At the time when Fabricius (1) gave the genus Anthidium its name, a name still used in our classifications, entomologists troubled very little about the live animal; they worked on corpses, a dissecting-room method which does not yet seem to be drawing to an end. They would examine with a conscientious eye the antenna, the mandible, the wing, the leg, without asking themselves what use the insect had made of those organs in the exercise of its calling. The animal was classified very nearly after the manner adopted in crystallography. Structure was everything; life, with its highest prerogatives, intellect, instinct, did not count, was not worthy of admission into the zoological scheme.
It is true that an almost exclusively necrological study is obligatory at first. To fill one's boxes with insects stuck on pins is an operation within the reach of all; to watch those same insects in their mode of life, their work, their habits and customs is quite a different thing. The nomenclator who lacks the time and sometimes also the inclination takes his magnifying-glass, analyzes the dead body and names the worker without knowing its work. Hence the number of appellations the least of whose faults is that they are unpleasant to the ear, certain of them, indeed, being gross misnomers. Have we not, for instance, seen the name of Lithurgus, or stone-worker, given to a Bee who works in wood and nothing but wood? Such absurdities will be inevitable until the animal's profession is sufficiently familiar to lend its aid in the compiling of diagnoses. I trust that the future will see this magnificent advance in entomological science: men will reflect that the impaled specimens in our collections once lived and followed a trade; and anatomy will be kept in its proper place and made to leave due room for biology.
Fabricius did not commit himself with his expression Anthidium, which alludes to the love of flowers, but neither did he mention anything characteristic: as all Bees have the same passion in a very high degree, I see no reason to treat the Anthidia as more zealous looters than the others. If he had known their cotton nests, perhaps the Scandinavian naturalist would have given them a more logical denomination. As for me, in a language wherein technical parade is out of place, I will call them the Cotton-bees.
The term requires some limiting. To judge by my finds, in fact, the old genus Anthidium, that of the classifying entomologists, comprises in my district two very different corporations. One is known to us and works exclusively in wadding; the other, which we are about to study, works in resin, without ever having recourse to cotton. Faithful to my extremely simple principle of defining the worker, as far as possible, by his work, I will call the members of this guild the Resin-bees. Thus confining myself to the data supplied by my observations, I divide the Anthidium group into equal sections, of equal importance, for which I demand special generic titles; for it is highly illogical to call the carders of wool and the kneaders of resin by the same name. I surrender to those whom it concerns the honour of effecting this reform in the orthodox fashion.
Good luck, the friend of the persevering, made me acquainted in different parts of Vaucluse with four Resin-bees whose singular trade no one had yet suspected. To-day, I find them all four again in my own neighbourhood. They are the following: Anthidium septemdentatum, LATR., A. bellicosum, LEP., A. quadrilobum, LEP., and A. Latreillii, LEP. The first two make their nests in deserted Snail-shells; the other two shelter their groups of cells sometimes in the ground, sometimes under a large stone. We will first discuss the inhabitants of the Snail-shell. I made a brief reference to them in an earlier chapter, when speaking of the distribution of the sexes. This mere allusion, suggested by a study of a different kind, must now be amplified. I return to it with fuller particulars.
The stone-heaps in the Roman quarries near Serignan, which I have so often visited in search of the nests of the Osmia who takes up her abode in Snail-shells, supply me also with the two Resin-bees installed in similar quarters. When the Field-mouse has left behind him a rich collection of empty shells scattered all round his hay mattress under the slab, there is always a hope of finding some Snail-shells plugged with mud and, here and there, mixed with them, a few Snail-shells closed with resin. The two Bees work next door to each other, one using clay, the other gum. The excellence of the locality is responsible for this frequent cohabitation, shelter being provided by the broken stone from the quarry and lodgings by the shells which the Mouse has left behind.
At places where dead Snail-shells are few and far between, as in the crevices of rustic walls, each Bee occupies by herself the shells which she has found. But here, in the quarries, our crop will certainly be a double or even a treble one, for both Resin-bees frequent the same heaps. Let us, therefore, lift the stones and dig into the mound until the excessive dampness of the subsoil tells us that it is useless to look lower down. Sometimes at the moment of removing the first layer, sometimes at a depth of eighteen inches, we shall find the Osmia's Snail-shell and, much more rarely, the Resin-bee's. Above all, patience! The job is none of the most fruitful; nor is it exactly an agreeable one. By dint of turning over uncommonly jagged stones, our fingertips get hurt, lose their skin and become as smooth as though we had held them on a grindstone. After a whole afternoon of this work, our back will be aching, our fingers will be itching and smarting and we shall possess a dozen Osmia-nests and perhaps two or three Resin-bees' nests. Let us be content with that.
