274 



MODIFIED CIRCUMNUTATION. 



CHAP. V. 



Kg. 123. 



Smithia Pfundii : hypoiiastic movement 

 of thecurved summitof astern, whilst 

 straightening itself, traced from 9 

 A.M. July 10th to 3 P.M. 13th. Apex 

 9 inches from the vertical glass. 

 Diagram reduced to one-fifth of 

 original scale. Plant illuminated 

 through skylight ; temp. 17-19 C. 



together. At the same time 

 the loop became open and 

 was thus reconverted into a 

 hook, and this apparently 

 was effected by the geotropic 

 movement of the apex in 

 opposition to epinasty. In 

 the case of Ampelopsis liede- 

 racea, weight plays, as far as 

 we could judge, a more im- 

 portant part in the hooking 

 of the tip. 



In order to ascertain 

 whether the shoots of A. tri- 

 cuspidata in straightening 

 themselves under the com- 

 bined action of hyponasty and 

 apogeotropism moved in a 

 simple straight course, or 

 whether they circumnutated, 

 glass filaments were fixed to 

 the crowns of four hooked 

 tips stand! i -g in their natural 

 position ; and the movements 

 of the filaments were traced 

 on a vertical glass. All four 

 tracings resembled each other 

 in a general manner ; but we 

 will give only one (see Fig. 

 122, p. 273). Th3 filament 

 rose at first, which shows 

 that the hook was straighten- 

 ing itself; it then zigzagged, 

 moving a little to the left 

 between 9.25 A.M. and 9 P.M. 

 From this latter hour on the 

 13th to 10.50 A.M. on the fol- 

 lowing morning (14th) the 

 hook continued to straighten 

 itself, and then zigzagged a 

 short distance to the right. 

 But from 1 P.M. to 10.40 P.M. 

 on the 14th the movement 



