"The tiny moss, whose silken verdure clothesThe time-worn rock, and whose bright capsules rise,Like fairy urns, on stalks of golden sheen,Demand our admiration and our praise,As much as cedar kissing the blue skyOr Krubul's giant-flower. God made them all,And whatHedeigns to make should ne'er be deem'dUnworthy of our study."
"The tiny moss, whose silken verdure clothesThe time-worn rock, and whose bright capsules rise,Like fairy urns, on stalks of golden sheen,Demand our admiration and our praise,As much as cedar kissing the blue skyOr Krubul's giant-flower. God made them all,And whatHedeigns to make should ne'er be deem'dUnworthy of our study."
Exquisite too are the Ferns, in their arching fronds, so richly cut in elegant tracery. See a fine crown of the Lady Fern in a shaded Devonshire lane, and confess that grace and beauty are triumphant there. And in the saturated atmosphere of the tropical islands, where these lovely plants form a very large proportion of the entire vegetation, and some of them rise on slender stems thirty or forty feet in altitude, from the summit of which the wide-spreading fronds arch gracefully on every side, like a vast umbrella of twinkling verdure, through whose filagree work the sunbeams are sparkling,—what can be more charming than Ferns?
The queenly Palms, too, are models of stately beauty. Linnæus called themvegetabilium principes; and, when we see them in some noble conservatory of adequate dimensions, such as the glass palm-house at Kew, crowded side by side, with their crowned heads, and lofty stature, and proud, erect bearing, we are involuntarily reminded of the monarchs of many kingdoms met in august conclave.
"Lo! higher still the stately palm-trees rise,Chequering the clouds with their unbending stems,And o'er the clouds, amid the dark-blue skies,Lifting their rich unfading diadems.How calm and placidly they restUpon the heaven's indulgent breast,As if their branches never breeze had known!Light bathes them aye in glancing showers,And Silence, 'mid their lofty bowers,Sits on her moveless throne."
"Lo! higher still the stately palm-trees rise,Chequering the clouds with their unbending stems,And o'er the clouds, amid the dark-blue skies,Lifting their rich unfading diadems.How calm and placidly they restUpon the heaven's indulgent breast,As if their branches never breeze had known!Light bathes them aye in glancing showers,And Silence, 'mid their lofty bowers,Sits on her moveless throne."
Are the Grasses worthy of mention for their beauty? Surely, yes. Many of them display a downy lightness exquisitely lovely, as the common Feather-grass. The golden panicles of the great Quake-grass, so curiously compacted and hanging in stalks of so hair-like a tenuity as to nod and tremble with the slightest motion, how beautiful are these! And the satiny plumes of the Pampas-grass projecting from the clump of leaves form a fine object. But the Bamboos, those great arborescent Grasses of the tropics, form a characteristic feature of the vegetation of those regions, of almost unexampled magnificence. I have seen them in their glory, and can sympathise with the philosophical Humboldt in the powerful effect which the grandeur of the Bamboo produces on the poetic mind. It is an object never to be forgotten, especially when growing in those isolated clumps, that look like tufts of ostrich-plumes magnified to colossal dimensions. A thousand of these noble reeds standing in close array, each four or five inches in the diameter of its stem, and rising in erect dignity to the height of forty feet, and all waving their tufted summits in diverging curves moved by every breeze,—form, indeed, a magnificent spectacle. Growing in the most rocky situations, the Bamboo isfrequently planted in Jamaica on the very apex of those conical hills which form so remarkable a feature in the landscape of the interior, and to which its noble tufts constitute a most becoming crown.
Mr Ellis thus describes the elegance of these magnificent Grasses in Madagascar:—
"The base of the hills and the valleys were covered with the Bamboo, which was far more abundant than during any former part of the journey. There were at least four distinct varieties: one a large growing kind, erect nearly to the point; a second smaller, seldom rising much above twenty feet in height, bushy at the base, and gracefully bending down its tapering point. A third kind rose in single cane, almost without a leaf, to the height of thirty feet or more; or, bending over, formed a perfectly circular arch. I also saw a Bamboo growing as a creeper, with small short joints, feathered with slender leafy branches at every joint, and stretching in festoons from tree to tree along the side of the road, or hanging suspended in single lines from a projecting branch, and swinging gently with the passing breeze. The appearance of the Bamboo when growing is exceedingly graceful. Sometimes the canes, as thick as a man's arm at the base, rise forty or fifty feet high, fringed at the joints, which are two or three feet apart, with short branches of long, lance-shaped leaves. The smaller kinds, which abound most in this region, are still more elegant; and the waving of the canes, with their attenuated but feathery-looking points, bending down like a plume, and the tremulous quivering,even in the slightest breeze, of their long, slender leaves, present ever-varying aspects of beauty; and, combined with the bright-green colour of the Bamboo-cane and leaf, impart an indescribable charm to the entire landscape."[217]
Glorious in loveliness are theMusaceæ, the Plantains and Bananas of the hot regions. Humboldt calls the Banana "one of the noblest and most lovely of vegetable productions;" and truly its enormous, flag-like leaves of the richest green, permeated by nervures running transversely in exactly parallel lines, and arching out in every direction from the succulent, spongy, sheathed stem, command our admiration, apart from the beauty of their flowers, or the importance of their fruit.
In a description of a mountain scene in Tahiti, drawn with graphic power by Charles Darwin, the Banana forms a prominent element:—"I could not look on the surrounding plants without admiration. On every side were forests of Banana; the fruit of which, though serving for food in various ways, lay in heaps decaying on the ground.... As the evening drew to a close, I strolled beneath the gloomy shade of the Bananas up the course of the stream. My walk was soon brought to a close, by coming to a waterfall between two and three hundred feet high; and again above this there was another.... In the little recess where the water fell, it did not appear that a breath of wind had ever blown. The thin edges of the great leaves of the Banana, damp with spray, were unbroken, instead of being, as is so generally the case, split into athousand shreds. From our position, almost suspended on the mountain-side, there were glimpses into the depths of the neighbouring valleys: and the lofty points of the central mountains, towering up within sixty degrees of the zenith, hid half the evening sky. Thus seated, it was a sublime spectacle to watch the shades of night gradually obscuring the last and highest pinnacles."[218]
This scene must have been one of surpassing sublimity and loveliness. Few doubtless have ever beheld anything that can be compared with it. But perhaps many have felt—I have, often,—that there are occasions in which the sense of the beautiful in nature becomes almost painfully overpowering. I have gazed on some very lovely prospects, bathed perhaps in the last rays of the evening sun, till my soul seemed to struggle with a very peculiar undefinable sensation, as if longing for a power to enjoy, which I was conscious I did not possess, and which found relief only in tears. I have felt conscious that there were elements of enjoyment and admiration there, which went far beyond my capacity of enjoying and admiring; and I have delighted to believe, that, by and by, when, in the millennial kingdom of Jesus, and, still more, in the remoter future, in the dispensation of the fulness of times, the earth—the "newearth,"—shall be endowed with a more than paradisaical glory, there will be given to redeemed man a greatly increased power and capacity for drinking in, and enjoying the augmented loveliness. Doubtless the risen and glorified saints, sitting with theKing of kings upon His throne, will have the senses of their spiritual bodies expanded in capacity beyond what we can now form the slightest conception of; and as all then will be enjoyment of the most exquisite kind, and absolutely unalloyed by interruption or satiety,—the eye will at length be satisfied with seeing, and the ear be satisfied with hearing. "I shall be satisfied, when I awake up with thy likeness."
