Popular Science Monthly/Volume 15/July 1879/Pleased with a Feather
| "PLEASED WITH A FEATHER." |
By Professor GRANT ALLEN.
A MURKY London winter afternoon is not exactly a good opportunity for the pursuit of natural history. The snow lies thick on the pavement outside, half melted into muddy slush; while the fog penetrates through the cracks in the woodwork, and the sun struggles feebly athwart the thick yellow sheet which shuts off his rays from the lifeless earth. If I wish to go on a botanical or entomological excursion to-day, I must perforce content myself with a "Voyage autour de ma Chambre." So I rise listlessly from my easy-chair; perambulate the drawing-room in a sulky mood; peer at the Japanese fans on the mantel-shelf; rearrange for the twentieth time those queer little pipkins we brought on our last vacation ramble from Morlaix; pull about my wife's old Chelsea in a savage fit of tidiness; and finally relapse upon the sofa with a fixed determination to be inconsolably miserable for the rest of the day. Evidently I am suffering from that mysterious British epidemic, the spleen, and I may be shortly expected to plunge incontinently over Waterloo Bridge.
Meanwhile, I find a momentary solace in the Indian cushion which lies under my head. A feather is just pushing its sharper end through the morocco-leather groundwork, between those gorgeous masses of gold, silver, and crimson embroidery; which feather I forthwith begin to egg out, by dexterous side pressure, with admirable industry, worthy of a better cause. My wife, looking up from her crewels, mutters something inarticulate about some one who finds some mischief still for idle hands to do; but her obdurate husband pretends inattention, and finally succeeds in catching the feather-end between his finger and thumb. Now that I have successfully pulled it out, I begin to examine it closely, and bethink myself of how, in brighter summer weather, I dissected a daisy for the benefit of such among the readers of the "Cornhill Magazine" as honored me with their kind attention. I shall take a closer look at this feather, and see if it, too, may not serve as a text for a humble lay-sermon concerning the nature and development of feathers in general, and the birds or human beings who wear them.
For the interesting point about a feather is really this, that it grew. It was not made in a moment, like a bullet poured red-hot into a mold: its little airy plumes, branched like a fern into tiny waving filaments, were developed by slow steps, piece after piece, and spikelet after spikelet. And what is true of this particular bit of down which I hold in my fingers, trembling like gossamer at every breath and every pulse, is also true of plumage as a whole in the history of animal evolution. To my mind that great fact, that everything has grown, throws a fresh and wonderful interest into every little object which we can pick up about our fields or our houses. The old view of creation, which represented it as single and instantaneous, made each creature or each organ seem like a mere piece of molded mechanism, with no history, no puzzle, and no recognizable relation to its like elsewhere. But the new view, which represents creation as continuous, progressive, and regular, teaches lis to see in every species or every structure a result of previous causes, an adaptation to preexisting needs. Thus we are enabled to find in a flower, a fruit, or a feather, innumerable clews which lead us back to its ultimate origin, and give delightful exercise to our intelligence in tracing out the probable steps by which this complex whole has been produced.
I often figure to myself the difference between the two ways of regarding natural objects, by means of the initial letters in an ordinary volume, and the initial letters which Mr. Linley Sambourne draws for us so cleverly in "Punch." Look at the big O of a newspaper leader—it is just a mass of metal, poured into a circular or oval type. But look at the big O which the ingenious artist tricks out for us with social allusions or political innuendoes, and what a world of amusement you will find if you take the trouble to spell out all its quaint devices! See how every curl has some playful hit at a noble lord or an honorable member; how every detail smiles with gentle satire at some passing event or some universal topic. Not a touch but has a meaning for those who will seek it; not a careless little smudge in the corner but brims over with deep purpose and infinite wealth of covert mirth. So it is, I think, with flowers, fruits, or feathers, when once we have learned to look for their hidden hints. This little twist points back to some strange fact in the past history of the species; that unobtrusive spur or knob is the clew to whole volumes of botanical or zoological lore. Not a detail but tells of the origin and development of the whole; not a tuft, a spot, or a streak but teems with information for the seeker who has found out the method of seeking aright.
