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 an inverted
pyramid, 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 flat surfaces,
according as the cell adjoins two, three or more other cells. When one
cell rests on 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
base 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, and what is more importan