412 



PARASITES AND CARNIVOROUS PLANTS 



case of those caught by the sundew, after which the trap reopens 

 and is ready for fresh captures. 



383. Object of catching animal food. It is easy to under- 

 stand why a good many kinds of plants have taken to catch- 

 ing insects and absorbing the digested products. Carnivorous, 

 or flesh-eating, plants belong usually to one of two classes as 





i 



Aial 



FIG. 314. Venus flytrap (Dionoea muscipula) 



regards their place of growth ; they are bog plants or air plants. 

 In either case their roots find it difficult to secure much nitrogen- 

 containing food, that is, much food out of which proteid mate- 

 rial can be built up. Animal food, being itself largely proteid, is 

 admirably adapted to nourish the growing parts of plants, and 

 those which could develop insect-catching powers would stand 

 a far better chance to exist as air plants or in the thin, watery 

 soil of bogs than plants which had acquired no such resources. 





