You will admit, I think, that these proofs of the resources of the architectural instinct of bees are truly admirable. If, in the case of the substitution of mitys for the first range of waxen cells, this procedureinvariablytook place ineverybee-hive at afixedperiod—when, for example, the combs are two-thirds filled with honey—it would be less surprising: but there is nothing of this invariable character about it. It does not, as Huber expressly informs us[782], occur at any marked and regular period, but appears to depend on several circumstances not always combined. Sometimes the bees content themselves with bordering the sides of the upper cells with propolis alone, without altering their form or giving them greater thickness. And it is not less remarkable that, from the instances last cited, it appears that they are not confined to one kind of cement for strengthening and supporting their combs, but avail themselves ofpropolis, wax, or a mixture of both, as circumstances direct.
Not to weary you with examples of the modifications of instinct we are considering, I shall introduce but three more:—the first, of the mode in which bees extend the dimensions of an old comb; the second, of that which they adopt in constructing the male cells and connecting them with the smaller cells of workers; and the last, of the plan pursued by them when it becomes necessary to bend their combs.
You must have observed that a comb newly made becomes gradually thinner at its edges, the cells there, on each side, progressively decreasing in length: but in time these marginal cells, as they are wanted for the purposes of the hive, are elongated to the depth of the rest. Now suppose bees, from an augmentation of the size of their hive, to have occasion to extend their combs either in length or breadth, the process which they adopt is this: They gnaw away the tops of the marginal cells until the combs have resumed their original lenticular form, and then construct upon their edges the pyramidal lozenge-shaped bottoms of cells, upon which the hexagonal sides are subsequently raised, as in their operation of cell-building. This course of proceeding is invariable: they never extend a comb in any direction whatever, without having first made its edges thinner, diminishing its thickness in a portion sufficiently large to leave no angular projection.—Huber observes, and with reason, in relating this surprising law which obliges bees partially to demolish the cells situated upon the edges of the combs, that it deserves a more close examination than he found himself competent to give it: for, if we may toa certain point form a conception of the instinct which leads these animals to employ their art of building cells, yet how can we conceive of that which in particular circumstances forces them to act in an opposite direction, and determines them todemolishwhat they have so laboriously constructed[783]?
Drones, or male bees, are more bulky than the workers; and you have been told, in speaking of the habitations of insects, that the cells which bees construct for rearing the larvæ of the former, are larger than those destined for the education of the larvæ of the latter. The diameter of the cells of drones is always 3-1/3 lines (or twelfths of an inch); that of those of workers 2-2/5 lines: and these dimensions are so constant in their ordinary cells, that some authors have thought they might be adopted as an universal and invariable scale of measure, which would have the great recommendation of being every where at hand, and at all events would be preferable to ourbarley-corns. Several ranges of male cells, sometimes from thirty to forty, are usually found in each comb, generally situated about the middle. Now as these cells are not isolated, but form a part of the entire comb, corresponding on its two faces—by what art is it that the bees unite hexagonal cells of a small, with others of a larger diameter, without leaving any void spaces, and without destroying the uniformity and regularity of the comb? This problem would puzzle an ordinary artist, but is easily solved by the resources of the instinct of our little workmen.
When they are desirous of constructing the cells of males below those of workers, they form several rangesof intermediate or transition cells, of which the diameter augments progressively, until they have reached that range where the male cells commence; and in the same manner, when they wish to revert to the modelling of the cells of workers, they pass by a gradually decreasing gradation to the ordinary diameter of the cells of this class.—We commonly meet with three or four ranges of intermediate cells before coming to those of males; the first ranges of which participate in some measure in the irregularity of the former.
But it is upon the construction of thebottomsof the intermediate ranges of cells that this variation of their architecture chiefly hinges. The bottoms of the regular cells of bees are, as you are aware, composed ofthreeequal-sized rhomboidal pieces; and the base of a cell on one side of the comb is composed of portions of the bases ofthreecells on the other; but the bottoms of the intermediate cells in question (though their orifices are perfectly hexagonal) are composed offourpieces, of which two are hexagonal and two rhomboidal; and each, instead of corresponding with three cells on the opposite side, corresponds withfour. The size and the shape of the four pieces composing the bottom, vary; and these intermediate cells, a little larger than the third part of the three opposite cells, comprise in their contour a portion of the bottom of the fourth cell. Just below the last range of cells with regular pyramidal bottoms, are found cells with bottoms of four pieces, of which three are very large, and one very small, and this last is a rhomb. The two rhombs of the transition cells are separated by a considerable interval; but the two hexagonal pieces are adjacent and perfectly alike. A cell lower, we perceive thatthe two rhombs of the bottom are not so unequal: the contour of the cell has included a greater portion of the opposite fourth cell. Lastly, we find cells in pretty considerable number, of which the bottom is composed of four pieces perfectly regular—namely, two elongated hexagons and two equal rhombs, but smaller than those of the pyramidal bottoms. In proportion as we remove our view from the cells with regular tetrahedral bottoms, whether in descending or from right to left, we see that the subsequent cells resume their ordinary form; that is to say, that one of their rhombs is gradually lessened until it finally disappears entirely; and the pyramidal form re-exhibits itself, but on a larger scale than in the cells at the top of the comb. This regularity is maintained in a great number of ranges, namely, those consisting of male cells; afterwards the cells diminish in size, and we again remark the tetrahedral bottoms just described, until the cells have once more resumed the proper diameter of those of workers.
It is, then, by encroaching in a small degree upon the cells of the other face of the comb, that bees at length succeed in giving greater dimensions to their cells; and the graduation of the transition cells being reciprocal on the two faces of the comb, it follows that on both sides each hexagonal contour corresponds with four cells.—When the bees have arrived at any degree of this mode of operating, they can stop there and continue to employ it in several consecutive ranges of cells: but it is to the intermediate degree that they appear to confine themselves for the longest period, and we then find a great number of cells of which the bottoms of four pieces are perfectly regular. They might, then, construct the wholecomb on this plan, if their object were not to revert to the pyramidal form with which they set out.—In building the male cells, the bees begin their foundation with a block or mass of wax thicker and higher than that employed for the cells of workers, without which it would be impracticable for them to preserve the same order and symmetry in working on a larger scale.
