Fig. 115.  Canna Warscewiczii:  circumnutation of leaf, traced (A) from 11.30 A.M.  June 10th to 6.40 A.M. 11th; and (B) from 6.40 A.M. 11th to 8.40 A.M. 12th.  Apex of leaf 9 inches from the vertical glass.

(28.) Iris pseudo-acorus (Irideae, Fam. 10).—­The movements of a young leaf, rising 13 inches above the water in which the plant grew, were traced as shown in the figure (Fig. 116), during 27 h. 30 m.  It manifestly circumnutated, though only to a small extent.  On the second morning, between 6.40 A.M. and 2 P.M. (at which latter hour the figure here given ends), the apex changed its course five times.  During the next 8 h. 40 m. it zigzagged much, and descended as far as the lowest dot in the figure, making in its course two very small ellipses; but if these lines had been added to the diagram it would have been too complex.

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. 15o — 16o 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 [page 254] 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 5 ½ 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 2 ½ days.  During the first day (22nd) the tip travelled laterally far to the left, perhaps in consequence of the plant having been

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.

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.

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