brilliancy of colour. That species most common in this country is the Chrysis ignitis; it dwells in holes of walls, harbouring between the stones and the mortar that cements them, where it lays its eggs. The larvæ resemble those of the wasp. It is about the size of the common window-fly, and is of a rich deep gilded azure on the head and thorax, with the abdomen of the most splendid reddish gold colour.

I will now introduce to you a more intimate acquaintance, the genus Vespa, or Wasp, whose external appearance is too familiar to need description.

They are of a very voraceous disposition, living occasionally on flesh,and are, as you know, extremely destructive to fruit, but as they do not lay up a store of honey for winter use, but few of them survive that season, and those which do, are in a torpid state.

Son. The importance of destroying wasps in April and May becomes evident when we are told that female wasps alone survive the winter, and that the produce of each individual of the vaspa vulgaris, then suffered to escape, is estimated by Messrs. Kirby and Spence, as well as other entomologists, to amount in autumn to 20,000.

Mr. B. Vespa crabro, or the Hornet, is a large species of wasp, with which you are, no doubt, acquainted.

The next genus is that of Apis or Bee. The genus is extensive, and is divided by Linnæus into two classes: those in which the body is but slightly covered with fine down, and those that are thickly clothed with hair. The latter are commonly called Humble Bees. Some kinds live in society, others dwell and work in solitude, building the cradles for their progeny with the leaf of the rose-tree, of which the Leaf-cutter bee is an example. The Mason-bee uses a kind of plaster, and the Wood-piercer saw-dust for the same purpose. The Carpenter-bee is so named from its habit of forming long, tubular cavities in wood. These insects have been known, with the multitude of these apertures, to have done serious injury to the majestic oak.

Were I to mention every particularity in the history of these interesting insects, I should extend our lesson to an unreasonable length, therefore I hope you will be satisfied with those leading features that I have selected for your instruction, and pursue the inquiry by your own attentive observation.

Botany.

Mr. B. The next portion of our subject is that highly ornamental, and no less useful, part of a plant-the leaf. In by far the greater number of plants the leaves consist of their flattened expansions; in which, the vascular portion, termed veins or nerves, is arranged in a kind of network, having the interstices filled up with cellular tissue-here termed the parenchyma, and the whole is invested with the epidermis. In Dicotyledons, the vessels proceed immediately from the medullary sheath. Leaves are exceedingly diversified in form, in the figure of their outline, in their position with respect to each other, in their texture, and especially in their degree of development.

It is the opinion of botanists that the most remarkable of the forms we meet with in leaves are owing to the peculiar manner in which the veins ramify in the parenchyma; that one class of forms is produced when the veins pass straight from the top of the petiole to the margin; another class, when they curve inwards and grow to one another without touching the margin; a third, if they pass in parallel lines from the base to the apex of the leaf, and so on: and hence the arrangement of veins has been made the fundamental principle of a classification of their modifications. Upon this principle the three following primary groups have been proposed:-1. Fork-veined; 2. Parallel-veined, of which straight-veined and curved-veined are forms; 3. Reticulated, to which are referred the ribbed, the radiated, and the feather-veined leaves.

Instances of the fork-veined leaves are most usual in ferns. Parallel-veined leaves are characteristic of endogens, in which they occur in two very distinct forms. The veins pass straight from the lower to the upper end of the leaf, running parallel with the mid-rib, as in grasses and lilies, whence they are called straight-veined; or they diverge from the mid-rib towards the margin, where they lose themselves, and are called curve-veined, as in the Indian shot (Canna), the arrow-root plant (Maranta), and the plantain (Musa). Reticulated, or netted, leaves are formed by the perpetual branching of veins, whose ramifications become gradually smaller and smaller, and growing to one another, divide the leaf, as in the rose, into an infinite number of angular spaces, and form that beautiful network which is so much admired in this group. When certain parts of the leaf contract and harden, spines are formed, as in the edges of the common holly leaf. In the Nepentes, or the true pitcher plant of India,

the petiole is partly round, and, in its common state, partly expanded into the form of a leaf, and partly rolled up into a pitcher, leaving the blade of the leaf at its extremity as a cover to the pitcher.

At the base of some leaves, as noticed in our second lesson, page 73, and on each side of their axils, there are appendages of a foliaceous character, sometimes resembling the leaflets of compound leaves, and sometimes like small membranous scales. These are termed stipules, and are very characteristic of certain groups of plants, but are entirely wanting in others. They are never found on any monocotyledons, or on any dicotyledonous plant where the petioles are sheathing. When the whole leaf stalk, or petiole, is transformed into what is termed a tendril, it serves to support the weak stems of certain plants, by twisting round the branches of others in their neighbourhood.

Bracts are generally defined to be all leafy bodies which intervene between the calyx and the leaves. As all leaves have the power of forming leaf-buds in their axils, so have all bracts the power of forming leaf-buds in their axils, and it rarely happens that flowers occur which do not thus originate. Hence it is a general rule, that where bracts are found flowers may also be expected. In the term Inflorescence is included not only the flower which proceeds from the development of the flower-bud, but also the stalk on which it is placed, and any of those other various appendages upon it, which are always more or less distinct from true leaves.

