ately at what
distance to stand from her fellow-labourers when several are making
their spheres; but she is already so far enabled to judge of distance,
that she always describes her spheres so as to intersect to a certain
extent; and then she unites the points of intersection by perfectly flat
surfaces. By such modifications of instincts which in themselves are not
very wonderful--hardly more wonderful than those which guide a bird to
make its nest--I believe that the hive-bee has acquired, through natural
selection, her inimitable architectural powers.

But this theory can be tested by experiment. Following the example of
Mr. Tegetmeier, I separated two combs, and put between them a long,
thick, rectangular strip of wax: the bees instantly began to excavate
minute circular pits in it; and as they deepened these little pits, they
made them wider and wider until they were converted into shallow basins,
appearing to the eye perfectly true or parts of a sphere, and of
about the diameter of a cell. It was most interesting to observe that,
wherever several bees had begun to excavate these basins near together,
they had begun their work at such a distance from each other that by
the time the basins had acquired the above stated width (i.e. about the
width of an ordinary cell), and were in depth about one sixth of the
diameter of the sphere of which they formed a part, the rims of the
basins intersected or broke into each other. As soon as this occurred,
the bees ceased to excavate, and began to build up flat walls of wax
on the lines of intersection between the basins, so that each hexagonal
prism was built upon the scalloped edge of a smooth basin, instead of on
the straight edges of a three-sided pyramid as in the case of ordinary
cells.

I then put into the hive, instead of a thick, rectangular piece of wax,
a thin and narrow, knife-edged ridge, coloured with vermilion. The bees
instantly began on both sides to excavate little basins near to each
other, in the same way as before; but the ridge of wax was so thin, that
the bottoms of the basins, if they had been excavated to the same depth
as in the former experiment, would have broken into each other from the
opposite sides. The bees, however, did not suffer this to happen, and
they stopped their excavations in due time; so that the basins, as soon
as they had been a little deepened, came to have flat bases; and these
flat bases, formed by thin little plates of the vermi