THE NERVOUS MECHANISM. OF PLANTS 401 
resulted in the usual place. If we turn to the reaction of the 
leaf of Dionza 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. 160), 
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, 160.—LEar or Dionea muscipula. 
1, open; 2, closed; 8, 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 
senge-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 as we descend in the scale, till in some it goes 
probably little further than the power of appreciating light. 
26 
