smaragdulus, male. Fig. 3. Lycosa piscatoria, female. Fig. 4. ——andrenivora, male. Fig. 5. ————female. Fig. 6. ——allodroma, male. Fig. 7. ——agretyca, male. Fig. 8. ——allodroma, female. Fig. 9. Diagram of Lycosa, showing form and position of vessels. After Gegenbaur. Fig. 10. Lycosa campestris, female. Fig. 11. Thomisus luctuosus, male. Fig. 12. Salticus scenicus, female. Fig. 13. Lycosa rapax, female. Fig. 14. ——latitans, female. Fig. 15. Theridion pictum, female. Fig. 16. Lycosa picta, female. Fig. 17. ————male. All the above are British species, and copied from Blackwell's "Spiders of Great Britain and Ireland." Ray Soc., 1862.
	FISHES.
Plate IX. p. 88.	Fig. 1. Windermere Char. Salmo Willughbii. A species peculiar to our North of England lakes. Fig. 2. Perch, Perca fluviatilis, showing the modified rib-like markings.
	SUNBIRDS.
Plate X. p. 90.	Fig. 1. Nectarinea chloropygia. Fig. 2. Nectarinea christinæ. These birds illustrate regional colouration well.
	LEAVES.
Plate XI. p. 95.	Fig. 1. Horse Chestnut, Æschulus hippocastanum, decaying. Fig. 2. Coleus. Fig. 3. Begonia rex. Fig. 4. Begonia. Fig. 5. Caladium bicolor. Fig. 6. Anœchtochilus xanthophyllus.
	FLOWERS.
Plate XII. p. 96.	Fig. 1. Gloxinia, with 5 petals, showing uneven colouring. Fig. 2. Gloxinia, with 6 petals, showing regular colouring. Figs. 3 and 4. Pelargoniums, showing the variation of the dark markings with the different sized petals.

COLOURATION IN ANIMALS AND PLANTS.

CHAPTER I.

Introduction.

B

BEFORE Darwin published his remarkable and memorable work on the Origin of Species, the decoration of animals and plants was a mystery as much hidden to the majority as the beauty of the rainbow ere Newton analysed the light. That the world teemed with beauty in form and colour was all we knew; and the only guess that could be made as to its uses was the vague and unsatisfactory suggestion that it was appointed for the delight of man.

Why, if such was the case, so many flowers were "born to blush unseen," so many insects hidden in untrodden forests, so many bright-robed creatures buried in the depths of the sea, no man could tell. It seemed but a poor display of creative intelligence to lavish for thousands of years upon heedless savage eyes such glories as are displayed by the forests of Brazil; and the mind recoiled from the suggestion that such could ever have been the prime intention.

But with the dawn of the new scientific faith, light began to shine upon these and kindred questions; nature ceased to appear a mass of useless, unconnected facts, and ornamentation appeared in its true guise as of extreme importance to the beings possessing it. It was the theory of descent with modification that threw this light upon nature.

This theory, reduced to its simplest terms, is that species, past and present, have arisen from the accumulation by inheritance of minute differences of form, structure, colour, or habit, giving to the individual a better chance, in the struggle for existence, of obtaining food or avoiding danger. It is based on a few well-known and universally admitted facts or laws of nature: namely, the law of multiplication in geometrical progression causing the birth of many more individuals than can survive, leading necessarily to the struggle for existence; the law of heredity, in virtue of which the offspring resembles its parents; the law of variation, in virtue of which the offspring has an individual character slightly differing from its parents.

To illustrate these laws roughly we will take the case of a bird, say, the thrush. The female lays on the average five eggs, and if all these are hatched, and the young survive, thrushes would be as seven to two times as numerous in the next year. Let two of these be females, and bring up each five young; in the second year we shall have seventeen thrushes, in the third thirty-seven, in the fourth seventy-seven, and so on. Now common experience tells us not merely that such a vast increase of individuals does not take place, but can never do so, as in a very few years the numbers would be so enormously increased that food would be exhausted.

On the other hand, we know that the numbers of individuals remain practically the same. It follows, then, that of every five eggs four fail to arrive at maturity; and this rigorous destruction of individuals is what is known as the struggle for existence. If, instead of a bird, we took an insect, laying hundreds of eggs, a fish, laying thousands, or a plant, producing still greater quantities of seed, we should find the extermination just as rigorous, and the numbers of individuals destroyed incomparably greater. Darwin has calculated that from a single pair of elephants nearly nineteen millions would be alive in 750 years if each elephant born arrived at maturity, lived a hundred years, and produced six young—and the elephant is the slowest breeder of all animals.