Irregularities (to use the language of Huber, from whom the above details are abstracted,) have often been observed in the cells of bees. Reaumur, Bonnet and other naturalists cite them as so many examples of imperfections. What would have been their astonishment if they had been aware that part of these anomalies arecalculated; that there exists as it were a moveable harmony in the mechanism by which the cells are composed! If, in consequence of the imperfection of their organs or of their instruments, bees occasionally constructed some of their cells unequal, or of parts badly put together, it would still manifest some talent to be able to repair these defects, and to compensate one irregularity by another: but it is far more astonishing that they know how to quit their ordinary routine when circumstances require that they should build male cells; that they should be instructed to vary the dimensions and the shape of each piece so as to return to a regular order; and that, after having constructed thirty or forty ranges of male cells, they again leave the regular order on which these were formed, and arrive by successive diminutions at the point from which they set out. How should these insects be able to extricate themselves from such a difficulty—from such a complicated structure? how pass from the little to the great, from a regular plan to an irregular one,and again resume the former? These are questions which no known system can explain[784].
Here again, as observed in a former instance, the wonder would be less, ifeverycomb contained acertainnumber of transition and of male cells, constantly situated inoneand thesamepart of it: but this is far from being the case. The event which alone, at whatever period it may happen, seems to determine the bees to construct male cells, is the oviposition of the queen. So long as she continues to lay the eggs of workers not a male cell is founded; but as soon as she is about to lay male eggs, the workers seem aware of it, and you then see them form their cells irregularly, impart to them by degrees a greater diameter, and at length prepare suitable ranges of cradles for all the male race[785].—You must perceive how absurd it would be to refer this astonishing variation of instinct to any mere change in thesensationsof the bees; and to what far-fetched and gratuitous suppositions we must be reduced, if we adopt any such explanation. We can but refer it to an instinct of which we know nothing; and so referring it, can we help exclaiming with Huber, "Such is the grandeur of the views and of the means of ordaining wisdom, that it is not by a minute exactness that she marches to her end, but proceeds from irregularity to irregularity, compensating one by another: the admeasurements are made on high, the apparent errors appreciated by a divine geometry; and order often results from partial diversity. This is not the first instance which science has presented to us of preordained irregularities which astonish our ignorance,and are the admiration of the most enlightened minds: So true it is, that the more we investigate the general as well as particular laws of this vast system, the more perfection does it present[786]."
It is observed by M. P. Huber, in his appendix to the account of his father's discoveries relative to the architecture of bees, that in general the form of the prisms or tubes of the cells is more essential than that of their bottoms, since the tetrahedral-bottomed transition cells, and even those cells which being built immediately upon wood or glass, were entirely without bottoms, still preserved their usual shape of hexagonal prisms. But a remarkable experiment of the elder Huber shows that bees can alter even the form of their cells when circumstances require it, and that in a way which one would not have expected.
Having placed in front of a comb which the bees were constructing, a slip of glass, they seemed immediately aware that it would be very difficult to attach it to so slippery a surface: and instead of continuing the comb in a straight line, theybent it at a right angle, so as to extend beyond the slip of glass, and ultimately fixed it to an adjoining part of the wood-work of the hive which the glass did not cover. This deviation, if the comb had been a mere simple and uniform mass of wax, would have evinced no small ingenuity; but you will bear in mind that a comb consists on each side, or face, of cells having between them bottoms in common: and if you take a comb, and having softened the wax by heat, endeavour to bend it in any part at a right angle, you willthen comprehend the difficulties which our little architects had to encounter. The resources of their instinct, however, were adequate to the emergency. They made the cells on theconvexside of the bent part of the comb muchlarger, and those on theconcaveside muchsmallerthan usual; the former having three or four times the diameter of the latter. But this was not all. As the bottoms of the small and large cells were as usual common to both, the cells were not regular prisms, but the small ones considerably wider at the bottom than at the top, and conversely in the large ones!—What conception can we form of so wonderful a flexibility of instinct? How, as Huber asks, can we comprehend the mode in which such a crowd of labourers, occupied at the same time on the edge of the comb, could agree to give to it the same curvature from one extremity to the other; or how they could arrange together to construct on one face cells so small, while on the other they imparted to them such enlarged dimensions?—And how can we feel adequate astonishment that they should have the art of making cells of such different sizes correspond[787]?
After this long but I flatter myself not wholly uninteresting enumeration, you will scarcely hesitate to admit that insects, and of these the bee pre-eminently, are endowed with a much more exquisite and flexible instinct than the larger animals. But you may be here led to ask, Can all this be referred to instinct? Is not this pliability to circumstances—this surprising adaptation of means for accomplishing an end—rather the result ofreason?
You will not doubt my allowing the appositeness of this question, when I frankly tell you, that so strikingly do many of the preceding facts seem at first view the effect of reason, that in my original sketch of the letter you are now reading, I had arranged them as instances of this faculty. But mature consideration has convinced me (though I confess the subject has great difficulties) that this view was fallacious; and that though some circumstances connected with these facts may, as I shall hereafter show, be referable to reason, the facts themselves can only be consistently explained by regarding them as I have here done, as examples of variations of particular instincts:—and this on two accounts.
