3S2 



MODIFIED CIKCUMNUTATION. 



Chap. A'IL 



do not fully apply to the small leaf here figured. The pinnie 

 move forwards and at the same time sink downwards, whilst 

 the main petiole rises considerably. With respect to the degree 

 of movement : the two terminal pinnre of one specimen formed 

 together an angle of 100° during the day, and at night of only 

 38°, so each had moved 31° forwards. The penultimate pinnjB 

 during the day formed together an angle of 180°, that is, they 

 stood in a straight line opposite one another, and at night each 

 had moved 65° forwards. The basal pair of pinnae were directed 



Fig. 160. 



A. B. 



Acacia Famesiana. A, leaf during the diiy ; B, the same leaf at eight. 



during the day, each about 21° backwards, and at night 38° 

 foi wards, so each had moved 59° forwards. But the pinnse at 

 the same time sink greatly, and sometimes hang almost perpen- 

 dicularly downwards. The main petiole, on the other band, 

 rises much : by 8.30 p.m. one stood 34° higher than at noon, 

 and by 6.40 a.m. on the following morning it was still higher 

 by 10°; shortly after this hour the diurnal sinking move- 

 ment commenced. The course of a nearly full-grown leaf was 

 traced during 14 h ; it was strongly zigzag, and apparentlj 



