ions long before the existence of animals; and many
families of these animals long before other families of them, shall we
conjecture that one and the same kind of living filaments is and has been
the cause of all organic life?

This idea of the gradual formation and improvement of the animal world
accords with the observations of some modern philosophers, who have
supposed that the continent of America has been raised out of the ocean at
a later period of time than the other three quarters of the globe, which
they deduce from the greater comparative heights of its mountains, and the
consequent greater coldness of its respective climates, and from the less
size and strength of its animals, as the tygers and allegators compared
with those of Asia or Africa. And lastly, from the less progress in the
improvements of the mind of its inhabitants in respect to voluntary
exertions.

This idea of the gradual formation and improvement of the animal world
seems not to have been unknown to the ancient philosophers. Plato having
probably observed the reciprocal generation of inferior animals, as snails
and worms, was of opinion, that mankind with all other animals were
originally hermaphrodites during the infancy of the world, and were in
process of time separated into male and female. The breasts and teats of
all male quadrupeds, to which no use can be now assigned, adds perhaps some
shadow of probability to this opinion. Linnaeus excepts the horse from the
male quadrupeds, who have teats; which might have shewn the earlier origin
of his exigence; but Mr. J. Hunter asserts, that he has discovered the
vestiges of them on his sheath, and has at the same time enriched natural
history with a very curious fact concerning the male pigeon; at the time of
hatching the eggs both the male and female pigeon undergo a great change in
their crops; which thicken and become corrugated, and secrete a kind of
milky fluid, which coagulates, and with which alone they for a few days
feed their young, and afterwards feed them with this coagulated fluid mixed
with other food. How this resembles the breasts of female quadrupeds after
the production of their young! and how extraordinary, that the male should
at this time give milk as well as the female! See Botanic Garden, Part II.
Note on Curcuma.

The late Mr. David Hume, in his posthumous works, places the powers of
generation much above those of our boasted reason; and adds, that reason
can only ma