THE VEGETABLE KINGDOM. 403 



ancients. Theophrastus makes mention of it, but we must 

 come to the epoch of Mariotte to reach the demonstration 

 of this phenomenon which the Greek botanist had only 

 pointed out. The French philosopher attained this re- 

 sult by means of a very simple experiment. He took a 

 bifurcated branch, and placed one part of it in a vessel 

 filled with water, while the other remained exposed to 

 the air. The water absorbed by the former sufficed to 

 keep the latter green and fresh for a long time. Therefore 

 the one absorbed for the other. 



We must not omit stating that there are even certain 







P" 



223. Al^sorption by the Leaves. Mariotte's experiment. 



plants in which this function is entirely displaced ; the 

 task is confided to the stem only. This is the case with 

 the cactuses — strange existences — which consist solely of a 

 monstrously swollen stem covered with spines. GroAvin, 

 only among rocks and sands parched by the sun, Avhere all 

 other plants around them wither into dust, these corpulent 

 plants exhibit a freshness which is inexplicable. By some 

 secret unknown to the myriads of different kinds the 

 desiccated corpses of which surround them, they contrive 

 to imbibe fi^om the atmosphere the abundance of water 