In the first place, these variations, however singular, arelimitedin their extent: all bees are, and have always been, able to avail themselves of a certain number, but not to increase that number. Bees cemented their combs when becoming heavy, to the top of the hive, with mitys, in the time of Aristotle and Pliny as they do now; and there is every reason to believe that then, as now, they occasionally varied their procedures, by securing them with wax or with propolis only, either added to the upper range of cells, or disposed in braces and ties to the adjoining combs. But if in thus proceeding they were guided by reason, why not under certain circumstances adoptothermodes of strengthening their combs? Why not, when wax and propolis are scarce, employmud, which they might see the martin avail herself of so successfully? Or why should it not come into the head of some hoary denizen of the hive, that a little of themortarwith which his careful master plasters the crevices between his habitation and its stand, might answer the endof mitys? "Si seulement ils élevoient une fois des câbanes quarrées," (says Bonnet when, speaking as to what faculty the works of the beaver are to be referred,) "mais ce sont éternellement des câbanes rondes ou ovales[788]:"—and so we might say of the phenomena in question:—Show us butoneinstance of bees having substituted mud or mortar for mitys, pissoceros, or propolis, or wooden props for waxen ties, and there could be no doubt of their being here guided by reason. But since no such instance is on record; since they are still confined to the same limits—however surprising the range of these limits—as they were two thousand years ago; and since the bees emerged from their pupæ but a few hours before, will set themselves as adroitly to work and pursue their operations as scientifically as their brethren, who can boast the experience of a long life of twelve months duration;—we must still regard these actions as variations of instinct.
In the second place, no degree of reason that we can with any share of probability attribute to bees, could be competent to the performance of labours so complicated as those we have been considering, and which if the result of reason, would involve the most extensive and varied knowledge in the agents. Suppose a man to have attained by long practice the art of modelling wax into a congeries of uniform hexagonal cells, with pyramidal bottoms composed each of three rhombs, resembling the cells of workers among bees. Let him now be set to make a congeries of similar but larger cells (answering to the male cells), and unite these with the former by other hexagonal cells, so that there should be no disruptionin the continuity or regularity of the whole assemblage, and no vacant intervals or patching at the junctions either of the tubes or the bottoms of the cells;—and you would have set him no very easy task—a task, in short, which it may be doubted if he would satisfactorily perform in a twelvemonth, though gifted with a clear head and a competent store of geometrical knowledge, and which, if destitute of these requisites, it may be safely asserted that he would never perform at all. How then can we imagine it possible that this difficult problem, and others of a similar kind, can be so completely and exactly solved by animals of which some are not two days old, others not a week, and probably none a year? The conclusion is irresistible—it is notreasonbutinstinctthat is their guide.
The second head under which I proposed contrasting the instincts of insects with those of the larger animals, was that of theirnumberin the same individual.—In the latter this is for the most part very limited, not exceeding (if we omit those common to almost all animated beings) eight or ten distinct instincts. Thus in the common duck, one instinct leads it at its birth from the egg to rush to the water; another to seek its proper food; a third to pair with its mate; a fourth to form a nest; a fifth to sit upon its eggs till hatched; a sixth to assist the young ducklings in extricating themselves from the shell; and a seventh to defend them when in danger until able to provide for themselves: and it would not be easy, as far as my knowledge extends, to add many more distinct instinctive actions to the enumeration, or to adduce many species of the superior classes of animals, endowed with a greater number.
But how vastly more manifold are the instincts of the majority of insects! It is not necessary to insist upon those differences which take place in the same insect in its different states, leading it to select one kind of food in the larva, and another in the perfect state; to defend itself in one mode in the former, and in another in the latter, &c.—because, however remarkable these variations, they may be referred with great plausibility to those striking changes in the organic structure of the animal, which occur at the two periods of its existence. It is to the number of instincts observable in the same individual of many insects in their perfect state that I now confine myself; and as the most striking example of the whole I shall select the hive-bee,—begging you to bear in mind that I do not mean to include those exhibited by the queen, the drones, or even those of the workers, termed by Hubercirières(wax makers); but only to enumerate those presented by that portion of the workers, termed by Hubernourricesorpetites abeilles(nurses), upon whom, as you have been before told[789], with the exception of making wax, laying the foundation of the cells, and collecting honey for being stored, the principal labours of the hive devolve. It will be these individuals alone that I shall understand by the termbees, under the present head: and though the other inhabitants of the hive may occasionally concur in some of their actions and labours, yet it is obvious that so many as are those in whichtheydistinctly take part, so many instincts must we regard them as endowed with.
To begin, then, with the formation of the colony:—By one instinct bees are directed to send out scouts previouslyto their swarming, in search of a suitable abode[790]; and by another, to rush out of the hive after the queen that leads forth the swarm, and follow wherever she bends her course. Having taken possession of their new abode, whether of their own selection or prepared for them by the hand of man, a third instinct teaches them to cleanse it from all impurities[791]; a fourth to collect propolis, and with it to stop up every crevice except the entrance; a fifth to ventilate the hive for preserving the purity of the air; and a sixth to keep a constant guard at the door[792].
In constructing the houses and streets of their new city, or the cells and combs, there are probably several distinct instincts exercised; but not to leave room for objection, I shall regard them as the result of one only: yet the operations of polishing the interior of the cells, and soldering their angles and orifices with propolis, which are sometimes not undertaken for weeks after the cells are built[793]; and the obscure but still more curious one of varnishing them with the yellow tinge observable in old combs;—seem clearly referable to at least two distinct instincts. The varnishing process is so little connected with that of building, that, though it takes place in some combs in three or four days, it does not in others for several months, though both are equally employed for the same uses[794]. Huber ascertained by accurate experiment that this tinge is not owing to the heat of the hives; to any vapours in the air which they include; to any emanations from the wax or honey; nor to the deposition of this last in the cells; but he inclinesto think it is occasioned by a yellow matter which the bees seem to detach from their mandibles, and to apply to the surface which they are varnishing, by repeated strokes of these organs and of the fore feet[795].
