In spite of all my researches, I have never been able to discover the situation of the organ which produces the sound. But I have inst.i.tuted a new course of experiments on the subject, which are still unfinished.

Another problem still remains for solution. Why are the queens reared, according to M. Schirach's method, mute, whilst those bred in the time of swarming have the faculty of emitting a certain sound? What is the physical cause of this difference? At first I thought it might be ascribed to the period of life, when the worms that are to become queens receive the royal food. While hives swarm, the royal worms receive the food adapted for queens, from the moment of leaving the egg; those on the contrary, destined for queens, according to M. Schirach's method, receive it only the second or third day of their existence. It appears to me that this circ.u.mstance may have an influence on the different parts of organisation, and particularly on the organ of voice.

Experiment has not confirmed this conjecture. I constructed gla.s.s cells in perfect imitation of royal cells, that the metamorphosis of the worms into nymphs, and of the nymphs to queens, might be visible. These experiments are related in a preceding letter. Into one of these artificial cells we introduced the nymph of a worm, reared according to M. Schirach's method, twenty-four hours before it could naturally undergo its last metamorphosis; and we replaced the gla.s.s cell in the hive, that the nymph might have the necessary degree of heat. Next day, we had the satisfaction of seeing it divest itself of the spoil, and a.s.sume its ultimate figure. This queen was prevented from escaping from her prison; but we had contrived an aperture for her thrusting out her trunk, and that the bees might feed her. I expected that she would have been completely mute; but it was otherwise; for she emitted sounds similar to those already described, therefore my conjecture was erroneous.

I next conceived that the queen being restrained in her motions, and in her desire for liberty, was induced to emit certain sounds. All queens, in this new point of view, are equally capable of emitting the sound, but to induce them to it, they must be in a confined situation. In the natural state, the queens that come from workers are not a single instant in restraint; and, if they do not emit the sound, it is because nothing impels them to it. On the other hand, those produced at the time of swarming are induced to do so by the captivity in which they are kept. For my own part, I give little weight to this conjecture; and though I state it here, it is less with a view to claim merit than to put others on a plan of discovering something more probable.

I do not ascribe to myself the credit of having discovered the humming of the queen bee. Old authors speak of it. M. de Reaumur cites a Latin work published 1671, _Monarchia Femina_, by Charles Butler. He gives a very brief abstract of this naturalist's observations, who we easily see has exaggerated or rather disguised the truth, by mixing it with the most absurd fancies; but it is not the less evident that Butler has heard this peculiar humming of queens, and that he did not confound it with the confused humming sometimes heard in hives.

Fourthly. _The young queens conducting swarms from their native hive are still in a virgin state._ The day after, being settled in their new abode, they generally depart in quest of the males; and this is usually the fifth day of their existence as queens; for two or three pa.s.s in captivity, one in their native hive, and a fifth in their new dwelling.

Those queens that come from the worm of a worker, also pa.s.s five days in the hive before going in quest of males. So long as in a state of virginity, both are treated with indifference by the bees; but after returning with the external marks of fecundation, they are received by their subjects with the most distinguished respect. However, forty-six hours elapse after fecundation before they begin to lay. The old queen, which leads the first swarm in spring, requires no farther commerce with the males, for preservation of her fecundity. A single copulation is sufficient to impregnate all the eggs she will lay for at least two years.

_PREGNY, 8. September 1791._

FOOTNOTES:

{M} Schirach seems to have been aware of this fact.--T.

LETTER XI.

_THE SAME SUBJECT CONTINUED._

I have collected my chief observations on swarms in the two preceding letters; those most frequently repeated, and of which the uniformity of result leads me to apprehend no error. I have deduced what seem the most direct consequences; and in all the theoretical part, I have sedulously avoided going beyond facts. What is yet to be mentioned is more hypothetical, but it engrosses several curious experiments.

