Bramble-Bees and Others Part 11

The Megachiles affirm the exact opposite. They tell me that the animal, though invariable in the essence of its art, is capable of innovation in the details; but at the same time they a.s.sure me that any such innovation is sudden and not gradual. Nothing prepares the innovations, nothing improves them or hands them down; otherwise a selection would long ago have been made amid the diversity of foliage; and the shrub recognized as the most serviceable, especially when it is also plentiful, would alone supply all the building-materials needed. If heredity transmitted industrial discoveries, a Megachile who thought of cutting her disks out of pomegranate-leaves and found them satisfactory ought to have instilled a liking for similar materials into her descendants; and we should this day find Leaf-cutters faithful to the pomegranate-leaves, workers who remained exclusive in their choice of the raw material. The facts refute these theories.

People also say:

'Grant us a variation, however small, in the insect's industry; and that variation, accentuated more and more, will produce a new race and finally a fixed species.'

This trifling variation is the fulcrum for which Archimedes clamoured in order to lift the world with his system of levers. The Megachiles offer us one and a very great one: the indefinite variation of their materials. What will the theorists' levers lift with this fulcrum? Why, nothing at all! Whether they cut the delicate petals of the geranium or the tough leaves of the lilac-bushes, the Leaf-cutters are and will be what they were. This is what we learn from the persistence of each species in its structural details, despite the great variety of the foliage employed.

CHAPTER 9. THE COTTON-BEES.

The evidence of the Leaf-cutters proves that a certain lat.i.tude is left to the insect in its choice of materials for the nest; and this is confirmed by the testimony of the Anthidia, the cotton-manufacturers.

My district possesses five: A. Florentinum, LATR., A. diadema, LATR., A.

manicatum, LATR., A. cingulatum, LATR., A. scapulare, LATR. None of them creates the refuge in which the cotton goods are manufactured. Like the Osmiae and the Leaf-cutters, they are homeless vagrants, adopting, each to her own taste, such shelter as the work of others affords. The Scapular Anthidium is loyal to the dry bramble, deprived of its pith and turned into a hollow tube by the industry of various mining Bees, among which figure, in the front rank, the Ceratinae, dwarf rivals of the Xylocopa, or Carpenter-bee, that mighty driller of rotten wood.

The s.p.a.cious galleries of the Masked Anthophora suit the Florentine Anthidium, the foremost member of the genus so far as size is concerned.

The Diadem Anthidium considers that she has done very well if she inherits the vestibule of the Hairy-footed Anthophora, or even the ordinary burrow of the Earth-worm. Failing anything better, she may establish herself in the dilapidated dome of the Mason-bee of the Pebbles. The Manicate Anthidium shares her tastes. I have surprised the Girdled Anthidium cohabiting with a Bembex-wasp. The two occupants of the cave dug in the sand, the owner and the stranger, were living in peace, both intent upon their business. Her usual habitation is some hole or other in the crevices of a ruined wall. To these refuges, the work of others, we can add the stumps of reeds, which are as popular with the various cotton-gatherers as with the Osmiae; and, after we have mentioned a few most unexpected retreats, such as the sheath provided by a hollow brick or the labyrinth furnished by the lock of a gate, we shall have almost exhausted the list of domiciles.

Like the Osmiae and the Leaf-cutters, the Anthidium shows an urgent need of a ready-made home. She never houses herself at her own expense. Can we discover the reason? Let us first consult a few hard workers who are artificers of their own dwellings. The Anthophora digs corridors and cells in the road-side banks hardened by the sun; she does not erect, she excavates; she does not build, she clears. Toiling away with her mandibles, atom by atom, she manages to contrive the pa.s.sages and chambers necessary for her eggs; and a huge business it is. She has, in addition, to polish and glaze the rough sides of her tunnels. What would happen if, after obtaining a home by dint of long-continued toil, she had next to line it with wadding, to gather the fibrous down from cottony plants and to felt it into bags suitable for the honey-paste?

