DIURNAL MOVEMENT OF MIMOSA 



585 



its autonomous pulsations for more than seven days. I 

 reproduce two sets of reconls (Fig. 212) for 24 hours each, 



Fig. 212. — Continuous record of automatic pulsation of Mimosa leaf. The two 

 series are for the dfst and the third day. 



obtained on the first and the third day. Tlie average period 

 of a single pulsation is slightly less than six hours ; but 

 this is likely to be modified by the age of the specimen 

 and the temperature of the environment. 



One of the factors that determines the diurnal movement 

 of the leaf is the immediate and after-effect of light. The 

 movement under the action of light, is modified by 

 the intensity and duration of illumination. The experi- 

 mental investigation of the subject offers many diffi- 

 culties, principally owing to the al)sence of any reliable 



42 a 