Again, to vary our simile, let us visit some ancient British earthwork or Roman camp. If we go as mere rustics, we see in it all nothing more than a broken ridge of earth on the summit of a rolling down. We are not even sure whether it is really the handiwork of man, or some queer natural formation like the Devil's Dike, the Giant's Causeway, and the parallel roads of Glen Roy. But if we go under the guidance of some skilled archaeologist, what a flood of light he is able to throw over its history and its meaning! This row of strongholds, he tells us, formed the frontier line, say between the Welsh of Dorset and the Welsh of Devon. Here the Durotriges and Damnonii, the men of the water-vale and the men of the hills, faced one another from their opposite heights. Sweep round your eye in a semicircle along this series of points, overhanging the valley of the Axe, and you will find every higher summit crowned with a "castle," a rude earthwork raised by the men whom our fathers drove out of the land. That was their Balkan or Suleiman line, their cordon of border forts, their row of beacons to announce the approach of the hostile hill-men on the war-trail against their homes. Then our antiquary would turn to the work itself, and would point out the various parts, the mode of defense, the simple tactics of those primitive Vaubans. Or else he would show us the Roman detail of the later encampment; the square scar that marked the prætorian quarters; the regular succession of gates and defenses. All this he would tell us from the bare inspection of the existing remains, reconstructing the lost history from his stored-up knowledge of like instances elsewhere.
But I am wandering sadly from my London room and my little feather, this wintry afternoon. Let me look at it once more, and try to realize, in like manner, the story involved in its downy vans.
In the first place, this feather, as an anatomist would tell us, is "a dermal modification"—in other words, an altered bit of the skin. Every part of a plant or animal undergoes changes, our modern teachers say, just in accordance with the external influences which affect it. But the skin of an animal is naturally exposed to many more such surrounding agencies than its internal organs. Accordingly, we find that no structure exhibits such strange variations as the skin. Besides the regular modifications which we see in the scales or horny plates of fishes, the smooth coats or solid shells of reptiles, the feathers of birds, and the hair of mammals, numerous other minor peculiarities occur in almost every species. Such are the horns of cows and goats, the spike of the rhinoceros, the beaks, nails, claws, hoofs, and talons of beasts or birds, and the tail-plumes, ruffs, lappets, crests, and ornamental adjuncts of all the more aesthetic animals. In no class are these variations in the external covering more conspicuous than among the biped tribe whose spoils I am now holding in my hand as the text for our afternoon's discourse.
How birds first came to be winged and feathered we can hardly say as yet. To be sure, most of us have seen a picture, at least, of that strange oolitic monster, the pterodactyl, a saurian with a head like a crow, but having the fore-part protracted into long jaws, fitted with teeth not very dissimilar from those of a crocodile; while its legs were supplied, apparently, with a membrane, by whose aid the creature probably flew about in the same manner as a bat. These real flying dragons recall in many points the appearance of a bird, especially in the skull and the position of the eyes. Moreover, Professors Marsh and Huxley have shown that the earliest fossil birds resemble the pterodactyl and other reptiles in many important peculiarities of structure, far more than their modern representatives. Some of them even possess teeth set in their jaws after a reptilian fashion. Though the evidence still remains very fragmentary, we may regard it as probable that birds are descended from some early reptilian form, more or less like the peterodactyl, if not actually from that partially-winged saurian itself. But perhaps it is premature to build with any confidence upon such dubious ground; and we may consequently accept the earliest birds on their own responsibility, without inquiring too curiously into their antecedents, or compelling them to produce a genealogical table of their ancestry.
