ASSIMILATION AND METASTASIS. 



107 



and thus furnishes a por- 

 tion of its (nitrogenous) 

 food. Venus's Fly-trap, the 

 lobes of whose leaves close 

 and capture insects when 

 the latter touch the slender 

 hairs on the upper side 

 (Fig. 223a), is likewise capa- 

 ble of digesting animal food. 

 The numerous sessile glands ^^sa 



provide the digestive secretion, and also absorb into the 

 plant the digested portions of the insects. 

 Glands, whose viscid secretion is capable 

 of digesting nitrogenous material, are also 

 found on the leaves of the Butterwort 

 (JPinguicula), which grows' on \Yet rocks and 

 damp soils. The curious little bladders 

 (Fig. 224) of the Bladderwort 

 {Utrieularia) capture small water-animals. In 

 the pitchers (Fig. 225) of the Sarraeeaia and 

 Nepenthes, insects fall and drown ; these animals, 

 by their decay, probably furnish food to be 

 absorbed by the plants. 



137. The immediate products of assimilation 

 undergo further (though but slightly understood) 

 chemical changes to form the various substances 

 found in vegetable tissue. All these changes, 

 subsequent to assimilation, are collectively 

 termed metastasis (Gr. meta, over ; istavmi, 

 to place). Metastasis is a process of oxidation ; 



Fig. 223a. Leaves of Venus's Fly-trap {Dionizct), Fig. 224. Bladder from the 

 stem of the Bladderwort ( Utricularia), slightly magnified. Fig. 225, A leaf, having 

 the form of a pitcher or cup, of Sarracenia. 



221 



223 



