206 CIECUMNUTATION OF STESIS. Chap. IV. 



aceompanyiDg figure (Fig. 76) gives the necessary particulars, 

 and shows that the stem circumnutated, though rather 

 slowly. 



FVicA^ia (garden var.): circnmuutation of stem, kept in darkness, trace*! OD 

 horizontal glass, from 8.30 A.M. to 7 p.m. March 20th. Movement of 

 bead originally magnified about 40 times, here reduced to half .=cale. 



(10.) Cereus speciocissimus (garden var., sometimes called 

 Phylloeactus multiflorus) (CactesB, Fam. 109). — This plant 

 which was growing vigorously from haviog been removed a 

 few days before from the greenhouse to the hot-house, was 

 observed with especial interest, as it seemed so little probable 

 that the stem would circumnutate. The branches are flat, or 

 flabelliform; but some of them are triangular in section, with 

 the three sides hollowed out. A branch of this latter shape, 

 9 inches in length and li in diameter, was chosen for observa- 

 tion, as less likely to circumnutate than a flabelliform branch. 

 The movement of the bead at the end of the glass filament, 

 affixed to the summit of the branch, was traced (A, Fig. 77) 

 from 9.23 A.M. to 4.30 p.m. on Nov. 23rd, during which time it 

 changed its course greatly six times. On the 24th another 

 tracing was made (see B), and the bead on this day changed its 

 course oftener, making in 8 h. what may be considered as four 

 ellipses, with their longer axes differently directed. The position 

 of the stem and its commencing course on the following 

 morning are likewise shown. There can be no doubt that this 

 branch, though appearing quite rigid, circumnutated; but the 