The Osmia's shells can be recognized at once, as being closed at the orifice with a clay cover. The Anthidium's call for a special examination, without which we should run a great risk of filling our pockets with cumbersome rubbish. We find a dead Snail-shell among the stones. Is it inhabited by the Resin-bee or not? The outside tells us nothing. The Anthidium's work comes at the bottom of the spiral, a long way from the mouth; and, though this is wide open, the eye cannot travel far enough along the winding stair. I hold up the doubtful shell to the light. If it is completely transparent, I know that it is empty and I put it back to serve for future nests. If the second whorl is opaque, the spiral contains something. What does it contain? Earth washed in by the rain? Remnants of the putrefied Snail? That remains to be seen. With a little pocket-trowel, the inquisitorial implement which always accompanies me, I make a wide window in the middle of the final whorl. If I see a gleaming resin floor, with incrustations of gravel, the thing is settled: I possess an Anthidium's nest. But, oh the number of failures that go to one success! The number of windows vainly opened in shells whose bottom is stuffed with clay or with noisome corpses! Thus picking shells among the overturned stone-heaps, inspecting them in the sun, breaking into them with the trowel and nearly always rejecting them, I manage, after repeated attempts, to obtain my materials for this chapter.
The first to hatch is the Seven-pronged Resin-bee (Anthidium septemdentatum). We see her, in the month of April, lumbering along to the rubbish-heaps in the quarries and the low boundary-walls, in search of her Snail-shell. She is a contemporary of the Three-horned Osmia, who begins operations in the last week of April, and often occupies the same stone-heap, settling in the next shell. She is well-advised to start work early and to be on neighbourly terms with the Osmia when the latter is building; in fact, we shall soon see the terrible dangers to which that same proximity exposes her dilatory rival in resin-work, Anthidium bellicosum.
The shell adopted in the great majority of cases is that of the Common Snail, Helix aspersa. It is sometimes of full size, sometimes half-developed. Helix nemoralis and H. caespitum, which are much smaller, also supply suitable lodgings; and this would as surely apply to any shell of sufficient capacity, if the places which I explore possessed others, as witness a nest which my son Emile has sent me from somewhere near Marseilles. This time, the Resin-bee is settled in Helix algira, the most remarkable of our land-shells because of the width and regularity of its spiral, which is copied from that of the Ammonites. This magnificent nest, a perfect specimen of both the Snail's work and the Bee's, deserves description before any other.
For a distance of three centimetres (2) from the mouth, the last spiral whorl contains nothing. At this inconsiderable depth, a partition is clearly seen. The moderate diameter of the passage accounts for the Anthidium's choice of this site to which our eye can penetrate. In the common Snail-shell, whose cavity widens rapidly, the insect establishes itself much farther back, so that, in order to see the terminal partition, we must, as I have said, make a lateral inlet. The position of this boundary-ceiling, which may come farther forward or farther back, depends on the variable diameter of the passage. The cells of the cocoons require a certain length and a certain breadth, which the mother finds by going higher up or lower down in the spiral, according to the shape of the shell. When the diameter is suitable, the last whorl is occupied up to the orifice, where the final lid appears, absolutely exposed to view. This is the case with the adult Helix nemoralis and H. caespitum, and also with the young Common Snail. We will not linger at present over this peculiarity, the importance of which will become manifest shortly.
Whether in the front or at the back of the spiral slope, the insect's work ends in a facade of coarse mosaic, formed of small, angular bits of gravel, firmly cemented with a gum the nature of which has to be ascertained. It is an amber-coloured material, semi-transparent, brittle, soluble in spirits of wine and burning with a sooty flame and a strong smell of resin. From these characteristics it is evident that the Bee prepares her gum with the resinous drops exuded by the Coniferae.
