Chap. IV. 



CIBCUMNUTATION OF STEMS. 



207 



extreme amount of movement during the time was very small, 

 probably rather less than the Jgth of an inch. 



Fig. 77. 



s^yci'o 



■^SO'p.m. 



A 



?•«.//). S5lr' 



Oersus speciocissimus : circum nutation of stem, illuminated from above, 

 tracea on a liorizontal glass, in A from 9 A.M. to 4.30 P.M. on Nov. 

 23i-d; and in B from 8.3U A.M. on the 24th to 8 A.M. on the 25th. 

 Movement of the bead in B magnified about 38 times. 



(11.) Efd^ra \elix (Araliaceffi, 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 fi 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 

 slow rate, but there could be no doubt about their circumnxita- 

 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, and 



