THE MOUNDS OF THE WHITE ANT.THE MOUNDS OF THE WHITE ANT.
But what has this to do with earth or with agriculture? The most important point in the work of the white ant remains to be noted. I have already said that the white ant is never seen. Why he should have such a repugnance to being looked at is at first sight a mystery, seeing that he himself is stone blind. But his coyness is really due to the desire for self-protection, for the moment his juicy body shows itself above ground there are a dozen enemies waiting to devour it. And yet the white ant can never procure any food until it comes above ground. Nor will it meet the case for the insect to come to the surface under the shadow of night. Night in the tropics, so far as animal life is concerned, is as the day. It is the great feeding time, the great fighting time, the carnival of the carnivores, and of all beasts, birds, and insects of prey from the least to the greatest. It is clear then that darkness is no protection to the white ant; and yet without coming out of the ground it cannot live. How does it solve the difficulty? It takes the ground out along with it. I have seen white ants working on the top of a high tree, and yet they were underground. They took up some of the ground with them to the tree-top; just as the Esquimaux heap up snow, building it into the low tunnel-huts in which they live, so the white ant collects earth, only in this case not from the surface but from some depth underneath the ground, and plaster it into tunnelled ways. Occasionally these run along the ground, but more often mount in endless ramifications to the top of trees, meandering along every branch and twig, and here and there debouching into large covered chambers which occupy half the girth of the trunk. Millions of trees in some districts are thus fantastically plastered over with tubes, galleries, and chambers of earth, and many pounds weight of subsoil must be brought up for the mining of even a single tree. The building material is conveyed by the insects up a central pipe with which all the galleries communicate, and which at the downward end connects with a series of subterranean passages leading deep into the earth. The method of building the tunnels and covered ways is as follows:—At the foot of a tree the tiniest hole cautiously opens in the ground close to the bark. A small head appears with a grain of earth clasped in its jaws. Against the tree-trunk this earth-grain is deposited, and the head is withdrawn. Presently it reappears with another grain of earth, this is laid beside the first, rammed tight against it, and again the builder descends underground for more. The third grain is not placed against the tree, but against the former grain; a fourth, a fifth, and a sixth follow, and the plan of the foundation begins to suggest itself as soon as these are in position. The stones or grains or pellets of earth are arranged in a semicircular wall, the termite, now assisted by three or four others, standing in the middle between the sheltering wall and the tree, and working briskly with head and mandible to strengthen the position. The wall in fact forms a small moon-rampart, and as it grows higher and higher it soon becomes evident that it is going to grow from a low battlement into a long perpendicular tunnel running up the side of the tree. The workers, safely ensconced inside, are now carrying up the structure with great rapidity, disappearing in turn as soon as they have laid their stone and rushing off to bring up another. The way in which the building is done is extremely curious, and one could watch the movement of these wonderful little masons by the hour. Each stone as it is brought to the top is first of all covered with mortar. Of course, without this the whole tunnel would crumble into dust before reaching the height of half an inch; but the termite pours over the stone a moist sticky secretion, turning the grain round and round with its mandibles until the whole is covered with slime. Then it places the stone with great care upon the top of the wall, works it about vigorously for a moment or two till it is well jammed into its place, and then starts off instantly for another load.
Peering over the growing wall, one soon discovers one, two, or more termites of a somewhat larger build, considerably longer and with a very different arrangement of the parts of the head, and especially of the mandibles. These important-looking individuals saunter about the rampart in the most leisurely way, but yet with a certain air of business, as if perhaps the one was the master of works and the other the architect. But closer observation suggests that they are in no wise superintending operations, nor in any immediate way contributing to the structure, for they take not the slightest notice either of the workers or the works. They are posted there in fact as sentries, and there they stand, or promenade about, at the mouth of every tunnel, like sister Ann, to see if anybody is coming. Sometimes somebody does come in the shape of another ant—the real ant this time, not the defencelessNeuropteron, but some valiant and belted knight from the warlikeFormicidæ. Singly, or in troops, this rapacious little insect, fearless in its chitinous coat of mail, charges down the tree-trunk, its antennæ waving defiance to the enemy, and its cruel mandibles thirsting for termite blood. The worker white ant is a poor defenceless creature, and blind and unarmed, would fall an immediate prey to these well-drilled banditti, who forage about in every tropical forest in unnumbered legion. But at the critical moment, like Goliath from the Philistines, the soldier termite advances to the fight. With a few sweeps of its scythe-like jaws it clears the ground, and while the attacking party is carrying off its dead, the builders, unconscious of the fray, quietly continue their work. To every hundred workers in a white ant colony, which numbers many thousands of individuals, there are perhaps two of these fighting men. The division of labor here is very wonderful, and the fact that besides these two specialized forms there are in every nest two other kinds of the same insect, the kings and queens, shows the remarkable height to which civilization in these communities has attained.
But where is this tunnel going to, and what object have the insects in view in ascending this lofty tree? Thirty feet from the ground, across innumerable forks, at the end of a long branch, are a few feet of dead wood. How the ants know it is there, how they know its sap has dried up, and that it is now fit for the termites' food, is a mystery. Possibly they do not know, and are only prospecting on the chance. The fact that they sometimes make straight for the decaying limb argues in these instances a kind of definite instinct; but, on the other hand, the fact that in most cases the whole tree, in every branch and limb, is covered with termite tunnels, would show perhaps that they work most commonly on speculation, while the number of abandoned tunnels, ending on a sound branch in acul de sac, proves how often they must suffer the usual disappointments of all such adventurers. The extent to which these insects carry on their tunnelling is quite incredible until one has seen it in nature with his own eyes. The tunnels are, perhaps, about the thickness of a small-sized gas-pipe, but there are junctions here and there of large dimensions, and occasionally patches of earthwork are found embracing nearly the whole trunk for some feet. The outside of these tunnels, which are never quite straight, but wander irregularly along stem and branch, resembles in texture a coarse sandpaper; and the color, although this naturally varies with the soil, is usually a reddish brown. The quantity of earth and mud plastered over a single tree is often enormous; and when one thinks that it is not only an isolated specimen here and there that is frescoed in this way, but often the whole of the trees of a forest, some idea will be formed of the magnitude of the operations of these insects and the extent of their influence upon the soil which they are thus ceaselessly transporting from underneath the ground.
In travelling through the great forest of the Rocky Mountains or of the Western States, the broken branches and fallen trunks strewing the ground breast-high with all sorts of decaying litter frequently make locomotion impossible. To attempt to ride through these western forests, with their meshwork of interlocked branches and decaying trunks, is often out of the question, and one has to dismount and drag his horse after him as if he were clambering through a woodyard. But in an African forest not a fallen branch is seen. One is struck at first at a certain clean look about the great forests of the interior, a novel and unaccountable cleanness, as if the forest-bed was carefully swept and dusted daily by unseen elves. And so, indeed, it is. Scavengers of a hundred kinds remove decaying animal matter—from the carcase of a fallen elephant to the broken wing of a gnat—eating it, or carrying it out of sight, and burying it on the deodorizing earth. And these countless millions of termites perform a similar function for the vegetable world, making away with all plants and trees, all stems, twigs, and tissues, the moment the finger of decay strikes the signal. Constantly in these woods one comes across what appear to be sticks and branches and bundles of faggots, but when closely examined they are seen to be mere casts in mud. From these hollow tubes, which preserve the original form of the branch down to the minutest knot or fork, the ligneous tissue is often entirely removed, while others are met with in all stages of demolition. Examine the section of an actual specimen, which is not yet completely destroyed, and from which the mode of attack may be easily seen. The insects start apparently from two centres. One company attacks the inner bark, which is the favorite morsel, leaving the coarse outer bark untouched, or more usually replacing it with grains of earth, atom by atom, as they eat it away. The inner bark is gnawed off likewise as they go along, but the woody tissue beneath is allowed to remain to form a protective sheath for the second company who begin work at the centre. This second contingent eats its way outward and onward, leaving a thin tube of the outer wood to the last, as props to the mine, till they have finished the main excavation. When a fallen trunk lying upon the ground is the object of attack, the outer cylinder is frequently left quite intact, and it is only when one tries to drag it off to his camp-fire that he finds to his disgust that he is dealing with a mere hollow tube a few lines in thickness filled up with mud.