The struggle for existence, then, is a real and potent fact, and it follows that if, from any cause whatever, a being possesses any power or peculiarity that will give it a better chance of survival over its fellows—be that power ever so slight—it will have a very decided advantage.

Now it can be shown that no two individuals are exactly alike, in other words, that variation is constantly taking place, and that no animal or plant preserves its characters unmodified. This we might have expected if we attentively consider how impossible it is for any two individuals to be subjected to exactly the same conditions of life and habit. But for the proofs of variability we have not to rely upon theoretical reasoning. No one can study, even superficially, any class or species without daily experiencing the conviction that no two individuals are alike, and that variation takes place in almost every conceivable direction.

Granted then the existence of the struggle for existence and the variability of individuals, and granting also that if any variation gives its possessor a firmer hold upon life, it follows as a necessity that the most favoured individuals will have the best chance of surviving and leaving descendants, and by the law of heredity, we know these offspring will tend to inherit the characters of their parents. This action is often spoken of as the preservation of favoured races, and as the survival of the fittest.

The gradual accumulation of beneficial characters will give rise in time to new varieties and species; and in this way primarily has arisen the wonderful diversity of life that now exists. Such, in barest outline, is the theory of descent with modification.

Let us now see in what way this theory has been applied to colouration. The colours, or, more strictly, the arrangement of colours, in patterns is of several kinds, viz.:—

1. General Colouration, or such as appears to have no very special function as colour. We find this most frequently in the vegetable kingdom, as, for instance, the green hue of leaves, which, though it has a most valuable function chemically has no particular use as colour, so far as we can see.

2. Distinctive Colouration, or the arrangement of colours in different patterns or tints corresponding to each species. This is the most usual style of colouring, and the three following kinds are modifications of it. It is this which gives each species its own design, whether in animals or plants.

3. Protective Resemblance, or the system of colouring which conceals the animal from its prey, or hides the prey from its foe. Of this class are the green hues of many caterpillars, the brown tints of desert birds, and the more remarkable resemblances of insects to sticks and leaves.

4. Mimetic Colouration, or the resemblance of one animal to another. It is always the resemblance of a rare species, which is the favourite food of some creature, to a common species nauseous to the mimicker's foe. Of this character are many butterflies.

5. Warning Colours, or distinctive markings and tints rendering an animal conspicuous, and, as it were, proclaiming noli me tangere to its would-be attackers.

6. Sexual Colours, or particular modifications of colour in the two sexes, generally taking the form of brilliancy in the male, as in the peacock and birds of paradise.

Under one or other of these headings most schemes of colouration will be found to arrange themselves.

At the outset, and confining ourselves to the animal kingdom for the present, bearing in mind the fierce intensity of the struggle for life, it would seem that any scheme of colour that would enable its possessor to elude its foes or conceal itself from its prey, would be of vital importance. Hence we might infer that protective colouring would be a very usual phenomenon; and such we find to be the case. In the sea we have innumerable instances of protective colouring. Fishes that lie upon the sandy bottom are sand-coloured, like soles and plaice, in other orders we find the same hues in shrimps and crabs, and a common species on our shores (Carcinus mænas) has, just behind the eyes, a little light irregular patch, so like the shell fragments around that when it hides in the sand, with eyes and light spot alone showing, it is impossible to distinguish it.

The land teems with protective colours. The sombre tints of so many insects, birds and animals are cases in point, as are the golden coat of the spider that lurks in the buttercup, and the green mottlings of the underwings of the orange-tip butterfly. Where absolute hiding is impossible, as on the African desert, we find every bird and insect, without exception, assimilating the colour of the sand.

But if protective colour is thus abundant, it is no less true that colour of the most vivid description has arisen for the sole purpose of attracting notice. We observe this in the hues of many butterflies, in the gem-like humming birds, in sun-birds, birds of paradise, peacocks and pheasants. To see the shining metallic blue of a Brazilian Morpho flashing in the sun, as it lazily floats along the forest glades, is to be sure that in such cases the object of the insect is to attract notice.

