BOOK II. GENERAL CONSIDERATIONS. 241 



means of returning, all that cannot be consumed by the calyx 

 is forced onwards into the circulation of the petals, stamens, 

 and pistil. The petals unfold themselves of a dazzling white 

 tinged with pmk, and expose the stamens ; at the same time 

 the disk changes into a saccharine substance, which nourishes 

 the stamens and pistil, and gives them energy to perform 

 their functions. 



At a fitting time, the stigmatic surface of the pistil being 

 ready to receive the pollen, the latter is injected upon it fi'om 

 the anthers, which have remained in approximation to it for 

 that particular purpose. When the pollen touches the stigma, 

 the grains adhere firmly to it by means of its viscid surface, 

 then emit a delicate membranous tube, which piei'ces into the 

 stigmatic tissue, lenojthens thei'e, and convevs the vivif\'incj 

 matter contained in the pollen towards the ovules, which it finally 

 enters by means of their foramen. This has no sooner oc- 

 curred than the petals and stamens fade and fall away, their 

 ephemeral but important functions being accomplished. All 

 the sap which is afterwai'ds impelled tlu'ough the peduncle 

 can only be disposed of to the calyx and ovary, where it 

 lodges : both these swell and form a young fruit, which con- 

 tinues to grow as long as any new matter of growth is supplied 

 from the parent plant. After a certain period the juices of 

 the fruit cease to be increased by the addition of new matter, 

 its surface performs the functions of leaves in exposing the 

 juice to light and air; finally it ceases to decompose carbonic 

 acid, gains oxygen in excess, loses its green colour, assumes 

 the rich ruddy glow of maturity; the juices cease to be in- 

 fluenced by light ; the peduncle is no longer a passage for 

 fluids, but dries up and becomes unequal to supporting the 

 fruit, which at last falls to the earth. Here, if not destroyed 

 by animals, it lies and decays : in the succeeding spring its 

 seeds are stimulated into life, strike root in the mass of decayed 

 matter that surrounds them, and spring forth as new plants to 

 undergo all the vicissitudes of their parent. 



Such are the progressive phenomena in the vegetation, not 

 only of the apple, but of all trees that are natives of nortliern 

 climates, and of a large part of the herbage of the same coun- 

 tries — modified, of course, by peculiarities of structure and 



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