NESTS OF WHITE ANTSNESTS OF WHITE ANTS
But the works above ground represent only a part of the labors of these slow-moving but most industrious of creatures. The arboreal tubes are only the prolongation of a much more elaborate system of subterranean tunnels, which extend over large areas and mine the earth sometimes to a depth of many feet or even yards.
The material excavated from these underground galleries and from the succession of domed chambers—used as nurseries or granaries—to which they lead, has to be thrown out upon the surface. And it is from these materials that the huge ant-hills are reared, which form so distinctive a feature of the African landscape. These heaps and mounds are so conspicuous that they may be seen for miles, and so numerous are they and so useful as cover to the sportsman, that without them in certain districts hunting would be impossible. The first things, indeed, to strike the traveller in entering the interior are the mounds of the white ant, now dotting the plain in groups like a small cemetery, now rising into mounds, singly or in clusters, each thirty or forty feet in diameter and ten or fifteen in height; or, again, standing out against the sky like obelisks, their bare sides carved and fluted into all sorts of fantastic shapes. In India these ant-heaps seldom attain a height of more than a couple of feet, but in Central Africa they form veritable hills, and contain many tons of earth. The brick houses of the Scotch mission-station on Lake Nyassa have all been built out of a single ants' nest, and the quarry from which the material has been derived forms a pit beside the settlement some dozen feet in depth. A supply of bricks, as large again, could probably still be taken from this convenient depôt; and the missionaries on Lake Tanganyika and onwards to Victoria Nyanza have been similarly indebted to the labors of the termites. In South Africa the Zulus and Kaffirs pave all their huts with white-ant earth; and during the Boer war our troops in Praetoria, by scooping out the interior from the smaller beehive-shaped ant-heaps, and covering the top with clay, constantly used them as ovens. These ant-heaps may be said to abound over the whole interior of Africa, and there are several distinct species. The most peculiar as well as the most ornate, is a small variety from one to two feet in height, which occurs in myriads along the shores of Lake Tanganyika. It is built in symmetrical tiers, and resembles a pile of small rounded hats, one above another, the rims depending like eaves, and sheltering the body of the hill from rain. To estimate the amount of earth per acre raised from the water-line of the subsoil by white ants would not in some districts be an impossible task; and it would be found, probably, that the quantity at least equalled that manipulated annually in temperate regions by the earthworm.
These mounds, however, are more than mere waste-heaps. Like the corresponding region underground, they are built into a meshwork of tunnels, galleries, and chambers, where the social interests of the community are attended to. The most spacious of these chambers, usually far underground, is very properly allocated to the head of the society, the queen. The queen-termite is a very rare insect, and as there are seldom more than one, or at most two, to a colony, and as the royal apartments are hidden far in the earth, few persons have ever seen a queen, and indeed most, if they did happen to come across it, from its very singular appearance, would refuse to believe that it had any connection with white ants. It possesses, indeed, the true termite head, but there the resemblance to the other members of the family stops, for the size of the head bears about the same proportion to the rest of the body as does the tuft on his Glengarry bonnet to a six-foot Highlander. The phenomenal corpulence of the royal body in the case of the queen-termite is possibly due in part to want of exercise, for once seated upon her throne she never stirs to the end of her days. She lies there, a large, loathsome, cylindrical package, two or three inches long, in shape like a sausage, and as white as a bolster. Her one duty in life is to lay eggs, and it must be confessed she discharges her function with complete success, for in a single day her progeny often amounts to many thousands, and for months this enormous fecundity never slackens. The body increases slowly in size, and through the transparent skin the long folded ovary may be seen, with the eggs, impelled by a peristaltic motion, passing onward for delivery to the workers who are waiting to carry them to the nurseries where they are hatched. Assiduous attention, meantime, is paid to the queen by other workers, who feed her diligently, with much self-denial stuffing her with morsel after morsel from their own jaws. A guard of honor in the shape of a few of the larger soldier-ants is also in attendance as a last and almost unnecessary precaution. In addition, finally, to the soldiers, workers, and queen, the royal chamber has also one other inmate—the king. He is a very ordinary-looking insect, about the same size as the soldiers, but the arrangement of the parts of the head and body is widely different, and like the queen he is furnished with eyes.
Let me now attempt to show the way in which the work of the termites bears upon the natural agriculture and geology of the tropics. Looking at the question from the large point of view, the general fact to be noted is, that the soil of the tropics is in a state of perpetual motion. Instead of an upper crust, moistened to a paste by the autumn rains, and then baked hard as adamant in the sun; and an under soil hermetically sealed from the air and light, and inaccessible to all the natural manures derived from the decomposition of organic matters—these two layers being eternally fixed in their relations to one another—we have a slow and continued transference of the layers always taking place. Not only to cover their depredations, but to dispose of the earth excavated from the underground galleries, the termites are constantly transporting the deeper and exhausted soils to the surface. Thus there is, so to speak, a constant circulation of earth in the tropics, a ploughing and harrowing, not furrow by furrow and clod by clod, but pellet by pellet and grain by grain.
Some idea of the extent to which the underlying earth of the tropical forests is thus brought to the surface will have been gathered from the facts already described; but no one who has not seen it with his own eyes can appreciate the gigantic magnitude of the process. Occasionally one sees a whole trunk or branch, and sometimes almost an entire tree, so swathed in red mud that the bark is almost completely concealed, the tree looking as if it had been taken out bodily and dipped in some crystallizing solution. It is not only one tree here and there that exhibits the work of the white ant, but in many places the whole forest is so colored with dull red tunnels and patches as to give a distinct tone to the landscape—an effect which, at a little distance, reminds one of theabend-rothin a pine forest among the Alps. Some regions are naturally more favorable than others to the operations of the termites; and to those who have only seen them at work in India or in the lower districts of Africa this statement may seem an exaggeration. But on one range of forest-clad hills on the great plateau between Lake Nyassa and Tanganyika I have walked for miles through trees, every one of which, without exception, was ramified, more or less, with tunnels. The elevation of this locality was about 5000 feet above the sea and the distance from the equator some 9°; but nowhere else have I seen a spot where the termites were so completely masters of the situation as here. If it is the case that in these, the most elevated regions of Central Africa, the termite colonies attain their maximum development, the fact is of much interest in connection with the geological and agricultural function which they seem to serve; for it is here precisely, before the rivers have gathered volume, that alluvium is most wanting; it is here that the tiny headwaters of these same rivers collect the earth for subsequent distribution over the distant plains and coasts; and though the white ant may itself have no power, in the first instance, of creating soil, as a denuding and transporting agent, its ministry can scarcely be exaggerated. If this is its function in the economy of nature, it is certainly clear that the insect to which this task is assigned is planted where, of all places, it can most effectively fulfil the end.