I think that I am even able to name the particular plant, though I have never caught the insect in the act of gathering its materials. Hard by the stone-heaps which I turn over for my collections there is a plentiful supply of brown-berried junipers. Pines are totally absent; and the cypress only appears occasionally near the houses. Moreover, among the vegetable remains which we shall see assisting in the protection of the nest, we often find the juniper's catkins and needles. As the resin-insect is economical of its time and does not fly far from the quarters familiar to it, the gum must have been collected on the shrub at whose foot the materials for the barricade have been gathered. Nor is this merely a local circumstance, for the Marseilles nest abounds in similar remnants. I therefore regard the juniper as the regular resin-purveyor, without, however, excluding the pine, the cypress and other Coniferae when the favourite shrub is absent.
The bits of gravel in the lid are angular and chalky in the Marseilles nest; they are round and flinty in most of the Serignan nests. In making her mosaic, the worker pays no heed to the form or colour of its component parts; she collects indiscriminately anything that is hard enough and not too large. Sometimes she lights upon treasures that give her work a more original character. The Marseilles nest shows me, neatly encrusted amid the bits of gravel, a tiny whole landshell, Pupa cineres. A nest in my own neighbourhood provides me with a pretty Snail-shell, Helix striata, forming a rose-pattern in the middle of the mosaic. These little artistic details remind me of a certain nest of Eumenes Amadei (3) which abounds in small shells. Ornamental shell-work appears to number its lovers among the insects.
After the lid of resin and gravel, an entire whorl of the spiral is occupied by a barricade of incongruous remnants, similar to that which, in the reeds, protects the row of cocoons of the Manicate Cotton-bee. It is curious to see exactly the same defensive methods employed by two builders of such different talents, one of whom handles flock, the other gum. The nest from Marseilles has for its barricade bits of chalky gravel, particles of earth, fragments of sticks, a few scraps of moss and especially juniper-catkins and needles. The Serignan nests, installed in Helix aspersa, have almost the same protective materials. I see bits of gravel, the size of a lentil, and the catkins and needles of the brown-berried juniper predominating. Next come the dry excretions of the Snail and a few rare little land-shells. A similar jumble of more or less everything found near the nest forms, as we know, the barricade of the Manicate Cotton-bee, who is also an adept at using the Snail's stercoral droppings after these have been dried in the sun. Let us observe finally that these dissimilar materials are heaped together without any cementing, just as the insect has picked them up. Resin plays no part in the mass; and we have only to pierce the lid and turn the shell upside down for the barricade to come dribbling to the ground. To glue the whole thing together does not enter into the Resin-bee's scheme. Perhaps such an expenditure of gum is beyond her means; perhaps the barricade, if hardened into a solid block, would afterwards form an invincible obstacle to the escape of the youngsters; perhaps again the mass of gravel is an accessory rampart, run up roughly as a work of secondary importance.
Amid these doubtful matters, I see at least that the insect does not look upon its barricade as indispensable. It employs it regularly in the large shells, whose last whorl, too spacious to be used, forms an unoccupied vestibule; it neglects it in the moderate shells, such as Helix nemoralis, in which the resin lid is level with the orifice. My excavations in the stone-heaps supply me with an almost equal number of nests with and without defensive embankments. Among the Cotton-bees, the Manicate Anthidium is not faithful either to her fort of little sticks and stones; I know some of her nests in which cotton serves every purpose. With both of them, the gravel rampart seems useful only in certain circumstances, which I am unable to specify.
On the other side of the outworks of the fortification, the lid and barricade, are the cells set more or less far down in the spiral, according to the diameter of the shell. They are bounded back and front by partitions of pure resin, without any encrustations of mineral particles. Their number is exceedingly restricted and is usually limited to two. The front room, which is larger because the width of the passage goes on increasing, is the abode of a male, superior in size to the other sex; the less spacious back room contains a female. I have already drawn attention in an earlier chapter to the wonderful problem submitted for our consideration by this breaking up of the laying into couples and this alternation of the males and females. Without calling for other work than the transverse partitions, the broadening stairway of the Snail-shell thus furnishes both sexes with house-room suited to their size.
The second Resin-bee that inhabits shells, Anthidium bellicosum, hatches in July and works during the fierce heat of August. Her architecture differs in no wise from that of her kinswoman of the springtime, so much so that, when we find a tenanted Snail-shell in a hole in the wall or under the stones, it is impossible to decide to which of the two species the nest belongs. The only way to obtain exact information is to break the shell and split the cocoons in February, at which time the nests of the summer Resin-bee are occupied by larvae and those of the spring Resin-bee by the perfect insect. If we shrink from this brutal method, we are still in doubt until the cocoons open, so great is the resemblance between the two pieces of work.