In their out-of-door operations several distinct instincts are concerned. By one they are led to extract honey from the nectaries of flowers; by another to collect pollen after a process involving very complicated manipulations, and requiring a singular apparatus of brushes and baskets; and that must surely be considered a third, which so remarkably and beneficially restricts each gathering to the same plant[796]. It is clearly a distinct instinct which inspires bees with such dread of rain, that even if a cloud pass before the sun, they return to the hive in the greatest haste[797]; and that seems to me not less so, which teaches them to find their way back to their home after the most distant and intricate wanderings. When bees have found the direction in which their hive lies, Huber says they fly to it with an extreme rapidity, and as straight as a ball from a musket[798]: and if their hives were always in open situations, one might suppose, as Huber seems inclined to think, that it is by their sight they are conducted to them. But hives are frequently found in small gardens embowered in wood; and in the midst of villages surrounded and interspersed with trees and buildings, so as to make it impossible that they can be seen from a distance. If you had been with me in 1815, in the famous Pays de Waes in Flanders—where the country is a perfect flat, and the inhabitants so enamoured either of the beauty or profit of trees, that theirfields, which are rarely above three acres in extent, areconstantlysurrounded with a double row, making the whole district one vast wood—you would have pitied the poor bees if reduced to depend on their own eye-sight for retracing the road homeward. In vain during my stay at St. Nicholas I sallied out at every outlet to try to gain some idea of the extent and form of the town. Trees—trees—trees—still met me, and intercepted the view in every direction; and I defy any inhabitant bee of this rural metropolis, after once quitting its hive, ever to gain a glimpse of it again until nearly perpendicularly over it. The bees, therefore, of the Pays de Waes, and consequently all other bees, must be led to their abodes by instinct, as certainly as it is instinct that directs the migrations of birds or of fishes, or domestic quadrupeds to find out their homes from inconceivable distances[799].—When they have reached the hive, another instinct leads them to regurgitate into the extended proboscis of their hungry companions who have been occupied at home, a portion of the honey collected in the fields; and another directs them to unload their legs of the masses of pollen, and to store it in the cells for future use.
Several distinct instincts, again, are called into action in the important business of feeding the young brood. One teaches them to swallow pollen, not to satisfy the calls of hunger, but that it may undergo in their stomach an elaboration fitting it for the food of the grubs; and another to regurgitate it when duly concocted, and to administer it to their charge, proportioning the supply to the age and condition of the recipients. A third informs them when the young grubs have attained their full growth, and directs them to cover their cells with a waxen lid, convex in the male cells, but nearly flat in those of workers; and by a fourth, as soon as the young bees have burst into day, they are impelled to clean out the deserted tenements and to make them ready for new occupants.
Numerous as are the instincts I have already enumerated, the list must yet include those connected with that mysterious principle which binds the working bees of a hive to their queen:—the singular imprisonment in which they retain the young queens that are to lead off a swarm, until their wings be sufficiently expanded toenable them to fly the moment they are at liberty, gradually paring away the waxen wall that confines them to their cell to an extreme thinness, and only suffering it to be broken down at the precise moment required;—the attention with which, in these circumstances, they feed the imprisoned queen by frequently putting honey upon her proboscis, protruded from a small orifice in the lid of her cell;—the watchfulness with which, when at the period of swarming more queens than one are required, they place a guard over the cells of those undisclosed, to preserve them from the jealous fury of their excluded rivals;—the exquisite calculation with which they invariably release theoldestqueens the first from their confinement;—the singular love of monarchical dominion, by which, when two queens in other circumstances are produced, they are led to impel them to combat until one is destroyed;—the ardent devotion which binds them to the fate and fortunes of the survivor;—the distraction which they manifest at her loss, and their resolute determination not to accept of any stranger until an interval has elapsed sufficiently long to allow of no chance of the return of their rightful sovereign;—and (to omit a further enumeration) the obedience which in the utmost noise and confusion they show to her well-known hum.
I have now instanced at least thirty distinct instincts with which every individual of the nurses amongst the working-bees is endowed: and if to the account be added their care to carry from the hive the dead bodies of any of the community; their pertinacity in their battles, in directing their sting at those parts only of the bodies of their adversaries which are penetrable by it; theirannual autumnal murder of the drones, &c. &c.—it is certain that this number might be very considerably increased, perhaps doubled.
At the first view you will be inclined to suspect some fallacy in this enumeration, and that this variety of actions ought to be referred rather to some general principle, capable of accommodating itself to different circumstances, than to so many different kinds of instinct. But to what principle? Not to reason, the faculty to which we assign this power of varying accommodation. All the actions above adduced come strictly under the description of instinctive actions, being all performed by every generation of bees since the creation of the world, and as perfectly a day or two after their birth as at any subsequent period. And as the very essence of instinct consists in the determinate character of the actions to which it gives birth, it is clear that every distinctly different action must be referred to a distinct instinct. Few will dispute that the instinct which leads a duck to resort to the water is a different instinct from that which leads her to sit upon her eggs; for the hen though endowed with one is not with the other. In fact, they are as distinct and unconnected as the senses of sight and smell; and it appears to me that it would be as contrary to philosophical accuracy of language, in the former case to call the two instincts modifications of each other, as in the latter so to designate the two senses; and as we say that a deaf and blind man has fewer senses than other men, so (strictly) we ought not to speak of instinct as one faculty (though to avoid circumlocution I have myself often employed this common mode of expression), or say that one insect has a greater or less share of instinct thananother, but more or fewerinstincts.—That it is not always easy to determine what actions are to be referred to a distinct instinct and what to a modification of an instinct, I am very ready to admit; but this is no solid ground for regarding all instincts as modifications of some one principle. It is often equally difficult to fix the limits between instinct and reason; but we are not on this account justified in deeming them the same.