These brilliant hues, when studied, appear to fall into two classes, having very diverse functions, namely Sexual and Warning Colours.

Protection is ensured in many ways, and among insects one of the commonest has been the acquisition of a nauseous flavour. This is often apparent even to our grosser senses; and the young naturalist who captures his first crimson-and-green Burnet Moth or Scarlet Tiger, becomes at once aware of the existence of a fetid greasy secretion. This the insectivorous birds know so well that not one will ever eat such insects. But unless there were some outward and visible sign of this inward and sickening taste, it would little avail the insect to be first killed and then rejected. Hence these warning colours—they as effectively signal danger as the red and green lamps on our railways.

It may here be remarked that wherever mimickry occurs in insects, the species mimicked is always an uneatable one, and the mimicker a palatable morsel. It is nature's way of writing "poison" on her jam-pots.

The other class of prominent colours—the Sexual—have given rise to two important theories, the one by Darwin, the counter-theory by Wallace.

Darwin's theory of Sexual Selection is briefly this:—He points out in much detail how the male is generally the most powerful, the most aggressive, the most ardent, and therefore the wooer, while the female is, as a rule, gentler, smaller, and is wooed or courted. He brings forward an enormous mass of well-weighed facts to show, for example, how often the males display their plumes and beauties before their loves in the pairing season, and his work is a long exposition of the truth that Tennyson proclaimed when he wrote:—

"In the spring a fuller crimson comes upon the robin's breast,

In the spring the wanton lapwing gets himself another crest,

In the spring a livelier iris changes on the burnished dove,

In the spring the young man's fancy lightly turns to thoughts of love."

That birds are eminently capable of appreciating beauty is certain, and numerous illustrations are familiar to everyone. Suffice it here to notice the pretty Bower Birds of Australia, that adorn their love arbours with bright shells and flowers, and show as unmistakable a delight in them as the connoisseur among his art treasures.

From these and kindred facts Darwin draws the conclusion that the females are most charmed with, and select the most brilliant males, and that by continued selection of this character, the sexual hues have been gradually evolved.

To this theory Wallace takes exception. Admitting, as all must, the fact of sexually distinct ornamentation, he demurs to the conclusion that they have been produced by sexual selection.

In the first place, he insists upon the absence of all proof that the least attractive males fail to obtain partners, without which the theory must fail. Next he tells us that it was the case of the Argus pheasant, so admirably worked out by Darwin, that first shook his faith in sexual selection. Is it possible, he asks, that those exquisite eye-spots, shaded "like balls lying loose within sockets" (objects of which the birds could have had no possible experience) should have been produced … "through thousands and tens of thousands of female birds, all preferring those males whose markings varied slightly in this one direction, this uniformity of choice continuing through thousands and tens of thousands of generations"?[1]

As an alternative explanation, he would advance no new theory, but simply apply the known laws of evolution. He points out, and dwells upon, the high importance of protection to the female while sitting on the nest. In this way he accounts for the more sombre hues of the female; and finds strong support in the fact that in those birds in which the male undertakes the household duties, he is of a domestic dun colour, and his gad-about-spouse is bedizened like a country-girl at fair time.

With regard to the brilliant hues themselves, he draws attention to the fact that depth and intensity of colour are a sign of vigour and health—that the pairing time is one of intense excitement, and that we should naturally expect to find the brightest hues then displayed. Moreover, he shows—and this is most important to us—that "the most highly-coloured and most richly varied markings occur on those parts which have undergone the greatest modification, or have acquired the most abnormal development."[2]

It is not our object to discuss these rival views; but they are here laid down in skeleton, that the nature of the problem of the principles of colouration may be easily understood.

Seeing, then, how infinitely varied is colouration, and how potently selection has modified it, the question may be asked, "Is it possible to find any general system or law which has determined the main plan of decoration, any system which underlies natural selection, and through which it works"? We venture to think there is; and the object of this work is to develop the laws we have arrived at after several years of study.

CHAPTER II.

Inherited Memory.

M

MANY of our observations seemed to suggest a quasi-intelligent action on the part of the beings under examination; and we were led, early in the course of our studies, to adopt provisionally the hypothesis that memory was inherited—that the whole was consequently wiser than its parts, the species wiser than the individual, the genus wiser than the species.

