| ↑ 2 blocks not present in 1859 1860; present in 1861 1866 1869 1872 |
| As a blind species of Bathyscia is found in abundance on shady rocks out of the
caves, the loss of vision in the cave-species has
probably had no relation to its dark habitation; and
it is very
natural that an insect already deprived of vision should readily become adapted to dark caverns.
Another blind genus (Anophthalmus) offers this remarkable peculiarity:
the several distinct
species, as Mr. Murray has remarked, inhabit several distinct European caves and likewise those of Kentucky, and the genus is
found nowhere
except in caves;
but
it is possible that the progenitor
or progenitors
of these several species
may formerly
have ranged widely
over both continents, and have since (like the elephant on both continents)
become extinct, excepting in their present secluded habitations.
|
|
| → rain requisite for seeds to germinate, 1859 1860 1861 1866 1869 |
| sleep, 1872 |
|
| → sleep, 1859 1860 1861 1866 1869 |
| rain requisite for seeds to germinate, 1872 |
|
| → species of 1859 1860 1861 1866 1869 |
| distinct species belonging to 1872 |
|
| → and as I believe 1859 1860 1861 1866 |
| if it be true 1869 1872 |
|
| → parent, if this view be correct, 1859 1860 1861 1866 |
| parent-form, 1869 1872 |
|
| → long-continued 1859 1860 1861 1866 |
| a long course of 1869 1872 |
|
|
Professor Dana; and some of the European cave-insects are very closely allied to those of the surrounding country. It would be
difficult to give any rational explanation of the affinities of the blind cave-animals to the other inhabitants of the two continents on the ordinary view of their independent creation. That several of the inhabitants of the caves of the Old and New Worlds should be closely related, we might expect from the well-known relationship of most of their other productions. ↑ Far from feeling
surprise that some of the cave-animals should be very anomalous, as Agassiz has remarked in regard to the blind fish, the Amblyopsis, and as is the case with the blind Proteus with reference to the reptiles of Europe, I am only surprised that more wrecks of ancient life have not been preserved, owing to the less severe competition to which the
of these dark abodes
have been exposed. |
|
|
| Habit is hereditary with plants, as in the period of flowering, in the
of
→rain requisite for seeds to germinate,
in the
of
→sleep,
&c., and this leads me to say a few words on acclimatisation. As it is extremely common for
→species of
the same genus to inhabit
hot and
cold countries,
→and as I believe
that all the species of the same genus
descended from a single
→parent, if this view be correct,
acclimatisation must be readily effected during
→long-continued
descent. It is notorious that each species is adapted to the climate of its own home: species from an arctic or even from a temperate region cannot endure a tropical climate, or conversely. So again, many succulent plants cannot endure a damp climate. But the degree of adaptation of species to the climates under which they live is often overrated.
|
