VICE-SECRETARY OF THE HORTICULTURAL SOCIETY OF LONDON,
AND PROFESSOR OF BOTANY IN UNIVERSITY COLLEGE.

66 Though I am very sensible that it is from long experience chiefly that we are to
expect the most certain rules of practice, yet it is withal to be remembered that
the likeliest method to enable us to make the most judicious observations, and to
put us upon the most probable means of improving any art, is to get the best in-
sight we can into the nature and properties of those things which we are desirous
to cultivate and improve." - Hales's Vegetable Statistics, i. 376.

LONDON:

PRINTED FOR

LONGMAN, ORME, BROWN, GREEN, AND LONGMANS,

PATERNOSTER-ROW.

TO

THE MEMORY

OF

THOMAS ANDREW KNIGHT.