attraction which partly destroys the effect of gravitation, and determines the ascent of the liquid to a much higher level than it would attain in a larger tube. The phenomenon of capillarity is, then, added to the action of endosmose to favour the absorption of liquids by the radicular extremities. en the plant is furnished with leaves, there is a third force which unites with the two others in accelerating the absorption. The leaves are the seat of a considerable evaporation. The water dispersed into the atmosphere in the form of vapour leaves a partial vacuum in the vessels; this vacuum is immediately supplied by the afflux of the liquids flowing from the roots. In this manner leaf action is produced; this is a sort of suction which draws towards the leaves an afflux of liquid, which the radicular absorption is constantly compelled to supply.

Thus endosmose, capillarity, and suction, in the upper part of the plant, are the physical forces which appear to play a part in the absorption carried on by roots. We must, besides, in order to explain the great phenomenon of the life of plants, bring in a foree very superior to all these physical actions. This is the action of vital force, that secret and invincible power which God only bestows and of which He alone directs the results.

II.—Tue Srem or Puanrts.

The stem is the axis of the ascending system of the vegetable. It is furnished at intervals with vital nodes, or eyes, from which spring the leaves, buds, and branches, arranged in a_ perfectly regular order. The root presents nothing of a similar nature. This characteristic enables us easily to distinguish in the vegetable axis between that which belongs to the stem, and that which is peculiar to the root. The stem is that part of the plant which, rising into the air, produces and supports the branches, boughs, leaves, and flowers. Through its tissues the liquids inhaled by the roots penetrate into the interior of the vegetable for the purpose of supplying it with nourishing juices, increasing its growth and maintaining its vital functions. , The form, size, and direction of the stem depend on the part

which each plant has to take in the vast vegetable population which covers and adorns the globe. Plants which require to live ina pure and often renewed air, have a straight stem, either robust or slender, according to their individual habit. Where they require a moist and denser atmosphere, when they have to creep along the ground or to glide among the brambles, the stems are usually : long, flexible, and trailing. If they have to float in the air, supporting themselves on plants of more robust growth, or to hang suspended from forest trees in graceful festoons and light garlands, they are provided with flexible, slender, and pliant stems, which enable them to embrace with their tendrils the trunks of trees or shrubs. Thus, nature fashions the outward forms of plants according to the part which they are intended to fill, and ac- _ cording to the functions which have been allotted to them. Nothing is more variable than the appearance of the stem in vege- \ tables and trees; in their infinite *&\ variety they sometimes present ’ to us perfect types of beauty and elegance. Sculpture and painting have borrowed from the trunks of certain trees, models of Fig, 22,—Bindweed. architecture at once elegant and majestic; types which have been handed down to us from the most remote antiquity, and which are still the models in use. Man has discovered in vegetable forms his first designs for adornment, construction, and. The stem of the Palm-tree and the Date-tree, and the leaves of the Acanthus, formed a model for the majestic columns of the Corinthian order; the leaves of the vine and the natural garlands of young climbing

plants furnished ancient art with types of ornamental design, which are still preserved in modern architecture. kig. 23.—Trunk of an Oak. In botanical language, the stems of plants are not always called by the same name. The stems of trees, as the Oak (Quercus)

THE VEGETABLE WORLD.

Fig. 24.—Culm of the Rye.

in our climate (Fig. 23), bear

the name of trunk. The

stems of the Gramine (grass

family), commonly cylindrical,

and nearly always indented by

annular knots from which the

leaves spring, ‘are called the

culm (Fig. 24) ; those of Palm-trees, which resemble columns

crowned with a chaplet of leaves,

are called stipes (Fig 25)—terms,

however, which botanists rarely

employ.

The thickness and height of

stems vary very much among

vegetables. Whilst the trunk of

certain exotic trees, as the monstrous Baobab, attains gigantic

dimensions, the stems of many of

our spring plants, as those of the

Sassifrage, and the Early Whit-

\ low grass (Drabaverna), scarcely

{

attain the thickness of a thread.

‘‘ While crossing the Rio Claro,

a river in the province of Goyas,

in Brazil,” says A. de Saint

Hilaire, “I perceived growing

on a rock a plant not more than

three lines in size, which I took

at first for a moss. It was,

however, a species of a superior

order, and provided with a reproductive apparatus like our

oaks and beeches. By the side

of it gigantic trees reared their

majestic heads to the height of

a hundred feet.”’

