a ee eee the albumen, completely enclosing it in the Wigella arvensis (Corn Cockle), Fig. 265; it is, on the contrary, surrounded on all sides in the seed of the Wood-Sorrel (Oxalis), Fig. 266.

Albumen is almost exclusively formed of cellular tissue. We observe in it neither fibres nor air vessels. These cells have sometimes thin walls, as in the Ricinus, Wheat, and other cereals; sometimes their walls are very strongly thickened, as may be seen in the horny and firm tissues of the Date-stone (Fig. 267), which is only the albumen of the seed. In the albumen of Wheat and other cereals, fecula predominates in the cells. The form of the starchy grains, varying with the species, is not unimportant. —

we add to this characteristic some other considerations taken from their size, and the structure of their grains, we might detect the adulteration of flour by a simple microscopic o servation, and at a mere glance.

The grains in Wheat (Fig. 268) are lenticular, elliptical, and egg-shaped. It is easy to distinguish these from the grains of the Potato (Fig. 269), which are generally larger, egg-shaped also, but with punctations, surrounded by certain zones, more or less regular and defined. In Maize (Fig. 270), the starchy granules of the horny part of the albumen are polyhedral, and nearly always show a punctation placed in their centre.

In the Oat-plant, the starch grains are of several sorts. Some are simple, and their form is oanioatig Fie. 267—Sec-egg-shaped, and fusiform. Some are formed of tw three, four, or a higher, but still limited number a elements. There are some, also, compound, either eens or egg-shaped; their diameter reaching about the five hundredth part of a millimetre, and their surface, under the microscope, resembling a mosaic of polyhedral segments. We find other substances besides starch in the 7% thin-walled cells of the albumen “& ge of theCastor Oil-plant,and in the “9¢%& thick-walled cells of the albumen of the Date. Oily matter abounds there. They are filled with corpuscles of a complex structure, Fig. 268.—Starch Grains of Wheat. whose chemical nature is not yet determined. These corpuscles, which in certain plants somewhat resemble grains of starch, may be termed mealy grains. They are more or less soluble in water, and are coloured yellow by iodine. Grains of starch are, on the contrary, insoluble in water, and are coloured blue by iodine. A very natural question here suggests itself as to the mode of transport and vitality of seeds; in short, as to the physiological phenomenon of germination.

Wind, running water, blocks of ice drifting in the Polar seas, the action of animals and men—that is, by cultivation—ships,

| merchandise, and voyages;

such are the causes, more or less powerful, which effect the conveyance of seeds from one , place to another. If we con- * sider how many seeds are light, hairy, and provided with a sort of wings in their downy tufts, we can understand that the wind may be the most general and ordinary meats for disseminating vegetable germs over acountry. Rivers also carry away the seeds of plants to great distances. If their course runs from north to south, or the contrary way, the wandering seeds would be carried to a climate where they could not live; but if the river flows from east to west, or from west to east, the seeds thus transported would much extend the limits of the species. The currents of the sea, which skirt the coast, or extend from one country to a neighbouring one, carry the

seed, so to speak, from one storing-place to another. In the latter case

the seeds remain but a short time 0 the water, and are little altered 0 consequence; besides, the graduated temperature of the successive localities which they reach is favourable to their acclimatisation and to their further development. The oper tion of blocks of ice in the transport of seeds is not without a certain importance. Navigators of the

Fig. 269.—Starch Grains of the Potato.

Polar seas often meet with icebergs loaded with an enormous mass of débris, mixed with earth and seeds. Seeds vegetate on these débris, and if the iceberg runs aground on some distant coast, where it melts, the seeds are deposited;they soon produce plants, which are then spread over the country by the other influences already hinted at. The dissemination of seeds is helped, it is said, by the distant migration of granivorous birds. Yet the influence of birds appear to us of very little importance in the matter we are now considering. Most birds completely destroy seeds in the act of digestion, and it is only exceptionally that seeds can traverse their intestinal canal without being destroyed.:

“Omniverous birds,” says De Candolle, “often search for berries containing little hard seeds, as Grapes, Figs, Raspberries, Strawberries, Asparagus, Mistletoe, &e. Their stomach is not so destructive as that of the gallinaceous birds, and it appears that small seeds can traverse their alimentary canal without alteration. When these birds are migratory, which is often the case in temperate and northern regions, they carry the seeds to a great distance, particularly when, in the autumn, they leave northern climates to seek the sunny south, for at this season ripe fruits abound in the country. Thrushes, many of which change their country either in Europe or in America, can thus transport some sorts. When they eat too large a quantity of stone fruit, they digest them badly, and spread the seed with the kernels. There is an observation of Linnwus which assures us that the lark scatters a great many seeds in the fields.”

