. Plant physiology. Plant physiology. Fig. 142.—Normal flower of Epilobrium angustifolium (at the left), and actimorphio flower (at the right), the latter produced by rotation of the plant about a horizontal axis. (After Vochting.) Fig. 143'.—Tip of cotyledon of Panicum ?nileaceum, showing starch grains lying on the phys- ically lower side of each cell. (After Nemec.) phototropic reactions. For the present it can be said simply that under the influence of gravitation the primary shoot grows upward and the primary root downward. 1 Nemec, B., Die Perception des Schwerkraftrezes bei den Pflapzen.
. Plant physiology. Plant physiology. Fig. 142.—Normal flower of Epilobrium angustifolium (at the left), and actimorphio flower (at the right), the latter produced by rotation of the plant about a horizontal axis. (After Vochting.) Fig. 143'.—Tip of cotyledon of Panicum ?nileaceum, showing starch grains lying on the phys- ically lower side of each cell. (After Nemec.) phototropic reactions. For the present it can be said simply that under the influence of gravitation the primary shoot grows upward and the primary root downward. 1 Nemec, B., Die Perception des Schwerkraftrezes bei den Pflapzen. Ber. Deutsch. Bot. Ges. 20: 339-354. 1902. 2 Czapek, F., Stoffwechselprocesse in der geotropisch gereizten Wurzelspitze und in phototropische sensiblen Organen. Ber. Deutsch. Bot. Ges. 20: 464-470. 1902. Czapek, F., and Rudolf, Bertel, Oxydative Stoffweohselvorgange bei pflanzlichen Reizreaktionen. (I. Abhandlung.) Jahrb. wiss. Bot. 43 : 361-467. 1906. Grafe, V., and Linsbauer, K., Zur Kenntnis der Stoffweohselvorgange bei geotropischer Reizung. Sitzungsber. ( Kl.) K. Akad. Wiss. Wien. 119^: 827-852. i9ro. ' Richter, Oswald, Die horizontale Nutation. Sitzungsber ( Kl.) K. Akad. wiss. Wien 119 : 10S1-1084. 1910. ' To the editor there seems to be no opposition between these two views. The suggestions of Nemec and Haberlandt attempt to explain only how the attraction of gravitation may become converted into a pressure of some cell-components upon others, and it is self-evident that this represents only the first link in the chain of cause and effect that finally terminates in an alteration of growth rate in certain cells of the bending region of the plant. Between the pressure postulated by the physical theory and the bending itself, there must occur, as the author has already suggested, an unknown series of chemical and physical reactions, and Cza- pek's studies seem to deal with some of these.— Please note that these images are extracted from
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