PHYSIOGNOMY OF PLANTS. 229 



atories of Nature, in the clouds and in the pulsating vessels of ani- 

 mals and plants. Organic forms also descend deep below the surface 

 of the earth, wherever rain or surface water can percolate either by 

 natural cavities or by mines or other excavations made by man : the 

 subterranean cryptogamic Flora was an object of my scientific re- 

 search in the early part of my life. Thermal springs of very high 

 temperature nourish small Hydropores, Conferva, and Oscillatoria. 

 At Bear Lake, near the Arctic Circle, Richardson saw the ground, 

 which continues frozen throughout the summer at a depth of twenty 

 inches, covered with flowering plants. 



We do not yet know where life is most abundant whether on 

 continents or in the unfathomed depths of the ocean. Through the 

 excellent work of Ehrenberg, " Uber das Verhalten des kleinsten 

 Lebens," we have seen the sphere of organic life extend, and its 

 horizon widen before our eyes, both in the tropical parts of the 

 ocean and in the fixed or floating masses of ice of the Antarctic seas. 

 Silicious-shelled Polygastrica, and even Coscinodiscae, with their 

 green ovaries, have been found alive enveloped in masses of ice only 

 twelve degrees from the pole; the small black Glacier flea (Desoria 

 glacialis) and Podurellge inhabit the narrow tubular holes examined 

 by Agassiz in the Swiss glaciers. Ehrenberg has shown that on 

 several microscopic Infusoria (Synedra, Cocconeis) others live as 

 parasites, and that in the Gallionellae such is their prodigious power 

 of development, or capability of* division, that in the space of four 

 days an animalcule invisible to the naked eye can form two cubic 

 feet of the Bilin polishing slate. In the sea, gelatinous worms, 

 living or dead, shine like stars, ( 5 ) and by their phosphoric- light 

 change the surface of the wide ocean into a sea of fire. Ineffaceable 

 is the impression made on my mind by the calm nights of the torrid 

 zone, on the waters of the Pacific. I still see the dark azure of the 

 firmament, the constellation of the Ship near the zenith, and that of 

 the Cross declining towards the horizon, shedding through the per- 

 fumed air their soft and planetary lustre; while bright furrows of 

 flashing light marked the track of the dolphins through the midst 

 of the foaming waves. 



Not only the ocean, but also the waters of our marshes, hide from 

 us an innumerable multitude of strange forms. The naked eye can 

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