This multitude of instincts in the same individual, becomes more wonderful when considered in another point of view. Were they constantly to follow each other in regular sequence, so that each bee necessarily first began to build cells, then to collect honey, next pollen, and so on, we might plausibly enough refer them to some change in the sensations of the animal, caused by alterations in the structure and gradual development of its organs, in the same way as on similar principles we explain the sexual instincts of the superior tribes. But it is certain that no such consecutive series prevails. The different instincts of the bee are called into action in an order regulated solely by the needs of the society. If combs be wanted, no bee collects honey for storing until they are provided[800]: and if, when constructed, any accident injure or destroy them, every labour is suspended until the mischief is repaired or new ones substituted[801]. When the crevices round the hive are effectually secured with propolis, the instinct directing the collection of this substance lies dormant: but transfer the bees to a new hive which shall require a new luting, and it is instantly re-excited. But these instances aresuperfluous. Every one knows that at the same moment of time the citizens of a hive are employed in the most varied and opposite operations. Some are collecting pollen; others are in search of honey; some busied at home in the first construction of the cells; others in giving them their last polish; others in ventilating the hive; others again in feeding the young brood and the like.
Now, how are we to account for this regularity of procedure—this undeviating accuracy with which the precise instinct wanted is excited—this total absence of all confusion in the employment by each inhabitant of the hive, of that particular instinct out of so many which the good of the community requires? No thinking man ever witnesses the complexness and yet regularity and efficiency of a great establishment, such as the Bank of England, or the Post-office, without marvelling that even human reason can put together with so little friction and such slight deviations from correctness, machines whose wheels are composed not of wood and iron, but of fickle mortals of a thousand different inclinations, powers, and capacities. But if such establishments be surprising even with reason for their prime mover, how much more so is a hive of bees whose proceedings are guided by their instincts alone! We can conceive that the sensations of hunger experienced on awaking in the morning should excite into action their instinct of gathering honey. But all are hungry: yet all do not rush out in search of flowers. Whatsensationis it thatdetainsa portion of the hive at home, unmindful of the gnawings of an empty stomach, busied in domestic arrangements, until the return of their roving companions? Of thosethat fly abroad, what conception can we form of the cause which, while one set is gathering honey or pollen, leads another company to load their legs with pellets of propolis? Are we to say that the instinct of the former is excited by one sensation, that of the latter by another? But why should one sensation predominate in one set of bees, while another takes the lead in a second?—or how is it that these different instincts are called up precisely in the degree which the actual and changing state of things in the hive requires?—Of those which remain at home, what is it that determines in one party the instinct of building cells to prevail; in another that of ventilating the hive; in a third that of feeding the young brood? For my own part, I confess that the more I reflect on this subject, and contrast the diversity of the means with the regularity and uniformity of the end, the more I am lost in astonishment. The effects of instinct seem even more wonderful than those of reason, in the same manner as the consentaneous movements of a mighty and divided army, which, though under the command of twenty generals and from the most distant quarters, should meet at the assigned spot at the very hour fixed upon, would be more surprising than the steam-moved operations, however complex, of one of Boulton's mints.
For the sake of distinctness and compression, I have confined myself in considering the number of the instincts of individual insects to a single species, the bee; but if the history of other societies of these animals—wasps, ants, &c. detailed in my former letters, be duly weighed, it will be seen that they furnish examples of the variety in question fully as striking. These corroborating proofs I shall leave to your own inference, andproceed to the third head, under which I proposed to consider the instincts of insects—that of their extraordinary development.
The development of some of the instincts of the larger animals, such as those of sex, is well known to depend upon their age and the peculiar state of the bodily organs; and to this, as before observed, the succession of different instincts in the same insect, in its larva and perfect state, is closely analogous. But what I have now in view is thatextraordinary developmentof instinct, which is dependent not upon the age or any change in the organization of the animal, but upon external events—which in individuals of thesamespecies, age, and structure, in some circumstances slumbers unmoved, but may in others be excited to the most singular and unlooked-for action. In illustrating this property of instinct, which, as far as I am aware, is not known to occur in any of the larger animals, I shall confine myself as before to the hive-bee; the only insect, indeed, in which its existence has been satisfactorily ascertained, though it is highly probable that other species living in societies may exhibit the same phenomenon.
Several of the facts occurring in the history of bees might be referred to this head; but I shall here advert only to the treatment of the drones by the workers under different circumstances, and to the operations of the latter consequent upon the irretrievable loss of the queen—facts which have been before stated to you, but to the principal features of which my present argument makes it necessary that I should again direct your attention.
If a hive of bees be this year in possession of a queenduly fertilized, and consequently sure the next season of a succession of males, all the drones, as I have before stated[802], towards the approach of winter are massacred by the workers with the most unrelenting ferocity. To this seemingly cruel course they are doubtless impelled by an imperious instinct; and as it is regularly followed in every hive thus circumstanced, it would seem at the first view to be an impulse as intimately connected with the organization and very existence of the workers, and as incapable of change, as that which leads them to build cells or to store up honey. But this is far from being the case. However certain the doom of the drones this autumn, if the hive be furnished with a duly-fertilized queen, their undisturbed existence over the winter is equally sure if the hive have lost its sovereign, or her impregnation have been so retarded as to make a succession of males in the spring doubtful. In such a hive the workers do not destroy a single drone, though the hottest persecution rages in all the hives around them.
Now, how are we to explain this difference of conduct? Are we to suppose that the bees know and reason upon this alteration in the circumstances of their community—that they infer the possibility of their entire extinction if the whole male stock were destroyed when without a queen—and that thus influenced by a wise policy they restrain the fury they would otherwise have exercised? This would be at once to make them not only gifted with reason, but endowed with a power of looking before and after, and a command over the strongest natural propensities, superior to what could be expected in a similar case even from a society of men;and is obviously unwarrantable. The only probable supposition is, clearly, that a new instinct is developed suited to the extraordinary situation in which the community stands, leading them now to regard with kindness the drones, for whom otherwise they would have felt the most violent aversion.
In this instance, indeed, it would perhaps be more strictly correct to say (which, however, is equally wonderful) that the old instinct was extinguished; but in the case of the loss of a queen, to which I am next to advert, which is followed by positive operations, the extraordinary development of a new and peculiar instinct is indisputable.
