SPECIAL SENSES 



characteristic sense in well nigh every animal, 

 and in the larger number is especially devel- 

 oped and intensified in certain organs that 

 may be appropriately termed organs of touch. 



If we return to plants, we find this simplest 

 and most generalized of senses, with some 

 notable exceptions, practically absent. In a 

 few instances, as in the tendrils of certain 

 plants, there is a marked, sometimes a mar- 

 velous sensitiveness to touch, but it is con- 

 nected neither with the attainment of safety 

 nor of food. Only in the very few and excep- 

 tional cases of insectivorous plants, like the 

 sundews, has the plant acquired a sense of 

 touch to aid it in detecting and grasping food. 

 But sensitiveness to contact is not a common 

 property of plants. 



An inquiry into the conspicuous difference 

 between the attitude of the animal and the Trend of sense 

 plant toward objects external to itself must development 

 reveal some of the reasons underlying the 

 trend of sense development. And first of all 

 it must be noted, that when the animal de- 

 tects something inimical to its safety, it 

 moves away from the offending object, a pro- 

 cedure impossible to the plant with its anchor- 

 age of roots. Were the aspen quaking through 

 fearof impending calamity, it could not escape 

 by flight, or by the displacement of its body 

 by so much as an inch. In another, and even 