The hard-working Bee would not be equal to producing all these refinements. Her mining calls for too great an expenditure of time and strength to leave her the leisure for luxurious furnis.h.i.+ng. Chambers and corridors, therefore, will remain bare.

The Carpenter-bee gives us the same answer. When with her joiner's wimble she has patiently bored the beam to a depth of nine inches, would she be able to cut out and place in position the thousand and one pieces which the Silky Leaf-cutter employs for her nest? Time would fail her, even as it would fail a Megachile who, lacking the Capricorn's chamber, had herself to dig a home in the trunk of the oak. Therefore the Carpenter-bee, after the tedious work of boring, gets the installation done in the most summary fas.h.i.+on, simply running up a sawdust part.i.tion.

The two things, the laborious business of obtaining a lodging and the artistic work of furnis.h.i.+ng, seem unable to go together. With the insect as with man, he who builds the house does not furnish it, he who furnishes it does not build it. To each his share, because of lack of time. Division of labour, the mother of the arts, makes the workman excel in his department; one man for the whole work would mean stagnation, the worker never getting beyond his first crude attempts.

Animal industry is a little like our own: it does not attain its perfection save with the aid of obscure toilers, who, without knowing it, prepare the final masterpiece. I see no other reason for this need of a gratuitous lodging for the Megachile's leafy basket or the Anthidia's cotton purses. In the case of other artists who handle delicate things that require protection, I do not hesitate to a.s.sume the existence of a ready-made home. Thus Reaumur tells us of the Upholsterer-bee, Anthocopa papaveris, who fas.h.i.+ons her cells with poppy-petals. I do not know the flower-cutter, I have never seen her; but her art tells me plainly enough that she must establish herself in some gallery wrought by others, as, for instance, in an Earth-worm's burrow.

We have but to see the nest of a Cotton-bee to convince ourselves that its builder cannot at the same time be an indefatigable navvy. When and newly-felted and not yet made sticky with honey, the wadded purse is by far the most elegant known specimen of entomological nest-building, especially where the cotton is of a brilliant white, as is frequently the case in the manufacturers of the Girdled Anthidium. No bird's-nest, however deserving of our admiration, can vie in fineness of flock, in gracefulness of form, in delicacy of felting with this wonderful bag, which our fingers, even with the aid of tools, could hardly imitate, for all their dexterity. I abandon the attempt to understand how, with its little bales of cotton brought up one by one, the insect, no otherwise gifted than the kneaders of mud and the makers of leafy baskets, manages to felt what it has collected into a h.o.m.ogeneous whole and then to work the product into a thimble-shaped wallet. Its tools as a master-fuller are its legs and its mandibles, which are just like those possessed by the mortar-kneaders and Leaf-cutters; and yet, despite this similarity of outfit, what a vast difference in the results obtained!

To see the Cotton-bees' talents in action seems an undertaking fraught with innumerable difficulties: things happen at a depth inaccessible to the eye; and to persuade the insect to work in the open does not lie in our power. One resource remained and I did not fail to turn to it, though hitherto I have been wholly unsuccessful. Three species, Anthidium diadema, A. manicatum and A. florentinum--the first-named in particular--show themselves quite ready to take up their abode in my reed-apparatus. All that I had to do was to replace the reeds by gla.s.s tubes, which would allow me to watch the work without disturbing the insect. This stratagem had answered perfectly with the Three-horned Osmia and Latreille's Osmia, whose little housekeeping-secrets I had learnt thanks to the transparent dwelling-house. Why should it not answer for its Cotton-bees and, in the same way, with the Leaf-cutters?

I almost counted on success. Events betrayed my confidence. For four years I supplied my hives with gla.s.s tubes and not once did the Cotton-weavers or the Leaf-cutters condescend to take up their quarters in the crystal palaces. They always preferred the hovel provided by the reed. Shall I persuade them one day? I do not abandon all hope.

