THE VEGETABLE KINGDOM. 477 



pulse of vegetable life, in the other the plant only with- 

 draws itself from injur)^ when it is irritated. 



Under the influence of light and temperature plants 

 take on various movements. So great is the action of 

 these upon the organism that it is entirely changed. This 

 is what we see happen in their sleep, which, as we have 

 seen, prevents certain species from being recognized, and 

 totally changes the look of a meadow or forest. 



It is particularly in the leaves that we meet this re- 

 markable phenomenon, which approximates plants so 

 much to animal life. 



In this respect the Oscillating Desmodia {Desmodia 

 oscillans) ought to occupy the first place; the mobility 

 observed in it surpasses enormously that of many inferior 

 animals. It is an Indian plant of the family of Legu- 

 minosfe, each leaf of which is composed of a great ter- 

 minal leaflet and two smaller ones which approximate 

 at its base. When the sun falls upon the Desmodia these 

 two leaflets go through a very remarkable series of con- 

 tinuous oscillations. They advance and retire successively 

 one from the other with a trembling jerking movement, 

 which exactlyresembles that of the seconds-hand of a watch. 

 There is such a similarity between these movements and 

 those of animals that they cease under the influence of 

 the same agents. If a plant be sprinkled with opirmi it 

 falls into a state of narcotism, and its oscillations are 

 utterly stopped. 



The activity of the Desmodia is so energetic that it is 

 not arrested in boughs which have ]:)een cut from the 

 parent plant. Broussonnet saw the leaflets of a liranch 

 which he had plunged into water move for three days 

 after. 



In the leaves of the Nepenthes the phenomenon is not 