It is inFlowersthat the beauty of the vegetable world chiefly resides; and I shall now therefore select a few examples from the profusion of lovely objects which the domain proper of Flora presents to us.
That very curious tribe of plants, theOrchideæ, so remarkable for the mimic forms of other things, that its blossoms delight to assume, is also pre-eminent in gorgeous beauty. Take theSobraliæ,—terrestrial species from Central America, where they form extensive thickets, growing thrice the height of man, with slender nodding stems, and alternate willow-like leaves, and terminal racemes loaded with snow-white, pink, crimson, or violet flowers.[219]Imagine the crushing through "thickets" of the lovelyS. macrantha! The large lily-like blossoms of this species are eight inches long, and as many wide, of the richest purple crimson, and of the most elegant shape conceivable, with the lip so wrapped round the column as to appear funnel-shaped, bordered by an exquisitely-cut fringe.
I have before alluded toPhajus Tankervilliæ, that richlily-like spike of blossom which I stumbled on in the midst of a dense thicket in the mountains of Jamaica. Another terrestrial genus of great elegance isCypripedium, of which we have one native species,C. calceolus, the yellow lady's slipper,—one of the most charming, but the rarest and most difficult of propagation, of British plants. But this is far excelled in beauty by many of the exotic species; as, for example, the exquisiteC. barbatumfrom Malacca. The very foliage is princely; for the nervures and cross-veins form a network pattern of dark green upon the light green area of each broad leaf. The blossom rears up its noble head erect, with its standard-petal of white, striped with green and purple, the wing-petals studded with purple tubercles along their edges, and the lip or slipper-shaped petal of a dark purple hue.
My readers may have occasionally noticed a little plant, in the most recherchées stove-houses, of so much delicacy and preciousness that it is invariably kept under a bell-glass. I mean theAnæctochilus setaceus. It belongs to this tribe, and is a terrestrial species, growing about the roots of the trees in the humid forests of Ceylon. Its exquisite loveliness has attracted the attention of even the apathetic Cingalese, who call it by the poetical epithet ofWanna Raja, or king of the forest. It does not appear to possess any peculiar attractiveness in its blossoms,—indeed, I have never seen it in flower; but its leaves, which grow in opposite pairs, are elegantly heart-shaped, of a deep rich greenish-brown hue, approaching to black, of a surface which resembles velvet, reticulated all overwith pale golden veins, which, being numerous and minute, have a very charming appearance, somewhat like the pale network on black patches which we see in the wings of some dragon-flies.
The epiphyte Orchids are also magnificent in beauty. One of the handsomest genera isDendrobium, containing many species, mostly natives of Southern Asia and the great islands. Perhaps the finest of all isD. nobile, of which the sepals and petals are greenish-white, tipped with rich purple, and the downy tube-like lip is of the same regal hue in the interior, with a pale yellow margin.
By the side of this you may set the lovelyHuntleya violacea, one of the discoveries of Sir R. Schomburgk in the interior of Guiana. Its broad wavy petals of the softest richest violet, "vary in intensity from deepest sapphire to the mild iridescence of opal." This fine flower has a melancholy interest from its being associated with the death of Sir Robert's friend and fellow-servant, Mr Reiss. The gorgeous scenes of tropical vegetation in which the plant was found, and the sad accident, are thus depicted by the accomplished traveller:—
"I discovered theHuntleya violaceafor the first time in October 1837, then on my ascent of the river Essequibo. The large cataract, Cumaka Toto, or Silk Cotton Fall, obliged us to unload our corials, and to transport the luggage overland, in order to avoid the dangers which a mass of water, at once so powerful and rapid, and bounded by numerous rocks, might offer to our ascent.While the Indians were thus occupied, I rambled about one of the small islands, which the diverging arms of the river formed in their descent, and the vegetation of which had that peculiar lively appearance which is so characteristic of the vicinity of cataracts, where a humid cloud, the effects of the spray, always hovers around them. Blocks of syenite were heaped together; and while their black shining surface contrasted strongly with the whitish foam of the torrent, and with the curly waves beating against the rocky barriers—as if angry at the boundary which they attempted to set to the incensed element—their dome-shaped summits were adorned with a vegetation at once rich and interesting.Heliconias,Tillandsias,Bromelias,Ferns,Pothos,Cyrtopodiums,Epidendrums,Peperomias, all appeared to struggle for the place which so small a surface afforded to them. The lofty mountains, Akaywanna, Comute, or Taquia, and Tuasinki, recede and form an amphitheatre, affording a highly interesting scene, and no doubt the most picturesque of that part of the river Essequibo.
"I was attracted by a number ofOncidium altissimumwhich covered one of the rocky piles, and astonished me by their long stems and bright colour of their flowers, when my attention was more powerfully attracted by a plant, the appearance of which, although different from the pseudo-bulbous tribe, proclaimed, nevertheless, that it belonged to that interesting family, theOrchideæ. The specimens were numerous; and clothed almost, with their vivid green, the rugged and dark trunks of the gigantictrees, which contributed to the majestic scene around me. It was not long before I discovered one of these plants in flower. It was as singular as it was new to me;—the sepals and petals of a rich purple and velvet-like appearance; the helmet, to which form the column bore the nearest resemblance, of the same colour; the labellum striated with yellow.
"In the sequel of my expeditions, I found it generally in the vicinity of cataracts, where a humid vapour is constantly suspended, and where the rays of the sun are scarcely admitted through a thick canopy of foliage. I traced theHuntleyafrom the sixth parallel of latitude to the shady mountains of the Acaria chain near the equator; but in its fullest splendour it appeared at one of the small islands among the Christmas cataracts in the river Berbice. There is a melancholy circumstance connected with the plant, which its appearance never fails to recall to my memory. Their singular beauty at this spot induced my friend, Mr Reiss, who accompanied me as a volunteer during the unfortunate expedition up the river Berbice, to draw and paint it on the spot. He was yet occupied with this task when the last of our canoes was to descend the dangerous cataract. He arose from his occupation, desirous to descend with the Indians in the canoe, although against my wish, but he persisted. The canoe approached the fall; it upset; and, of thirteen persons who were in it at the time, he was the only one who paid the rash attempt with his life. He is now buried opposite that island, the richest vegetable productions of which it was his last occupation to imitate on paper and in colours."[220]
We might linger long on these flowers of strange loveliness, but space compels us to forsake them and to turn to some other examples in the wide range of Flora's domains. How glorious a sight must be the sheeted Rhododendrons of the Himalaya peaks, on whose lofty elevations Dr Hooker found these fine plants in great prominence, "clothing the mountain-slopes with a deep-green mantle, glowing with bells of brilliant colours; of the eight or ten species growing here, [on the Zemir, in Sikkim, twelve thousand feet above the sea,] every bush was loaded with as great a profusion of blossoms as are their northern congeners in our English gardens!"[221]
The noblest of the genus is that which is dedicated to Lady Dalhousie. It is an epiphyte, being always found growing, like the Orchids, among mosses and ferns, upon the trunks of large trees, especially oaks and magnolias, at an elevation of from seven to ten thousand feet. In this particular, in the fragrance of its noble white blossoms, in its slender habit, in the whorled arrangement of its branches, and in the length of time during which it continues in flower in its native regions, viz., from April to July, it differs from all its fellows of the same genus that inhabit northern India.
