402 THE UNIVERSE. 



found at their ends, sometimes constantly open, sometimes 

 closing and opening by means of a movable lid. 



In the first rank we ought to place the famous Nepenthes 

 distillatoria, or pitcher-plant, met with in Southern Asia. 

 Its leaves display a strong mid-rib, which extends beyond 

 the blade, and ends in an elegant cylindrical cup, provided 

 with a hinged lid, which spontaneously opens and closes, ac- 

 cording to the state of the atmosphere. During the night 

 this lid sinks down, and hermetically closes the little vase, 

 which then fills with limpid water, exhaled by its walls. 

 During the day the lid is raised, and the fluid evaporates 

 more or less completely. The beneficent nepenthe has 

 often quenched the thirst of the Indian lost in his burning 

 deserts. 



In the marshy forests of Southern America, Providence 

 has intrusted this task to another distilling plant, the Purple 

 Sarracenia, the structure of which is no less eccentric. Its 

 leaves, uniting at their edges, are transformed into elegant 

 amphorae, the narrow opening of which is surmounted by 

 an ample green auricle, decorated with scarlet-red veins, to 

 which the species owes its name. These cups, presents 

 from the empire of Flora, and which rise from spot to spot 

 at the feet of the traveller, are filled with pure and de- 

 licious water, for the benefit of which he is all the more 

 grateful that he is encircled by nothing but marshes, the 

 water of which is lukewarm and nauseous. 



Generally, transpiration from the leaves only takes place 

 by their under surface. Knight demonstrated this by a 

 very simple experiment. He inclosed a vine leaf between 

 two plates of glass, and observed that only the plate in con- 



