CARNIVOROUS PLANTS 



137 



are in contact with the insect that take part in its digestion and 

 absorption, for all the others gradually alter their position from the 

 moment when any nitrogenous body, be it a fragment of flesh or an 

 insect, touches any of them. All begin to curve slowly towards the 



Fig. 26. The Sundew {JDrosera rotundifilia), 

 aftei- Kernel-. 



Fio. 27. A leaf of the Sundew, 

 with half of the tentacles curved 

 in upon a captured insect ; en- 

 larged 4 times. 



stimulating object (Fig. 37J, so that, after one to three hours, all the 

 tentacles have their heads towards it, and collectively pour out their 

 digestive juice upon it. 



The sundew grows in marshes, as, for instance, those of the Black 

 Forest, and also on the moss-covered ridges there, and it is easy to 

 observe that a leaf often shows not merely a single gnat, midge, or 

 little dragon-fly, but several, sometimes as many as a dozen. In this 

 case, again, the value of the arrangement from the point of view of 

 nourishment can be no inconsiderable one. 



In the case of the sundew we are obviously face to face with an 

 exceedingly complex adaptation, for not only is there a secretion 

 of the peculiar digestive juices, which occur only in carnivorous 

 plants, but the secreting tentacles are actively motile. That the 

 tentacles more remote from the captive may be excited to curve 

 towards it, it is necessary that the stimulus exerted by it on the 

 heads of the tentacles connected with it be conveyed to the base, and 



I. K 