Meanwhile, let me describe the little that I saw. More or less stocked with cells, the reed is at last closed, right at the orifice, with a thick plug of cotton, usually coa.r.s.er than the wadding of the honey-satchels. It is the equivalent of the Three-horned Osmia's barricade of mud, of the leaf-putty of Latreille's Osmia, of the Megachiles' barrier of leaves cut into disks. All these free tenants are careful to shut tight the door of the dwelling, of which they have often utilized only a portion. To watch the building of this barricade, which is almost external work, demands but a little patience in waiting for the favourable moment.

The Anthidium arrives at last, carrying the bale of cotton for the plugging. With her fore-legs she tears it apart and spreads it out; with her mandibles, which go in closed and come out open, she loosens the hard lumps of flock; with her forehead she presses each new layer upon the one below. And that is all. The insect flies off, returns the richer by another bale and repeats the performance until the cotton barrier reaches the level of the opening. We have here, remember, a rough task, in no way to be compared with the delicate manufacturer of the bags; nevertheless, it may perhaps tell us something of the general procedure of the finer work. The legs do the carding, the mandibles the dividing, the forehead the pressing; and the play of these implements produces the wonderful cus.h.i.+oned wallet. That is the mechanism in the lump; but what of the artistry?

Let us leave the unknown for facts within the scope of observation. I will question the Diadem Anthidium in particular, a frequent inmate of my reeds. I open a reed-stump about two decimetres long by twelve millimetres in diameter. (About seven and three-quarter inches by half an inch.--Translator's Note.) The end is occupied by a column of cotton-wool comprising ten cells, without any demarcation between them on the outside, so that their whole forms a continuous cylinder.

Moreover, thanks to a close felting, the different compartments are soldered together, so much so that, when pulled by the end, the cotton edifice does not break into sections, but comes out all in one piece.

One would take it for a single cylinder, whereas in reality the work is composed of a series of chambers, each of which has been constructed separately, independently of the one before, except perhaps at the base.

For this reason, short of ripping up the soft dwelling, still full of honey, it is impossible to ascertain the number of storeys; we must wait until the coc.o.o.ns are woven. Then our fingers can tell the cells by counting the knots that resist pressure under the cover of wadding. This general structure is easily explained. A cotton bag is made, with the sheath of the reed as a mould. If this guiding sheath were lacking, the thimble shape would be obtained all the same, with no less elegance, as is proved by the Girdled Anthidium, who makes her nest in some hiding-place or other in the walls or the ground. When the purse is finished, the provisions come and the egg, followed by the closing of the cell. We do not here find the geometrical lid of the Leaf-cutters, the pile of disks tight-set in the mouth of the jar. The bag is closed with a cotton sheet whose edges are soldered by a felting-process to the edges of the opening. The soldering is so well done that the honey-pouch and its cover form an indivisible whole. Immediately above it, the second cell is constructed, having its own base. At the beginning of this work, the insect takes care to join the two storeys by felting the ceiling of the first to the floor of the second. Thus continued to the end, the work, with its inner solderings, becomes an unbroken cylinder, in which the beauties of the separate wallets disappear from view. In very much the same fas.h.i.+on, but with less adhesion among the different cells, do the Leaf-cutters act when stacking their jars in a column without any external division into storeys.

Let us return to the reed-stump which gives us these details. Beyond the cotton-wool cylinder wherein ten coc.o.o.ns are lodged in a row comes an empty s.p.a.ce of half a decimetre or more. (About two inches.--Translator's Note.) The Osmiae and the Leaf-cutters are also accustomed to leave these long, deserted vestibules. The nest ends, at the orifice of the reed, with a strong plug of flock coa.r.s.er and less white than that of the cells. This use of closing-materials which are less delicate in texture but of greater resisting-power, while not an invariable characteristic, occurs frequently enough to make us suspect that the insect knows how to distinguish what is best suited now to the snug sleeping-berth of the larvae, anon to the defensive barricade of the home. Sometimes the choice is an exceedingly judicious one, as is shown by the nest of the Diadem Anthidium. Time after time, whereas the cells were composed of the finest grade of white cotton, gathered from Centaurea solsticialis, or St. Barnaby's thistle, the barrier at the entrance, differing from the rest of the work in its yellow colouring, was a heap of close-set bristles supplied by the scallop-leaved mullein.