By the same process, namely, by the imperfect digestion of seeds which have served them for nourishment, certain quadrupeds, particularly the herbivorous, are able to transport seeds from one part of the country toanother. This happens in the case of the reindeer, an animal living in herds in the plains of Siberia, which, at a certain period, migrate in large numbers. Such also is the part played by the herds of cattle driven often to great distances in our European climates, and in general in all civilised countries.

The action of men in the dissemination of vegetable seeds is shown in a thousand ways. We will borrow from M. Alphonse de Candolle some interesting remarks on this subject. —

“The first colonies which were sprinkled over each continent,” says this learned botanist, “probably carried with them several species of useful plants, and especially some of those seeds which get attached to clothes and to domestic animals, and which will grow easily in the neighbourhood of dwellings, near dung hills, burnt ground, and rubbish heaps. The scantier the population, and the more foreign it is to the arts of civilisation, the more insignificant become these primary seed-carryings. When the population becomes denser and more civilised, when agriculture begins and extends its rule, then the occasions are multiplied for the transport of seeds. A hunting or pastoral people, no doubt, traverse a vast extent of country, but an agricultural people prepare ground fit for the reception of new species, and bring the seed for their

fields from more or less distant countries, introducing with it different plants, many of which naturally grow wild. In short, war has created vast empires, and compelled men to make numerous journeys; navigation has extended itself, new countries have been brought in communication with the old, agriculture has exported its products, and horticulture has stocked our gardens with thousands of foreign species. By all these means the transport of seeds has become increasingly great, and an influence has been exercised quite preponderating over natural causes.”

Commerce, which carries in its ships the products of the trading of nations, furnishing Europe with the produce of the New World and returning to it European productions in exchange, is sometimes an indirect agent in the transport of vegetable seeds. The wool from the sheep of Buenos Ayres, Mexico, or La Plata, when it is brought into Europe, carries entangled in the fleeces the seed and remnants of plants in those countries. When the fleeces arrive in Europe, they are cleaned, beaten, and washed, and the seeds fall off; they may then shoot in this new soil, and transplant into our climate the vegetable species from regions across the Atlantic. At the edge of the river Lez, near Montpellier, at 4 place called Port Juvenal, the American wools are received to cleaned and purified, and then sold to the cloth-makers of Lodéve. Seeds of American plants, which have been brought in these fleeces, have actually sprung up in the environs of Montpellier, 8° much so that all the celebrated botanists of Montpellier, such as

De Candolle, Dunal, Delille, Gordon, and Ch. Martins, have examined and studied in this small place in southern France many vegetable species belonging to the Flora of Buenos Ayres and Mexico. How long does the power of germination last in a seed? Some seeds rapidly lose their latent life, or, which comes to the same thing, the faculty of germination. There are others which, placed in the same‘circumstances, preserve their vitality for ages.

The seeds of most plants of the Leguminous tribe will germinate many years after they are gathered. Every one has heard that the seeds of Beans, taken lately from the herbal collection of Tournefort, a celebrated botanist in the seventeenth century, germinated perfectly. In 1824 there were sown, at the Jardin des Plantes of Paris, some seeds of the Mimosa pudica which had been gathered at St. Domingo in 1738.

If seeds are placed under special conditions, sheltered from atmospheric agency, in ground more or less dry and heaped up, for example, in tombs or catacombs, their vitality maybe preserved for a prodigious time. It is a recognised fact that, after the destruction of a forest, we see a new sort of growth appear on the ground the forest used to occupy. It has been admitted, to explain this fact, that seeds of trees, buried in the ground while the forest existed, were preserved in the soil, with their life suspended during a considerable number of years; that, then awaking from their lethargic sleep, they have been developed under the influence of new conditions favourable to their germination. This hypothesis 1s plausible enough in some cases, yet as no scientific experiment has been made on the subject, it might happen that in this case the second germination of trees was owing to the transport of foreign seeds, which germinated as soon as the soil had become free, and restored to light. ost marvellous examples are quoted of the longevity of seeds. Dr. Lindley, the learned botanist, asserts that some Raspberry seeds which were found in a Celtic tomb, and which numbered about seventeen hundred years of existence, had germinated perfectly, and produced Raspberry plants, which still exist in the Horticultural Society’s Gardens in London. M. Ch. Desmoulins asserts that the seeds of the Lucerne, Cornflower, and Heliotrope

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