here, throughout Patagonia, in Northern Chile, and at the Galapagos
Islands, I met with these birds wherever there were lakes of brine. I
saw them here wading about in search of food--probably for the worms
which burrow in the mud; and these latter probably feed on infusoria or
confervae. Thus we have a little living world within itself adapted to
these inland lakes of brine. A minute crustaceous animal (Cancer
salinus) is said [4] to live in countless numbers in the brine-pans at
Lymington: but only in those in which the fluid has attained, from
evaporation, considerable strength--namely, about a quarter of a pound
of salt to a pint of water. Well may we affirm that every part of the
world is habitable! Whether lakes of brine, or those subterranean ones
hidden beneath volcanic mountains--warm mineral springs--the wide
expanse and depths of the ocean--the upper regions of the atmosphere,
and even the surface of perpetual snow--all support organic beings.
To the northward of the Rio Negro, between it and the inhabited country
near Buenos Ayres, the Spaniards have only one small settlement,
recently established at Bahia Blanca. The distance in a straight line
to Buenos Ayres is very nearly five hundred British miles. The
wandering tribes of horse Indians, which have always occupied the
greater part of this country, having of late much harassed the outlying
estancias, the government at Buenos Ayres equipped some time since an
army under the command of General Rosas for the purpose of
exterminating them. The troops were now encamped on the banks of the
Colorado; a river lying about eighty miles northward of the Rio Negro.
When General Rosas left Buenos Ayres he struck in a direct line across
the unexplored plains: and as the country was thus pretty well cleared
of Indians, he left behind him, at wide intervals, a small party of
soldiers with a troop of horses (a posta), so as to be enabled to keep
up a communication with the capital. As the Beagle intended to call at
Bahia Blanca, I determined to proceed there by land; and ultimately I
extended my plan to travel the whole way by the postas to Buenos Ayres.
August 11th.--Mr. Harris, an Englishman residing at Patagones, a guide,
and five Gauchos who were proceeding to the army on business, were my
companions on the journey. The Colorado, as I have already said, is
nearly eighty miles distant: and as we travelled slowly, we were two
days and a half on the road. The whole line of country deserves
scarcely a better name than that of a desert. Water is found only in
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