I was led to investigate this subject by Mr. Waterhouse, who has shown
that the form of the cell stands in close relation to the presence of
adjoining cells; and the following view may, perhaps, be considered
only as a modification of his theory. Let us look to the great
principle of gradation, and see whether Nature does not reveal to us
her method of work. At one end of a short series we have humble-bees,
which use their old cocoons to hold honey, sometimes adding to them
short tubes of wax, and likewise making separate and very irregular
rounded cells of wax. At the other end of the series we have the cells
of the hive-bee, placed in a double layer: each cell, as is well known,
is an hexagonal prism, with the basal edges of its six sides bevelled
so as to join on to a pyramid, formed of three rhombs. These rhombs
have certain angles, and the three which form the pyramidal base of a
single cell on one side of the comb, enter into the composition of the
bases of three adjoining cells on the opposite side. In the series
between the extreme perfection of the cells of the hive-bee and the
simplicity of those of the humble-bee, we have the cells of the Mexican
Melipona domestica, carefully described and figured by Pierre Huber.
The Melipona itself is intermediate in structure between the hive and
humble bee, but more nearly related to the latter: it forms a nearly
regular waxen comb of cylindrical cells, in which the young are
hatched, and, in addition, some large cells of wax for holding honey.
These latter cells are nearly spherical and of nearly equal sizes, and
are aggregated into an irregular mass. But the important point to
notice, is that these cells are always made at that degree of nearness
to each other, that they would have intersected or broken into each
other, if the spheres had been completed; but this is never permitted,
the bees building perfectly flat walls of wax between the spheres
which thus tend to intersect. Hence each cell consists of an outer
spherical portion and of two, three, or more perfectly flat surfaces,
according as the cell adjoins two, three or more other cells. When one
cell comes into contact with three other cells, which, from the spheres
being nearly of the same size, is very frequently and necessarily the
case, the three flat surfaces are united into a pyramid; and this
pyramid, as Huber has remarked, is manifestly a gross imitation of the
three-sided pyramidal basis of the cell of the hive-bee. As in the
cells of the hive-bee, so here, the three plane surfaces in any one
cell necessarily enter into the construction of three adjoining cells.
It is obvious that the Melipona saves wax by this manner of building;
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