wax, they make their combs of such a breadth as to extend to the
sides of the hive, to which they cement them by constructions
approaching more or less to the shape of cells. But when a scarcity
of wax happens before they have been able to give to their combs the
requisite diameter, a large vacant space is left between the edges
of these combs, which are only fixed by their upper part, and the
sides of the hive; and they might be pulled down by the weight of the
honey, did not the bees ensure their stability by introducing large
irregular masses of wax between their edges and the sides of the
hive.--A striking instance of this art of securing their magazines
occurred to Huber. A comb, not having been originally well fastened
to the top of his glass hive, fell down during the winter amongst
the other combs, preserving, however, its parallelism with them. The
bees could not fill up the space between its upper edge and the top
of the hive, because they never construct combs of old wax, and they
had not then an opportunity of procuring new: at a more favourable
season they would not have hesitated to build a new comb upon the
old one; but it being inexpedient at that period to expend their
provision of honey in the elaboration of wax, they provided for the
stability of the fallen comb by another process. They furnished
themselves with wax from the other combs, by gnawing away the rims of
the cells more elongated than the rest, and then betook themselves
in crowds, some upon the edges of the fallen comb, others between
its sides and those of the adjoining combs; and there securely fixed
it, by constructing several _ties_ of different shapes between it
and the glass of the hive; some were pillars, others buttresses, and
others beams artfully disposed and adapted to the localities of the
surfaces joined. Nor did they content themselves with repairing the
accidents which their masonry had experienced; they provided against
those which might happen, and appeared to profit by the warning
given by the fall of one of the combs to consolidate the others and
prevent a second accident of the same nature. These last had not been
displaced, and appeared solidly attached by their base; whence Huber
was not a little surprised to see the bees strengthen their principal
points of connexion by making them much thicker than before with old
wax, and forming numerous ties and braces to unite them more closely
to each other and to the walls of their habitation.--What was still
more extraordinary, all this happened in the middle of January, at a
period when the bees ordinarily cluster at the top of the hive, and
do not engage in labours of this kind[781].
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 procedure _invariably_ took place in _every_ bee-hive at a
_fixed_ period--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 of
propolis, 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 to a 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 to _demolish_ what 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
our _barley-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 ranges of 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 the _bottoms_ of 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 of _three_ equal-sized rhomboidal pieces; and the
base of a cell on one side of the comb is composed of portions of
the bases of _three_ cells on the other; but the bottoms of the
intermediate cells in question (though their orifices are perfectly
hexagonal) are composed of _four_ pieces, of which two are hexagonal
and two rhomboidal; and each, instead of corresponding with three
cells on the opposite side, corresponds with _four_. 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 that the 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 whole comb 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 are _calculated_; 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, if _every_ comb contained a _certain_ number of transition
and of male cells, constantly situated in _one_ and the _same_ part
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 the _sensations_ of 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, they _bent 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 will then 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 the
_convex_ side of the bent part of the comb much _larger_, and those on
the _concave_ side much _smaller_ than 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 of _reason_?
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, are _limited_
in 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 adopt _other_
modes of strengthening their combs? Why not, when wax and propolis
are scarce, employ _mud_, 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 the _mortar_ with
which his careful master plasters the crevices between his habitation
and its stand, might answer the end of 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 but _one_ instance
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 disruption in 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 not _reason_ but _instinct_ that is their guide.
The second head under which I proposed contrasting the instincts of
insects with those of the larger animals, was that of their _number_
in 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 Huber _cirières_ (wax makers); but only
to enumerate those presented by that portion of the workers, termed
by Huber _nourrices_ or _petites 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 term _bees_, 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 which _they_ distinctly 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 previously to 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 inclines to 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].