The direct relation of the termites' work to denudation will still further appear if we try to imagine the effect upon the accumulations of earth pellets and grains of an ordinary rainy season. For two or three months in the tropics, though intermittently, the rains lash the forests and soils with a fury such as we, fortunately, have little idea of. And though the earthworks, and especially the larger ant-hills, have marvellous resisting properties, they are not invulnerable, and must ultimately succumb to denuding agents. The tunnels, being only required for a temporary purpose, are made substantial enough only to last the occasion. And in spite of the natural glue which cements the pellets of earth together, the structure, as a whole, after a little exposure, becomes extremely friable, and crumbles to pieces at a touch. When the earth-tubes crumble into dust in the summer season the debris is scattered over the country by the wind, and this way tends to increase and refresh the soil. During the rains, again, it is washed into the rivulets and borne away to fertilize with new alluvium the distant valleys, or carried downward to the ocean, where, along the coast line, it "sows the dust of continents to be." Herodotus, with equal poetic and scientific truth, describes Egypt as "the gift of the Nile." Possibly had he lived to-day he might have carried his vision farther back still, and referred some of it to the labors of the humble termites in the forest slopes about Victoria Nyanza.
THE WAYS OF AFRICAN INSECTS.
Mimicry is imposture in nature. Carlyle in his blackest visions of "shams and humbugs" among human kind never saw anything so finished in hypocrisy as the naturalist now finds in every tropical forest. There are to be seen creatures, not singly, but in tens of thousands, whose very appearance, down to the minutest spot and wrinkle, is an affront to truth, whose every attitude is a pose for a purpose, and whose whole life is a sustained lie. Before these masterpieces of deception the most ingenious of human impositions are vulgar and transparent. Fraud is not only the great rule of life in a tropical forest, but the one condition of it.
Although the extraordinary phenomena of mimicry are now pretty generally known to science, few workers have yet had the opportunity of studying them in nature. But no study in natural history depends more upon observation in the field; for while in the case of a few mimetic forms—theHeliconidæ, for example—the imitated form is also an insect, and the two specimens may be laid side by side in the cabinet at home, the great majority of mimetic insects are imitations of objects in the environment which cannot be brought into comparison with them in the drawers of a museum. Besides this, it is not only the form but the behavior of the mimetic insect, its whole habit and habitat, that have to be considered; so that mere museum contributions to mimicry are almost useless without the amplest supplement from the field naturalist. I make no further apology, therefore, for transcribing here a few notes bearing upon this subject from journals written during a recent survey of a region in the heart of Africa—the Nyassa-Tanganyika plateau—which has not yet been described or visited by any naturalist.
The preliminaries of the subject can be mastered in a moment even by the uninitiated, and I may therefore begin with a short preface on animal coloring in general. Mimicry depends on resemblances between an animal and some other object in its environment of which it is a practical gain to the creature to be a more or less accurate copy. The resemblance may be to any object, animate or inanimate. It may be restricted to color, or it may extend to form, and even to habit; but of these the first is by far the most important.
Apart from sexual selection, color in animals mainly serves two functions. It is either "protective" or "warning." The object of the first is to render the animal inconspicuous, the object of the second is the opposite—to make it conspicuous. Why it should be an object with some animals to be palpably exposed will be apparent from the following familiar instance of "warning" coloration. There are two great families of butterflies, theDanaidæandAcraiedæ, which are inedible owing to the presence in their bodies of acrid and unwholesome juices. Now to swallow one of these creatures—and birds, monkeys, lizards, and spiders are very fond of butterflies—would be gratuitous. It would be disappointing to the eater, who would have to disgorge his prey immediately, and it would be an unnecessary sacrifice of the subject of the experiment. These butterflies, therefore, must have their disagreeableness in some way advertised, and so they dress up with exceptional eccentricity, distinguishing themselves by loud patterns and brilliant colorings, so that the bird, the monkey, and the rest can take in the situation at a glance. These animated danger-signals float serenely about the forests with the utmost coolness in the broadest daylight, leisureliness, defiance and self-complacency marking their every movement, while their duskier brethren have to hurry through the glades in terror of their lives. For the same reason, well-armed or stinging insects are always conspicuously ornamented with warning colors. The expense of eating a wasp, for instance, is too great to lead to a second investment in the same insect, and wasps therefore have been rendered as showy as possible so that they may be at once seen and as carefully avoided. The same law applies to bees, dragonflies, and other gaudy forms; and it may be taken as a rule that all gayly-colored insects belong to one or other of these two classes: that is, that they are either bad eating or bad-stingers. Now the remarkable fact is that all these brilliant and unwholesome creatures are closely imitated in outward apparel by other creatures not themselves protected by acrid juices, but which thus share the same immunity. That these are cases of mimicry is certain from many considerations, not the least striking of which is that frequently one of the sexes is protectively colored and not the other.
The brilliant coloring of poisonous snakes is sometimes set down by naturalists to "warning," but the details of coloring among reptiles have never been thoroughly worked out. The difficulty suggests itself that if the vivid yellows and oranges of some snakes are meant to warn off dangerous animals, the same conspicuousness would warn off the animals on which the venomous forms prey. Thus, while being hunted, a showy skin might be of advantage to the snake; in hunting it would be an equal disadvantage. But when one watches on the spot the manner in which snakes really do their hunting, it becomes probable that the coloring, vivid and peculiar as it is, in most cases is designed simply to aid concealment. One of the most beautiful and ornate of all the tropical reptiles is the puff-adder. This animal, the bite of which is certain death, is from three to five feet long, and disproportionately thick, being in some parts almost as thick as the lower part of the thigh. The whole body is ornamented with strange devices in green, yellow, and black, and lying in a museum its glittering coils certainly form a most striking object. But in nature the puff-adder has a very different background. It is essentially a forest animal, its true habitat being among the fallen leaves in the deep shade of the trees by the banks of streams. Now in such a position, at the distance of a foot or two, its appearance so exactly resembles the forest bed as to be almost indistinguishable from it. I was once just throwing myself down under a tree to rest when, stooping to clear the spot, I noticed a peculiar pattern among the leaves. I started back in horror to find a puff-adder of the largest size, its thick back only visible, and its fangs within a few inches of my face as I stooped. It was lying concealed among fallen leaves so like itself that, but for the exceptional caution which in African travel becomes a habit, I should certainly have sat down upon it, and to sit down upon a puff-adder is to sit down for the last time. I think this coloration in the puff-adder is more than that of warning, and that this semi-somnolent attitude is not always the mere attitude of repose. This reptile lay lengthwise, concealed all but a few inches, among the withered leaves. Now the peculiarity of the puff-adder is that it strikesbackward. Lying on the ground, therefore, it commands as it were its whole rear, and the moment any part is touched, the head doubles backward with inconceivable swiftness, and the poison-fangs close upon their victim. The puff-adder in this way forms a sort of horrid trap set in the woods which may be altogether unperceived till it shuts with a sudden spring upon its prey.
But that the main function of coloring is protection may be decided from the simplest observation of animal life in any part of the world. Even among the larger animals, which one might suppose independent of subterfuge and whose appearance anywhere but in their native haunts suggests a very opposite theory, the harmony of color with environment is always more or less striking. When we look, for instance, at the coat of a zebra with its thunder-and-lightning pattern of black and white stripes, we should think such a conspicuous object designed to court rather than to elude attention. But the effect in nature is just the opposite. The black and white somehow take away the sense of a solid body altogether; the two colors seem to blend into the most inconspicuous gray, and at close quarters the effect is as of bars of light seen through the branches of shrubs. I have found myself in the forest gazing at what I supposed to be a solitary zebra, its presence betrayed by some motion due to my approach, and suddenly realized that I was surrounded by an entire herd which were all invisible until they moved. The motionlessness of wild game in the field when danger is near is well known; and every hunter is aware of the difficulty of seeing even the largest animals though they are just standing in front of him. The tiger, whose stripes are obviously meant to imitate the reeds of the jungle in which he lurks, is nowhere found in Africa: but its beautiful cousin, the leopard, abounds in these forests, and its spotted pelt probably conveys the same sense of indistinctness as in the case of the zebra. The hippopotamus seems to find the deep water of the rivers—where it spends the greater portion of its time—a sufficient protection; but the crocodile is marvellously concealed by its knotted mud-colored hide, and it is often quite impossible to tell at a distance whether the objects lying along the river banks are alligators or fallen logs.