The essential characteristic of a bird consists in the fact that it is a flying animal; and feathers are the kind of skin-covering best adapted to its special manner of life. In their nature and mode of development, feathers closely agree with the hair of mammals; but the differences between them are all of a sort which fit the bird for its aërial existence. We see this fact very clearly if we look at the instance of those birds which do not fly. Running species, such as the ostriches, have downy plumes, in which many of the essential characters of the feather are greatly obscured. In the emu, whose habits are more strictly cursorial, the plumage almost resembles hair. In the cassowary the likeness becomes yet more striking, while the wingless apteryx of New Zealand has not even the few bare quills which stand for wing-feathers in the former bird. So, too, among those sedentary marine birds, the penguins, where the wings have been converted into a sort of fins for diving, the feathers undergo a parallel change into scales. There is reason, indeed, to suspect, as Mr. Lowne has pointed out, that these marine species retain in many ways the primitive characters of the class; and we may perhaps regard them rather as birds in whom the pinions and plumage have never fully developed than as birds in whom they have assumed a new form.
On the other hand, the truest feathers—that is to say, those which exhibit the essential features of a feather in the most marked manner—are specially connected with the act of flight. The general surface of the body is covered with soft down, among which sprout the delicate plumes that form the common covering for warmth and protection; but only on the wings and tail do those long and stiff quills appear which, after all, are the feathers par excellence, the models and prototypes of all the rest. Now, it is quite obvious to every one that the wings are the organs of flight, and that the quills are the part by means of which the powerful muscles of the bird are brought to bear upon the sustaining atmosphere. As for the tail, its functions resemble those of a rudder, in directing the course of flight to right or left. The difference between these true flying feathers and the mere clothing of the back and breast is so striking that naturalists have given them separate technical names, as quills and plumes respectively.
From such facts, and others like them, I think we may arrive at an important conclusion—that feathers have been developed and selected through the habit of flight. Probably our monstrous friend the pterodactyl had only a membranous wing or bit of skin, extending from the elongated outer finger of his forearm to the leg. Such a parachute we still see among the so-called flying-squirrels and lemurs; while in the bats it has developed into a sort of webbed wing. But if any of the early birds happened to possess an altered hair-like or scale-like covering—the relic, perhaps, of some common reptilio-mammalian ancestor—which afforded them any extra grip upon the air through which they fell rather than floated, then those individuals would thereby gain an extra chance of catching prey or escaping enemies, and therefore of survival in the constant rivalry of species with species. The more perfect these organs became, the more closely adapted to the function of flight, the greater the advantage the bird would derive from their possession, and therefore the better the chance of survival which it would obtain. Thus, apparently, the most aërial birds have the largest and strongest quills, and the most quill-like plumes, while the running and diving birds have either never developed these adjuncts in their highest form, or else have lost them by disuse.
Let me take down one of the peacock's feathers, which stands on the mantelpiece in this Vallauris vase, and closely examine its structure. It consists of a long central shaft, horny and tubular at the lower end, and filled above with a soft, white, spongy matter; while a number of little barbed branches are given off on either side, curiously interlaced by means of tiny hooked filaments, whose myriad threads are far too numerous for the most industrious critic to count up. Everybody knows that this tubular structure combines in the highest degree the mechanical requisites of lightness and strength; and everybody has read that it is employed with the self-same object by human engineers, in such constructions as the great bridges which span the Menai Straits or the St. Lawrence at Montreal. Evidently this peacock's feather, though now converted to a purely ornamental function, was originally developed for the purpose of flight. If I doubt it for a moment, I need only look at the quill-pen in my desk over yonder. That flat blade, close-textured and strongly woven, clearly belongs to a flying organ; and this beautiful mass of green and golden waving plumelets is evidently modeled on the self-same plan. It is useless, or next to useless, now, for flight; but it still bears clear traces of its original function in the structure and arrangement of its shaft and barbs.