The two functions of the wadding are here plainly marked. The delicate skin of the larvae needs a well-padded cradle; and the mother collects the softest materials that the cottony plants provide. Rivalling the bird, which furnishes the inside of the nest with wool and strengthens the outside with sticks, she reserves for the grubs' mattress the finest down, so hard to find and collected with such patience. But, when it becomes a matter of shutting the door against the foe, then the entrance bristles with forbidding caltrops, with stiff, p.r.i.c.kly hairs.

This ingenious system of defence is not the only one known to the Anthidia. More distrustful still, the Manicate Anthidium leaves no s.p.a.ce in the front part of the reed. Immediately after the column of cells, she heaps up, in the uninhabited vestibule, a conglomeration of rubbish, whatever chance may offer in the neighbourhood of the nest: little pieces of gravel, bits of earth, grains of sawdust, particles of mortar, cypress-catkins, broken leaves, dry Snail-droppings and any other material that comes her way. The pile, a real barricade this time, blocks the reed completely to the end, except about two centimetres (About three-quarters of an inch.--Translator's Note.) left for the final cotton plug. Certainly no foe will break in through the double rampart; but he will make an insidious attack from the rear.

The Leucopsis will come and, with her long probe, thanks to some imperceptible fissure in the tube, will insert her dread eggs and destroy every single inhabitant of the fortress. Thus are the Manicate Anthidium's anxious precautions outwitted.

If we had not already seen the same thing with the Leaf-cutters, this would be the place to enlarge upon the useless tasks undertaken by the insect when, with its ovaries apparently depleted, it goes on spending its strength with no maternal object in view and for the sole pleasure of work. I have come across several reeds stopped up with flock though containing nothing at all, or else furnished with one, two or three cells devoid of provisions or eggs. The ever-imperious instinct for gathering cotton and felting it into purses and heaping it into barricades persists, fruitlessly, until life fails. The Lizard's tail wriggles, curls and uncurls after it is detached from the animal's body.

In these reflex movements, I seem to see not an explanation, certainly, but a rough image of the industrious persistency of the insect, still toiling away at its business, even when there is nothing useful left to do. This worker knows no rest but death.

I have said enough about the dwelling of the Diadem Anthidium; let us look at the inhabitant and her provisions. The honey is pale-yellow, h.o.m.ogeneous and of a semifluid consistency, which prevents it from trickling through the porous cotton bag. The egg floats on the surface of the heap, with the end containing the head dipped into the paste. To follow the larva through its progressive stages is not without interest, especially on account of the coc.o.o.n, which is one of the most singular that I know. With this object in view, I prepare a few cells that lend themselves to observation. I take a pair of scissors, slice a piece off the side of the cotton-wool purse, so as to lay bare both the victuals and the consumer, and place the ripped cell in a short gla.s.s tube.

During the first few days, nothing striking happens. The little grub, with its head still plunged in the honey, slakes its thirst with long draughts and waxes fat. A moment comes...But let us go back a little farther, before broaching this question of sanitation.

Every grub, of whatever kind, fed on provisions collected by the mother and placed in a narrow cell is subject to conditions of health unknown to the roving grub that goes where it likes and feeds itself on what it can pick up. The first, the recluse, is no more able than the second, the gadabout, to solve the problem of a food which can be entirely a.s.similated, without leaving an unclean residue. The second gives no thought to these sordid matters: any place suits it for getting rid of that difficulty. But what will the other do with its waste matter, cooped up as it is in a tiny cell stuffed full of provisions? A most unpleasant mixture seems inevitable. Picture the honey-eating grub floating on liquid provisions and fouling them at intervals with its excretions! The least movement of the hinder-part would cause the whole to amalgamate; and what a broth that would make for the delicate nursling! No, it cannot be; those dainty epicures must have some method of escaping these horrors.

