101 



climbing. No force can make one twist round a pole 

 from left to right, if its natural direction be from right 

 to left. If a garden pot be divided by a vertical par- 

 tition, and one half filled with a poor sterile earth, 

 and the other moiety with a rich fertile soil, a gera- 

 nium or other plant placed in this pot, with some 

 of its roots over the sterile soil, and the rest of the 

 roots over the fertile soil, those over the first named 

 portion will gradually change their direction until 

 they can also get into the richer pasturage. Instances 

 have been known of the roots of trees piercing and 

 destroying walls in their efforts to attain a more pre- 

 ferable soil than that in which they were planted. 

 M. Saussure relates that he placed some plants of 

 Polygonum persicaria and Bidens cannabina in water 

 containing acetate of lime in solution. These plants 

 then imbibed, with the water, a portion of this salt ; 

 but when they had the opportunity of selection given 

 them, by dissolving in the water some common salt, 

 glauber salt, and acetate of lime, they absorbed the 

 two first named, but rejected the latter entirely. 

 {Saussure s Recherches, 247 — 261.) 



From the foregoing facts, without arguing that 

 they demonstrate sensation to exist in plants as acute 

 as that possessed by the higher or more perfect 

 classes of animals, yet they certainly are satisfactory 

 evidence that plants probably are nearly as sensient 