The flowers are four inches in length and four in diameter, with a broad trumpet lip. Their colour is purewhite, assuming a delicate rosy tinge as they become old, and sometimes becoming spotted with orange. They have an odour which resembles that of the lemon.
Of this and the following species Dr Hooker writes from Dorjiling, seven thousand feet above the sea:—"On the branches of the immense purple-flowered magnolia, (M. Campbellii,) and those of oaks and laurels,Rhododendron Dalhousiægrows epiphytally, a slender shrub bearing from three to six white lemon-scented bells, four and a half inches long and so many broad, at the end of each branch. In the same woods the scarlet Rhododendron (R. arboreum) is very scarce, and is outvied by the greatR. argenteum, which grows as a tree, forty feet high, with magnificent leaves twelve to fifteen inches long, deep green wrinkled above and silvery below, while the flowers are as large as those ofR. Dalhousiæand grow more in a cluster. I know nothing of the kind that exceeds in beauty the flowering branch ofR. argenteum, with its wide-spreading foliage and glorious mass of flowers."[222]
The latter, which is nearly equal toR. Dalhousiæin the size of its blossoms, and perhaps superior to it in other respects, is another white-flowered species. It is, as described above, a tree with large massive leaves of a silvery tint beneath. When young, they are exquisitely beautiful, being encased in long flesh-coloured cones of large scales, of very ornamental appearance. The flowers are three inches long, forming a compact globose head.
They secrete a large quantity of honey, which is said to be poisonous, as is also that ofR. Dalhousiæ.
The grandeur and beauty of the same genus are celebrated by Mr Low, as he saw the species growing in Borneo, where too their parasitic character struck him, as it had done Dr Hooker:—
"Perhaps the most gorgeous of the native plants are the various species of the genusRhododendron, which here assume a peculiar form, being found epiphytal upon the trunks of trees, as the genera of the tribeOrchidaceœ. This habit, induced probably by the excessive moisture of the climate, is not, however, confined to the Ericaceous plants, but also prevails with the generaFagria,Combretum, and many others, usually terrestrial; the roots of the Rhododendrons, instead of being, as with the species [which are] inhabitants of cold climates, small and fibrous, become large and fleshy, winding round the trunks of the forest trees; the most beautiful one is that which I have named in compliment to Mr Brooke. Its large heads of flowers are produced in the greatest abundance throughout the year: they much exceed in size those of any known species, frequently being formed of eighteen flowers, which are of all shades, from pale and rich yellow to a rich reddish salmon-colour; in the sun, the flowers sparkle with a brilliancy resembling that of gold dust.
"Four other species which I discovered are very gorgeous, but of different colours, one being crimson andanother red, and the third a rich tint between these two: of the fourth I have not yet seen the flowers."[223]
Take an example from another order. The Lightning-tree of Madagascar rises before us in the graphic pages of Mr Ellis:—
"But the most magnificent objects were the fine trees ofAstrapæa Wallichii, orviscosa. The name of this Malagasy plant was derived from the word for lightning, on account of the brilliancy of its flowers; and Sir Joseph Paxton and Dr Lindley have thus spoken ofA. Wallichii:—'One of the finest plants ever introduced. And when loaded with its magnificent flowers, we think nothing can exceed its grandeur.' I had seen a good-sized plant growing freely at Mauritius, but here it was in its native home, luxuriating on the banks of the stream, its trunk a foot in diameter, its broad-leaved branches stretching over the water, and its large, pink, globular, composite[224]flowers, three or four inches in diameter, suspended at the end of a fine down-covered stalk, nine inches or a foot in length. These, hanging by hundreds along the course of the stream, surpassed anything of the kind I had seen, or could possibly have imagined. I frequently met with theAstrapæaafterwards, but always growing near the water, and its branches frequently stretching over a lake or river."[225]
The Leguminous or Papilionaceous order presents many plants of striking beauty, both in foliage, which is often of extreme lightness and elegance, and also in blossom. They are among the gayest and most graceful of plants in all regions. The magnificent vegetation of the Mauritius contains one of notable glory, the Flamboyant, thus noticed by Ellis:—
"Conspicuous beyond all the rest is the stately and gorgeousPoinciana regia, compact-growing and regular in form, but retaining something of the acacia habit, rising sometimes to the height of forty or fifty feet, and, between the months of December and April, presenting, amidst its delicate pea-green pinnated leaves, one vast pyramid of bunches of bright, dazzling scarlet flowers. Seen sometimes over the tops of the houses, and at others in an open space, standing forth in truly regal splendour, this is certainly one of the most magnificent of trees. Its common name ismille fleurs, orflamboyant."[226]
I have had the delight of seeing thePoinciana pulcherrimain Jamaica, where it goes by the name of Flower-feuce, or sometimes, the "Pride of Barbadoes." It is, when in flower, a gorgeous mass of scarlet and orange, and it seemed to me the most magnificent thing in its way, that I had ever seen. It does not, however, attain the dimensions of its antipode, rarely exceeding those of a large shrub.
I know not what the Burmese tree is, which is alluded to in the following extracts from letters which I havereceived from my esteemed friend, Captain G. E. Bulger, of the 10th Regiment:—
"I shall be exceedingly obliged by your telling me whether you are familiar with the tree known in the West Indies and South America as the 'Bois Immortel;' and whether you think the leaf herewith sent belongs to it.
"During the cool season in Burmah, the forest presents a gorgeous sight, from the multitude of scarlet blossoms which a large kind of tree puts forth; and I am strongly inclined to think that this splendid ornament of the jungles is, at all events, allied to the Bois Immortel of the Western World.
"The tree I speak of begins to flower about the middle of December, at which time the leaves commence to wither and drop off. By the end of January, when it is in full bloom, there is hardly a leaf remaining, but it continues one mass of scarlet blossom until March. The flower is shaped like that of the pea.
"If you can enlighten me on this point I shall be indeed very much obliged."
I was compelled to confess my ignorance even of the South American beauty, and my friend thus replied:—
"I first read of the 'Bois Immortel' in 'Waterton's Wanderings,' and I subsequently saw a coloured representation of the tree in Mr Gould's magnificent work on Humming-Birds. I think the specific name was also given in that work, but it is some time ago, and I have almost forgotten what it was like. Since I saw these twoworks, I have heard officers speak of the splendour of the South American forests during the season of 'Le Bois Immortel,' and have heard more than one say that they believed nothing on earth could be more magnificent than 'matchless Trinidad' when these trees are in full bloom. The autumnal beauty of the North American woods is, doubtless, familiar to you, and I question very much whether there is anything richer or more lovely to be found even in South America."