In both cases, we find the same lodging, Snail-shells of every size and every kind, just as they happen to come; the same resin lid, the inside gritty with tiny bits of stone, the outside almost smooth and sometimes ornamented with little shells; the same barricade not always present of various kinds of rubbish; the same division into two rooms of unequal size occupied by the two sexes. Everything is identical, down to the purveyor of the gum, the brown-berried juniper. To say more about the nest of the summer Resin-bee would be to repeat oneself.
There is only one thing that requires further investigation. I do not see the reason that prompts the two insects to leave the greater part of their shell empty in front, instead of occupying it entirely up to the orifice as the Osmia habitually does. As the mother's laying is broken up into intermittent shifts of a couple of eggs apiece, is it necessary that there should be a new home for each shift? Is the half-fluid resin unsuitable for the wide-spanned roofs which would have to be constructed when the diameter of the helical passage exceeded certain limits? Is the gathering of the cement too wearisome a task to leave the Bee any strength for making the numerous partitions which she would need if she utilized the spacious final whorl? I find no answer to these questions. I note the fact without interpreting it: when the shell is a large one, the front part, almost the whole of the last whorl, remains an empty vestibule.
To the spring Resin-bee, Anthidium septemdentatum, this less than half occupied lodging presents no drawbacks. A contemporary of the Osmia, often her neighbour under the same stone, the gum-worker builds her nest at the same period as the mud-worker; but there is no fear of mutual encroachments, for the two Bees, working next door to each other, watch their respective properties with a jealous eye. If attempts at usurpation were to be made, the owner of the Snail-shell would know how to enforce her rights as the first occupant.
For the summer Resin-bee, A. bellicosum, the conditions are very different. At the moment when the Osmia is building, she is still in the larval, or at most in the nymphal stage. Her abode, which would not be more absolutely silent if deserted, her shell, with its vast untenanted porch, will not tempt the earlier Resin-bee, who herself wants apartments right at the far end of the spiral, but it might suit the Osmia, who knows how to fill the shell with cells up to the mouth. The last whorl left vacant by the Anthidium is a magnificent lodging which nothing prevents the mason from occupying. The Osmia does seize upon it, in fact, and does so too often for the welfare of the unfortunate late-comer. The final resin lid takes the place, for the Osmia, of the mud stopper with which she cuts off at the back the portion of the spiral too narrow for her labours. Upon this lid she builds her mass of cells in so many storeys, after which she covers the whole with a thick defensive plug. In short, the work is conducted as though the Snail-shell contained nothing.
When July arrives, this doubly-tenanted house becomes the scene of a tragic conflict. Those below, on attaining the adult state, burst their swaddling-bands, demolish their resin partitions, pass through the gravel barricade and try to release themselves; those above, larvae still or budding pupae, prisoners in their shells until the following spring, completely block the way. To force a passage from the far-end of those catacombs is beyond the strength of the Resin-bee, already weakened by the effort of breaking out of her own nest. A few of the Osmia's partitions are damaged, a few cocoons receive slight injuries; and then, worn out with vain struggles, the captives abandon hope and perish behind the impregnable wall of earth. And with them perish also certain parasites, even less fit for the prodigious work of clearance: Zonites and Chryses (Chrysis flammea), of whom the first are consumers of provisions and the second of grubs.
This lamentable ending of the Resin-bee, buried alive under the Osmia's walls, is not a rare accident to be passed over in silence or mentioned in a few words; on the contrary, it happens very often; and its frequency suggests this thought: the school which sees in instinct an acquired habit treats the slightest favourable occurrence in the course of animal industry as the starting-point of an improvement which, transmitted by heredity and becoming in time more and more accentuated, at last grows into a settled characteristic common to the whole race. There is, it is true, a total absence of positive proofs in support of this theory; but it is stated with a wealth of hypothesis that leaves a thousand loopholes: 'Granting that...Supposing that...It may be...nothing need prevent us from believing... It is quite possible...' Thus argued the master; and the disciples have not yet hit upon anything better.
'If the sky were to fall,' said Rabelais, 'the larks would all be caught.'
Yes, but the sky stays up; and the larks go on flying.
