a rapidity which the temperate climates do not experience.* It can lie dormant without expiring in some species, when it seemed to have forsaken them.t This living principle has the singular property of remaining dormant and inert for years or ages, without therefore ceasing to exist. We all know that seeds may be kept a long while unsown, and yet grow whenever planted in a suited soil. This, again, is like animals who have been found enclosed in trees, and yet have revived. When plants are buried in the ground to a greater depth than is natural to them for their proper growth, they do not vegetate; but they do not therefore die: they retain their power of vegetation to an unlimited period; and when, by any accident, brought so near the surface as to suit their evolution, they begin immediately to grow. Ground that has not been disturbed for some hundred years, on being ploughed or turned up for any considerable depth, has frequently surprised the cultivator by the appearance of plants which he never sowed, and often which were then unknown to the country. This has arisen from ancient seeds becoming deeply covered, and there remaining inert, but yet retaining their principle of life. This principle has been ascertained to be capable of existing in this latent state for above two thousand years unextinguished, and springing again into * A Lapland and Siberian yew exhibits remarkably rapid vegetation beginning and fruiting in a single month; thus July 1.-Snow gone. 9.-Fields quite green. Aug. 2.-Fruit ripe. 18.-Snow. And from that time snow and ice to the 23d of June, when they begin Lo melt. †Thus mosses "Are extremely tenacious of life; and after being long dried, easily recover their health and vigour by moisture. Their beautiful structure cannot be too much admired."-Sir J. Smith, Intr. 493. "If the ground in old established botanic gardens be dug much deeper than ordinary, it frequently happens that species which have been long lost are recovered, from their seeds being latent in the soil."Ib, 94. A field that was thus ploughed up near Dunkeld, after a period of forty years' rest, yielded a considerable blade of black oats without sowing. It could have been only from the plough's bringing up to the surface seeds that had been formerly too deeply lodged for germination "— Loud. Encyc. Gard. 194. active vegetation as soon as planted in a congenial soil.* It even remains unimpaired in blighted corn, and will grow from that as vigorously as from the perfect seed. But yet, although thus abiding in vitality in its dormant state for an indefinite length of time, such is its delicacy of existence when once roused into its living action, that it perishes for ever if it be prevented from continuing its growth.‡ This living principle can subsist in all its reproductive power in fruit-trees from one to two centuries, and in others for many more. Some of the poisons affect the activity of this principle, though they do not destroy it.T But although we can observe these effects, we do not know what vegetable life really is. We can discern it to be something distinct and different from all the known. material agencies of nature. These can excite and affect and assist the agency, but cannot without it do what it does, nor be what it is. We are therefore authorized to deem it a peculiar sui generis principle, as distinct in plants from their material laws and substance as life and instinct are in animals. It is affectible or can be influenced by light, in its stem, leaf, and flower. It turns to this the upper surface of its leaves, and if they be forcibly turned from it they will At the Royal Institution in 1830, Mr. Houlton produced a bulbous root, which had been discovered in the hand of an Egyptian mummy, where it had remained above two thousand years. On exposure to the atmosphere it germinated, and when planted in earth it grew with great rapidity. Jour. Roy. Instit. No. 1. † Sir Joseph Banks, in 1805, sowed eighty grains of the most blighted wheat in pots, in a hot-house, and had seventy-two healthful plants. "Those who convey seeds from distant countries should be instructed to keep them dry; for if they receive any damp, sufficient to cause an attempt at vegetation, they then necessarily die, because the process, as they are situated, cannot go on."-Smith's Introd. 99. An apricot-tree one hundred and twenty years old, was bearing fruit sufficient for any family.-Life of L. Kames, vol. ii. p. 73. Pear-trees planted in the time of King William were, by gradual paring away the old wood and bark, covering the garden walls with new branches and fine fruit in 1807.-Smith, Intr. p. 29. A yew-tree was in existence at Peronne, in Picardy, in 1790, which was mentioned in the original charter for building the church in 634.Journ. of Science, No. 40, p. 412..... The most vital parts of the stem of a tree are thought to be the innermost layers of the bark, and the outermost layers of the wood.-Quart. Journ. Agric. Thus sensitive plants lose their power of contracting, if laurel water, opium, or nux vomica be applied. So they contract from cam phor, and do not dilate again.-Quart. Journ. Science, vol. ix. p 203. gradually revert back. Heat alone will not produce this effect. Many close their flowers, and others droop their leaves, when the light departs, as if to take their sleep;† and expand them in the morning, at various hours, according to their species. But this does not depend upon the sun; it is more like the roosting of fowls. Some flowers follow the path of the sun. The ripe ears of corn, in a whole field, will be found during the daylight to incline to the south, though they return to a different position at night. Warmth has a perceptible effect in raising the principle of life to its germinating and floral action. Hence a mild winter will cause it to anticipate its vernal efflorescence. Some plants also discover a peculiar susceptibility of atmospherical agencies, probably to electrical influences, which science has not yet elucidated. The motions of the moving plants are as yet not at all accounted for.¶ * Bonnet placed some plants in a heated stove; yet the stems did not incline to the side of the greatest heat, but to a small opening of the stove, from which some rays from the burning fluid issued......Sir J. Smith, in his lectures, stated, "It is an invariable circumstance, that plants always turi: their stem and leaves to the light, not towards the air. If in a hot-house, the door of which is left open, we shall yet always find them inclining to that side where the light is, let the air come in whence it may."