{92}
[Illustration]

Again, we have the very curious horned flies,[73] which agree indeed in a
common peculiarity, but in one singularly different in detail, in different
species and not known to have any protecting effect.

Amongst plants, also, we meet with the same peculiarity. The great group of
Orchids presents a number of species which offer strange and bizarre {93}
approximations to different animal forms, and which have often the
appearance of cases of mimicry, as it were in an incipient stage.

[Illustration: HORNED FLIES.]

[Illustration: THE MAGNIFICENT BIRD OF PARADISE.]

The number of similar instances which could be brought forward from amongst
animals and plants is very great, but the examples given are, it is {94}
hoped, amply sufficient to point towards the conclusion which other facts
will, it is thought, establish, viz. that there are causes operating (in
the evocation of these harmonious diverging resemblances) other than
"Natural Selection," or heredity, and other even than merely geographical,
climatal, or any simply external conditions.

Many cases have been adduced of striking likenesses between different
animals, not due to inheritance; but this should be the less surprising, in
that the very same individual presents us with likenesses between different
parts of its body (_e.g._, between the several joints of the backbone),
which are certainly not so explicable. This, however, leads to a rather
large subject, which will be spoken of in the eighth chapter of the present
work. Here it will be enough to affirm (leaving the proof of the assertion
till later) that parts are often homologous which have no direct genetic
relationship,--a fact which harmonizes well with the other facts here
given, but which "Natural Selection," pure and simple, seems unable to
explain.

But surely the independent appearance of similar organic forms is what we
might expect, _a priori_, from the independent appearance of similar
inorganic ones. As Mr. G. H. Lewes well observes,[74] "We do not suppose
the carbonates and phosphates found in various parts of the globe--we do
not suppose that the families of alkaloids and salts have any nearer
kinship than that which consists in the similarity of their elements, and
the conditions of their combination. Hence, in organisms, as in salts,
morphological identity may be due to a community of causal connexion,
ra