202 CIECUMXUTATION OF STEMS. Chat. IV 



were selected whicli, from being woody, or for othoi 

 reasons, seemed the least likely to circumnutate. The 

 observations and the diagrams were made in tlie 

 manner described in the Introduction. Plants in pots 

 were subjected to a proper temperature, and whilst 

 being observed, were kept either in darkness or were 

 feebly illuminated from above. They are arranged 

 in the order adopted by Hooker in Le Maout and 

 Decaisne's ' System of Botany.' The number of the 

 family to which each genus belongs is appended, as 

 this serves to show the place of each in the series. 



(1.) flerU umhellaia (Cruciferse, Fam. 14).— The movement of 

 tlie stem of a young plant, 4 inclies in height, consisting of 

 four iiiternodos (the hypocotyl included) besides a large bud 



Fi? 70. 



iUrts um^'ellata : circumnutation of stem of young plant, traced from 

 8.30 A.M. Sept. 13th to same hour on following morning. Distance of 

 .<=ummit of stem beneath the horizontal glairs 7'6 inches. Diagram 

 reduced to half of original size. Movement as here shown magnlHei 

 between 4 and 5 times. 



on the summit, was traced, as here shown, during 24 h. 

 (Fig. 70). As far as w& could judge the uppermost inch alone 

 of the stem circumnutated, and this in a simple manner. Tlie 

 movement was slow, and the rate vci-y unequal- at different 

 limes. In part of its course an iiTCgnlar ellipse, or rather 

 triangle, was completed in 6 h. 30 m. 



(2 ) lirasska Uerncea (Cruciferffi). — A very young plant, bearing 

 tliroe leaves, of which the longest was only thret-quarters of an 

 inch in length, was placed under a microscope fm-uished with 

 an eye-piece micrometer and the tip of tlie largest leaf was 



