As most seedling plants before the development of true leaves are of low, sometimes very low stature, the extreme amount of movement from side to side of their circumnutating stems was small; that of the hypocotyl of Githago segetum was about .2 of an inch, and that of Cucurbita ovifera about .28. A very young shoot of Lathyrus nissolia moved about .14, that of an American oak .2, that of the common nut only .04, and a rather tall shoot of the Asparagus .11 of an inch. The extreme amount of movement of the sheath-like cotyledon of Phalaris Canariensis was .3 of an inch; but it did not move very quickly, the tip crossing on one occasion five divisions of the micrometer, that is, 1/100th of an inch, in 22 m. 5 s. A seedling Nolana prostrata travelled the same distance in 10 m. 38 s. Seedling cabbages circumnutate much more quickly, for the tip of a cotyledon crossed 1/100th of an inch on the micrometer in 3 m. 20 s.; and this rapid movement, accompanied by incessant oscillations, was a wonderful spectacle when beheld under the microscope. The absence of light, for at least a day, does not interfere in the least with the circumnutation of the hypocotyls, epicotyls, or young shoots of the various dicotyledonous seedlings observed by us; nor with that of the young shoots of some monocotyledons. The circumnutation was indeed much plainer in darkness than in light, for if the light was at all lateral the stem bent towards it in a more or less zigzag course. Finally, the hypocotyls of many seedlings are drawn during the winter into the ground, or even beneath it so that they disappear. This remarkable process, which apparently serves for their protection, has been fully described by De Vries.[21] He shows that it is effected by the contraction of the parenchyma-cells of the root. But the hypocotyl itself in some cases contracts greatly, and although at first smooth becomes covered with zigzag ridges, as we observed with Githago segetum. How much of the drawing down and burying of the hypocotyl of Opuntia basilaris was due to the contraction of this part and how much to that of the radicle, we did not observe. [21] ‘Bot. Zeitung,’ 1879, p. 649. See also Winkler in ‘Verhandl. des Bot. Vereins der P. Brandenburg,’ Jahrg. xvi. p. 16, as quoted by Haberlandt, ‘Schutzeinrichungen der Keimpflanze,’ 1877, p. 52.