-MS. Note. This may be seen in the daisy and the convolvulus. The leaflets of the mimosa fold themselves up along their common foot-stalk. Pliny and Theophrastus mention the lotus of the Euphrates as sinking below the water at night, to rise above it, and expand its blossom as the sun returns.-Smith, p. 333, 334. Flowers of plants removed from a hotter to a colder climate disclose their flowers at a later hour. Thus, that which opens in Senegal at six will not unfold in France and England till eight or nine, and in Sweden not till ten; and the flower that does not open in Africa till noon, or later, will not open in England at all. The convolvulus minor in our garden folded up its corolla in August at four in the afternoon, though the sun did not set till near eight. It opened in the morning gradually about two hours after the sun had risen. If the Siberian sowthistle shuts at night, the ensuing day will be fine if it opens, it will be cloudy and rainy. If the African marigold continues shut after seven in the morning, rain is at hand. The convolvulus arvensis, calendula fluvialis, and the anagallis arvensis, or poor man's weather-glass, close on the approach of rain.-L. Enc. 231. Mohl gives the anatomy of the sarmentaceous plants, and says, "Most of them turn to the left, and this direction is not owing to the action of light, or to the appui. This motion of the vrilles does not arise from spiral vessels, but from the irritability of their cellular tissue. In their revolving, the vrilles turn equally every way. But the stigma only move from below upwards, and always in one determinate way."→→→ Bull. Univ. 1830, p. 261 It is also one of the laws on which the vegetable organization has been constructed, that its living principle shall be separable from it, and shall depart from it, just as in man and brute. Here again specific ordainment visibly appears. Each has its appointed period of duration peculiar to its species, and dies when that has been reached. Thus, some are only annuals, and do not survive the year; others are biennials, or grow up in one year and die in the next; while others are perennials, or last for many years, reviving every spring. The changes which take place on the substance of the firmest tree, when its living principle has left it, attest the reality and power of this energetic agent, which, while it abides in its organization, resists and prevents such a material dissolution.* LETTER VII. The local Creation and gradual Diffusion of Plants-The fossil Traces and Remains of ancient Plants in the subterranean Strata-Their Indications of the primeval State and Vegetation of the Earth. WHEN the command was issued for the vegetable kingdom to arise, the whole of its numerous races either appeared simultaneously in every part of the globe, in immediate diffusion and completion; or they emerged on such particular portions only of the surface as sufficed for the production of every species; and from these primitive localities were disseminated gradually and successively over the rest of the earth. The sacred record does not decide or elucidate this point. It has preserved the man "When life is extinguished, nature hastens the decomposition. The surface of the tree is overrun with lichens and mosses, which attract and retain the moisture; the empty pores imbibe it; and putrefaction follows. The tribes of fungi which flourish on decaying wood then accelerate its corruption. Beetles and caterpillars take up their abode under the bark, and bore innumerable holes in the substance. Woodpeckers, in search of insects, pierce it more deeply, and excavate large -hollows, in which they place their nests. Frost, rain, and heat assist, till the whole mass crumbles away, and dissolves into a rich mould.”— Convers. on Botany, p. 365. date for their general creation, and declared its fulfilment, but has not described the manner or the extent of the first formation. Satisfied with asserting that all plants were the special and appointed creation of the same God who made the rest of our globe and the starry orbs which surround us, it leaves the chronology of every local vegetation to be investigated and ascertained by human inquiry and patient consideration. If we consult our historical and geographical communications on this subject, we find that the vegetation of many countries which have been examined, and of all newlyformed islands that have lately arisen, has been, and still continues to be, a progressive process; and we may trace it ourselves on many places near our domestic residence. We see the lichen class arise as their minute seeds descend; and decay and reappear from new germinal matter, till they have formed enough of vegetable substance for the sporules of the mosses, which at their seasons of fructification float extensively in the atmosphere, to fix on and to grow from. These mosses in like manner vegetate and decay, and on their decayed remains a new vegetation of the same sort springs up, in like manner to die and become a thicker mould for the passing seeds of other plants to find sufficient for their germination.* Every year thus produces a new bed of vegetable matter, which is frequented by the seeds of new plants, and, in time, of trees, as those various causes which we have in a preceding Letter enumerated bring them to the spot. Thus, in the course of a few years, every new coral island that is made by its petty architects, and every volcanic one that arises in the sea, become, in no long time, covered with plants and trees.‡ * This process may be noticed on roofs, and in part on palings. only the latter being perpendicular, the new seeds do not sufficiently fasten on them, but drop off to the ground. It may be seen more clearly on Inclined tiling; and partly on the common roofs. There, if the experiment be made, and be patiently watched for a few years, the progres sion will be distinctly seen. I have found mosses arise upon the decaying lichens, and new mosses, of a thicker foliage, grow upon the dead matter of the former ones; and the grasses afterward appear, as soon as the decayed remains had become a sufficient soil for their germination. † See before, p. 123-126.' See before, p. 123, Note[*].-M. Bennett, who has described his recent visit to several Polynesian islands, has thus noticed this process in |