| ↑ 1 blocks not present in 1859 1860 1861 1872; present in 1866 1869 |
| The most remarkable case of analogical resemblance ever recorded, though not dependent on adaptation to similar conditions of life, is that given by Mr. Bates with respect to certain butterflies in the Amazonian region closely mimicking other kinds.
|
|
| → of S. America, where, 1872 |
| where, 1866 1869 |
|
| → the latter so 1872 |
| so 1866 1869 |
|
|
in either case have been adapted for tearing flesh, through the natural selection of successive variations; but if this be admitted in the one case, it is unintelligible to me that it should be denied in the other. I am glad to find that so high an authority as Professor Flower has come to this same conclusion. |
|
| The extraordinary cases given in a former chapter, of widely different fishes possessing electric organs,— of widely different insects possessing luminous organs,— and of orchids and asclepiads having pollen-masses with viscid discs, come under this same head of analogical resemblances. But these cases are so wonderful that they were introduced as difficulties or objections to our theory. In all such cases some fundamental difference in the growth or development of the parts, and generally in their matured structure, can be detected. The end gained is the same, but the means, though appearing superficially to be the same, are essentially different. The principle formerly alluded to under the term of
analogical
variation
has probably in these cases often come into play that is, the members of the same class, although only distantly allied, have inherited so much in common in their constitution, that they are apt to vary under similar exciting causes in a similar manner; and this would obviously aid in the acquirement through natural selection of parts or organs, strikingly like each other, independently of their direct inheritance from a common progenitor. |
|
| As species belonging to distinct classes have often been adapted by successive slight modifications to live under nearly similar circumstances,— to inhabit, for instance, the three elements of land, air, and water,— we can perhaps understand how it is that a numerical parallelism has sometimes been observed between the sub-groups of distinct classes. A naturalist, struck with a parallelism of this nature, by arbitrarily raising or sinking the value of the groups in several classes (and all our experience shows that their valuation is as yet arbitrary), could easily extend the parallelism over a wide range; and thus the septenary, quinary, quaternary and ternary classifications have probably arisen. |
|
| There is another and curious class of cases in which close external resemblance does not depend on adaptation to similar habits of life, but has been gained for the sake of protection. I allude to the wonderful manner in which certain butterflies imitate, as first described by Mr. Bates, other and quite distinct species. ↑
This excellent observer
that in
→of S. America, where,
for instance, an Ithomia abounds in gaudy swarms, another butterfly, namely, a Leptalis,
often
mingled in the same
→the latter so
the Ithomia in every shade and stripe of colour and
|
