SENSITIVITY IN PLANTS AND ANIMALS 67 



be while the plant, on the other hand, has no such 

 power of movement. A sense of contact for this 

 purpose is thus useless to it, for, being fixed, it could 

 not benefit by its possession. The ingestion of organic 



FIG. 27. Mimosa. A, before, B, after stimulation. 

 (J Natural size. ) 



food by the animal necessitates, on its part, power 

 of movement or locomotion, so that it may seek for 

 such food (p. 78) ; the plant, on the other hand, does not 

 require to search for the raw materials, for these are 

 brought to it by atmospheric currents, or lie round 

 its roots in the soil. The animal is further liable to 

 all sorts of injuries during its search for food the 



