be received; or embraced by it,
and combined with it into organization, as not to produce the organs
necessary to life, as the brain, or heart, or stomach, that no mule was
produced. Where all the parts necessary to life in these compound animals
were formed sufficiently perfect, except the parts of generation, those
animals were produced which are now called mules.

The formation of the organs of sexual generation, in contradistinction to
that by lateral buds, in vegetables, and in some animals, as the polypus,
the taenia, and the volvox, seems the chef d'oeuvre, the master-piece of
nature; as appears from many flying insects, as in moths and butterflies,
who seem to undergo a general change of their forms solely for the purpose
of sexual reproduction, and in all other animals this organ is not complete
till the maturity of the creature. Whence it happens that, in the
copulation of animals of different species, the parts necessary to life are
frequently completely formed; but those for the purpose of generation are
defective, as requiring a nicer organization; or more exact coincidence of
the particles of nutriment to the irritabilities or appetencies of the
original living filament. Whereas those mules, where all the parts could be
perfectly formed, may have been produced in early periods of time, and may
have added to the numbers of our various species of animals, as before
observed.

As this production of mules is a constant effect from the conjunction of
different species of animals, those between the horse and the female ass
always resembling the horse more than the ass; and those, on the contrary,
between the male ass and the mare, always resembling the ass more than the
mare; it cannot be ascribed to the imagination of the male animal which
cannot be supposed to operate so uniformly; but to the form of the first
nutritive particles, and to their peculiar stimulus exciting the living
filament to select and combine them with itself. There is a similar
uniformity of effect in respect to the colour of the progeny produced
between a white man, and a black woman, which, if I am well informed, is
always of the mulatto kind, or a mixture of the two; which may perhaps be
imputed to the peculiar form of the particles of nutriment supplied to the
embryon by the mother at the early period of its existence, and their
peculiar stimulus; as this effect, like that of the mule progeny above
treated of, is uniform and consistent