266 OUTLINES OF PLANT LIFE. 



(figs. 137, 226). The hinge is in reality a cushion of tissue 

 upon the back, which quickly throws the two halves of the 

 leaf together when the sensitive hairs on the inner face of 

 the trap are touched. The movement is sudden enough in 

 DioncBa to catch the slow-flying insect, or, in Andrmandia, 

 the minute water animal. The prey is prevented from escap- 

 ing by the interlocking, tooth-like lobes along the edges of 

 the leaf. Digestion and absorption of the foods follow.* 



II. Herbivorous animals. 



376. Protection. — While a really insignificant number of 

 minute animals are eaten by plants, a very large number of 

 plants find it necessary to protect themselves in some way 

 against destruction by browsing animals, insects, snails, and 

 slugs. Since the animal world relies for its food supply 

 ultimately upon the green plants, it is plain that no such 

 protective measures are completely effective. The protec- 

 tion, therefore, may be looked upon as a protection against 

 extermination rather than against injury. As protective 

 adaptations against browsing animals are usually reckoned : 



377. I. Armor, in the form of hard, leathery, sharp- 

 edged, woolly, bristly, or sticky parts, especially leaves 

 (figs. 200, 201, 202, 227); or thorns (figs. 103, 228), prickles, 

 or stinging hairs (fig. 229). 



378. 2. Distasteful or injurious substances, such as 

 volatile oils, camphors, acids tannins, alkaloids, etc. The 



* Travesties upon these strange methods of nutrition appear periodic- 

 ally in newspapers, and plants of remarkable size and forbidding aspect 

 are represented as capturing birds, animals, and even men, that ven- 

 ture into their neighborhood. It should be noted, therefore, that in all 

 cases the plants vphich capture animal food entrap only the smaller ani- 

 mals, scarcely any of them, except those caught by the pitcher plants, 

 larger than the common house-fly. 



