268 



CHAP. XXV. DIURNAL MOVEMENT OF MIMOSA 



Fourth phase. — There is a fall of the leaf during the 

 rise of temperature from thermal dawn to thermal noon. 



Fig. 155. Diurna record of leaf of Mimosa in summer and in winter. 



Leaf rises from 2 to 5 p.m., when there is a spasmodic falL Leaf 

 re-erects itself from 9 p.m. to 6 a.m., after which there is a 

 gradual fall till 2 p.m. with pulsation. The uppermost record 

 gives temperature variation, up-curve representing fall of 

 temperature and vice versa. 



The uniformity of the fall is, however, interrupted by one 

 or more pulsations in the forenoon, which are more frequent 

 in summer than in winter. 



It will thus be seen that the difference between the 



