86 THE VEGETATIVE FUNCTIONS OF PLANTS 



therefore, all insoluble stored foods must be converted 

 into soluble substances and dissolved. The process of 

 converting an insoluble food into a soluble substance and 

 dissolving it is digestion. This change, like the various 

 processes in photosynthesis, is brought about by various 

 enzymes, which have the power of converting insoluble 



FIG. 63. Venus's flytrap (Dioncea muscipula). Insects are captured 

 by the rapid closing together of the two valves of the leaf-blade. When 

 the valves come together the rigid marginal teeth interlock, making escape 

 impossible. The digestive enzyme is secreted by glands distributed over 

 the surface of the valves. _ (After John Ellis.) 



starch, proteins, and fats, into soluble substances. Starch 

 is converted by diastase (one of the earliest known enzymes) , 

 proteins by proteases, and fatty substances (lipoids) by 

 lipase. 



