XX. LETTER of the bird and insect classes, and of so many quadrupeds, have not been less numerous or beneficent. Such care has been taken in the adjustment of soil to tree, and tree to soil, that every kind of rock that decomposes so much, as to afford any penetrable matter for roots to extend in, sustain and furnish some useful or pleasing trunks and foliage." So fitly and adaptedly has the vegetable structure been made for the earthy masses of our planet, that 'plants and trees, the roots of which are fibrous and hard, and capable of penetrating deep into the earth, will vegetate to advantage in almost all common soils that are moderately dry, and which do not contain a very great excess of vegetable matter.'" We cannot doubt, as we study the present nature of our surface, that it has been most carefully adapted to develop and nourish its intended vegetative offspring." 35 33 Thus, tho the country round Fort Providence, on the Great Slave Lake in North America, consists almost entirely of coarsegrained granite, the surface is generally naked, yet in the valleys between its hills a few spruce, aspen and birch trees grow; together with a variety of shrubs and berry-bearing plants.' Frankl. Journ. p. 209.- Three-fourths of all vines are grown on hills; and wines of the first character are made from vines that flourish among stones and pieces of rock.-No wine of tolerable quality is grown on rich and highly dressed land.' C. Redding on Wines. Between Rocky and Carp Lake the granite contains many beds of MICA SLATE, passing into clay slate; yet the country is tolerably well wooded. White spruce occupies the rocky situations, pinus banksiana the sandy spots ; aspen, the low moist plains.' Franklin, p. 520.— The soil of the country about Hayes River nourishes a pretty thick forest, consisting chiefly of spruces, larches and poplars, but the trees are small, as the subsoil is perpetually frozen.' Ib. 499. On a farm in Llanvan parish in Wales two very lofty lime trees or linden are growing on limestone. The elm grows most luxuriantly in the red sandstone soil, without planting and without care.-The oak grows best in the stiff blue clay. The beech is best on the limestone brash.' Lance, Gold. F. p. 15. 34 Sir H. Davy's Analysis of Soils, p. 15. 35If there was ever a time, when the materials composing this globe, were XX. But one of the provisions most essential to all LETTER vegetation is, that wherever this is to appear, there should be always a due quantity of water, for the presence of this even gives fertility to a barren desert.36 A surprising quantity of devising care, and an adjusted deposition and arrangement of the rocks of the earth and water, could alone have produced that universality of vegetation, which delights us in every region of the earth. How this is so successfully and so permanently effected, I do not pretend to know or explain; but I see a wonderous system of skill and bounty in perpetual action to produce it; and all by exact, suited, definite, specific and impulsive yet limited agency. Clouds are made to form, collect, condense, move, and dissolve into rain, but always to send down only that quantity of water, annually,. which is wanted; not more, and not less. What would be injurious to man, animals and plants is carried off were collected into solid masses, such a condition must have excluded organic life. The formation of the soil has been apparently a work of time; and the result of the gradual attrition of the solid materials, composing the crust of the globe. Hence the formation of soil has probably, been always progressive, and is still going on. Besides this gradual attrition, the harder materials of our globe, seem to have suffered much disintegration, during the periodic convulsions formerly mentioned. By these, the different comminuted materials have been evidently mixed and scattered, and finally deposited over the surface of the whole earth, so as to give occasion to that infinite variety which every where prevails.' Dr. Prout, Bridg. Tr. 365. Capt. Burnes repeatedly found the fact verified in traversing the desert of Bockhara.—In the middle of the barren desert of the Oxus he came suddenly to the oasis of Kurshee which nature had thus made; here he found trees groaning with fruit, and some lofty poplars. Never were the blessings of water more apparent than in this spot, which must otherwise have been a barren waste. On the banks of the rivulet and its branches every thing is verdant and beautiful. Away from them, all is sandy and sterile.' Burne's Journ v. i. p. 263. XX. LETTER by rivers, or absorbed in the soil; yet enough is always on the surface to sustain vegetable life and health. Some kinds of earth, like sand, let it all pass thro them, without retaining any; others, as clay, will not let it permeate them, but detain it among them, which would be, if general, as pernicious as to retain none. Hence a most scientific disposition and arrangement has been made, and is maintained, as to the strata which form our cultivated soil, and the subsoils under it, that every where, just what is wanted in this respect is done and perpetuated, and what ought not to take place is prevented." By this skilful adjustment, the earth is ever clothed with that abundant supply and succession of herbage, grasses and trees, which, with unerring constancy, provides food and pleasure to all its sentient creatures that subsist upon it, altho their million numbers far exceed the powers of any comprehensible arithmetic to express. 38 37 Different vegetation prevails in different parts of the country. -In some parts of England the apple and pear are seen growing spontaneously in every hedge-row. In other parts, they will not flourish even with the utmost care. Some plants will flourish only on a calcareous soil, as a few of the orchis tribe in our country, and the teucrum montanum in Switzerland. Others will grow only in salt marshes, as the salzolas and the salicornias. Some flourish in sea water; some in fresh-to others, water is so prejudicial that they can exist no where unless on bare rocks or in arid deserts.-The larger number of plants prefer sunshine. Some are most vigorous in the shade, others are only found in absolute shade. There is not however a soil, however barren, nor a rock, however flinty, that has not its appropriate plant.' Dr. Prout, p. 366-8. 38 The latest discoveries in the vegetative process are ably stated by Dr. Lindley, in his Report on the Philosophy of Botany at Cambridge in 1831. From this I select the following facts: That plants have an ascending and a descending current of their sap or fluids. "That dicotyledonous plants increase by an addition to the circumference. That 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 |