A perfect flower consists of three principal parts-namely, the floral envelopes, the fructifying system, and the fertilizing system. The manner in which the pieces of the floral envelopes are respectively arranged in the flower buds is called their aestivation, and have received certain distinctive names, of which the following are the most remarkable :- Valvate, when the pieces fit exactly to each other by their edges, as in the calyx of the Mallow; Imbricated, when the pieces are placed in part externally, and in part internally, so that the latter are covered over by the former, as in the calyx of Hypericum; Twisted, or contorted, when each part is turned slightly on its own axis, so that by one of its edges it covers its neighbour, while it is, in like manner, itself covered by the piece which is next it, as in the corolla of a Mallow. If the pieces of the floral envelopes are all distinct, this fact is expressed by prefixing the word poly (many) to the part which is spoken of, as polysepalous, if the calyx consists of several pieces, or sepals; and polypetalous, if the corolla consists of several petals. But if the pieces grow together by their edges and form a tube or cup, we then say monosepalous,

or monopetalous, that is onesepaled or onepetaled, by which is to be understood that they are all grown into one. The Greek privative a is also employed to designate their absence, as asepalous or apetalous. When the calyx is distinguishable from the corolla, it is commonly known by being smaller, greener, or more leaf-like, or more permanent. But such characters will not always indicate it, for we find it more richly coloured and larger than the corolla in the Fuchsia, and more deciduous in the Poppy. In fact, there seem no means of defining the calyx better than as the most exterior whorl of the floral envelopes; and consequently the name is so applied, whatever the colour, size, or other characters of the exterior whorl may be; and hence if there is only one whorl, that one is calyx. The corolla, which, it will be seen from what has lately been said, is only to be known with certainty from the calyx by its being placed between the part and the stamens, is often, nevertheless, the most conspicuous part of the plant, because the gay colours and the fragrant odours of flowers are generally resident in it. The pieces or petals, of which the corolla consists, are sometimes so much narrowed towards the base as to be separable into two parts, just as a leaf may be separated into a stalk and blade, in that case the stalk part of the petal is called the unguis or claw, and the blade has the name of limb. It is probably by petals of this sort that monopetalous corollas with long tubes are formed the border consisting of the limbs, the petals and the tube of their claws in a state of adhesion. The orifice of such a tube is called the throat or faux.

The fertilizing system consists of the organs which are arranged between the floral envelopes and the pistil or fructifying system. Such organs are technically called stamens, and usually consist of two parts, viz., a slender white stalk or filament, and a yellow or brown head or anther. An accurate idea of the normal state of the filament and anther may be taken from the Lily. In that plant the filament is a long, fleshy, awl-shaped, greenish-white body, the surface of which is furnished with stomates, and the centre with a bundle of vessels. On its point is placed the anther, which is a narrow, reddish-brown body, having a deep furrow passing down its longer diameter, and being thus separated into two parallel lobes. The part that unites the lobes is a continuation of the filament, and is called the connective. Each lobe, before it opens, is marked in front by a shallow furrow, which passes from end to end of the lobe, dividing it into two somewhat equal parts. In course of time, the sides of the lobe contract and separate at the last mentioned furrow, which consequently opens, and allows a brownish-orange powder, named pollen, to fall out. The two sides of the lobe

Ꮓ

when thus separate are called valves, and the furrow itself the suture, or line of dehiscence. This may be considered typical of all filaments, and of all anthers. Both these parts are, however, subject to numerous important modifications. In the Mallow, the filaments of a great many stamens, grow together into a tube, and are called monadelphous; in the Pea they grow into two unequal parcels, and are diadelphous ; in the Hypericum they grow into several parcels, and are called polyadelphous. In common groundsel, and many others, the anthers unite to each other by their edges, and are called syngenesious.

In the normal state of a flower the stamens arise from the angle formed between the case of the Calyx, or Corolla, and the ovary, and are then said to be hypogynous; but in the Plum, the stamens grow by their lower end to the side of the tube of the Calyx, only separating from it at the line where the petals arise; they are then called perigynous; and in the myrtle they not only grow thus to the side of the tube of the Calyx, but also to the face of the ovary, and join these two parts into one body; from this cause they look as if they grew upon the top of the ovary, and are said to be epigynous.

The Pollen consists of a prodigious multitude of little grains, whose figure is generally uniform in the same species, but which have some hundred modifications of form in different species, and which vary in size from theth to the 1th of a line in diameter. We reserve further details for the physiological department, when we shall speak of the manner in which the grains act upon the stigma, in securing the fertility of the ovule.

The fructifying system occupies the centre of a flower, and is the part round which all the other parts are arranged, it is generally called the pistil; the pistil consists of certain component parts called carpels, (from G. Karpos, fruit). A carpel consists of ovary and ovules, style and stigma. The ovary is the lower portion which is hollow. The ovary tapers upwards into a slender horn or thread called the style, and on the point of that organ there is a humid space, destitute of cuticle, and usually a little, sometimes very much distended, which is the stigma. Each carpel is an organ analogous to a leaf folded inwards upon its midrib, so as to bring the edges into contact, which cohere and form the placenta, and upon this the ovules are produced. The ovule (from ovum an egg) or young seed, appears to the naked eye as an oval grain with a mother-of-pearl colour, and when crushed seem to be simply a bag of gelatenous matter, but in reality it is an organ whose structure is by no means so simple. It consists of a central part called the nucleus, where the rudiment of an embryo is uniformly found first to