274 



MODIFIED CIECUMNUTATION. 



CuAr. Y. 



Big. 123, 



r?o'^' 



B'a/m.lo'H 



6'4Q\t.m.l39t 



•Jfam. 



fraioimJS/^ 



•ffa/mJ2^ 



Sniitliia Pfundii : hypouastic movempnt 

 of the curved summit of astern, whi 1st 

 straightening itself, traceJ from 9 

 A.M. .July 10th to 3 P.M. 13th. Ajie.x 

 9,7 inches from the vertical gla^*^. 

 Diagram reduced to one-fifth of 

 original scale. Plant illnminnted 

 through skylight ; temp. 17J°-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 hede- 

 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- 

 cuspid'ita in straightening 

 themselves under the com- 

 bined action of hyponasty and 

 apogeotropism moved in a 

 simple straight course, or 

 whether they ciroumnutated, 

 glass filaments were fixed to 

 the crowns of four hooked 

 tips standing in their natural 

 position ; and the movements 

 of the filaments were traced 

 on a vertical glass. AU four 

 tracings resembled each other 

 in a general manner ; but we 

 will give only one (see Pig. 

 I'i2, p. 273). Tha 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 in..50 A.M. on the fol- 

 lowing morning (14th) the 

 hook continued to straighten 

 it?elf, and then zigzagged a 

 short distance to the right. 

 But from 1 p.m. to 10.40 p.m. 

 on the 14th the iiiovemenl 



