204 



CIKCUMNUTATION OF STEMS. 



Chap. IV 



aid of their sensitive petioles, but some of them also twine 

 round supports ; but even these latter species do not begin to 

 circumnutate in a conspicuous manner whilst young. The 



Fig. 72. 



Tropaolum majus (?) : circumnuUition of stem of young plant, traced on a 

 horizontal glass from 9 a.m. Dec. 26th to 10 a.m. on 27th. Movement 

 of be.id magnified about 5 times, and here reduced to half of original 

 scale. 



variety here treated of has a rather thick stem, and is so dwarf 

 that apparently it does not climb in any inanner. "We there- 

 fore wished to ascertain whether the stem of a young plant, 



consisting of two in- 

 ^^•^'' temodes, together 3-2 



inches in height, cir- 

 cumnutated. It was 

 observed during 25 h., 

 and we see in Fig. 72 

 that the stem moved in 

 a zigzag course, indicat- 

 ing circumnutation. 



(6.) Trtfolium resupi- 

 natum (LeguminosBe, 

 Fam. 75). — When we 

 treat of the sleep of 

 plants, we shall see that 

 the stems in several 

 Leguminous genera, for 

 instance, those of Hedy- 

 sarum. Mimosa, Meli- 

 lotus, &c., which are not 

 climbers, circumnutate 

 in aeon spicuous manner. 

 We will here give only a single instance (Fig. 73), showing 

 the drctunnutation of the stem of a large plant of a clover, 

 Vrifolium resupinatum. In the course of 7 h. tho stem changed 



Ti-ifoUwn res'ipinatum : circumnutation of 

 stem, traced on vertical glass from 9.30 

 A.M. to 4.30 P.M. Nov. 3rd. Tracing not 

 greatly magnifiel, reduced to half of 

 original size. Plant feebly illuminated 

 from above. 



