Chap. I. I'INUS AND CYCAH. 57 



and by this time the filament was attached some way down the 

 little stem. From some unknown cause, the hypocotyl moved 

 far towards the left, but there could be no doubt (Fig. 43) that 

 it circumnutated. Another hypocotyl was similarly observed, 

 and it likewise moved in a strongly zigzag linfe to the same side. 

 This lateral movement was not caused by the attachment of 

 the glass filaments, nor by the action of light ; for no light was 

 allowed to enttr when each observation was made, except from 

 vertically above. 



The hypocotyl of a seedling was secured to a little stick; it 

 bore nine in appearance distinct cotyledons, arranged in a circle. 

 The movements of two nearly opposite ones were observed. The 

 tip of one was painted white, with a mark placed below, and the 

 figure described (Fig. 44, A) shows that it made an irregular 



Fig. 44. 



Pinus pinaster; circnmnutation of two opposite cotyledons, traced on 

 horizontal glass in darlcness, from 8.45 A M. to 8.35 P.M. Nov. 25th. 

 Movement of tip in A magnified about 22 times, here reduced to one- 

 half of original scale. 



circle in the course of about 8 h. During the night it 

 travelled to a considerable distance in the direction indicated 

 by the broken line. A glass filament was attached longitu- 

 dinally to the other cotyledon, and this nearly completed 

 (Fig. 44, B) an irregular circular figure in about 12 hours. 

 During the night it also moved to a considerable distance, in 

 the direction indicated by the broken line. The cotyledons 

 therefore circumnutate independently of the movement of the 

 hypocotyl. Although they moved much during the night, they 

 did not approach each other so as to stand more vertically than 

 during the day. 



