Chap. IV. 



DICOTYLEDONS. 



231 



terminal shoot of a young plant, growing very vigorously, was 

 selected for observation. The young leaves at iirst stand up 

 vertically and close together, but they soon bend outwards and 

 downwards, so as to become horizontal, and often at the same 

 time a little to one side. A filament was fixed to the tip of a 

 young leaf whilst still highly inclined, and the first dot was 

 made on the vertical glass at 8.30 a.m. June 13th, but it curved 

 downwards so quickly that by 6.40 a.m. on the following 

 morning it stood only a little above the horizon. In Fig. 96 



Kig. 98 



a 





W-lS'p.mWb 



5s \e''4o'a.m.U-^ 



t0''4^'p.m.l4^h 



Dianthus cwyophijllus : circumnutatjon of young leaf, traced from 10.15 

 P.M. June 13th to 10..35 P.M. 16th. Apex of leaf stood, at the close of 

 our observations, 8f inches from the vertical glass, so tracing not 

 greatly magnified. The leaf was 5J inches long. Temp. t5J°-17J° C. 



the long, slightly zigzag line representing this rapid downward 

 course, which was somewhat inclined to the left, is not given ; 

 but the figure shows the highly tortuous and zigzag course, 

 together with some loops, pursued during the next 1\ days. 

 As tha leaf continued to move all the time to the left, it is 

 evident that the zigzag line represents many circumnutations. 



(6.) Camellia Japonica (Camelliaoese, Fam. 32).— A youngish 

 leaf, which together with its petiole was 21 inches in length and 

 which arose from a side branch on a tall bush, had a filament 

 attached to its apex. This leaf sloped downwards at an angle 

 of 40° beneath the horizon. As it was thick and rigid, and its 

 16 



