'That wood is a deposit in some way connected with the action of the leaves. That the quantity of wood formed is in direct proportion to the number of leaves that are evolved, and to their healthy action; and where no leaves are formed neither is wood deposited. In all plants there are two distinct, simultaneous systems of growth; the cellular, and the fibro-vascular, of which the former is horizontal, and the latter vertical. The cellular gives origin to the pith, the medullary rays, and the principal part of the cortical integument. The fibro-vascular to the wood and a portion of the bark. 'Buds are exclusively generated by the cellular system; while roots are evolved from the fibro-vascular system. 'Wood is organized matter generated by the leaves and sent downwards by them. "The opening of the anthers is not a mere act of chance, but the admirably contrived result of the maturity of the pollen, when the pollen has acquired its full development. Tubes are projected into the style by the pollen. Dr. Brown has demonstrated the universal presence of a passage thro the integuments of the ovulum at the point of the nucleus. 'It is at the point of the nucleus that the nascent embryo makes its appearance. "The contents of the pollen pass down the pollen tubes. There is a power of motion in the granules thus emitted. 'Ovula seem to be buds.' Report Brit. Assoc. in 1833, p. 27-54. LETTER XX. LETTER XXI. APPOINTMENT AND ADAPTATION OF THE SURFACE FOR THE XXI. MY DEAR SON, LETTER IN arranging and settling the surface of our earth in the diluvian commotion, it was not enough to compose and place the rocks and strata so as that they should be of that sort, and disintegrate into that state, and remain always such, as would suit and cherish the general vegetation of the globe. But as the electrical influences in all their modifications, whether as magnetism, galvanism or otherwise, and the temperature of our air and its vapours, clouds and winds, and the succession of the seasons, depend very materially on the interior strata and disposition of our subterraneous surface; it had also to be framed and regulated with a view to all the proper results, that were appointed to take place in these important respects for our benefit. But when the construction and condition of our habitable ground, had been fixed as to all its physical agencies, still other considerations were necessary in the Creator's mind, before its form and disposition should be finally determined on; and these were those points, which more immediately related to the nature and welfare of His human kind. Nothing as to them either could or would be left to chance, or to the mere material course and sequences of things XXI. irrespective of them; or no specific, no permanent, LETTER no rational and no comfortable form and state of human nature could arise. It was therefore essential for the Almighty omniscience, which could do whatever it should chuse to do, and without whose appointing and framing will no mode of being could exist, to determine what the numbers, the localities, the social state, the habits, the pursuits, the history and the general characters of the renewed race of mankind were to be, in order that so far as they would be produced, governed or affected by the nature and influence of the surface they were to dwell on, to cultivate and to obtain their subsistence and conveniences from; it might be made such as would cause and promote what the divine economy had intended should, on all these points, be provided for and produced. The NUMBERS of human beings who should, at every period, be living at the same time on the earth, must have been decided on in the Divine Mind before the new surface was settled; because, on this would depend, whether the whole superficies of its circumference, or only a part of it, and in that case, how much of it, should be occupied with their population, and adapted to their use. If as many were to be coexisting upon it, as a globe of twenty-four thousand miles in circuit could contain and nourish, then, every portion of its upper soil must be made and kept in such a state as would supply the habitable locality and the proper vegetation; but, if man was not to replenish the whole area of the circular expanse, it would then be sufficient if so much only was made cultivable and fitted for his residence, as his appointed numbers should require. The space to XXI. LETTER be prepared and appropriated by man, would be governed by the intended quantity of his population, that were, from time to time, to be contemporaneous. A few would require small room, multitudes much more. If the numbers were to be gradually augmented, the fitted surface might be as gradually extended; but at all events the highest quantity meant to be co-tenants, must have been adverted to, that the whole space, which would be in the fullest diffusion wanted, might be provided and made ready. These recollections may satisfy us, that neither the increase and amount of the human population, nor the state and form of our globular surface have been left to be what chance, or the undirected movements of nature, might make them; but that they must, from the beginning of our renewal, have been the subject of the Divine deliberation and adjusting care. We see this immediately in one striking circumstance. The ocean has been made to occupy nearly threefourths of our surface. An event of this magnitude could be no accident. It must have been resolved from the re-commencement of things, that about onefourth only of the earth's surface should be inhabited by man, and that the remainder should be covered by the seas. Here was, from the time the Deluge ceased, an express limitation of the population of mankind, and of all land vegetation, and of the animals who subsist upon it. At that time or before, it was fixed that neither of these should be as many as the globe would contain, but only, at the utmost, one-fourth of that possible number. The ocean was in this respect made the limiting and confining instrument; its waves, as they rolled and expanded, spread every where the prohibition, and maintained XXI. it, that man and all terrestrial life should never LETTER multiply nor extend beyond one-fourth of the surface of the planet, in which he was stationed. But was it also settled that the human race should ever increase to the full population, which that restricted space allows? Was man ever to multiply into such a multitude of human beings as one-fourth part of the surface could maintain? The facts which have occurred, enable us at once to answer, that it never has been the divine intention, that mankind should ever enlarge into such a productivity and quantity as this. The vegetable kingdom has been permitted and enabled to have this extent of dissemination, and some classes of the animated world, attend its herbs and trees wherever they arise. Not so mankind. A proportion, and that a small one, of the habitable surface is that which they have been designed to till and occupy; for, if they had not been restricted to this minor number, the amount of their possible population, which might have subsisted at the same time on the fourth part of the earth, would have been a vast multiple of their present number. On this point we have sufficient data to reason correctly from. From all that history presents to us we may justly conclude, that the earth never had, at one time, a larger proportion of human kind than it now possesses. Malte Brun has reckoned the present population of the world at six hundred and fifty millions; some think it more, and others calculate it to be less.' A thousand millions have been mentioned, apparently for no other reason than the convenience of a round number.-M. Malte Brun reduces the amount to 650,000,000. We think his enumeration for |