ere is often made use of for the
scattering of seeds, by their being furnished with special structures of
very different kinds. The diverse modes by which such seeds are dispersed
are well expressed by Mr. Darwin. He says:[50] "Seeds are disseminated {66}
by their minuteness,--by their capsule being converted into a light
balloon-like envelope,--by being embedded in pulp or flesh, formed of the
most diverse parts, and rendered nutritious, as well as conspicuously
coloured, so as to attract and be devoured by birds,--by having hooks and
grapnels of many kinds and serrated awns, so as to adhere to the fur of
quadrupeds,--and by being furnished with wings and plumes, as different in
shape as elegant in structure, so as to be wafted by every breeze."

[Illustration: SKELETON OF THE FLYING-DRAGON.
(Showing the elongated ribs which support the flitting organ.)]

Again, if we consider the poisoning apparatus possessed by different
animals, we find in serpents a perforated--or rather very deeply
channelled--tooth. In wasps and bees the sting is formed of modified parts,
accessory in reproduction. In the scorpion, we have the median terminal
process of the body specially organized. In the spider, we have a specially
constructed antenna; and finally in the centipede a pair of modified
thoracic limbs.

[Illustration: A CENTIPEDE.]

It would be easy to produce a multitude of such instances of similar ends
being attained by dissimilar means, and it is here contended that by "the
action of Natural Selection" _only_ it is so improbable as to be
practically impossible for two exactly similar structures to have ever been
independently developed. It is so because the number of possible {67}
variations is indefinitely great, and it is therefore an indefinitely great
number to one against a similar series of variations occurring and being
similarly preserved in any two independent instances.

The difficulty here asserted applies, however, only to pure Darwinism,
which makes use _only_ of indirect modifications through the survival of
the fittest.

Other theories (for example, that of Mr. Herbert Spencer) admit the
_direct_ action of conditions upon animals and plants--in ways not yet
fully understood--there being conceived to be at the same time a certain
peculiar but limited power of response and adaptation in each animal and
plant so acted on. Such theories have not to contend against the difficulty
proposed, and it is here u