THE NEKVOUS MECHANISM OF PLANTS 401 



resulted in the usual place. If we turn to the reaction of the 

 leaf of Dionaea to contact, we find that the whole leaf may 

 be somewhat roughly handled without closing, so long as 

 no contact is made with the hairs, three in number (fig. 162), 

 which arise upon a particular portion of the blade. So 

 soon, however, as one of these is touched, the leaf closes. 



It is impossible to avoid the conclusion that we have to 

 do in these instances, which are only representative ones, 



FIG. 162. LEAP OF Dioncea muscipula. 



1, open ; 2, closed ; 3, one of the sensitive spines ( x 50) ; 4, glands on 

 the surface of the leaf ( x 100). 



with a localisation of sensitiveness, or the differentiation 

 of sense-organs. If we compare them with physiologically 

 corresponding regions in the animal we find a certain 

 agreement, though it must not be pressed too far. The 

 power of sight is very complete in the higher animals, 

 partly in consequence of the highly differentiated character 

 of the eye, but in the lower animals it becomes less and 

 less perfect, till in some it goes probably little further than 

 the power of appreciating light. This power we have seen 



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