They all have, in fact, and most original methods at that. Some take the bull by the horns, so to speak, and, in order not to soil things, refrain from uncleanliness until the end of the meal: they keep the dropping-trap closed as long as the victuals are unfinished. This is a radical scheme, but not in every one's power, it appears. It is the course adopted, for instance, by the Sphex-wasps and the Anthophora-bees, who, when the whole of the food is consumed, expel at one shot the residues ama.s.sed in the intestines since the commencement of the repast.

Others, the Osmiae in particular, accept a compromise and begin to relieve the digestive tract when a suitable s.p.a.ce has been made in the cell through the gradual disappearance of the victuals. Others again--more hurried these--find means of obeying the common law pretty early by engaging in stercoral manufactures. By a stroke of genius, they make the unpleasant obstruction into building-bricks. We already know the art of the Lily-beetle (Crioceris merdigera. Fabre's essay on this insect has not yet been translated into English; but readers interested in the matter will find a full description in "An Introduction to Entomology," by William Kirby, Rector of Barham, and William Spence: letter 21.--Translator's Note.), who, with her soft excrement, makes herself a coat wherein to keep cool in spite of the sun. It is a very crude and revolting art, disgusting to the eye. The Diadem Anthidium belongs to another school. With her droppings she fas.h.i.+ons masterpieces of marquetry and mosaic, which wholly conceal their base origin from the onlooker. Let us watch her labours through the windows of my tubes.

When the portion of food is nearly half consumed, there begins and goes on to the end a frequent defecation of yellowish droppings, each hardly the size of a pin's head. As these are ejected, the grub pushes them back to the circ.u.mference of the cell with a movement of its hinder-part and keeps them there by means of a few threads of silk. The work of the spinnerets, therefore, which is deferred in the others until the provisions are finished, starts earlier here and alternates with the feeding. In this way, the excretions are kept at a distance, away from the honey and without any danger of getting mixed with it. They end by becoming so numerous as to form an almost continuous screen around the larva. This excremental awning, made half of silk and half of droppings, is the rough draft of the coc.o.o.n, or rather a sort of scaffolding on which the stones are deposited until they are definitely placed in position. Pending the piecing together of the mosaic, the scaffolding keeps the victuals free from all contamination.

To get rid of what cannot be flung outside, by hanging it on the ceiling, is not bad to begin with; but to use it for making a work of art is better still. The honey has disappeared. Now commences the final weaving of the coc.o.o.n. The grub surrounds itself with a wall of silk, first pure white, then tinted reddish-brown by means of an adhesive varnish. Through its loose-meshed stuff, it seizes one by one the droppings hanging from the scaffold and inlays them firmly in the tissue. The same mode of work is employed by the Bembex-, Stizus-and Tachytes-wasps and other inlayers, who strengthen the inadequate woof of their coc.o.o.ns with grains of sand; only, in their cotton-wool purses, the Anthidium's grubs subst.i.tute for the mineral particles the only solid materials at their disposal. For them, excrement takes the place of pebbles.

And the work goes none the worse for it. On the contrary: when the coc.o.o.n is finished, any one who had not witnessed the process of manufacture would be greatly puzzled to state the nature of the workmans.h.i.+p. The colouring and the elegant regularity of the outer wrapper of the coc.o.o.n suggest some kind of basket-work made with tiny bits of bamboo, or a marquetry of exotic granules. I too let myself be caught by it in my early days and wondered in vain what the hermit of the cotton wallet had used to inlay her nymphal dwelling so prettily withal. To-day, when the secret is known to me, I admire the ingenuity of the insect capable of obtaining the useful and the beautiful out of the basest materials.

The coc.o.o.n has another surprise in store for us. The end containing the head finishes with a short conical nipple, an apex, pierced by a narrow shaft that establishes a communication between the inside and the out. This architectural feature is common to all the Anthidia, to the resin-workers who will occupy our attention presently, as well as to the cotton-workers. It is found nowhere outside the Anthidium group.