'If things happened in such and such a way,' says our friend, 'instinct may have undergone variations and modifications.'
Yes, but are you quite sure that things happened as you say?
I banish the word 'if' from my vocabulary. I suppose nothing, I take nothing for granted; I pluck the brutal fact, the only thing that can be trusted; I record it and then ask myself what conclusion rests upon its solid framework. From the fact which I have related we may draw the following inference:
'You say that any modification profitable to the animal is transmitted throughout a series of favoured ones who, better equipped with tools, better endowed with aptitudes, abandon the ancient usages and replace the primitive species, the victim of the struggle for life. You declare that once, in the dim distance of the ages, a Bee found herself by accident in possession of a dead Snail-shell. The safe and peaceful lodging pleased her fancy. On and on went the hereditary liking; and the Snail-shell proved more and more agreeable to the insect's descendants, who began to look for it under the stones, so that later generations, with the aid of habit, ended by adopting it as the ancestral dwelling. Again by accident, the Bee happened upon a drop of resin. It was soft, plastic, well-suited for the partitioning of the Snail-shell; it soon hardened into a solid ceiling. The Bee tried the resinous gum and benefited by it. Her successors also benefited by it, especially after improving it. Little by little, the rubble-work of the lid and of the gravel barricade was invented: an enormous improvement, of which the race did not fail to take advantage. The defensive fortification was the finishing-touch to the original structure. Here we have the origin and development of the instinct of the Resin-bees who make their home in Snail-shells.'
This glorious genesis of insect ways and means lacks just one little thing: probability. Life everywhere, even among the humble, has two phases: its share of good and its share of evil. Avoiding the latter and seeking the former is the rough balance-sheet of life's actions. Animals, like ourselves, have their portion of the sweet and the bitter: they are just as anxious to reduce the second as to increase the first; for, with them as with us,
De malheurs evites le bonheur se compose. (Bad luck missed is good luck gained.)
If the Bee has so faithfully handed down her casual invention of a resin nest built inside a Snail-shell, then there is no denying that she must have just as faithfully handed down the means of averting the terrible danger of belated hatchings. A few mothers, escaping at rare intervals from the catacombs blocked by the Osmiae, must have retained a lively memory, a powerful impression of their desperate struggle through the mass of earth; they must have inspired their descendants with a dread of those vast dwellings where the stranger comes afterwards and builds; they must have taught them by habit the means of safety, the use of the medium-sized shell, which the nest fills to the mouth. So far as the prosperity of the race was concerned, the discontinuance of the system of empty vestibules was far more important than the invention of the barricade, which is not altogether indispensable: it would have saved them from perishing miserably, behind impenetrable walls, and would have considerably increased the numbers of their posterity.
Thousands and thousands of experiments have been made throughout the ages with Snail-shells of average dimensions: the thing is certain, because I find many of them to-day. Well, have these life-saving experiments, with their immense importance to the race, become general by hereditary bequest? Not at all: the Resin-bee persists in using big Snail-shells just as though her ancestors had never known the danger of the Osmia-blocked vestibule. Once these facts are duly recognized, the conclusion is irresistible: it is obvious that, as the insect does not hand down the casual modification tending towards the avoidance of what is to its disadvantage, neither does it hand down the modification leading to the adoption of what is to its advantage. However lively the impression made upon the mother, the accidental leaves no trace in the offspring. Chance plays no part in the genesis of the instincts.
Next to these tenants of the Snail-shells we have two other Resin-bees who never come to the shells for a cabin for their nests. They are Anthidium quadrilobum, LEP., and A. Latreillii, LEP., both exceedingly uncommon in my district. If we meet them very rarely, however, this may well be due to the difficulty of seeing them; for they lead extremely solitary and wary lives. A warm nook under some stone or other; the deserted streets of an Ant-hill in a sun-baked bank; a Beetle's vacant burrow a few inches below the ground; in short, a cavity of some sort, perhaps arranged by the Bee's own care: these are the only establishments which I know them to occupy. And here, with no other shelter than the cover of the refuge, they build a mass of cells joined together and grouped into a sphere, which, in the case of the Four-lobed Resin-bee, attains the size of a man's fist and, in that of Latreille's Resin-bee, the size of a small apple.
