vineyards are being washed away, the towns are threatened, the population is dwindling, and unless something is done the country will be reduced to a desert; until, when it has been released from the destructive presence of man, Nature reproduces a covering of vegetable soil, restores the vegetation, creates the forests anew, and once again fits these regions for the habitation of man.

In another part of France we have an illustration of the opposite process.

The region of the Landes, which fifty years ago was one of the poorest and most miserable in France, has now been made one of the most prosperous owing to the planting of Pines. The increased value is estimated at no less than 1,000,000,000 francs. Where there were fifty years ago only a few thousand poor and unhealthy shepherds whose flocks pastured on the scanty herbage, there are now sawmills, charcoal kilns, and turpentine works, interspersed with thriving villages and fertile agricultural lands.

In our own country, though woodlands are perhaps on the increase, true forest scenery is

Forests

gradually disappearing. This is, I suppose, unavoidable, but it is a matter of regret. have so many charms of their own. They give a delightful impression of space and of abundance.

The extravagance is sublime. Trees, as Jefferies says, "throw away handfuls of flower; and in the meadows the careless, spendthrift ways of grass and flower and all things are not to be expressed. Seeds by the hundred million float with absolute indifference on the air. The oak has a hundred thousand more leaves than necessary, and never hides a single acorn. Nothing utilitarian - everything on a scale of splendid waste. Such noble, broadcast, openarmed waste is delicious to behold. Never was there such a lying proverb as Enough is as good as a feast.' Give me the feast; give me squandered millions of seeds, luxurious carpets of petals, green mountains of oakleaves. The greater the waste the greater the enjoyment-the nearer the approach to real life."

6

It is of course impossible here to give any idea of the complexity of structure of our

forest trees. A slice across the stem of a tree shows many different tissues with more or less technical names, bark and cambium, medullary rays, pith, and more or less specialised tissue; air-vessels, punctate vessels, woody fibres, liber fibres, scalariform vessels, and other more or less specialised tissues.

Let us take a single leaf. The name is synonymous with anything very thin, so that we might well fancy that a leaf would consist of only one or two layers of cells. Far from it, the leaf is a highly complex structure. On the upper surface are a certain number of scattered hairs, while in the bud these are often numerous, long, silky, and serve to protect the young leaf, but the greater number fall off soon after the leaf expands. The hairs are seated on a layer of flattened cells the skin or epidermis. Below this are one or more layers of "palisade cells," the function. of which seems to be to regulate the quantity of light entering the leaf. Under these again is the "parenchyme," several layers of more or less rounded cells, leaving air spaces and passages between them. From place to place in

the parenchyme run "fibro-vascular bundles," forming a sort of skeleton to the leaf, and comprising air-vessels on the upper side, rayed or dotted vessels with woody fibre below, and vessels of various kinds. The under surface of the leaf is formed by another layer of flattened cells, supporting generally more or less hairs, and some of them specially modified so to leave minute openings or "stomata " leading into the air passages. These stomata are so small that there are millions on a single leaf, and on plants growing in dry countries, such as the Evergreen Oak Oleander, etc., they are sunk in pits, and further protected by tufts of hair.

The cells of the leaf again are themselves complex. They consist of a cell wall perforated by extremely minute orifices, of protoplasm, cell fluid, and numerous granules of "Chlorophyll," which give the leaf its green colour.

While these are, stated very briefly, the essential parts of a leaf, the details differ in every species, while in the same species and even in the same plant, the leaves present

minor differences according to the situation in which they grow.

Since, then, there is so much complex structure in a single leaf, what must it be in a whole plant? There is a giant seaweed (Macrocystis), which has been known to reach a length of 1000 feet, as also do some of the lianas of tropical forests. These, however, attain no great bulk, and the most gigantic specimens of the vegetable kingdom yet known are the Wellingtonia (Sequoia) gigantea, which grows to a height of 450 feet, and the Blue Gum (Eucalyptus) even to 480.

One is apt to look on animal structure as more delicate, and of a higher order, than that of plants. And so no doubt it is. Yet an animal, even man himself, will recover from a wound or an operation more rapidly and more perfectly than a tree.1

Trees again derive a special interest from the venerable age they attain. In some cases, no doubt, the age is more or less mythical, as, for instance, the Olive of Minerva at Athens, the Oaks mentioned by Pliny, "which were

1 Sir J. Paget, On the Pathology of Plants.