. Biology and man. Biology; Human beings. FOLIAGE AS A LIGHT BARRIER This maple presents a mosaic of nearly continuous leaf surface exposed to the sun. Inside its canopy of leaves, very little skylight filters through between leaves; and we see that very little leaf surface is shaded from the light by other leaves young plant in a dark closet, we shall find after a few days that the tip has been growing toward faint light coming through the keyhole. What makes leaves face the light? Do they somehow "know" that light is neces- sary for photosynthesis and so turn to it ? Do they like t
. Biology and man. Biology; Human beings. FOLIAGE AS A LIGHT BARRIER This maple presents a mosaic of nearly continuous leaf surface exposed to the sun. Inside its canopy of leaves, very little skylight filters through between leaves; and we see that very little leaf surface is shaded from the light by other leaves young plant in a dark closet, we shall find after a few days that the tip has been growing toward faint light coming through the keyhole. What makes leaves face the light? Do they somehow "know" that light is neces- sary for photosynthesis and so turn to it ? Do they like the light ? Water Changes Since roots absorb water (and mineral substances) from the soil, the work they can do will depend upon moisture conditions. Now we know that if there is relatively little water in the soil, roots will go down deeper, into the moister layers of earth. From experiments we can see that roots will change the direction of their growth according to the side on which there is the greater humidity. Up and Down No matter which way seeds fall upon the ground, if they sprout at all the stem grows upward and the root downward. If an ordinary plant is placed in a horizontal position, the tip of the stem will bend upward, and the root will bend downward. What makes the root grow downward and the stem grow upward? These questions have been fairly well answered by experiments conducted on many plants, in various countries, over a long time. 254. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Gruenberg, Benjamin C. (Benjamin Charles), 1875-1965; Bingham, N. Eldred (Nelson Eldred), 1901-. Boston, New York, [etc. ] Ginn and company
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Keywords: ., book, bookcentury1900, booksubjectbiology, booksubjecthumanbeings
