. Elementary plant physiology. Plant physiology. 114 Elementary Plant Physiology. and shoot. What connection is shown with the habit of growth of the plant ? 123. Prophototropism.—Germinate a number of seeds of oats or wheat in a shallow dish of moist soil, and, when the leaves begin to appear, set in a cardboard box. Cut a circu- lar hole in one side of the box, at the level of the seedlings. Roll up a sheet of paper into a tube, and fasten to the box in such manner that light enters through the tube only. Cover the box to exclude light, except through the tube. Note the. Fig. 83.—Phototropic
. Elementary plant physiology. Plant physiology. 114 Elementary Plant Physiology. and shoot. What connection is shown with the habit of growth of the plant ? 123. Prophototropism.—Germinate a number of seeds of oats or wheat in a shallow dish of moist soil, and, when the leaves begin to appear, set in a cardboard box. Cut a circu- lar hole in one side of the box, at the level of the seedlings. Roll up a sheet of paper into a tube, and fasten to the box in such manner that light enters through the tube only. Cover the box to exclude light, except through the tube. Note the. Fig. 83.—Phototropic chamber. /, tube through which light enters. Schleichert. After position of the leaves a day or two later. In this instance the leaves are placed with their apices directed toward the source of the rays of light, with their axes parallel to the rays. 124. Diaphototropism.—Place in a pot a Malva, Heli- anthus, or Geranium grown in the open air, and place near a window with a southern exposure. Note the position assumed by the younger leaves a few days later. How does this reac- tion compare with that shown by leaves of grasses? The same form of reaction may be seen if a leafy shoot of sunflower is bent down to a horizontal position and fastened. Note the position of the leaf blades before and two days after the 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 MacDougal, Daniel Trembly, 1865-1958. New York, London [etc. ] Longmans, Green, and Co.
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