It has been demonstrated, that the princ.i.p.al motive of the young females departing when hives swarm, is their insuperable antipathy to each other. I have repeatedly observed that they cannot gratify their aversion, because the workers with the utmost care prevent them from attacking the royal cells. This perpetual opposition at length creates a visible inquietude, and excites a degree of agitation that induces them to depart. All the young queens are successively treated alike in hives that are to swarm. But the conduct of the bees towards the old queen, destined to conduct the first swarm, is very different. Always accustomed to respect fertile queens, they do not forget what they owe to her; they allow her the most uncontrouled liberty. She is permitted to approach the royal cells; and if she even attempts to destroy them, no opposition is presented by the bees. Thus her inclinations are not obstructed, and we cannot ascribe her flight, as that of the young queens, to the opposition she suffers. Therefore, I candidly confess myself ignorant of the motives of her departure.

Yet, on more mature reflection, it does not appear to me that this fact affords so strong an objection against the general rule as I had at first conceived. It is certain at least, that the old queens, as well as the young ones, have the greatest aversion to the individuals of their own s.e.x. This has been proved by the numerous royal cells destroyed. You will remember, Sir, that in my first observations on the departure of old queens, seven royal cells opened at one side were destroyed by the queen. If rain continues several days, the whole are destroyed; in this case, there is no swarm, which too often happens in our climate, where spring is generally rainy. Queens never attack cells containing an egg or a very young worm; but only when the worm is ready for transforming to a nymph, or when it has undergone its last metamorphosis.

The presence of royal cells with nymphs or worms near their change, also inspires old queens with the utmost horror or aversion; but here it would be necessary to explain why the queen does not always destroy them though it is in her power. On this point, I am limited to conjectures.

Perhaps the great number of royal cells in a hive at once, and the labour of opening the whole, creates insuperable alarm in the old queen.

She commences indeed with attacking her rivals; but, incapable of immediate success, her inquietude during this work becomes a terrible agitation. If the weather continues favourable, while she remains in this condition, she is naturally disposed to depart.

It may easily be understood, that the workers accustomed to respect their queen, whose presence is a real necessity to them, crowd after her; and the formation of the first swarm creates no difficulty in this respect. But you will undoubtedly ask, Sir, What motive can induce the workers to follow their queen from the hive, while they treat the young queens very ill, and, even in their most amicable moments, testify perfect indifference towards them. Probably it is to escape the heat to which the hive is then exposed. The extreme agitation of the females leads them to traverse the combs in all directions. They pa.s.s through groupes of bees, injure and derange them; they communicate a kind of delirium, and these tumultuous motions raise the temperature to an insupportable degree. We have frequently proved it by the thermometer.

In a populous hive it commonly stands between 92 and 97, in a fine day of spring; but during the tumult which precedes swarming, it rises above 104. And this is heat intolerable to bees. When exposed to it, they rush impetuously towards the outlets of the hive and depart. In general they cannot endure the sudden augmentation of heat, and in that case quit their dwelling; neither do those returning from the fields enter when the temperature is extraordinary.

I am certain, from direct experiments, that the impetuous courses of the queen over the combs, actually throws the workers into agitation; and I was able to ascertain it in the following manner. I wished to avoid a complication of causes. It was particularly important to learn, whether the queen would impart her agitation but not at the time of swarming.

Therefore I took two females still virgins, but capable of fecundation for above five days, and put one in a gla.s.s hive sufficiently populous; the other I put into a different hive of the same kind. Then I shut the hives in such a way that there was no possibility of their escape. The air had free circulation. I then prepared to observe the hives every moment that the fineness of the weather would invite both males and females to go abroad, for the purpose of fecundation. Next morning, the weather being gloomy, no male left the hive, and the bees were tranquil; but towards eleven of the following day, the sun shining bright, both queens began to run about seeking an exit from every part of their dwelling; and from their inability to find one, traversed the combs with the most evident symptoms of disquiet and agitation. The bees soon partic.i.p.ated of the same disorder; they crowded towards that part of the hive where the openings were placed; unable to escape they ascended with equal rapidity, and ran heedlessly over the cells until four in the afternoon. It is nearly about this time that the sun declining in the horizon recalls the males; queens requiring fecundation never remain later abroad. The two females became calmer, and tranquillity was in a short time restored. This was repeated several subsequent days with perfect similarity; and I am now convinced that there is nothing singular in the agitation of bees while swarming, but that they are always in a tumultuous state when the queen herself is in agitation.