But by far the most wonderful examples of protective adjustments are found where the further disguise of form is added to that of color, and to this only is the term mimicry strictly applicable. The pitch of intricate perfection to which mimicry has attained in an undisturbed and unglaciated country like Central Africa is so marvellous and incredible, that one almost hesitates to utter what his eyes have seen. Before going to Africa I was of course familiar with the accounts of mimetic insects to be found in the works of Bates, Belt, Wallace, and other naturalists; but no description prepares one in the least for the surprise which awaits him when first he encounters these species in nature. My introduction to them occurred on the borders of Lake Shirwa—one of the smaller and less known of the great African lakes—and I shall record the incident exactly as I find it in my notes. I had stopped one day among some tall dry grass to mark a reading of the aneroid, when one of my men suddenly shouted "Chirombo!" "Chirombo" means an inedible beast of any kind, and I turned round to see where the animal was. The native pointed straight at myself. I could see nothing, but he approached, and pointing close to a wisp of hay which had fallen upon my coat, repeated "Chirombo!" Believing that it must be some insect among the hay, I took it in my fingers, looked over it, and told him pointedly there was no "Chirombo" there. He smiled, and pointing again to the hay, exclaimed "Moio!"—"It's alive!" The hay itself was the Chirombo. I do not exaggerate when I say that that wisp of hay was no more like an insect than my aneroid barometer. I had mentally resolved never to be taken in by any of these mimetic frauds; I was incredulous enough to suspect that the descriptions of Wallace and the others were somewhat highly colored; but I confess to have been completely stultified and beaten by the very first mimetic form I met. It was one of that very remarkable family thePhasmidæ, but surely nowhere else in nature could there be such another creature. Take two inches of dried yellow grass-stalk, such as one might pluck to run through the stem of a pipe; then take six other pieces nearly as long and a quarter as thick; bend each in the middle at any angle you like, stick them in three opposite pairs, and again at any angle you like, upon the first grass stalk, and you have my Chirombo. When you catch him, his limbs are twisted about at every angle, as if the whole were made of one long stalk of the most delicate grass, hinged in a dozen places, and then gently crushed up into a dishevelled heap. Having once assumed a position, by a wonderful instinct he never moves or varies one of his many angles by half a degree. The way this insect keeps up the delusion is indeed almost as wonderful as the mimicry itself; you may turn him about and over and over, but he is mere dried grass, and nothing will induce him to acknowledge the animal kingdom by the faintest suspicion of spontaneous movement. All the members of this family have this power of shamming death; but how such emaciated and juiceless skeletons should ever presume to be alive is the real mystery. These Phasmidæ look more like ghosts than living creatures, and so slim are they that, in trying to kill them for the collecting-box, the strongest squeeze between finger and thumb makes no more impression upon them than it would upon fine steel wire, and one has to half-guillotine them against some hard substance before any little life they have is sacrificed to science.
I examined after this many thousands of Phasmidæ, Mantidæ, and other mimetic forms, and there is certainly in nature no more curious or interesting study. These grass-stalk insects live exclusively among the long grass which occurs in patches all over the forests, and often reaches a height of eight or ten feet. During three-fourths of the year it is dried by the sun into a straw-yellow color, and all the insects are painted to match. Although yellow is the ground tone of these grasses, they are variegated, and especially towards the latter half of the year, in two ways. They are either tinged here and there with red and brown, like the autumn colors at home, or they are streaked and spotted with black mould or other markings, painted by the finger of decay. All these appearances are closely imitated by insects. To complete the deception, some have the antennæ developed to represent blades of grass, which are often from one to two inches in length, and stick out from the end of the body, one on either side, like blades of grass at the end of a stalk. The favorite attitude of these insects is to clasp a grass-stalk, as if they were climbing a pole; then the body is compressed against the stem and held in position by the two fore-limbs, which are extended in front so as to form one long line with the body, and so mixed up with the stalk as to be practically part of it. The four other legs stand out anyhow in rigid spikes, like forks from the grass, while the antennæ are erected at the top, like blades coming off from a node, which the button-like head so well resembles. When one of these insects springs to a new stalk of grass it will at once all but vanish before your eyes. It remains there perfectly rigid, a component part of the grass itself, its long legs crooked and branched exactly like dried hay, the same in color, the same in fineness, and quite defying detection. These blades, alike with limbs and body, are variously colored according to season and habitat. When the grasses are tinged with autumn tints they are the same; and the colors run through many shades, from the pure bright red, such as tips the fins of a perch, to the deeper claret colors or the tawny gold of port. But an even more singular fact remains to be noted. After the rainy season, when the new grasses spring up with their vivid color, these withered-grass insects seem all to disappear. Their color now would be no protection to them, and their places are taken by others colored as green as the new grass. Whether these are new insects or only the same in spring toilets I do not know; but I should think they are a different population altogether, the cycle of the former generation being, probably, complete with the end of summer.
Besides the insects which imitate grass, another large class imitate twigs, sticks, and the smaller branches of shrubs. The commonest of these is a walking twig, three or four inches long, covered with bark apparently, and spotted all over with mould like the genuine branch. The imitation of bark here is one of the most perfect delusions in nature; the delicate striation and the mould spots are reproduced exactly, while the segmentation of the body represents node-intervals with wonderful accuracy. On finding one of these insects I have often cut a small branch from an adjoining tree and laid the two side by side for comparison; and when both are partly concealed by the hands so as to show only the part of the insect's body which is free from limbs, it is impossible to tell the one from the other. The very joints of the legs in these forms are knobbed to represent nodes, and the characteristic attitudes of the insect are all such as to sustain the deception.
A still more elaborate set of forms are those which represent leaves. These belong mostly to the Mantis and Locust tribes, and they are found in all forms, sizes, and colors, mimicking foliage at every stage of growth, maturity and decay. Some have the leaf stamped on their broadened wing-cases in vivid green, with veins and midrib complete, and with curious expansions over the thorax and along all the limbs to imitate smaller leaves. I have again and again matched these forms in the forest, not only with the living leaf, but with crumpled, discolored, and shrivelled specimens, and indeed the imitations of the crumpled autumn-leaf are even more numerous and impressive than those of the living form. Lichens, mosses, and fungi are also constantly taken as models by insects, and there is probably nothing in the vegetal kingdom, no knot, wart, nut, mould, scale, bract, thorn, or bark, which has not its living counterpart in some animal form. Most of the moths, beetles, weevils, and especially the larval forms, are more or less protected mimetically; and in fact almost the entire population of the tropics is guilty of personation in ways known or unknown. The lichen-mimicking insects even go the length of imitating holes, by means of mirror-like pools of black irregularly disposed on the back, or interrupting the otherwise dangerous symmetry of the fringed sides. The philosophy of these coal-black markings greatly puzzled me for a time. The first I saw was on a specimen of the singular and rareHarpax ocellaria, which had been thrown on the camp fire clinging to a lichen-covered log, and so well carried out was the illusion that even the natives were deceived till the culprit betrayed its quality by erecting its gauzy wings.
