The Vegetable World: Being a History of Plants, with Their Botanical Descriptions and Peculiar Properties

takes place, with the matter of the fungus. It is a mucous, gelatinous, and perfectly colourless substance, which separates little

Fig. 327,—Fireblast, or Smut, on t € Fig. 328.—Section of a Maize Ovary Maize plant. attacked by Smut. by little into small polyhedral rounded masses, which by re-clothing themselves, sometimes according to a tegumentary system, ome spores.” The Vinx Funavs, which is the Oidiwm Tucheri of Berkeley, is Supposed also to be a state of Erysiphes—a genera of small fungi Which the world has a great interest in being acguainted with.

The elegant structure and varied form of some of these minute upon them, longei had fixed the attention of mycologists i the unforeseen result of M. Tulasne’s investigations became : own. These microscopic plants possess, according to M. Tulasne, 0 less than three kinds of reproductive apparatus, which make to the and the fungus destructive ir appearance successively,

vine is only another species of Erysiphes, which forms the two first evolutions only of the reproductive organs:

The organs of vegetation in the Erysiphes consist of a mycelium formed of fine thread-like filaments, furnished with spores the form and functions of which remind us in many respects of ‘the suckers of the Dodder-plant; which leads to the inference that in these fungi we see parasites which live upon the green or living parts of vegetables, particularly upon the leaves. Certain filaments of the mycelium bear straight branches more or less numerous, which swell at the extremities into ellipsoidal utricles, and eon-stitute small organs, often in the form of a chaplet of beads, formed

Fig. 329.—Reproductive Organs of Eresyphus (Conidia).

to the fugitive buds of ee cells, analogous of reproductive plants. To this first reproductive system M. Tulasne gives a ee. aename of Conidies (Fig. 329).

Another class of organs consists of spherical or ovoid vesicl® small ~ a innumerable and filled withgenerally pedicellate, in Fig. oe" represented This second system,oblong corpuscles. oS ahe calls Pycnides. reproductive organs which constitutemat Such are the two sorts of the Oidium. Tuckeri of Berkeley;which is, however, only n°" the Erysiphes, the last and perfect form of which has not yet — aloped itself.

This, the latest and most important form, consists in globulous conceptacles, sessile, at first colourless, then yellowish brown, and finally black and more or less spotted, which bear, like the

Fig. 330.—Reproductive Organs of Erisyphus (Pycnides).

two first sets of organs, certain filaments of the mycelium. They are all accompanied at maturity with a variable number of filiform appendages, whose form, dimensions, and position vary with the

Fig. 331.—Third kind of Reproductive Organ of Erisyphus (Conceptacies).

Spores under consideration (Fig. 331). They are simple or branching, and frequently terminate in arms divided into pairs. In the bosom of the conceptacles are found sacs or theca, variable also in number, generally ovoid, attached by a short claw to the base of the conceptacle. The number of spores, which are constant to each species, vary from two to eight. The conceptacles open “regularly in order to permit the theca or sporesto issue.

The Movtps were long supposed to have a very simple organisation, because they had been imperfectly observed. Even in our days they are very imperfectly known. It is now known, however, that some of them are endowed with multiplied reproductive apparata. The Mucors, which are the commonest of the Moulds, - grow on organic substances in a state of decomposition, forming large catonous tufts, with vesicles full of greenish spores on the summit of long slender pedicels (Fig. 332). It has only recently been:ascertained that the genera which had been -named respectively Aspergillus and Eurotium are only two different and successive modes of fructification; Aspergillus being the — fructificationof the young, Eurotium that of the

Fig. 332.—Mosses. adult state.

The parasite which proved so destructive to the potato belongs to the family of fungi now under consideration; and here also we note two modes of fructification; one, namely, in which the spores are born naked at the extremity of the filaments, while in the other the spores are contained in certain voluminous vesicles. In a recent memoir, M. de Bary, professor in the University of Fribourg in the Brisgau, has directed attention to the very curious phenomena attending the germination of the naked spores, and ag may be useful to present a resumé of these interesting researches.

