THE LIFE OF WATER PLANTS. 803 



surface of the water. There it unfolds itself in the full light, and 

 finally lies flat on the water, protected against the wet by a fine, 

 bright coating of wax. It is wonderful how large masses of 

 organized material a water plant can lay up with the help of 

 these floating leaves. The great Victoria Regia grows to its full 

 size in a single year from a small seed. Nearly its whole mass 

 is prepared during growth in the leaves, which can perform such 

 a work only in the strong light and the warmth of the tropical 

 zone. 



Submerged plants, as we have already said, are less well pro- 

 vided as to the reception of light than those with floating leaves. 

 Hence those are chiefly small forms which we find at the bottom 

 of our waters. Of these the Algcz are the most numerous. There 

 are, indeed, on the whole earth no wet, only moderately light 

 places where AJgce have not established a home. Insensible in a 

 high degree alike to heat and cold, they are capable of growing 

 on the snow of the Alps and on the edges of hot springs. We 

 find them on the stones of rushing mountain torrents, in the 

 plunge of the steepest waterfalls, and in the surf of the seacoast, 

 and again at the bottom of the nearly motionless waters of ditches 

 and ponds. The diversity of their habitats corresponds with the 

 immense multitude of their forms. In the form of microscopic 

 dots they will gradually change all the water of a pond or lake 

 into a disagreeable turbid, green, often rank-smelling fluid ; some- 

 times floating on its surface as green or yellow wads dotted with 

 air bubbles ; sometimes they appear at the bottom of the water as 

 thick, roundish bundles of green, tangled threads ; sometimes as 

 slippery brown coatings. 



The Algce, of the sea, or seaweeds, are strikingly rich in color- 

 ing. Besides green, there are in the sea black, brown, and red 

 forms, the last, under favorable conditions of light, often attain- 

 ing great size. They seem to be adapted by their peculiar color- 

 ing to the tempered blue light of the deeper strata of water. In 

 the great deeps the plant life of the sea is extinguished for want 

 of light. At a hundred metres beneath the surface only a few 

 AlgcB are found. These are plants of the shade, needing little 

 light. Some of them continue to grow without interruption 

 through the three months' polar night of Spitzbergen, and de- 

 velop their invisible flowers and fruits at this season with the 

 temperature of the water below the freezing point. The giants 

 of the Algce seek the enjoyment of uninterrupted sunlight. They 

 grow in the deep waters near the shore, and send up slender 

 stalks which pass at the surface of the water into long, shredded 

 leaf forms. Algce of this kind form, on the Chilian coast, for in- 

 stance, forests in which specimens may be found more than two 

 hundred metres long. 