But it would be tedious to recount further the divisive ways of these arch-deceivers, and I shall only refer to another mimetic form, which for cool Pharisaism takes the palm from every creeping or flying thing. I first saw thismenteur à triple ètayeon the Tanganyika plateau. I had lain for a whole week without stirring from one spot—a boulder in the dried-up bed of a stream, for this is the only way to find out what really goes on in nature. A canopy of leaves arched overhead, the home of many birds, and the granite boulders of the dry stream-bed, and all along the banks, were marked with their white droppings. One day I was startled to see one of these droppings move. It was a mere white splash upon the stone, and when I approached I saw I must be mistaken; the thing was impossible; and now it was perfectly motionless. But I certainly saw it move, so I bent down and touched it. It was an animal. Of course it was as dead as a stone the moment I touched it, but one soon knows these impostures, and I gave it a minute or two to become alive—hastily sketching it meantime in case it should vanish through the stone, for in that land of wonders one really never knows what will happen next. Here was a bird-dropping suddenly become alive and moving over a rock; and now it was a bird-dropping again; and yet, like Galileo, I protest that it moved. It would not come to, and I almost feared I might be mistaken after all, so I turned it over on its other side. Now should any sceptic persist that this was a bird-dropping I leave him to account for a bird-dropping with six legs, a head, and a segmented body. Righting the creature, which showed no sign of life through all this ordeal, I withdrew a few paces and watched developments. It lay motionless on the stone, no legs, no head, no feelers, nothing to be seen but a flat patch of white—just such a patch as you could make on the stone in a second with a piece of chalk. Presently it stirred, and the spot slowly sidled across the boulder until I caught the impostor and imprisoned him for my cabinet. I saw in all about a dozen of these insects after this. They are about half the size of a fourpenny-piece, slightly more oval than round, and as white as a snowflake. This whiteness is due to a number of little tufts of delicate down growing out from minute protuberances all over the back. It is a fringe of similar tufts round the side that gives the irregular margin so suggestive of a splash; and the under surface of the body has no protection at all. The limbs are mere threads, and the motion of the insect is slow and monotonous, with frequent pauses to impress surrounding nature with its moribund condition. Now, unless this insect with this color and habit were protectively colored it simply would not have a chance to exist. It lies fearlessly exposed on the bare stones during the brightest hours of the tropical day, a time when almost every other animal is skulking out of sight. Lying upon all the stones round about are the genuine droppings of birds; and when one sees the two together it is difficult to say whether one is most struck with the originality of the idea, or the extraordinary audacity with which therôleis carried out.*
* It is a considerable responsibility to be the sole witness to this comedy—though I saw it repeated a dozen times subsequently—but, fortunately for my veracity, I have since learned from Mr. Kirby of the British Museum that, there is an English beetle, theCionus Blattaria, the larval form of which "operates" in a precisely similar way.
It will be apparent from these brief notes that mimicry is not merely an occasional or exceptional phenomenon, but an integral part of the economy of nature. It is not a chance relation between a few objects, but a system so widely authorized that probably the whole animal kingdom is more or less involved in it; a system, moreover, which, in the hands of natural selection, must ever increase in intricacy and beauty. It may also be taken for granted that a scheme so widespread and so successful is based upon some sound utilitarian principle. That principle, I should say, was probably itseconomy. Nature does everything as simply as possible, and with the least expenditure of material. Now consider the enormous saving of muscle and nerve, of instinct and energy, secured by making an animal's lease of life to depend on passivity rather than activity. Instead of having to run away, the creature has simply to keep still; instead of having to fight, it has but to hide. No armor is needed, no powerful muscle, no expanse of wing. A few daubs of color, a little modelling of thorax and abdomen, a deft turn of antennæ and limb, and the thing is done.
At the first revelation of all these smart hypocrisies one is inclined to brand the whole system as cowardly and false. And, however much the creatures impress you by their cleverness, you never quite get over the feeling that there is something underhand about it; something questionable and morally unsound. The evolutionist, also, is apt to charge mimetic species in general with neglecting the harmonious development of their physical framework, and by a cheap and ignoble subterfuge evading the appointed struggle for life. But is it so? Are the æsthetic elements in nature so far below the mechanical? Are color and form, quietness and rest, so much less important than the specialization of single function or excellence in the arts of war? Is it nothing that, while in some animals the disguises tend to become more and more perfect, the faculties for penetrating them, in other animals, must continually increase in subtlety and power? And, after all, if the least must be said, is it not better to be a live dog than a dead lion?
From the work of the various explorers who have penetrated Africa, it is now certain that the interior of that Continent is occupied by a vast plateau from 4000 to 5000 feet above the level of the sea. In five separate regions—in the North-east, in Abyssinia, in the Masai country, on the Tanganyika plateau, and in the district inland from Benguela—this plateau attains a height of considerably over 5000 feet; while towards the coast, throughout their entire length, both east and west, it falls with great uniformity to a lower plateau, with an elevation of from 1000 to 2000 feet. This lower plateau is succeeded, also with much uniformity along both coast lines, by littoral and deltoid plains, with an average breadth from the sea of about 150 miles.
The section which I am about to describe, entering Africa at the Zambesi and penetrating inwards to the Tanganyika plateau, traverses each of these regions in turn—the coast-belt, the lower fringing table-land, the great general plateau of the country, and the third or highest elevation of the Tanganyika table-land. To deal thoroughly with so vast a region in the course of a single exploration is out of the question; and I only indicate here a few of the rough results of what was no more than a brief and hasty reconnaissance.
The first and only geological feature to break the monotony of mangrove-swamp and low grass plain of the coast-belt is the debris of an ancient coral-reef, studded with sponges and other organisms. This reef is exposed on the Qua-qua River, a little above Mogurrumba, and about fifty miles from the sea. It is of small extent, at no great height above the present sea-level, and, taken alone, can only argue for a very inconsiderable elevation of the coast region. Some twenty miles farther inland, and still only a few yards above sea-level, an inconspicuous elevation appears, consisting of sedimentary rocks. This belt is traceable for some distance, both north and south, and a poor section may be found in the Zambesi River, a few miles above the grave of Mrs. Livingstone at Shupanga. The rocks in question, which are only visible when the Zambesi is very low, consist of a few thin beds of red and yellow sandstones, with intercalated marly sandstones and fine conglomerates. Sedimentary rocks, in somewhat similar relation, are found at least as far north as Mombassa, above Zanzibar, and as far south as the Cape; and it seems probable that the whole of the plateau of the interior is fringed by this narrow belt. No organic remains have been found in this series north of Natal, but the fossils of the Cape beds may shed some light on its horizon. Associated probably with these rocks are the great beds of coal which are known to exist some distance up the river in the neighborhood of Tette.
A short distance above the junction of the River Shiré with the Zambesi the first hills of the plateau begin almost abruptly. They occur in irregular isolated masses, mostly of the saddle-back order, and varying in height from 100 or 200 to 2000 feet. Those I examined consisted entirely of a very white quartzite—the only quartzite, I may say, I ever saw in East Central Africa. At the foot of the most prominent of those hills—that of Morumballa—a hot-spring bubbles up, which Livingstone has already described in his "Zambesi." Hot-springs are not uncommon in other parts of the Continent, and several are to be found on the shores of Lake Nyassa. These are all of the simplest type, and although the temperature is high they leave no deposit anywhere to indicate their chemical character.
Two or three days' journey north and west of Morumballa, among the distant hills which border the valley of the Shiré, Livingstone marks a spot in his sketch-map where coal is to be found. After examining the neighborhood with some care, and cross-examining the native tribes, I conclude that Livingstone must, in this instance, have been either mistaken or misinformed. A black rock certainly occurs at the locality named, but after securing specimens of this as well as of all the dark-colored rocks in the vicinity, I found them to be, without exception, members of the igneous class. One very dark diorite was probably the rock which, on a distant view, had been mistaken for coal, for none of the natives along the whole length of the lower Shiré had ever heard of "a black rock which burned." Coal, however, as already mentioned, does certainly occur farther inland on the Zambesi; while, farther south, the Natal and Transvaal coalfields are now well known.
