GEOGRAPHICAL DISTRIBUTION OF PLANTS. 54? 



the European mountains. On the other hand, the bottom of the sea is clothed with an 



The Ortler Spitz. 



endless variety of green, red, and purple alga? ; and, in the dark caverns of the ocean, 

 the vine-leaved fucus produces its enormous fronds, with a hue as green as that of grass. 

 Melville Island, with its long dreary night, and nine or ten months of rigid winter, has 

 in various places an abundance of moss, lichen, grass, saxifrage, the dwarf-willow, poppy, 

 and sorrel ; and Captain Parry found a ranunculus in full flower, in a sheltered spot, 

 during the second week of June. In a diametrically opposite condition, some plants of 

 the conferva? tribe thrive, living in hot springs, where the temperature is that of boiling 

 water ; and, at the commencement of the seventeenth century, a shrubbery flourished in 

 the crater of the Vesuvian furnace. The rich black loam of the plains sustains luxu- 

 riantly an appropriate vegetation ; while creeping plants derive sustenance from the 

 hardest rocks, and alternate beautifully with the naked projections of mountain masses. 

 Within the tropics magnificent trees grow up under the direct action of the solar beams ; 

 and in dens and caves of the earth, which have never been visited with the light of day, 

 vegetable life defies the perpetual darkness. In the great cavern of the Guacharo, to the 

 south-east of Cumana, Humboldt beheld with astonishment the progress of subterranean 

 vegetation, after having passed a considerable distance beyond the point to which the 

 daylight penetrates. The seeds which the birds carry into the cave to feed their young, 

 spring up wherever they fix in the mould that covers the calcareous incrustations ; and 

 blanched stalks were noticed, which had risen to the height of two feet, with some half- 

 formed leaves. During the visit of the traveller, these traces of organisation amid dark- 

 ness forcibly excited the curiosity of the native Indians, who examined them with the aid 

 of their torches in silent meditation and fear, as if the subterraneous vegetables, pale and 

 disfigured, had been phantoms banished from the face of the earth. To Humboldt, the 

 scene recalled one of the happiest periods of his earliest youth a long abode in the 

 mines of Freiburg, where he had found plants growing in the complete darkness, green 

 as well as blanched. The entire failure of moisture seems to be the only insurmountable 

 obstacle to the growth of plants ; for the sandy desert will " rejoice and blossom as the 

 rose" wherever a very scanty supply of humidity gains access to it. De Candolle makes 



N N 2 



