lived throughout the winter, and consequently required a store of
honey: there can in this case be no doubt that it would be an advantage
to our humble-bee, if a slight modification of her instinct led her to
make her waxen cells near together, so as to intersect a little; for a
wall in common even to two adjoining cells, would save some little wax.
Hence it would continually be more and more advantageous to our
humble-bee, if she were to make her cells more and more regular, nearer
together, and aggregated into a mass, like the cells of the Melipona;
for in this case a large part of the bounding surface of each cell
would serve to bound other cells, and much wax would be saved. Again,
from the same cause, it would be advantageous to the Melipona, if she
were to make her cells closer together, and more regular in every way
than at present; for then, as we have seen, the spherical surfaces
would wholly disappear, and would all be replaced by plane surfaces;
and the Melipona
would make a comb as perfect as that of the hive-bee. Beyond this stage
of perfection in architecture, natural selection could not lead; for
the comb of the hive-bee, as far as we can see, is absolutely perfect
in economising wax.
Thus, as I believe, the most wonderful of all known instincts, that of
the hive-bee, can be explained by natural selection having taken
advantage of numerous, successive, slight modifications of simpler
instincts; natural selection having by slow degrees, more and more
perfectly, led the bees to sweep equal spheres at a given distance from
each other in a double layer, and to build up and excavate the wax
along the planes of intersection. The bees, of course, no more knowing
that they swept their spheres at one particular distance from each
other, than they know what are the several angles of the hexagonal
prisms and of the basal rhombic plates. The motive power of the process
of natural selection having been economy of wax; that individual swarm
which wasted least honey in the secretion of wax, having succeeded
best, and having transmitted by inheritance its newly acquired
economical instinct to new swarms, which in their turn will have had
the best chance of succeeding in the struggle for existence.
No doubt many instincts of very difficult explanation could be opposed
to the theory of natural selection, cases, in which we cannot see how
an instinct could possibly have originated; cases, in which no
intermediate gradations are known to exist; cases of instinct of
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