254 CIECUMNUTATION OF LEAVES. Chap. IV. 



their tips begin to bend over, and subsequenily hang vertically 

 down, and thus continue to grow. A rather young leaf was 

 selected, of which the dependent tapering point was as yet only 

 55 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 

 2i days. During the first day (22nd) the tip travelled laterally 

 far to the left, perhaps in consequence of the plant having been 



Fig. 117. 

 10°45'p.m.S4^ .^ 



ii''p.m.23'^.^ \^ 



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. 25tli. 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 move- 

 ments 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 circum- 

 nutating, 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. 