Next, let me look at the little downy feather I have abstracted from the Indian cushion. This is not a flying organ, nor did its representative on any early ancestor ever fulfill a similar office. Light, warm, soft, fluffy, its whole object is decidedly that of clothing against chilly weather, and protection against thorns or other rough bodies. Yet when I examine it closely, I see that the same general ground-plan still runs through it, as that which ran through the goose-quill and the peacock's tail-covert. "How comes this?" I ask myself; "here we have a small, delicate, almost fleshy shaft, instead of the horny quill; and a feeble set of downy barbs instead of the strong, well-woven blade: yet the main features remain unaltered, though the function is entirely different. How can I account for this resemblance?"
The case of the emu and the apteryx helps to throw light upon the problem thus disclosed. Where birds fly very little, their feathers never acquire or else soon lose the distinctive quill-like character; but where birds fly much, the quill-producing tendency becomes strong and pronounced. Primarily, this tendency ought to affect only those parts which are used in flight, namely, the wings and tail; and, as a matter of fact, we have seen that these are the parts which exhibit it in the highest degree. It would be almost impossible, however, that a change of such magnitude should be set up in some of the feathers, without to a lesser extent affecting all the rest. We might as well expect that the hair on a certain patch of some animal's skin would grow thick and spike-like, without any corresponding alteration in the rest of his body. True, natural selection does sometimes produce this result for some special purpose, when it is highly desirable that an acquired character should be confined to a small area. But, as a rule, when one part of the skin hardens, like that of a turtle or crocodile, the tendency to bony development shows itself in every part; and when certain hairs become converted into thick spines, like those of the hedgehog, the echidna, and the porcupine, a general bristly tone pervades almost all the coat. The scaly plates of the armadillo and the pangolin in like manner communicate a universal scaliness to the whole external surface of the animal. We may say in simple language that the body has got into the habit of producing certain structures, and that the habit extends to analogous parts in which it is not strictly necessary.
This is the case with the flying birds. Some of their feathers—modified scales or hairs—having become specially adapted for flying, all the rest follow suit to a greater or less extent. Indeed, we can hardly imagine how quills could come into existence at all, unless we allow that there must first have been an adventitious tendency toward the production of light-barbed shafts over the whole body. Those birds which exhibited this adventitious habit in the highest degree would become the ancestors of the aërial species, in whom it is still further developed by natural selection; while those birds which exhibited it in the least degree would become the ancestors of the diving, running, and scraping tribes, in whom natural selection favors rather such special adaptations as web-feet, fin-like wings, long and powerful legs, and ornamental plumage.[1]
The æsthetic philosopher, however (if the reader will permit me to designate myself by such a periphrasis), is far more interested in the modifications which feathers undergo, after they have become feathers, than in those which they undergo before reaching that stage of their development. For the infinite variety of coloring, the exquisite tones of metallic sheen, the graceful arrangements of crests, tufts, plumes, and lappets, which render birds such conspicuous objects in our museums or gardens, are all of them due to the pigments or shapes of feathers, and all of them have apparently been produced by the voluntary choice of beautiful mates among the birds themselves.
The modifications of feathers thus originated form, of course, a clew to the tastes of the various birds which possess them; because each species will naturally select such mates as best satisfy its ideas of the beautiful, and so will transmit the admired qualities to its descendants. It is a remarkable fact that the tastes of many birds, indirectly disclosed in such a manner, coincide very closely with the tastes of mankind at large.
Not all birds, however, exhibit equally these æsthetic preferences. Some large families, like those of the hawks, eagles, owls, and nightjars, are noticeable neither for beauty of color nor for richness of song. Other classes, again, like those of our own English hedge-birds, seem rather musical than chromatically inclined in their tastes. As a rule, we may say that birds of prey and nocturnal birds are very deficient in aesthetic feeling, all their energies being apparently directed to swiftness of pursuit and skill in hunting; while, on the other hand, small seed-eating birds, and those which live on little insects or other minute animals, generally expend all their æsthetic sentiment on the faculty of song. But only those birds which live upon fruits, or the mixed nectar and insects extracted from flowers, usually possess brilliant colors.
