Fig. 116. Iris pseudo-acorus: circumnutation of leaf, traced from 10.30 A.M. May 28th to 2 P.M. 29th. Tracing continued to 11 P.M., but not here copied. Apex of leaf 12 inches beneath the horizontal glass, so figure considerably magnified. Temp. 15°–16° C. (29.) Crinum Capense (Amaryllideae, Fam. 11).—The leaves of this plant are remarkable for their great length and narrowness: one was measured and found to be 53 inches long and only 1.4 broad at the base. Whilst quite young they stand up almost vertically to the height of about a foot; afterwards their tips begin to bend over, and subsequently hang vertically down, and thus continue to grow. A rather young leaf was selected, of which the dependent tapering point was as yet only 5½ inches in length, the upright basal part being 20 inches high, though this part would ultimately become shorter by being more bent over. A large bell-glass was placed over the plant, with a black dot on one side; and by bringing the dependent apex of the leaf into a line with this dot, the accompanying figure (Fig. 117) was traced on the other side of the bell, during 2½ days. During the first day (22nd) the tip travelled laterally far to the left, perhaps in consequence of the plant having been disturbed; and the last dot made at 10.30 P.M. on this day is alone here given. As we see in the figure, there can be no doubt that the apex of this leaf circumnutated. Fig. 117. Crinum Capense: circumnutation of dependent tip of young leaf, traced on a bell-glass, from 10.30 P.M. May 22nd to 10.15 A.M. 25th. Figure not greatly magnified. A glass filament with little triangles of paper was at the same time fixed obliquely across the tip of a still younger leaf, which stood vertically up and was as yet straight. Its movements were traced from 3 P.M. May 22nd to 10.15 A.M. 25th. The leaf was growing rapidly, so that the apex ascended greatly during this period; as it zigzagged much it was clearly circumnutating, and it apparently tended to form one ellipse each day. The lines traced during the night were much more vertical than those traced during the day; and this indicates that the tracing would have exhibited a nocturnal rise and a diurnal fall, if the leaf had not grown so quickly. The movement of this same leaf after an interval of six days (May 31st), by which time the tip had curved outwards into a horizontal position, and had thus made the first step towards becoming dependent, was traced orthogonically by the aid of a cube of wood (in the manner before explained); and it was thus ascertained that the actual distance travelled by the apex, and due to circumnutation, was 3 1/8 inches in the course of 20½ h. During the next 24 h. it travelled 2½ inches. The circumnutating movement, therefore, of this young leaf was strongly marked.