In a hive which no untoward event has deprived of its queen, the workers take no other active steps in the education of her successors—those of which one is to occupy her place when she has flown off at the head of a new swarm in spring—than to prepare a certain number of cells of extraordinary capacity for their reception while in the egg, and to feed them when become grubs with a peculiar food until they have attained maturity. This, therefore, is their ordinary instinct; and it may happen that the workers of a hive may have no necessity for a long series of successive generations to exercise any other. But suppose them to lose their queen. Far from sinking into that inactive despair which was formerly attributed to them, after the commotion which the rapidly-circulated news of their calamity gave birth to has subsided, they betake themselves with an alacrity from which man when under misfortune might deign to take a lesson, to the active reparation of their loss. Several ordinary cells,as was before related at large[803], are without delay pulled down, and converted into a variable number of royal cells capacious enough for the education of one or more queen-grubs selected out of the unhoused working grubs—which in this pressing emergency are mercilessly sacrificed—and fed with the appropriate royal food to maturity. Thus sure of once more acquiring a head, the hive return to their ordinary labours, and in about sixteen days one or more queens are produced; one of which, after being indebted to fortune for an elevation as singular as that of Catherine the First of Russia, steps into day and assumes the reins of state.
To this remarkable deviation from the usual procedures of the community, the observations above made in the case of the drones must be applied. We cannot account for it by conceiving the working bees to be acquainted with the end which their operations have in view. If we suppose them toknowthat the queen and working-grubs are originally the same, and that to convert one of the latter into the former it is only necessary to transfer it to an apartment sufficiently spacious and to feed it with a peculiar food, we confer upon them a depth of reason to which Prometheus, when he made his clay man, had no pretensions—an original discovery, in short, to which man has but just attained after some thousand years of painful research, having escaped all the observers of bees from Aristomachus, to Swammerdam and Reaumur of modern times. We have no other alternative, then, but to refer this phenomenon to the extraordinarydevelopment of a new instinct suited for the exigency, however incomprehensible to us the manner of its excitement may appear.
II. Such, then, are the exquisiteness, the number, and the extraordinary development of the instincts of insects. But is instinct thesoleguide of their actions? Are they in every case the blind agents of irresistible impulse? These queries, I have already hinted, cannot in my opinion be replied to in the affirmative; and I now proceed to show, that though instinct is the chief guide of insects, they are endowed also with no inconsiderable portion ofreason.
Some share of reason is denied by few philosophers of the present day to the larger animals. But its existence has not generally (except by those who reject instinct altogether) been recognised in insects: probably on the ground that, as the proportions of reason and of instinct seem to co-exist in an inverse ratio, the former might be expected to be extinct in a class in which the latter is found in such perfection. This rule, however, though it may hold good in man, whose instincts are so few and imperfect, and whose reason is so pre-eminent, is far from being confirmed by an extended survey of the classes of animals generally. Many quadrupeds, birds, and fishes, with instincts apparently not very acute, do not seem to have their place supplied by a proportionably superior share of reason: and insects, as I think the facts I have to adduce will prove, though ranking so low in the scale of creation, seem to enjoy as great a degree of reason as many animals of the superior classes, yet in combination with instincts much more numerous and exquisite.
I must premise, however, that in so perplexed and intricate a field, I am sensible how necessary it is to tread with caution. A far greater collection of facts must be made, and the science of metaphysics generally be placed on a more solid foundation than it now can boast, before we can pretend to decide, in numerous cases, which of the actions of insects are to be deemed purely instinctive, and which the result of reason. What I advance, therefore, on this head, I wish to be regarded rather as conjectures, that, after the best consideration I am able to give to a subject so much beyond my depth, seem to me plausible, than as certainties to which I require your implicit assent.
That reason has nothing to do with the major part of the actions of insects is clear, as I have before observed, from the determinateness and perfection of these actions, and from their being performed independently of instruction and experience. A young bee (I must once more repeat) betakes itself to the complex operation of building cells, with as much skill as the oldest of its compatriots. We cannot suppose that it has anyknowledgeof the purposes for which the cells are destined; or of the effects that will result from its feeding the young larvæ, and the like. And if an individual bee be thus destitute of the very materials of reasoning as to its main operations, so must the society in general.
Nor in those remarkable deviations and accommodations to circumstances, instanced under a former head, can we, for considerations there assigned, suppose insects to be influenced by reason. These deviations are still limited in number, and involve acts far too complex and recondite to spring from any process of ratiocinationin an animal whose term of life does not exceed two years.
It does not follow, however, that reason may not have a part in inducing some of these last-mentioned actions, though the actions themselves are purely instinctive. I do not pretend to explain in what way or degree they are combined; but certainly some of the facts do not seem to admit of explanation, except on this supposition. Thus, in the instance above cited from Huber, in which the bees bent a comb at right angles in order to avoid a slip of glass, the remarkable variations in the form of the cells can only, as I have there said, be referred to instinct. Yet the original determination to avoid the glass seems, as Huber himself observes, to indicate something more than instinct, since glass is not a substance against which Nature can be supposed to have forewarned bees, there being nothing in hollow trees (their natural abodes) resembling it either in polish or substance: and what was most striking in their operations was, that they did not wait until they had reached the surface of the glass before changing the direction of the comb, but adopted this variation at a considerable distance, as though they foresaw the inconveniences which might result from another mode of construction[804].—However difficult it may be to form a clear conception of this union of instinct and reason in the same operation, or to define precisely the limits of each, instances of thesemixedactions are sufficiently common among animals to leave little doubt of the fact. It is instinct which leads a greyhound to pursue a hare; but it must be reason that directs "anoldgreyhound to trust the more fatiguing part of the chase to the younger,and to place himself so as to meet the hare in her doubles[805]."
As another instance of these mixed actions in which both reason and instinct seem concerned, but the former more decidedly, may be cited the account which Huber gives of the manner in which the bees of some of his neighbours protected themselves against the attacks of the death's-head-moth (Acherontia Atropos), laid before you in a former letter[806], by so closing the entrance of the hive with walls, arcades, casements, and bastions, built of a mixture of wax and propolis, that these insidious marauders could no longer intrude themselves.
