box" with its contents is put on the centre of the stage, the little prisoner may be examined, sporting about in its native element. (Fig. 6.)

There are one or two special recommendations which the instrument we have been describing possesses, and which will commend it to all who are acquainted with what is requisite in a good instrument.

The stand is very firm and steady, so that there is no possibility of its overbalancing itself. The rack movement is smooth and easy, and the rack-bar is triangular. The screw at the bottom of the tube (for the reception of the object-glasses) is the "universal screw," so that any of the objectives made by the very best makers, and, indeed, everybody's object-glasses, will fit the instrument. The stage is constructed so as to receive either a condenser or polariscope apparatus, and the whole packs conveniently into a neat maho gany box which may be carried in the hand. So that, for its price, it is as excellent an instrument as any one could wish to place in the hands of a youth, and one that no one need be ashamed of using himself.

Hitherto our observations have been confined to the examination of objects of a transparent nature, with the light thrown through them; but there are many objects so opaque that they cannot be examined in this manner, but must have the light concentrated upon them by means of a "bull's-eye condenser." This is a separate piece of apparatus not included with the microscope above described, and may be purchased for about six or seven shillings. It is to be placed between the lamp and the microscope, and so adjusted

FIG. 7.

that the rays of light pass from the lamp through the lens, and are condensed upon the object, which by this means is brightly illuminated. The lamp should not be more than 6 or 8 in. from the lens of the condenser.

Any

lamp with a steady flame will answer the purpose. The best of cheap lamps is the common paraffin lamp at half a crown.

The next matter for serious consideration is the collection of objects; and this need cause no uneasiness, for objects may be found everywhere. The house and garden will furnish a supply for weeks, especially if during the summer and autumn months; and when home is exhausted, a short walk is certain to afford something.

No one who possesses a microscope should go out without a bottle or box in his pocket, to contain any object which may come in his way. A very useful bottle is figured, which costs about 1d. (Fig. 8, reduced.) By all means eschew stoppered bottles: corks are infinitely better, as well as cheaper. A

larger bottle will be required for dipping objects out of the water, with a wide mouth and a rim-what is called a "two-ounce" bottle-an India-rubber band, and a walking-stick. The India-rubber band will fasten the bottle to the end of the stick, and a collecting-bottle will be ready made. (Fig. 9.) If the bottle is fitted with a good cork, it may be carried home full of the results of the walk. Two or three small pill-boxes in the pocket are often found useful; but, above all, never forget the pocket-lens.

The structure of plants afford very interesting objects, almost without limit, such as the cuticle or outer layer of leaves. This may often be stripped from fresh leaves by the finger and thumb; but there are two more certain methods. One method consists in putting the leaves to be operated upon into a vessel of water, and allow them to remain until, in consequence of partial decomposition, the cuticle will separate itself from the leaf, or may be easily removed. By an occasional examination it will be readily determined when the soaking has been carried far enough. When such is the case, the cuticle may be floated off or removed with a camel-hair pencil. A fortnight is generally long enough for this operation.

A speedier method is to boil the leaves in a test-tube with diluted nitric acid for a few minutes; but we would commend the slower but equally certain process of maceration, especially to young people, acids being dangerous fluids to experiment with. The forms of cells in the cuticles of leaves are very variable, and any of the ordinary leaves of plants will furnish illustrations. They will also exhibit the stomata or orifices of the leaf surface.

The Lilac is a good leaf to exhibit these, the cuticle of under surface having a great many, and the upper surface but few. The cuticle of the under surface of the leaf of the Holly, and also of the common Laurel, should be obtained. A commonly cultivated exotic plant, called Yucca gloriosa, affords another form of cell and stomata. Some leaves are clad with very beautiful hairs, which can be removed with the cuticle. Of these, another cultivated foreign plant, Deutzia scabra, or its companion species, Deutzia gracilis, furnishes star-shaped hairs. Stalked hairs of this character abound on the woolly leaves of two or three species of Arabis common in gardens. (Fig. 10.) The mealy Guelder Rose and the Virginia Stock furnish also hairy cuticles. The cuticles of the petals (or floral leaves) of the Geranium and Pansy, and many other plants, form exceedingly beautiful objects

FIG. 10.

The cellular structure of the pith of the Elder, and even more beautiful star-like cells of the pith of the common Rush, afford examples of the cellular tissue of plants.

The spiral vessels may also be obtained from the stems of herbaceous plants, such as the Hogweed and Rhubarb. By maceration in water, the spiral strings may be drawn out easily. The maceration should be continued till the stems are quite soft. In some cases the spiral is simple, or composed of one single thread; in others several threads form a band. The leaf-cells of the common Bog-moss (Sphagnum) should not be forgotten, though of a different character. These require no maceration.

