94 



THE LEAF. 



The ascidia thus formed are always full of water, in which insects are drowned, 

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



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

 sile and lanceolate. The midvein 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 atmosphere, so that the cup is 

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

 to prevent its evaporation. 



FIG. 34. — Ascidia. 1, Sarraceiiia purpurea ; 2, Nepentlies distillatoria ; 3, Dischidia Raf- 

 flesiana. 



247. Another wonderful provision of this kind is ohsen-ed in a plant gi-owing 

 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 each 

 other, and adherent, and its upper end, or mouth, is open to receive whatever 

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

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

 of absorbent fibres, resembling roots (142, 6), are sent out from the nearest parts 

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

 The design of this apparatus scarcely needs be mentioned. 



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

 also of a veiy curious constniction. At the extremity of each leaf are two lobes, 

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

 projecting upwards, and a gland which secretes a liquor attractive to insects. But 

 when an unlucky fly, in search 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 membranous, 

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

 pretty uniformly present in each plan+ of the same natural order 

 Ex. pea, rose, Viola tricolor. 



250. Stipules are generally supposed to be accessory kai^cs, although their 