We can scarcely attribute these elaborate fortifications to reason simply; for it appears that bees have recourse to a similar defensive expedient when attacked even by other bees; and the means employed seem too subtle and too well adapted to the end to be the result of this faculty in a bee.
But on the other hand, if it be most probable that in this instance instinct was chiefly concerned, if we impartially consider the facts, it seems impossible to deny that reason had some share in the operations. Pure instinct would have taught the bees to fortify themselves on thefirstattack. If the occupants of a hive had been taken unawares by these gigantic aggressors one night, on the second, at least, the entrance should have been barricadoed. But it appears clear from the statement of Huber, that it was not until the hives had been repeatedly attacked and robbed of nearly their whole stock of honey, that the bees betook themselves to the plan so successfully adopted for the security of their remaining treasures;so that reason taught by experience, seems to have called into action their dormant instinct[807].
If it be thus probable that reason has some influence upon the actions of insects, which must be mainly regarded as instinctive, the existence of this faculty is still more evident in numerous traits of their history where instinct is little if at all concerned. An insect is taught by its instincts the most unerring means to the attainment of certain ends; but these ends, as I have already had occasion more than once to remark, are limited in number, and such only as are called for by its wants in a state of nature. We cannot reasonably suppose insects to be gifted with instincts adapted for occasions that are never likely to happen. If therefore we find them, in these extraordinary and improbable emergencies, still availing themselves of the means apparently best calculated for ensuring their object;—and if in addition they seem in some cases to gain knowledge by experience; if they can communicate information to each other; and if they are endowed with memory;—it appears impossible to deny that they are possessed of reason.—I shall now produce facts in proof of each of these positions; not by any means all that might be adduced, but a few of the most striking that occur to me.
First, then, insects often in cases not likely to be provided for by instinct, adopt means evidently designed for effecting their object.
A certain degree of warmth is necessary to hatch a hen's eggs, and we give her little credit for reason in sitting upon them for this purpose. But if any one hadever seen a hen make her nest in a heap of fermenting dung, among the bark of a hot-bed, or in the vicinity of a baker's oven, where, the heat being as well adapted as the stoves of the Egyptians to bring her chickens into life, she left off the habit of her race, and saved herself the trouble of sitting upon them,—we should certainly pronounce her areasoninghen: and if this hen had chanced to be that very one figured and so elaborately described by Professor Fischer, withthe profile of an old woman[808], a Hindoo metaphysician at least could not doubt of her body, however hen-like, being in truth directed in its operations by the soul of some quondam amateur of poultry-breeding. Now societies of ants have more than once exhibited a deviation from their usual instinct, which to me seems quite as extraordinary and as indicative of reason as would be that supposed in a hen. A certain degree of warmth is required for the exclusion and rearing of their eggs, larvæ and pupæ; and in their ordinary abodes, as you have been already told[809], they undergo great daily labour in removing their charge to different parts of the nest, as its temperature is affected by the presence or absence of the sun. But Reaumur, in refuting the common notion of ants being injurious to bees, tells us that societies of the former often saved themselves all this trouble, by establishing their colonies between the exterior wooden shutters and panes of his glass hives, where, owing to the latter substance being a tolerably good conductor of heat, their progeny wasatall times, and without any necessity of changing their situation, in a constant, equable, and sufficient temperature[810]. Bonnet observed the same fact. He found that a society of ants had piled up their young to the height of several inches, between the flannel-lined case of his glass hives and the glass. When disturbed they ran away with them, but always replaced them[811].
I am persuaded that after duly considering these facts, you will agree with me that it is impossible consistently to refer them to instinct, or to account for them without supposing some stray ant, that had insinuated herself into this tropical crevice, first to have been struck with thethoughtof what a prodigious saving of labour and anxiety would occur to her compatriots by establishing their society here;—that she had communicated herideasto them;—and that they had resolved upon an emigration to this new-discovered country—this Madeira of ants—whose genial clime presented advantages which no other situation could offer. Neither instinct, nor any conceivable modification of instinct, could have taught the ants to avail themselves of a good fortune which but for the invention of glass hives would never have offered itself to a generation of these insects since the creation; for there is nothing analogous in nature to the constant and equable warmth of such a situation, the heat of any accidental mass of fermenting materials soon ceasing, and no heat being given out from a society of bees when lodged in a hollow tree, their natural residence. The conclusion, then, seems irresistible, that reason must have been their guide, inducing a departure from their natural instinct as extraordinary as would be that of ahen which should lay her eggs in a hot-bed, and cease to sit upon them.
The adaptation of means to an end not likely to have been provided for by instinct, is equally obvious in the ingenious mode by which a nest of humble-bees propped up their tottering comb, the particulars of which having before mentioned to you[812], I need not here repeat.
There is perhaps no surer criterion of reason than, after having tried one mode of accomplishing a purpose, adopting another more likely to succeed. Insects are able to stand this test. A bee which Huber watched while soldering the angles of a cell with propolis, detached a thread of this material with which she entered the cell. Instinct would have taught her to separate it of the exact length required; but after applying it to the angle of the cell, she found it too long, and cut off a portion so as to fit it to her purpose[813].
This is a very simple instance; but one such fact is as decisive in proof of reason as a thousand more complex, and of such there is no lack. Dr. Darwin (whose authority in the present case depending not on hearsay, but his own observation, may be here taken,) informs us, that walking one day in his garden he perceived a wasp upon the gravel walk with a large fly nearly as big as itself which it had caught. Kneeling down he distinctly saw it cut off the head and abdomen, and then taking up with its feet the trunk or middle portion of the body to which the wings remained attached, fly away. But a breeze of wind acting upon the wings of the fly turned round the wasp with its burthen, and impeded its progress. Upon this it alighted again on thegravel walk, deliberately sawed off first one wing and then the other; and having thus removed the cause of its embarrassment, flew off with its booty[814]. Could any process of ratiocination be more perfect? "Something acts upon the wings of this fly and impedes my flight. If I wish to reach my nest quickly, I must get rid of them—to effect which, the shortest way will be to alight again and cut them off." These reflections, or others of similar import, must be supposed to have passed through the mind of the wasp, or its actions are altogether inexplicable. Instinct might have taught it to cut off the wings ofallflies, previously to flying away with them. But here it first attempted to fly with the wings on,—was impeded by a certain cause,—discovered what this cause was,—and alighted to remove it. The chain of evidence seems perfect in proof that nothing but reason could have been its prompter.