At first sight, we remain very uncertain as to the nature of the strange ball. It is brown, rather hard, slightly sticky, with a bituminous smell. Outside are encrusted a few bits of gravel, particles of earth, heads of large-sized Ants. This cannibal trophy is not a sign of barbarous customs: the Bee does not decapitate Ants to adorn her hut. An inlayer, like her colleagues of the Snail-shell, she gathers any hard granule near at hand capable of strengthening her work; and the dried skulls of Ants, which are frequent around about her abode, are in her eyes building-stones of equal value to the pebbles. One and all employ whatever they can find without much seeking. The inhabitant of the shell, in order to construct her barricade, makes shift with the dry excrement of the nearest Snail; the denizen of the flat stones and of the roadside banks frequented by the Ants does what she can with the heads of the defunct and, should these be lacking, is ready to replace them with something else. Moreover, the defensive inlaying is slight; we see that the insect attaches no great importance to it and has every confidence in the stout wall of the home.
The material of which the work is made at first suggests some rustic wax, much coarser than that of the Bumble-bees, or rather some tar of unknown origin. We think again and then recognize in the puzzling substance the semitransparent fracture, the quality of becoming soft when exposed to heat and of burning with a smoky flame, the solubility in spirits of wine in short, all the distinguishing characteristics of resin. Here then are two more collectors of the exudations of the Coniferae. At the points where I find their nests are Aleppo pines, cypresses, brown-berried junipers and common junipers. Which of the four supplies the mastic? There is nothing to tell us. Nor is there anything to explain how the native amber-colour of the resin is replaced in the work of both Bees by a dark-brown hue resembling that of pitch. Does the insect collect resin impaired by the weather, soiled by the sanies of rotten wood? When kneading it, does it mix some dark ingredient with it? I look upon this as possible, but not as proved, since I have never seen the Bee collecting her resin.
While this point escapes me, another of higher interest appears most plainly; and that is the large amount of resinous material used in a single nest, especially in that of Anthidium quadrilobum, in which I have counted as many as twelve cells. The nest of the Mason-bee of the Pebbles is hardly more massive. For so costly an establishment, therefore, the Resin-bee collects her pitch on the dead pine as copiously as the Mason-bee collects her mortar on the macadamized road. Her workshop no longer shows us the niggardly partitioning of a Snail-shell with two or three drops of resin; what we see is the whole building of the house, from the basement to the roof, from the thick outer walls to the partitions of the rooms. The cement expended would be enough to divide hundreds of Snail-shells, wherefore the title of Resin-bee is due first and foremost to this master-builder in pitch. Honourable mention should be awarded to A. Latreillii, who rivals her fellow-worker as far as her smaller stature permits. The other manipulators of resin, those who build partitions in Snail-shells, come third, a very long way behind.
And now, with the facts to support us, let us philosophize a little. We have here, recognized as of excellent standard by all the expert classifiers, so fastidious in the arrangement of their lists, a generic group, called Anthidium, containing two guilds of workers entirely dissimilar in character: the cotton-fullers and the resin-kneaders. It is even possible that other species, when their habits are better known, will come and increase this variety of manufactures. I confine myself to the little that I know and ask myself in what the manipulator of cotton differs from the manipulator of resin as regards tools, that is to say, organs. Certainly, when the genus Anthidium was set down by the classifiers, they were not wanting in scientific precision: they consulted, under the lens of the microscope, the wings, the mandibles, the legs, the harvesting-brush, in short, all the details calculated to assist the proper delimitation of the group. After this minute examination by the experts, if no organic differences stand revealed, the reason is that they do not exist. Any dissimilarity of structure could not escape the accurate eyes of our learned taxonomists. The genus, therefore, is indeed organically homogeneous; but industrially it is thoroughly heterogeneous. The implements are the same and the work is different.
That eminent Bordeaux entomologist, Professor Jean Perez, to whom I communicated the misgivings aroused in my mind by the contradictory nature of my discoveries, thinks that he has found the solution of the difficulty in the conformation of the mandibles. I extract the following passage from his volume, "Les Abeilles":
'The cotton-pressing females have the edge of their mandibles cut out into five or six little teeth, which make an instrument admirably suited for scraping and removing the hairs from the epidermis of the plants. It is a sort of comb or teasel. The resin-kneading females have the edge of the mandible not toothed, but simply curved; the tip alone, preceded by a notch which is pretty clearly marked in some species, forms a real tooth; but this tooth is blunt and does not project. The mandible, in short, is a kind of spoon perfectly fitted to remove the sticky matter and to shape it into a ball.'
