site for the explanation of phenomena, all which necessarily tend to complicate the theory of horticulture, it seems better strictly to confine our attention to the action of the simplest vital forces; for the general nature of these has been undoubtedly ascertained, and is easily understood by every class of readers. It is certain, for instance, that plants breathe, digest, and perspire; but it may be a question whether the exact nature of their respiration, digestion, and perspiration is beyond all further explanation; it is therefore better to limit our consideration to the naked fact, which is all that it imports the gardener to know, without inquiring too curiously into those phenomena. For it must always be remembered that the object of a work like the present is not to elucidate the laws of vegetable life in all their obscure details, but to teach, to those acquainted with the art of gardening, what the principles are upon which their practice is founded.

4. In order to attain this end it is necessary, in the first place, to explain briefly, but distinctly, the nature of those vital actions which have a direct reference to cultivation; omitting every thing that tends to embarrass the subject or which is not susceptible of a direct practical application; and in the next place, to show how those facts bear upon the routine of practice of the horticulturist, by making them explain the reason of the treat

ment which is employed in various branches of the gardener's art.

5. The first part of this work will therefore embrace the principal laws and facts in vegetable physiology, as deduced from the investigations of the botanist; and the second the application of those laws to practice, as explained by the experience of the horticulturist.

6. If the laws comprehended in the first book are correctly explained, and the facts connected with them rightly interpreted, they must necessarily afford, in all cases, the reasons why one kind. of cultivation is better than another; and all kinds of practice at variance with those laws must be bad. Since, from the very nature of things, this cannot be otherwise, it follows that, by a careful consideration and due understanding of these laws, the intelligent cultivator will acquire the most certain means of improving his practice.

7. A PLANT is a living body composed of an irritable, elastic, hygrometrical matter, called tissue. It is fixed to the earth by roots, and it elevates into the air a stem bearing leaves, flowers, and fruit. It has no power of motion except when it is acted upon by wind or other external forces; it is therefore peculiarly susceptible of injury or benefit from the accidental circumstances that may surround it; and, having no free agency, it is above all other created beings suited to acknowledge the power of man.

8. In order to turn this power to account, it is necessary to study the manner of life which is peculiar to the vegetable kingdom, and to ascertain what the laws are by which the numerous actions essential to the existence of a plant are regulated. It is, moreover, requisite that the causes which modify those actions, either by increasing or diminishing their force, should be understood.

9. The vital actions of plants have so little re

semblance to those of animals, that we are unable to appreciate their nature in even the smallest degree by a reference to our own sensations, or to any knowledge we may possess of animal functions. Nor, when we have thoroughly studied the phenomena of vegetation, are we able to discover any analogies, except of a general and theoretical nature, between the animal and vegetable kingdoms. It is therefore necessary that plants should be studied by themselves, as an abstract branch of investigation, without attempting to reason as to their habits from what we know of other organic beings; and consequently we are not, in this part of Natural History, to acknowledge any theory which is not founded upon direct experiment, and proved by the most satisfactory course of enquiry.

10. In discussing this subject, it will be most convenient for my present purpose, if I divide the matter into the heads of, 1. Germination; 2. Growth by the Root; 3. Growth by the Stem; 4. Action of the Leaves; 5. Action of the Flowers; and, 6. Maturation of the Fruit. By this means the life of a plant will be traced through all its principal changes, and it will be easy to introduce into one or other of these heads every point of information that can be interesting to the cultivator; who will be most likely to seek it in connexion with those phenomena he is best acquainted with by their effects.

11. A SEED is a living body, separating from its parent, and capable of growing into a new individual of the same species. It is a reproductive fragment, or vital point, containing within itself all the elements of life, which, however, can only be called into action by special circumstances.

12. But while it will with certainty become the same species as that in which it originated, it does not possess the power of reproducing any peculiarities which may have existed in its parent. For instance, the seed of a Green Gage plum will grow into a new individual of the plum species, but it will not produce the peculiar variety called the Green Gage. This latter property is confined to leaf-buds, and seems to be owing to the seed not being specially organised after the exact plan of the branch on which it grew, but merely possessing the first elements of such an organisation, together with an invariable tendency towards a particular kind of developement.