284 
PHYSIOLOGY. 
BOOK II. 
peduncle, no longer a passage for fluids, 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 which 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 which are natives 
of northern climates, and of a large part of the herbage of 
the same countries, modified, of course, by peculiarities of 
structure and constitution; as in annual and herbaceous 
plants, and in those the leaves of which are opposite and not 
alternate : but all the more essential circumstances of their 
growth are the same as those of the apple tree. 
If we reflect upon these phenomena, our minds can scarcely 
fail to be deeply impressed with admiration at the perfect 
simplicity and, at the same time, faultless skill, with which all 
the machinery is contrived upon which vegetable life depends. 
A few forms of tissue, interwoven horizontally and perpen- 
dicularly, constitute a stem ; the developement, by the first 
shoot that the seed produces, of buds which grow upon the 
same plan as the first shoot itself, and a constant repetition 
of the same formation, cause an increase in the length and 
breadth of the plant ; an expansion of the bark into a leaf, 
within which ramify veins proceeding from the seat of nutri- 
tive matter in the new shoot, with a provision of air-passages 
in its substance, and of pores on its surface, enables the crude 
fluid sent from the root to be elaborated and digested until it 
becomes the peculiar secretion of the species ; the contraction 
of a branch and its leaves forms a flower ; the disintegration 
of the internal tissue of a petal forms pollen ; the folding 
inwards of a leaf is sufficient to constitute a pistil ; and, 
finally, the gorging of the pistil with fluid which it cannot 
part with causes the production of a fruit. 
In hot latitudes there exists anotlier race of trees, of which 
Palms are the representatives; and in the north there are 
many herbs, in which growth, by addition to the outside, is 
wholly departed from, the reverse taking place; that is to say, 