Accordingly as stems last one

year, two years, or more, they are called annual, biennial, or perennial. Aborescent stems which live a greater or less number

Fig. 25.—Stipe of the Palm-tree. of years, and form solid wood, are “said to be ligneous, or woody. The soft stems of annual, biennial, or perennial plants are called

herbaceous; and the stems of the leek, the cactus, and some of the euphorbias, are called succulent. Fig. 26 represents the stem of a cactus in flower. In a great number of plants the stem rises firm and straight into the air. It is then called an upright stem. There are some, on the contrary, which have not consistence enough to keep themselves upright; they stretch along the ground, only lifting up their heads, so to speak; these are procumbent stems; or, being quite prostrate, they are fixed by adventitious roots or sunken, and are called creeping stems.:

Fig. 27 represents the procumbent stem of the Veronica

Fig. 26.—Stem and Flowers of a Cactus.

officinalis. Others, like the ivy, hang on to neighbouring bodies by the aid of their suckers or adventitious roots; or, like the bindweed, they entwine themselves spirally round trees. The first are called scandent stems, the latter volubile. olubile stems do not all*twine in the same manner; but the direction of twining of stems is invariable in the same species, and

Bindweedeven resists efforts made to change it. Some, like the (Fig. 22), if we suppose that they are twining round our own body, go from right to left; Beka: as the Hop (Fig. 28), go from left to right. ‘The Lianas, which in the primitive forests produce the most marked varied results,” says A. de Saint Hilaire, “and which impart to these cease their most picturesque beauties, are ligneous plants, some of them scandent, others volubile. These are the Bibouia Bauhinia, Cissus, &c., and though they all need a support, yet each plant has a bearing which is peculiar to itself. Some lianas resemble wavy ribbons; others are twisted, and describe large spirals. They hang in festoons, wind about among the trees, leap from one tree to another, and entangling themselves. together, forming masses of leaves and flowers, so that the observer finds it difficult to distinguish to which tree it belongs.”

These Lianas of the American forests, are very imperfectly represented in our climate by the Ivy, the Honeysuckle and the Clematis, the Bindweed, and the Hop-plant. The stems of ‘which we have spoken are aerial; but there are subter-

Fig. 27.—Procumbent Stem of Veronica officinalis.

ranean stems. The Solomon’s Seal (Fig. 29) presents a subterranean stem, thick, fleshy, whitish, and indented on its upper surface with scars corresponding with the bases of old aerial stems (thence the name of seal which this plant has preserved). This subterranean stem terminates at its foremost extremity with a leafy and flower-bearing axis, placed behind a terminal bud, which will develop itself the following year. Many plants, as the iris, flowering rush, water trefoil, and carex, alike present subterranean roots. Fig. 30 represents the subterranean root of the Iris germanica. These roots have received from botanists the name of rhizomes, from ῥίζωμα, a root or root stock. They creep obliquely or horizontally under the surface of the soil, and vegetate at their most advanced point, whilst the hinder part is gradually destroyed by age. This mode of existence in subterranean roots is well exemplified in Fig. 31, which represents the growth of a sprig of Carez, 80 called from careo, “to want,” its upper spikes being seedless. In this engraving is shown the horizontal and creeping axis, which represents at once scales or modified leaves and root-fibres, and -which sends out leafy shoots at intervals. The shoot 1 is only one year old,—in the next spring it will assume the form of the shoot 2; the following year it will bear flowers and fruit, as in 3; the production of fruit will mark the term of its existence, as shown in 4. Fig. 32 is the Maize plant (Zea Mays). Another very remarkable kind of subterranean root is that which forms the central or essential part of udbous plants. ‘Cut

Fig. 28.—The Hop-plant.

the bulb of a hyacinth or lily longitudinally; it will be observed: that it is composed of a fleshy surface, more or less conical in the upper part, and truncated below, constituting a short stem, with internodes or knots placed very close together. This surface gives rise, at its upper face, to fleshy scales, which are modified leaves pressing one against the other, and to a central bud formed of leaves and rudimentary flowers, whilst from its lower face spring the root-fibres. In the Hyacinth (Figs. 33 and 34) the scales form

Fig. 29.—Solomon’s Seal.

complete sheaths, which grow one over and round the other, and its bulb is tunicated. In the Lily (Figs, 35 and 36), the scales are smaller, and overlap one another like the tiles on a roof of a house; its bulb is scaly. In the Crocus (Figs. 37 and 38) the base of the stem is extremely broad, of a globular or depressed shape, and only produces a few thin and membranous scales; its bulb is said to be solid and superposed, several stems rising out of its upper surface. The rhizome and the dulb are only distinguished from each

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