Page:An introduction to physiological and systematical botany (1st edition).djvu/272

 242 from the returning sap, are confined to their own purposes. As soon as these are accomplished, a decided separation of vessels takes place, and the ripe fruit, accompanied perhaps by its stalk, falls from the tree. Dr. Hales tried in vain to give any flavour to fruit by the most penetrating and volatile fluids conveyed through the sap-vessels; for the laws of secretion are absolute in the organs of the flower, and their various results are, if possible, more strikingly distinct than even those we have contemplated in the leaves.

It is scarcely necessary to repeat that the fructification is essential to vegetables. A plant may be destitute of stem, leaves, or even roots, because, if one of these parts be wanting, the others may perform its functions, but it can never be destitute of those organs by which its species is propagated. Hence, though many individual plants may be long without blossoms, there are none, so far as nature has been thoroughly investigated, that are not capable, in favourable circumstances, of producing them, as well as seeds; to whose perfection the blossoms themselves are altogether subservient.