150 FREAKS OF PLANT LIFE. 



CHAPTER VII. 



GYRATION OF PLANTS. 



It is only very recently that any regular and 

 systematic investigation has been pursued to ascer- 

 tain the causes and mode of action in certain 

 phenomena of motion in plants. By whatever names 

 these motions may have been designated, they 

 appear to resolve themselves into modifications of 

 one simple type of movement to which the name of 

 " circumnutation " has been applied. This movement 

 in its ordinary form consists in the revolution of the 

 growing point, which has been described in the 

 following terms : — " If we observe a circumnutating 

 (or revolving) stem, which happens at the time to be 

 bent, we will say towards the north, it will be found 

 gradually to bend more and more easterly until it 

 faces the east, and so onwards to the south, then to 

 the west and back again to the north. If the move- 

 ment had been quite regular the apex would have 

 described a circle, or rather, as the stem is always 

 growing upwards, a circular spiral. But it generally 

 describes elliptical or oval figures ; for the apex after 

 pointing in any one direction commonly moves back 



