Page:The Works of Aristotle - Vol. 6 - Opuscula (1913).djvu/109

Rh the saltness gains the upper hand, as we have already shown, and rarities resembling one another are left between the particles of sand; the sun has therefore no power to produce or perpetuate any continuous plant life; and so in deserts separate species of plants will not occur, but species similar to one another.

which grow on the surface of the water will only do so when there is density in the water; the reason of this is that, when heat touches water which has no current to move it, something of the nature of a cloud comes over it and retains a little of the air, and the moisture putrefies and the heat draws it up, and it spreads over the face of the water. Such a plant has no root, because roots will only attach themselves to the hard particles of the earth, and the particles of water are loose and scattered. The heat then comes forth with the putrefaction which takes place on the surface of the water. Such a plant has no leaves because it is produced under conditions which are far from temperate, and its parts are not compact, because the parts of water are not compact. It is for this reason too that such plants grow like threads. It is because the parts of earth are compact that the plants too which grow in the earth are compact. Sometimes putrefactions are set up in damp, smoky ground, and hold the air—the sun causing them to appear when rain and winds are frequent—and the dryness of the earth will make their roots dry up and solidify, and thus fungi and mushrooms and the like will be produced. In places that are exceedingly warm, because the heat assimilates the water in the interior of the earth and the sun holds the heat, a vapour is formed and a plant is thus produced. This process takes place in all warm places, and the formation of the plant is thus completed. A cold locality causes a similar but contrary process; the cold air forces the heat downwards and its particles collect together, and the ground undergoes concoction with the moisture present in it; the ground is then cleft open and a plant emerges from it. Where the