I have already more than once pointed out to the readers of the "Cornhill Magazine" the probable reason for this peculiar connection.[2] The eyes of fruit-eating or flower-feeding animals become specially adapted to the stimulation of colored light, and therefore the creatures become capable of receiving special pleasure from such sources. Accordingly, those among their fellows which displayed brilliant colors would prove most attractive, and would be chosen as mates for their beauty. I have instanced before, among the flower-feeding species, the numberless varieties of humming-birds, and the almost equal profusion of sun-birds, to which we may add a few other minor forms, such as the brush-tongued lories; while among the fruit-eaters, the parrots, macaws, cockatoos, toucans, barbets, nutmeg-pigeons, fruit-pigeons, chatterers, and birds-of-paradise, may stand as cases in point. But it will be more interesting here to glance briefly at the various modes in which these colors are produced than to extend the list of species which display them. The commonest method of exhibiting color is by means of pigments either in the external coating of the feathers or in their deeper layers. Cases of this sort are too frequent to need special exemplification; but some birds have brilliant hues otherwise displayed, as in the wattles of the common barn-door fowl, the fleshy appendages of the turkey, and the painted face of the carrier-pigeon. The wattled honey-sucker of Australia has two drooping folds of flesh which fall like bonnet-strings under his throat; the king-vulture has his head and neck covered with naked skin of every hue in the rainbow; and the cassowary (by far the most frugivorous of all the ostrich tribe) has the same parts of a brilliant red, variegated with melting shades of blue. In many other birds the beak becomes an ornamental adjunct; and this tendency reaches its furthest development in the bill of the toucan, whose colors almost vie with the humming-bird itself. But the most curious of all such aesthetic modifications is that from which the wax-wings derive their name. In these birds the shafts of certain wing-feathers are prolonged into small, horny expansions, bright scarlet in hue, exactly resembling, both in color and texture, little tags of red sealing-wax.
The metallic luster of feathers is generally due to fine lines on the surface of the barbules, like those which produce the iridescence of mother-of-pearl. Such luster occurs in the sun-birds and hummingbirds, and on many other less ornamented species. Sometimes gleaming like gold or bronze, sometimes fading away into jetty black, anon reappearing as glancing outbursts of crimson, azure, or exquisite green, it has gained for the birds on which it appears such poetical names as ruby-throated, topaz-crested, amethystine, golden, emerald, and sapphire. Not only does it occur upon the burnished neck of the dove, but it gives a passing splendor to the sable livery of the crow, and throws a thousand changeful hues over the glossy plumage of the mallard.
But besides the ornamental effects of color and luster, feathers appeal to the æsthetic taste of birds by their form, their arrangement, and their variety. Only the plainest birds have all their plumage exactly uniform and simply disposed. In an immense number of species certain feathers have been specially modified in shape so as to form crests, fan-like tails, lappets, and other ornaments. And just as a good architect lavishes his decorations chiefly on the constructive points of his building, the critical parts, such as arches, doorways, windows, and architraves, so do we find that birds have chosen to place their decorative modifications on the most important nodal points of their bodies, and that they generally lavish their richest coloring upon these ornamental adjuncts. This peacock's feather, for instance, formed part of a gorgeous semicircular fan, which composed, as it were, the background or reredos of the whole living picture when expanded, and the train of the majestic sultan when folded in repose. A plume from the neck or back, though still beautiful with golden green and faintly purplish blue, would not have exhibited those splendid eye-like spots which reflect the sunlight in a mingled mass of glory from this perfect tail-covert. Only in the most fitting positions for decoration do birds, as a rule, expend their choicest designs.[3]
The feathers of the ostrich naturally occur first to the human investigator of æsthetic taste in birds. The quills of the wing and tail, here purely ornamental in their function, compose the well-known silky plumes of commerce. The common crane has also beautiful elongated wing-feathers, which fall on either side of the tail in graceful waving masses. If we may trust the doubtful pictures which have come down to us, that grotesque and gigantic pigeon, the dodo, possessed similar tufts of ornamental plumage. But the great order of gallinaceous birds, or the hen and turkey tribe, display the most magnificent tails of all, so familiarly known in the peacock and the pheasant family, as well as in the humbler denizens of our English farmyards.
