SOME MOOT POIXTS IX XATURAL HISTORY. 265 



sensitiveness in a very defined manner; whilst the plant 

 may, like the animal, become accustomed to stimulation, and 

 cease to show the amount of irritability it at first exhibited. 

 The contact of chemical substances with the leaflets pro- 

 duces the same effect as touch or darkness. The mimosa 

 exhibits irritation, like its animal-neighbours, on being at first 

 exposed to the fumes of chloroform ; but after a continued 

 exposure to the vapour the plant loses its sensitiveness, and 

 remains with expanded leaflets, perfectly insensible to 

 stimulus of any kind. A sensitive-plant was carried on one 

 occasion by Desfontaines in a coach. The jolting of the 

 vehicle at first produced rapid contraction of its leaves ; but 



FIG. 44. Leaves of Venus's-flytrap : a, b, leaves expanded ; c, leaf closing ; d, leaf 



closed. 



as the journey advanced, the plant, despite the shaking, 

 spread its leaflets as if it had become accustomed to the 

 movement, and as if it had lost all sense of alarm. 



More curious even than the acts of the sensitive-plant, 

 are the phenomena of sensitiveness exhibited by the Venus's- 

 flytrap (Dioncea miisripula, Fig. 44), a native of American 

 marshes. This well-known plant possesses leaves which 



