uce the nails, those of the skin to
produce the hair; in the same manner as afterwards about the age of puberty
the beard and other great changes in the form of the body, and disposition
of the mind, are produced in consequence of the new secretion of semen; for
if the animal is deprived of this secretion those changes do not take
place. These changes I conceive to be formed not by elongation or
distention of primeval stamina, but by apposition of parts; as the mature
crab-fish, when deprived of a limb, in a certain space of time has power to
regenerate it; and the tadpole puts forth its feet long after its exclusion
from the spawn; and the caterpillar in changing into a butterfly acquires a
new form, with new powers, new sensations, and new desires.

The natural history of butterflies, and moths, and beetles, and gnats, is
full of curiosity; some of them pass many months, and others even years, in
their caterpillar or grub state; they then rest many weeks without food,
suspended in the air, buried in the earth, or submersed in water; and
change themselves during this time into an animal apparently of a different
nature; the stomachs of some of them, which before digested vegetable
leaves or roots, now only digest honey; they have acquired wings for the
purpose of seeking this new food, and a long proboscis to collect it from
flowers, and I suppose a sense of smell to detect the secret places in
flowers, where it is formed. The moths, which fly by night, have a much
longer proboscis rolled up under their chins like a watch spring; which
they extend to collect the honey from flowers in their sleeping state; when
they are closed, and the nectaries in consequence more difficult to be
plundered. The beetle kind are furnished with an external covering of a
hard material to their wings, that they may occasionally again make holes
in the earth, in which they passed the former state of their existence.

But what most of all distinguishes these new animals is, that they are new
furnished with the powers of reproduction; and that they now differ from
each other in sex, which does not appear in their caterpillar or grub
state. In some of them the change from a caterpillar into a butterfly or
moth seems to be accomplished for the sole purpose of their propagation;
since they immediately die after this is finished, and take no food in the
interim, as the silk-worm in this climate; though it is possible, it might
take honey as food, i