I have but one fact more to mention. It has already been observed, that on losing the female, bees give the larvae of simple workers the royal treatment, and, according to M. Schirach, in five or six days they repair the loss of their queen. In this case there are no swarms. All the females leave their cells almost at the same moment, and after a b.l.o.o.d.y combat the throne remains with the most fortunate.

I can very well comprehend that the object of nature is to replace the lost queen; but as bees are at liberty to choose either the eggs or worms of workers, during the first three days of existence; to supply her place, why do they give the royal treatment to worms, all of nearly an equal age, and which must undergo their last metamorphosis almost at the same time? Since they are enabled to retain the young females in their cells, why do they allow all the queens, reared according to Schirach's method, to escape at once. By prolonging their captivity more or less, they would fulfil two most important objects at once, in repairing the loss of their females and preserving a succession of queens to conduct several swarms.

At first it was my opinion, that this difference of conduct proceeded from the difference of circ.u.mstances in which they found themselves situated. They are induced to make all their dispositions relative to swarming only when in great numbers, and when they have a queen occupied with her princ.i.p.al laying of male eggs; whereas, having lost their female, the eggs of drones are no longer in the combs to influence their instinct. They are in a certain degree restless and discouraged.

Therefore, after removing the queen from a hive, I thought of rendering all the other circ.u.mstances as similar as possible to the situation of bees preparing to swarm. By introducing a great many workers, I encreased the population to excess, and supplied them with combs of male brood in every stage. Their first occupation was to construct royal cells after Schirach's method, and to rear common worms with royal food.

They also began some stalact.i.te cells, as if the presence of the male brood had inspired them to it; but this they discontinued, as there was no queen to deposit her eggs. Finally, I gave them several close royal cells, taken indifferently from hives preparing to swarm. However, all these precautions were fruitless; the bees were occupied only with replacing their lost queen; they neglected the royal cells entrusted to their care; the included queens came out at the ordinary time, without being detained prisoners a moment; they engaged in several combats, and there were no swarms.

Recurring to subtleties, we may perhaps suggest a cause for this apparent contradiction. But the more we admire the wise dispositions of the author of nature, in the laws he has prescribed to the industry of animals, the greater reserve is necessary in admitting any theory adverse to this beautiful system, and the more must we distrust that facility of imagination from which we think by embellishment to elucidate facts.

In general, Naturalists who have long observed animals, and those in particular who have chose insects for their favourite study, have too readily ascribed to them our sentiments, our pa.s.sions, and even our intentions and designs. Incited to admiration, and disgusted perhaps by the contempt with which insects are treated, they have conceived themselves obliged to justify the consumption of time bestowed on this pursuit, and they have painted different traits of the industry of these minute animals, with the colours inspired by an exalted imagination. Nor is even the celebrated Reaumur to be acquitted of such a charge. He frequently ascribes combined intentions to bees; love, antic.i.p.ation, and other faculties of too elevated a kind. I think I can perceive that although he formed very just ideas of their operations, he would be well pleased that his reader should admit they were sensible of their own interests. He is a painter who by a happy interest flatters the original, whose features he depicts. On the other hand, Buffon unjustly considers bees as mere automatons. It was reserved for you, Sir, to establish the theory of animal industry on the most philosophical principles, and to demonstrate that those actions that have a moral appearance depend on an a.s.sociation of ideas _simply sensible_. It is not my object here to penetrate those depths, or to insist on the details.

But, on the whole, facts relative to the formation of swarms perhaps present more subjects of admiration than any other part of the history of bees. I think it proper to state, in a few words, the simplicity of the methods by which the wisdom of nature guides their instinct. It cannot allow them the slightest portion of understanding; it leaves them no precautions to be taken, no combination to be followed, no foresight to exercise, no knowledge to acquire. But having adapted their sensorium to the different operations with which they are charged, it is the impulse of pleasure which leads them on. She has therefore pre-ordained all that is relative to the succession of their different labours; and to each operation she has united an agreeable sensation.