The spores, or rather the so-called naked spores of the potato parasite, of the Peronospera, present us with three distinct modes of germination. In the first process germination is indicated by the emission of simple or ramified filaments, which possess the power of penetrating the tissues of the potato by piercing the walls of its superficial cells. The second form of germination 18 characterised by the formation of a secondary spore, from the summit of ‘which issues a simple tube, which in due course attains the length of two or three times its greatest diameter, expanding like a vesicle at the extremity. When all the plastic contents of the spore are enclosed in this terminal vesicle, it is isolated from the a distinct cell. germ by a partition, and thus constitutesJilamentous But this spore of the second order is a phenomenon of rare occur rence, and of secondary importance only, according to M. de Bary:

In the third mode of germination the spores (Fig. 833, A) divide themselves into a certain number of polyhedric portions (Fig. 333, 8), which ina short time begin to issue, one after the

B c

Fig. 833,—Germination of the Spores in the Potato.

other, by a round opening (c), thus constituting egg-shape zoo- Spores furnished with two unequal cilia; the shorter of those most forward, in advance of the corpuscle, and the other dragging after it (Fig. 333, p). The movement of these small bodies lasts for about half an hour, describing a circle, which gets slower and slower until it enters a state of perfect repose. Now that it has become immovable, the zoospore takes a regularly rounded form, Siying birth on one side to a germ-tube, slender and curved, whicl lengthens itself rapidly in water.

If the zoospores are sown upon the nurse plant, and other circumstances are favourable, the zoospores attach themselves te the epidermis of its fragments, giving out their usual germ, Which after climbing a short time on the outside begins to enter 4 epidermic cells. Their extremities thus attached soon acquire a Considerable thickness, which afterwards increases in a tabular form, which perfectly resembles the filaments of the adult mycelium y -~ and it soon insinuates itself into the depth of Peronospera, the tissues of the hospital plant.

Tue LicHens. ites or Liverworts are cellular plants, requiring free access light and air, and of simplest structure. They form irregular Patches, more or less dry, according to their exposure upon the Surface of stones, trees, and other bodies which they cover, while

decorating them with a thousand varied hues of colour. These — Thallogens live in the air, never in water. Their existence may endure for hundreds of years; their growth and propagation are both excessively slow. They are found in all regions of the globe, from the tropics up to the poles. They grow on the summit of the loftiest mountains, in the plains and valleys, and at all intermediate heights. Near the limits of eternal snow, where all other signs of vegetation have disappeared, on the edge of glaciers, and up to the 70th degree of north latitude, that is to say, at the nearest point to the Pole which has been approached by ma, the Lichens still vegetate. Humboldt and Boussingault found them growing near the summit of Chimborazo, and they are the last vegetables which are found on the slopes of Mont Blane.

In form these universally disseminated plants are cellular and flowerless, formed of a lobed and foli called a thallus, which is formed of a cortical, and medullary layer—the former being cellular, the latter both cellular and filamentous. Others are crustaceous, when the cortical is coloured and the medullary layer is colourless. The reproductive matter is of two kinds:— 1. Spores, naked, or lying in membranous amylaceous tubes “oF thecze immersed in nuclei of the medullary substance, which through the cortical layer and colour, and harden by exposure " the air in the form of little discs, called shields. 2. The separated _cellules of the medullary layer of the thallus. These, call gonidia, are of a green colour, and lie singly or in clusters beneath the cortical layer of the thallus, and break out in clusters called soridia, or in cups called cyphelia.

Although Lichens, with one or two exceptions, are a a immersed in water, they are said in all cases to be developed 4 humidity, resembling in that state Phycew and Conferve; as soon as the humidity diminishes, the under part dies inert leprous crust is formed, which becomes the basis 3 forming plant. Hence the two sorts of tissues—living cellule the vegetating part, and dead cellules which have lost thet cohesion; the latter have their reproductive powers while every part of the living stratum has been ascertained to possess TePr” ductive properties.. os Some Lichens are employed in medicine, others are subjects

domestic economy, some in the art of painting. The Iceland Lichen (Cetraria Islandica), Fig. 334, is demulcent, and is em-

Fig. 334.—Cetraria Islandica.

ployed in many affections of the chest; the great quantity of fecula which it contains renders it esculent. Sticta pulmonaria

Pulmonaria. Fig. 335.—Sticta (the Lung-wort lichen), Fig. 835, is in Siberia a substitute for rangiferina is an of beer. Cladonia preparation © hop in the ot substitute for pasture to the reindeer, whose instinct y vers it even under the snow.

The Orchil or Archil is a valuable die, and Lecidea Tartarea is the cudbear of commerce, which is imported to the value of £80,000 annually. One of the most curious of this family of Thallogens is Lecanora — esculenta, a lichen which is frequently met with in the mountaims of the arid deserts of Tartary. It is found in great abundance m the Kirguis deserts to the south of the river Jaik. It seems t fall from the sky as a sort of miraculous manna. Men and beasts are nourished on it. But what is really remarkable is that it occurs in the form of -small globules, whose size may vary from the head of a pin to a hazel-nut. They are invariably free, being attached to no other body. It follows from all this that the Lichen while the = and increased itself rapidly;has vegetated develops transported it from one place to another. The light mass whic constitutes these Lichens are, in short, often transported by the the Israelites supported which The manna air to greatdistances.