comprise the largest number of species, and will pass on to the divisions of dicotyledonous plants.

Here we must characterize the four sub-classes into which this class is divided, and bravely encounter four more long names. The first is called Thalamifloral exogens, the second Calycifloral exogens, the third Monopetalous exogens, and the fourth Monochlamydous exogens. If we endeavour to ascertain the meaning of these, although they will not become shorter, they will seem to be less hard to remember.

If we were to call the Thalamifloral "disc-flowered," the Calycifloral "calyx-flowered," the Monopetalous "one-petalled," and the Monochlamydous "one-covered," we should have names apparently less pedantic, but we would not by that means come much nearer to their meaning. In the first sub-class of exogens the petals of the corolla are distinct from each other and from the calyx or outer circle of floral leaves. The stamens are said to be hypogynous, that is, the bases of the filaments are so attached that they seem to spring from underneath the ovary or basal portion of the pistil. The woodcut may serve to render these distinctions more comprehensible. (Fig. 51.) It is a section cut down a thalamifloral flower. represents the petals, c the calyx, s the stamens, and o the ovary at the base of the pistil.

Calycifloral exogens are those in which the petals are also usually distinct, but the stamens, instead of being hypogynous (as in the above), are either perigynous or epigynous. Now, by "perigynous" it is meant that the stamens stand around the pistil, but that the bases of the filaments do not originate from beneath the ovary. By "epigynous" is meant that the bases of the filaments of the stamens spring from or are seated upon the ovary. Thus a similar section of a calycifloral flower has the structure indicated in Fig. 52. The letters refer to the same organs as in Fig. 51.

It will be observed that in both these sub-classes the petals are separate and distinct one from the other. In a few instances they are absent.

In the sub-class of Monopetals the petals are united, either at the base or all together into one piece or corolla. (See Figs. 30 and 53.)

In the last sub-class, or Monochlamyds, the perianth is really or apparently simple; that is, there only seems to be one circle of floral envelopes instead of two, the calyx or corolla being absent, and sometimes both.

If we endeavour to place the features of these four sub-classes in a clearer light, by eschewing all we can of the technicalities, we should say that in two of the four groups the outer and inner leaves of the flower are generally present, and that the inner leaves are not joined to each other, but may be plucked off separately. We may add that the chief distinction between the two groups is the manner in which the stamens are attached. In the first group their bases are attached under the ovary, and in the second around or upon the Ovary.

In the other two groups one has both kinds of floral leaves or envelopes, and the other has but one or none. In the group possessing both calyx, or outer circle, and cor.lla, or inner circle, of floral leaves, the inner circle or corolla has the leaves joined together at the base, or form a kind of tube. Bearing these distinctions in mind, we shall examine each group separately through its subdivisions.

into

The thalamiflorals are divided, according to the structure of the ovary, two sections. In the smallest section the ovary is said to be apocarpous, and in the other section syncarpous. By an "apocarpous" ovary is meant an ovary

in which each carpel, or modified leaf of which the ovary is composed, remains distinct; and by a "syncarpous" ovary, one in which all the carpels are united into one compound ovary. Thus a buttercup has an apocarpous ovary, which looks like a cluster of ovaries, because each carpel is distinct. This is seen better in the fruit, from its larger size, of which we give a figure. (Fig. 54.) The poppy has a syncarpous ovary, all the carpels being united into one compound ovary. The structure is the same in the fruit, which is a larger and mature state of the ovary, so that we figure the fruit in preference to the ovary. Each of these sections of thalamiflorals contains several natural orders; as, for instance, the first section, in which the ovary is apocarpous, includes the

Ranunculacea or ranunculus family, the Berberidacea or berberry family, and the Nympheaceae or water-lily family. Each natural order includes several genera-often a great many, sometimes only one or two. The Ranunculacea include a great many different genera, but all of them have a certain number of petals to their flowers, with a large and indefinite number of stamens. This is true of the buttercup, it is true of the anemone, of the aconite, of the meadow-rue, and of the columbine; yet all these plants differ so much in other features that they belong to different genera. The genus Ranunculus includes all the species of buttercup or crowfoot, and from this genus the whole order derives its name. The common meadow crowfoot or buttercup (Ranunculus acris) belongs to the natural order Ranunculacea, and the apocarpous section of thalamifloral exogens. It belongs to exogens because of the net-veined leaves and twin cotyledons or seed-leaves; to thalamiflorals, because the petals are distinct, and the stamens spring from under the ovary; to the apocarpous section, because the carpels in the ovary are separate; to the natural order Ranunculacea, because of the definite number of petals and the indefinite number of stamens; and to the genus Ranunculus, because the one

seeded carpels form a globose head, and the petals have a scale or hollow thickened spot at the base.

