94 



THE LEAF. 



The ascidia thus formed are always full of water, in which insects are clro\\Tied. 

 being prevented from escaping by the deflexed hairs at the mouth. 



246. The Nepenthes is a native of tlie East Indies. Its proper leaves are ses- 

 sile and lanceolate. The midrib extends beyond the apex, like a tendril, to the 

 length of six or eight inches. The extremity of this tendril is inflated into a hol- 

 low vessel similar to a pitcher, and usually contains about half a pint of pure 

 ■water. It is furnished with a leafy lid, connected to it by a ligament which ex- 

 pands or contracts according to the state of the atmospliere, so that the cup is 

 open in damp weather to receive moisture from the air, and closed in dry wcathei- 

 to prevent its evaporation. 



FIG. 34. — Ascidia. 1, Sarraceiiia purpurea ; 2, Nepenllies distillatoria ; 3, Dischidia R:if- 

 flesiana. 



247. Another wonderful provision of this kind is observed in a plant growing 

 in the forests of India, called Dischidia. It is a twining plant, ascending the tall 

 trees to the distance of 100 feet from its roots, and destitute of leaves except near 

 its top. These cannot, therefore, it would seem, derive much nourishment from 

 the earth. The pitchers seem fonncd of a leaf with its edges rolled towards eacli 

 otlier, and adlierent, and its upper end, or mouth, is open to receive ■whatever 

 moisture may descend into it, of which there is always a considcraTjle quantity. 

 But the greatest marvel in its structure is yet to be described. Several bundles 

 of absorbent fibres, resembling roots (142, b), are sent out from the nearest parts 

 of the stem and enter the pitchers and spread tliemselves through the cavity. 

 The design of this apparatus scarcely needs be mentioned. 



248. The leaf of Venus' fly-trap (Diontea muscipula), native at the south, is 

 al.so of a very curious eonstniction. At the extremity of each leaf are tAvo lobes, 

 bordered with spines. In the cavity between the lobes are several sharp points 

 projecting upwards, and a gland which secretes a liquor atti-active to insects. But 

 when an unlucky fly, in searcli of food, alights upon it, the irritable lobes instantly 

 close and impale him in their fatal embrace. 



249. Stipules are certain leaf-like expansions situated on 

 each side of the petiole, at its base. They are membraiioiLs, 

 leathery, or spiny. They do not occur in every plant, bnt are 

 pretty uniformly present in each plant of the same natural order 

 Ex. pea, rose, Viola tricolor. 



250. Stipules ai-e generally supposed to be accessory kavcs, although their 