Even the humblest orders of plants have the element of beauty bestowed on them with no niggard hand. Who would have expected, among theChenopodeæ, and, above all, in the lowly little Saltworts, to find such a glowing scene as Mr Atkinson describes?—
"We were now on a heavy sandy steppe—part of the Sackha Desert, which extends into the Gobi—and vegetation was so very scant, that even the steppe grass had disappeared. TheSalsolawas growing in a broad belt around the small salt lakes, its colour varying from orange to the deepest crimson. These lakes have a most singular appearance when seen at a distance. The sparkling of the crystallised salt, which often reflected the deep crimson around, gave them the appearance of diamonds and rubies set in a gorgeous framework. I rode round several times, admiring their beauty, and regretting that it was impossible to stay and visit a large lake, which I observed, ten or fifteen versts distant, surrounded with green, orange, and crimson."[227]
The microscope, too, will bring out beauties in flowers which the unassisted eye is incompetent fully to recognise. If we take a scarlet Geranium, or a purple Heartsease, the eye is delighted with the brilliancy of the colouring; but on placing a petal of either on a slip of glass, under a pretty high magnifying power, and reflecting the full rays of the sun through the object, the rich gorgeousness of the hue, the sparkling gem-like radiance of the surface, and the exquisitely-regular form of the round cells, with their clear interstices, form a spectacle of glorious beauty that almost surpasses the conception of one who has not seen it.
I shall close this chapter, which might easily have been expanded into a volume, with a reference to an humble and minute plant, whose fairy loveliness, combined with an almost unkillable hardiness of constitution, has won for it a place in every garden, however unpretending, and however ungenial in its locality,—the London-pride. This exquisite little Saxifrage, general favourite as it is, requires the microscope to bring out its beauties to advantage, but under a good instrument you cannot fail to be charmed with it. I have one before me at this moment, and will describe what I see.
First, I notice, on a cursory glance, that the whole plant is clothed with tiny hairs; I take one of the flower-stalks and examine these with a power of three hundred diameters. Each now becomes a stem of glass-like clearness, tapering upwards to a point, where it bears a richly crimson cup, and in this is seated a globule of colourlessglass, just as an acorn sits in its shell. The multitude of these organs—glandular hairs, the botanist calls them—standing up side by side, rising to varying heights, and displaying various degrees of development, is a very pleasing sight.
I turn to an unopened bud, putting on a lower power, and viewing it as an opaque object, with reflected light by the aid of the Lieberkuhn. Here are the parting sepals of the calyx, painted with rose-pink and pea-green, and studded all over with the knobbed hairs just noticed; the coloured surface is rough with granules, but it is the roughness of glass, for every knob gleams and sparkles with light. The corolla, a little white ball, displays its petals smoothly folded over each other, and their surface has the same appearance of granular glass as that of the calyx.
But now let me examine this blossom just expanded this morning,—the very first of the season, by the way. I must have a low power for this, eighty diameters, or so. Oh, how exquisite! The little saucer of five oval petals, each of snowy whiteness, bearing its bow of lovely crimson specks, with a spot of gamboge-yellow for the chord, and the whole sparkling with glassy points as before. The pale red germen in the centre, rising into two points of snow, their rosy tips pressed close together, as if the twins were kissing. The ten stamens, five short alternating with five long ones, and each bearing its pretty kidney-shaped anther of pale scarlet. No; all are not kidney-shaped; for here is one which has burst, and the grains of red pollen are seen covering its rough purple surface; and here is one stamen from the point of which the anther has gone, leaving only two or three pollen-grains adhering. Behind all, I see the sepals of the calyx, peeping out between the petals, and forming a fine dark background for them, and for the longer filaments.
And now I say to my readers, one and all,—you may not have the opportunity to examine the glorious tropical Orchids, or the gorgeous Flamboyant, but go and pluck a flower of the London-pride, and you will have before your eyes such a production of Divine handiwork as may well excite the admiration and adoration of an angel.
Vast as is this round world on which we live, its surface is not nearly large enough for all the living creatures which are ordained to inhabit it. Multitudes of animals do not walk on the ground, or swim in the waters, or fly in the air, but find the scene of their abode on or in the bodies of other animals. Multitudes of plants do not grow out of the soil, but attach themselves to other plants, and draw their sustenance and support thence. Nay, there are parasites upon parasites, and this, according to Hood, in an infinitely descending series.
"Great fleas have little fleasUpon their backs to bite 'em;And little fleas have lesser fleas;And soad infinitum."
"Great fleas have little fleasUpon their backs to bite 'em;And little fleas have lesser fleas;And soad infinitum."
Perhaps the poet's imagination ran a little ahead of his science here; but the idea of aninfinitesuccession of parasites, like nests of pill-boxes, is surely a funny one. There is nothing funny, however, in the thought "that even man," who was made in the image of God, "bears about in his vital organs various forms of loathsome creatures, which riot on his fluids, and consume the very substance of his tissues while ensconced where no efforts ofhis can dislodge them, no application destroy them. So it is; and few physical facts are better calculated to humble man, and stain the pride of his glory, than to feel that he may at any moment be nourishing a horrid tape-worm in his alimentary canal, or that his muscles may be filled with millions of microscopictrichinæ.
I will not dwell on these; though, if I were writing a book of pure science, there is a wondrous array of facts of the most striking and interesting character, connected with the structure, the metamorphoses, and the habits, of the Entozoic Worms, which I might present to my readers. It is more pleasant to consider other facts, perhaps not less marvellous, which, as they do not come quite so home to our personal feelings, will not excite horror and disgust in our minds.
Theeconomyof creation is remarkable. He who, by His divine manipulation converted five loaves and two small fishes into a hearty meal for five thousand men, besides women and children, and who could, with the same ease have made them a hundred times as much, said, when the meal was over, "Gather up the fragments, that nothing be lost." And, when He spread the earth with life, though His resources were infinite, He ordained that one object, itself healthfully enjoying life, and fulfilling its own proper ends of being, should be a microcosm, on which another range of life should find its sphere, and on which it should disport, as on an independent world. I have often admired, in the gorgeous tropical forests, what a wilderness of vegetation a singletree supports; what numbers of orchids and wild pines spring out of the forks, what creepers and lianes hang and twine about its branches, what elegant ferns cluster on the horizontal limbs, what snake-like cacti creep from bough to bough, what mosses, and jungermanniæ crowd in every crevice, what many-coloured lichens stud the rugged bark! And then animal life is swarming in all this great field of parasitic vegetation. Reptiles and birds, snails and slugs, insects and millepedes, and spiders and worms nestle by thousands in such prolific situations, so that a great old tropical tree, one of the giant figs or cotton-trees, is a very museum in itself.
