I READ the other day in a local paper that “Mr. Seemann, the naturalist of Kellett's Arctic Expedition,” states that plants undergo sleep movements at regular intervals (presumably once in 24 hours) during the long period when the sun never sets. Has this been authenticated? I thought it was well known that a plant does not undergo periodic variations of the kind if it has never been subjected to the regular succession of light and darkness. Other instances are the daily periodicity of the strength of so-called “root-pressure” and of the rate of growth. But if the above observations are correct, not only have the sleep-movements become independent of the ordinary determining conditions in the individual, but they have become hereditary in the species. If the movements really possess the significance usually assigned to them (of checking excessive radiation) this would seem to negative the prevalent view that the state of panmixia alone suffices for the disappearance or degeneration of a structure or mechanism.