Origin of Species Variorum

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. As a blind species of Bathyscia is found in abundance on shady rocks far from caves, the loss of vision in the cave-species of this one genus 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, whilst furnished with eyes, formerly may have ranged widely over both continents, and since (like the elephant on both continents) have become extinct, excepting in their present secluded abodes. 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 inhabitants of these dark abodes must have been exposed.

Acclimatisation .

Habit is hereditary with plants, as in the period of flowering, in the amount of rain requisite for seeds to germinate, in the time 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