226 FREAKS OF PLANT LIFE. 



power of moving themselves in response to a touch, 

 either by elevation or depression, such movement 

 being independent of another motion, termed the 

 " sleep of plants," which is exhibited as daylight 

 declines and night comes on, by the gradual fold- 

 ing or closing of leaves. There is undoubtedly an 

 intimate relationship between the phenomena of 

 motion in leaves when touched, and in those which 

 close spontaneously on the decline of light, and also 

 in such plants as turn themselves towards or away 

 from the sun. Nevertheless, for convenience, we 

 have preferred to write separately of " sensitive 

 plants," of the " sleep of plants," and "' heliotropes," 

 or " sun-turners." 



It is needless to explain that sensibility, as 

 implied in the term " sensitive plants," does not 

 exist in the vegetable kingdom in the same manner 

 as in the animal. Without brain, and without 

 nervous system, that which we characterize as 

 sensibility does not exist. Yet there is an apparent 

 sensibility to external impressions, and there is also 

 the power of transmitting impressions from one part 

 of the plant to the other. Who will attempt, and 

 how is the limit to be defined to sensibility, or what 



M. sensitiva, M. casta, jEschyji07nene sensitiva, ^. indica, jE. 

 pujnila, Smithia sensitiva, Desmanthus stoloftifer, D. triqueter, 

 D. lacustris, Oxalis sensitiva, and, in a small degree, O. stricta, 

 0. acetosella, 0. corniculata and 0. Deppei. 