Thus, when bees construct cells, watch over their larvae, and collect provisions, we must not seek for method, affection, or foresight. The only inducement must be sought for in some pleasing sensation attached to each of these operations. I address a philosopher; and as these are his own opinions applied to new facts, I believe my language will be easily understood. But I request my readers to peruse and to reflect on that part of your works which treats of the industry of animals. Let me add but another sentence. The inducement of pleasure is not the sole agent; there is another principle, the prodigious influence of which, at least with regard to bees, has. .h.i.therto been unknown, that is the sentiment of aversion which all females continually feel against each other, a sentiment whose existence is so fully demonstrated by my experiments, and which explains many important facts in the theory of swarms.

_PREGNY, 10. September 1791._

LETTER XII.

_ADDITIONAL OBSERVATIONS ON QUEENS THAT LAY ONLY THE EGGS OF DRONES, AND ON THOSE DEPRIVED OF THE ANTENNae._

In relating my first observations on queens that lay male eggs alone, I have proved that they lay them in cells of all dimensions indifferently, and even in royal cells. It is also proved that the same treatment is given to male worms hatched from eggs laid in the royal cells, as if they were actually to be transformed to queens; and I have added, that in this instance the instinct of the workers appeared defective. It is indeed most singular, that bees which know the worms of males so well when the eggs are laid in small cells, and never fail to give them a convex covering when about to transform to nymphs, should no longer recognise the same species of worms when the eggs are laid in royal cells, and treat them exactly as if they should change to queens. This irregularity depends on something I cannot comprehend.

In revising what is said on this subject, I observe still wanting an interesting experiment to complete the history of queens that lay only the eggs of drones. I had to investigate whether these females could themselves distinguish that the eggs they deposit in the royal cells would not produce queens. I have already observed that they do not endeavour to destroy these cells when close, and I thence concluded, that in general the presence of royal cells in their hive does not inspire them with the same aversion to females whose fecundation has been r.e.t.a.r.ded; but to ascertain the fact more correctly, it was essential to examine how the presence of a cell containing a royal nymph would affect a queen that had never laid any other than the eggs of drones.

This experiment was easy; and I put it in practice on the fourth of September, in a hive some time deprived of its queen. The bees had not failed to construct several royal cells for replacing their females. I chose this opportunity for supplying them with a queen, whose fecundation had been r.e.t.a.r.ded to the twenty-eighth day, and which laid none but the eggs of males. At the same time, I removed all the royal cells, except one that had been sealed five days. One remaining was enough to shew the impression it would make on the stranger queen introduced; had she endeavoured to destroy it; this, in my opinion, would have proved that she antic.i.p.ated the origin of a dangerous rival.

You must admit the use I make of the word antic.i.p.ate; it saves a long paraphrase; I feel the impropriety of it. If, on the contrary, she did not attack the cell I would thence conclude that the delay of fecundation, which deprived her of the power of laying workers eggs, had also impaired her instinct. This was the fact; the queen pa.s.sed several times over the royal cell, both the first and the subsequent day, without seeming to distinguish it from the rest. She quietly laid in the surrounding cells; notwithstanding the cares incessantly bestowed by the bees upon it, she never one moment appeared to suspect the danger with which the included royal nymph threatened her. Besides, the workers treated their new queen as well as they would have treated any other female. They were lavish of honey and respect, and formed those regular circles around her that seem an expression of homage.

Thus, independent of the derangement occasioned by r.e.t.a.r.ded impregnation, in the s.e.xual organs of queens, it certainly impairs their instinct. Aversion or jealousy is no longer preserved against their own s.e.x in the nymphine state, nor do they longer endeavour to destroy them in their cradles.

My readers will be surprised that queens whose fecundation has been r.e.t.a.r.ded, and whose fecundity is so useless to bees, should be so well treated and become as dear to them as females laying both kinds of eggs.

But I remember to have observed a fact more astonishing still. I have seen workers bestow every attention on a queen though sterile; and after her death treat her dead body as they had treated herself when alive, and long prefer this inanimate body to the most fertile queens I had offered them. This sentiment, which a.s.sumes the appearance of so lively an affection, is probably the effect of some agreeable sensation communicated to bees by their queen, independent of fertility. Those laying only the eggs of males probably excite the same sensation in the workers.

I now recollect that the celebrated Swammerdam somewhere observes, that when a queen is blind, sterile, or mutilated, she ceases to lay, and the workers of her hive no longer labour or make any collections, as if aware that it was now useless to work. He cites no experiment that led him to the discovery. Those made by myself have afforded some very singular results.

