Restore the nests to their original places, exchange them yet once again and both Bees, after a short hesitation which the great difference between the two nests is enough to explain, will pursue the work in the cell of her own making and in the strange cell alternately. At last the egg is laid and the sanctuary closed, no matter what nest happens to be occupied at the moment when the provisioning reaches completion. These incidents are sufficient to show why I hesitate to give the name of memory to the singular faculty that brings the insect back to her nest with such unerring precision and yet does not allow her to distinguish her work from some one else's, however great the difference may be.
We will now experiment with Chalicodoma muraria from another psychological point of view. Here is a Mason-bee building; she is at work on the first course of her cell. I give her in exchange a cell not only finished as a structure, but also filled nearly to the top with honey. I have just stolen it from its owner, who would not have been long before laying her egg in it. What will the Mason do in the presence of this munificent gift, which saves her the trouble of building and harvesting? She will leave the mortar no doubt, finish storing the Bee-bread, lay her egg and seal up. A mistake, an utter mistake: our logic is not the logic of the insect, which obeys an inevitable, unconscious prompting. It has no choice as to what it shall do; it cannot discriminate between what is and what is not advisable; it glides, as it were, down an irresistible slope prepared beforehand to bring it to a definite end. This is what the facts that still remain to be stated proclaim with no uncertain voice.
The Bee who was building and to whom I offer a cell ready-built and full of honey does not lay aside her mortar for that. She was doing mason's work; and, once on that tack, guided by the unconscious impulse, she has to keep masoning, even though her labour be useless, superfluous and opposed to her interests. The cell which I give her is certainly perfect, looked upon as a building, in the opinion of the master-builder herself, since the Bee from whom I took it was completing the provision of honey. To touch it up, especially to add to it, is useless and, what is more, absurd. No matter: the Bee who was masoning will mason. On the aperture of the honey-store she lays a first course of mortar, followed by another and yet another, until at last the cell is a third taller then the regulation height. The masonry-task is now done, not as perfectly, it is true, as if the Bee had gone on with the cell whose foundations she was laying at the moment when I exchanged the nests, but still to an extent which is more than enough to prove the overpowering impulse which the builder obeys. Next comes the victualling, which is also cut short, lest the honey-store swelled by the joint contributions of the two Bees should overflow. Thus the Mason-bee who is beginning to build and to whom we give a complete cell, a cell filled with honey, makes no change in the order of her work: she builds first and then victuals. Only she shortens her work, her instinct warning her that the height of the cell and the quantity of honey are beginning to assume extravagant proportions.
The converse is equally conclusive. To a Mason-bee engaged in victualling I give a nest with a cell only just begun and not at all fit to receive the paste. This cell, with its last course still wet with its builder's saliva, may or may not be accompanied by other cells recently closed up, each with its honey and its egg. The Bee, finding this in the place of her half-filled honey-store, is greatly perplexed what to do when she comes with her harvest to this unfinished, shallow cup, in which there is no place to put the honey. She inspects it, measures it with her eyes, tries it with her antennae and recognizes its insufficient capacity. She hesitates for a long time, goes away, comes back, flies away again and soon returns, eager to deposit her treasure. The insect's embarrassment is most evident; and I cannot help saying, inwardly:
'Get some mortar, get some mortar and finish making the warehouse. It will only take you a few moments; and you will have a cupboard of the right depth.'
The Bee thinks differently: she was storing her cell and she must go on storing, come what may. Never will she bring herself to lay aside the pollen-brush for the trowel; never will she suspend the foraging which is occupying her at this moment to begin the work of construction which is not yet due. She will rather go in search of a strange cell, in the desired condition, and slip in there to deposit her honey, at the risk of meeting with a warm reception from the irate owner. She goes off, in fact, to try her luck. I wish her success, being myself the cause of this desperate act. My curiosity has turned an honest worker into a robber.
Things may take a still more serious turn, so invincible, so imperious is the desire to have the booty stored in a safe place without delay. The uncompleted cell which the Bee refuses to accept instead of her own finished warehouse, half-filled with honey, is often, as I said, accompanied by other cells, not long closed, each containing its Bee-bread and its egg. In this case, I have sometimes, though not always, witnessed the following: when once the Bee realises the shortcomings of the unfinished nest, she begins to gnaw the clay lid closing one of the adjoining cells. She softens a part of the mortar cover with saliva and patiently, atom by atom, digs through the hard wall. It is very slow work. A good half-hour elapses before the tiny cavity is large enough to admit a pin's head. I wait longer still. Then I lose patience; and, fully convinced that the Bee is trying to open the store-room, I decide to help her to shorten the work. The upper part of the cell comes away with it, leaving the edges badly broken. In my awkwardness, I have turned an elegant vase into a wretched cracked pot.
I was right in my conjecture: the Bee's intention was to break open the door. Straight away, without heeding the raggedness of the orifice, she settles down in the cell which I have opened for her. Time after time, she fetches honey and pollen, though the larder is already fully stocked. Lastly, she lays her egg in this cell which already contains an egg that is not hers, having done which she closes the broken aperture to the best of her ability. So this purveyor had neither the knowledge nor the power to bow to the inevitable. I had made it impossible for her to go on with her purveying, unless she first completed the unfinished cell substituted for her own. But she did not retreat before that impossible task. She accomplished her work, but in the absurdest way: by injuriously trespassing upon another's property, by continuing to store provisions in a cupboard already full to overflowing, by laying her egg in a cell in which the real owner had already laid and lastly by hurriedly closing an orifice that called for serious repairs. What better proof could be wished of the irresistible propensity which the insect obeys?
Lastly, there are certain swift and consecutive actions so closely interlinked that the performance of the second demands a previous repetition of the first, even when this action has become useless. I have already described how the Yellow-winged Sphex (Cf. "Insect Life": chapters 6 to 9.—Translator's Note.) persists in descending into her burrow alone, after depositing at its edge the Cricket whom I maliciously at once remove. Her repeated discomfitures do not make her abandon the preliminary inspection of the home, an inspection which becomes quite useless when renewed for the tenth or twentieth time. The Mason-bee of the Walls shows us, under another form, a similar repetition of an act which is useless in itself, but which is the compulsory preface to the act that follows. When arriving with her provisions, the Bee performs a twofold operation of storing. First, she dives head foremost into the cell, to disgorge the contents of her crop; next, she comes out and at once goes in again backwards, to brush her abdomen and rub off the load of pollen. At the moment when the insect is about to enter the cell tail first, I push her aside gently with a straw. The second act is thus prevented. The Bee now begins the whole performance over again, that is to say, she once more dives head first to the bottom of the cell, though she has nothing left to disgorge, as her crop has just been emptied. When this is done, it is the belly's turn. I instantly push her aside again. The insect repeats its proceedings, still entering head first; I also repeat my touch of the straw. And this can go on as long as the observer pleases. Pushed aside at the moment when she is about to insert her abdomen into the cell, the Bee goes back to the opening and persists in going down head first to begin with. Sometimes, she descends to the bottom, sometimes only half-way, sometimes again she only pretends to descend, just bending her head into the aperture; but, whether completed or not, this action, for which there is no longer any motive, since the honey has already been disgorged, invariably precedes the entrance backwards to deposit the pollen. It is almost the movement of a machine whose works are only set going when the driving-wheel begins to revolve.