Crests form another favorite ornamental device among birds, occurring independently in the most different orders. The graceful tuft of the gray heron must have attracted the attention of every observer. Among the pheasants similar decorative adjuncts are common; and the curassow shows this peculiarity in a very beautiful form. With parrots and cockatoos, crests are of frequent occurrence, and they make equally striking features among the humming-birds and sun-birds. Indeed, it may be roughly asserted that those birds which seek their food among flowers and fruits, and which consequently exhibit a taste for bright colors, are also the species in which ornamental tufts of feathers most frequently occur. But crests are also found even among the generally somber and inartistic birds of prey, being by no means unusual in the owls and hawks, while the serpent-eating secretary-bird derives his queer name from the fancied resemblance of his top-knot to a pen stuck behind the ear. Other well-known instances of crested species are the hoopoe, the wax-wing, the golden-crested wren, and many jays. But the umbrella-bird, a Brazilian fruit-crow, exhibits the fullest development of this particular ornament, having the whole head covered by a dome of slender, shining blue feathers, about five inches in length by four and a half in breadth. It may be added that almost all birds which possess these ornaments possess also the power of raising or depressing them at will; and that during the season of courtship the male birds constantly expand all their charms before the eyes of their admiring mates. We have all seen this ostentatious display ourselves in the case of the peacock, the turkey, and the barn-door fowl. It proves almost beyond a doubt the aesthetic purpose and function of such otherwise useless, inconvenient, arid vitally expensive excrescences.
Sometimes the crest is produced by some other means than that of a mass of plumes. Besides the well-known fleshy comb of our friend chanticleer, there is the horny helmet of our old acquaintance the cassowary, and the quaint protuberances on the beak of the jacana. Most eccentric of all is the device adopted by the hornbills, whose name sufficiently indicates their peculiarity in this respect. The beak in these birds is prolonged above into a single unicorn-like process, extravagantly disproportioned to the general size of its wearer.
On the other hand, it may be noted that most small singing-birds, or other species which live on seeds, grains, insects, and mixed small food, are destitute of tufted ornaments, as well as of brilliant coloring.
The lappets, frills, or other neck-pieces of so many decorated species must not pass entirely unnoticed in this review of æsthetic devices among birds. Beginning with the mere burnished breast-plumage of the pigeon, or the crimson stomacher of the robin, they become at last, in the humming-birds, sun-birds, and other tropical species, the most exquisite drapery of amethyst, topaz, emerald, or golden bronze. The so-called beard of the turkey is a special example of a very aberrant type. The ruff derives his English name from a similar peculiarity.
The birds-of-paradise unite all these modes of ornamentation in the highest degree, and with the most harmonious results. They join the graceful plumes of the ostrich to the dainty coloring of the sun-bird. Crests almost as largely developed as that of the umbrella-bird overshadow their beautiful heads; frills as full as those of the hummingbirds fall down in metallic splendor before their gorgeous necks. And, if any proof be wanting of the connection between the nature-of the food and the general beauty of the plumage, it may be found in the fact that these royally-attired creatures are first cousins of our own dingy crows and jackdaws; but, while the crow seeks his livelihood among the insects and carrion of an English plowed field, the bird-of-paradise regales his lordly palate on the crimson and purple fruits which gleam out amid the embowering foliage of Malayan forests.
