IJ.— THE DIURNAL MOVEMENT OF THE LEAF OF 

 MIMOSA 



By 



Sir J. C. BosE. 



In the standard curve of nyctitropic movement under 

 thermo-geotropism described in a previous paper, the diurnal 

 record consisted of an up-curve from thermal-noon to 

 thermal-dawn, and a down-curve from the thermal-dawn to 

 thermal-noon. The responding organ, which may be an 

 inclined stem or a horizontally spread petiole, underwent an 

 erection during the decline of temperature, and a fall with 

 the rise of temperature. The diurnal record of the Mimosa 

 leaf appears, however, to be totally different. 



Experiment 220. — I obtained the diurnal record of 

 Mimosa (Fig. 210) for twenty-four hours commencing at 

 2 p.m. which is the thermal-noon. The summer and winter 

 records are essentially the same ; the only difference is in 

 the greater vigour of movement exhibited by summer 

 specimens. The diurnal movement of the leaf is very 

 definite and characteristic ; for the curves taken five years 



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