If there were a series of created types, there may naturally have been
what I may call sub-types; which would be certain well-marked stages on
the way to the final form. Such sub-type forms would naturally occur at
different ages, and being marked would show their place in the scale,
and their connection with the ultimate perfect form. Such a possibility
would exactly account for the series of _Eohippus, Hipparion_, and
horse, which we have already instanced; and still more so for the rise
and disappearance of the great Mesozoic Saurians when their object was
fulfilled. Deny guidance and type, and everything becomes confused. Why
should variation take certain directions? how comes it that natural
forces and conditions of life so occur and co-operate as to produce the
variety of changes needed?
And there is also one other general objection which I desire to state.
Why should _development_ have gone in different directions _towards the
same object_? I grant that different circumstances would produce
different changes, but not for the same purpose. For example take
eye-sight. The world shows several types of eye. The _insect_ eye quite
unlike any other; the crustacean eye also distinct; and birds, fishes,
and animals having an eye which is generally similar and is somewhat
imitated by the eye of the _cuttle fish_ (which is not a _fish_, but a
_cephalopod_).
Pages:
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86