Fig. 21. Venus's Fly-trap (Dioncea muscipula), a carnivorous 

 plant. The leaves are sensitive to contact, and in the undisturbed 

 condition are expanded. When either of the three small hairs 

 situated on each half of the upper surface of the leaf are irritated 

 by contact with a small insect, the two halves of the leaf close 

 together and remain closed until the irritation has ceased. (Natural 

 size. ) 



