246 FREAKS OF PLANT LIFE. 



leaflet began to fall. The descent was accomplished' 

 by six descending steps, that is, by falls succeeded by 

 a slight rising, so as to cause a kind of oscillation, 

 each fall being greater than the rise. The plant was 

 again shaded, and a long slow rise commenced, which 

 continued until the sunlight was again admitted. It 

 is unnecessary to enter into all the minute details of 

 this experiment, the object being to show that a rise 

 and fall of the leaflets took place as a consequence of 

 the increase or diminution of direct sunlight. 1 In 

 another chapter we have alluded to the " sensitive " 

 movements of another exotic fruit-tree belonging to 

 the same genus. 



The leaves of the common clover ( Trifolium repens) 

 are similar in size and form to those of the wood- 

 sorrel, but of a darker green. Their movements 

 nevertheless are quite dissimilar, for the leaflets instead 

 of descending at night, rise and fold over each other so 

 that the under surface is exposed. As evening ap- 

 proaches the two side leaflets twist themselves and 

 move towards each other until their upper surfaces 

 come into contact. At the same time they bend 

 downwards until their midribs form an angle of about 

 forty-five degrees with the upper part of the footstalk. 

 The terminal or middle leaflet rises without twisting, 

 and bends over until it rests upon and forms a kind of 



1 Darwin, " Movements of Plants," p. 3.32. 