Nothing better could be said to explain the two sorts of industry: in the one case, a rake which gathers the wool; in the other, a spoon which scoops up the resin. I should have left it at that and felt quite content without further investigation, if I had not had the curiosity to open my boxes and, in my turn, to take a good look, side by side, at the workers in cement and the workers in cotton. Allow me, my learned master, to whisper in your ear what I saw.
The first that I examine is Anthidium septemdentatum. A spoon: yes, it is just that. Powerful mandibles, shaped like an isosceles triangle, flat above, hollowed out below; and no indentations, none whatsoever. A splendid tool, as you say, for gathering the viscous pellet; quite as efficacious in its kind of work as is the rake of the toothed mandibles for gathering cotton. Here certainly is a creature potently-gifted, even though it be for a poor little task, the scooping up of two or three drops of glue.
Things are not quite so satisfactory with the second Resin-bee of the Snail-shells, A. bellicosum. I find that she has three teeth to her mandibles. Still, they are slight and project very little. Let us say that this does not count, even though the work is exactly the same. With A. quadrilobum the whole thing breaks down. She, the queen of Resin-bees; she, who collects a lump of mastic the size of one's fist, enough to subdivide hundreds of her kinswomen's Snail-shells: well, she, by way of a spoon, carries a rake! On the wide edges of her mandibles stand four teeth, as long and pointed as those of the most zealous cotton-gleaner. A. florentinum, that mighty manufacturer of cotton-goods, can hardly rival her in respect of combing-tools. And nevertheless, with her toothed implement, a sort of saw, the Resin-bee collects her great heap of pitch, load by load; and the material is carried not rigid, but sticky, half-fluid, so that it may amalgamate with the previous lots and be fashioned into cells.
A. Latreillii, without having a very large implement, also bears witness to the possibility of heaping up soft resin with a rake; she arms her mandibles with three or four sharply-cut teeth. In short, out of four Resin-bees, the only four that I know, one is armed with a spoon, if this expression be really suited to the tool's function; the three others are armed with a rake; and it so happens that the most copious heap of resin is just the work of the rake with the most teeth to it, a tool suited to the cotton-reapers, according to the views of the Bordeaux entomological expert.
No, the explanation that appealed to me so much at first is not admissible. The mandible, whether supplied with teeth or not, does not account at all for the two manufactures. May we, in this predicament, have recourse to the general structure of the insect, although this is not distinctive enough to be of much use to us? Not so either; for, in the same stone-heaps where the Osmia and the two Resin-bees of the Snail-shells work, I find from time to time another manipulator of mastic who bears no structural relationship whatever to the genus Anthidium. It is a small-sized Mason-wasp, Odynerus alpestris, SAUSS. She builds a very pretty nest with resin and gravel in the shells of the young Common Snail, of Helix nemoralis and sometimes of Bulimulus radiatus. I will describe her masterpiece on some other occasion. To one acquainted with the genus Odynerus, any comparison with the Anthidia would be an inexcusable error. In larval diet, in shape, in habits, they form two dissimilar groups, very far removed one from the other. The Anthidia feed their offspring on honey-bread; the Odyneri feed it on live prey. Well, with her slender form, her weakly frame, in which the most clear-seeing eye would seek in vain for a clue to the trade practised, the Alpine Odynerus, the game-lover, uses pitch in the same way as the stout and massive Resin-bee, the honey-lover. She even uses it better, for her mosaic of tiny pebbles is much prettier than the Bee's and no less solid. With her mandibles, this time neither spoon nor rake, but rather a long forceps slightly notched at the tip, she gathers her drop of sticky matter as dexterously as do her rivals with their very different outfit. Her case will, I think, persuade us that neither the shape of the tool nor the shape of the worker can explain the work done.
I will go further: I ask myself in vain the reason of this or that trade in the case of a fixed species. The Osmiae make their partitions with mud or with a paste of chewed leaves; the Mason-bees build with cement; the Pelopaeus-wasps fashion clay pots; the Megachiles made disks cut from leaves into urns; the Anthidia felt cotton into purses; the Resin-bees cement together little bits of gravel with gum; the Carpenter-bees and the Lithurgi bore holes in timber; the Anthophorae tunnel the roadside slopes. Why all these different trades, to say nothing of the others? How are they prescribed for the insect, this one rather than that?