And in my wanderings along the sea-edge here at home how often have I been amazed at the diverse population, plant and animal, which crowds a single oar-weed, or tangle! The stem fringed with delicate red-weeds, as the minuteRhodymeniæ, andPolysyphoniæ, andCallithamnia; the tortuous roots studded with Anemones, withFlustræandLepraliæ, and multitudes of otherPolyzoa, with tiny Polypes of many kinds, with Barnacles and Limpets, and sheltering small Crustacea, and Mites, and Annelids by scores.
Mr Darwin has an interesting passage on this subject, evoked by the profusion of parasitic life on the long sea-weed of Cape Horn (Macrocystis). "The number of living creatures" he remarks, "whose existence intimately depends on the Kelp is wonderful. A great volume might be written, describing the inhabitants of one of these beds of sea-weed. Almost all the leaves, excepting those thatfloat on the surface, are so thickly incrusted with corallines as to be of a white colour. We find exquisitely delicate structures, some inhabited by simple hydra-like polypi, others by more organised kinds, and beautiful compound Ascidiæ. On the leaves also, various patelliform shells, Trochi, uncovered molluscs, and some bivalves are attached. Innumerable crustacea frequent every part of the plant. On shaking the great entangled roots, a pile of small fish, shells, cuttle-fish, crabs of all orders, sea-eggs, star-fish, beautiful Holuthuriæ, Planariæ, and crawling nereidous animals of a multitude of forms, all fall out together. Often as I recurred to a branch of the kelp, I never failed to discover animals of new and curious structure. In Chiloe, where the kelp does not thrive very well, the numerous shells, corallines, and crustacea are absent; but there yet remain a few of the Flustraceæ, and some compound Ascidiæ; the latter, however, are of different species from those in Terra del Fuego: we here see the fucus possessing a wider range than the animals which use it as an abode. I can only compare these great aquatic forests of the southern hemisphere, with the terrestrial ones in the intertropical regions.
"Yet if in any country a forest was destroyed, I do not believe nearly so many species of animals would perish as would here, from the destruction of the kelp. Amidst the leaves of this plant numerous species of fish live, which nowhere else could find food or shelter: with their destruction the many cormorants and other fishing birds,the otters, seals, and porpoises, would soon perish also; and lastly, the Fuegian savage, the miserable lord of this miserable land, would redouble his cannibal feast, decrease in numbers, and perhaps cease to exist."
I have alluded to the epiphytic plants which are so abundant in the tropics, and which add so greatly to the gorgeousness of the forests there. The most remarkable, or, at all events, the best known, of these are theOrchideæ, to which, as I have already had occasion more than once to speak of them, I shall do little more than refer here. These establish themselves in the forks, upon the greater limbs, and even in the roughnesses of the bark of the trunk, adhering by their long, interlaced roots, which look like knotted whip-cord, and forming their bunches of psuedo-bulbs, whence their succulent, thick, but elegant leaves project,—a great tuft of verdure; and their fantastic flower-scapes wave in the air or droop with their weight of gorgeous bloom. Thus they derive their nourishment from the humid atmosphere alone, being dependent on the friendly tree only for support and elevation. Humidity seems essential to the vigour of these and most other forms of parasitic vegetation. In the deep shady, gloomy forests of Java, which constitute the zone of vegetation around the base of the mountains, these plants abound, where the air is heavy and damp with the vapours that cannot ascend, and where the density of the foliage is almost frightful; where heat, moisture, and a most extraordinarily deep and rich vegetable soil combine to produce wood of a fungus-like softness, and an inconceivable abundance of twining plants and epiphytes. In those forests, more especially where huge fig-trees constitute the principal part of the timber, intermingled with the most tropical forms of vegetation, such asSterculiaceæ,Sapindaceæ, andArtocarpeæ, tufts ofOrchideæattain a vast size and luxuriance, in company with Aroideous and Zinziberaceous plants.[228]In Demerara, Mr Henchman found masses ofOncidium altissimumandMaxillaria Parkeriof wide dimensions, and so densely growing as to defy any attempt at intrusion; and on the Spanish main he saw theEpidendrumknown as the "Spread Eagle" clasping enormous trees, and covering them from the top to the bottom.
The fig-trees, which are among the most gigantic of the tropical forest-trees, and which support an immense profusion of epiphytes, are themselves frequently parasitic and epiphyte in their early condition. It is not uncommon in Jamaica to see a network of roots partially embracing the trunk of some great tree, far up its column, and gradually creeping round and downward. I have seen an old wall so covered, presenting a very curious spectacle. The roots of a wide-spreading fig growing out of the summit of the wall, had spread over its perpendicular surface, down to the earth, all in the same plane, clinging to the wall; the chief roots were as thick as a man's leg, but subordinate roots had proceeded from one to another, anastomosing in all directions (if I may use such a term), so as to make a most elaborate network ofa multitude of meshes of various angular forms and sizes. These cross-roots wereat each extremityunited with the larger roots, and looked as if the whole network had been skilfully carved out of one solid plank of wood, by cutting out the areas or meshes, and rounding the component bars; the very bark that covered the whole was continuous, where the roots united, as if they had been always integrally one.
The only mode in which I can account for this singular phenomenon is the following hypothesis:—The seed of the tree was originally deposited on the summit of the wall, beneath the eaves. As it germinated, the roots ran down towards the earth, some perpendicularly, some diagonally; but all creeping along the surface of the wall, no roots having shot out from its perpendicular. As these roots increased, they sent out side rootlets, which, still running on the face of the wall, by and by came in contact with another of the primary roots. Then, instead of creepingoverit, as the roots of other trees would have done, the soft tip of the rootlet actually united with the substance of the root at the point of contact, the fibres of the two becoming interlaced, and their united surfaces gradually becoming covered with a common bark. The repetition of this process had produced the very curious wooden net which I have attempted to describe.
A still more remarkable example of this parasitic mode of growth I have seen in the same island. By the side of a mountain road was a large fig-tree, the base of whosetrunk was about thirty feet from the ground. Thence it reared itself up pillar-like towards the heavens, and spread abroad its vast horizontal array of branches across the road. From the same point there descended to the earth a hollow cone of roots, interwoven and anastomosed, especially at the upper parts, in the same manner as those of the boiling-house wall, but forming towards the bottom only three or four flattened irregular columns. Into the area inclosed by this network of roots a person might enter, for it was about six feet wide, and, looking up, behold the base of the trunk eight or ten yards above his head.
The explanation of this curious phenomenon depends upon the tendency just mentioned. On this site once stood a large tree of some other species, probably a cotton-tree (Eriodendron), or some other soft-timbered kind. The little scarlet berry of a Fig-tree was carried by some vagrant Banana-bird or Pigeon to its boughs, and there devoured. After the little truant had finished his morsel, he perhaps wiped his beak against the rough bark of the trunk, beside the branch on which he was seated. Some of the minute seeds, enveloped in mucilage, were thus left on the tree, which the rain presently washed down into the broad concavity of the forks, where, among moss and rotten leaves, it soon germinated and grew. The roots gradually crept down the trunk of the supporting tree, closely clinging to its bark, and by their interlacement at length formed a living case, enveloping it on every side, and penetrating the earth around its base.The growth of these, and also of the inclosed tree, daily induced a tighter and tighter pressure on the latter, which at length arrived at such a degree as to stop the circulation of the sap between the bark and the wood. Death, of course, was the result, and speedy decay reduced the supporting tree to a heap of mouldering dust: while the parasite, now able to maintain its own position by its hollow cone of roots, increased in size and strength, and overtopped its fellows of the forest;—a tree standing upon stilts.
