Chap. IV. CIECUMNUTATION 201 



CHAPTEK IV. 



The CiBOCMNiTATiN'G Movements op the SEVEnAL paets of 

 Mature Plants. 



Ciroumnutation of stems : concluding remarks on— Ciicumnutatioii of 

 stolons : aid thus affmded in winding amongst the stems of sur- 

 rounding plants — Circumnutation of flower-stems — Circumnutation 

 of Dicotyledonous leaves — Singular oscillatory movement of leaves 

 of Dioniea— Leaves of Cannabis sink at night — Leaves of Gymno- 

 sperms — Of Monocotvlcdons — Cryptogams — Concluding remarks 

 on the circumnutation of leaves ; generally rise in the evening and 

 sink in the morning. 



We have seen in the first chapter that the stems of all 

 seedlings, whether hypocotyls or epicotyls, as well as 

 the cotyledons and the radicles, are continually cir- 

 cumnutating — that is, they grow first on one side and 

 then on another, such growth being probably preceded 

 by increased turgescence of the cells. As it was 

 unlikely that plants should change their manner of 

 growth with advancing age, it seemed probable that 

 the various organs of all plants at all ages, as long as 

 they continued to grow, would be found to circmn- 

 nutate, though perhaps to an extremely small extent. 

 As it was important for us to discover whether this 

 was the case, we determined to observe carefully a 

 certain number of plants which were growing vigor- 

 ously, and which were not known to move in any 

 manner. We commenced with stems. Observations 

 of this kind are tedious, and it appeared to us that it 

 would be sufiicient to observe the stems in about a 

 score of genera, belonging to widely distinct families 

 and inhabitants of various countries. Several plant* 