While speaking of coal I may best refer here to a small coal-bed associated with an apparently different series of rocks, and of special interest from its occurrence in the far interior of the country. On the western shore of Lake Nyassa, about 10° south latitude, coal was reported a few years ago by a solitary explorer, who penetrated that region prospecting for gold in the wake of Livingstone. The importance of such a discovery—a coal-seam on the borders of one of the great inland seas of Africa—cannot be over-estimated; and the late Mr. James Stewart, C.E., who has done such important work for the geography of Africa, made a special examination of the spot. From his report to the Royal Geographical Society I extract the following reference:—
"On the 29th we marched northwards along the coast, reaching, after three miles, the stream in which is the coal discovered by Mr. Rhodes. The coal lies in a clay bank, tilted up at an angle of 45°, dip west. It is laid bare over only some 30 feet, and is about 7 feet thick. It hardly looks as if it were in its original bed. The coal is broken and thrown about as if it had been brought down by a landslip, and traces of clay are found in the interstices. Yet the bed is compact, and full of good coal. I traced it along the hillside for some 200 yards, and found it cropping out on the surface here and there. It is 500 feet above the lake-level, and about a mile and a half from the shore. I lit a good fire with it, which burned up strongly. The coal softened and threw out gas bubbles, but gave no gas-jets. It caked slightly, but not so as to impede its burning."—Proceedings, vol. iii. No. 5, p. 264.
I examined this section pretty carefully, and fear I must differ slightly from Mr. Stewart in his geological and economical view of the formation. The 7-foot seam described by Stewart is certainly a deception, the seam being really composed of a series of thin beds of alternately carbonaceous and argillaceous matter, few of the layers of coal being more than an inch in thickness. With some of the most carefully selected specimens I lit a fire, but with disappointing results. Combustion was slow, and without flame. Although there were what can only be calledfilmsof really good coal here and there, the mineral, on the whole, seemed of inferior quality, and useless as a steam-coal. From the general indications of the locality I should judge that the coal existed only in limited quantity, while the position of the bed at the top of a rocky gorge renders the deposit all but inaccessible. On the whole, therefore, the Lake Nyassa coal, so far as opened up at present, can scarcely be regarded as having any great economical importance, although the geological interest of such a mineral in this region is considerable. Sections of the coal have already been prepared for the microscope, and Dr. Carruthers of the British Museum has identified the macrospores of Lycopodaceous plants, which are identical with similar organisms found in the coal-fields of England.
The Geology of the great African plateaux, so far as my section from the Lower Shiré to the Tanganyika plateau is any indication of their general structure, is of such simplicity that it may almost be dismissed in a sentence. The whole country from the Shiré river, a hundred miles above its junction with the Zambesi, embracing the lower and higher central plateaux, the whole Shiré Highlands from the river to the westward shores of Lake Shirwa, the three hundred miles of rocky coast fringing the western shore of Lake Nyassa, the plateau between Nyassa and Tanganyika for at least half its length—with one unimportant interruption—consists solely of granite and gneiss. The character and texture of this rock persist with remarkable uniformity throughout this immense region. The granite, an ordinary gray granite, composed of white rarely pink orthoclase felspar, the mica of the biotitic or magnesian variety, rarely muscovite, and neither fine nor coarse in texture; the gneiss, the same rock foliated. Of the relation of these gneissose and granitic rocks to one another I was unable to discover any law. Sometimes the gneiss would persist over a large area, sometimes the granite; while frequently the two would alternate perplexingly within a limited area. Mr. Joseph Thomson's section, drawn inland from Zanzibar and joining mine at the northern end of Lake Nyassa, and thence onwards by a more easterly route towards Tanganyika, reveals a somewhat similar petrographical structure; and, from scattered references in the journals of other explorers, it is plain that this gneisso-granitic formation occupies a very large area in the interior of the African Continent. Associated minerals with these rocks, as far as a very general survey indicated, were all but wholly wanting. At Zomba, on the Shiré Highlands, a little tourmaline occurs, but of the precious metals I could find no trace. Veins of any kind are also rare; and even pegmatite I encountered in only one instance. Intrusive dykes throughout the whole area were like-wise absent except in a single district. This district lies towards the southern border of the Shiré Highlands, immediately where the plateau rises from the river, and there the dykes occur pretty numerously. They are seldom more than a few feet in breadth, and consist of ordinary dolerite or basalt. The black rock on the Lower Shiré, already mentioned in connection with Livingstone's supposed discovery of coal, may possibly be one of these dykes; but that there is any considerable development of igneous rocks in this immediate locality I should doubt. Farther up the Zambesi, however, coulees of basalt are met with at more than one place, conspicuously in the neighborhood of the Victoria Falls. The only distinct trace of volcanic action throughout my route appeared towards the extreme northern end of Lake Nyassa. One is warned beforehand by occasional specimens of pumice lying about the lake shore as one travels north; but it is not till the extreme end of the lake is reached that the source is discovered in the series of low volcanic cones which Thomson has already described in this locality. The development is apparently local, and the origin of the cones probably comparatively recent.
Apart from this local development of igneous rocks at the north end of Lake Nyassa, the only other break in the granitic series throughout the area traversed by my line of march occurs near the native village of Karonga, on Lake Nyassa. About a dozen miles from the north-western lake shore on the route to Tanganyika, after following the Rukuru river through a defile of granite rocks, I came, to my great surprise, upon a well-marked series of stratified beds. At a bend in the river a fine section is exposed. They lie throw against the granitic rocks, which here show signs of disturbance, and consist of thin beds of very fine light-gray sandstone, and blue and gray shales, with an occasional band of gray limestone. By camping at the spot for some days, and working patiently, I was rewarded with the discovery of fossils. This is, of course, the main interest of these beds,—for these are, I believe, the only fossils that have ever been found in Central Africa. The shale, naturally, yielded the most productive results, one layer especially being one mass of smallLamellibranchiata. Though so numerous, these fossils are confined to a single species of theTellinidæ, a family abundantly represented in tropical seas at the present time, and dating back as far as the Oolite. Vegetable remains are feebly represented by a few reeds and grasses. Fish-scales abound; but I was only able, and that after much labor, to unearth two two or three imperfect specimens of the fishes themselves. These have been put into the accomplished hands of Dr. Traquair of Edinburgh, who has been kind enough to furnish the following account of them:—
EDINBURGH, 23d April, 1888.
DEAR PROFESSOR DRUMMOND—I have carefully examined the six specimens of fossil fish-remains from Central Africa, which you submitted to me, and though I certainly would have wished them to have been less fragmentary, I shall do my best to give an opinion upon them.
No. 1, the largest, is the hinder portion of a fish of moderate size, showing not only scales, but also the remains of the dorsal, anal, and caudal fins. The caudal is strongly heterocercal, and was probably deeply bifurcated, but the rays of the lower lobe are very badly preserved: only the posterior parts of the dorsal and anal are seen, nearly opposite each other, and composed of fine, closely placed, and closely articulated rays. The scales, displaced and jumbled up, are osseous, thick, and rhomboidal, with a strong blunt carina on the attached surface, while the exposed part of the external surface is covered with ganoine, and ornamented with rather sparsely scattered pits and punctures.
