Note 8 — Chapter VIII · MODIFIED CIRCUMNUTATION: MOVEMENTS EXCITED BY LIGHT.

According to Frank (‘Die nat. Wagerechte Richtung von Pflanzentheilen,’ 1870, p. 46) the root-leaves of many plants, kept in darkness, rise up and even become vertical; and so it is in some cases with shoots. (See Rauwenhoff, ‘Archives Néerlandaises,’ tom. xii. p. 32.) These movements indicate apogeotropism; but when organs have been long kept in the dark, the amount of water and of mineral matter which they contain is so much altered, and their regular growth is so much disturbed, that it is perhaps rash to infer from their movements what would occur under normal conditions. (See Godlewski, ‘Bot. Zeitung,’ Feb. 14th, 1879.)