alloped 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, square 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
{229} 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 bottoms; and these flat bottoms,
formed by thin little plates of the vermilion wax having been left
ungnawed, were situated, as far as the eye could judge, exactly along the
planes of imaginary intersection between the basins on the opposite sides
of the ridge of wax. In parts, only little bits, in other parts, large
portions of a rhombic plate had been left between the opposed basins, but
the work, from the unnatural state of things, had not been neatly
performed. The bees must have worked at very nearly the same rate on the
opposite sides of the ridge of vermilion wax, as they circularly gnawed
away and deepened the basins on both sides, in order to have succeeded in
thus leaving flat plates between the basins, by stopping work along the
intermediate planes or planes of intersection.

Considering how flexible thin wax is, I do not see that there is any
difficulty in the bees, whilst at work on the two sides of a strip of wax,
perceiving when they have gnawed the wax away to the proper thinness, and
then stopping their work. In ordinary combs it has appeared to me that the
bees do not always succeed in working at exactly the same rate from the
opposite sides; for I have noticed half-completed rhombs at the base of a
just-commenced cell, which were slightly concave on one side, where I
suppose that the bees had excavated too quickly, and convex on the opposed
side, where the bees had worked less quickly. In one well-marked instance,
I put the comb back into the hive, and allowed the bees to go on working
for a short time, and again examined the cell, and I found that the rhombic
{230} plate had been completed, and had become _perfectly flat_: it was
absolutely impossible, from the e