The section of thalamiflorals with syncarpous ovaries contains a great many natural orders, so that these are generally divided into two sub-sections according to the internal structure of the ovary, which must consequently be cut across with a sharp pen-knife and examined with a pocket-lens (see "The Microscope," Fig. 11), which can be purchased for 15. or 1s. 6d. If we cut across the ovary of a poppy, and then look at the section through a lens, we shall observe that the ovules are clustered upon little projections from the inner surface of the walls of the ovary. These projections are termed placenta, and represent the edges of the united carpels. When the placentæ project from the inner surface of the walls of the ovary, but do not reach to the centre, the ovary contains but one cell or cavity, and the placenta are called parietal, or projections of the wall (Fig. 57). But if the placentæ extend to the centre, and bear the ovules at the centre (Fig. 55), dividing the ovary into cells or compartments, or if the ovules are borne around a central column, the ovules are said to be axile (Fig. 56), as in the pink family. The first sub-section contains the poppy family, or natural order Papaveracea, the crossworts, with four petals, as the turnip, cabbage, mustard and cress, &c., which belong to the natural order Crucifera, the mignonette family, the violet family, and some others. The second sub-section includes the pink family or natural order Caryophyllacea, the mallow family or Malvacea, the geranium family or Geraniacea, and some others.

The Calyciflorals differ from the thalamiflorals in the manner in which the stamens are inserted. In the present sub-class the stamens are either placed around or upon the ovary. Taking advantage of these two modes, we may recognize one section of calyciflorals in which the stamens are perigynous, or placed around the ovary, and another in which the stamens are epigynous, or placed upon the ovary.

The first section includes about a dozen natural orders represented in Britain. the second contains only four or five.

The most prominent orders in the first section are the pea-flower family, or Papilionaceae (this is, in fact, only a portion of the order Leguminosa, the remaining tribes of the order not being represented in Britain). The flowers are irregular, of the papilionaceous type, that is, they are supposed to resemble a papilio or butterfly at rest (Fig. 58). Then there is the order Rosacea, with regular flowers and a great number of stamens, as in the rose, blackberry, strawberry, pear, apple, hawthorn, &c.; the gourd or cucumber family (natural order Cucurbitacea); climbing plants with unisexual flowers, that is, the stamens in one flower and the pistil in another; the gooseberry and currant family (natural order Grossulariacea), containing shrubs with regular flowers, four or five stamens, and succulent fruit; and eight other orders.

The epigynous section includes the large order of umbelliferous plants, which may generally be distinguished amongst British plants by the flowers and fruit being borne on umbels, as in the carrot, parsnip, hogweed, parsley, &c.; the ivy family (or Araliacea), which only includes the ivy in Great Britain; the mistletoe family, of which we have only the common mistletoe as a representative; and the cornel family (natural order Cornacea), of which we possess only two species of cornel or dogwood.

We come now to the third sub-class above named, which contains the monopetalous exogens, in which the petals are united either at the base or

all together into a single corolla. In order to refer a plant readily to one of the twenty-three natural orders which this sub-class contains, it will be well to divide them into separate groups, of which two will answer our purpose, viz. : 1. Those in which the corolla is epigynous, or upon the ovary. (In these instances the ovary is inferior, or below the corolla.)

2. Those in which the corolla is hypogynous, or surrounds the ovary. (In these the ovary is called superior, or above the insertion of the corolla.)

The monopetalous flowers with an inferior ovary have in some orders the stamens attached to, and borne upon, the inner surface of the tube of the corolla, and in others the stamens are not so attached. The stamens are attached to the corolla in the honeysuckle family (or Caprifoliacea), the bedstraw family (Rubiace@), the valerian family (Valerianacea), the teazel family (Dipsacea), and the large composite family (Composite), to which order the daisy and dandelion belong. The stamens are free, or not attached to the corolla, in the bluebell family (Campanulacea) and the heath family (Ericacea).