I frequently amputated the four wings of queens; and not only did they continue laying, but the same confederation of them was testified by the workers as before. Therefore, Swammerdam has no foundation for a.s.serting, that mutilated queens cease to lay. Indeed, from his ignorance of fecundation taking place without the hives, it is possible he cut the wings off virgin queens, and they, becoming incapable of flight, remained sterile from inability to seek the males in the air.

Thus, amputation of the wings does not produce sterility in queens.

I have frequently cut off one antennae to recognise a queen the more easily, and it was not prejudicial to her either in fecundity or instinct nor did it affect the attention paid to her by the bees. It is true, that as one still remained, the mutilation was imperfect; and the experiment decided nothing. But amputation of both antennae produced most singular effects. On the fifth of September, I cut both off a queen that laid the eggs of males only, and put her into the hive immediately after the operation. From this moment there was a great alteration in her conduct. She traversed the combs with extraordinary vivacity. Scarcely had the workers time to separate and recede before her; she dropped her eggs, without attending to deposit them in any cell. The hive not being very populous, part was without comb. Hither she seemed particularly earnest to repair, and long remained motionless. She appeared to avoid the bees; however, several workers followed her into this solitude, and treated her with the most evident respect. She seldom required honey from them, but, when that occurred, directed her trunk with an uncertain kind of feeling, sometimes on the head and sometimes on the limbs of the workers, and if it did reach their mouths, it was by chance. At other times she returned upon the combs, then quitted them to traverse the gla.s.s sides of the hive: and always dropped eggs during her various motions. Sometimes she appeared tormented with the desire of leaving her habitation. She rushed towards the opening, and entered the gla.s.s tube adapted there; but the external orific being too small, after fruitless exertion, she returned. Notwithstanding these symptoms of delirium, the bees did not cease to render her the same attention as they ever pay to their queens, but this one received it with indifference. All that I describe appeared to me the consequence of amputating the antennae.

However, her organization having already suffered from r.e.t.a.r.ded fecundation, and as I had observed her instinct in some degree impaired, both causes might possibly concur in producing the same effect. To distinguish properly what belonged to the privation of the antennae, a repet.i.tion of the experiment was necessary, in a queen otherwise well organised, and capable of laying both kinds of eggs.

This I did on the sixth of September. I amputated both the antennae of a female which had been several months the subject of observation, and being of great fecundity had already laid a considerable number of workers eggs, and those of males. I put her into the same hive where the queen of the preceding experiment still remained, and she exhibited precisely the same marks of delirium and agitation, which I think it needless to repeat. I shall only add, that to judge better of the effect produced by privation of the antennae, on the industry and instinct of bees, I attentively considered the manner in which these two mutilated queens treated each other. You cannot have forgot, Sir, the animosity with which queens, possessing all their organs, combat, on which account it became extremely interesting to learn whether they would experience the same reciprocal aversion after losing their antennae. We studied these queens a long time; they met several times in their courses, and without exhibiting the smallest resentment. This last instance is, in my opinion, the most complete evidence of a change operated in their instinct.

Another very remarkable circ.u.mstance, which this experiment gave me occasion to observe, consists in the good reception given by the bees to the stranger queen, while they still preserved the first. Having so often seen the symptoms of discontent that a plurality of queens occasions, after having witnessed the cl.u.s.ters formed around these supernumerary queens to confine them, I could not expect they would pay the same homage to a second mutilated one they still testified towards the first. Is it because after losing the antennae, these queens have no more any characteristic which distinguishes the one from the other?

I was the more inclined to admit this conjecture from the bad reception of a third fertile queen preserving her antennae, which was introduced into the same hive. The bees seized, bit her, and confined her so closely, that she could hardly breath or move. Therefore, if they treat two females deprived of antennae in the same hive equally well, it is probably because they experience the same sensation from these two females, and want the means of longer distinguishing them from each other.

From all this, I conclude, that the antennae are not a frivolous ornament to insects, but, according to all appearance, are the organs of touch or smell. Yet I cannot affirm which of these senses reside in them. It is not impossible that they are organised in such a manner as to fulfil both functions at once.