An analogous though less striking fact is mentioned by Reaumur on the authority of M. Cossigny, who witnessed it in the Isle of France where theSphecinaare accustomed to bury the bodies of cockroaches along with their eggs for provision for their young. He sometimes saw an insect of this tribe attempt to drag after it into its hole a dead cockroach, which was too big to be made to enter by all its efforts. After several ineffectual trials the animal came out, cut off its elytra and some of its legs, and thus reduced in compass drew in its prey without difficulty[815].
Under this head I shall mention but one fact more.—A friend of Gleditsch the observer of the singular economy of the burying beetle (Necrophorus Vespillo) relatedin a former letter[816], being desirous of drying a dead toad, fixed it to the top of a piece of wood which he stuck into the ground. But a short time afterwards, he found that a body of these indefatigable little sextons had circumvented him in spite of his precautions. Not being able to reach the toad, they had undermined the base of the stick until it fell, and then buried both stick and toad[817].
In the second place, insects gain knowledge fromexperience, which would be impossible if they were not gifted with some portion of reason. In proof of their thus profiting, I shall select from the numerous facts that might be brought forward, two only, one of which has been already slightly adverted to[818].
M. P. Huber, in his valuable paper in the sixth volume of theLinnean Transactions[819], states that he has seen large humble-bees, when unable from the size of their head and thorax to reach to the bottom of the long tubes of the flowers of beans, go directly to the calyx, pierce it as well as the tube with the exterior horny parts of their proboscis, and then insert their proboscis itself into the orifice and abstract the honey. They thus flew from flower to flower, piercing the tubes from without, and sucking the nectar, while smaller humble-bees or those with a longer proboscis entered in at the top of the corolla. Now from this statement it seems evident, that the larger bees did not pierce the bottoms of the flowers until they had ascertained by trial that they could not reach the nectar from the top; but that having once ascertainedby experience that the flowers of beans are too strait to admit them, they then, without further attempts in the ordinary way, pierced the bottoms ofallthe flowers which they wished to rifle of their sweets.—M. Aubert du Petit-Thouars observed that humble-bees and the carpenter-bee (Xylocopa[820]violacea) gained access in a similar manner to the nectar ofAntirrhinum Linariaandmajus, andMirabilis Jalappa; as do the common bees of the Isle of France to that ofCanna indica[821]; and I have myself more than once noticed holes at the base of the long nectaries ofAquilegia vulgaris, which I attribute to the same agency.
My second fact is supplied by the same ants, whose sagacious choice of the vicinity of Reaumur's glass hives for their colony has been just related to you. He tells us that of these ants, of which there were such swarms on the outside of the hive, not a single one was ever perceived within; and infers that, as they are such lovers of honey, and there was no difficulty in finding crevices to enter in at, they were kept without, solely from fear of the consequences[822]. Whence arose this fear? We have no ground for supposing ants endowed with any instinctive dread of bees; and Reaumur tells us, that when he happened to leave in his garden, hives of which the bees had died, the ants then never failed to enter them and regale themselves with the honey. It seems reasonable, therefore, to attribute it to experience. Some of the ants no doubt had tried to enter the peopled as they did the empty hive, but had been punished for their presumption,and the dear-bought lesson was not lost on the rest of the community.
Insects, in the third place, are able mutually tocommunicateandreceive information, which, in whatever way effected, would be impracticable if they were devoid of reason. Under this head it is only necessary to refer you to the endless facts in proof, furnished by almost every page of my letters on the history of ants and of the hive-bee. I shall therefore but detain you for a moment with an additional anecdote or two, especially with one respecting the former tribe, which is valuable from the celebrity of the relater.
Dr. Franklin was of opinion that ants could communicate their ideas to each other; in proof of which he related to Kalm, the Swedish traveller, the following fact. Having placed a pot containing treacle in a closet infested with ants, these insects found their way into it, and were feasting very heartily when he discovered them. He then shook them out and suspended the pot by a string from the ceiling. By chance one ant remained, which, after eating its fill, with some difficulty found its way up the string, and thence reaching the ceiling, escaped by the wall to its nest. In less than half an hour a great company of ants sallied out of their hole, climbed the ceiling, crept along the string into the pot, and began to eat again. This they continued until the treacle was all consumed, one swarm running up the string while another passed down[823]. It seems indisputable that the one ant had in this instance conveyednews of the booty to his comrades, who would not otherwise have at once directed their steps in a body to the only accessible route.
A German artist, a man of strict veracity, states that in his journey through Italy he was an eye-witness to the following occurrence. He observed a species of Scarabæus (Ateuchis pilularius?) busily engaged in making, for the reception of its egg, a pellet of dung, which when finished it rolled to the summit of a small hillock, and repeatedly suffered to tumble down its side, apparently for the sake of consolidating it by the earth which each time adhered to it. During this process the pellet unluckily fell into an adjoining hole, out of which all the efforts of the beetle to extricate it were in vain. After several ineffectual trials, the insect repaired to an adjoining heap of dung, and soon returned with three of his companions. All four now applied their united strength to the pellet, and at length succeeded in pushing it out; which being done, the three assistant beetles left the spot and returned to their own quarters[824].
Lastly, insects are endowed withmemory, which (at least in connexion with the purposes to which it is subservient) implies some degree of reason also; and their historian may exclaim with the poet who has so well sung the pleasures of this faculty,