What is the use of this point which the larva leaves bare instead of inlaying it like the rest of the sh.e.l.l? What is the use of that hole, left quite open or, at most, closed at the bottom with a feeble grating of silk? The insect appears to attach great importance to it, from what I see. In point of fact, I watch the careful work of the apex. The grub, whose movements the hole enables me to follow, patiently perfects the lower end of the conical channel, polishes it and gives it an exactly circular shape; from time to time, it inserts into the pa.s.sage its two closed mandibles, whose points project a little way outside; then, opening them to a definite radius, like a pair of compa.s.ses, it widens the aperture and makes it regular.

I imagine, without venturing, however, to make a categorical statement, that the perforated apex is a chimney to admit the air required for breathing. Every pupa breathes in its sh.e.l.l, however compact this may be, even as the unhatched bird breathes inside the egg. The thousands of pores with which the sh.e.l.l is pierced allow the inside moisture to evaporate and the outer air to penetrate as and when needed. The stony caskets of the Bembex- and Stizus-wasps are endowed, notwithstanding their hardness, with similar means of exchange between the vitiated and the pure atmosphere. Can the sh.e.l.ls of the Anthidia be air-proof, owing to some modification that escapes me? In any case, this impermeability cannot be attributed to the excremental mosaic, which the coc.o.o.ns of the resin-working Anthidia do not possess, though endowed with an apex of the very best.

Shall we find an answer to the question in the varnish with which the silken fabric is impregnated? I hesitate to say yes and I hesitate to say no, for a host of coc.o.o.ns are coated with a similar lacquer though deprived of communication with the outside air. All said, without being able at present to account for its necessity, I admit that the apex of the Anthidia is a breathing-aperture. I bequeath to the future the task of telling us for what reasons the collectors of both cotton and resin leave a large pore in their sh.e.l.ls, whereas all the other weavers close theirs completely.

After these biological curiosities, it remains for me to discuss the princ.i.p.al subject of this chapter: the botanical origin of the materials of the nest. By watching the insect when busy at its harvesting, or else by examining its manufactured flock under the microscope, I was able to learn, not without a great expenditure of time and patience, that the different Anthidia of my neighbourhood have recourse without distinction to any cottony plant. Most of the wadding is supplied by the Compositae, particularly the following: Centaurea solsticialis, or St. Barnaby's thistle; C. paniculata, or panicled centaury; Echinops ritro, or small globe-thistle; Onopordon illyric.u.m, or Illyrian cotton-thistle; Helichrysum staechas, or wild everlasting; Filago germanica, or common cotton-rose. Next come the l.a.b.i.atae: Marrubium vulgare, or common white h.o.r.ehound; Ballota fetida, or stinking h.o.r.ehound; Calamintha nepeta, or lesser calamint; Salvia aethiopis, or woolly sage. Lastly, the Solanaceae: Verbasc.u.m thapsus, or shepherd's club; V. sinuatum, or scollop-leaved mullein.

The Cotton-bees' flora, we see, incomplete as it is in my notes, embraces plants of very different aspect. There is no resemblance in appearance between the proud candelabrum of the cotton-thistle, with its red tufts, and the humble stalk of the globe-thistle, with its sky-blue capitula; between the plentiful leaves of the mullein and the scanty foliage of the St. Barnaby's thistle; between the rich silvery fleece of the woolly sage and the short hairs of the everlasting. With the Anthidium, these clumsy botanical characteristics do not count; one thing alone guides her: the presence of cotton. Provided that the plant be more or less well-covered with soft wadding, the rest is immaterial to her.

Another condition, however, has to be fulfilled, apart from the fineness of the cotton-wool. The plant, to be worth shearing, must be dead and dry. I have never seen the harvesting done on fresh plants. In this way, the Bee avoids mildew, which would make its appearance in a ma.s.s of hairs still filled with sap.

Faithful to the plant recognized as yielding good results, the Anthidium arrives and resumes her gleaning on the edges of the parts denuded by earlier harvests. Her mandibles sc.r.a.pe away and pa.s.s the tiny fluffs, one by one, to the hind-legs, which hold the pellet pressed against the chest, mix with it the rapidly-increasing store of down and make the whole into a little ball. When this is the size of a pea, it goes back into the mandibles; and the insect flies off, with its bale of cotton in its mouth. If we have the patience to wait, we shall see it return to the same point, at intervals of a few minutes, so long as the bag is not made. The foraging for provisions will suspend the collecting of cotton; then, next day or the day after, the sc.r.a.ping will be resumed on the same stalk, on the same leaf, if the fleece be not exhausted. The owner of a rich crop appears to keep to it until the closing-plug calls for coa.r.s.er materials; and even then this plug is often manufactured with the same fine flock as the cells.

