her like the cups of a conjurer.

"Fourthly, when we revolve in our minds the great similarity of
structure which obtains in all the warm-blooded animals, as well
quadrupeds, birds, and amphibious animals, as in mankind; from the mouse
and bat to the elephant and whale; one is led to conclude that they have
alike been produced from a similar living filament. In some this
filament in its advance to maturity has acquired hands and fingers with
a fine sense of touch, as in mankind. In others it has acquired claws or
talons, as in tigers and eagles. In others, toes with an intervening web
or membrane, as in seals and geese. In others it has acquired cloven
hoofs, as in cows and swine; and whole hoofs in others, as in the horse:
while in the bird kind this original living filament has put forth wings
instead of arms or legs, and feathers instead of hair. In some it has
protruded horns on the forehead instead of teeth in the fore part of the
upper jaw; in others, tusks instead of horns; and in the others, beaks
instead of either. And all this exactly as is seen daily in the
transmutation of the tadpole, which acquires legs and lungs when he
wants them, and loses his tail when it is no longer of service to him.

"Fifthly, from their first rudiment or primordium to the termination of
their lives, all animals undergo perpetual transformations; _which are
in part produced by their own exertions in consequence of their desires
and aversions, of their pleasures and their pains, or of irritations or
of associations; and many of these acquired forms or propensities are
transmitted to their posterity_.

"As air and water are supplied to animals in sufficient profusion, the
three great objects of desire which have changed the forms of many
animals by their desires to gratify them are those of lust, hunger, and
security. A great want of one part of the animal world has consisted in
the desire of the exclusive possession of the females; and these have
acquired weapons to combat each other for this purpose, as the very
thick, shield-like, horny skin on the shoulder of the boar is a defence
only against animals of his own species who strike obliquely upwards,
nor are his tusks for other purposes except to defend himself, as he is
not naturally a carnivorous animal. So the horns of the stag are sharp
to offend his adversary, but are branched for the purpose of parrying or
receiving the thrust of horns similar to his own, and have therefore