Sensation in Plants. 143 



lower animals. With plants an astonishingly small stimulus 

 suffices ; and even with allied plants one may be highly 

 sensitive to the slightest continued pressure, and another 

 highly sensitive to a slight momentary touch. The habit 

 of moving at certain periods is inherited both by plants and 

 animals ; and several other points of similitude have been 

 specified. But the most striking resemblance is the localisa- 

 tion of their sensitiveness, and the transmission of an 

 influence from the excited part to another which conse- 

 quently moves. Yet plants do not of course possess nerves 

 or a central nervous system ; and we may infer that with 

 animals such structures serve only for the more perfect 

 transmission of impressions, and for the more complete 

 intercommunication of the several parts.' 



But as if to approach more nearly the feelings of Dr. 

 Percival, he says at the end : * It is hardly an exaggeration 

 to say that the tip of the radicle thus endowed, and 

 having the power of directing the movements of the ad- 

 joining parts, acts like the brain of one of the lower animals ; 

 the brain being seated within the anterior end of the body, 

 receiving impressions from the sense-organs, and directing 

 the several movements.' 



After all, and even after reading Darwin's book on 

 the motion of plants, we cannot be held to be nearer than 

 Wordsworth, who says in * Lines written in Early Spring ' : 



Through primrose tufts in that sweet bower, 



The periwinkle trails its wreaths ; 

 And 'tis my faith that every flower 



Enjoys the air it breathes. 



The budding twigs spread out their fan, 



To catch the breezy air ; 

 And I must think, do all I can, 



That there was pleasure there. 



