Origin of Species Variorum

→ may be attributed 1872

wholly 1859 1860 1861 1866 1869

→ cave rat (Neotoma), two of which were captured by 1872

cave-rat, the eyes are of immense size; and 1859 1860

cave-rat (Neotoma), two of which were captured by 1861 1866 1869

→ at above half a mile distance from the mouth of the cave, and therefore not 1861 1866 1869 1872

thought that it regained, after living some days 1859 1860

→ profoundest depths, the eyes were lustrous and of large size; and these animals, as I am informed by Professor Silliman, after having been exposed for about a month to a graduated light, acquired a dim perception of objects. 1869 1872

light, some slight power of vision. 1859 1860

profoundest depths, the eyes were lustrous and of large size; but these animals, as I am informed by Professor Silliman, having been exposed for about a month to a graduated light, acquired a dim perception of objects when brought towards their eyes, and blinked. 1861 1866

↑ 1 blocks not present in 1861 1866 1869 1872; present in 1859 1860

In the same manner as in Madeira the wings of some of the insects have been enlarged, and the wings of others have been reduced by natural selection aided by use and disuse, so in the case of the cave-rat natural selection seems to have struggled with the loss of light and to have increased the size of the eyes; whereas with all the other inhabitants of the caves, disuse by itself seems to have done its work.

→ in accordance with the old 1872

on the common 1859 1860 1861 1866 1869

→ OMIT 1869 1872

but, as Schiödte and others have remarked, 1859 1860

OMIT 1861 1866

→ OMIT 1869 1872

and the cave-insects of 1859 1860

if we look at 1861 1866

→ OMIT 1869 1872

continents are not more closely allied than might have been anticipated from the general resemblance of the other inhabitants of North America and Europe. 1859 1860

whole faunas; and with respect to the insects alone, Schiödte has remarked, " 1861 1866

swimmers if they had not been able to swim at all and had stuck to the wreck.

The eyes of moles and of some burrowing rodents are rudimentary in size, and in some cases are quite covered

....

by skin and fur. This state of the eyes is probably due to gradual reduction from disuse, but aided perhaps by natural selection. In South America, a burrowing rodent, the tuco-tuco, or Ctenomys, is even more subterranean in its habits than the mole; and I was assured by a Spaniard, who had often caught them, that they were frequently

blind;

blind.

one

One

which

kept alive was certainly in this condition, the cause, as appeared on dissection, having been inflammation of the nictitating membrane. As frequent inflammation of the eyes must be injurious to any animal, and as eyes are certainly not

indispensable

necessary

to animals

with

having

subterranean habits, a reduction in their

size

size,

with the adhesion of the eyelids and growth of fur over them, might in such case be an advantage; and if so, natural selection would

constantly

....

aid the effects of disuse.

It is well known that several animals, belonging to the most different classes, which inhabit the caves of

Styria

Carniola

and of Kentucky, are blind. In some of the crabs the foot-stalk for the eye remains, though the eye is

gone;

gone;—

the stand for the telescope is there, though the telescope with its glasses has been lost. As it is difficult to imagine that eyes, though useless, could be in any way injurious to animals living in darkness,

I attribute

....

their loss →may be attributed to disuse. In one of the blind animals, namely, the →cave rat (Neotoma), two of which were captured by Professor Silliman →at above half a mile distance from the mouth of the cave, and therefore not in the →profoundest depths, the eyes were lustrous and of large size; and these animals, as I am informed by Professor Silliman, after having been exposed for about a month to a graduated light, acquired a dim perception of objects. ↑

It is difficult to imagine conditions of life more similar than deep limestone caverns under a nearly similar climate; so

that

that,

→in accordance with the old view of the blind animals having been separately created for the American and European caverns,

very close

similarity in their organisation and affinities might have been

expected;

expected.

→OMIT

this

This

....

not

certainly not

....

the

....

case,

case

....

→OMIT

the

....

two

....

→OMIT This is certainly not the case if we look at the two whole faunas; and with respect to the insects alone, Schiödte has remarked,

"We

are accordingly prevented from considering the entire phenomenon in any other light than something purely local, and the similarity which is exhibited in a few forms between the Mammoth cave (in Kentucky) and the caves in Carniola, otherwise than as a very plain expression of that analogy which subsists