Note 24 — Chapter VII · MODIFIED CIRCUMNUTATION: NYCTITROPIC OR SLEEP MOVEMENTS OF LEAVES. (continued 2)

Pfeffer denies such inheritance; he attributes (‘Die Period. Bewegungen,’ pp. 30–56) the periodicity when prolonged for a day or two in darkness, to “Nachwirkung,” or the after-effects of light and darkness. But we are unable to follow his train of reasoning. There does not seem to be any more reason for attributing such movements to this cause than, for instance, the inherited habit of winter and summer wheat to grow best at different seasons; for this habit is lost after a few years, like the movements of leaves in darkness after a few days. No doubt some effect must be produced on the seeds by the long-continued cultivation of the parent-plants under different climates, but no one probably would call this the “Nachwirkung” of the climates.