nd lead out a swarm; there is no increased heat, consequently
nothing that renders the hive insupportable to her.

This conjecture, which affords a tolerable explanation why bees persist
in remaining in the hive, though the mutilated queen has left it, is no
reason for the motive inducing the queen herself to depart. Her instinct
is altered; that is the whole that I can perceive. I can discern nothing
more. It is very fortunate for the hive, that this queen departs, for
the bees incessantly attend her; nor do they ever think of procuring
another while she remains; and if she was long of leaving them, it would
be impossible to replace her; for the workers worms would exceed the
term at which they are convertible into royal worms, and the hive would
perish. Observe, that the eggs dropped by the mutilated queen can never
serve for replacing her, for, not being deposited in cells, they dry and
produce nothing.

I have yet to say a few words on females laying male eggs only. M.
Schirach supposes that one branch of their double ovary suffers some
alteration. He seems to think that one of these branches contains the
eggs of males, while the other has none but common eggs, and as he
ascribes the inability of certain queens to lay the latter to some
disease, his conjecture becomes very plausible. In fact, if the eggs of
males and workers are indiscriminately mixed in both branches of the
ovary, it appears at first sight that whatever cause acts on that organ,
it should equally affect both species of eggs. If on the contrary, one
branch is occupied by the eggs of drones only, and the other contains
none but common eggs, we may conceive how disease affects the one, while
the other remains untouched. Though this conjecture is probable, it is
confuted by observation. We lately dissected queens, which laid none but
male eggs, and found both branches of the ovary equally well expanded,
and equally sound, if I may use the expression. The only difference
that struck us was that in these two branches, the eggs were apparently
not so close together as in the ovaries of queens laying both kinds of
eggs.

_PREGNY, 12. September 1791._

LETTER XIII.

_ECONOMICAL CONSIDERATIONS ON BEES._

In this letter I shall treat of the advantages that may be derived from
the new invented hives, called _book_ or _leaf_ hives, in promoting the
_economical knowledge_ of bees.

It is needless to relate the different methods hitherto employe