Equally magnificent are the members of the genus Epimachus, inhabitants of the same brilliant archipelago. Their long, silky plumes float behind them in the same graceful curves; their burnished necks are adorned with the same glancing hues of ruby and emerald. Yet they are surpassed in one respect by their distant relatives, the lyrebirds, first cousins of our diminutive English wrens. Though destitute of brilliant coloring and metallic sheen, these curious birds exhibit in their long and beautiful tails the only undoubted example among the lower animals of a love for symmetrical patterns.
I have only bethought me now of a few among the countless modifications which feathers undergo, for the aesthetic gratification of their wearers, or rather of their wearers' mates, and the list might be almost indefinitely prolonged. But it will he better worth while, perhaps, to glance briefly at another set of facts connected with feathers—I mean their artificial employment by human beings for the exactly identical purpose of aesthetic decoration. Could any fact show more clearly the similarity of artistic feeling which runs through the whole animal series than this thought, that man makes use, for his own adornment, of the very self-same beautiful colored baubles which the birds originally developed to charm the eyes of their fastidious brides?
I need not recall by name the various kinds of plumage so employed—the feathers of the ostrich, the marabou, the bird-of-paradise, the emu, the pheasant, and the gull; the sun-birds and the hummingbirds mercilessly slaughtered by the million in the Malay Archipelago, Ceylon, and Trinidad to supply the bonnets of London and Paris; the swan's-down, the grebe, the widow-birds, the cockatoos, the parrots, the macaws, which decorate our wives and children with barbaric spoils. It will suffice to remember, in passing, that from the feather mantles of Hawaian kings, the feather kirtles of American Indians, and the feather mosaics of Mexico, to the plumes of our own court-dress, our own military uniforms, and our own quaintly surviving funeral processions, these same "dermal modifications" of birds have served an aesthetic purpose, better or worse, throughout the whole course of human history.
Nor does the resemblance stop here. Mankind employs tufts of feathers for decorative display in just the same manner as the birds who originally developed them. The Red Indian in his war-paint dressed out his head with a row of quills, arranged in exactly the same order as the top-knot of a hoopoe or a cockatoo. The feather collars of so many savage tribes recall to the letter the frills and lappets of the humming-bird or the epimachus. The ostrich-plumes of our English royal receptions, and the panache of our European officers' dress, are adaptations from the primitive idea of the crane and the umbrella-bird. Everywhere, the tuft of feathers is placed on some prominent part of the person—some "constructive point" in the human or avian system of architecture.
A ring at the bell warns me that a visitor is standing at the door. I throw my little feather hastily into the fire, and cut short my reflections to welcome my expected guest. But one last thought occurs to me before I close my afternoon's meditation. To be "pleased with a feather" appeared to the great metaphysical poet of the eighteenth century a mark of childish simplicity. Perhaps it may be so; but, after all, is there not some solace in that new philosophy which can enable one to pass a whole hour, this murky afternoon, in pleasurable contemplation of that tiny plume which seems no contemptible subject of human study to Charles Darwin and Herbert Spencer?—Cornhill.
- ↑ Of course no effect, in nature is really accidental, that is to say, uncaused; but, in organic nature, effects which arise from special collocations of causes, unconnected with the previous habits of a plant or animal, may fairly be called adventitious. If they result in some alteration beneficial to the species, the alteration will be further strengthened by natural selection, and its final outcome will be a purposive structure—that is to say, a structure specially adapted to its peculiar function. But it must be remembered that almost all purposive structures were in their origin adventitious. I say "almost all" and not "all," because an exception must be made in favor of what Mr. Herbert Spencer calls "functionally-produced structures."
- ↑ See a paper on "The Origin of Flowers," in "The Popular Science Monthly Supplement" for June, 1878; and another on "The Origin of Fruits," in "The Popular Science Monthly" for September, 1878.
- ↑ I say "as a rule," because the hornbills, toucans, vultures, certain pigeons, and a few other species, offend against our ordinary human canons of taste; but the ornaments of birds seldom or never render them ridiculous in our eyes, like those of many highly decorated monkeys.