Belonging to the Order Ganoidei, this fish is with equal certainty referable to the family Palæoniscidæ, but itsgenusis more a matter of doubt owing to the fragmentary nature of the specimen. Judging from the form and thickness of the scales, I should be inclined to refer it toAcrolepis, were it not that the dorsal and anal fins seem so close to the tail, and so nearly opposite each other; here, however, it may be remarked that the disturbed state of the scales affords room for the possibility that the original relations of the parts may not be perfectly preserved. I have, however, no doubt that, as aspecies, it is new; and as you have been the first to bring fossil fishes from those regions of Central Africa, you will perhaps allow me to name itAcrolepis(?)Drummondi.
No. 2 is a piece of cream-colored limestone, with numerous minute, scattered, rhombic, striated, ganoid scales, which I cannot venture to name, though I believe them to be palæoniscid. Associated with these is a small portion of the margin of a jaw, with numerous minute sharp conical teeth. But also lying among these minuter relics is a scale of a much larger size, and clearly belonging to another fish. It measures 1-4 inch in height by the same in breadth; its shape is rhomboidal, having an extensive anterior covered area, and a strong articular spine projecting from the upper margin. The free surface is brilliantly ganoid, and marked with furrows separating feeble ridges, which pass rather obliquely downwards and backwards across the scale, and terminate in eight sharp denticulations of the hinder margin. A little way off is the impression of the attached surface of a similar scale, and there are also two interspinous bones, probably belonging to the same fish.
This is probably also a palæoniscid scale, resembling in shape those ofAcrolepis, but it is rather thinner than is usually the case in this genus. It has also considerable resemblance to some of those scales from the European Trias, named by AgassizGyrolepis. Though it may be rather venturesome to name a species from such slender material, nevertheless we may, provisionally at least, recognize the scale asAcrolepis (?) Africanus.
Nos. 3 and 4 are small pieces of the same limestone, covered with the minute striated palæoniscid scales referred to above.
No. 5 is a piece of gray micaceous shale, with scales of yet a fourth species of palæoniscid fish. One conspicuous scale unfortunately, like all the rest, seen only from the attached surface, is 1-4 inch in height by nearly 1-6 in breadth; it is tolerably rectangular in shape, having a well-developed articular spine and fossette. Part of the scale is broken away at the anterior margin, the impression brought into view showing that the covered area is narrow, and indicating that the free surface is striated with rather sharp ridges passing obliquely across the scale. The posterior margin is finely denticulated.
Though this scale is in my opinion specifically, and possibly generically, distinct from those previously named, the outer surface not being properly displayed renders it impossible to give a sufficient diagnosis.
No. 6 is a piece of the same shale, having the clavicle of a small palaeoniscid fish, which it is, however, impossible to name.—I am, yours faithfully,
R. H. TRAQUAIR.
These fossiliferous beds seem to occupy a comparatively limited area, and have a very high dip in a south-easterly direction. At the spot where my observations were taken they did not extend over more than half a mile of country, but it is possible that the formation may persist for a long distance in other directions. Indeed, I traced it for some miles in the direction in which, some fifty or sixty miles off, lay the coal already described, and to which it may possibly be related.
With one or two general remarks upon surface geology and physical geography I bring this note to a close. First, regarding the Lakes Nyassa and Shirwa,—there is distinct evidence, and especially in the case of the latter, that they have formerly occupied a considerably larger area than at present. Shirwa is an extremely shallow lake; though the eastern and southern shores are mountainous, it is suggestive rather of an immense bog than of a deep inland sea. For many miles before reaching the shore there are signs that one is traversing the site of a former and larger Shirwa, which may possibly at one time have been actually connected with the lower extremity of Lake Nyassa. To substantiate this conclusion, however, will require more detailed examination of the Shiré Highlands than I was able to give. The peculiarity of Shirwa is that the water is brackish to the taste, while that of Nyassa and of the other Central African lakes, with the exception of Lake Leopold, is fresh. The shallowness of Shirwa, and the precariousness of its outlet through Lake Cheuta to the Lujenda, amply account for this difference; for the narrow waters of Nyassa and Tanganyika are thoroughly drained and profoundly deep.
That Lake Nyassa is also slowly drying up is evident from the most superficial examination of its southern end. There it has already left behind a smaller lake—Lake Pomalombé—a considerable expanse of water, through which the Shiré passes a few miles after emerging from Lake Nyassa, but already so shallow that nowhere in the dry season does the depth exceed three fathoms. If the silting up of this lake continues for a few years it will render this sheet of water, which commands the entrance to Lake Nyassa, totally unnavigable, and thus close the magnificent water-highway at present open, with a portage of seventy miles, from the top of Lake Nyassa to the Indian Ocean at the mouth of the Zambesi.
Regarding the interesting question of the origin of Lake Nyassa and its great sister-lakes in the heart of Africa—the Victoria and Albert Nyanza and Tanganyika—I do not presume to speak. No follower of Ramsay in his theory of the glacial origin of lakes could desire a more perfect example of a rock-basin than that of Lake Nyassa. It is a gigantic trough of granite and gneiss, three hundred miles in length, nowhere over fifty miles in breadth, and sixteen hundred feet above the level of the sea, the mountains rising all around it, and sometimes almost sheer above it, to a farther height of one, two, and three thousand feet. The high Tanganyika plateau borders it on the northern shore, and the greatest depth is precisely where the glacial theory would demand, namely, towards the upper portion of the lake. On the other hand, the physical geology of the country in which these other lakes are situated, as well as several features connected with Lake Nyassa itself, lend no countenance to such a view; and probably the suggestion of Murchison and other geologists is correct, that all these lakes, colossal though they still are, are the remnants of a much vaster expanse of water which once stretched over Central Africa.
The only other point to which I need allude is the subject of glaciation itself. And I refer to this pointedly, because I have lately encountered allusions, and in quarters entitling them to respect, to the presence of glacial phenomena in the Central Lake district of Africa. I confess that my observations have failed to confirm these suggestions. It has been my lot to have had perhaps exceptional opportunities of studying the phenomena of glaciation in Europe and Northern America, and I have been unable to detect anywhere in the interior of Africa a solitary indication of glacial action. In Kaffirland, far to the south, there are features which one would almost unhesitatingly refer to glaciation; but in East Central Africa not a vestige of boulder-clay, nor moraine matter, nor striæ, nor glaciated surface, nor outline, is anywhere traceable. One would be curious to know to what extent the flora and fauna of the inland plateau confirm or contradict this negative evidence against the glaciation of this region.
Finally, the thing about the geology of Africa that strikes one as especially significant is that throughout this vast area, just opening up to science, there is nothing new—no unknown force at work; no rock strange to the petrographer; no pause in denudation; no formation, texture, or structure to put the law of continuity to confusion. Rapid radiation, certainly, replaces the effects of frost in northern lands—and the enormous denudation due to this cause is a most striking feature of tropical geology. The labors of the worm, again, in transporting soil in temperate climates are undertaken by the termite; but here, as elsewhere, every fresh investigation tends to establish more and more the oneness and simplicity of Nature.
When I reached the coast to embark for England after my wanderings in the interior, the Portuguese authorities at Quilimane presented me with various official documents, which I was told I must acknowledge with signatures and money before being permitted to leave Africa. Having already had to pay certain moneys to Portugal to get into this country, it was a shock to find that I had also to pay to get out; but, as no tax could be considered excessive that would facilitate one's leaving even the least of the Portuguese East African colonies, I cheerfully counted out the price of my release. Before completing the conveyance, however, my eye fell on six words prominently endorsed on one of the documents, which instantly tightened my purse-strings. The words were, "TAX FOR RESIDING IN THE INTERIOR"—so much. Now a day or two spent in waiting for a steamer could scarcely be construed into residence, nor could a strip of coast-line with propriety be termed the interior, so I ventured to point out the irrelevancy to the Portuguese official. Waiving the merely philological question of residence, he went at once to the root of the matter by informing me that the Portuguese definition of the word Interior differed materially from that of England. The Interior, he said, comprised the whole of Africa inland from the coast-province of Mozambique, and included, among other and larger possessions, the trifling territories of the Upper Shiré Highlands, Lake Shirwa, and Lake Nyassa. These last, he assured me, belonged to Portugal, and it became me, having therein shared the protection of that ancient flag, to acknowledge the obligation to the extent of so many hundred Reis.
