repression only causes it in the regions of frost and snow to spring up, as soon as the brief season of heat occurs, with a rapidity which the temperate climates do not experience(52) It can lie dormant without expiring, in some species, when it seemed to have forsaken them.(53)

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 inclosed 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.(54) 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 ne

By steeping the seed in the chlorine gas, the process was hastened: cress seed then began its germination in 32 hours.—Achard found that they would not grow in heterogeneous hydrogen gas. Loud. Enc. 195.

(52) 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.
17.-Plants at full growth.
25.-Ditto in flower.

Aug. 2.-Fruit ripe.

18-Snow.

And from that time snow and ice to the 23d June, when they begin to melt.

66

(53) Thus mosses are extremely tenacious of life; and after being long dried, easily recover their health and vigor by moisture. Their beautiful structure cannot be too much admired." Sir. J. Smith, Intr. 493.

(54) "If the ground in old established botanic gardens be dug much deeper than ordinary, frequently happens, that species which have been long lost are recovered, from their seeds being latent in the soil.” Ib. 94.

ver sowed,(55) 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 active vegetation as soon as planted in a congenial soil.(56) It even remains unimpaired in blighted corn, and will grow from that as vigorously as from the perfect seed.(57) 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 forever if it be prevented from continuing its growth.(58)

This living principle can subsist in all its reproductive power in fruit-trees, from one to two centuries, (59) and in others for many more.(60) Some of the poisons affect the activity of the principle, though they do not destroy it.(61)

But although we can observe these effects, we do not know what vegetable life really is. We can discern it to be

(55) "A field that was thus ploughed up near Dunkeld, after a period of 40 years rest, yielded a considerable blade of black oaks, without sowing. It could have been only from the plough's bringing up to the surface seeds that had been formerly been too deeply lodged for germination." Loud. Encyc. Gard. 194.

(56) 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 2,000 years. On exposure to the atmosphere it germinated, and when planted in earth, it grew with great rapidity. Journ. Roy. Instit. No. 1.

(57) Sir Joseph Banks, in 1805, sowed 80 grains of the most blighted wheat in pots, in a hot-house, and had 72 healthful plants.

(58) "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.

(59) An apricot-tree, 120 years old, was bearing fruit sufficient for any family. Life of L. Kames, v. 2, 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.

(60) 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.

(61) Thus sensitive plants lose their power of contracting, if laurelwater, opium, or nux vomica be applied. So they contract from camphor, and do not dilate again. Quart. Journ. Science, v. 9. p. 203.

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 affectable, 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 gradually revert back. Heat alone will not produce this effect.(62) Many close their flowers and others droop their leaves when the light departs, as if to take their sleep ;(63) and expand them in the morning, at various hours, according to their species.(64) But this does not depend upon the sun : it is more like the roosting of fowls.(65) 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

(62) 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 turn their stem and leaves to the light, not towards the air. If in a hothouse, 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.

(63) 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. 333-4.

(64) 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.

(65) 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,

yet elucidated.(66) The motions of the moving plants are as yet not at all accounted for.(67)

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 perennial or last for many years, reviving every spring. The changes which takes 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.(68)

(66) 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 spproach of rain. L. Enc. 231.

(67) 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.

(68) "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 mold." Convers. on Botany, p. 365.

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 mandate for their general creation, and declared its fulfillment, 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 newly formed 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 fructifica