A few years ago I was struck with the appearance of an East Indian species of the same genus in one of the conservatories at Kew. Three shoots had run up the wall, clinging so close, that the leaves looked as if they were actually glued to the bricks, one over the other, in the most regular manner. Yet, on examination, I saw that the leaves did not adhere at all; the only support was that of the tiny rootlets which proceeded laterally from each stem, which the leaves concealed. The appearance of the whole was so curious, with the pale growing bud peeping out from beneath the topmost leaf, that I was greatly attracted by it. The base of the plant was in a pot, but the attendant informed me that this connexion was about to be cut off, by severing each shoot at the point where it first seized the wall. The leaves above this point, by their superior size and vigour, shewed that the plant was already independent of its pot, and that it was capable of supporting itself, like a proper air-plant, by imbibition from the atmosphere alone, needing nothingmore than support in its upright position, which it obtained from the wall by its clinging aerial rootlets.
Every one who has wandered in a primeval forest of the tropics, whether in the eastern or the western hemisphere, has been struck by the inconceivable profusion of the climbers and twiners with which the trees are laced together. They are found from the thickness of a warship's cable to that of pack-thread; the stronger ones often uncouthly twisted together, and binding tree to tree. They are of the ordersMalpighaceæ,Apocyaneæ,Asclepiadeæ,Bignoniaceæ, &c., and often are adorned with the most brilliant flowers.
I have before cited descriptions of these wonderful lianes, as they occur in the forests of South America; my readers may like to peruse Sir Emerson Tennent's graphic sketch of those of Ceylon:—
"It is the trees of older and loftier growth that exhibit the rank luxuriance of these wonderful epiphytes in the most striking manner. They are tormented by climbing plants of such extraordinary dimensions that many of them exceed in diameter the girth of a man; and these gigantic appendages are to be seen surmounting the tallest trees in the forest, grasping their stems in firm convolutions, and then flinging their monstrous tendrils over the larger limbs till they reach the top, whence they descend to the ground in huge festoons, and, after including another and another tree in their successive toils, they once more ascend to the summit, and wind the whole into a maze of living network as massy as if formed bythe cable of a line-of-battle ship. When, by and by, the trees on which this singular fabric has become suspended give way under its weight, or sink by their own decay, the fallen trunk speedily disappears, while the convolutions of climbers continue to grow on, exhibiting one of the most marvellous and peculiar living mounds of confusion that it is possible to fancy. Frequently one of these creepers may be seen holding by one extremity the summit of a tall tree, and grasping with the other an object at some distance near the earth, between which it is strained as tight and straight as if hauled over a block. In all probability the young tendril had been originally fixed in this position by the wind, and retained in it till it had gained its maturity, where it has the appearance of having been artificially arranged as if to support a falling tree."[229]
Leaving the vegetable world, we may find some very curious examples of parasitism among Insects. Every one who has paid the slightest attention to this class of animals is aware that there are slender flies calledIchneumons, whose grubs are hatched and reared in the bodies of other insects. Many of these have the ovipositor greatly lengthened, and projecting like a very slender needle from the extremity of the abdomen. In some species, this needle-like organ is three or four times the entire length of the body; and this great longitude is intended to reach the pupæ of wasps and similar insects which inhabit deep holes. The needle itself is well worthy ofstudy. It is not simple, but composed of two pieces forming a sheath, which open and reveal a central finer filament, furnished at its tip (inPimpla manifestator, for example) with saw-like teeth. With this instrument, which possesses great elasticity and flexibility, the insect works, as a carpenter with his brad-awl, boring through the clay, with which the wasp has closed up the hole that contains her grub, until the tip of the ovipositor reaches the soft body of the insect. Into this it pierces, and deposits an egg, and is withdrawn. The slight puncture is scarcely felt by the grub, which continues to eat and grow; the inserted egg, however, presently hatches, and produces the ichneumon-grub, which begins to feed on the fat of the wasp-grub, instinctively avoiding the vital parts, until the latter has attained nearly its full size, and is ready to pass into the pupa state; when, its vigour being gone, it fails to accomplish the metamorphosis, the insidious intruder, now also full grown, taking its place, and by and by issuing from the hole a perfect Ichneumon.
How often has the enthusiastic young entomologist been subjected to sore disappointment by the parasitic habits of theseIchneumonidæ! He has obtained some fine caterpillar, a great rarity, and by dint of much searching of his Westwood or his Stainton, feels quite certain that it is the larva of some much-prized butterfly. He ascertains its leaf-food; which it eats promisingly; all goes on encouragingly. Surely it cannot be far from the pupa state now! When some morning he is horrified tobehold, instead of the chrysalis, a host of filthy little grubs eating their way out of the skin of his beautiful caterpillar, or covering its remains with their tiny yellow cocoons.
Some of these parasites are so minute that their young are hatched and reared in theeggsof other insects. Bonnet found that the egg of a butterfly, itself no bigger than the head of a minikin pin, was inhabited by several of the stranger grubs; for out of twenty such eggs, he says, "a prodigious quantity" of the grubs were evolved.
A very interesting tribe of insects, so diverse from all other known forms as to constitute an order among themselves, that of theStrepsiptera, passes its youth in the bodies of certain wild bees. Mr Kirby's account of his first detection of one of these, though often quoted, is so interesting that I must cite it afresh. "I had previously observed," he remarks, "upon bees something that I took to be a kind of mite (Acarus), which appeared to be immovably fixed just at the inosculations of the dorsal segments of the abdomen. At length, finding three or four upon anAndræna nigroænea, I determined not to lose the opportunity of taking one off to examine and describe; but what was my astonishment when, upon my attempting to disengage it with a pin, I drew forth from the body of the bee a white fleshy larva, a quarter of an inch in length, the head of which I had mistaken for an acarus (bee louse)! After I had examined one specimen, I attempted to extract a second; and the reader may imagine how greatly my astonishment was increased,when, after I had drawn it out but a little way, I saw its skin burst, and a head as black as ink, with large staring eyes and antennæ, consisting of two branches, break forth, and move itself quickly from side to side. It looked like a little imp of darkness just emerged from the infernal regions. My eagerness to set free from its confinement this extraordinary animal may be easily conjectured. Indeed, I was impatient to become better acquainted with so singular a creature. When it was completely disengaged, and I had secured it from making its escape, I set myself to examine it as accurately as possible; and I found, after a careful inquiry, that I had got a nondescript, whose very class seemed dubious."