Monopetalous flowers with a superior ovary may have the corolla regular or irregular, the orders in which the corolla is regular being the most numerous, and includes the primrose family (Primulacea); the holly family (Aqui foliacea), which only contains one British species; the jessamine family (Jasminaceae), which is represented in Britain only by the ash and the privet; the periwinkle family (Apocynace@), which includes the two species of periwinkle; the gentian family (Gentianacea); the polemonium family, with one British species; the convolvulus family (Convolvulacea); the borage family, (Boraginaceae); and the nightshade family (Solanaceae). The orders in which the corolla is irregular are the butterwort family (Lentibulacea), the broomrape family (Orobanchaceae), the figwort family (Scrophulariacea), the labiates, or mint and thyme family (Labiata), and the verbena family (Verbenacea), which contains but one British species. There are also two orders associated with the monopetals having regular corollas, in one of which (Plumbaginace@) the ovary is simple but bears five styles, and in the other the flowers are small and usually borne on dense spikes (the plantain family or Plantaginaceœ), each flower having four stamens.

The fourth and last sub-class of exogens have apparently but one series of floral leaves, the calyx and corolla being united into a perianth, or both are absent. This sub-class contains a large number of orders, which include most of our forest trees and some herbaceous plants.

The endogens, or monocotyledonous plants, still claim a passing notice. It should be observed that in most of the exogens (dicotyledons) the parts of the flowers are in fours or fives, or some multiple of those numbers, whereas in endogens those parts are usually in threes or some multiple of that number, as, for instance, three or six petals and three or six stamens. There is, however, an exception to this rule in one group, in which there is either no perianth or it consists of four small sepals. This group contains the bulrush, arum, duckweed, and grasswrack families. There is also another group in which the perianth, or envelopes of the stamens, consist only of chaffy scales, as in the grasses and sedges. The rest constitute two groups, in one of which the ovary is superior, and in the other the ovary is inferior. Those in which the Ovary is superior contain one order in which the ovary is apocarpous, that is, the modified leaves of which the ovary is composed are all distinct, forming, when matured, a compound fruit. This is the alisma family, which includes

the arrowhead, water-plantain, &c. The other orders with a superior ovary are three: the lily family (Liliace@), the rush family (Juncace@), and a little order with but one British species named Restiaceæ.

The orders in which the ovary is inferior are five. In one the perianth is very irregular, and the stamens and pistil are combined into a single column: this is the orchis family (Orchidacea). Another order consists of water-plants (Hydrocharidea), of which the anacharis is one species, the frogbit another, and the third and last is the water-soldier. One order includes but one species of climbing plant, the black briony, and the order is named Dioscoridea. There remain, therefore, only two other orders which require to be distinguished from cach other. In one order (Iridacea) the number of stamens is three, and in the other (Amaryllidacea) the number of stamens is six in cach flower.

Thus far we have briefly characterized the classification of flowering plants. The limits of the present work would not permit us to do more; but what we have accomplished will, we trust, serve as a key to the comprehension of some book which contains the descriptions of the orders, genera, and species of British plants, such book being usually termed a "Flora." Until the elements of botany which we have set forth are mastered, the "Flora" will, for all practical purposes, be a sealed book. Herein is presented the most tedious and least interesting portion, but essential as letters to one who would learn to read. After the wilderness cometh a Paradise. Whoever has toiled with us to this resting-place may take heart, for his future progress in the study of plants will be comparatively easy and amply reward him for the labour of the past.

COLLECTING AND PRESERVING PLANTS.

A collection of dried plants is not only very useful and instructive, but care and neatness in the execution may make such a collection very pretty. Such collections are usually called a herbarium, and every British botanist is ambitious to possess a herbarium of British plants. For such a purpose a few plain rules and instructions are all that is necessary, provided a good will is ready for the work.

Having resolved upon forming a collection, it will be prudent to prepare the tools beforehand, and these should consist of the pocket-lens already described, a tin box or vasculum, such as a japanned sandwich-box. We once knew an enthusiastic youth who made extensive collections in an old candle-box, slung at his back with a piece of twine. A few quires of paper of a spongy nature, so as to absorb moisture (such as grocers employ for wrapping sugar will answer the purpose), but the size should be a little larger than that of the paper on which it is purposed ultimately to mount the specimens. A very good size for a sheet when folded in half is 17 in. by II in., or it may be this size and not folded, which is perhaps most convenient. A stout deal board for the top and the bottom, and this also half an inch larger each way than the paper, should be provided. Three or four bricks tied up in brown paper will serve as weights, each brick forming a parcel. This will be all that is really essential until the plants are dried and ready for mounting.

As ferns are very good plants to commence with, and perhaps the easiest of any to preserve, we will apply our remarks to them, and when the method of drying is acquired by experiments upon them, other plants may succeed.

The collection of ferns for transplanting and the collection of fronds for preservation as botanical specimens are to be pursued at very different periods