One illustration will suffice to show the possibility of memory being inherited. Chickens, as a rule, are hatched with a full knowledge of how to pick up a living, only a few stupid ones having to be taught by the mother the process of pecking. When eggs are hatched artificially, ignorant as well as learned chicks are produced, and the less intelligent, having no hen instructor, would infallibly die in the midst of plenty. But if a tapping noise, like pecking, be made near them, they hesitate awhile, and then take to their food with avidity. Here the tapping noise seems certainly to have awakened the ancestral memory which lay dormant.

It may be said all this is habit. But what is habit? Is it any explanation to say a creature performs a given action by habit? or is it not rather playing with a word which expresses a phenomenon without explaining it? Directly we bring memory into the field we get a real explanation. A habit is acquired by repetition, and could not arise if the preceding experience were forgotten. Life is largely made up of repetition, which involves the formation of habits; and, indeed, everyone's experience (habit again) shows that life only runs smoothly when certain necessary habits have been acquired so perfectly as to be performed without effort. A being at maturity is a great storehouse of acquired habits; and of these many are so perfectly acquired, i.e., have been performed so frequently, that the possessor is quite unconscious of possessing them.

Habit tends to become automatic; indeed, a habit can hardly be said to be formed until it is automatic. But habits are the result of experience and repetition, that is, have arisen in the first instance by some reasoning process; and reasoning implies consciousness. Nevertheless, the action once thought out, or reasoned upon, requires less conscious effort on a second occasion, and still less on a third, and so on, until the mere occurrence of given conditions is sufficient to ensure immediate response without conscious effort, and the action is performed mechanically or automatically: it is now a true habit. Habit, then, commences in consciousness and ends in unconsciousness. To say, therefore, when we see an action performed without conscious thought, that consciousness has never had part in its production, is as illogical as to say that because we read automatically we can never have learned to read.

The thorough appreciation of this principle is absolutely essential to the argument of this work; for to inherited memory we attribute not only the formation of habits and instincts, but also the modification of organs, which leads to the formation of new species. In a word, it is to memory we attribute the possibility of evolution, and by it the struggle for existence is enabled to re-act upon the forms of life, and produce the harmony we see in the organic world.

Our own investigations had led us very far in this direction; but we failed to grasp the entire truth until Mr. S. Butler's remarkable work, "Life and Habit," came to our notice. This valuable contribution to evolution smoothed away the whole of the difficulties we had experienced, and enabled us to propound the views here set forth with greater clearness than had been anticipated.

The great difficulty in Mr. Darwin's works is the fact that he starts with variations ready made, without trying, as a rule, to account for them, and then shows that if these varieties are beneficial the possessor has a better chance in the great struggle for existence, and the accumulation of such variations will give rise to new species. This is what he means by the title of his work, "The Origin of Species by means of Natural Selection or the Preservation of Favoured Races in the Struggle for Life." But this tells us nothing whatever about the origin of species. As Butler puts it, "Suppose that it is an advantage to a horse to have an especially broad and hard hoof: then a horse born with such a hoof will, indeed, probably survive in the struggle for existence; but he was not born with the larger and harder hoof because of his subsequently surviving. He survived because he was born fit—not he was born fit because he survived. The variation must arise first and be preserved afterwards." [3]

Mr. Butler works out with admirable force the arguments, first, that habitual action begets unconsciousness; second, that there is a unity of personality between parent and offspring; third, that there is a memory of the oft-repeated acts of past existences, and, lastly, that there is a latency of that memory until it is re-kindled by the presence of associated ideas.

As to the first point, we need say no more, for daily experience confirms it; but the other points must be dealt with more fully.

Mr. Butler argues for the absolute identity of the parent and offspring; and, indeed, this is a necessity. Personal identity is a phrase, very convenient, it is true, but still only a provisional mode of naming something we cannot define. In our own bodies we say that our identity remains the same from birth to death, though we know that our bodily particles are ever changing, that our habits, thoughts, aspirations, even our features, change—that we are no more really the same person than the ripple over a pebble in a brook is the same from moment to moment, though its form remains. If our personal identity thus elude our search in active life, it certainly becomes no more tangible if we trace existence back into pre-natal states. We are, in one sense, the same individual; but, what is equally important, we were part of our mother, as absolutely as her limbs are part of her. There is no break of continuity between offspring and parent—the river of life is a continuous stream. We judge of our own identity by the continuity which we see and appreciate; but that greater continuity reaching backwards beyond the womb to the origin of life itself is no less a fact which should be constantly kept in view. The individual, in reality, never dies; for the lamp of life never goes out.