To transfer these delicate structures to the glass slide requires care. They should be first cleansed, under water, of all impurities, extraneous tissue wiped away with a camel-hair pencil, and, in the case of spiral tissue, two needles, with the heads inserted into wooden handles, may be used to separate the threads. The glass slide may be passed under the object as it lies in the water, and then gently raised out of the water with the cuticle or other tissue floated out smoothly upon it. The slides should first have the water drained from them by resting a minute or two on the edge or on one end, and then laid flat to dry. If the objects are to be examined at once, the glass cover may be placed over them as soon as removed from the water, and the object transferred to the microscope; but if the object is to be preserved for future examination, it must be mounted.

The process of mounting varies with different classes of objects, and the manipulation can only be perfected by experience.

The dissection of all objects requires a little help from a lens: if this is held in one hand, and only one hand left free, a great inconvenience will be encountered; but a simple contrivance to hold the pocket-lens will leave both hands free to use the nec

FIG. 11.

dles. If a penholder, or other rounded rod of wood, be inserted in a heavy block, and the pocket-lens be made to slide up and down on this, by passing

the rod through the hole in the handle of the lens, it may be so elevated or depressed that the object under the lens will be just in focus, and may be dissected with both hands at liberty. Some persons use a watchmaker's eyeglass for the purpose of dissection instead of à pocket-lens.

+

FIG. 12.

(Figs. 11, 12.)

Sections of wood and other hard portions of plants, although very instruc tive and beautiful when well done, are not to be recommended to the young amateur. It is hardly possible to cut good sections of wood without a sectioncutting machine, and there are hundreds of other good objects which entail no such trouble, so that we will leave all experiments in wood-cutting for the future.

There are many objects, both in the vegetable and animal kingdom, which may be mounted dry as opaque objects; and as this is the easiest method of mounting, we will describe how it is done. Pieces of wood, 3 in. long, I in. in width, and about in. in thickness, with a hole in the centre about in. in diameter, may be had for about one shilling per dozen (Fig. 13). Take one of these, and a piece of "dead black" paper I in. square, paste the black paper over the hole in the wood, with the black side to the wood. Turn the wooden slide over, and you have a cell in. in diameter, in. deep, with a black bottom. In this cell the object is to be mounted. For this purpose, gum tragacanth dissolved to a mucilage in water is preferable to gum arabic. The pollen of the Hollyhock, or small seeds, or little Beetles may be mounted by placing a little gum tragacanth mucilage on the centre of the black paper with a camelhair pencil. Lay the object upon the gum: it will adhere after gentle pressure, and must be left exposed till thoroughly dry. Cover the cell with thin glass a little larger in diameter than the cell: th squares will do well enough. A little Canada balsam or gold-size under each corner will secure it in its place.

We come now to an enumeration of a few such objects, of a vegetable origin, as may be mounted in cells, to be viewed as opaque objects with power of I in. Vegetable seeds are easily obtained in the autumn, and afford a great variety; as, for example, those of the Dandelion, surmounted by the feathery pappus by means of which they float about like parachutes; the seeds of the common Chickweed, of the Sweet William, and the Clove Pink. The seeds of the Poppy are also characteristic, and those of the Snapdragon, or Antirrhinum, the Mulleins, and of that favourite garden flower, the Eschscholtzia, must not be forgotten. To these may be added Coreopsis, the Larkspur, St. John's Wort, and the less-known Eccremocarpus, Sphoenogyne, and Paulownia imperialis. In fact, all small seeds should be examined, for we do not know yet, except in a few instances, what seeds are suitable and interesting objects. By all means we would strongly recommend the correct and explicit naming of all objects which may be mounted. Unnamed objects, or those named vaguely as "antennæ of gnat," "scales of butterfly," or "tongue of fly" are little better than rubbish. It is not difficult, in these days of scientific journals, to learn what species of gnat, butterfly, or fly affords the object, and then it possesses an interest and a value. Objects named only in the vague manner above indicated would prejudice the possessor in the estimation of any sensible

man.

Small portions of the leaves of many plants may also be mounted in ne cells, and will exhibit the hairs to advantage. Ferns also may have a fragment of the under surface of the fronds, showing the fructification, similarly treated. The pollen of the Hollyhock, Mallows, and many other plants; the capsules of Mosses, some kinds of mould and other fungi, should not be forgotten. Amongst animal life, small Spiders, Beetles, the Eggs of Butterflies, heads, wings, wing-cases, small shells, gall-insects, larvæ of various kinds, and all sorts of minute insects may be mounted in the same manner; indeed, all smali opaque objects of any kind, of which Nature is prolific everywhere.