Trifolium subterraneum.—A filament was fixed vertically to the uppermost part of the peduncle of a young and upright flower-head (the stem of the plant having been secured to a stick); and its movements were traced during 36 h. Within this time it described (see Fig. 92) a figure which represents four ellipses; but during the latter part of the time the peduncle began to bend downwards, and after 10.30 P.M. on the 24th it curved so rapidly down, that by 6.45 A.M. on the 25th it stood only 19° above the horizon. It went on circumnutating in nearly the same position for two days. Even after the flower-heads have buried themselves in the ground they continue, as will hereafter be shown, to circumnutate. It will also be seen in the next chapter that the sub-peduncles of the separate flowers of _Trifolium repens_ circumnutate in a complicated course during several days. I may add that the gynophore of _Arachis hypogoea_, which looks exactly like a peduncle, circumnutates whilst growing vertically downwards, in order to bury the young pod in the ground. Fig. 92. Trifolium subterraneum: main flower-peduncle, illuminated from above, circumnutation traced on horizontal glass, from 8.40 A.M. July 23rd to 10.30 P.M. 24th. The movements of the flowers of Cyclamen Persicum were not observed; but the peduncle, whilst the pod is forming, increases much in length, and bows itself down by a circumnutating movement. A young peduncle of Maurandia semperflorens, 1½ inch in length, was carefully observed during a whole day, and it made 4½ narrow, vertical, irregular and short ellipses, each at an average rate of about 2 h. 25 m. An adjoining peduncle described during the same time similar, though fewer, ellipses.[4] According to Sachs[5] the flower-stems, whilst growing, of many plants, for instance, those of Brassica napus, revolve or circumnutate; those of Allium porrum bend from side to side, and, if this movement had been traced on a horizontal glass, no doubt ellipses would have been formed. Fritz Müller has described[6] the spontaneous revolving movements of the flower-stems of an Alisma, which he compares with those of a climbing plant. [4] ‘The Movements and Habits of Climbing Plants,’ 2nd edit., 1875, p. 68. [5] ‘Text-Book of Botany,’ 1875, p. 766. Linnæus and Treviranus (according to Pfeffer, ‘Die Periodischen Bewegungen,’ etc., p. 162) state that the flower-stalks of many plants occupy different positions by night and day, and we shall see in the chapter on the Sleep of Plants that this implies circumnutation. [6] ‘Jenaische Zeitsch.,’ B. v. p. 133.