For a full exposition of this problem, Mr. Butler's "Life and Habit" must be consulted, where the reader will find it treated in a masterly way.

This point was very early appreciated in our work; and in a paper read before the Anthropological Institute [4] in the year 1879, but not published, this continuity was insisted upon by means of diagrams, both of animal and plant life, and its connection with heredity was clearly shown, though its relation to memory was only dimly seen. From this paper the following passage may be quoted: "If, as I believe, the origin of form and decoration is due to a process similar to the visualising of object-thoughts in the human mind, the power of this visualising must commence with the life of the being. It would seem that this power may be best understood by a correct insight into biological development. It has always excited wonder that a child, a separate individual, should inherit and reproduce the characters of its parents, and, indeed, of its ancestors; and the tendency of modern scientific writing is often to make this obscure subject still darker. But if we remember that the great law of all living matter is, that the child is not a separate individual, but a part of the living body of the parent, up to a certain date, when it assumes a separate existence, then we can comprehend how living beings inherit ancestral characters, for they are parts of one continuous series in which not a single break has existed or can ever take place. Just as the wave-form over a pebble in a stream remains constant, though the particles of water which compose it are ever changing, so the wave-form of life, which is heredity, remains constant, though the bodies which exhibit it are continually changing. The retrospection of heredity and memory, and the prospection of thought, are well shown in Mrs. Meritt's beautiful diagram."

This passage illustrates how parallel our thoughts were to Mr. Butler's, whose work we did not then know. What we did not see at the time was, that the power of thinking or memory might antedate birth. It is quite impossible adequately to express our sense of admiration of Mr. Butler's work.

Granting then the physical identity of offspring and parent, the doctrine of heredity becomes plain. The child becomes like the parent, because it is placed in almost identical circumstances to those of its parent, and is indeed part of that parent. If memory be possessed by all living matter, and this is what we now believe, we can clearly see how heredity acts. The embryo develops into a man like its parent, because human embryos have gone through this process many times—till they are unconscious of the action, they know how to proceed so thoroughly.

Darwin, after deeply pondering over the phenomena of growth, repair of waste and injury, heredity and kindred matters, advanced what he wisely called a provisional hypothesis—pangenesis.

"I have been led," he remarks, "or, rather, forced, to form a view which to a certain extent, connects these facts by a tangible method. Everyone would wish to explain to himself even in an imperfect manner, how it is possible for a character possessed by some remote ancestor suddenly to reappear in the offspring; how the effects of increased or decreased use of a limb can be transmitted to the child; how the male sexual element can act, not solely on the ovules, but occasionally on the mother form; how a hybrid can be produced by the union of the cellular tissue of two plants independently of the organs of generation; how a limb can be reproduced on the exact line of amputation, with neither too much nor too little added; how the same organism may be produced by such widely different processes as budding and true seminal generation; and, lastly, how of two allied forms, one passes in the course of its development through the most complex metamorphoses, and the other does not do so, though when mature both are alike in every detail of structure. I am aware that my view is merely a provisional hypothesis or speculation; but until a better one be advanced, it will serve to bring together a multitude of facts which are at present left disconnected by any efficient cause." [5]

After showing in detail that the body is made up of an infinite number of units, each of which is a centre of more or less independent action, he proceeds as follows:—

"It is universally admitted that the cells or units of the body increase by self-division or proliferation, retaining the same nature, and that they ultimately become converted into the various tissues of the substances of the body. But besides this means of increase I assume that the units throw off minute granules, which are dispersed throughout the whole system; that these, when supplied with proper nutriment, multiply by self-division, and are ultimately developed into units like those from which they were originally derived. These granules may be called gemmules. They are collected from all parts of the system to constitute the sexual elements, and their development in the next generations forms a new being; but they are likewise capable of transmission in a dormant state to future generations, and may then be developed. Their development depends on their union with other partially developed or nascent cells, which precede them in the regular course of growth. … Gemmules are supposed to be thrown off by every unit; not only during the adult state, but during each stage of development of every organ; but not necessarily during the continued existence of the same unit. Lastly, I assume that the gemmules in their dormant state have a mutual affinity for each other, leading to their aggregation into buds, or into the sexual elements. Hence, it is not the reproductive organs or buds which generate new organisms, but the units of which each individual is composed." [6]

