the hardihood to assert
that in the case of the skeleton the Deity has endeavoured to show his
_ingenuity_, by the manifold functions to which he has made the same
structure subservient; while in the case of the eye he has endeavoured
to show his _resources_, by the manifold structures which he has adapted
to serve the same function? If so, it becomes a most unfortunate
circumstance that, throughout both the vegetable and animal kingdoms,
all cases which can be pointed to as showing ingenious adaptation of the
same typical structure to the performance of widely different
functions--or cases of homology without analogy,--are cases which come
within the limits of the same natural group of plants and animals, and
therefore admit of being equally well explained by descent from a common
ancestry; while all cases of widely different structures performing the
same function--or cases of analogy without homology,--are to be found in
different groups of plants or animals, and are therefore suggestive of
independent variations arising in the different lines of hereditary
descent.

To take a specific illustration. The octopus, or devil-fish, belongs to
a widely different class of animals from a true fish; and yet its eye,
in general appearance, looks wonderfully like the eye of a true fish.
Now, Mr. Mivart pointed to this fact as a great difficulty in the way of
the theory of evolution by natural selection, because it must clearly be
a most improbable thing that so complicated a structure as the eye of a
fish should happen to be arrived at through each of two totally
different lines of descent. And this difficulty would, indeed, be a
formidable one to the theory of evolution, if the similarity were not
only analogical but homological. Unfortunately for the objection,
however, Darwin clearly showed in his reply that in no one anatomical or
homologous feature do the two structures resemble one another; so that,
in point of fact, the two organs do not resemble one another in any
particular further than it is necessary that they should, if both are to
be analogous, or to serve the same function as organs of sight. But now,
suppose that this had not been the case, and that the two structures,
besides presenting the necessary superficial or analogical resemblance,
had also presented an anatomical or homologous resemblance, with what
force might it have then been urged,--Your hypothesis of hereditary
descent with progressive modification