SENSATION IN PLANTS 



cally touching any part, is at all times without 

 effect. 



In these and in many other plants provided with 

 similar sensitive contrivances the plasmodium may 

 be seen in motion in the vessels that appertain to the 

 specialized organs. It appears to fulfill the functions 

 that the nerves do in animals when they carry to and 

 from the brain the impressions produced by the 

 senses, and subsequently transfer therefrom the will 

 power that controls muscular contraction. The 

 mechanism, however, that would seem to be required 

 for such substitution has never been observed, though 

 it is said that electric currents have been noted, 

 which might have some analogy with the electric- 

 motor character of the nerves and muscles. 



No structures or organs are known in plants that 

 correspond to the cerebro-spinal nervous centres in 

 animals. The conversion of the purely chemical and 

 physical metamorphoses in the higher plants as well 

 as in the lower orders, into the inexplicable phenom- 

 ena of sensation, and voluntary motion, seems not 

 to be relegated to a special division of the plasmodium, 

 differentiated for that function, but to be the general 

 attribute of the whole plasma. It shows itself as 

 active not only in the specially sensitive plants above- 

 named, but also in the petals of flowers, in the move- 

 ment of leaves, and in the translatory motion of the 

 18 273 