After ascertaining the diversity of cotton-fields among our native plants, I naturally had to enquire whether the Cotton-bee would also put up with exotic plants, unknown to her race; whether the insect would show any hesitation in the presence of woolly plants offered for the first time to the rakes of her mandibles. The common clary and the Babylonian centaury, with which I have stocked the harmas, shall be the harvest-fields; the reaper shall be the Diadem Anthidium, the inmate of my reeds.

The common clary, or toute-bonne, forms part, I know, of our French flora to-day; but it is an acclimatized foreigner. They say that a gallant crusader, returning from Palestine with his share of glory and bruises, brought back the toute-bonne from the Levant to help him cure his rheumatism and dress his wounds. From the lordly manor, the plant propagated itself in all directions, while remaining faithful to the walls under whose shelter the n.o.ble dames of yore used to grow it for their unguents. To this day, feudal ruins are its favourite resorts.

Crusaders and manors disappeared; the plant remained. In this case, the origin of the clary, whether historical or legendary, is of secondary importance. Even if it were of spontaneous growth in certain parts of France, the toute-bonne is undoubtedly a stranger in the Vaucluse district. Only once in the course of my long botanizing-expeditions across the department have I come upon this plant. It was at Caromb, in some ruins, nearly thirty years ago. I took a cutting of it; and since then the crusaders' sage has accompanied me on all my peregrinations.

My present hermitage possesses several tufts of it: but, outside the enclosure, except at the foot of the walls, it would be impossible to find one. We have, therefore, a plant that is new to the country for many miles around, a cotton-field which the Serignan Cotton-bees had never utilized before I came and sowed it.

Nor had they ever made use of the Babylonian centaury, which I was the first to introduce in order to cover my ungrateful stony soil with some little vegetation. They had never seen anything like the colossal centaury imported from the region of the Euphrates. Nothing in the local flora, not even the cotton-thistle, had prepared them for this stalk as thick as a child's wrist, crowned at a height of nine feet with a mult.i.tude of yellow b.a.l.l.s, nor for those great leaves spreading over the ground in an enormous rosette. What will they do in the presence of such a find? They will take possession of it with no more hesitation than if it were the humble St. Barnaby's thistle, the usual purveyor.

In fact, I place a few stalks of clary and Babylonian centaury, duly dried, near the reed-hives. The Diadem Anthidium is not long in discovering the rich harvest. Straight away the wool is recognized as being of excellent quality, so much so that, during the three or four weeks of nest-building, I can daily witness the gleaning, now on the clary, now on the centaury. Nevertheless the Babylonian plant appears to be preferred, no doubt because of its whiter, finer and more plentiful down. I keep a watchful eye on the sc.r.a.ping of the mandibles and the work of the legs as they prepare the pellet; and I see nothing that differs from the operations of the insect when gleaning on the globe-thistle and the St. Barnaby's thistle. The plant from the Euphrates and the plant from Palestine are treated like those of the district.

Thus we find what the Leaf-cutters taught us proved, in another way, by the cotton-gatherers. In the local flora, the insect has no precise domain; it reaps its harvest readily now from one species, now from another, provided that it find the materials for its manufactures. The exotic plant is accepted quite as easily as that of indigenous growth.

Lastly, the change from one plant to another, from the common to the rare, from the habitual to the exceptional, from the known to the unknown, is made suddenly, without gradual initiations. There is no novitiate, no training by habit in the choice of the materials for the nest. The insect's industry, variable in its details by sudden, individual and non-transmissible innovations, gives the lie to the two great factors of evolution: time and heredity.

CHAPTER 10. THE RESIN-BEES.