Mr Newman, in an essay of much value,[230]has shewn that the larvæ of this tribe of insects are born alive, that they attach themselves to the abdomens of wild bees, nestling among the hair, and that they are thus introduced into the nest of the bee. Here it is somewhat uncertain how they are sustained at first, for at this time the bee-grubs are not hatched; probably they remain without food for some days, or devour a portion of the pollen and honey stored up. As soon, however, as the bee-grub is hatched, the Stylops-larva undergoes a metamorphosis, sheds its six legs, and becomes a footless maggot; it pierces the soft skin of the bee-grub, and feeds on its juices, till its maturity, as the Ichneumon on the body of the caterpillar.
When the perfect bee emerges in the following spring,it bears the full-grown Stylops, protruding from the rings of its abdomen. The latter is in pupa, all the organs being distinct and separate, but wrapped together, and inclosed in separate pellicles; very soon, it emerges, as described by Kirby, and escapes, leaving a great unsightly cavity in the body of the bee. This is the male: the female never escapes, but lays its eggs on the bee in which it has been reared, and then dies.
In the spring we frequently see among herbage a great uncouth beetle of a dark blue-black hue, with short wing-cases and long, heavy body, which discharges drops of yellow fluid when handled, and is therefore called the Oil-beetle (Melöe proscarabæus). The early stages of this beetle have much affinity with those of theStylops. The beetle lays a number of yellow eggs in a hole in the earth; these produce little active six-footed larvæ, resembling lice, which crawl to the summit of dandelion and other flowers in the sunshine, and await the visit of a bee. On the arrival of one, the active grub immediately clings to its body, and is carried to the nest, not, however, to introduce itself parasitically into the body of the bee-grub, but to feed on the provision which the parent bee has stored up for its own young. Thus it becomes very fat, and grows to a size much larger than that of the full-grown bee-grub, having early dropped its six long clinging legs, which, having performed their proper function in catching hold of a bee, are no longer needed. It changes to a perfect beetle in autumn, lies in the bee's nest all the winter, and emerges in the spring.
The large jelly-like Medusæ which in summer are seen floating around our coasts, driving themselves along by alternate contractions and expansions of their umbrella, are frequently infested by little creatures of widely different organisation, Crustaceans belonging to the generaHyperia and Metoecus. On the beautifulChrysaoraof the southern coast I have seen theMetoecus medusarum, a little shrimp about half-an-inch in length, with enormous lustrous green eyes, which takes up his residence in the cavities of the sub-umbrella,—dwelling in them as in so many spacious and commodious apartments, of which he takes possession, evidently without asking leave of the landlord, or paying him even the compliment of a peppercorn rent. Here he snugly ensconces himself, and feels so much at home, that he is not afraid to leave his dwelling now and then, to take a swim in the free water, returning to his chamber after his exercise; and here he rears his numerous family, which, in the form of tiny white specks, very much unlike their parents in shape, stud the membranes of the jelly-fish.
But, what is stranger still, Mr M'Cready has recently discovered in the harbour of Charleston in North America, aMedusawhich is parasitic upon anotherMedusa.Cunina octonariadoes not swim freely in the water, but inhabits the cavity of the bell ofTurritopsis nutricula. "Not only does the latter furnish a shelter and dwelling-place for the larvæ during their development; it also serves as their nurse, by allowing the parasites, whilst adhering by their tentacles, to drawnourishment out of its mouth by means of a large proboscis. In point of fact, the relation between them is of so unprecedented a nature, that the author may well be excused for having at first taken the impudent parasite for the gemmiparous progeny of the sheltering Medusa. The youngest state of this parasitic Medusa observed by the author formed a ciliated body of clavate form, adhering to the cavity of the bell by means of the slender stalk in which it terminated. The first change consists in the emission, from the thick end, of two slender flexible tentacles, and in the formation of a central cavity by liquefaction. At this stage of development, the author frequently observed gemmation taking place at the thicker end, sometimes frequently repeated. Subsequently the number of tentacles becomes doubled. These bend together over the clavate extremity, and are then employed, instead of the thin end of the body, in adhering to the cavity of the sheltering Medusa. The thin extremity then acquires a mouth, and may be recognised as a stomachal peduncle, which is employed, as above indicated, in obtaining nourishment. The morphological nature of the proboscis becomes still more distinct when, after the lapse of some little time, an annular fold makes its appearance immediately under the tentacles, which is recognisable from its form, and from the formation in it of (eight) otolithic capsules, as the first indication of the future bell. Simultaneously with the otolithic capsules, four rudimentary tentacles make their appearance between the four tentacles. The Medusa remains in this stage of development for a long time. The bell gradually becomes more freely developed, and at last, by the reduction and entire disappearance of the stomachal peduncle, becomes the most essential part of the Medusa, after it has left its previous dwelling-place in the bell of theTurritopsis. The bell nevertheless retains for some time its earlier lobed form and unequal tentacles."[231]
More remarkable even than this association is the fact that certain true Fishes habitually reside in the stomachs of star-fishes. This circumstance, which had been observed in the Oriental Archipelago by MM. Quoy and Gaimard, and by Dr Bleeker, has recently been confirmed by Dr Doleschall, who has written a very interesting Memoir on it.
This learned naturalist states that the fact of the connexion between the fish and the star-fish is well known to most of the fishermen in Amboyna, and that he was able to obtain a sufficiency of specimens for examination; but as the star-fishes (and with them the fishes) speedily died in confinement, he was unable to make continuous observations upon them in a living state. Of the results of his observations he gives the following summary:—
"The fish stands to the star-fish in a definite relation which cannot be the object of observation. Why the little fish should always seek the stomachal cavity of one and the same species of star-fish, and not that of various species, is a mystery. It is well known that Crustaceans of the genusPagurusinhabit the empty shells of Mollusca; but we find on the shore the same species ofPagurusin the shells of the most various genera and species.
"I have never met withOxybeles gracilis, on the contrary, in any other species of star-fish thanCulcita discoidea. The fish was described by Bleeker under the above name in 'Natuurkundig Tijdschrift,' vii., p. 162. The author proceeds to state that neither he nor any one else in Amboyna has ever captured the fish under other circumstances, or while swimming freely in the sea; but upon this Dr Bleeker remarks that many of his specimens ofFierasfer Brandesii, and all those ofFierasfer (Oxybeles) gracilisandF. lumbricoides, were obtained by him along with other fishes, and were probably taken while swimming freely in the sea.
"Upon the habits ofOxybeles gracilisthe author goes on to say that it is certain that this animal passes the greater part of its existence in the stomach of the star-fish, rarely shewing itself outside of this, and then probably at night. That it does come out occasionally, appears from the fact that in two cases the author observed the fish with a portion of its body outside the cavity of the star-fish, and in the act of creeping in.
"The same observations shewed that the fish, in returning to its concealment, passes along the furrow of the lower surface of one of the arms leading to the mouth of the star-fish, which is wide enough, when the tentacles are retracted, to leave room for the passage of the slender body of theOxybeles. This fact likewise proves that theOxybelesdoes not get into the stomach of theCulcitaby accident.
"If a livingCulcitabe cut in two, the fish is seen moving freely in the cavity of its body. If it be taken out, it immediately seeks the shade. If the two halves of theCulcita(still alive) be placed in the water, the fish will soon be seen to draw towards them, in order to get into the cavity of the star-fish. When exposed to the light, it is uneasy, and its iris contracts excessively. The author never found two fishes in the same star-fish.