Now, suppose that instead of these hypothetic gemmules we endow the units with memory in ever so slight a degree, how simple the explanation of all these facts becomes! What an unit has learned to do under given conditions it can do again under like circumstances. Memory does pass from one unit to another, or we could not remember anything as men that happened in childhood, for we are not physically composed of the same materials. It is not at all necessary that an unit should remember it remembers any more than we in reading are conscious of the efforts we underwent in learning our letters. Few of us can remember learning to walk, and none of us recollect learning to talk. Yet surely the fact that we do read, and walk, and talk, proves that we have not forgotten how.

Bearing in mind, then, the fundamental laws that the offspring is one in continuity with its parents, and that memory arises chiefly from repetition in a definite order (for we cannot readily reverse the process—we cannot sing the National Anthem backwards), it is easy to see how the oft-performed actions of an individual become its unconscious habits, and these by inheritance become the instincts and unconscious actions of the species. Experience and memory are thus the key-note to the origin of species.

Granting that all living matter possesses memory, we must admit that all actions are at first conscious in a certain degree, and in the "sense of need" we have the great stimulation to action.

In Natural Selection, as expounded by Mr. Darwin, there is no principle by which small variations can be accumulated. Take any form, and let it vary in all directions. We may represent the original form by a spot, and the variations by a ring of dots. Each one of these dots may vary in all directions, and so other rings of dots must be made, and so on, the result not being development along a certain line, but an infinity of interlacing curves. The tree of life is not like this. It branches ever outwards and onwards. The eyes of the Argus pheasant and peacock have been formed by the accumulation, through long generations, of more and more perfect forms; the mechanism of the eye and hand has arisen by the gradual accumulation of more and more perfect forms, and these processes have been continued along definite lines.

If we grant memory we eliminate this hap-hazard natural selection. We see how a being that has once begun to perform a certain action will soon perform it automatically, and when its habits are confirmed its descendants will more readily work in this direction than any other, and so specialisation may arise.

To take the cases of protective resemblance and mimicry. Darwin and Wallace have to start with a form something like the body mimicked, without giving any idea as to how that resemblance could arise. But with this key of memory we can open nature's treasure house much more fully. Look, for instance, at nocturnal insects; and one need not go further than the beetles (Blatta) in the kitchen, to see that they have a sense of need, and use it. Suddenly turn up the gas, and see the hurried scamper of the alarmed crowd. They are perfectly aware that danger is at hand. Equally well do they feel that safety lies in concealment; and while all the foraging party on the white floor are scuttling away into dark corners, the fortunate dweller on the hearth stands motionless beneath the shadow of the fire-irons; a picture of keen, intense excitement, with antennæ quivering with alertness. On the clean floor a careless girl has dropped a piece of flat coal, and on it beetles stand rigidly. They are as conscious as we are that the shadow, and the colour of the coal afford concealment, and we cannot doubt that they have become black from their sense of the protection they thus enjoy. They do not say, as Tom, the Water Baby, says, "I must be clean," but they know they must be black, and black they are.

There is, then, clearly an effort to assimilate in hue to their surroundings, and the whole question is comparatively clear.

Mr. Wallace, in commenting upon the butterfly (Papilio nireus)—which, at the Cape, in its chrysalis state, copies the bright hues of the vegetation upon which it passes its dormant phase—says that this is a kind of natural colour photography; thus reducing the action to a mere physical one. We might as well say the dun coat of the sportsman among the brown heather was acquired mechanically. Moreover, Wallace distinctly shows that when the larvæ are made to pupate on unnatural colours, like sky-blue or vermilion, the pupæ do not mimic the colour. There is no reason why "natural photography" should not copy this as well as the greens, and browns, and yellows. But how easy the explanation becomes when memory, the sense of need, and Butler's little "dose of reason," are admitted! For ages the butterfly has been acquainted with greens, and browns, and yellows, they are every day experiences; but it has no acquaintance with aniline dyes, and therefore cannot copy them.

The moral of all this is that things become easy by repetition; that without experience nothing can be done well, and that the course of development is always in one direction, because the memory of the road traversed is not forgotten.