Though not unprepared for this assumption, the idea of enforcing it by demanding tribute was so great a novelty that, before discharging my supposed liabilities, I humbly asked information on the following points:—1. Did the region described really belong to Portugal? 2. When and where was this claim recognized by England directly or indirectly? 3. Where in the Interior, as thus defined, was the Portuguese flag to be found? And 4. What protection had it ever given to me or to any other European? The replies to these queries being evasive, I took it upon myself to correct the history, the geography, and the politics of the throng of Government officials who now joined the sederunt by the following statement of facts:—1. The region described did not belong to Portugal. 2. Its sovereignty had never been in any way acknowledged by England. 3. The Portuguese flag was nowhere to be found there, and never had been there. 4. Not one solitary Portuguese up to that time had ever even set foot in the country—except one man who was brought in for a few weeks under English auspices; so that no protection had ever been given, or could possibly be given, to me or to any one else. These statements were received in silence, and after much running to and fro among the officials the representative of John Bull, instead of being dragged to prison, and his rifle—his only real escort through Nyassa-land—poinded to pay for his imaginary protection, found himself bowed off the premises with a discharge in full of his debt to Portugal, and the unpaid tax-paper still in his pocket.
I recall this incident to introduce in all seriousness the question interesting so many at the present moment as to the title-deeds of Equatorial Africa. Why Africa should not belong to the Africans I have never quite been able to see, but since this Continent is being rapidly partitioned out among the various European States, it is well, even in the African interest, to inquire into the nature and validity of these claims. The two political maps which will be found at the end of this volume will enable those interested to see the present situation at a glance, and I shall only further emphasize one or two points of immediate practical importance.
[Transcriber's note: The two maps mentioned above were missing from the source book.]
The connection of Portugal with Africa is an old, and—at least it was at first—an honorable one. The voyages of the Portuguese were the first to enrich geography with a knowledge of the African coasts, and so early as 1497 they took possession of the eastern shore by founding the colony of Mozambique. This rule, however, though nominally extending from Delagoa Bay to as far north as Cape Delgado, was confined to two or three isolated points, and nowhere, except on the Zambesi, affected more than the mere fringe of land bordering the Indian Ocean. On the Zambesi the Portuguese established stations at Senna, Tette, and Zumbo, which were used, though on the most limited scale, as missionary and trading centres; but these are at present all but abandoned and in the last stages of decrepitude. The right of Portugal to the lower regions of the Zambesi, notwithstanding its entire failure to colonize in and govern the country, can never be disputed by any European Power, though the Landeens, or Zulus, who occupy the southern bank, not only refuse to acknowledge the claim, but exact an annual tribute from the Portuguese for their occupation of the district.
No one has ever attempted to define how far inland the Portuguese claim, founded on coast-possession, is to be considered good; but that it cannot include the regions north of the Zambesi—the Shiré Highlands and Lake Nyassa—is self-evident. These regions were discovered and explored by Livingstone. They have been occupied since his time exclusively by British subjects, and colonized exclusively with British capital. The claim of England, therefore—though nothing but a moral claim has ever been made—is founded on the double right of discovery and occupation; and if it were a question of treaty with the natives, it might possibly be found on private inquiry that a precaution so obvious had not been forgotten by those most nearly interested. On the other hand, no treaties exist with Portugal; there is not a single Portuguese in the country, and until the other day no Portuguese had even seen it. The Portuguese boundary-line has always stopped at the confluence with the Shiré of the river Ruo, and the political barrier erected there by Chipitula and the river Chiefs has been maintained so rigidly that no subject of Portugal was ever allowed to pass it from the south. Instead, therefore, of possessing the Shiré Highlands, that is the region of all others from which the Portuguese have been most carefully excluded.
The reason for this enforced exclusion is not far to seek. At first the Portuguese had too much to do in keeping their always precarious foothold on the banks of the Zambesi to think of the country that lay beyond; and when their eyes were at last turned towards it by the successes of the English, the detestation in which they were by this time held by the natives—the inevitable result of long years of tyranny and mismanagement—made it impossible for them to extend an influence which was known to be disastrous to every native right. Had the Portuguese done well by the piece of Africa of which they already assumed the stewardship, no one now would dispute their claim to as much of the country as they could wisely use. But when even the natives have had to rise and by force of arms prevent their expansion, it is impossible that they should be allowed to overflow into the Highland country—much less to claim it—now that England, by pacific colonization and missionary work, holds the key to the hearts and hands of its peoples. By every moral consideration the Portuguese have themselves forfeited the permission to trespass farther in Equatorial Africa. They have done nothing for the people since the day they set foot in it. They have never discouraged, but rather connived at, the slave-trade; Livingstone himself took the servant of the Governor of Tette red-handed at the head of a large slave-gang. They have been at perpetual feud with the native tribes. They have taught them to drink. Their missions have failed. Their colonization is not even a name. With such a record in the past, no pressure surely can be required to make the Government of England stand firm in its repudiation of a claim which, were it acknowledged, would destroy the last hope for East Central Africa.
England's stake in this country is immeasurably greater than any statistics can represent, but a rough estimate of the tangible English interest will show the necessity of the British Government doing its utmost at least to conserve what is already there.
The Established Church of Scotland has three ordained missionaries in the Shiré Highlands, one medical man, a male and a female teacher, a carpenter, a gardener, and other European and many native agents. The Free Church of Scotland on Lake Nyassa has four ordained missionaries—three of whom are doctors—several teachers and artizans, and many native catechists. The Universities Mission possesses a steamer on Lake Nyassa, and several missionary agents; while the African Lakes Company, as already mentioned, has steamers both on the Shiré and Lake Nyassa, with twelve trading stations established at intervals throughout the country, and manned by twenty-five European agents. All these various agencies, and that of the brothers Buchanan at Zomba, are well equipped with buildings, implements, roads, plantations, and gardens; and the whole represents a capital expenditure of not less than £180,000. The well-known editor of Livingstone's Journals, the Rev. Horace Waller, thus sums up his account of these English enterprises in hisTitle-Deeds to Nyassa-Land: "Dotted here and there, from the mangrove swamps at the Kongoné mouth of the Zambesi to the farthest extremity of Lake Nyassa, we pass the graves of naval officers, of brave ladies, of a missionary bishop, of clergymen, Foreign Office representatives, doctors, scientific men, engineers, and mechanics. All these were our countrymen: they lie in glorious graves; their careers have been foundation-stones, and already the edifice rises. British mission stations are working at high pressure on the Shiré Highlands, and under various auspices, not only upon the shores of Lake Nyassa, but on its islands also, and, by desperate choice as it were, in the towns of the devastating hordes who live on the plateaux on either side of the lake. Numbers of native Christians owe their knowledge of the common faith to these efforts; scores of future chiefs are being instructed in the schools, spread over hundreds of miles; plantations are being mapped out; commerce is developing by sure and steady steps; a vigorous company is showing to tribes and nations that there are more valuable commodities in their land than their sons and daughters." This is the vision which Livingstone saw, when, in the last years of his life, he pleaded with his fellow-countrymen to follow him into Africa. "I have opened the door," he said, "I leave it to you to see that no one closes it after me."