"In most of the fishes examined by him, the author found the stomach empty; it was full only in one. The contents of the stomach had the appearance of a lump of fat, and consisted of half-digested muscle. Under the microscope, striated muscular fibres could be detected, and the author thinks that they belonged to the muscles of a fish. This circumstance proves thatOxybelesdoes not feed upon the chyle of the star-fish, but that its nourishment is analogous to that of other fishes. Whether it seizes upon the fishes taken by the star-fish for its own nourishment must be determined by further investigations.
"The author's observations establish—
"1. ThatOxybeles gracilisis not a true parasite.
"2. That it passes the greater part of its life in the stomach ofCulcita discoidea, as is also indicated by the unusually pale colour of the fish.
"3. That, however, it can come out, either to seek nourishment, or for the purpose of reproduction.
"4. That it returns to the mouth along the furrow on the ventral surface of the arms.
"5. That it is very sensitive to light.
"6. That it feeds upon other animals.
"In fresh water the animals live for about half-an-hour. The pigment upon the peritoneum exhibits under the microscope the most beautiful stellate forms. The fish possesses a swimming-bladder."[232]
Some very curious instances of parasitism occur, in which one kind of creature compels or induces another creature to labour for its special benefit. Indeed, in all cases, the parasite is benefited by the functions of the supporter; but, in the cases I refer to, the slavery is more special and more apparent.
There is a large species of Crab (Dromia) found in the West Indies, which is invariably found covered with a dense mass of sponge. The sponge is found to have grown in such a manner as to fit every prominence and cavity of the crab, exactly as if a plastic material had been moulded on it, yet it is not adherent to it, but is merely held in position by the hindmost pair of feet, which in this genus of crabs, are turned upwards, and apparently serve no other purpose than that of hooks to hold on the spongein situ.
On our own shores we are familiar with the Hermit crabs making use of various kinds of univalve shells as houses to protect their softer hindparts; but in many of these cases there is a third party in the transaction, whichis made to work for the crab's especial advantage. The shell of the mollusk is sometimes covered with a sort of fleshy polype-mass (Hydractinia echinata), which is parasitic on the shell. The shell, however, being tenanted also by the active crab, the polype, as it grows, moulds itself on the crab's body, and thus extends the dimensions of its house, so that it has no necessity either to enlarge its dwelling by the absorption of part of the interior shell-wall, or to leave this shell and search for one of ampler size, as other Hermit-crabs are obliged to do who have not the advantage of so accommodating a fellow-lodger. "One can understand," says Dr Gray, "that the Crab may have the instinct to search for shells, on which the coral [polype] has begun to grow; but this will scarcely explain why we never find the [polype] except on shells in which Hermit-crabs have taken up their residence."[233]
Small Annelids and Crustaceans not unfrequently burrow into the stony walls of corals; but Dr Gray records a much more uncommon case, from the Guilding collection. "It is an expanded coral, which forms a thin surface on the top of another coral, and is furnished with a number of small, depressed, horizontal cases, opening with an oblong mouth. Some of these contain within them a small, free, crustaceous animal, aCymothoa, which nearly fits the case; and it is evident that, by their moving backwards and forwards on the surface, they have caused the animal of the coral to form one of these cases for the protection of each specimen."[234]
The manner in which this result is obtained is thus explained—"The animals which form their habitation in corals, appear to begin their domicile in the same way as the barnacles before referred to; they take advantage of the soft and yielding nature of the animals which form the corals, &c., and taking up a lodgement in their body, all they have to do is to keep a clear passage in it, either by the moving backwards and forwards, the exertion of their limbs, or the ingress or egress of water to and from their bodies, and in time, as the coral is secreted by the animal, it will form a wall round them; but if, by any accident, the parasite animal should not keep a passage from the coral to the surface of the body of the animal clear, which it must be constantly induced to do, since by this means it procures food, the coral animal will in a very short time close over it and bury it alive in the mass of the coral; and this, from the number of these animals, of all sizes and in different stages of growth, which are to be found in the substance of the large and massive corals, must often be occurring. Thus the Italian romance is often literally fulfilled in nature."
Certain birds are parasitic, in this sense, that they compel or induce other birds to perform the labour of incubation and of rearing their young. The Rhea or Ostrich of South America is parasitical on its own species; the females laying each several eggs in the nests of several other females, and the male ostrich taking all the cares of incubation. More familiar examples, however, occur in our own Cuckoo, and in the Cowpen birds (MolothruspecorisandM. niger) of North and South America. "These fasten themselves," as has been remarked by Mr Swainson, "on another living animal, whose animal heat brings their young into life, whose food they live upon, and whose death would cause theirs during the period of infancy."
The habit, at least in the case of the European Cuckoo, is so well known, that I need not do more than merely allude to the fact, that the female seeks for the nests of other insect-eating birds, always much smaller than itself, and deposits its own eggs,—a single egg in each; that this stranger egg is hatched by the foster-mother with all care, and the young bird is nurtured with all tenderness even at the expense of its own proper eggs and young, which in general are sacrificed in the course of the process. Every schoolboy knows these facts, but few perhaps have ever suspected the existence of a romantic feeling of love and fealty in the little bird towards the cuckoo herself, prompting the rendering of the service required as a coveted honour. Yet a naturalist has communicated to Mr Yarrell some facts which certainly look this way; and because they are indubitably the very romance of natural history, I cite them, leaving my readers to judge of their value.
"As you have contributed," writes Mr W. C. Newby of Stockton, "so much to the information and amusement of the numerous class of readers who take an interest in subjects of natural history, I consider it my duty to communicate first to you, what appears to me a new factin the habits and character of that general favourite the cuckoo.
"An egg of this bird was brought to me on the 6th instant, which had been taken from the nest of the yellow bunting, at a short distance from this town, and the boy who got the egg gave the following account, which, I think, may be relied on. When bird-nesting the previous Saturday, he found a nest of the gold spink (a local name for the yellow bunting) with the young birds just hatched. On visiting the nest the following day, he flushed the old bird, having seen her sitting on it, but the young birds were all excluded, and were lying dead near; and to his surprise, a single egg—the one he brought to me—occupied the place of the callow brood. He took away the egg (which is now in my possession) so that it is impossible to corroborate the statement in any degree. The above circumstance was first named to me by Tom Green, a well-known character and naturalist in this town, whom I have always found to be accurate in his observations on birds, and by him I was referred to the boy. On my objecting to Green that the accident appeared incredible, because unnatural, and contrary to strong parental instinct, he replied, "Ay, sir, but little birds are mightily ta'en up with a cuckoo; they'll awmost dee out for them;" and he related the following fact which came under his own observation. When out with his gun, collecting birds to stuff, (animal-preserving being one of his many trades), he shot at and wounded a cuckoo, which, after flying some distance, fell upon a hedge with its wings outstretched:the attendant bird, which in this case was one of the pipits, continued in the flight of its patron after the shot, and when Green approached, he found it sitting on the body of the dead cuckoo.[235]