and reticulated. The root is always fibrous, and very often the stems and branches protrude fine radicles whenever they lie in contact with the ground, or body which supports them. Some species are so minute that a glass is necessary to recognise them; yet even in these there may be a stem, for very few mosses are destitute of that part, though in some it is extremely short. Some species have an arborescent habitude, and present the appearance of a beautiful tree in miniature. In general they are from one to three inches in height, though the great hair-moss (Polytrichum commune) which flourishes in marshy grounds, and some species of bog-moss (Sphagnum) which grow demersed, acquire a stature of above two feet.

The calyptra is generally, I believe, thought to be a corolla. Perhaps an attentive investigation of the office which nature intends the conical covering or calyptra of the young flowers in Eucalyptus to perform, might throw some light on the subject, which, whatever may be individual opinion, is certainly very obscure. It sometimes falls off very soon, but no moss wants it altogether. In the Polytrichum genus it is hairy. The Operculum seems not to be just so essential a part, since in one genus, Phascum (earth-moss), it is wanting.

In the investigation of cryptogamic plants the student will require a microscope, at least if he intend to study them very attentively, and he should use one with simple lenses, since these magnify

enough for every botanical purpose, and show objects much clearer than the compound microscope. Ellis's Aquatic Microscope is in every respect the best. It is only occasionally however that this is required, and therefore a common magnifying glass (such as may be bought for a few shillings) will be more frequently necessary. The student will, by a little practice, learn to use the latter, and simple as the means may appear, he will find it to open up to him a new world of wonder, entertainment, and instruction. Insects, flowers, leaves, mosses, lichens, the time-stained bricks and stones of old walls, the bark of aged trees, and indeed almost every natural object which comes in his way, he may examine with pleasure and advantage.

Ireland has been emphatically called a paradise of mosses, and there can be no doubt that the humidity of that country is very favourable to their growth. Most of these vegetables, indeed, prefer moist and shady situations, and some of them not only grow entirely immersed in water, but the Fontinalis antipyretica delights in the neighbourhood of cataracts, and flourishes most where the stream is most turbulent. In tropical countries, mosses prefer the shade of rocks and woods, but, still more, mountainous and alpine situations, where the heat and dryness of the climate are moderated by the elevation.

The mosses, however, like many other cryptogamics, are extremely tenacious of life, and though

rendered as dry as chaff, will, when again moistened, resume their functions and freshness of appearance as before. Hence there is scarcely any situation where air and light have a free access, in which some species may not be found, and we may observe on old walls, &c. exposed to the hot summer's sun, the tufts of moss and patches of lichen which cover them, burnt up, and, as it were, parched to dust, resume, after a heavy or continued shower of rain, their pristine vivacity and picturesque beauty. I have remarked, however, that when some mosses are attacked by drought at the time their capsules are ripening, but not yet come to maturity, the latter are instructed with the property of succulent plants, and absorb, but do not exhale moisture, so that the ripening of the seeds goes on unchecked, though the heaven denies it rain, and the earth is as iron. Still, however, mosses in general affect temperate and cold climates, and with the lichens they form the last trace of vegetation towards the limits of perpetual snow, whether on the tops of mountains or at the regions of the poles.

In the economy of nature, mosses are, perhaps, of more consequence than is yet ascertained. Still, we know that they protect innumerable young plants and seeds from the summer's heat, and the winter's cold. They form a retreat for insects and other animals, and serve as a soft bed for the young of birds. In cold countries they may protect trees

from the cutting north-wind, for it is observed that they and other cryptogamics grow chiefly on the northern side of the trunk and branches, and this forms one of the marks by which the Canadian savage traces his way through the pathless forests.

The economical uses of the mosses are not numerous. The bog-moss (Sphagnum), from its property of retaining moisture, and at the same time being little liable to decay, is of considerable use in packing up young trees for sending to a distance. In Lapland this moss is employed as a soft bed for infants, and the Polytrichium commune serves a similar purpose for the adult.

Herb a frond, capsules not opening with a lid. If the mosses be beautiful objects in the microscope, yet we must admit that in this respect they are surpassed by some plants of the present Order; in proof of which let me refer you to Dr. Hooker's splendid work on the British Jungermanniæ, the exquisite figures of which will, I hope, strike you with astonishment at the workmanship which nature exhibits in the formation of most of these humble vegetables. Until after some experience you will probably confound several of the Jungermanniæ with the real mosses, but should the specimens you collect be in fruit, you will observe that, as in Jungermannia complanata (flat jungermannia), Fig. 84, the capsule, instead of being covered by an operculum, and opening by a peristome, splits

into four parts or valves.

This species is common

on trees in moist situations, and may be found in fruit from January to April.

(a) A plant of natural size in fruit.

d

(b) The fruit magnified, showing the perichætium
or sheath, the peduncle rising from it, and the
capsule at top not yet burst.

(c) The capsule splitting and discharging the seeds.
(d) The capsule empty showing its four valves.

There are several other genera in this Order which we cannot attend to.

4. ALGE. Flags.

Herb, a frond, having the seeds either imbedded in its substance or in that of some kind of receptacle attached to it.

You have observed the picturesque stains, and variety of colours assumed by rocks, old trees, and walls. These in general are produced by plants called Lichens, which belong to the present Order.

The fruit of the genus Lichen consists of tubercles, or of saucer-like bodies, in which the seeds are imbedded. The first time you take a walk, examine some of the bright yellow patches which you can scarcely fail to observe on old branches of trees,