I foresee the answer: they are prescribed by the organization. An insect excellently equipped for gathering and felting cotton is ill-equipped for cutting leaves, kneading mud or mixing resin. The tool in its possession decides its trade.
This is a very simple explanation, I admit, and one within the scope of everybody: in itself a sufficient recommendation for any one who has neither the inclination nor the time to undertake a more thorough investigation. The popularity of certain speculative views is due entirely to the easy food which they provide for our curiosity. They save us much long and often irksome study; they impart a veneer of general knowledge. There is nothing that achieves such immediate success as an explanation of the riddle of the universe in a word or two. The thinker does not travel so fast: content to know little so that he may know something, he limits his field of search and is satisfied with a scanty harvest, provided that the grain be of good quality. Before agreeing that the tool determines the trade, he wants to see things with his own eyes; and what he observes is far from confirming the sweeping statement. Let us share his doubts for a moment and look into matters more closely.
Franklin left us a maxim which is much to the point here. He said that a good workman should be able to plane with a saw and to saw with a plane. The insect is too good a workman not to follow the advice of the sage of Boston. Its industry abounds in instances where the plane takes the place of the saw, or the saw of the plane; its dexterity makes good the inadequacy of the implement. To go no further, have we not just seen different artisans collecting and using pitch, some with spoons, others with rakes, others again with pincers? Therefore, with such equipment as it possesses, the insect would be capable of abandoning cotton for leaves, leaves for resin, resin for mortar, if some predisposition of talent did not make it keep to its speciality.
These few lines, which are the outcome not of a heedless pen but of mature reflection, will set people talking of hateful paradoxes. We will let them talk and we will submit the following proposition to our adversaries: take an entomologist of the highest merit, a Latreille (4), for instance, versed in all the details of the structure of insects but utterly unacquainted with their habits. He knows the dead insect better than anybody, but he has never occupied himself with the living insect. As a classifier, he is beyond compare; and that is all. We ask him to examine a Bee, the first that comes to hand, and to name her trade from her tools.
Come, be honest: could he? Who would dare put him to such a test? Has personal experience not fully convinced us that the mere examination of the insect can tell us nothing about its particular industry? The baskets on its legs and the brush on its abdomen will certainly inform us that it collects honey and pollen; but its special art will remain an utter secret, notwithstanding all the scrutiny of the microscope. In our own industries, the plane denotes the joiner, the trowel the mason, the scissors the tailor, the needle the seamstress. Are things the same in animal industry? Just show us, if you please, the trowel that is a certain sign of the mason-insect, the chisel that is a positive characteristic of the carpenter-insect, the iron that is an authentic mark of the pinking-insect; and as you show them, say:
'This one cuts leaves; that one bores wood; that other mixes cement.'
And so on, specifying the trade from the tool.
You cannot do it, no one can; the worker's speciality remains an impenetrable secret until direct observation intervenes. Does not this incapacity, even of the most expert, proclaim loudly that animal industry, in its infinite variety, is due to other causes besides the possession of tools? Certainly, each of those specialists requires implements; but they are rough and ready implements, good for all sorts of purposes, like the tool of Franklin's workman. The same notched mandible that reaps cotton, cuts leaves and moulds pitch also kneads mud, scrapes decayed wood and mixes mortar; the same tarsus that manufactures cotton and disks cut out of leaves is no less clever at the art of making earthen partitions, clay turrets and gravel mosaics.
What then is the reason of these thousand industries? In the light of facts, I can see but one: imagination governing matter. A primordial inspiration, a talent antecedent to the actual form, directs the tool instead of being subordinate to it. The instrument does not determine the manner of industry; the tool does not make the workman. At the beginning there is an object, a plan, in view of which the animal acts, unconsciously. Have we eyes to see with, or do we see because we have eyes? Does the function create the organ, or the organ the function? Of the two alternatives, the insect proclaims the first. It says:
'My industry is not imposed upon me by the implement which I possess; what I do is to use the implement, such as it is, for the talent with which I am gifted.'
It says to us, in its own way:
'The function has determined the organ; vision is the reason of the eye.'
In short, it repeats to us Virgil's profound reflection:
'Mens agitat molem'; 'Mind moves matter.'