He says, "The subsoil north of latitude 56 degs.
is perpetually frozen, the thaw on the coast not penetrating
above three feet, and at Bear Lake, in latitude 64 degs., not
more than twenty inches. The frozen substratum does not of
itself destroy vegetation, for forests flourish on the surface,
at a distance from the coast."
[10] See Humboldt, Fragments Asiatiques, p. 386: Barton's
Geography of Plants: and Malte Brun. In the latter work it is
said that the limit of the growth of trees in Siberia may be
drawn under the parallel of 70 degs.
[11] Sturt's Travels, vol. ii. p. 74.
[12] A Gaucho assured me that he had once seen a snow-white or
Albino variety, and that it was a most beautiful bird.
[13] Burchell's Travels, vol. i. p. 280.
[14] Azara, vol. iv. p. 173.
[15] Lichtenstein, however, asserts (Travels, vol. ii. p. 25)
that the hens begin sitting when they have laid ten or twelve
eggs; and that they continue laying, I presume, in another
nest. This appears to me very improbable. He asserts that four
or five hens associate for incubation with one cock, who sits
only at night.
[16] When at the Rio Negro, we heard much of the indefatigable
labours of this naturalist. M. Alcide d'Orbigny, during the
years 1825 to 1833, traversed several large portions of South
America, and has made a collection, and is now publishing the
results on a scale of magnificence, which at once places himself
in the list of American travellers second only to Humboldt.