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 pink, 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 from 
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 pierces into the 
stigmatic tissue, lengthens thei'e, and conveys the vivifying 
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 afterwards impelled through 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 northern 
climates, and of a large part of the herbage of the same coun- 
tries — modified, of course, by peculiarities of structure and 
R 
