INTRODUCTION.

ÂGrICULTURE and GARDENING, though of fuch great utility in: producing the nutriment of mankind, continue to be only Arts, confifing of numerous detached fa@s and vague opiñions, without a true theory to conneét them, or to appreciate their analogy; at a time when many parts of knowledge of much inferior confequence

have been nicely arranged, and digefted into Sciences.

Our imperfeét acquaintance with the phyfology and economy of vegetation is the principal caufe of the great immaturity of our know- ledge of Agriculture, and Gardening. I fhall therefore firft attempt a theory of vegetation, deduced principally from the experiments of Hales, Grew, Malpighi, Bonnet, Du Hamel, Buffon, Spallanzani, Prieftley, and the Philofophers of the Linnæan School, with a few obfervations and opinions of my own; fome of which have in part already appeared in Zoonomia, and in the notes to the Botanic Gar- den, but are here correéted and enlarged. To the former of which. Works[hope this may be efteemed a fupplement, as it is properly a: continuation of the fubje@.

My