CHAP. IV. 



CIBCUMNUTATION OF STEMS. 



207 



exlreme amount of movement during the time was very small, 

 probably rather less than the ^th of an inch. 



Fig. 77. 



Oerius speciocissimus : circumnutation of stem, illuminated from above, 

 traced on a horizontal glass, in A from 9 A.M. to 4.30 P.M. on Nov. 

 23rd ; and in B from 8.30 A.M. on the 24th to 8 A.M. on the 25th. 

 Movement of the bead in B magnified about 38 times. 



(11.) Hfl^ra 'itlix (Araliacese, Fam. 114). The stem is known 

 to be apheliotropic, and several seedlings growing in a pot in 

 the greenhouse became bent in the middle of the summer at 

 right angles f i om the light. On Sept. 2nd some of these stems 

 were tied up so as to stand vertically, and were placed before 

 a north-east window; but to our surprise they were now 

 decidedly heliotropic, for during 4 days they curved them- 

 selves towards the light, and their course being traced on a 

 horizontal glass, was strongly zigzag. During the 6 succeed- 

 ing days they circumnutated over the same small space at a 

 Blow rate, but there could be no doubt about their circumnuta- 

 tion. The plants were kept exactly in the same place before the 

 window, and after an interval of 15 days the stems were 

 again observed during 2 days and their movements traced, aiid 



